At last... (Audiolab) - part V

[Steven Toy]

. The M-DAC's CROSS output stage is a full blown Class A preamplifier sporting near zero output impedance. There is really no reason to daisy chain another preamp, just like you wouldn't consider running two separate preamps in a typical system.

This is interesting although I do remain sceptical. The CDQ was claimed not to need a separate preamp but the valve grounded grid is still in line doing a sterling job of improving dynamics, authority, making the sound stage more three-dimensional and improving musical timing.

I am considering getting it re-built with a better, more modern and quieter toroidal transformer, removing the one capacitor so that it is directly coupled throughout and having it housed in a non-ferrous box.

However, if, as you say, a separate preamp is not needed and my ears agree (entirely possible) then I will save my money.

 

[JohnW]

I guess the simple answer is that if I can get a PCM (is that the right term?) front L/R digital signal from "somewhere" into the MDAC, then it's possible to do the pass-through?

Yes - and you will also gain the benfit of MDAC's higher quality on your AV sound tracks (atleast for the L/R channels).

Can the volume setting on the digital inputs on the MDAC be trimmed independantly like the CDQ analogue inputs? You might remember I have an issue where I need to use attenuators from the CDQ to the X7 which causes the knock-on effect that there is then not enough range in the trim settings on the AP for me to raise the level of the fronts sufficiently to match the surrounds.

Following our "Panic" drive across Europe last year to have a listen to the Hiss in your system - with the CROSS analogue stages, we have improved the MDAC's Dynamic range by close to 15dB over the CDQ. This brings the MDAC's single-ended outputs (RCA's) just a few dB shy of the CDQ’s performance via its Balanced connections, and I believe (Hope!!!) that this will now resolve the Hiss issue for everyone.

John

 

[JohnW]

John/Dominik - Is the volume control on the MDAC analogue or digital? If it is digital, would it be better to run it into a separate pre-amp, especially for low level listening, or is it best connected straight to a power amp (or active speakers)?

As Dominik has already answered, there’s little point in running two pre-amplifiers in a system. However, depending on your systems sensitivity (and many other factors) - I can see different reasons why using external attenuators between the MDAC your power-amps to keep your volume control usage to between say +3dB to -25dB would be beneficial. My leading thoughts on the advantages of external attenuation (Such as the Rothwell inline attenuators) :-

1. Attenuates the RF levels between the MDAC's outputs & your amplifiers sensitive input stages (This will reduce any Glare / Hardness).

2. Keeps the DAC operating within its most "Linear" region (NOT THD, but digital rounding errors, Analogue SNR etc).

John

 

[AndyU]

John and Dominik - thank you both for such helpful replies. The way you answer questions online is in a completely different league from any other manufacturer I've encountered.

I suppose a way of reformulating my question is: would you prefer an MDAC -> 8200P or an MDAC -> 8200Q -> 8200P? Or an MDAC -> Rothwell -> 8200P?

 

[JohnW]

The difference the Danish model makes to the foobar/ASIO4ALL feed from an old Thinkpad X41 is marked - loads more detail and timing. No question it's worth the Euros 46.79 to have it delivered from http://www.electronics-shop.dk/galvanically_usb_isolation.htm?currency=EUR

Hi Duncan,

Well that seems to be the general consensus - Its why I recommend to buy the Isolator instead of spending on worthless "Boutique" USB cables (which often cost more then the isolator!!)

Thank you...

John

 

[JemHayward]

But I tell you what - been thinking about the obvious need to be able to select between MDAC output and some Analogue pass though mode - we could added the feature to the external PSU box - so that its a PSU + Audio Pass though selector - there is a Comms Bus link on the PSU connector to facilitate this - I'm guessing this would be ideal?

John

If you can build "intelligent" PSU units, 1. I may not DIY, and 2. How about either a really good ADC so we can route analogue sources through the M-DAC or a passive preamp that tracks the volume control on the M-DAC?

Or you could produce a selection of "modules" that sit between the M-DAC and the PSU to suit different needs, but primarily mine, of course

 

[bottleneck]

There is really no reason to daisy chain another preamp, just like you wouldn't consider running two separate preamps in a typical system.



Dominik

Surely this does not apply to people with analogue phono stages, analogue tuners, reel to reel etc.

 

[Steven Toy]

The proof of the pudding....

 

[JohnW]

Surely this does not apply to people with analogue phono stages, analogue tuners, reel to reel etc.

Of course I was refering to Digital only systems....

The MDAC can be set for "Pure" Dac mode (Fixed Line Level DAC) - or with Digital Pre (Variable Output).

John

 

[JohnW]

The proof of the pudding....

Indeed, with audio there are so many different factors to take into consider, that one can only generalise, however at the end of the day it boils down to listening – as you say the proofs always in the pudding…

 

[nbc]

Hi John,

Can you tell me more about the analogue pass through you may incorporate into the psu.

"select between MDAC output and some Analogue pass though mode"

Is the idea that you could connect an analogue input from say an av front L+R pre out and this signal would then be able to be routed through the MDAC analogue outputs?

I dont quite get how the analogue signal would pass from the psu to the MDAC, also could an rca analogue input be output by xlr at the MDAC?

Any solution that would allow another analogue input to be routed to the power amp via the mdacs analogue outs would be ideal

Its always niggled at me that way back when you were asking for suggestions for features you could incorporate into the dacs I didnt suggest an av pass through for the mdac, my thought was that unlike a fixed line level input a front av input has its level set by the av preamp so no attenuation/gain is required and could be passively routed through without the need for an an analogue pre in the dac.

PS
Did you get my pm for a silver unit? I'm not sure if your inbox was full when I sent it during the feeding frenzy

 

[scubaboy]

Streatham eh.... i remember sharing a flat there for a few months some years ago. Can't say i have particularly fond memories of SE London.
Just wondering if you managed to check your DC unit to see if it would be possible to use as the power supply for Mdac? A clear out needs to take place in the near future and DC would have to go, all other Pink units in Pink heaven.

 

[JohnW]

If you can build "intelligent" PSU units, 1. I may not DIY, and 2. How about either a really good ADC so we can route analogue sources through the M-DAC or a passive preamp that tracks the volume control on the M-DAC?

Or you could produce a selection of "modules" that sit between the M-DAC and the PSU to suit different needs, but primarily mine, of course

We have things in the works on the Pre-amp side...

Tim’s posting last night spurred me into deciding to add a Pass-though option on the external upgrade PSU...

John

 

[JohnW]

Hi John,

Can you tell me more about the analogue pass through you may incorporate into the psu.

"select between MDAC output and some Analogue pass though mode"

Is the idea that you could connect an analogue input from say an av front L+R pre out and this signal would then be able to be routed through the MDAC analogue outputs?

I dont quite get how the analogue signal would pass from the psu to the MDAC, also could an rca analogue input be output by xlr at the MDAC?

Any solution that would allow another analogue input to be routed to the power amp via the mdacs analogue outs would be ideal

Its always niggled at me that way back when you were asking for suggestions for features you could incorporate into the dacs I didnt suggest an av pass through for the mdac, my thought was that unlike a fixed line level input a front av input has its level set by the av preamp so no attenuation/gain is required and could be passively routed through without the need for an an analogue pre in the dac.

PS
Did you get my pm for a silver unit? I'm not sure if your inbox was full when I sent it during the feeding frenzy

Hi NBC,

Yes your on the list, A silver unit with collection from Hi-Fi corner.

The external "Passthough mode" built into the upgrade PSU module would select between the MDAC's outputs & an external analogue input (such as your AV reciever).

Yes, I'm planning the you can connect either Single-ended input (RCA) which then would be converted to Balanced (with also a balanced input) and then being able to select between these and the MDAC outputs - so ideal for your AV system.

John

 

[JohnW]

Streatham eh.... i remember sharing a flat there for a few months some years ago. Can't say i have particularly fond memories of SE London.

You and me both - its truly a horrided place. I've lived and work all around the world, and the only place where I'm worried to walk the streets at night is SE London.

Just wondering if you managed to check your DC unit to see if it would be possible to use as the power supply for Mdac? A clear out needs to take place in the near future and DC would have to go, all other Pink units in Pink heaven.

My DC's in China (I'm still thankfully in Czech for a few more days or so) - but Keep your DC, we will get it going with the MDAC... (Somehow). I'm interested to compairing DC operation with the "offcial" External PSU (which I'm going to start designing today).

John

 

[chris shorter]

I'm still thankfully in Czech for a few more days or so........

John

John

I live near Teplice in the Czech Republic, so presumably I am a bit out of range of your kind offer to PinkFish members?

Have you any idea how long it will be before MDAC's begin to filter through to the Czech Republic or accessible dealers in Germany?

Many thanks

Chris

 

[arthur]

I'm interested to compairing DC operation with the "offcial" External PSU (which I'm going to start designing today).

John

Hi John. I really must insist that you take at least a WHOLE DAY off soon.

Can't have you exploding before you've built the next gen' LakeWest dac!!

Or at least one for me

 

[JohnW]

John

I live near Teplice in the Czech Republic, so presumably I am a bit out of range of your kind offer to PinkFish members?

Have you any idea how long it will be before MDAC's begin to filter through to the Czech Republic or accessible dealers in Germany?

Many thanks

Chris

Hi Chris,

I have no idea who the Audiolab dealer is in Czech Rep. they have never bothered to make contact with me - so they sound like a waste of time...

If your really interested in one, then I can bring one over for you - hey maybe I can become the Czech Distrubuter - and then I can complain to the designers.. wait how would that work?...

PM if your really interested - and I will arrange something for you.

Good to meet a fellow Pink Fisher from Czech Rep... I thought I was ALL alone...

John

 

[JohnW]

Hi John. I really must insist that you take at least a WHOLE DAY off soon.

Then I would fall asleep.... No tme for that...

 

[Interzone]

Bought WHiFi to check out the mdac review today (£4.65, what a rip-off). It sounded like they wanted to give it 6/5 (or 5/5 and the rest 4 or less) but didn't want to annoy other manufacturers (advertisers).

John, is it still looking like mid october for the mdac?