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At last... (Audiolab) - part II

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John, do you agree the theoretical ideal set-up will be with a power amp with adjustable gain or low gain, so your normal/max listening level is with CDQ in digital pre with output at or closest possible to 0?

some power amps (emotiva is an example) have very high gain +33db i believe and you will be playing your CDQ with volume at max -25 or -30 depending on your speakers/room etc of course.

In my present set up with Rotel class D power amp (i think gain is 27db) and 86db speakers, -10 on the volume is loud listening level on most cd's








JohnW said:
C&H, Dane, Technobear, Wilky,

When used with external Pre-amplifier set to Digital mode – and 0dB.

John
Click to expand...
 
dane said:
John, do you agree the theoretical ideal set-up will be with a power amp with adjustable gain or low gain, so your normal/max listening level is with CDQ in digital pre with output at or closest possible to 0?
Click to expand...

Ideally you would determine the maximum listening level you will ever use in your system, write down the level on CDQ's display and bring the poweramp's gain down accordingly. Apart from reducing closed loop gain of the amp - which has stability implications - you could put a fixed resistor divider at the input (could be inside the RCA/XLR plug on amp's end) that would scale the signal down by the right amount of dBs.
 
Does anyone have problem playing 24/96 material using foobar/wasapi on win7? I occasionally get some clicks/pops and on CDQ screen instead of the frequency input I get ERROR. When using ASIO4ALL the problem goes away... Any ideas?
 
JohnW said:
I think the noise your hearing via the AMP / PC is a system grounding issue – as the noise is not present on the CDQ with Headphones. As I say these ARE internally the same outputs in the CDQ that you use with the Line Outputs or Headphones – but how and why you hear when replaying via the amplifier I cannot answer ATM... But I’m sure the USB isolator will solve your systems’ issues.
Click to expand...

I think you are right. If the noise cannot be heard on sensitive headphones then it is not present in the signal output of the CDQ. It must be passing via the ground from the PC, through the CDQ to the amplifier so I need some kind of ground isolation.

It isn't a ground loop as the laptop was using it's battery.

It's worth restating that I have to put the volume control of the amplifier beyond the point at which it would be clipping in order to hear the noise when using the laptop so it isn't an issue in practice.

Seems my Tranquil PC T7 Atom, whilst being audibly silent, is electrically noisy.

So there is nothing wrong with the CDQ but when you design your next DAC, you might like to build in galvanic isolation on the USB input.


The build quality of the CDQ has got me wishing the various 8200 power amps were good enough to replace the Croft :eek:

I might have a word with Audio-T and see if I can get the monoblocks on loan :D

But first, I'm going to order a USB isolator...
 
gr0001 said:
Does anyone have problem playing 24/96 material using foobar/wasapi on win7? I occasionally get some clicks/pops and on CDQ screen instead of the frequency input I get ERROR. When using ASIO4ALL the problem goes away... Any ideas?
Click to expand...

I came across one VAIO laptop running Vista that was giving USB transfer errors - it literally chopped off packets once in a while. This resulted in a horrible static noise as the incomplete samples messed up data alignment in a buffer. Due to this experience I've implemented continuous data integrity checking which throws an error whenever such a thing happens. You can see the "Error" appear in place of the bit depth for a short while and the streaming is restarted.

I think you might be experiencing the same problem. I am surprised ASIO4All makes a difference though. Try Kernel Streaming in place of WASAPI and perhaps DirectSound just out of interest. Try playing with priority settings of foobar and ASIO. Try other USB port.
 
KS streaming is doing the same thing. I also tried other usb ports but still the same.
Later i'll try another computer and see what happens...
 
This is a great thread, thanks to the input of John W.

I'm very curious about the DQ. It sounds like it'll be a great bit of kit!
 
John, Hi again. Finally took delivery of a CDQ yesterday. I'll do the good news first.

It's a fantastic music player. So far I've only listened extensively to CDs, and I'm doing so with a set up that's not on the same quality level as the CDQ - a Marantz PM-78 in Class A mode driving an old set of Quad 11Ls with biwire Silver Anniversary. I'm using unbalanced Acrotec 6 nines phono leads between the CDQ and the amp. The improvement on my previous CD player, a much loved Marantz CD-17D with a Net Audio clock upgrade, is huge.

The sound is open, fluid, natural; all the adjectives that others are mentioning. The soundstage is huge and the definition on instruments really precise. I'm hearing things in CDs that have been favourites for decades and love the overall effect. I find the Optimal Transient XD filter works well with quieter acoustic music, and Optimal Transient filter marries well with rock and harder electronic pieces. Compared to the CD8200 I demoed in-store before ordering the CDQ, the work you've done on the bass playback is clear.
One caveat: while everything I've played sounds better, the difference between well recorded and mastered discs and poorer ones becomes blatantly obvious with the CDQ.

Externally, the unit is well built (a flimsy CD drawer excepted!). The remote is intuitive to use with a pleasant feel to it. It runs warm, but nothing excessive. Great stuff.

Now the bad news. I left the unit on overnight with a CD on repeat to run in then woke up very early this morning and set my computer up with ASIO4ALL and Foobar and had a quick play with the USB hook up. Following the impressively comprehensive instruction manual had everything running smoothly though it was too early to turn the volume up and test the sound quality. Unhooked the USB cable from my computer, returned the CD to repeat mode, turned off the amp and left the player to burn in some more. Bit annoyed when I came back to mid-morning to find the player had turned itself off. Properly disappointed when I discovered that the CDQ had blown one internal 5amp fuse and was about to blow another when I replaced it with the back up. The second one seemed to go as soon as powered on as there was no response from the unit at all. The fuse on the power cord (5A rather than the 3A described in the user manual) looks OK.

This is all sounding similar to Miki Vee's blown fuse problem. For reference, the USB cable (a QED Qunex) was left plugged into the back of the CDQ while the CD was in repeat - didn't want to pull the CDQ away from the wall to disconnect the USB when I was planning to use it again today. I was listening in digital pre-amp mode and didn't have any problem with low-level hiss. The unit's serial number is 82CDQB0243.

Sorry to be the bearer of more problematic news. Still think it's a fabulous piece of hifi, just want to get this issue solved as quickly as possible.
All the best, Duncan
 
Interested in trying out a CDQ soon to drive my pair of poweramps.. But my biggest concern is that there is only one pair of photo outputs.
What would be the easiest way of doubling the outputs? (I need to run phonos to both poweramps). Could I use some sort of adapter on the balanced outputs along with the phono's?

Thanks,
Sam
 
Hi Duncan,

I guess your referring to the Fuse on the rear panel mains AC input IEC input socket?

Ok this is the second unit to fail now with what appears from a distance to be the very same issue. My first suspect would be a batch of faulty transformers.

So until we are able to find out the root cause of these two failures, we are putting a hold on shipping CDQ's from the UK.

If you could Pls. return to the CDQ to your dealer ASAP - so the UK service centre can take a look, I will also arrange to come over to the UK once we have received the two failed units.

As soon as we understand the issue, I will get a replacement unit to you.

I'm sorry for everyone who's been patiently waiting for the CDQ, but Pls. understand that we need to understand the issue of these two failures - one is unlucky, two is more then worrying.

It's something related to this production batch - as we have many "unofficial" CDQ's in the field which are being used daily for many months now...

I'll keep everyone updated with the results.

Miki Vee,

I spoke with AudioLab UK, and they are preparing a replacement CDQ for you (with the hope it can be shipped to Bartlett’s for Saturday collection) - we would like to get your first unit back ASAP to understand the issue (and if it’s the same as Duncan’s) - We will leave your second unit burning-in and fingers crossed ATM.

To everyone, I'm very sorry we will solve this ASAP (and trust me, I'm as keen as anyone to understand what’s going on)!!
 
Hi John,

Regarding the 'hiss':

Using unbalanced RCA, in digital preamp mode, in a quiet room, sitting about 3m from speakers I can hear hiss from both speakers. Upon closer inspection it appears to be coming from the treble and mid range units but I can't hear anything from the bass driver. The hiss is at a constant level regardless of volume.

Switching to analogue preamp mode and/or using balanced cables reduces the level of hiss to a point where I have to go right up to the speakers and rest my head near the treble unit to hear it.

I'm surprised not all cdq owners have this issue, does this mean my unit could be faulty?
 
Hi John,

Yes, both rear panel fuses have gone. The second fuse as soon as it was put in place.

Have already contacted my dealer who is trying to an arrange a replacement unit through the Audiolab rep. Would be extremely grateful if you could help nudge Audiolab in that direction so that I'm not facing another long wait to have the CDQ in my living room - was thinking 'great, got it in time for my birthday', and then the fuses blow!

As for returning the unit, I could arrange to have it sent directly back to Audiolab UK if that helps. Either way there is a CD in the unit that needs to be fished out...
 
Arcam P1 monos and XTZ 99.36.

I had the same issue with a different pair of speakers/amp combo.

Do you still think its my kit?
 
MI55ION said:
Arcam P1 monos and XTZ 99.36.

I had the same issue with a different pair of speakers/amp combo.

Do you still think its my kit?
Click to expand...

Maybe. The P1 gives out 175 Watts into 8 ohms for just 900mV input. The speakers are to the higher end of the 'normal' range at 90dB.

I think we are seeing a bugbear of digital pre-amps here.

In an analogue pre-amp the noise (hiss) is reduced along with the signal so S/N ratio remains high.

In a digital pre-amp the noise is not reduced with the signal. It's constant.

Either the digital pre-amp has to be extremely quiet or a sensitive system will let you hear it.

The answer here is to use some form of analogue attenuation between the CDQ and the amps. I would use high quality metal film resistors but some people prefer carbon film. I'm sure John can advise on the best values to use for this application.

As the CDQ puts out 2V at full tilt and the P1 needs 900mV, the resistors can halve the signal voltage at least.
 
My CDQ was waiting for me when I arrived home this evening and I just swapped it for my 8000C and am listening to the CD. Quick flick through the filters and certainly with Eric Clapton unplugged the Optimal Transient reproduces the feeling of space.

The effects of the filters are easily heard and will need more experimentation.

I am a bit reluctant to connect to the computer and am just enjoying the music. My thought was to flick through differnt types of music quickly but I just don't want to take Clapton off - and it's not even a cd I listen to much. Can't wait till it's run in.

On the blowing fuses issue I am a bit concerned. USB3 can provide more power to connected devices so should we make sure that we connect to a USB2 port or will it not make any difference?

On the digital hiss issue with the volume at +3dB I have to be right up against the speaker to hear any faint hiss at all.

My inclination is to listen to my FLAC files via optical for a few days to enjoy my new toy rather than take a chance on blowing some fuses and having to sit and look at it sitting quietly.

Cheers

Norrie
 
Just been listening to Kraftwerks Tour De France 2009 remaster.
Tell you what, hiss or no hiss, that sounded f**king incredible.
 
Hi All,

Ok, with the rush of bad news I panicked a little based upon incorrect information – I was originally told the UK had only shipped 10Pcs of CDQ – and with the 2 blown fuse units and with Tim’s “Hiss” issue it was all looking VERY grim!!

But noon today I found out the UK has in fact shipped over 250Pcs this past week or so – so now the numbers don’t appear so bad!! (but I’m very sorry for those whose units have failed).

IAG UK is all out of Black units and only has a very few Silver units on hand.

Duncan,

if Audiolab does not have a replacement Black unit (and your unit is black) you have 3 options:-

1. Take a silver unit (OK not a viable option if your system is Black!)

2. Wait for a NEW replacement unit arriving in next batch in February (not good for your Birthday I’m guessing – and why should you have to wait any longer).

3. In light of these issues, I will be in the UK early part of next week, I will personally repair your unit and deliver it to you in person, and (in fact I will swap out the internals from a brand-new Silver unit).

MI55ION,

As Technobear has already answered, the Hiss appears to be an issue in certain systems and is a limitation of the Digital Pre-amplifier Mode – however with the Balance connection you gain an extra 20dB or so (x10 lower noise). So via the Balanced connection, the Hiss is now most likely the background hiss of the Power Amps themselves.

I guess you don’t have an issue of using the Balance connection – this gives the best SQ results anyway?

If possible, maybe I could meet up with you next week, and I’d like to “Hear” the level of hiss myself, I will also bring a “known” unit with me for reference to compare (it’s the CES DQ in fact).

It looks like that we might have to start recommending to use Digital Pre-amplifier Mode “only” with Balanced Systems – off course there’s no reason why someone could not use with Single-ended systems successfully, It would just depend on there system. With our Lab System – its dead quite, you have to have your ears right-up cm’s away from the tweeters to hear any hiss.

I also have a possible idea I would like to try – but I need a “hissy” system to try on… So meeting up would be worth while…

In light of this “known issue” with this batch of units (blowing the mains fuse) – all units shipped from this batch will be covered with a Lifetime warranty related to blown Fuse issues – so no one needs to worry.

Also, once I get to the UK next week and diagnose the issue and I’ll keep everyone informed.
 
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