http://www.cfe.co.jp/tactaudio/images/boz/boz216_panel4_600.jpg

http://www.cfe.co.jp/tactaudio/images/boz/boz216_2200_stack600.jpg

http://www.cfe.co.jp/tactaudio/images/boz/boz2200_inside600.jpg

http://www.cfe.co.jp/tactaudio/images/boz/boz216_inside600.jpg

http://www.cfe.co.jp/tactaudio/images/boz/boz216_2200_dafuture600.jpg

http://www.cfe.co.jp/tactaudio/images/boz/boz216_2200_back600.jpg

Hi

I have seen and heard such a system... PhilinNYC provided me with the opportunity ... I heard the system for close to 4 hours... Quite sweet sounding, actually I have found that sweetness in many of the new digital amplifier I have auditioned: most sound somewhat closed on top. I think many designers have preferred to curtail the high frequencies so that not to expose the theoretical weakness of the breed: Inaccurate High frequency reproduction... .

The amount of control provided by this system is bewildering and has the potential to become the cause for a lot of mischiefs if the owner does not learn and discipline self....
Tzucc I have read about the Lake EQ I think the Boz/TacT system goes many steps further... far from just being an EQ...
I do believe however that in the present state of affair, conventional products provide a better experience, a better fac simile if you will of the absolute... Yet I know for a fact Digital Room Correction is the future...

Hi

I have seen and heard such a system... PhilinNYC provided me with the opportunity ... I heard the system for close to 4 hours... Quite sweet sounding, actually I have found that sweetness in many of the new digital amplifier I have auditioned, they sound somewhat closed on top. I think the good designer have preferred to curtail the high frequencies so that not to expose the theoretical weakness of the breed: Inaccurate High frequency reproduction... . The amount of control provided by this system is bewildering and cause for a lot of mischiefsin one does not learn and discipline self....
Tzucc I have read about the Lake EQ I think this system goes many steps further... far from just being an EQ...
I do believe however that in the present state of affair, conventional products provide a better experience, a better fac simile if you will of the absolute... Yet I know for a fact Digital Room Correction is the future...

Apologies in advance if I'm misunderstanding you.

I think you may have not spent enough time with different TACT systems. Did you just hear the BOZ unit or the TACT correction preamps? How experienced is that user and what is the setup? Did he run you through multiple target curves? The results are all in the target curves you draw and proper setup.

I have had all sorts of high end gear and nothing brings as much transparency or makes as big of positive impact as advanced room correction combined with sensible room treatments. TACT systems are definitely not just EQs. They do frequency, time alignment, time domain and level correction using impulse response. They can also layer fletcher-munson curves. The TACT systems have been out there since 1996 and have gone through several hardware and software upgrades. There are also several other advanced systems out there, some of them purely PC based.

The versatility of these setups is also amazing. In my 2.2. setup I can use cornerload woofers, set external crossovers and take separate impulse response of each speaker and woofer. In my 5.1 setup, I set external digital crossovers to bi-amp each of the amps and can route/mix signals however I want. The visual tools make everything straightforward (ok, maybe not straightforward) and easily verifiable.

Anyway, I have owned many pieces of traditional high end gear and TACT room correction gear. Unless you have a perfect room, nothing will get you closer to transparency than a properly corrected setup. One listen to my 5.1 setup, even with the panel in the middle, makes that abdundantly clear.

The future is definitely here. I wouldn't let one sitting with one system make you think otherwise.

http://i68.photobucket.com/albums/i24/sleestack666/SBR.jpghttp://i68.photobucket.com/albums/i24/sleestack666/DSC01162r.jpg

Uncorrected to almost corrected (although it needs more target work) in my 2.2. Notice I had to further attenuate the treble.
http://i68.photobucket.com/albums/i24/sleestack666/TACT2r.jpghttp://i68.photobucket.com/albums/i24/sleestack666/TACT1r.jpg

TCS MKII... critical tool (uncorrected):

http://i68.photobucket.com/albums/i24/sleestack666/5.jpg

Hi

I actually came with an extremely positive impression of the system. I do however maintain that many of the new "digital" amplifiers" do not sound as open and extended as the best conventional ones. I will continue to follow the technology , TacT in particular (Boz?) as this is the way of the future... I have also edited my post so that it does not come across as a negative assessment

TCS MKII... critical tool (uncorrected):

http://i68.photobucket.com/albums/i24/sleestack666/5.jpg[/QUOTE]


WELL where is the Corrected graph?

So is this system capable of acting as an active crossover as well as performing room correction? (i.e. can the 3 amp module inputs be shorted)

So is this system capable of acting as an active crossover as well as performing room correction? (i.e. can the 3 amp module inputs be shorted)
Greg,

Yes - if you look at the TacT windows closely, you will see the specifications for "CRO" and
"CRO-SUB". "CRO" is the high-pass crossover option for the mains, and the other is the
low-pass crossover for a sub.

It appears these have been set for a 10th order crossover at a frequency of 280 Hz.

The specs on the optional crossover package available on the "Boz" can be seen at:

http://www.tactlab.com/Products/BOZ/CrossOverPacakge.html

WELL where is the Corrected graph?

I changed the setup recently, so I have only taken the uncorrected measurements. After I design my curves, I'll remeasure that system.

So is this system capable of acting as an active crossover as well as performing room correction? (i.e. can the 3 amp module inputs be shorted)

The RCS 2.2XP and TCS MKII can both do correction (dynamic correction, in the case of the RCS) and crossovers on all 4 channels. The TCS MKII is fully programmable, and can do crossovers and correction on 3 subs.

The BOZ amps can do crossovers or correction. When used with a TCS MKII, you can do sub crossovers and correction through the TCS MKII and use the BOZ amps to further route signals and set crossovers for bi-amp setups like mine. BOZ amps accept discrete digital channels from the TCS MKII.

Hi

A little confused about the TacT/Boz... I read news about the company having broken up in 2005.. What is the situation ? Seems they are back to be one big happy family. Can someone enlighten us?

Does the preamp offer HDMI inputs? 1.1, 1.2, 1.3?

Does it support the new lossless advanced audio codecs? Or at least multi-channel LPCM?

Does the preamp offer HDMI inputs? 1.1, 1.2, 1.3?

Does it support the new lossless advanced audio codecs? Or at least multi-channel LPCM?

The TCS MKIII will this year. The TCS MKII uses its own multichannel system.

Mattias:
Peter Lingdorf took off and started his own digital amplifier company Lindorf audio. The reviews are not so hot.

Boz the head engineer retained the ip, kept the name Tact and now started the BOZ line.

Sleek said: "The RCS 2.2XP and TCS MKII can both do correction (dynamic correction, in the case of the RCS) and crossovers on all 4 channels. The TCS MKII is fully programmable, and can do crossovers and correction on 3 subs."

The TCS Mark 3 can do Dynamic Room Correction and cross talk cancellation which expands the soundstage, it will be HDMI 1.3 compliant and expand it's functionality to 12 channels, I only hope they retain the old firewire in for sacd/dvd-a or change to denon link.

Hi

A little confused about the TacT/Boz... I read news about the company having broken up in 2005.. What is the situation ? Seems they are back to be one big happy family. Can someone enlighten us?
Frantz,

Still two pieces. When you go to the TacT website:

http://www.tactaudio.com/

you get a choice of Boz's US company still called TacT:

http://www.tactlabs.com/

or Lyngdorf's European company:

http://www.lyngdorf.com/ContentId/334/Default.aspx

if you look at the TacT windows closely, you will see the specifications for "CRO" and
"CRO-SUB". "CRO" is the high-pass crossover option for the mains, and the other is the
low-pass crossover for a sub.I saw that (which is why I asked the question if it could implement the crossover as well as room correction). However, there doesn't seem to be an easy way to drive all the amps from the same 2ch source? (i.e. 3 amp modules for a 3-way speaker system) This system seems to be setup for SACD/DVD-A/HT where you'd have 6+ channels of signal routed into the amps which could then perform bass management and room tuning on the signal (vs a room correcting active crossover for a 2ch system).

I saw that (which is why I asked the question if it could implement the crossover as well as room correction). However, there doesn't seem to be an easy way to drive all the amps from the same 2ch source? (i.e. 3 amp modules for a 3-way speaker system)
Greg,

There are several ways of doing what you want to do - that is have 3 pairs of stereo channels
that are crossed over and room corrected.

For example, one method is to use either a TacT RCS 2.2x or Tact RCS 2.2XP and 3 TacT
stereo digital amplifiers. You can use the RCS to do the room correction and crossover
calculations and download those into the digital amps. The RCS is then used as a preamp,
and the TacT amplifier voltage supply rails are slaved to the RCS for volume control.

One Stereo Times reviewer, Don Shaulis uses a TacT 2.2x and 3 S2150 amps to tri-amp
his Apogee MiniGrand; which is 3-way - midrange/tweeter ribbon, woofer ribbon, and
dynamic subwoofer. Check the sidebar on Associated Equipment and his description of the
system under the heading "Performance" at:

http://www.stereotimes.com/cable011306.shtml

If you want to do the same with the Dynamic Room Correction; which corrects for the volume
level also via the Fletcher-Munson curves; one would need to substitute a 2.2XP for the 2.2X
and the newer S2150 XDM for the S2150.

The 2.2X and the 2.2XP can also be fitted with a couple of stereo DACs each to provide 2 stereo
pairs of line-level output . In that case, one could dispense with 2 of the 3 stereo digital amps,
and use the 2 stereo pair analog outputs of the RCS 2.2X or RCS 2.2XP to drive a couple
analog stereo amps to provide for 4 channels and the remaining stereo S2150 or S2150 XDM
which would be slaved to the RCS; would provide the other 2 channels for a total of 6 channels.

The older RCS 2.2X requires a computer during setup to compute the correction filters and
download those into the RCS 2.2X and S2150 amps. The newer products like the RCS 2.2XP
and the Boz 216/2200 have on board processing power, so they don't need a computer during
the setup phase. However, TacT has a nice GUI interface, screen shots of which are attached
to previous posts; that can be utilized optionally with the 2.2XP and Boz; and is required with
the 2.2X.

The Boz216/2200 system has even more flexiblity and expandability. You can download a
User's Manual for the Boz at:

http://www.tactlab.com/Resources/Downloads/BOZ216-2200.html

Page 25 of the manual shows how you "daisy-chain" 3 stereo amplifier modules in order to
form a tri-amp system, like you want to do.

The TacT systems are very modular and can be mixed / matched in various ways.

The latest edition of "The Absolute Sound" has a review of the TacT RCS 2.2XP
by Anthony Cordesman

A power DAC! Interesting technology application. A TV transmitter company, Acrodyne Industites, tried this too in the mid 1990s for high power AM video (in the NTSC RF system video is AM and the audio is FM). They never got the bit switching generated harmonics low enough to be commercially viable but here we are talking hundreds of MHZ and power levels of tens of kilowatts.

Seems however it could work quite well in the audio passband.

Hi,

Here is a picture of my setup with 3 TacT S2150X (tweaked) in an tri-amp configuration: http://gallery.avsforum.com/showfull.php?photo=23270.

In this configuration the 3 S2150X are used to power the 2 main speakers and the 2 subs: Left amp is for left speaker woofer and tweeter, center amp is for left and right subwoofers, right amp is for right speaker woofer and tweeter.

Nore: the center channel on the picture is powered by another amp (S2150) not visible on the picture.

Michel

In this configuration the 3 S2150X are used to power the 2 main speakers and the 2 subs: Left amp is for left speaker woofer and tweeter, center amp is for left and right subwoofers, right amp is for right speaker woofer and tweeter.

Michel,

Your mains are "vertically bi-amped" : and the subs are normal stereo mono-amped.

Morbius,

It is a mixture of vertical biamping for the mains and horizontal for the subs.

Each of the 3 amps receive the full stereo signal (the red box on the picture is an AES/EBU distribution box, 1 LR stereo input coming from a TacT TCS , 3 stereo outputs going to each amp) and then the amps implement crossovers and time alignment as needed:

1) the left amp extracts only the left signal from the stereo signal on its input and send the mid freq (150hz-3000hz, band-pass crossover) to its left output and the high freq (>3000hz, high-pass crossover) to its right output, these outputs are then connected to the left loudspeaker inputs (these loudspeakers don't have any analog crossovers inside, they are intended to be used with TacT amps)

2) the right amp does the same but on the right signal.

3) the center amp keeps the full stereo signal and implements a low-pass crossover (<150hz) and sends the filtered left and right channels to the left and right subwoofers.

Michel

Morbius,

It is a mixture of vertical biamping for the mains and horizontal for the subs.

Each of the 3 amps receive the full stereo signal (the red box on the picture is an AES/EBU distribution box, 1 LR stereo input coming from a TacT TCS , 3 stereo outputs going to each amp) and then the amps implement crossovers and time alignment as needed:

1) the left amp extracts only the left signal from the stereo signal on its input and send the mid freq (150hz-3000hz, band-pass crossover) to its left output and the high freq (>3000hz, high-pass crossover) to its right output, these outputs are then connected to the left loudspeaker inputs (these loudspeakers don't have any analog crossovers inside, they are intended to be used with TacT amps)

2) the right amp does the same but on the right signal.

3) the center amp keeps the full stereo signal and implements a low-pass crossover (<150hz) and sends the filtered left and right channels to the left and right subwoofers.

Michel

Michel,

You just described above what I said in my previous post.

Your mains are "vertically bi-amped"

Your subs are stereo mono-amped

Because you have only one channel going to each sub; they are
NOT "horizontonally bi-amped" - so there's NO MIXED biamping.

The subs are not bi-amped at all.

That's just normal stereo mono-amp.

All exactly as I stated before.

Look, you guys are talking past each other, and you're both right.

From the perspective of the signals, Michel's configuration is indeed triamped, because he's dividing the L&R signals into three frequency bands and amplifying each separately.

From the perspective of the speakers, Morbius is correct in saying that that the mains are biamped and the subs are mono-amped.

No contradiction. Morbius, I think you're just trying too hard to prove him wrong here when in fact you're simply talking from different points of reference. But frankly, Michel's point of reference is more informative for the sake of this discussion. After all, his configuration demonstrates the feasibility of using TacT equipment to do triamping, which was the issue at hand.

The one hitch in this setup is the need to distribute aech of the L&R signals to two separate inputs. That can be done very cleanly, but still, it would be good if the new Boz setups can eliminate the need to do that and do a full 3-way crossover.

Frantz, some excerpted specs I see on the tact page are:
Signal to Noise ratio +/-0.1dB
Frequency response 20Hz-20kHz 0.0005%
THD+Noise 0.0004%
Dynamic range 112dB

I don't get it.
What is 0.0005% doing attached to a freq response spec?
What is an SNR of +/-0.1dB?
THD+N of 0.0004% is excellent, if it was actual.

Morbius,

I was perhaps not totally clear (I actually did not mean that the subs are biamped... they are not, I just meant that they are wired horizontally as opposed to the main speakers) but as Michael wrote the system is indeed tri-amped from the signal perspective.

I decided to bi-amp the main speakers vertically to limit the length of speaker cables but it would have been as easy to triamp the whole thing horizontally: one amp for the tweeters, one amp for the mid, one amp for the subs. As a matter of fact, I initially had this horizontal configuration before I decided to review the cabling of my room.

The three drivers could have been in one single enclosure, it just happens that I use a separate enclosure for the subwoofer.

Note that my "subwoofers" are the Lyngdorf W210 (http://www.lyngdorf.com/ContentId/365/Default.aspx) (and Lyngdorf doesn't like to call them subwoofers but more a corner loaded woofer).

The signals coming from each individual drivers have been measured with the TacT TCS, and with the help of software tools, delays have been computed and implemented in the 2105X (the 2150X allows a delay resolution of 0.01ms). Once these delays are implemented in the amps the 3 drivers are time aligned and from the listening position the multiple enclosures virtually behave like one.

The TacT amps are indeed very flexible and ideal to implement multiamplified systems.

Michel

Hi Michael,

The one hitch in this setup is the need to distribute aech of the L&R signals to two separate inputs. That can be done very cleanly, but still, it would be good if the new Boz setups can eliminate the need to do that and do a full 3-way crossover.

The TacT/Boz amps works on the principle that they receive the full stereo signal and filter it internally. All TacT/Boz amps have a daisy chain feature that allows the input signal of one amp to be routed (untouched) to the next amp to implement multiamping. With the Boz amp (216/2200), the daisy chaining can be done with S/PDIF or AES/EBU, with the S2150X it is only S/PDIF. As the signal coming from my TCS is AES/EBU, I decided not to use the daisy chain feature of the amps but rely on this external distribution box such that all amps see exactly the same type of input.

I know some 5-way systems implemented with the TacT/Boz amps, there is almost no limit in the configuration.

Michel

Frantz, some excerpted specs I see on the tact page are:
Frequency response 20Hz-20kHz 0.0005%


Actually the frequency response is DC to 20khz

I know because Boz will modify the 216 to perform the following Rotary Woofer EQ utility.

0 to 10 Hz Flat

10 to 20 Hz EQ Boost Adjustable to 12 db per octave

The above yields up to 20Hz being 10 db above 10 hz.

Brickwall at 20 hz to cross over to cone subwoofer.

good going Peter... nice to see you working in the rotary woofer support!

No contradiction. Morbius, I think you're just trying too hard to prove him wrong here when in fact you're simply talking from different points of reference. But frankly, Michel's point of reference is more informative for the sake of this discussion. After all, his configuration demonstrates the feasibility of using TacT equipment to do triamping, which was the issue at hand.
Michael,

That's what I was trying to point out to Michel - there's no contradiction;
but evidently he thought so - and tried clarifying in post #20.

We already know that the TacT system can tri-amp from Don Shaulis's description
of his tri-amped Apogee MiniGrand. The way Don has tri-amped his system - only
his RCS 2.2x needs the L&R signals. All the amps are downstream of the RCS; so
there's no need for multiple distributions of the L&R signal.

The RCS has one set of high/low x-overs. The low pass is sent to an amp
driving the lowest driver. The high-pass is daisy-chained to 2 other amps
programmed with x-overs; one high-pass, one low-pass.


The one hitch in this setup is the need to distribute aech of the L&R signals to two separate inputs. That can be done very cleanly, but still, it would be good if the new Boz setups can eliminate the need to do that and do a full 3-way crossover.

The Boz does that. You feed L&R to the Boz and apply your choice of x-overs -
high-pass, low-pass, or band-pass. The outputs of thes x-overs are sent to
the amp modules after room correction filters are applied.

Hi

I will actually try this system with a secondary system built around a pair of Apogee Diva I acquired early this year... I will tri-amp them with Boz amplifiers... The level of flexibility afforded by the Boz/Tact system is extraordinary...

I was perhaps not totally clear (I actually did not mean that the subs are biamped... they are not, I just meant that they are wired horizontally as opposed to the main speakers) but as Michael wrote the system is indeed tri-amped from the signal perspective.
Michel.

I understand how your system is wired and that the subs are not bi-amped;
which is why I said they were stereo mono amped.

I'm just being picky about the use of the term "horizontal"

One doesn't normally use the term horizontal when describing speakers that are
mono-amped like your subs. There's no need to say horizontal since there's only
one way to hook-up a mono-amped stereo.

It's only when you bi-amp speakers that you have to use the terms horizontal and
vertical because there are two ways to bi-amp.

Since the subs are mono-amped; the use of the term horizontal is superfluous.
There's only one way to hook-up the subs.

Unless one has a 3-channel amp; there's no way to be purely vertical in a tri-amp
setup using stereo amps [ unless the amps can be bridged, or one is willing to idle
a couple of channels in separate amps]. One pair of drivers has got to be stereo mono-amped.

Hi Michael,



The TacT/Boz amps works on the principle that they receive the full stereo signal and filter it internally. All TacT/Boz amps have a daisy chain feature that allows the input signal of one amp to be routed (untouched) to the next amp to implement multiamping. With the Boz amp (216/2200), the daisy chaining can be done with S/PDIF or AES/EBU, with the S2150X it is only S/PDIF. As the signal coming from my TCS is AES/EBU, I decided not to use the daisy chain feature of the amps but rely on this external distribution box such that all amps see exactly the same type of input.

I know some 5-way systems implemented with the TacT/Boz amps, there is almost no limit in the configuration.

Michel

SPDIF and AES-3 are for the most part interchangeable.

AES-3 is a 1 volt 75 ohm signal using BNC connectors.

SPDIF is also 75 ohms and 1volt but typically uses RCA connectors. SPDIF also supports a fiber or "TOSLINK" interface. This is a visible light fiber technology with rather poor performance. It is distance limited and uses a lossy connection scheme. Not anywhere close to the quality of fiber systems in the telecommunications industry.

Just "AES" or sometimes called AES-1992 is a 5-10 volt balanced signal on twisted pair using XLR connectors or other multipin connectors such as DB or even terminal strips. A source and destination impedance of 110 ohms must be maintainned so no "Y" cables are allowed.

Now there is a slight difference in the coding. AES and AES3 have "channel status bits" where as the same byte field is used for copy protection flags in SPDIF. As copy protection was only ever implemented on consumer DAT machines, it is very rare. In almost all case SPDIF and AES-3 can be mixed with nothing more than RCA to BNC adaptors. I have seen some cases though where the channels status bit in AES-3 does confuse SPDIF consumer equipment.

AES-3 and AES-1992 can be mixed by using transformers designed for this purpose. This is very commen in the television industry as there is a fairly even mix of AES-3 and AES-1992 equipment on the market these days. But you can only reliably go through a transformer once before an active device as there is power loss in the transformerer. Of course the net effect is not noise and distortion as would be with an analog interface. You get clicks and pops when the error rate becomes to high to be corrected by the checksums embedded in the protocol.

Hi Morbius,

Ok concerning "horizontal" I see what you mean. I did not try to argue in my previous posts... I just did not get the point.

All the amps are downstream of the RCS; so
there's no need for multiple distributions of the L&R signal....

The RCS has one set of high/low x-overs. The low pass is sent to an amp driving the lowest driver. The high-pass is daisy-chained to 2 other amps programmed with x-overs; one high-pass, one low-pass.


With the RCS/TCS there are basically 2 ways to implement a multiamped system, in both case the amps are downstream the RCS/TCS but in the first case they are downstream the RCS/TCS LR and SubLR outputs (as you described: one sub crossover in the RCS/TCS, the other crossovers in the amps) in the second case the amps are downstrean the RCS/TCS LR output only (all crossovers are then implemented in the amps, as in my setup).

However in the first case (crossovers in both the RCS/TCS and the amps) it can be tricky to compute the exact delays to apply to the various drivers. The reason is that the RCS/TCS is only able to take measurements when the correction filters are not active, in other words the measurements will not take into account the additional delay introduced by room correction filter (this delay depends on the crossover type being used in the TCS/RCS and impact differently the main and sub outputs). The only way to correct this is to manually add this additional delay afterwards (after measurement via a separate measurement system for example). A guy on the TacT forum (Tony) measured these delays for different type of filters and published the results for reference (for those interested and who access to the TacT forum, it is there: http://tech.groups.yahoo.com/group/TacTAudioUsersGroup/message/20213)

Having all the crossovers inside the amps solves this issue, in this case the RCS/TCS delay introduced by room correction filter will apply equally to all the amps... no need to compensate one or the other. Note this issue may not exist with the new 2.2XP and future TCS 3 anymore, I just don't know.

The other advantage of the second configuration is the flexibility of filtering that can be achieved with the 2150X and the Boz amps: there is no limit to the crossover frequency (whereas there are limitation to the frequency range in the RCS/TCS and also the older 2150).

Final note: the additional distribution box in my setup is not compulsory at all, I could equally use the daisy-chain feature of the amps.

Michel

However in the first case (crossovers in both the RCS/TCS and the amps) it can be tricky to compute the exact delays to apply to the various drivers. The reason is that the RCS/TCS is only able to take measurements when the correction filters are not active,
Michel,

The new TacT preamps like the RCS 2.2XP; i.e. the ones that do DRC, can take measurements
with the filters engaged. These preamps have the processing power on board, so they can do
measurements and corrections in "real time".

Additionally, the 2.2 XP compensates for the delay times and saves them with the measurements;
no need to manually enter them. You just set the delay time to AUTO instead of a numerical
value.

Additionally, even with the older setup; you don't have to do things manually if you're clever.
You do the measurements and filter calculations in an "upstream" direction. So when the RCS
which is the most upstream component does its measurement of the response of the entire
system - the downstream filters in the amps are already loaded - and their delay is just like any
other delay to the RCS, and the RCS does its calculations with the delay due to the amp's
crossovers taken into account. That's because those delays are part of the measurement owing
to the fact that the amps and their crossovers were active when the RCS did its measurement of
the total system response.

If you're clever, you can get around the limitations of the older products, without resorting to
manual corrections. However, the newer products are even easier to use.


Having all the crossovers inside the amps solves this issue, in this case the RCS/TCS delay introduced by room correction filter will apply equally to all the amps... no need to compensate one or the other. Note this issue may not exist with the new 2.2XP and future TCS 3 anymore, I just don't know.

The new TacT 2.2 XP does solve the above problem.


The other advantage of the second configuration is the flexibility of filtering that can be achieved with the 2150X and the Boz amps: there is no limit to the crossover frequency (whereas there are limitation to the frequency range in the RCS/TCS and also the older 2150).

From Page 38 of the TacT 2150X manual; the minimum x-over frequency is 10 Hz and the
max is 24 kHz.

In post #26 of this thread, CINERAMAX reports that Boz will modify the 216 so that it can do
a crossover for those like tzucc with the Thigpen Rotary Woofer which essentially goes down
to DC.

Hi

I will actually try this system with a secondary system built around a pair of Apogee Diva I acquired early this year... I will tri-amp them with Boz amplifiers... The level of flexibility afforded by the Boz/Tact system is extraordinary...

The verstility of the TACT systems is definitely unique and allows for configurations most people would never attempt. In my 5.1 system, I bi-amp each of my 4 Andra II floorstanders via the BOZ216/2200. I removed the internal crossover at the binding post. I use the TCS for my sub crossover and signal routing.

If you were really crazy with the Boz setup, you could get a speaker with drivers, amp each driver separately and do each crossover via the Boz.

.
If you were really crazy with the Boz setup, you could get a speaker with drivers, amp each driver separately and do each crossover via the Boz.
Sleestack666,

As I recall, in the Apogee Diva, like the one Frantz has; the speaker itself holds just the drivers.
The various crossovers were supplied in a box that one normally put on the floor behind the Diva.

http://www.apogeespeakers.com/reviews/diva_stereophile_august1988.htm

"The Diva's passive crossover components are packaged in separate hem measuring
17" W x 13" D x 3" H, their intended placements right behind each speaker. The crossover
assembly, isolated mechanically from the speaker, sits on the floor supported by four large
rubber feet 1¾" high."

Frantz could just toss the box of crossovers, get a Boz system with 3 amp modules because the
Apogee Diva is a 3-way; and do as you said, perform all crossover functions as well as the
room correction with the Boz.

That way he won't have any passive component crossover networks in the audio chain.

Hi

That is exactly hat I will be doing. I sincerely believe active multi-amping is the best solution. I tried a few years ago to bi-amp with an FM Acoustics crossover and the results were good, the crossover was extremely expensive and I have since (1990) abandoned the active crossover route. I am very satisfied with my current passive crossover but I will definitely go active with the Apogee Diva which indeed has an outside crossover "box". I iwll not use it, rather I will use the Boz preamp. Now my questions
Where is the crossover function performed? In the preamps or the amps?
Do the Boz preamps provide multiple preamps ANALOG outputs? Which would have allowed one to use amplifiers other than Boz's?

Somewhat OT but I have in mind to build a Reference Nostalgia system . One of the best SS amplifiers I heard in the 80's were the Krell Reference Standard the KRS-100 and the KRS-200 Class A.. These beasts could power an arc welder not figuratively... literally. They could provide their full output with a 0.5 Ohm load provided your AC outlet could, 3200 Watts of pure class A !! They were liquid sounding very reminiscent of tubes the first and maybe last Krell amplifiers I liked... end of OT...

Where is the crossover function performed? In the preamps or the amps?
Do the Boz preamps provide multiple preamps ANALOG outputs? Which would have allowed one to use amplifiers other than Boz's?
Frantz,

You can download a copy of the TacT Boz-216/2200 User's Manual at:

http://www.tactlab.com/Resources/Downloads/BOZ216-2200.html

According to Page 5 of the Manual, the crossovers as well as the room correction filters run on
the Boz-216 control unti.

I think the Boz-216 control unit only offers digital control outputs meant for the 2200.
The RCS series like the RCS 2.2XP can be ordered with optional DACs for output to analog
amps. The product specification page for the RCS 2.2XP has a "configuration" page listing
the various options.

The RCS 2.2XP however is only a 2-channel unit; not a 3-channel. In order to use an
RCS 2.2XP; three S2150 XDM units would be needed; with 2 of them programmed to take
one of the crossed over outputs of the 2.2XP, and divide this output to drive two bands using
high-pass and low-pass filters programmed into the S2150 XDM units. [ This is essentially what
Don Shaulis has done to tri-amp his Apogee MiniGrand. See above]

Morbius,

Additionally, even with the older setup; you don't have to do things manually if you're clever. You do the measurements and filter calculations in an "upstream" direction. So when the RCS which is the most upstream component does its measurement of the response of the entire system - the downstream filters in the amps are already loaded - and their delay is just like any other delay to the RCS, and the RCS does its calculations with the delay due to the amp's crossovers taken into account. That's because those delays are part of the measurement owing to the fact that the amps and their crossovers were active when the RCS did its measurement of the total system response.

I did not mean the delays introduced at the amps level, these are indeed easy to measure, I was talking about the delay introduced by the RCS/TCS own correction filter, with the 2.2X and TCS mk2 these delays are not included during the measurement process and they impact differently the LR and subLR outputs. However, happy to read that the 2.2XP fixed this issue (no doubt the TCS mk3 will as well).

Michel

Where is the crossover function performed? In the preamps or the amps? Do the Boz preamps provide multiple preamps ANALOG outputs? Which would have allowed one to use amplifiers other than Boz's?

In the case of the Boz units, the 216 is a control and power supply unit. There is no audio signal input on the 216, all the audio signal are going directly to the 2200 (see page 16 and 18 of the manual). The 216 is acting as an interface to design the crossovers which are then implemented on the fly inside the 2200 DSP's.

Michel

IThe 216 is acting as an interface to design the crossovers which are then implemented on the fly inside the 2200 DSP's.
Michel,

Again, it's a question of semantics as to "where the crossovers and filters are".

The crossover's and filters are COMPUTED in the Box-216; because that's where the processor
lives.

Once the crossover and filter parameters are computed; they are downloaded via the RS-232
control lines to be implemented by the DSP chips in the 2200s.

I did not mean the delays introduced at the amps level, these are indeed easy to measure, I was talking about the delay introduced by the RCS/TCS own correction filter, with the 2.2X and TCS mk2 these delays are not included during the measurement process and they impact differently the LR and subLR outputs. However, happy to read that the 2.2XP fixed this issue (no doubt the TCS mk3 will as well).
Michel,

I'm more familiar with the RCS 2.2XP than with the RCS 2.2x - but I find it hard to believe that
the 2.2x introduces delays that it can't account for.

How would a 2.2x system ever work at all - for instance on a 2-channel system; if it introduced
delays of one passband relative to the other and could not account for that? For instance,
suppose the high-pass band correction filter was very simple, and required 10 msec of delay;
while the low-pass filter was complex and needed 20 msec of delay. That would mean that
the 2.2x was time-shifting the high and low passbands.

Actually, the delay time for a given filter is EASY to calculate for the processor that's calculating
the filter. The digital filters that TacT is implementing are basically approximate inverse Fourier
Transforms; they are discrete approximations to a temporal integral. The way the DSP chips
implement an integral over time is to put the signal through a delay chain; each stage of the
delay chain handing off the signal to the next delay unit downstream.

Therefore, at any given moment, the system has access to the signal at a variety of times. The
delay units that are upstream of the output are signals at "future" times relative to the output,
while stages downstream represent "past" times. The filter can be implemented by tapping the
signal from the various delay units, multiplying by a coefficient calculated for that delay stage;
and summing over all the delay stages.

When the processor knows what delay stages are needed; it knows how much delay this
process engenders, and should easily be able to calculate the delays. I don't know how
one can claim to be able to "time align" the signals, as TacT claims the RCS can do, if the
software doesn't correct for the known delays.

Michel,

I'm more familiar with the RCS 2.2XP than with the RCS 2.2x - but I find it hard to believe that the 2.2x introduces delays that it can't account for.


Please check the TacT forum on Yahoo, this has been discussed at length there. Check for Tonycdk posts.

Michel

Please check the TacT forum on Yahoo, this has been discussed at length there. Check for Tonycdk posts. l
Michel,

I've checked that forum before and I've found a lot of the people don't know what they are talking
about!!!

I've found that it is NOT a very good place to get ACCURATE information!!
As I recall, Agnes or Boz from TacT is frequently correcting people.

If you want accurate information about TacT gear; ask TacT!!

Does TacT say that they don't correct for the processing time of the 2.2x?

I'll believe THEM, if they do.

Greg

Are you planning to or currently use the TacT/Boz system?

Michel,

I've checked that forum before and I've found a lot of the people don't know what they are talking
about!!!

I've found that it is NOT a very good place to get ACCURATE information!!
As I recall, Agnes or Boz from TacT is frequently correcting people.

If you want accurate information about TacT gear; ask TacT!!

Does TacT say that they don't correct for the processing time of the 2.2x?

I'll believe THEM, if they do.

There are still clever people out there who know how to use an external measurement system (this site in French http://monsite.wanadoo.fr/francis.audio/page7.html shows for example how to align the drivers using Adobe Audition with the Aurora plugin, there is a paragraph on the TacT delays that mentions the problem).

Some have even been able to understand how the 2.2x and 2150 are working in details. See for example http://www.dirac-france.com/tacs/index.asp (a control software to load filters, including corrections inside the 2150) and www.acourate.com (a software tool box that offers alternative corrections that can possibly be loaded inside the RCS).

BTW, it is not possible anymore to use these software with the 2.2XP and 2150X as they do all the computation inside the unit and not in a computer anymore.

Michel

Some have even been able to understand how the 2.2x and 2150 are working in details.
Michel,

Ich no habla Francais

I do know the mathematics behind how the TacT works. It's really not difficult at all if you know
Fourier Transforms.

In essence, the TacT is measuring the Green's function of the audio system and room for the
microphone's location and the forcing function's locations are the driver positions.

You invert that response function and use it as a correction fitter.

You may "think" that some of the people are clever; but if you don't know the mathematics
you can't appreciate the fact that they appear to be parroting back audio folklore that has
more in common with pseudo-science than real audio science.

Perhaps you could give me an example of a post you thought was "clever".

In essence, the TacT is measuring the Green's function of the audio system and room for the microphone's location and the forcing function's locations are the driver positions.Green's functions? Don't make me laugh. I'm not saying that what TacT is doing is particularly simple; no do I disagree that some of the TacT fans are misguided on the science. But you're purposefully making it sound more complicated than it is.

Greg

Not too many people are as versed in Mathematics as you are yet I do not think it is wise to blanket a whole list of person as "not knowing what they are talking about". So let us chill on this.
Also I do not think it make a huge difference in sound quality if one multi-amp horizontally or vertically... The Boz system has a centralized power scheme so both approaches would yield the exact results. I will research a little more to know how it would handle "special" loads such as the Divas and am also interested in using different amplifiers in a TacT scheme while preserving the flexibility of their crossover implementation and the Room Correction. How would I accomplish this?

I also tried to send you a PM but your mailbox and mine, at the time were full... Mine is clear now

Greg's last post reminds me of a joke.

An engineer, a physicist and a mathematician are staying in three adjoining cabins at an old motel.

First the engineer's coffee maker sets fire. He smells the smoke, wakes up, unplugs the coffee maker, throws it out the window, and goes back to sleep.

Later that night, the physicist smells smoke too. He wakes up and sees that a cigarette butt has set the trash can on fire. He says to himself, "Hmm, How does one put out a fire? One can reduce the temperature of the fuel below the flash point, isolate the burning material from oxygen, or both. This could be accomplished by applying water." So he picks up the trash can, puts it in the shower stall, turns on the water, and when the fire is out, goes back to sleep.

The mathematician of course has been watching all this out the window. So later, when he finds that his pipe ashes have set the bedsheet on fire, he is not in the least taken aback. He says: "Aha! A solution exists!" and goes back to sleep.

Green's functions? Don't make me laugh. I'm not saying that what TacT is doing is particularly simple; no do I disagree that some of the TacT fans are misguided on the science. But you're purposefully making it sound more complicated than it is.
Michael,

I think likening what the TacT is doing is a Green's function is quite demonstrative.

That's essentially what the TacT is doing; it is measuring the response at one point in space,
due to an impulse source at another point is space. That's a Green's Function

Considering the algorithm as a Green's Function doesn't make it more complicated; it makes
it EASIER!!! It takes the mystery out of what the TacT is doing; and is a SIMPLE explanation
for the operation of the device.

Once you know the Green's Function of a system - how the output varies as a function of
the input; you can convolve the Green's Function with the source to obtain a solution to what
the output will be. Green's Functions are elegant ways of solving complex problems.

Greg

Not too many people are as versed in Mathematics as you are yet I do not think it is wise to blanket a whole list of person as "not knowing what they are talking about". So let us chill on this.

I'm not trying to blanket all the people on the group as not knowing what they are talking about;
there are plenty that do know. In fact, Boz and Agnes from TacT have been known to frequent
there.

However, to cite posts on that group as an authoritative source for claims about the TacT
products, I think is misguided. There are so many that blather nonsense; just as we have
seen many blather nonsense on these Forums. Everybody has a right to say whatever
they want on Forums; so to consider posts on Forums as some authoritative source of
information is misguided.

It would be nice if there were online forums of some sort that were "peer-reviewed" like
scientific journals are. One could then have reasonable confidence that the information
that was provided had "passed muster" with the knowledeable people of the field.


Also I do not think it make a huge difference in sound quality if one multi-amp horizontally or vertically... The Boz system has a centralized power scheme so both approaches would yield the exact results.

If one is using identical amps; then you are correct that it would make essentially ZERO
difference. The one advantage I see is for vertically amping concerns the power requirements.
Suppose you horizontally amp, and there is big swell of bass that requires a lot of power. If
you are horizontally bi-amped; then the load will all be on one stereo amp which is handling the
bass, while its twin is loafing. It would be better for the two amps to share the load; which is
what happens in vertical amping. One channel of each amp will be loaded, the other loafing;
and the power supply only has to deal with one loaded channel; not two loaded channels.
[If the power supplies are heavily regulated and have enough power, so that you don't load
down the power supply with a heavy load; then there would be ZERO difference in using
the vertical vis-a-vis horizontal bi-amp method]


I will research a little more to know how it would handle "special" loads such as the Divas and am also interested in using different amplifiers in a TacT scheme while preserving the flexibility of their crossover implementation and the Room Correction. How would I accomplish this?


I believer there are quite a number of people who have used TacT amps with Apogees in
addition to Don Shaulis. Let me look into it further.

If you want to use amps other than TacT's digital amps; then you will have to convert the
digital output of the TacT to analog to feed a conventional analog amp. That most certainly
can be done with the TacT RCS preamps. The RCS preamps are available with optional
ADC and DAC added internally.

For example, the basic RCS 2.2XP comes in a version TacT calls D.DD; that is it only accepts
digital input, and outputs 2 digital outputs for high-pass and low-pass. If you want to play CDs
off your transport, that's fine. However, if you have an SACD player, the player can't output a
digital version as per Sony's license. The SACD player will only output analog - so you need
a ADC in the TacT to convert the analog from the SACD to digital inside the TacT. That would
be an A.DD configuration.

If you wanted to use some big monster amp like a Krell, Classe, or Mark Levinson to drive the
Divas; then you need the TacT to convert its output to analog. That's where the DACs come
in. DACs are also available, internally installed by TacT.

The most versatile TacT RCS 2.2XP system is the A.AA which accepts both analog and digital
input, and outputs both analog and digital outputs.

http://www.tactlab.com/Products/RCS22XP/configurations.html

The problem with the RCS 2.2XP is that it is a 2-way system; not a 3-way. [ DEQX is a 3-way,
BTW] You would need another level of crossover. It could be done passively; that is you would
let the RCS do the crossover between the woofer ribbon and the two higher ribbons. The
output of amp on the high-pass would then need to be connected to the Diva's passive
crossover box to get outputs for the midrange ribbon and the tweeter ribbon.

If you wanted to do all the crossover's actively, I believe there is an active crossover .
Gallant_Diva uses an active crossover by Davey to perform crossover functions with his
Apogee Full Range system:

http://forum.audiogon.com/cgi-bin/fr.pl?vaslt&1066703453

The Boz system appears to offer maximal flexibility for the number of bands; but it ties you into
using TacT's amps. The TacT RCS series has more flexibility when it comes to using different
amps because they can be fitted with analog converters; but the RCS is only 2-channel.

I don't see a "perfect" solution.

Greg's last post reminds me of a joke.

An engineer, a physicist and a mathematician are staying in three adjoining cabins at an old motel.
Michael,

The other old yarn is that you give an engineer and a mathematician the job of boiling water.
Each is confronted with the exact same situation; a kitchen with a saucepan in the cupboard and
a stove. The engineer goes first, gets the saucepan from the cupboard, goes to the sink and fills
it with water, puts it on the stove, and turns the stove on.

When confronted with the same situation, the mathematician does the same.

Now the situation is changed, there's a saucepan of water on the inactive stove.

The engineer goes in and turns on the stove.

When the same is given to the mathematician; he goes to the stove, gets the pan, takes it to
the sink and dumps out the water, and places the pan in the cupboard; THUS reducing the
problem to one he has already solved.

Considering the algorithm as a Green's Function doesn't make it more complicated; it makes it EASIER!!!Perhaps, but only if you are already familiar with and comfortable with with Green's functions. And they also come in handy when trying to intimidate someone with your knowledge, as you were trying to do with Michel.

But suppose that you were to go to TacT and say, "please explain to me what you are doing, in as much technical detail as you care to, and don't try to spare me from any jargon". I'm willing to wager that Green's functions won't ever come up. And why is that? Because Green's functions and the conceptual framework that surrounds them, aren't regularly employed within the context of linear digital signal processing within which TacT deals primarily. Traditional linear system theory and Fourier analysis serve that domain nicely and sufficiently. Yes, of course there is overlap and commonality, but they don't make things easier if the existing tools already do a good job of that.

So no, I don't agree that in this case, Green's functions make things easier; rather, they introduce additional conceptual complexity.

Perhaps, but only if you are already familiar with and comfortable with with Green's functions. And they also come in handy when trying to intimidate someone with your knowledge, as you were trying to do with Michel.
Michael,

No - I'm not trying to imtimidate Michel. He insinuated that those on the TacT forum were
more knowledgeable about the TacT system. Having researched the TacT systems thoroughly,
reading much of TacT's documentation and asking them questions, as well as following the
TacTUsersGroup, and an even better group, TheRealTacTHackersGrroup; which ultimately
culminated in setting up my own TacT system; I was trying to justify my own bona fides
when it came to the TacT system by giving an explanation of how it worked. [Michel claimed
that there were people at TacTUserGroup that actually understood the product. I think I can
make that claim as much as they can; although I wouldn't hold a candle to Boz.]


Traditional linear system theory and Fourier analysis serve that domain nicely and sufficiently. Yes, of course there is overlap and commonality, but they don't make things easier if the existing tools already do a good job of that.

So no, I don't agree that in this case, Green's functions make things easier; rather, they introduce additional conceptual complexity.

I'll grant that TacT probably wouldn't explain the operation in those terms; but I'm much more
accustomed to working with multi-dimensional problems. When I see an impulse generated
at one point in space, and the response recorded at another point in space - Green's Functions
is just naturally what comes to mind. I use Green's Functions all the time.

You don't need all the power that the Green's Function provides; and you don't get the full
Green's function because you aren't interested in the response at points other than the location
of the microphone; and you're not interested in any other forcing function locations other than
the locations of the drivers.

I think a Green's Function approach makes a nice way to explain it. Perhaps my
bias is due to familiarity. After all, I use a Newton-Krylov solver to invert a 2x2
matrix. :)

I have to agree with Michael here... this seems to be (on the surface) a simple matter of applying the inverse of the (room/speaker) filter to the original waveform. This filter is determined by analyzing the measured impulse response at various seating positions against the original signal. Fourier transform functions are commonly found in today's processor instruction sets (as a macro instruction).

Now, we can argue about whether an audio system is actually linear (it's not) but IMO a linear approximation is good enough.

I have to agree with Michael here... this seems to be (on the surface) a simple matter of applying the inverse of the (room/speaker) filter to the original waveform. This filter is determined by analyzing the measured impulse response at various seating positions against the original signal. Fourier transform functions are commonly found in today's processor instruction sets (as a macro instruction).

Now, we can argue about whether an audio system is actually linear (it's not) but IMO a linear approximation is good enough.
Greg,

If you limited that to a measured impulse response at a single location; the seating position; I
might agree.

However, once you start introducing other locations in the room; then you definitely are not
in a single-variable domain anymore. If you are attempting to correct multiple points in the
room; then you don't have a unique solution anymore. You're doing some type of optimization
problem then.

I'm not trying to imtimidate Michel. He insinuated that those on the TacT forum were
more knowledgeable about the TacT system.Well heck, if you want to take his claim that personally, I can't help it, but I hardly think that's what he was "insinuating." My gosh, you admitted less familiarity with the 2.2x system than with the 2.2XP. So isn't it conceivable that Tony Knight and others on the forum might be more familiar than you with potential bugs in the 2.2x? Was Tony Knight simply wrong when he said that "Tact is aware of the delay problem but, like so many other 2.2X problems, it has yet to be addressed." (http://tech.groups.yahoo.com/group/TacTAudioUsersGroup/message/19715) It's not like the 2.2x was bug free; even Peter Lyngdorf conceded that. I was a relatively regular reader of the Yahoo group awhile back, and I was impressed by the abilities of some of the more hardcore hackers.

Well heck, if you want to take his claim that personally, I can't help it, but I hardly think that's what he was "insinuating." My gosh, you admitted less familiarity with the 2.2x system than with the 2.2XP. So isn't it conceivable that Tony Knight and others on the forum might be more familiar than you with potential bugs in the 2.2x? Was Tony Knight simply wrong when he said that "Tact is aware of the delay problem but, like so many other 2.2X problems, it has yet to be addressed." (http://tech.groups.yahoo.com/group/TacTAudioUsersGroup/message/19715) It's not like the 2.2x was bug free; even Peter Lyngdorf conceded that. I was a relatively regular reader of the Yahoo group awhile back, and I was impressed by the abilities of some of the more hardcore hackers.
Michael,

Yes; frustrating week - and it shows.

I said that I was not as familiar with the 2.2x as I was with the 2.2XP which
I have. I'm aware that the 2.2x wasn't bug-free.

However, failing to correct for the processing time differences in the two bands,
while I know the 2.2x will correct for a spatial displacement of the subwoofer
relative to the mains; seemed too much like "guilding a lilly". I'd have to take
that flaw with a big grain of salt. Saying that someone on TacTUsersGroup
says so is not the degree of proof that I would like to see.

I have been using 2.2X for over a year and ETF5 for several years. One of the features of ETF is the ability to measure the distance between the speaker and the microphone when used in the Full Range frequency mode. When used in its Low Frequency mode, 20-125Hz, it is does not measure the distance between the speaker and the mic. This was annoying since I use stereo subs with my mains and I thought this would be an easy way to do a preliminary alignment.

Turns out, from my reading, that measuring a bass wave is not so straightforward. Because of the long wavelength the time window of the measuring device must be relatively large. The large window thus can include reflections and it can become impossible to to differentiate between the original wave and a reflected wave. Also because of the large wavelengths it can become difficult to determine what part of the the wave is being measured.

Further reading indicated the best way to align a sub and a main speaker was to measure the response. So now I don't worry about what Tact says but just use the Tact manual delays to find the best frequency response. This is time consuming but at least I know what the results are.

One Tact Yahoo poster said to use Cooledit which has the ability to filter an impulse response. One can export an ETF impulse to Cooledit, set the filter to 80-90Hz, look at the filtered impulse and look at the delay in samples or ms.

I asked Tact how the subwoofer delay was being calculated but never received a response.

Anyway from my experience measuring the distance of subwoofer is not so easy but I would be happy to learn of better methods.

I was perusing the Tact website which I have not done in some time and came across the following statement from this link for the 2.2XP:

http://www.tactlab.com/Products/RCS22XP/CorrectionTech.html

The [correction] filter is itself an impulse (in the time domain) which corrects both the time and frequency domain of the speaker-room combination.

This is the first time I can remember reading that the Tact correction filter actually corrects the phase response of the original impulse. It was well known that the original measurement impulse contained the time data and that the correction filter was applied to the original impulse, but Tact is now saying the correction filter actually makes corrections in the time domain. I have emailed Tact today to see if this is true for my 2.2X.

I do know the mathematics behind how the TacT works. It's really not difficult at all if you know Fourier Transforms.


I also do know about Fourier Transforms and I guess we have quite similar background (although I left the field a while ago).

Please don't misunderstand me, I am a TacT fan, I am using their units for about 6 years, I had/have the 2.2x, TCS 1, TCS 2, five S2150 and three S2150X. When you know the limitations of the product there are often ways to work around them.

I have been in regular contact over the years with many of the Yahoo forum members, yes that's true, on the forum there was a lot of controversy but the energy that some of users put in understanding the TacT units is impressive (some will even talk about reverse engineering). Please have a look to the TACS software (which was by the way sponsored by the official TacT distributor in europe), it is truly a nice piece of code and Boz himself was surprised the day he first saw it (I was there that day).

You can also wonder why these softwares (TACS, GV, Acourate) were developped... some users tempted by the adventure of active multiamping had the feeling they were too limited by the original TacT software.

However, these developments were a double edge sword, on the one hand they helped opening new possibilities (you will notice that TACS contains a 2150 firmware not available anywhere else, this firmware was actually developped by Boz to help them with this development of multiamping) but on the other hand this knowledge also revealed some issues here and there. This created heated debates to know whether these were bugs or features :-) At the end, when the new generation of hardware was around the corner, TacT took the decision to move all the computation back inside the units (as in the 2.2xp) which most likely close the door for future third party developments. Now we have no other way than trusting what is inside the box. BTW Lyngdorf took the same approach for their RoomPerfect system.

Michel

GGA---I am certain that TacT has been doing phase response correction from day one. (Whether they were doing it right is another matter.) Simultaneous magnitude and phase/delay correction is exactly why time domain correction is done in the first place. Otherwise you might as well just equalize.

Hi

Could the TacT/Boz owners on this forum share their impression of the system in term of sonics... Not the improvement brought by the Room Correction Software, rather how do they sound to you...

As an aside is SigTech and the Z-? currently in production?

Hello Michael,

There have been some lively threads at Tact Yahoo about time domain correction. Rereading some of these shows that you are correct by one definition:

http://tech.groups.yahoo.com/group/TacTAudioUsersGroup/message/24362

First off realise by reading the above link that it's NOT possible to
completely correct for time as well as freq. It would only be possible
over a very very small area and you would need your head clamped in
order to benefit.

The standard implementation of only correcting frequency and letting
phase sort itself out is hard enough to do correctly that today there
are only a very small number of commercial products available
(Tact/Lyngdorf/DEQX/Sigtech) which can do this at all and most hifi
firms will claim that the technology is impossible.

To go to the next level and to carefully introduce some distortion in
one area to reduce phase distortion in another is a very, very subtle
science and there are a) no commercial implementations of such a product
and b) even in research areas you have only Denis's DRC program and
Uli's filter generator that even attempt such a thing. I had a chat
with the new chief engineer at Lyngdorf audio and he does not even
believe that it is possible to make these time based corrections...

So basically be happy that you have frequency response correction at
all. It's not trivial to do even that!

So if designing a good RCS system is hard, then designing one which can adjust phase is much, much harder and few people even believe that it is *possible* much less understand how to do it.

AND ALSO:

http://tech.groups.yahoo.com/group/TacTAudioUsersGroup/message/23693?var=1&l=1

From theory a room pulse response can be split in two parts. One part is
minimum phase and the other part is excess phase. TacT does minimum phase correction only [my bolding]. Thus the excess phase is not corrected. The excess phase can be seen as an allpass filter where all amplitudes are transferred 1:1 but the phases are changed.

From theory the only correction here can applied by introduction of an
additional delay and the right phase inversion. The general opinion is that
excess phase correction is not possible (see e.g. description of Meridian
correction system). Anyway it introduces problems of dividing by zeros and
thus it can cause unstabilities.

The internal structure of the RCS as a multirate filter does not allow an
excess phase correction. So your goal is not achievable with the RCS.

Despite of negative opinions about excess phase correction IT IS POSSIBLE.
It requires some knowledge and a careful design. AFAIK there is no commercial system out there.

--------

The minimum phase describes a response with the shortest possible delays
necessary to reach a given amplitude response. So if you extract the minimum
phase part of a room response (e.g. by a homomorphic deconvolution = math
method) you have a signal that fully describes the amplitude response and
that has the shortest delays.

The inverse of such a minphase signal used as a correction filter corrects
also these shortest delays.

The excess phase is of course also measured. And the information is all
there for a possible phase correction. As said it is necessary to introduce
a bigger playbck delay with an excess phase correction. And so one reason
for not applying excess phase correction may be that you may loose lipsync
in combination with video. Another reason is tht the selected filter
structure makes it difficult. And finally a reason may be that it is not
well known how to handle it.
========================================

So it sounds like a matter of definitions. Tact does correct minimum phase but not excess phase. There's never a simple answer to anything.

Hello Frantz,

I use the 2.2X with the tape loop of my Placette active preamp. Setting the 2.2X in Bypass allows one to hear its sonic signature. In Bypass the signal goes through the complete Tact circuit but no corrections are applied but you can engage crossover, balance, and delay. There is a loss of transparency but it is not the end of the world.

However, once I correctly set up room correction the improvement in my room was so great that the loss of transparency is (for the moment anyway) of small concern. The goal would be to get that some frequency response but that would be quite a challenge.

I use Lavry Blue external DACs and ADC to replace the Tact's. One can chose any DAC or ADC to use with the Tact.

Sigtech is no longer being made. Z-Systems is alive and well and information can be found on their website (don't remember if they still make their eq). Lots of good information on the Robert E Green (REG) website, the TAS writer (and mathematician).

GGA, interesting posts. I'm frankly skeptical of their contents. One claim made is that full and exact phase correction is often not possible. That is indeed true. On the other hand, those posts claim that the RCS cannot do any excess phase correction due to their internal architecture; and it is that point on which I am particularly skeptical. It is possible to correct for nonminimum-phase behavior if you allow the RCS to introduce a strict time delay into the system (above and beyond its processing delay).

But at least it is clear that at least some phase correction is performed.

EDIT: Further reading of that thread makes it clear that the poster is not claiming that excess phase correction is never possible; indeed, he apparently has some software to compute the necessary corrections. He's only claiming that TacT doesn't do it. I'm still surprised by that, but as I don't own a unit I defer to those who do.

I also do know about Fourier Transforms and I guess we have quite similar background (although I left the field a while ago).

Michel,

Actually, signal processing isn't my field of expertise at all. The expert on
signals here is really Michael Grant. I have a rudimentary familiarity of
signal processing from unfolding the instrumentation response from
experimental data.

My background is actually nuclear physics, and computational physics.

GGA, interesting posts. I'm frankly skeptical of their contents. One claim made is that full and exact phase correction is often not possible. That is indeed true. On the other hand, those posts claim that the RCS cannot do any excess phase correction due to their internal architecture; and it is that point on which I am particularly skeptical. It is possible to correct for nonminimum-phase behavior if you allow the RCS to introduce a strict time delay into the system (above and beyond its processing delay).
Michael,

I think we share similar concerns. Although I don't have a detailed familiarity of
the actual algorithms implemented by the TacT RCS; I, like you; am skeptical of
some of the claims.

It would seem rather straight-forward to solve the delay problem by the
introduction of a time delay into the system. The RCS is after all meant for
2-channel applications; so it doesn't have to worry about syncing with a video
stream, for example.

The RCS can take all the time it needs - the listener is never going to know.

I'm skeptical that a device that's correcting the in-band temporal behavior of its
two pass-bands; would then turn around and introduce a large shift in the
timing between the two pass-bands.

The in-band time correction would be "guilding a lilly" in that case; and, as you
point out; there's no need for this inter-band timing difference when a delay
is all that's needed to accomodate the processing needs.

The all-digital TCS/Boz system brings some new issues that are not encountered in conventional analog systems.

Mixing speakers with different efficiency will bring out an issue that most people probably would not think about: Since the system is all digital, the dynamics of the whole system will be limited to the dynamics of the least efficient speaker! When the system is calibrated, the maximum level will be set such that 100% volume is 100% power to the least efficient speaker. (Big problem with the Magnepan CC3 which is ~9dB less efficient than a biamped MG20.1. I had to remove the CC3 from my system).

When purchasing TacT/Boz you'll need a lot of patience. Four of my five Boz amps had cosmetic and functional issues out of the box. (Yes, I purchased them from an authorized dealer). Now 3 months later, I'm still waiting for the last two amps to be fixed... That just sucks for a $30k purchase... :mad:

Peter

Peter I am so sorry to hear about this. No doubt about it shipping damages are a pain in this business. In retrospect your dealer should have staged the delivery so that the extra heavy BOZ216 came in it's own shipment. It's like having a loose cannon on the ups truck and most likely the culprit of the damage to the 2200 modules, it is a heavy S.O.B.

Ups is very uncooperative when damaged products are involved. If you order a Fujitsu plasma and your dealer does not check it during the first 15 days of delivery, and say it is cracked, the dealer owns it. That happened with 2 plasmas at a place where I worked last.

That being the case the tact system should be at the core of any serious multichannel surround setup, no doubt about it.

Peter I am so sorry to hear about this. No doubt about it shipping damages are a pain in this business. In retrospect your dealer should have staged the delivery so that the extra heavy BOZ216 came in it's own shipment. It's like having a loose cannon on the ups truck and most likely the culprit of the damage to the 2200 modules, it is a heavy S.O.B.

I would be understanding if it was shipping damange. Not so. FYI, the problem is ironically with the light 2200s (20lbs). The heavy 216 (80lbs) and TCS were flawless from day one!!!

Two of the 2200s had cosmetic defects from the factory. (Blemishes in front panel, one of the unit had a nut GLUED with Epoxy resin on the bottom!!!)

Two of the 2200s had functional problems. One unit had a dead left channel, the other one reports timeout problems, messing up the whole system.

When I sent in the unit with the dead channel for service (it was cosmetically flawless), it came back with THE FRONT PANEL SCRATCHED. The original problem was fixed, but instead it had a new problem: It would only power on every second time... 1 functional bad => 1 cometic bad + 1 functional bad

With all this waiting, it really feels very unprofessional of TacT...

Our home theatre is "down" since July when I sold my 9 Parasound JC-1s. It was supposed to go live in October when I received the TCS/Boz. Now it's still down... No movie in the Nielsen house since early fall... Waiting to get the Boz units fixed...

Did I say it sucks?!

Once I've solved all the problems, I may consider selling everything (due to bad after taste with all the problems I've gone through). If somebody wants to avoid problems, let me know. I will sell you the TCS,216, and 5 2200s for the same amont I paid. You will save all the agony an pain of getting brand new units fixed/replaced...

I feel that this is the worst purchase / most costly mistake I've ever made in the home theatre area...

Now, let me point out that I'm coming from Parasound, where 14 of 15 units arrive PERFECT out of the box, or 8 perfect JC1s out of 9. It is quite a chock to get 4 bad Boz2200 out of 5. (Quiz: The JC1 is $3500 and weighs 80lbs. The Boz 2200 is $3000 and weighs 20lbs. Which one should arrive cosmetically perfect?)

Peter