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At last... a revised Audiolab CD/Q thread.

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JohnW said:
Pwiles,

I'd try using 4 resistors per balanced lead, with a simple Series R, and R to Ground on each of the Hot and Cold signals on the balanced line, this way you attenuate both Common mode and Differential signals. If I understand your current Lpad arrangment, Common-mode signals (such as RF and CM noise) would not be attenuated.

Also try going lower with resistor values; the CDQ's Class A Output stages have no issue with higher current - thus reducing the effects of cable capacitance and induced noise etc.

Also, place the attenuators at the Amp end, rather then the CDQ again to reduce the effects of cable capacitance and to allow the CDQ's low impedance output stage to drive the cable with authority!

John
Click to expand...

I have 4 per Lead 60k on each signal line (at the amp end) and 10k between resistor and pin going to ground which is what I think you described, so have retained the common mode rejection.

The Power amp is 100k so I am lower already, there is no induced noise at all so am OK there for now, if I ever strip them again I may reduce it a bit more is there an optimum you would suggest?

Thank you for your time once again.
 
Hi John, thanks for replying my PM.

Please keep me posted when the new transformer is available.

Glad to know that it also improves the sound quality of the CDQ/CD. :)
 
Hi, I have a 8200CDQ with software V1.1. According to Dominic one of the changes in that software was:-

added External Preamp mode on CDQ to disable internal preamp functionality (when used as a CD/DAC only).

Does anyone know how to impliment this function? I want to compare the Pre amp with my old Pink Triangle Pip2, especially using the battery mode.

At the moment I am in burn in mode with the 8200CDQ connected via balanced leads to Bryston 4B sst2 and it seems a massive change from previous Pink Triangle Ordinal/Da Capo/Pip setup.

Greatful for any advice.
 
cstanpfm said:
Hi John, thanks for replying my PM.

Please keep me posted when the new transformer is available.

Glad to know that it also improves the sound quality of the CDQ/CD. :)
Click to expand...

Great news!!!

My cdq burning in very well, just got a pair of Mogami XLRs, will test it soon. :D
 
LittleToast.

Thank you for your feedback - I'm very glad you enjoy your CDQ.

There was a small component value change after the first production batch of CDQ's - associated with the output termination resistance of the CDQ when the unit are powered off - early CDQ's terminated to Ground via 100K (when switched-off), while from the second batch onwards this was reduced to 10K to Ground. Cables with poorer shielding are liable to noise pickup when the CDQ is powered off when terminated into the higher resistance value (of 100K). It sounds like you might have an early production unit.

Yes, if the sonic performance of "CROSS" proves itself on the MDAC (we have 2 PCB versions of MDAC, one without and one with CROSS) – CROSS will be the first on the list for any MK2 versions of CD/CDQ/DQ.

Cstanpfm,

You name is among the very first on my list for the “MK3” transformer.

aybracers,

Dominik’s on his way back to China, but if my memory serves me correct, Version 1.1 does not have the external “Pre-Amplifier” mode – which is nothing more then setting the Preamplifier Mode to “Digital”, Volume to 0dB and removing the option to adjust the volume control.

So if your software version does not have the “External” preamplifier mode – then you can achieve the same result by:-

1. Setting to “Digital” Pre-Amplifier Mode
2. Setting the Volume to 0dB on the CDQ

Connecting the CDQ output to your PIP2…

If you where thinking of sending your unit back for software update, I’d hold off for a couple of months, as we should have the OLED and transformer “update / upgrades” available – and you will get the very latest software at the same time.

You say a “massive” difference between Dacapo / PIP2, in a good or bad way?

If you like the Dacapo / Pip combination, try the optimal transient filter settings.

Domho7,

How did the new cables work out?

ChrisPa

“CROSS” is a stupid acronym I thought up to “Christen and Promote” a nice little circuit / output stage topology – its stands for “Current Regulated Output Stage Solution” which I developed back in 1996/7 primary for Bias stabilisation and gain linearization around the Cross-over region of Class A/B amplifiers (not much benefit in MDAC as we operate fully in Class A), but it also has a secondary effect of dramatically improving output stage impedance and linearity – which IS beneficial in our MDAC application (atleast according to simulation and measurement results).

ADL,

Yes – correct, MK2 are in house factory manufactured versions – with modified design to improve reliability, MK3 are outside manufactured for DQ.

In brief listening tests of the DQ verses our Lab Mule CDQ reference, the DQ appears to have slightly better sound stage and Bass – and if this proves to be correct, then I can only put this down either to batch to batch variations or more likely due to the new transformer design in the DQ – so further listening is required – with the possibility of the DQ’s “MK3” type being used for CDQ/DQ (with updated windings). Nothing concrete yet – but it would be a cheap upgrade path if it proves correct.

The DQ / CDQ performance difference was not big, but there was a difference and we would like to understand why.

John
 
Any idea what sort of time frame for the MDAC John? (i'll have a 'spacey' green version if it comes any faster!) ;)

I was going to go with the DQ but seeing as its been delayed for a bit, might just wait it out for the MDAC. :)
 
Hi John,

Hope everything is good with you.

I contacted Audiolab in Huntingdon about the loan CDQ.

I spoke to someone called Tim who said would contact you to confirm everything.

Can you let me know when you have spoken to him so i can arrange to pick it up from them.

thanks again.

Richard
 
Hi John,

Thank you for your advice to get Rothwell attenuators, which helped eliminate hiss when CDQ is in Digital preamp mode.
I also got DC trap which helped a bit to reduce 8200P transformer buzz; however CDQ transformer buzz did not change much. I guess I must have an early batch unit as I also have no 12V switch and the noise pickup I mentioned before with some interconnects when CDQ is turned off is exactly what you describe for 100K-terminated early batch CDQs.

Do you think I may be eligible for transformer upgrade when they become available, and would it be possible to reduce termination resistance to 10K at the same time to reduce noise pickup ?
I am asking as I am still within my return period and could ask the dealer to try to get a newer batch. But if these small quirks could be rectified later I'd be happy to wait as otherwise I am extremely happy with this unit.
 
matyst,

Yes 100% eligible, as your transformer is buzzing - you can have the "MK3" transformer, OLED update, 100k to 10K resistor change + Software update for Free as the Transformer Buzz is a warranty issue - (you may have to pay for the shipping cost to IAG, or drop it off).

Also for transformer "Buzz" on CD / CDQ's is covered under a lifetime warrantee in the UK with the early batch transformers (MK1's) as they have proved themselves troublesome - this has been rectified on later production batches with the MK2 transformer (and hopefully MK3's).

Richard,

Ill give Tim a call Monday morning, hopefully you should be able to collect a unit by the evening :) ,

John
 
muz640,

MDAC's will be as hard to find as hens teeth upon release due to demand and limited Qtys! DQ's should be easier to find - I don’t expect the MDAC situation to ease until after Christmas - we have to be very careful with the production ramp-up, it’s a new design - with the inevitable Hardware / software issues of a complex product!

Pushing the performance / price barrier inevitably means pushing the design boundary’s - introducing more risk! MDAC is a very advance design.

John
 
JohnW said:
Richard,

Ill give Tim a call Monday morning, hopefully you should be able to collect a unit by the evening :) ,

John
Click to expand...

Hi John,

Thanks, that's great, cant wait to here it!
I'm sure it will sound great.

I have a Bryston 6B-SST and PMC OB1's So going to use the balanced inputs for the first time and will be feeding the CDQ via the USB input.

Richard
 
Hi John W,
Could you give some examples of the difference's between the M-Dac and the DQ Dac?
I am waiting for the standalone Dac and I would like the best sounding one :)

Thanks in advance.
 
ashmanuk,

DQ is based upon the CDQ but without the CD transport. It has an OLED display in place of the LCD for improved readability - also volume knob and direct source selection. The DQ also has Analogue Line-Level Pre Amplifier.

The only real complaints we get for the CD / CDQ are the readability of the LCD display and feel of the CD draw - well the DQ with its OLED display and NO CD draw so now solves both complaints :)

Sonically it should sound the same as its cousin the CDQ, but in quick listening tests, it appears to have "deeper" firmer Bass & wider sound stage. If my quick impressions turnout to be correct then its either due to batch to batch variation or more likely due to the "MK3" Transformer.

MDAC is a small format unit, 245mm wide.

It has a larger OLED display, No analogue pre-amplifier (you can use in Digital Pre-amplifier mode). I’ve not listened to the MDAC in earnest yet as its WAS based upon the CDQ – or rather the CDQ was based upon an early version of MDAC but with an internal PSU and CD servo.

As time has progressed we have learnt a lot about the ESS DAC chip and from "field feedback" from CD / CDQ – MDAC has been further developed.

If all goes well MDAC will have “CROSS” analogue stage – this is an updated analogue stage over CD / CDQ – but we have not listened to it yet on the MDAC design – Bench measurements and simulation results show great promise – but it will all come down to the listening sessions – I’m freezing up here in Scotland updating the MDAC PCB as I type this…

MDAC has a few advance features over the CD / CDQ / DQ but it will come down to what makes the bigger improvement, “CROSS” output stage of MDAC, or the better internal PSU of the CD / CDQ / DQ.

Complicating the picture further, there will be an optional upgrade PSU for MDAC released later – and also MK2 upgrade kits for the CD / CDQ / DQ to insure that they remain the leaders of the line-up "IF" the MDAC proves to leapfrog them in SQ.

So in the longer term, CD / CDQ / DQ will always have the best SQ, but there will always be competition forward between the ranges :) That’s how we will stay ahead! My intention is to enable people to upgrade there units if and when updates are available – so no one needs to feel they are missing anything and have the best…

At the end of the day, the MDAC will be reasonably cheap (under 400 GBP) – so no harm in having both – I’m sure you can always find a need for them both! (I'm sure you can hear me talking to my wife here)...

John
 
Butuz,

Thank you - as I always say, once you get comfortable with the units, do try the differant filter settings,

John
 
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