PS Audio - PWD - Perfect Wave DAC

[RKL_76]

I´ve both listened to the PWD at home (with and without pre) and tried to find out how the volume control really works.

 

It all leaves me slightly confused....as it seems some manufacturers are supporting digital as the first alternative (such as PS Audio), others are going the analogue route and calling digital volume controls bad compromises and then we have the "middle way" (such as Weiss) where You have a bit of both.

 

I felt there were pro´s and con´s to running the PWD directly to my power amp, but then again the PWD is being compared to a USD12k balanced preamp so it might not be fair. Regardless, i´m looking for a DAC/pre solution to replace the current preamp and I think there are more alternatives than information out there.

 

Also, when looking more closely at the Wolfson chip used in the PWD, it turns out the volume control is part of the OEM chip itself. Does anyone know if this is the solution PS Audio is using or have they implemented a custom digital volume control? If the digital volume control is on the chip, how does it differ from the other digital alternatives out there (many of which should only be used to get the optimal working range for Your analog preamp... according to some manufacturers i´ve asked).

 

So at the end of all this rambling; can anyone get more specific on how the PWD volume control is superior or different to other designs..?

 

While I´m trying to get my head around the whole digital volume control issue, i´ll spend some time auditioning alternatives with analog resistor networks (the new Aesthetix Pandora looks interesting, as do the more expensive Msb tech alternatives).

 

Best regards,

 

RKL

 

[barrows]

The PWD uses the volume control of the Wolfson DAC. Here is the deal: This DAC operates at 32 bits, so volume control is implemented in 32 bits. With 24 bit source material, this volume control gives 8 bits of attenuation before any resolution of 24 bit material is lost, and 16 bits of attenuation with 16 bit source files (redbook CD). Each bit of attenuation is 6 dB of attenuation, so for 24 bit files there is 6 dB * 8 bits=48 dB of attenuation available with no data loss. 48 dB of attenuation is alot, and it is likely that at levels lower than this any loss in resolution (remember these will be low level details) will be below the noise floor, because one is now listening at very low levels.

When the volume control is set to full scale (all the way up) there is no change to the data whatsoever, so if one prefers to use a preamp, there is no "problem". My understanding is that there will be quantisation distortion when using the digital volume control, but this should be shifted way up to well beyond audio frequencies, and as such should be inaudible.

The PWD operates with fixed frequency clocks with the bridge, or with the PW Transport, via I2S in both cases. With the Bridge the clocks are located in the DAC, so theoretically, and difference in jitter should actually favor the Bridge, as the cloks are closer to the DAC chip itself. Most users have found that the Bridge at least equals the performance of the PWT, I am surprised that the above poster has found this not to be the case, but there are many possibilities of setup differences, rip quality, etc, that could cause this. It is also important to remember how significant it is that the Bridge equals the performance of the PWT, as the PWT easily outperforms traditional CD transports in any tests that I am aware of.

Some people are suspicious of digital volume controls, and I totally understand, and sometimes share, their suspicions. Of course, these same suspicions should also apply to any digital signal processing (which is done by almost every DAC available, with the exception of very unusual NOS designs). As always, demo, demo, demo in your own system, preferebly over time rather than in A/B tests to really get to the bottom of what is going to work for you. Right now, I am doing a long term test of Pure Music's volume control in my system, with the preamp removed (I need only 10 dB or so of attenuation with most music), but I am going to give it a few weeks of use before making any decisions.

 

[wappinghigh]

Thnks heaps for this!

 

I wont be able to trial one at home like you, but I know I can take my power amp and speakers down to a dealer and get them to hook it up. My power amp has 25 thru 32 dB of gain and 7K5 ohms impedance. Whatever that means.

 

So where exactly does the 48 dB of attenuation drop out as you are winding back the volume slider? can you work out exactly were this changes over?

 

Is there an indicator or something. Like what you might see when using a digital camera moving from real lens zoom to digital zoom (if you get my analogy)....

 

I really look forward to your reply. I think they are onto something here with this form of volume control... as long as it fits my power amp....

 

It's going to be quite a while before everything moves to 32 bits....

 

[barrows]

The volume scale on the PWD is not calibrated in dB. But, 48 dB of attenuation is a huge amount-it is unlikely that one would ever use this much attenuation, unless the system as a whole is very poorly matched for gain and sensitivity (like, say, 98 dB sensitive horn speakers paired with an amp with 30 dB of gain and 200 watts of power). As an example, in my system, normal listening levels are achieved with 10dB-15dB of attenuation.

To test with your amp direct with the PWD, you will want to use the lower gain setting on your amp (as you noted-25 dB), the lower the gain of your amp, the less attenuation you will need to use in the PWD. 7K5 ohms is very low input impedance for an amplifier, but the output impedance and current drive of the PWD should have no trouble with this, as the output stage is not a wimpy IC opamp.

 

[wappinghigh]

Will do...

 

I can see a dB calibrated volume scale in a future firmware upgrade. Maybe with a color change as it starts to erode below pure bitstream...depending on the source...16, 24 bit....

 

 

 

[wappinghigh]

"The PWD uses the volume control of the Wolfson DAC. Here is the deal: This DAC operates at 32 bits, so volume control is implemented in 32 bits. With 24 bit source material, this volume control gives 8 bits of attenuation before any resolution of 24 bit material is lost, and 16 bits of attenuation with 16 bit source files (redbook CD). Each bit of attenuation is 6 dB of attenuation, so for 24 bit files there is 6 dB * 8 bits=48 dB of attenuation available with no data loss. 48 dB of attenuation is alot, and it is likely that at levels lower than this any loss in resolution (remember these will be low level details) will be below the noise floor, because one is now listening at very low levels."

 

Hi again Burrows.

 

You obviously know this stuff. But I've been thinking and can't get my head around this.

 

You have a 24bit track. It's in digital bits. It goes into a 32 Bit DAC. Out comes an analogue signal. So what you are saying is the volume attenuation happens as the conversion to analogue is occuring, kinda like winding back the analogue signal being produced...until all the vacant bits in the DAC aren't used up anymore.

 

So it's sort of working on the analogue side of the DAC chip, until it can't do this anymore...

 

That how this works?

 

Wap.

 

[barrows]

not a digital engineer, and I do not know exactly how the Wolfson controls the volume, this question would have to be directed to a Wolfson engineer for a complete answer.

I can say: the volume control is implemented in the digital side of the chip, not the analog side, and resolution is not lost until large amounts of attenuation are used. I do not think you should be too concerned with the details of the resolution-in my experience, how the DAC drives the amplifier is what governs the ultimate sound of using a DAC direct to an amp, and not how the volume control is implemented (unless it is really poor, not the case with the PWD).

I just spent about 4 weeks evaluating running direct to my amp with my DIY DAC, using the digital volume control in Pure Music. I ended up concluding the following:

DAC-Pass X-150.5: lower noise floor, very slight increase in resolution (maybe...) less "body" to images, less dynamic expression. After longer term listening I got used to the lack of "body" and the lower dynamics, until I switched back to using the preamp...

DAC-Ayre K-5xeMP-Pass X-150.5: slightly higher noise floor, but no noise audible from listening position, even very late at night. Very slight loss of resolution (maybe...), more "body" to images, more dynamic expression-resulting in a better connection to the music.

Conclusion: Eventhough the DAC direct seemed to (maybe...) produce slightly better detail retrieval, I connected better with the music with the preamp in the chain, as the dynamic expression of the system was clearly better. I found myself not getting as absorbed into the music when running DAC direct.

Clearly the differences that mattered in my case were all about how the DAC's output stage drove the amplifier, versus how the preamp's output stage drove the amplifier, and the implementation of the volume control was really a non-issue. I further verfied this by using the Pure Music volume control with the preamp in the chain.

My experience leads me to believe that your own testing, with your own gear, is the only way to evaluate which approach will better suit your system and listening preferences.

 

[Larryken]

there's a big thread on this device but everyone seems to be talking about its' abilities to connect to a network or your computer. No one seems to address how the device sounds..its functionality sounds awesome but what does it sound like? If I buy one, I'd mate it with a SET integrated tube amp. Somewhat familiar with the PS Audio Digital Link III sound. I really don't want to buy a DAC that screams DIGITAL.

 

[barrows]

Sounds great. I would rank it along with any of the top DACs around in the 4 figures price category. It is very dynamic and natural sounding, with excellent detail retrieval. It also allows user selected access to all of the filters in the Wolfson chip, and the option to use or disable the asynchronous upsampler, this allows for some choice in sound. Beyond that, you really have to listen to it yourself. I do not know what PS Audio's present policy is, but they used to offer direct purchase, and thirty day in home trials (you only risk shipping charges if you decide to return it). Like any DAC at this level, the differences are going to come down to system matching and listening preferences-you have to listen for yourself.

 

[Quest]

Agreed with barrows that it is based on system matching. In the US, if the price is still $3k, I guess the price will be in line with its performance. It's no leader in this aspect, imo.

 

I know this is subjective, but just imo - I feel the DAC is a little bass light which shifts the focus, and has a more airy sound though not as open as I'd like it. There is a little glare on the highs but this may have been a matching thing, but the lack of refinment in the highs is consistent with dacs up to this price range. My gf also did not feel detail level was really that great somehow, though I thought it was acceptable. Price in my country is higher so perhaps there was some higher expectation on her part.

 

[sr1329]

The 32 bit explanation makes a lot of sense. It seems the DAC chip itself outputs a certain voltage at the 32-bit level (or 24 bits + 8 bits at the bottom). As it simply "shifts the bits down" I suppose it will start to output lower voltages.

 

 

I suppose it would be good to see what the Wolfson DAC's specified S/N ratio is to see how far one would need to go before the actual signal hits the noise floor. In practical use I doubt anyone would actually hit that floor since I doubt anyone has a listening room quieter than 40dB and plays their music at 140dB. So even 24 bit resolution exceeds I'd say about 99.9% of installed systems. I guess you could have a system in an anechoic chamber to try to "use" the full S/N ratio of a 24 bit signal.

 

I had the PWD in my system before, but I'm afraid I can't really comment on the sound, since I didn't do any A-B comparisons before I returned it. I returned it since I didn't have faith in the Network Bridge control system vis a vis Squeezebox or even iTunes/remote. Also the remote doesn't really work at an angle, which also affected my practical use of the device. But from what I remember of it, it did sound pretty good. I just can't say it sounds better or worse than any other 4 figure DACs. This is just my personal take on the PWD.

 

[reverendo]

Hi there,

kind of joining rather late, but have been thinking quite a lot about the PWD+Bridge solution.

ATM I use a SB Touch with my current DAC. Since I like to make things more simple without losing quality I think that the PWD might make me sell my Touch and have kind of a one-box-solution as a source.

Can anyone make any comparisons to DACs like the Weis DAC2, Berkeley, older dCS, Esoteric SA-50 and older Emm-Labs DACs? Comparisons with the Audio Aero Prima DAC would also be welcome.

BTW, I drive my Gryphon amp directly from my Uther. Does the PWD have balance controls, since I don't have a dedicated listening room it normally comes in rather handy.

Thanks a lot in advance

best regards

André

 

[mr_bill]

I owned a PW Dac with Bridge, and I also own a Touch that I used as a transport with the PW Dac.

I found very little difference between the Bridge and the Touch as transports into the PW Dac. Slight differences, but not enough to warrant a change. I grew tired of messing with my network and UPnP, DLNA, and having to use a idevice to control my system etc, when the Touch works so well. I also hated the miniature volume display on the PW Dac.

Sold the PW Dac/Bridge and am using the Touch into a Berkeley Alpha. The Alpha is a step up from the PW Dac. I'm much happier with the Alpha. Resolution and detail have increased.

The PW Dac is a good Dac but I wouldn't trade my Alpha for it.

 

[reverendo]

@mr_bill

thanks for sharing your experience. I'd love to have the BADA, but it's almost twice the price (both used), so it should be in another league. any idea related to DACs in it's price class?

best regards

André

 

[mr_bill]

Hi Andre,

I really don't have any recommendations for you as I really like the BADA but have not tried many other new dacs other than the PW Dac and I don't want to purchase a preamp - would rather run straight to amp if possible since I only use digital source.

The new Classe CP800 is the only other dac/preamp that interests me.

 

[reverendo]

I'm also on that direct input road, since I only use digital sources as well. That's how I use my Uther ATM.

thanks for helping out. will have a look at the Classe, but I guess that it's probably in another price league.

best regards

André

 

[timequest]

Interesting. The Berkeley Alpha Dac is indeed a killer DAC, but side by side, I preferred the PWD for what, to me, is a more analog-like presentation. I found the PWD to be airier, while the BADC was slightly more resolving, but more “digital" sounding. Nothing wrong with the BADC, but I feel the PWD is certainly a better value given the price difference. Besides, the Touch is limited to 24/96…

 

[esimms86]

I second Timequest's comments. I previously owned a Berkeley Alpha and sold it, replacing it with a Perfectwave DAC. I found the Berkekely to be very detailed and revealing in its sound but less involving than the Perfectwave DAC. YMMV, of course. I also previously owned a Logitech Transporter and sold it due to its 24/96 limitation. When I compared it side-by-side with the PWD, there was no contest as to which of the DACs had the more realistic and involving sound(that being the PWD).

 

Esau

 

[reverendo]

thanks for input. I am/was about to change transport. I already have an upgraded older macbook and would sell the Touch to get an M2Tech EVO (because of the ST connection, mostly). Nice to know that the PWD is such a great DAC. I'm sure it's always a matter of taste and system synergy, but since I'll be able to sell my Touch in order to help getting the upgrade without having to buy a new interface. People are always raving about the BADA, but the price difference is rather big.

I'm an Android user. I would think/hope that PS Audio might make an app for the Android interface. Does anybody know if that's in the works or if there is any alternative for Android?

 

[esimms86]

PS Audio CEO Paul McGowan has expressed interest in developing an Android app but, as far as I know, there are no plans to follow through on that at this time.

 

Esau

 

[mr_bill]

I should note that all my listening is and was with redbook so my comments should be taken in context. On redbook the Touch/BADA is clearly better to me without all the hassles of the Bridge.

I still don't get the hype about the Bridge being a better transport - in practice it didn't exceed my Touch with redbook, only slightly different and thus I was disappointed in its claims. High Res is something I can't comment on.

 

[kana813]

The PWD is an excellent DAC, and since lots of folks like mr_bill put them on the used market, they can be had at big discounts.

 

The Bridge has gone through lots of software changes that have

an effect on SQ. IMO, it still doesn't sound as good as the PWT with redbook or hi rez.

 

I wish it had channel balance like the BADA and a larger

volume display like the BADA and Weiss DAC-202. I haven't had good luck with volume control on the iPad app.

 

[vortecjr]

has anyone tried the PWD in native mode above 24/96 via SPDIF or AES?

 

Jesus R

www.sonore.us

 

[barrows]

I cannot recall if I ever used the AES/SPDIF inputs on the PWD at all. Always used I2S and occasionally USB for testing purposes. There is no reason there should be any difficulty with 24/176.4 and 24/192 via these inputs though (in native mode).

 

Volume display: I cannot resist talking about this. In the early days of PWD planning, some people at PS Audio lobbied hard for a large volume level display which could be read from across the room, unfortunately those people were not "heard". The good news is that the entire display could be upgraded to provide (via a firmware update) an optional screen with a large volume display-if enough people vocally complained to PS Audio, they would be able to develop and offer a firmware update to allow this.

 

[vortecjr]

I was just looking for feedback on the sound.....

 

Jesus R

www.sonore.us