Official DataSat RS20i thread. (Setup Tips, Questions,General Info, etc) - Page 12

Here's a little blurb. Link.

I have no doubt that ATI amps sound good, in whatever guise they are sold. I also get why bridged amps are necessary when higher power is needed than can be swung by a single-ended amp. But I always felt that if you could get sufficient power with a single-ended amp, that would be preferable to a bridge amp, all else being equal.

When two amp outputs are connected to the same load, in bridge configuration, several things occur:

--There are two noise sources added together, for a 3 dB higher noise floor. Presumably this is a non-issue since the preamp output noise will usually swamp out the amp's noise. Just stating for the record. The next items are more important.

--The output impedance doubles (damping factor cut in half).

--There are two sets of distortion components adding together. If they are identical, that's a 6 dB increase.

--Each amp sees half the speaker's impedance. This can often mean there's higher distortion. You can see this in Stereophile amp tests when they show power vs. distortion for 8/4/2 ohm loads. Example. Your 4 ohm speakers experience the distortion depicted in the 2-ohm curve.

All these factors are about the output stages and speakers, not about the balanced inputs where the common mode rejection helps kill induced hum/noise. That is indeed a benefit of fully balanced amps, but it is an equal benefit of single-ended amps with balanced inputs.

Many times in AVS Forums people have extra amp channels sitting idle, and want to bridge them "for more power." I tell them if the normal amp setup is never clipping, don't do it. Am I giving bad advice?

Thx for the link Roger.

Isn't there a difference between a fully-differential amplifier channel and a pair of bridged single-ended amp channels? something to do with a feedback loop? What you describe doesn't seem to match what's described at ATIs site regarding their "fully balanced" design.

Could you elaborate, please?

Dan
ATI specs.jpg 1077k .jpg file

The main difference is that in the fully balanced design the balanced input, allegedly, is split such that the + signal goes to the + amp and the - signal to the - amp. In other bridge amps they see a single-ended input with an inverter in the - path. This can be the case even if the input stage has a balanced input. Even the ATI amps have the inverter as it is needed when the input is single-ended. The way Bryston does this is that each amp's front end has + and - inputs. Drive both for differential sources, drive just one or the other for single-ended sources. The feedback path is conventional. See attached.

I looked at ATI's specs before I posted originally. I do not see any conflict.

Bryston_28-BSST_schematic.pdf 235k .pdf file
Edited by Roger Dressler - 2/12/13 at 10:50am

Isn't that canceled by the +6 dB power increase?

The distortion remains unchanged: Odd order distortion doubles, even order distortion cancels out.
However, it is very noteworthy that the noise floor does not remain unchanged. It will be higher since the dynamic range remains unchanged.
Edited by Peter Nielsen - 2/12/13 at 5:15pm

Yes, you are right. I should have not ignored the signal doubling!

Datasat have confirmed the Neo6 bug in the current software and will fix it with the next update. Great to see their quick action on this, albeit relatively minor, matter.

So did everyone here purchase the Dirac calibration kit or did you rent it/borrow it from your dealer? I would assume after of a few passes, it's no longer needed until you make a major change in the room.

Meaning you didn't purchase the Datasat offered Dirac kit? What did you purchase?

If your dealer will let you rent/borrow it, by all means. If they will run the calibration for you, all the better if you want to avoid the learning curve. But, if you are like many of us in this thread without a local dealer then you are on the hook to get the Dirac key and the kit. It worked for me as I like to be self-sufficient, so if I ever move furniture or change speakers I can now just use my own stuff to re-run Dirac as necessary.

I bought all my equipment separately from each and made my own "kit" (Earthworks M30 and a USBPre v.1, plus the dongle and my macbook pro running bootcamp/XP), and saved a little bit in the process, but if a dealer will give you a reasonable price on the whole set-up then I suggest you go that way to just make life easy.

By the way - I see you are in Jersey -- Is there a dealer there now? Up to a couple of months ago nobody was listed in the Northeast as a re-seller...

The datasat official kit consists of Usbpre2, Manfroto tripod, earthwork M30, cables, decent flight case. And in the uk a 2 day training course.

Dave, that's a lovely before and after example. I can not wait to get mine calibrated. My room treatments do well down to about 50hz but there is loads for dirac to control below 50hz

The official Datasat policy is now that the only way to get Dirac software is to purchase the installer kit in it's entirety. It should be noted that Datasat has to approve the sale as well.

Dan

Nice results, Dave. It sounds pretty similar to what I experienced (I didn't take waterfalls though).

NICE!!!!

Please show more.How about full range?

Have you tried moving the mic a few inches to see if the waterfall plot still looks similiar to your LP measurement?

Could you show some before and after impulse responses,windowed out to around 150ms?I'm interested in seeing early reflection levels.In your set-up though, they probably are already ideally treated.
Edited by StevenLansing - 2/13/13 at 3:48pm

Thanks:)

DATASAT EXPANSION CARD
We are pleased to announce the Datasat Expansion Card, which will unlock a whole host of new features on the RS20i audio processor. At the heart of this new card are two additional powerful DSPs to bring the total DSP power to 8 chips for the most powerful processing available.
The Datasat Expansion Card includes the following:
NEW DECODERS
The following new decoders are in addition to the existing Dolby Digital, DTS and DTS HDMA decoders.
Dolby Technologies
• Dolby Digital Plus NEW
• Dolby Pro Logic IIz NEW
• Dolby Pro Logic IIx NEW
• Dolby TrueHD NEW
DTS Technologies
• DTS Neo:X NEW
NEW SPEAKER CONFIGURATIONS UP TO 11.1
DTS Neo:X supports front wide and front height speakers (up to 11.1). Dolby TrueHD supports front height speakers (up to 9.1). The Datasat Expansion Card increases the number of speaker configurations to 11 plus phantom centre.
RS20i Speaker Configurations will include:
2.0 (L, R)
3.0 (L, R, C)
4.0 (L, R, Ls, Rs)
5.1 (L, R, C, Ls, Rs, Sw)
7.1h (5.1 + L height, R height) NEW
7.1w (5.1 + L wide, R wide) NEW
9.1hw (5.1 + L height, R height, L wide, R wide) NEW
7.1 (L, R, C, Ls, Rs, Lbs, Rbs, Sw)
9.1h (7.1 + L height, R height) NEW
9.1w (7.1 + L wide, R wide) NEW
11.1hw (7.1 + L height, R height, L wide, R wide) NEW
DTS NEO:X NEW
DTS NEO:X can upmix to any of the speaker configurations. NEW
DTS NEO:X can be applied to all decoded streams: 2/6/8ch PCM, DTS 2.0/5.1/7.1 and Dolby 2.0/5.1/7.1. NEW
Dolby Pro Logic IIx/z NEW
Dolby Pro Logic IIx works for 7.1. NEW
Dolby Pro Logic IIz can be configured for 9.1h adding the front height. NEW
Dirac Live
An additional 4 channels of Dirac will be added (16 in total). NEW

Any idea what would constitute an "approved" sale? Out of any dealer region perhaps?

No local dealer. I would need to go to Long Island to check one out.

Hi Dan, Et al.

I don't know if this will be available stateside, but just wanted to quote Neil from Genesis in regards to a lower grade, consumer Dirac kit.

Tony, if you want, feel free to come to PA and check out mine - I might be closer depending on where you are in New Jersey -- Zip here is 19454

Noob question - seems like a lot of manual tweaking and work to get Dirac "right", (unless I'm reading this thread wrong), compared to Audyssey Pro. I know they are different approaches, so not trying to compare them as apple's to apple's - but is Dirac "more complex" than some users here may have surmised or hoped?

Connected to this, is there an online manual or guide that explains how one would set up and use the RS20i with Dirac? I like to read as much detail as possible about something like this...

Finally, what have you all moved up from to the RS20i? Large debate in my head about the intrinsic value of going this high for a processor. Putting aside upgradeability, are their sonic improvements over your prior setups (either the RS20i alone or because of Dirac) that you feel are substantive?

On the point of upgradability, I note the HDMI connectors are not on a user-upgradeable board. Has there been talk of what occurs when the next rev of HDMI is adopted?

Thanks all...

"... seems like a lot of manual tweaking and work to get Dirac "right" ..."

I don't think that configuring Dirac is difficult. The default settings sound very good. Rather the issue is Dirac affords such a high level of flexibility people naturally explore nuances that they prefer to hear in their systems. Audiophiles tend to be 'tweaky' by nature.

"On the point of upgradability, I note the HDMI connectors are not on a user-upgradeable board. Has there been talk of what occurs when the next rev of HDMI is adopted?"

The HDMI board in the RS20i is field upgradable. It was designed purposefully that way.

______________
Best Regards,
Carl Huff

As a professional calibrator I see the option to tweak things as a boon for those interested in the ultimate SQ. Audyssey is pretty much locked down.