One more thought in no way am I saying I know how it should sound as for accuracy of timbre or vocals . I simply completely lack this . But I do know what I feel it should sound like and hear a change .
Al d
My research on digital vs analog domain volume control has been expanded. Of interest to me (and maybe others on the forum) is that designers of DACs implementing really good analog volume control favour R2R (multibit) ladder DACs. The examples I refer to include MSB, Lampizator and AMR.
http://positive-feedback.com/Issue65/dac.htm
http://www.6moons.com/audioreviews/wyred4/sidebar.html
http://www.lampizator.eu/lampizator/TDA1541%20corner/TDA1541.html
http://www.youtube.com/watch?v=1CkyrDIGzOE
From what I have gleaned (although this subject is very difficult to generalise on), real analog domain S/N ratio and dynamic range are influenced by noise shaping curves employed by ds DAC chips. Thorsten Loesch has some interesting views on the “real” resolution of ds DAC chips. And if we believe his views, digital attenuation introduces audible differences due to greater reliance on the output noise shaping employed by the DAC chip. So audible artifacts are present even before surplus bits are stripped by the digital volume control.
The opposing view, advocating for multibit R2R DACs, suggests that there is greater “real” dynamic headroom from this approach. This seems to be why several high end companies (including the ones I stated above) then see fit to augment their approach with an analog volume control. It seems each designer arrived at this conclusion separately and independently.
I seen this video , I thought it was posted here but maybe I’m wrong. I watched it twice very interesting, and easy to follow at least with his illustrations anyway. It was intriguing just how far off some of the simple volume commands were. Although he was an advocate for using the sabre chip and discussed per implementation methods. As for the other dacs that is argued on other forums as well. There are those saying the msb is best , while others claim by adding a preamp it’s better. I am of the camp as what Paul said a while back as less is more, unless you need or want the effect that the preamp gives you. Such as tubes or gain matching. I did play with Paul’s dac with the msb anolog input and at 56/75/85/100 . I could not hear a change drasticly enough to be sure. But there was a dac there that as clearly terrible at this , as when connected to the msb input it changed drasticly. I also could easily here the difference when useing the Logitech front ends volume control. Terrible as well , but fine with volume disabled as the dac was too.
What ever Paul’s dac has inside is pretty good. Again I am not a golden ear either. Someone here or on another site claimed there preamp anthnix or something like . Blew away the msb anolog I asked them to describe what they heard . But there answer was not explanatory to changes , just saying it was much better. They also did not describ the conditions of the setup either.
Al. D
The video I posted is of Martin’s talk just prior to the one he did on volume control (posted earlier in this thread).
For sure many other factors are at play here. I also agree the PWD implementation of volume attenuation is very good. But my OCD audiophilia drives me to better my understanding (and my system) where possible.
MSB design there own ladder DACs. Thorsten’s AMR products use the multibit TDA1541. Lampizator DACs use an unknown multibit chip. They all use high end analog volume control. Is this just a coincidence?
No I do not think so. And there is a company called trinity . They make a dac and other comp as well.
Very hi end. They too are anolog. But a point to consider in this , if you charge an extremely high price for your wares . There needs to be an absolute philosophy with it. So lampi there dac is secret , MSB makes there own. The trinity dac is pcm1704 uk chip the one that is not being made main stream anymore. Only TI
Makes it now. They claim to test a thousand chips at a time and only select the ones with extremely good spec,s. And the sell the rest. It’s all a ploy in a way, why buy and listen they need to show us why they are much better than every one esle. Incidentally I listened to the lampi too. Level 4 , 4 edition. It’s a nice dac but on the warm side of neutral . Even more warm than Paul’s dac. As we both agree Paul’s volume control is very good, and the video I watched admitted to flaws but did show very good impimentation does yield good control.
I have someone coming to my office this Saturday to listen to my system , they have a lampi. Let me know if there is anything I can do for you .
Al d
Thanks Al. I will look into Trinity to further my research.
I understand the Lampizator is warm. The option Jensen coupling caps apparently improve this tone to more neutral. I am interested in the optional volume control and how good it is, or rather how well it is implemented. Perhaps PM me.
Ok.
Trinity seems just a smidge expensive at $60k AU…
Yes sick money. But it is the hot and heavy DAC for the elite right now. But the point is the implinmintaion
Is somewhat unique . And so is the volume control, that’s the point in this. I read a thread on another forum how a guy bought this with the transport . His conclusion was it was the best he ever heard, he owned
The MSB stack. Diamond all in. And if you look at the inside and outside it looks like a DIY kit right.
So some of this is really conjecture. When I did the DAC shoutout it’s was with Nola baby grand speakers
About 50 k with out amps. The speakers had a magical sound to them and a great resolution . So any small changes were very apparent. I could not say with certainty that bypassing Paul’s volume mattered. Of course I thought I heard changes but could not replicate constantly and if I closed my eyes not be sure. Now poor volume is a funny thing to peg down. It vials the music a little , it takes away some dynamics and lastly it affects the tonal balance . So it is complex. Please I was not sugessting to actually buy one. It’s absurd to me. I recently went to NYC in a showroom that had the Alexa,s Wilson audio top speaker. About 180k.
On some really great looking amps by the krell guy d’augistino .
Anyway I have heard those speakers a few times and to me I just do not like them. The Nola is much cheaper and just sounds euphoric to my ears. Some of this is just us alone in our views. But like you say
It is higher education in this hobby.
Al
Getting back to emalists’ comment: After having no preamp in my system for a while, then getting the preamp back (with a slightly different volume control revision) I can really say that it is quite beneficial to have the PWD at full volume, at least in my system.
It is my instinct (no proof) that the least digital manipulation would occur at full volume on the PWD. Therefore, when hooked up to a good preamp, running the PWD full volume into said preamp should be preferred. Can someone from PS Audio give an opinion on this?
It is true the least digital manipulation occurs at full volume.
We need to remember however, that bit shifting to empty bits to lower volume does not change the digital data. Instead, it merely tells the DAC to lower its output voltages.
Thus it is unlikely one of us will hear a difference running the PWD at 100 and at 85 into a preamp - as long as the volume of the preamp is properly adjusted to make up the lost PWD gain.
Of course, it is also possible a given preamp just loves the output of the PWD at 100 and does, in fact, sound better.
Does anyone have any thoughts on the emerging group of designers (MSB, AMR, etc) who choose to use ladder (multibit) DACs and analog volume control. I think only single bit (ds) DACs allow digital volume control.
Many of these ladder (multibit) DACs get very favourable reviews, some might say in spite of analogue volume control that is often part of the DAC/preamp 1 box solution. And yet the designers set out knowing they need to find the best solution… ds DAC with digital volume control or ladder DAC with analog volume control. I seems there are a few out there who look at this scenario and still favour the latter. I wonder why?
I am not sure about a growing number of ladder DACS, I am only familiar with the MSB one. I am not familiar with the other you mention. I don’t think there’s anything in common I can see as a trend other than 99% of all DACS are Sigma Delta based (like ours) and the volume controls are built into the DACs. I can play our DAC at 85 or 100 and it doesn’t sound identical, but close. However, I don’t think it is related to the DAC itself in this experiment. As Elk suggested it is more than likely to do with the preamp.
All preamps sound different at different gain settings. That’s just the nature of an analog volume control and one of the reasons I am not a big fan of an analog volume control. They are extremely imperfect devices.
I am a big fan of using the digital volume control if it is done correctly as ours is. If the system sounds better with a preamp in (as mine does in one sound room, but not the other) it is most likely because of the euphonic additions wrought by the preamp. I recognize that when I added my preamp I did so because the system became a bit more musical - but I also recognized it was because the preamp was adding something pleasant. That’s ok, just recognize it for what it is.
I wouldn’t blame the DAC or its volume control.
Thanks Paul, as always.
I don’t have separates (yet) as I’m going direct into the (excellent) AR VSi60. At some point I will upgrade to a Ref75 and will be able to experiment with direct into the amp. Should be an interesting experiment. It’s a bit of an impractical setup, though, as I still have lots and lots of LP’s and a preamp serves an important input switching function.
I am 100 % behind Paul. It’s a case by case basis. There is just to many small variables to attribute changes we may here in our systems .just consider some of them , interconnections , over all synergy ,
And Resolution of your speakers . Any and all of these can contribute or hide what changes may be affected with the volume control. As I stated in my own little test , there were some small changes . But they were not
Obvious enough to comment on and as such not consistent . My test was on the nola baby grand a great speaker, but I’m betting Paul’s IRS is beyond that . So I am not saying do not try as we all must be satisfied
With our systems, even if only part of the time.
Al
stereophilus said: I think only single bit (ds) DACs allow digital volume control.
Actually, volume control cannot be applied to a single-bit data stream. In fact, a single-bit data stream cannot be manipulated in any fashion. This is why DSD cannot be edited.
Volume changes are made on a multi-bit level. with the more bits the better. The data stream is then decimated prior to DAC conversion by a single-bit DAC (or, more typically, by a four to six bit DAC).
MSB's ladder DAC is multi-bit and contains a high precision resistor for representation of each bit. The precision required to physically construct a ultra-high quality 24 or more bit ladder DAC is mind-boggling. This in part explains the high cost of MSB's DACs. Also expensive is their analog volume control which is an analog stepped attenuator.
stereophilus said: I think only single bit (ds) DACs allow digital volume control.
Actually, volume control cannot be applied to a single-bit data stream. In fact, a single-bit data stream cannot be manipulated in any fashion. This is why DSD cannot be edited.
Volume changes are made on a multi-bit level. with the more bits the better. The data stream is then decimated prior to DAC conversion by a single-bit DAC (or, more typically, by a four to six bit DAC).
MSB's ladder DAC is multi-bit and contains a high precision resistor for representation of each bit. The precision required to physically construct a ultra-high quality 24 or more bit ladder DAC is mind-boggling. This in part explains the high cost of MSB's DACs. Also expensive is their analog volume control which is an analog stepped attenuator.
You got to always consider the theoretical superiority of one architecture over the other, and what is actually audible. I have an MSB DAC and could not really tell a difference between using their analogue volume control, and using upstream digital attenuation (in this case Trinnov). Trinnov is another well implemented digital VC - they same that is used in the $40K ADA reference surround sound processor.
This makes sense to me. Both forms of attenuation can work superbly if well-implemented. These are two excellent systems.
Digital falls down at high levels of attenuation as bits drop off and as the thermal noise floor comes into play. Analog is unquestionably better in this context.
A quality stepped attenuator sounds good at all settings in my experience. But they are pricey.
About 3 k for some .
Al
Perhaps a combination could be the best solution. Digital attenuation for the first 24dB (4 bits), then insert a 24dB pad in the output and return the digital stream to full scale. With only one precision matched pad you could get 48dB of attenuation with essentially no loss in the digital stream as 20 bits still represents 120dB dynamic range that is a challenge for any analog path to match. One precision matched pad should not be terribly expensive. A second 24dB pad would net us 72dB attenuation with essentially no loss in audio quality.
Hey, Paul: I’m still trying to get you to see the Right way! 
Perhaps this could be implemented in the PWD Mk. III.
J.P.