If you needed _4_Hz in room (but could pick the room) how would you? - Page 2 - AVS Forum
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post #31 of 58 Old 08-02-2013, 03:09 PM
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Bosso,

That's a good overview of your approach. However, somehow there's been some error in manipulating the in room measurment of frequency response.


Examining post #24, using the the purple trace, and comparing it to post #28, with the black trace, one of the two (or perhaps both, but not likely) submitted measurments has been incorrectly generated somehow along the process.


Examining the animated spectral room measurement, would lead me to believe the black trace FR, coincides with the spectral graph. Consequently the purple trace would be way off. But I have no idea which one is wrong. Bosso can shed some light on this?

I'm guessing something clearly got shifted upon generating these images. I know you've mentioned you extrapolate from one, to create another, or something similar.

These freqs/amounts are all approx., in rough comparison;

Black trace below, as compared to the Purple trace;
1.) Peak of bottom @7hz, whereas the purple trace was @5.5hz

2.) Ripple @18hz-19hz, the purple trace was @12hz

3.) Peak @30hz, the purple trace was @17hz-18hz

4.) Dip @ 48hz-50hz, the purple trace was @27hz-29hz

5.) Small scallop @75hz, the purple trace was @38hz

6.) Peaks and Dips onset @90hz, the purple trace was @49hz


For those reading, remember, black trace is post #28, purple trace is post #24


Thanks


Also, I too own and love Oppo. In my current primary rig, I can't do without the amenities my Pre/Pro allows me. But I entirely understand the quest for a minimalist, extended, and most importantly transparent head end control. I've used custom Alps dual mono attenuators, custom direct analog outs w/variable output control. That was a revelation. This mammoth Denon CD player w/variable outs right into the amps! That's a quarter century ago.

For now, I'm content with my extension ~8-9hz. The structural noise components can be an huge, scary issue with some material. I mean it's truly impactful. I contemplated tactile transducers, but lord, it's all there ... in spades! If I can resolve the structural noise associated with the deepest effects, perhaps I may pursue more extension.

The tactile transducers* may allow for lower playback levels of the deep stuff. I know CraigJohn speaks highly of his.
*They'd absolutely need to be coherent in the time/signal alignment, with judicious level control, .. just like every sub system smile.gif


Thanks

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post #32 of 58 Old 08-02-2013, 03:15 PM
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Since we turned the page, this will help ...
Quote:
Originally Posted by bossobass View Post






http://picasion.com/i/1VXeB/

[/quote]

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post #33 of 58 Old 08-02-2013, 05:48 PM
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Originally Posted by FOH View Post

Bosso,

That's a good overview of your approach. However, somehow there's been some error in manipulating the in room measurment of frequency response.


Examining post #24, using the the purple trace, and comparing it to post #28, with the black trace, one of the two (or perhaps both, but not likely) submitted measurments has been incorrectly generated somehow along the process.


Examining the animated spectral room measurement, would lead me to believe the black trace FR, coincides with the spectral graph. Consequently the purple trace would be way off. But I have no idea which one is wrong. Bosso can shed some light on this?

I'm guessing something clearly got shifted upon generating these images. I know you've mentioned you extrapolate from one, to create another, or something similar.

These freqs/amounts are all approx., in rough comparison;

Black trace below, as compared to the Purple trace;
1.) Peak of bottom @7hz, whereas the purple trace was @5.5hz

2.) Ripple @18hz-19hz, the purple trace was @12hz

3.) Peak @30hz, the purple trace was @17hz-18hz

4.) Dip @ 48hz-50hz, the purple trace was @27hz-29hz

5.) Small scallop @75hz, the purple trace was @38hz

6.) Peaks and Dips onset @90hz, the purple trace was @49hz


For those reading, remember, black trace is post #28, purple trace is post #24


Thanks


Also, I too own and love Oppo. In my current primary rig, I can't do without the amenities my Pre/Pro allows me. But I entirely understand the quest for a minimalist, extended, and most importantly transparent head end control. I've used custom Alps dual mono attenuators, custom direct analog outs w/variable output control. That was a revelation. This mammoth Denon CD player w/variable outs right into the amps! That's a quarter century ago.

For now, I'm content with my extension ~8-9hz. The structural noise components can be an huge, scary issue with some material. I mean it's truly impactful. I contemplated tactile transducers, but lord, it's all there ... in spades! If I can resolve the structural noise associated with the deepest effects, perhaps I may pursue more extension.

The tactile transducers* may allow for lower playback levels of the deep stuff. I know CraigJohn speaks highly of his.
*They'd absolutely need to be coherent in the time/signal alignment, with judicious level control, .. just like every sub system smile.gif


Thanks

Hi FOH,

Neither of the traces coincides with the posted Dig vs Mic'd SL caps, but it sure is a good thing to see someone actually reading the data correctly. smile.gif

Here's a comparo of the mic'd v digital scene of the Red Dragon crashing to earth in HTTYD (NOTE: The 2 caps don't need to be labeled as the direct digital cap shows the 60 Hz hum):

http://picasion.com/i/1VZAa/

Here's the actual FR when that cap was done, for analysis, scaled onto the SL cap in linear scale to match the cap:



The post you quoted and commented on was done as my time allows. I tend to grab from any number of in-room responses and comparo graphs that have been done over the years and with slightly varying FRs from many different systems I've had set up as well as SL caps done with varying spectrograph settings.

As you know, I've been over most of this stuff in detail for a decade now, so the search function might provide more detail than this thread. wink.gif

The most pertinent thing about this thread is that I've chosen to share my formulas for ref response in any given size listening space. This came about after about a zillion requests from members in PM regarding what system they should consider for their room that is 'X' size, open/sealed/semi-open, primarily for 'Y' source, listened to generally at 'Z' playback levels... etc. The formulas I posted are aimed directly at the OP title )"... 4 Hz in-room...") and they are sure fire and tested.

Regarding the new Oppo flagship, it has distance settings, trim settings, level calibration setting, plenty of crossover choices and enough voltage output to be able to setup, calibrate and drive any system. The only thing it lacks is so-called "auto-EQ", which, after exploring extensively, I'm not a big fan of.

I use a digital outboard PEQ for the front 3 speakers (currently 3 in, 6 out, bi-amped), but have found that the Oppo tweaks and room treatments give a much better result for the surrounds and surround back speakers than PEQ.

The 105s power supply, chipset/boards, preamp and DACS are the best value in sound fidelity and that's not just my opinion. Of course, the key in this thread is in-room to 4 Hz. Countless in-room FRs posted on AVS over the years have included the errant comment "I don't have any room gain below 10 Hz". There are 2 things wrong there, 1) they didn't have accurate enough measurement hardware and 2) they weren't feeding their systems much of anything below 10 Hz.

My measurement hardware is flat to 4 Hz and the signal chain is flat to 3 Hz:



The top (flattest) trace is the Oppo plus my analog signal shaper. The middle trace is the current signal as it reaches the drivers (Oppo => Signal Shaper => Amplifiers), which is right at -3dB @ 3 Hz and the bottom trace is the result of switching out the amplifiers to a different model.

As far as the difference between the Oppo direct vs through the Onk AVR, as I said, the only thing missing is Audyssey, which I didn't use anyway. Here's a close mic and in-room with both signal chains. I get +4dB at 4 Hz and +6dB @ 3 Hz using the Opoo direct vs with the Onk in line:

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post #34 of 58 Old 08-03-2013, 01:12 PM
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Quote:
Originally Posted by bossobass View Post

... it sure is a good thing to see someone actually reading the data correctly. smile.gif

I'd enjoy discussing the other aspects of your post too. But one of those FR graphs you submitted has been manipulated, and it's not a small amount;

Black trace peak @30hz, ............the purple trace was @17hz-18hz

Black trace dip @ 48hz-50hz, .....the purple trace was @27hz-29hz

The above are in addition to the other points I outlined in the previous post.


Like many here, I examine acoustic measurements all the time. The differences in those two FRs aren't attributable to "slightly varying" as you said. You'll see if you look closely.

This is merely a heads up pointing out what happened, no ill will here. Similarly, I don't believe you possess any malicious intent in the submitted mistake.


Thanks

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post #35 of 58 Old 08-03-2013, 03:25 PM
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Quote:
Originally Posted by bossobass View Post

The post you quoted and commented on was done as my time allows.

As was my astute analysis wink.gif

Quote:
Originally Posted by bossobass View Post

The most pertinent thing about this thread is that I've chosen to share my formulas for ref response in any given size listening space.

What's relevant to some, may not be to others. Myself, it's the room, and the overwhelmingly dominant manner in which it influences both our experience, and our measuring. That's what I cull from various contributions, yours included. Fortunately for us, we experience our systems sound in a manner entirely different from the way a measurement mic captures sound. Psychoacoustic masking, and other discrimination effects really impact our experience.

But even though that's what's of interest to me, I can appreciate you sharing your detailed approach in this thread, or any thread. I just hope those that can benefit the most can find it here.


Also, you're spot on wrt Oppo. Some may think $1k+ is expensive (and as I type this, it is expensive), but the value is off the chart. Oppo offers world class performance regardless of price.

About PVG/room gain, I'm not familiar with anyone claiming they it doesn't happen/they don't enjoy it's benefits. Although it's not surprising someone would claim anything, I'm not familiar with what you're referring to. I do remember the discussion about Geddes claiming something bizarre, but he never shared those thoughts here, and I don't remember anyone saying their rooms don't possess the phenomena. As you know, the physics involved doesn't pick and choose who gets what. I know we disagree on how the boundaries interact to elicit said benefits, but that's another discussion.

As to your bandwidth/extension, .. one the measuring side, or playback side, I'm sure it's world class. Many would be wise to follow your recommendations for prudent examination of their signal chain.

Regarding Audyssey, I'm coming around to it's benefits. Certainly one has to be careful and analyze what it's doing before and after. But the top model XT32 two channel approach is outstanding at one aspect in general; ... the modal region from Fs to the upper range of the subwoofer range. For whatever reason, this seems to be Audyssey's wheelhouse. The "power" region ... 60hz to about 200-300hz. Anyway, it would seem it's quite adept in that regard, in my experience. Maybe others haven't had a similar experience, my two cents.


Good stuff

All the best

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post #36 of 58 Old 08-03-2013, 10:00 PM
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Quote:
Originally Posted by bossobass View Post

Thanks Abraham for the kind words and consistently good posting. It would be nice if you could also post some details of your system, on which you did a superb job. I'm sure your playback results are just as good. cool.gif

Here are the brass tacks:

1) Signal chain: Flat to 3 Hz. Without this, there will be no success <10 Hz.

Here are some versions of signal chain using the required L/T configuration accomplished through various hardware options from the player to the AVR/Preamp to the signal shaper to the amplifier. All have a 2nd order LPF @ 250 Hz in line. NOTE The light blue trace is through a DCX using only a shelf filter, as some suggest using. Obviously, there can be variations of that single curve based on what AVR/Amplifier is used:



It should require no comment as the graph tells the story of how the final response will be influenced by what signal chain is employed.

2) Driver displacement: .01 liters per cubic foot of listening room. Example: 2000 cubes = 20 liters of displacement minimum. That requirement's met by employing 3 UXL-18s, 4 SI-18s, 6 SI 15s, 7 Dayton HO-18s, 6 Dayton 15 Ultimax, 7 SA-15s, etc.

Alignment: Sealed. Ultimate "efficiency" <20 Hz is determined by box size, but must be balanced with excursion protection, which is an investigation, like the signal chain investigation, requires careful thought and final testing and will be dependent on the parameters of the driver chosen vs the Vb chosen with caution being exercised against the need to alter the signal chain in a way that eliminates the bandwidth of interest.

Amplification: Approximately 5W peak per cubic foot of listening space. This is based on a system designed with proper signal shaping to mate the system with the room. This requires a fairly accurate measurement of the naked system response compared to the system response in-room, from which comparison the Room Gain profile may be determined. The input signal may be altered to affect a new system FR that's designed to mate the system so that the result is a flat response to the desired frequency. . It's assumed that the amplifier(s) will be supplied by the proper AC and that the system will be operated only by responsible persons after proper setup, calibration and limits testing in-room using the actual program source of interest.

Transmission loss calculation: A debatable subject when speaking about <100 Hz, but the losses will obviously vary by construction method. This is the part of the equation that most folks confuse with "a sealed room".

All of my own imperial evidence from 10 years of measuring suggests that how sealed a room is, regarding air tightness, is largely irrelevant. Contrary to conventional wisdom, a drivers motion does not affect a change in the ambient pressure of a room. Rather, the drivers motion creates a sound pressure wave that travels through the air in the room. The air in any particular room may vary in temperature and/or humidity which both effect the behavior of the pressure wave, but the differences in that variable are unmeasurable unless one lives in a tent in the woods in the mountains or some similar unrealistic and irrelevant extreme.

The gain from the rooms boundaries increases as frequency decreases because the longer the sound wave vs the distance to boundaries, the more interference becomes constructive and conversely, the less the chance reflections can be destructive. Using this premise to explain 'room gain', a completely enclosed room may actually have less room gain than one which is partially open. The pertinent factors are; Item 1) above, item 2) above, transmission losses in the bandwidth of interest, the coincidence of resonant frequencies of the structure with the BW of interest and the placement of the system within the listening space.

Transmission losses through the boundaries will determine how much gain you realize at any given frequency, assuming all of the above have been considered and executed optimally. Obviously, if half the pressure wave is lost through the boundary to outside the room, then only 1/2 can be reflected back into the room to continue reflecting as it decays.

In any case and regardless of one's personal opinions regarding the mechanics of the phenomenon known as "Room Gain", measured responses of systems taken outdoors at GP vs in-room from Ilkka, Ed Mullen, Josh Ricci, MKT, notnyt and myself in rooms ranging from <2000 cubes to >4000 cubes show that "Room Gain" begins around 30 Hz and continues to increase in a similar pattern as frequency decreases down to the signal chain rolloff, which then dominates in-room response at the lowest octaves.

Using 2000 cubes listening room and DIY boxes loaded with 4 SI-18s (21.2 Liters), MiniDSP, a "clone" amplifier, the system will cost < $2500. It will meet the 4 Hz in-room response requirement at a properly calibrated reference level in any room that size.

In my case:



ROOM: 3500 cubes
DRIVER DISPLACEMENT: 36 Liters (Formula suggests: 3500 X .01 = 35 Liters)
SIGNAL CHAIN: (FR shown in graph) Oppo BDP-105 as pre/pro/player ==> SEQSS analog signal shaper =>> clone amplifier version (2)
AMPLIFICATION: 2 amplifiers, each @ 9KW peak (18KW total). Formula suggests: 3500 cubes X 5W = 16,500W peak.
IN-ROOM results: (shown in graph).
Playback Accuracy at Reference Level graphed from the LP:

http://picasion.com/i/1VXeB/

This is the basic formula. It will work for any room. If more output is desired, more displacement/amplification is required, which is scaled at +6dB per 2X. The formula can be deviated from only if the desired bandwidth is truncated on the low end by design or by deviating from any single point of the formula.

Only the best from Bossobass Dave! smile.gif

This post should be required reading for the ULF-tard in all of us. biggrin.gif

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post #37 of 58 Old 08-04-2013, 08:13 AM
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Quote:
Originally Posted by FOH View Post

I'd enjoy discussing the other aspects of your post too. But one of those FR graphs you submitted has been manipulated, and it's not a small amount;

Black trace peak @30hz, ............the purple trace was @17hz-18hz

Black trace dip @ 48hz-50hz, .....the purple trace was @27hz-29hz

The above are in addition to the other points I outlined in the previous post.


Like many here, I examine acoustic measurements all the time. The differences in those two FRs aren't attributable to "slightly varying" as you said. You'll see if you look closely.

This is merely a heads up pointing out what happened, no ill will here. Similarly, I don't believe you possess any malicious intent in the submitted mistake.


Thanks

I had some time this morning and sure enough, I found the mistake. I set the sig chain and LP traces on a fresh blank graph but skipped the step of the horizontal scaling. The traces are correct, they're just stretched out of scale from left to right.

It took a bit of head scratching after glancing at your comments because I not only have I never entertained the thought of manipulating graphs (no sense to that at all), to the contrary, it's a very tedious and painstaking process to get the transfers and/or overlays as precisely correct as the software and human ability allow for.

I corrected the traces and included the other trace. The system trace is smoothed, the other trace is not, but they are not the same measurement and, as I noted earlier, neither of them is the FR used when the SpecLab comparo was done.

Here's the corrected version and the other FR graph you cited below, scaled in BOTH directions and an additional graph with appropriate caution noted below. tongue.gif



I also threw a handful of traces on a blank graph for future reference to remind that I have countless measurements of dozens of subs placed in infinite positions relative to the mic. So, you can't always look for room influences to reconcile 2 traces in my posts. Where 1 shows a dip, the other may show a peak, etc. These days, I might just grab anything that''s convenient from any # of folders.

In this case, there were recent and on a flash drive. I just wanted to get the sig chain and LP traces on the same graph. The sig chain loopback was on a graph that went from 2 to 500 Hz and the LP trace was only to 100 Hz and both were transferred to a graph with horizontal scale from 5 to 200 Hz.. I (too) quickly placed them on the same graph and there ya go...

Thanks for the catch.
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post #38 of 58 Old 08-04-2013, 08:18 AM
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Originally Posted by FOH View Post


About PVG/room gain, I'm not familiar with anyone claiming they it doesn't happen/they don't enjoy it's benefits. Although it's not surprising someone would claim anything, I'm not familiar with what you're referring to. I do remember the discussion about Geddes claiming something bizarre, but he never shared those thoughts here, and I don't remember anyone saying their rooms don't possess the phenomena. As you know, the physics involved doesn't pick and choose who gets what. I know we disagree on how the boundaries interact to elicit said benefits, but that's another discussion.

Good stuff

All the best

Originally Posted by gedlee

"Room gain" is one of those misnomers that is true in theory but never found in practice. It comes from the fact that any sealed enclosure will have a mode at DC, which is to say that it can maintain a static pressure. But no room is perfectly sealed. My room, being sound proof, has sealed doors and as many leaks as possible are sealed, but it still has to have HVAC, so its always leaky. In theory the DC mode causes a 1/f pressure rise, but when there is leakage, this levels off below some frequency. The frequency and level depends on the rooms volume and the leakage.

Very small rooms like cars can see this rise, but larger rooms like home listening rooms will always have too much leakage to have any real gain. I don't see it in my room and I've never seen it in any listening room, but I have seen it in cars. By the time you get to a van or SUV size its gone.
________________________________________________________

Otherwise, I'm referring to folks who measure their response, see the nose dive below 10-15 Hz in the result and blame the room instead of the sig chain/measurement rig. I've read it many times.
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post #39 of 58 Old 08-04-2013, 08:50 AM
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Thank you so much to those who have contributed to this topic, I've certainly learned a lot from this single thread. I apologize in advance for my ignorance as I don't mean to hijack, but does the Oppo 103 have a higher rolloff than the 105? I've looked at the specs and have read through quite a few pages of information but can't seem to find anything on the subject. Again, than you all for posting as it's been a very informative read.
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post #40 of 58 Old 08-09-2013, 06:30 AM
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Quote:
Originally Posted by bossobass View Post

2) Driver displacement: .01 liters per cubic foot of listening room. Example: 2000 cubes = 20 liters of displacement minimum.
I don't think I've ever seen it summed up that way, but is a nice shorthand way to calc requirements. When my other pair of FTW21's arrive, I should have about 25L of capacity (one way Xmax) in 1830cf so it should be enough.
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post #41 of 58 Old 09-11-2013, 06:30 AM
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Quote:
Originally Posted by bossobass View Post

2) Driver displacement: .01 liters per cubic foot of listening room. Example: 2000 cubes = 20 liters of displacement minimum. That requirement's met by employing 3 UXL-18s, 4 SI-18s, 6 SI 15s, 7 Dayton HO-18s, 6 Dayton 15 Ultimax, 7 SA-15s, etc.

Your formula is very precise. My new home theater (2000 ft³) will have 18 x Peerless XXLS12 in closed boxes which results in a Vd of 23 l.

The simulated max SPL at 6 Hz is 99 dB. I measured the room gain at the listening position and it adds a nice +28 dB at this frequency. So I get 127 dB @ 6 Hz. Going down to 3 Hz it results in about 115 dB = reference SPL. smile.gif
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Originally Posted by FoLLgoTT View Post

Your formula is very precise. My new home theater (2000 ft³) will have 18 x Peerless XXLS12 in closed boxes which results in a Vd of 23 l.

The simulated max SPL at 6 Hz is 99 dB. I measured the room gain at the listening position and it adds a nice +28 dB at this frequency. So I get 127 dB @ 6 Hz. Going down to 3 Hz it results in about 115 dB = reference SPL. smile.gif
Graphs and pics or it didn't happen wink.gif lol biggrin.gif
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post #43 of 58 Old 09-11-2013, 12:52 PM
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Graphs and pics or it didn't happen wink.gif lol biggrin.gif

Ok, here we go. smile.gif

Room size: 6 x 4.8 x 2.2 m

In my experiment there were two subwoofers on the front wall (1/4 of width and 1/2 of height). On the back wall there was 55 cm of porous absorbent.

Here are the measurements at different distances to the front wall. The black curce labled with the german word "Nahfeld" is the nearfield frequency response. As you can see the subwoofers were closed boxes (falling at 12 dB/Oct).



The next graph shows the difference between nearfield and 3m curves. I chose this position, because it is the middle of the room. At this point the length mode has no peak and doesn't influence the gain.
As you can see there is a fine 12 dB/Oct rise to lower frequencies starting right below the first length mode (27 Hz). Please ignore the 4 dB-offset, since it depends on how I align the nearflied measurent to the other curves (which is not trivial). The gradient is independent to alignment.



The walls of my room consists of calcareous sandstone. Floor/ceiling are made of concrete. Where I live this is a common building technique.
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post #44 of 58 Old 09-15-2013, 07:54 PM
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Ok, here we go. smile.gif

Room size: 6 x 4.8 x 2.2 m

The next graph shows the difference between nearfield and 3m curves. I chose this position, because it is the middle of the room. At this point the length mode has no peak and doesn't influence the gain.
As you can see there is a fine 12 dB/Oct rise to lower frequencies starting right below the first length mode (27 Hz). Please ignore the 4 dB-offset, since it depends on how I align the nearflied measurent to the other curves (which is not trivial). The gradient is independent to alignment.

The walls of my room consists of calcareous sandstone. Floor/ceiling are made of concrete. Where I live this is a common building technique.

Awesome work! Added to the RG profiles:



Yes, alignment of the close mic with the listening position curve is not trivial, but you've done a pretty good job, IMO and it matches with the theory I've been talking about:

1) RG starts around 30 Hz (+/-).

2) RG rate of increase is more dependent on transmission losses than room size.

What are the signal chain particulars (AVR, sub amps)?

(I'm guessing this is Nils? I'll get to your e-mail as soon as I get to them. Hope that's cool.)
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post #45 of 58 Old 09-16-2013, 05:46 AM
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Originally Posted by bossobass View Post

What are the signal chain particulars (AVR, sub amps)?

For my measurements I used the following components:

- soundcard: M-Audio Delta 44
- amplifier: Alesis RA-300
- mic: Behringer ECM-8000 (calibrated against professional microphone)
- mic pre amp: Behringer UB802

The final home theater will use an Onkyo PR-SC5507. I didn't measure its frequency response yet. Maybe I'll do this in the evening.
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(I'm guessing this is Nils? I'll get to your e-mail as soon as I get to them. Hope that's cool.)

Yes, everything's cool. It takes a few weeks until the room is drained and I can start building the subwoofers. So I have much time before my new home theater gets ready. smile.gif
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post #46 of 58 Old 10-12-2013, 07:05 AM
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Today I measured the frequency response of my Onkyo PR-SC5507 and the Behringer Ultracurve DEQ2496.

But first I checked my measurement setup. The soundcard and microphone amplifier are -3 dB down at 3,2 Hz. For measurements with microphone this results in -3 dB @ 5 Hz. I have calibration files for both, only soundcard and soundcard + mic amp.



The signal was fed through "Balanced In" of my Onkyo. -3 dB is at about 3 Hz. The Behringer is a bit better in this regard at about 2,5 Hz. Together this gives me -3 dB @ 4 Hz.



I didn't measure the power emplifier, since it will get replaced when my bass system is build.
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post #47 of 58 Old 10-12-2013, 11:08 AM
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Quote:
Originally Posted by FoLLgoTT View Post

I didn't measure the power emplifier, since it will get replaced when my bass system is build.
If you've measured it with a microphone, ie post speakers, then you have already included the amp in your measurement.
If you want to measure the electronics alone, then directly into a soundcard via resistive divider (to not overload S/C) is what you need to do.
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post #48 of 58 Old 10-12-2013, 05:13 PM
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Quote:
Originally Posted by A9X-308 View Post

If you've measured it with a microphone, ie post speakers, then you have already included the amp in your measurement.
If you want to measure the electronics alone, then directly into a soundcard via resistive divider (to not overload S/C) is what you need to do.

Ok, maybe my statement was a bit misleading. Of course I will NOT measure the power amplifier WITH speakers to judge the amplifier. I don't measure this model now, because I don't use it later. smile.gif
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post #49 of 58 Old 06-09-2014, 11:56 AM
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Sorry to bump this old thread, I came back to it while referencing it on AVForum - it is very useful! smile.gif

The question I had was regarding the signal chain element of the above, and how Audyssey can be included.


If, for example, I was to find the cash for a Oppo 105 and a SEQSS signal shaper (or MiniDSP?), how would I integrate that with my Onkyo 818 with Audyssey XT32?


The Oppo 105 looks like it has HDMI Out and also analogue RCA(?) Outs for each channel (page 7 of http://download.oppodigital.com/BDP105/BDP-105_USER_MANUAL_English_v1.4.pdf).

The Onkyo has HDMI in but I can't see any individual RCA(?) In sockets (http://www.uk.onkyo.com/downloads/2/1/7/1/8/ONKYO_TX-NR818_datasheet_EN.pdf ).


Does this therefore mean that I would connect the 105 to the Onkyo with an HDMI cable, and connect the 105 to the SEQSS/MiniDSP with an RCA(?) cable?

How would Audyssey XT32 cope with that?


It would not be able to EQ below, I presume, the crossover point you chose between the speakers and sub, so would you run XT32 for, say, 80Hz and above, and then manually measure <80Hz and re-profile the response using the SEQSS/MiniDSP as required?


Apologies for what are probably dumb questions frown.gif
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post #50 of 58 Old 06-09-2014, 07:09 PM
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Quote:
Originally Posted by MemX View Post

Sorry to bump this old thread, I came back to it while referencing it on AVForum - it is very useful! smile.gif

The question I had was regarding the signal chain element of the above, and how Audyssey can be included.


If, for example, I was to find the cash for a Oppo 105 and a SEQSS signal shaper (or MiniDSP?), how would I integrate that with my Onkyo 818 with Audyssey XT32?


The Oppo 105 looks like it has HDMI Out and also analogue RCA(?) Outs for each channel (page 7 of http://download.oppodigital.com/BDP105/BDP-105_USER_MANUAL_English_v1.4.pdf).

The Onkyo has HDMI in but I can't see any individual RCA(?) In sockets (http://www.uk.onkyo.com/downloads/2/1/7/1/8/ONKYO_TX-NR818_datasheet_EN.pdf ).


Does this therefore mean that I would connect the 105 to the Onkyo with an HDMI cable, and connect the 105 to the SEQSS/MiniDSP with an RCA(?) cable?

How would Audyssey XT32 cope with that?


It would not be able to EQ below, I presume, the crossover point you chose between the speakers and sub, so would you run XT32 for, say, 80Hz and above, and then manually measure <80Hz and re-profile the response using the SEQSS/MiniDSP as required?


Apologies for what are probably dumb questions frown.gif

OPPO => HDMI out => Onk => HDMI in => Onk analog SW out => SEQSS (or MiniDSP) analog in => SEQSS (or MiniDSP) analog out => Sub Amp or plate amp analog in

Set up the Audyssey mic, run the program and done.

The OPPO analog SW out vs running through the Onk roll off difference is posted earlier in this thread. I've done both (using the Onk with thew OPPO 105 with HDMI and just the 105s analog out without the Onk) with good results.

The OPOO analog outs straight to amps for the subs and sats positively sounds better than through the Onk, but the OPPO has a global crossover (can't set separate X-over points for the fronts, CC, surrounds) and the Onk has Audyssey.

I opted for the shallower roll off of the OPPO and its clearly superior sound (used multi-channel SACDs and asked musicians with good hearing about the difference and the winner was hands down the OPPO).
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post #51 of 58 Old 06-10-2014, 09:13 AM
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I will continue the thread bump as this seems a relevant place to post my Qs on this subject as it's one I've been contemplating recently (i.e. what it would take to dive into single digits... this probably the conversation @MemX is referring to above). There are 2 things mentioned in this thread that I wonder if anyone can clarify. 

 

Firstly measuring signal chain rolloff, is it just a question of measuring each individual component and then adding up the result? If so, is there a cookbook for doing this? My take follows using my signal chain as an example which is;

 

PC via firewire -> Focusrite Saffire Pro 24 -> multichannel analogue -> Marantz AV7005 -> XLR -> Speakerpower SP1-6000 

 

Taking this one step at a time then....

 

I have some REW soundcard cal files, the focusrite is -3.7dB at 10Hz and -8.6dB at 5Hz and another device shows similar performance (an art dual pre) so clearly a problem at the 1st hurdle. 

 

 

However ISTR HPF on mic inputs are not uncommon which, if that is the case in my situation, then it's a correctable problem (whereas a rolloff on the output would necessitate a new audio device). The question therefore is how do I untangle the response of the mic input from the output? Is it just a question of finding another device that does not have such a rolloff and using that for the other side of the loopback?

 

The next step would be the processor outputs which I suppose means another loopback measurement but with the out being from the pre out instead of the audio device.

 

After that comes the amp, would this mean measuring the output with a multimeter when fed with various sine waves at different frequencies or some other approach?

 

Secondly there is the problem of room gain/transmission loss. Does anyone have a view on the transmission loss to be expected from a typical Victorian house in London? i.e. suspended wooden floor over a ventilated void & solid brick walls. I've seen other comments regarding typical US construction methods but I'm not sure how they might be expected to apply to the UK. My initial measurements involved overlaying a near field response against an unequalised in room response and seeing how the roll off compares, this suggests v little gain from 30Hz down except for a hump around 20Hz. My room is approx 1600 ft3 (13' 7" x 12' x 10'). 

 

 

Obviously I need to resolve the soundcard question above first but I'm still unsure what the best way to measure that effect is when it's not possible to measure outside first.  Perhaps I am simply not measuring deep enough to see a meaningful effect. Suggestions on how to proceed would be appreciated.

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post #52 of 58 Old 06-10-2014, 11:03 AM
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Quote:
Originally Posted by bossobass View Post

OPPO => HDMI out => Onk => HDMI in => Onk analog SW out => SEQSS (or MiniDSP) analog in => SEQSS (or MiniDSP) analog out => Sub Amp or plate amp analog in

Set up the Audyssey mic, run the program and done.

The OPPO analog SW out vs running through the Onk roll off difference is posted earlier in this thread. I've done both (using the Onk with thew OPPO 105 with HDMI and just the 105s analog out without the Onk) with good results.

The OPOO analog outs straight to amps for the subs and sats positively sounds better than through the Onk, but the OPPO has a global crossover (can't set separate X-over points for the fronts, CC, surrounds) and the Onk has Audyssey.

I opted for the shallower roll off of the OPPO and its clearly superior sound (used multi-channel SACDs and asked musicians with good hearing about the difference and the winner was hands down the OPPO).
Thank you very much, sir, that's most kind! smile.gif


So, if I am correctly understanding things, I can either:

- continue with the 818 as a processor and EQ device for the 80Hz and up range, purchasing a MiniDSP/SEQSS for Sub EQ duties, and just live with a higher roll-off.

- cut the 818 out of the loop entirely (for BD/CD/SACD playback) and use the Oppo's processing power, feeding to a MiniDSP/SEQSS then amp for subs, and feeding a 5 or 7 channel amp for Speakers, enjoying the benefits of less roll off and greater extension. (I would need to purchase an amp for the Speakers because I am using the 818 for that duty at the moment.)

I guess my fear is that the Oppo doesn't have an EQ solution for the speakers so that range might not sound as good as with Audyssey, but then your SACD experience would suggest it is more than fine without Audyssey!


So, what to do... at first glance it is Audyssey vs extension but if Audyssey is not needed with the 105, I wouldn't need the 818 apart from for radio duties, perhaps...

Due to the added cost implications of an additional amp I think I will have to try it with the 818 for the moment and see how it goes, but perhaps borrow an amp for the speakers and do a back to back listening test to see if I can measure any difference!

The Oppo 105 is not exactly a bargain either... lol, but I am not sure if the lower-spec models would suit. Probably not!


Thank you again smile.gif



EDIT: Sudden thought - (probably wrong lol): I guess I could use the 818 as a hub for the DVR / Radio / laptop inputs (if I used them) then do HDMI Out from the 818 and HMDI In into the back of the 105? The 105 would then deal with all disk media playback directly, leaving the 818 switched off, and the other sources would be selectable on the 818 and from there feed into the 105 and use it as a pre-amp?
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post #53 of 58 Old 06-10-2014, 11:55 AM
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The Oppo 105 and XSP-1 is no less then -1db @ 2hz... (according to my soundcard at least.)


So using these in the signal path is a good choice.

The DCX and cleanbox pro, not so much: -3db @ 5hz and -3db@8.2hz
But if you apply a 20hz 6db inverse shelf boost 12db/oct it goes to 2hz@-3db (which is a setting that I use):





Even though my amps roll off at 6-10hz, I still manage to get -5db @ 4hz from my Left, Right, Center.

My mic isn't professional or professionally calibrated so I wouldn't put too much faith into this last chart. (Is what it is.)
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post #54 of 58 Old 06-10-2014, 12:04 PM
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Four of these and one or two clones in an IB with a 105 would be a good "start" at aiming for 2-4hz.
That's what I would do if I were in your shoes.

http://www.parts-express.com/re-audio-xxx18-v2-4-18-cast-frame-dvc-subwoofer-driver-4-4ohm--268-8155
This driver is great because it has so much excursion.

Another good choice would be the SI 24 because it has lots of displacement and a good amount of excursion too.
http://stereointegrity.com/index.php?id=61

It's either that or fork out for a rotary woofer. Choice is yours to make wink.gif
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post #55 of 58 Old 06-10-2014, 12:44 PM
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Those two are not needed but will do the best with minimum drivers. I can get to 4 Hz without the Oppo.

AVR-Yamaha A830
amps-5 Adcom 555 in 850 watt monoblock mode
sub amp-Sanway FP14K
LCR-Dual stacked BFM DR-250's
Surrounds- Dual stacked BFM W10's
subs-12 SI 18's ported 6hz.
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post #56 of 58 Old 06-10-2014, 02:53 PM
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Some measurements

 

red = soundcard cal for my onboard line in/line out

yellow = focusrite saffire pro 24 line out to onboard line in

blue = focusrite saffire pro 24 line out to marantz av7005 pre out

green = marantz av7005 response only (i.e. delta between blue and yellow)

 

the AV7005 is in pure direct mode

 

The sum total being -3dB at 3Hz, -2dB at 4Hz, -1.3dB at 5Hz and -0.3dB at 10Hz (which is where my EMM-6 mic is calibrated to, by CSL). This seems to indicate my existing signal chain is good for 5-6Hz (unless I've made a mistake somewhere).

 

 

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post #57 of 58 Old 06-12-2014, 10:48 AM
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I took another measurement down to 5Hz at the listening position in my room & plotted that against the theoretical 12dB/octave rolloff to get a view on ULF gain in my room. This gives me the following

Click image for larger version

Name:	room_gain.JPG
Views:	122
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ID:	111249

NB: is there no way to insert a full size image now?

Last edited by 3ll3d00d; 06-12-2014 at 10:50 AM.
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post #58 of 58 Old 06-12-2014, 03:33 PM
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Quote:
Originally Posted by 3ll3d00d View Post
I took another measurement down to 5Hz at the listening position in my room & plotted that against the theoretical 12dB/octave rolloff to get a view on ULF gain in my room. This gives me the following

Attachment 111249

NB: is there no way to insert a full size image now?
You can once it has a home on the web, but not directly from the upload. If you click on the image and "copy image URL" you can paste it in-line like this:
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