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At last... (Audiolab) - part I

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gotta say that's Harald's '21st Century preamp' sounds like something that might stick, if the listening impressions live up to what we're expecting. :D
also think that Harald's suggestion is a great one. hope it's not too difficult to include, even if it would be a future upgrade.
 
Synfreak said:
I would LOVE to have such a feature in the upcoming Audiolab DACs too, because it is a very conveniant and safe way to ensure bit-perfect playback.

Maybe you (or Dominik) could think about implementing it?

Thanks, and take care!

Harald
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Hi Harald,

Actually our DACs do have a feature that helps you check whether there's something fishy going on with the data you're playing. It is not a full blown bullet-proof bit accuracy test, however it will catch the most likely fault scenarios.

When playing via USB, you will see not only the sampling rate, but also actual bit depth of the data coming to our unit. The USB interface is working with 24 bit words at all times, however while playing 16 bit tracks, bits 17~24 should remain zero and thus you should see 16bit on the display. That is normally a good indicator that the data are passed without any modification. Try using DirectSound instead of WASAPI, KS or ASIO and you'll get 24bit regardless of your source files. Enable dither, use a software volume control and again you'll get 24bit on the display. In other words - play a track with known bitdepth and samplerate and you should see the same bitdepth and samplerate come up on the display of the unit. If that's not the case, something's afoot.

Of course we've developed our own bit accuracy test years ago while working on FPGA based modulator designs, however these new Audiolab products are built to a different BOM cost target which sadly precludes the use of FPGAs. Nevertheless, as I say, the real-time analysis of USB data stream should cover 99% of real-world data mongering scenarios.

Regards,
Dominik
 
As far as I can tell, there are only two parts to bit accurate playback:

i) the player software must not alter the data

ii) the operating system must not alter the data

The first is taken care of by using a player in which all forms of DSP can be switched off or disabled.

Such DSP can include obvious things like special effects, tone controls, equalisers, sample rate and bit rate conversion and perhaps less obvious things like volume control or volume levelling (replay gain matching).

Programs such as foobar2000 allow these things to be turned off.

The second is taken care of by using WASAPI or ASIO. Only your chosen music player should be using these interfaces to talk to your USB DAC. Windows should be set so that the internal soundcard of the PC is the default sound device. This way Windows noises will continue to come out of the PC while your music emerges bit perfect from you DAC.

That's my current understanding. If anyone knows better, pleae chip in :)
 
@ Dominik:

Thanks for your fast reply!
I've read about the "Bit display" in an earlier post from John.
That this is a good solution for most of the users (and for most scenarios which might occur).

A "real" bit test would be better, but if there is no room / processing power for it, ok, lets use it as is ;)


Cheers
Harald
 
Oh dear! So many questions!
I'm fascinated by the CDQ, largely because I've got too many boxes!
At the moment I'm using a Tag Mclaren AV32R bp192 (single prcessor) and a DVD32R, mostly for plain stereo / CD. Good kit, but now getting old. Will the CDQ equal or even better the Tag combo?
 
JohnW said:
Russel, dookie182

I don’t have a fully built MDAC or QDAC on Hand to measure the exact current requirements, but its PSU requirements are more complex as it requires symmetrical supply rails.

The 8 Way Mini DIN (+ Outer Shield) has the following Pinning:-

+15V Digital
Gnd (Shield)

+15V Left
Gnd
-15V Left

+15V Right
Gnd
-15V Right

CBUS (Bidirectional Communication BUS to M/QDAC MCU) for PSU status etc.

The BUS connection does not need to be used, and the power requirements for the QDAC are much higher due to its 16 extra Class A Stages in its Analogue Preamplifier section.

I will post current requirements later – once we have “completed” units.
Click to expand...


Thanks John, hope the earthquakes have stopped. I guess it depends on the price of the MDAC as to whether its worth upgrading the power supply or going for the CDQ and not using the CD section. The only issue I can see is that I do not like is the return currents of the positive and negative supplies would be sharing the same path, in this case the CDQ is always going to win on sound quality no matter how good the external supply is. On the other hand if the MDAQ is better than the DaCapo, which sound wise I am happy with, then the MDAC is the winner for me.
 
Hi Russel,

I'm not sure I understand your concerns over the current paths. The only concern would be if we had shared Ground between channels. The only AC current flowing though Ground is the current thought the load - this just changes direction depending on the sign of the output signal, so there’s absolute no advantage to having a separate Ground connection for each supply rail, what current would flow though them - just one AC current that swings back and forth (if your using a single-ended load), with true Balanced operation, its just flows between the rails! :)

The vast majority of PSU current flows between +/-rails and NOT Ground, Class A operation has its advantages - as does fully balanced outputs

It’s also worth considering that the units are heavily biased into class A operation and are Fully Balanced – as such, there’s not much in the way "AC" currents.

MDAC / QDAC are going to be sub GBP500, while the 8200DQ will be priced somewhere between 8200CD & 8200CDQ – I’m guessing around GBP799 (Pls. remember I’m not marketing / Sales).

It was my first ever Earthquake, and I was sitting on the Toilet!!! – I hope the events are not somehow related. Oddly enough, the 19th was international toilet day – What you say??? But I Kid you not…

No damage that we are aware of, apparently it was a 4.9 at the epicentre – and like 2.5 here at the factory, still it was a real sharp jolt – would hate to have been in a bigger quake.

When I walked back from my lab at around 3am last night it was an amazingly clear night – and almost full moon. Unless I’m confusing my stories, I recall reading somewhere that after earthquakes you can have very clear sky… Well it certainly was extremely clear last night, so much so that I took note!
 
JohnW said:
Hi Russel,

I'm not sure I understand your concerns over the current paths. The only concern would be if we had shared Ground between channels. The only AC current flowing though Ground is the current thought the load - this just changes direction depending on the sign of the output signal, so there’s absolute no advantage to having a separate Ground connection for each supply rail, what current would flow though them - just one AC current that swings back and forth (if your using a single-ended load), with true Balanced operation, its just flows between the rails! :)

The vast majority of PSU current flows between +/-rails and NOT Ground, Class A operation has its advantages - as does fully balanced outputs

It’s also worth considering that the units are heavily biased into class A operation and are Fully Balanced – as such, there’s not much in the way "AC" currents.

MDAC / QDAC are going to be sub GBP500, while the 8200DQ will be priced somewhere between 8200CD & 8200CDQ – I’m guessing around GBP799 (Pls. remember I’m not marketing / Sales).

It was my first ever Earthquake, and I was sitting on the Toilet!!! – I hope the events are not somehow related. Oddly enough, the 19th was international toilet day – What you say??? But I Kid you not…

No damage that we are aware of, apparently it was a 4.9 at the epicentre – and like 2.5 here at the factory, still it was a real sharp jolt – would hate to have been in a bigger quake.

When I walked back from my lab at around 3am last night it was an amazingly clear night – and almost full moon. Unless I’m confusing my stories, I recall reading somewhere that after earthquakes you can have very clear sky… Well it certainly was extremely clear last night, so much so that I took note!
Click to expand...

Thanks John,

'Doh, course. Not everything is single ended push pull AB!.

MDAC looks the tempting one, especially after Christmas when funds are a bit tight. I would just be running everything from the media centre and use the pot in a box I have now, so I would be basically paying a lot of money for a remote controlled volume control.

I have to say if I were to be in a building when an earthquake happened, I think its fair to say my first choice of location would be sitting on a toilet. it could well save embarrassment later:).

Not sure about the clear sky weather effects although I seem to remember that the underground movement can cause triboelectric effects. If you get any unexplained increases in ESD failures then that may be true.

Cheers

Russel
 
JohnW said:
Hi Loris,

Getting closer to Christmas - we should be back in Czech around 21st Dec - time to start getting you unit ready I guess... :)
Click to expand...

I'm happy to hear this. When you put the hands on that board, remember I have another sick dacapo here. (I measured the clock of the dacapo with a locked signal and it's 16.730. Should I check some other point?)
Thanx a lot John.
Loris
 
Hi John, have you experimented with any active speakers recently? only asking as the MDAC (Or DQ / CDQ / QDAC) would be a very neat system running into actives with just a digital source, I've been looking at some mini/midi systems recently but this combo could be more cost effective.
 
haven't gone through all the 38 pages - are there any reliable listening tests or experiences to share? doesn't have to be from the reviewers, private are just fine. thanks
 
Dan.Scott1234 said:
Hi John, have you experimented with any active speakers recently? only asking as the MDAC (Or DQ / CDQ / QDAC) would be a very neat system running into actives with just a digital source, I've been looking at some mini/midi systems recently but this combo could be more cost effective.
Click to expand...

Hi Dan,

I would recommend buying the MDAC as you don't need analogue inputs, then spend the rest of your budget on the best pair of active speakers you afford. I cannot recall the brand but there's a pair of speakers using Ribbon tweeters & power amps built by TIm P from EAR (sorry no chance for me to spell Tim's surname correctly). I've not heard them, but the combination of active speakers with Ribbon tweeters and Tim designing the power amps - I'd bet that's going to be hard to beat!!!

What you really want to find is a version of active speakers with no input volume control - leaving level control duties to the MDAC - this would reduce the signal degradation... Worth asking the above company...
 
I'm sorry to ask this again, but I think a lot of people who in practical terms only need the functionality of the cd player, will want to know -

The changes that were made into the CDQ design that were too late to be incorporated into the CD before it's production run - are they to be applied at a later date to the 8200CD ?
 
Loris,

Are you sure your using the counter correctly, check the trigger levels, and that the counters inputs are terminated correctly, sounds more like a measurement error then a real issue...
 
Hi Cloth Ears,

No plans ATM, as the units have already been reviewed. All 4 reviews have been extremely positive!
 
The speaker you refer to John is the Unity-Audio 'Rock' a little composite cabinet number by the guys who do those helmholtz cavity tuning devices. Both of which sounded great at the Hifi show the other month.
 
Hi Russel,

Once the MDAC's shipped I'd be happy to help with any PSU upgrade advice, MDAC's will make a great platform to work with... If the sound quality of the CD/DQ & CDQ are anything to go by... :)
 
sq225917 said:
The speaker you refer to John is the Unity-Audio 'Rock' a little composite cabinet number by the guys who do those helmholtz cavity tuning devices. Both of which sounded great at the Hifi show the other month.
Click to expand...

Hi SQ,

Yes, thanks

Unity-Audio Rock!!! That's the guys...
 
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