Long awaited Smyth SVS Realiser NOW AVAILABLE FOR PURCHASE - Page 101

Quote:

Originally Posted by Kiritz 

Yes, the HDMI input to the realizer bypasses the D/A converter in the Realiser.  But obviously, the phones are analog, so somewhere the signal has to be converted back to analog.  So I am in fact using the D/A conversion from the Realiser for this purpose.  I have no idea if I would hear the difference using an external DAC from the built in DAC of the Realiser.  In any case, I am doing this whole thing without an amp or preamp and I am not sure if I could use an external DAC between the Realiser and the phone amp directly without amplification.

I think there may be some confusion and ambiguity here, just in terminology, trying to describe the various pieces and their interconnections.  Better to be a bit more wordy to avoid that ambiguity.

The HDMI input to the Realiser bypasses the A-to-D conversion which would otherwise occur in the Realiser for each discrete channel, if you were using the 8-channel analog inputs.  The HDMI input feeds the same already-digital discrete 8-channel input (i.e. LPCM) directly, so it can be fed immediately to the SVS processing in already-digital form.

On the other end of the Realiser, there is now a D-to-A conversion required to feed your OUTPUT DELIVERY SYSTEM to get the 2-channel sound to your amp/headphones and your ears.  This involves either the built-in D-to-A converter (DAC) in the Realiser and the Realiser's analog headphone output going to your amp/headphones, or an external DAC (fed by optical cable from Realiser to DAC) feeding your amp/headphones.

You say "I am doing this whole thing without an amp or preamp" but I don't know if you're thinking about the INPUT side or the OUTPUT side.  I would think you MUST be using at least the standard Stax amp/headphones that came with the Realiser, or equivalent or better... on the OUTPUT side.  So perhaps your "without an amp or preamp" comment is meant to describe your setup on the INPUT side.

In other words, if you're feeding the audio output of your Oppo directly to the HDMI input of the Realiser, then now I understand what you're saying.  Absolutely there is no amp/preamp being used ON THE INPUT SIDE.

Some people (such as myself, who don't have an HDMI-enabled Realiser) connect their source device(s) to an AVR via HDMI (with decoding occurring either in the source device and delivered as LPCM to the AVR via HDMI, or they deliver the still-encoded signal via HDMI and let the AVR do the decoding).  Then the 8-channel analog preamp outputs of the AVR connect to the 8-channel analog inputs of the Realiser.

Alternatively, if the AVR has an available second HDMI output, then the source Oppo device could do the decoding and deliver multi-channel LPCM to the AVR via HDMI, and the AVR would then "pass-through" that same multi-channel LPCM input signal to its own second HDMI output which then goes to the HDMI input of the Realiser.  The first HDMI output of the AVR would go on to the HDTV, carrying the digital video signal fed from the Oppo source device.

This approach uses the source Oppo to do the digital audio decoding into LPCM, and passes the result THROUGH the AVR and on to the Realiser with no processing whatsoever occurring in the AVR.  There is still conceptually no "amp/preamp" involved, as the AVR is just a "digital relay" in the connection diagram.  The true decoding to LPCM still takes place in the source Oppo and the Realiser sees exactly that identical LPCM digital signal via its HDMI input, exactly as in your own current situation where there is no middle AVR involved at all but the Oppo is connected directly to the Realiser via HDMI.

There has yet to be mentioned any AVR available that can do what the source device(s) can do, namely accept encoded audio via HDMI and decode it to LPCM form and put it out over HDMI.  The AVR I have (Yamaha RX-V863) can accept encoded audio via HDMI and decode it, but it can only deliver the decoded output over its 8-channel analog preamp outputs.  It cannot deliver the deocded output digitally as LPCM over its one HDMI output.

Also, the newer model AVR (RX-V871) which does now have two HDMI outputs (to go with its eight HDMI inputs, instead of the three HDMI iputs my V863 has) still cannot deliver LPCM over HDMI output.  This still seems to be only a feature of the source device(s)... unless you have to go WAY UP in AVR price to get "output LPCM via HDMI" as an option.

In any case, there is no problem whatsoever in using the decoding of the source device, delivery via LPCM over HDMI out of the source device into any AVR, and "pass-through" of that identical LPCM stream to an available second HDMI output which feeds the Realiser.

Or, if only one HDMI output is available on the AVR, that single HDMI output (carrying both source-decoded LPCM audio as well as digital video) can still be delivered to the Realiser's HDMI input, and then the HDMI output of the realiser be used to "relay" on the digital video signal to the attached HDTV. There have been no reports on this thread yet that describe such a setup, but it's theoretically possible as that was the reasoning behind providing the HDMI pass-through output on the Realiser.

Quote:

Originally Posted by Kiritz 

In any case, I am doing this whole thing without an amp or preamp and I am not sure if I could use an external DAC between the Realiser and the phone amp directly without amplification.   I don't know the implications of using the optical interconnections.

Just to clarify...

The built-in OUTPUT DELIVERY SYSTEM from the Realiser (to deliver its SVS-processed digital final result) starts wth the internal built-in D-to-A (DAC) conversion in the Realiser, providing 2-channel analog output to its own built-in headphone outputs.  This analog output then goes (via RCA) to the analog inputs of your amp/headphones.

The alternative being discussed is to tap that still-digital SVS-processed 2-channel final result and deliver it to the digital optical output of the Realiser. This still-digital 2-channel signal is then delivered optically to an external DAC where the D-to-A conversion now occurs.  Typically these high-end external DAC devices probably (or certainly) do a better job of producing 2-channel analog results than would the built-in DAC in the Realiser.  Certainly the general (or optional) availability of a further built-in analog amplifier in the external DAC adds yet another place for "gain", to better match the amp/headphone requirements.

And finally, external DAC devices almost always provide both XLR outputs as well as RCA outputs, to be able to feed the amp/headphone using the generally accepted superior XLR approach... with both of these potentially "gained" through the volume control of the DAC, if present.

That's what the optical output of the Realiser is for... to feed the still-digital SVS-processed digital output to an external OUTPUT DELIVERY SYSTEM, starting with an external DAC, to get the analog 2-channel headphone output to your ears.

Well the Realiser's built-in DAC isn't really a "weak link".  It's fine quality.  It's just that based on my own results, having invested in a high-quality external DAC, it does appear that the D-to-A output delivery system can definitely be improved through an external DAC, and XLR connections instead of RCA, and a better headphone amp, and better headphones.

In other words if you improve any or all of the pieces in that output delivery system you WILL experience better sound from everything, be it 2-channel ordinary CD audio or multi-channel SVS-processed sound.  I'd have to say it's not just better sound quality for multi-channel, but it also seems to be a more thrilling and realistic 3D-illusion of the [AIX] PRIR listening environment.

I don't know what you're thinking of when you ask about "signal limitations of the optical output".  There are none.  It's the very internal SVS-processed digital results, delivered in still-digital form to the optical cable and hence on to the external DAC. What kind of "limitation" are you thinking of?  This isn't an alternative to HDMI for the INPUT delivery. This is simply the 2-channel stereo SVS-processed result, to be sent to your headphones and your ears.

I don't think you'll be sorry if you add any or all of these upgrades.  Hey... it's just money, and a one-time permanent investment.  And it's true that with an upgraded superior amp/headphone, you would hear the improvements provided by the external DAC and XLR connections more than if you continue to use the entry-level Stax system that came with the Realiser.  That's really just my intuition, but it makes good sense.  Better amp/headphones make ANYTHING sound better.

Quote:

Originally Posted by Kiritz 

One question:  didn't you have to go back to AIX with a new set of phones?  I assumed that the calibrations were specific to the phones, so if they were done using the STAX that came with the unit and I use different phones I would need to start over.  Correct or no? 

No.

There are two separate measurements PRIR and HPEQ.

The PRIR represents the listening environment, and only involves the room, microphones, and your ears.  It has nothing to do with what DAC/amp/headphones will be your OUTPUT DELIVERY SYSTEM for whatever the Realiser does with whatever will be your eventual source content.  It is simply a "sonic photograph" taken by the microphones, of how the overall sound of that room sounded to your real ears.

THE HPEQ has nothing to do with the room or listening environment measured by any particular PRIR.  It only represents the sonic characteristics of your DAC/amp/headphone DELIVERY SYSTEM, and how that delivery system sounds to your ears.  That's why the HPEQ is created by putting microphones in your ears, and then your headphones over your ears, so that the microphones can pick up what the headphones are delivering.  This HPEQ measurement can be made in your bathroom, or your kitchen, or your bedroom, or anywhere that the Realiser can feed the microphones in your ears.  Doesn't matter, because the headphones are over your ears with the microphones inserted.  It has zero to do with what any PRIR represents.  It only characterizes how your OUTPUT DELIVERY SYSTEM sounds to your ears.

If there was an HPEQ created when you visited AIX, it was simply done for the amp/headphones that Lorr brought with him... just so you could do the final A/B-comparison of the PRIR measurement vs. the actual real room/speakers.  If it was your actual amp/headphones for the HPEQ measurement performed at AIX, then this HPEQ is actually a true "keeper" for you.  But otherwise it's really just for use at AIX, to do the final A/B-comparison.  You would be expected to do your own true HPEQ measurment with your own true DAC/amp/headphones back at your home.

So, the only thing affected by a change to any component in your OUTPUT DELIVERY SYSTEM is the HPEQ.  It is 100% independent of any PRIR you're going to pair that HPEQ with to produce a "listening preset".  Go with an external DAC? Change your headphones and/or amp?  You need to recreate a new HPEQ, because your OUTPUT DELIVERY SYSTEM has changed.  But the AIX PRIR "sonic photograph" (aka "SVS filter for that room") is completely irrelevant and unaffected.

I was apparently stunningly lucky when I did my own, first, HPEQ in December when my SRM-007tII showed up.  I honestly had planned to make this just an experiment, and was going to drive up to Smyth to have Lorr put the microphones in my ears.  I still want to.  But astonishingly the results of whatever I did have apparently been perfectly fine (actually, terrific), because it really does sound fantastic.  Nothing strange or odd or misplaced in the sound cues.  Sounds perfect.

Now I did break in the new DAC, new XLR cables, and new SRM-007, for about 150 hours before even attempting it.  I didn't have it all on solid for the whole time (because someone mentioned that it was not a good idea to keep the Audio-GD NFB9 on straight for that long) so there were several breaks.  But all in all, the new stuff got about 150 hours of use before I did my own HPEQ.

As far as the output voltage of these Stax electrostatic amps, I believe they put out 580v.  That's just the design to feed their "pro" electrostatic headphones.  The SRM-727 is essentially the same as the SRM-007, except the SRM-007 has two RCA inputs instead of just one (and INPUT1 has a parallel pass-through line-out, for a tape-loop) along with the XLR input.  Otherwise I believe the audio specs on the two units are the same.

Quote:

Originally Posted by n3rdling 

SRM-727 and SRM-007t amps are not the same at all...not sure where you got that idea.  However, the SRM-007t and the old SRM-T1 ARE essentially the same.

My mistake, I guess.  I read the specs on the two of them rather casually I suppose, and didn't pick up the differences.  And there are some differences, and I simply noticed the one-less RCA input on the 727.

The tubes in both are the same, and the rest of the specs are very similar, so I wonder if there's an observable sound difference in the two?  I've never listened to the 727.