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MDAC first listen (part XI)

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Been away for a bit - what's the latest firmware and what benefit would it bring to my MDAC over v0.99 (which is what I have right now)?

Also, any rough timescale for the MPAX, John? I know that you've probably answered this somewhere recently but buggered if I can find it...

The latest one is A08 and everything is on the M-Dac wikii, as for the MPAX it will be available around christmas..
 
Been away for a bit - what's the latest firmware and what benefit would it bring to my MDAC over v0.99 (which is what I have right now)?

Also, any rough timescale for the MPAX, John? I know that you've probably answered this somewhere recently but buggered if I can find it...

A couple of months after MAMP - so the first few months of the New year - MAMP is targeted for Christmas...

John
 
I got a second MDAC now ... this way, when I send one back to John W for mods, I'll still have one at home ....... Looking forward to the MPAX ....

:) maybe I can update your unit during the CES - if I go this year...

John
 
I think the big advantage of a touch over direct connection is that the touch is wireless and you can run many of them simultaneously. It also runs stand alone , no server required and does not mess with bitrates etc..
As to the chap that asked about the Brio amps vs Audiolab , well I have had both the 8000 and the 8200 Mb's in my system , I feel the MB's beat a Bryston 4B ST and the 8000p's were pretty good, both very "truthful" amps , so if you want a "romantic" sound , they aren't for you.
JohnW , I have a question for you , A local chap , now deceased built what is called a "constant Z attenuator , its a passive pre , remote controlled , What exactly is "constant Z"? and what are it's advantages. I have opened it up , see a ton of chips but no attenator (like an alps) ....
PS I think the best feature in your software upgrades is the ability or delete filters for comparison purposes ...

If you post an internal picture of your pre-amplifier then I can tell you how it works.

Constant Impedance attenuators are design not to change there input or Output Impedance (or Both) as you adjust the attenuation level - a good idea IMO.

Input impedance can effect the sound quality due to loading of the source device plus cable effects - likewise output impedance can effect the SQ due to cable and input stage loading effects - having the impedances constant should in theory remove a potential variability in SQ as you adjust your listening level...

Any effects will be dependent upon your system...

John
 
Input impedance can effect the sound quality due to loading of the source device plus cable effects - likewise output impedance can effect the SQ due to cable and input stage loading effects - having the impedances constant should in theory remove a potential variability in SQ as you adjust your listening level...

John - load impedance effects on well-designed modern kit ought to be absolutely minimal. When you adjust the level of a signal, the biggest single variable as far as sound quality is concerned is the human ear's changing characteristics with varying level...Fletcher Munson etc.
 
Do you expect the MAMP to drive Martin Logans when bridged? (if my understanding of bridging is correct, each amp will then see only half the impedance, so the current demand could be huge!) - I don't think I'm going to need the power for my Summits, but I quite like the idea of placing the amps behind each speaker, or even perching them on top of the bass bin - may look cool... I think they will make an interesting comparison with my EAR890.

Well I'm intending the MAMPS will drive my ML CLS11z - these are the worst amplifier load ML have ever inflected - so I'll discover how well they cope in Bridge mode - if they work well with my CLS's then there should be no problem driving your summits...

The MAMPS have 10 output devices per channel - peak current should not be an issue... protection is currently set to kick in around +/- 45amps - although higher shorter term peaks will be allowed... I'll hopefully soon see (hear) what this translates too in real life operation...

Can you Bi-Amp your Summits (rear Bi-Wire terminals)?

John
 
John - load impedance effects on well-designed modern kit ought to be absolutely minimal. When you adjust the level of a signal, the biggest single variable as far as sound quality is concerned is the human ear's changing characteristics with varying level...Fletcher Munson etc.

Not sure I agree - changing input impedance of a Pre-Amplifier can result in a significant change in SQ - I'm not sure if its due to the loading of the source device or "termination" of the interconnect cable... Low input Z seems to improve SQ - which tends to suggest the interconnect cable being the biggest factor... (lower Z in theory should worsen the performance of the source device).

John
 
Question for John, If you would be so kind.

I have had a an M-Dac for just over a week (from Movement Audio Poole)
Front Panel now shows "No Comms" and has ceased to function.
The unit will be swapped for a new M-Dac so no problem with warranty.
Just interested to know what could have caused this.
Unplugged laptop HP Pavilion DM1 (to use at my daughters wedding)
Returned home, plugged in same USB lead and now "No Comms"

Stuart

My first post so forgive me if I have breached protocol.

Sorry to hear about your problem with your MDAC, the first suspect would be a failed Crystal in the MDAC clock circuit - this is the most common single point of failure with the MDAC - but its well under 1%...

Audiolab have recently changed vendor of the Crystals - so hopefully this will help to improve the situation in future production...

The MDAC places a very high demand on the quality of the Crystal - its a balance between cost and reliability... If we still worked at Audiolab we would have look into improving this aspect of the design based upon mass production and service feedback - however the rest is history...

John
 
Hi JohnW,

What stops you from having bigger heatsinks with more surface area in your design?
 
No Coaxial connection? I thought, that was better!

The MDAC is Clock master (the Transport is slaved to the MDAC clock by the second optical link, so any jitter introduced by the optical link is irrelevant at the point of audio conversion - but very importantly you gain the benefit of galvanic isolation afforded by the optical connection (With USB this is very beneficial as it isolates your audio system from your EMC (RF) noisy PC / USB Host device)...

John
 
Hi JohnW,

What stops you from having bigger heatsinks with more surface area in your design?

The intention is to match the MDAC footprint - and there's only so tall we can make them... at the moment the MAMP is x2 as tall as the MDAC...

John
 
Hi John,

With 2 MAMPs, will it be possible to use one amp per speaker, i.e. in a monoblock style configuration, or use one to drive the highs and mids, and another to drive low freqs, or all of the above?

Do you envisage much of an SQ improvement in using 2 over 1 in either configuration?

Many thanks,

James
 
The MDAC is Clock master (the Transport is slaved to the MDAC clock by the second optical link, so any jitter introduced by the optical link is irrelevant at the point of audio conversion - but very importantly you gain the benefit of galvanic isolation afforded by the optical connection (With USB this is very beneficial as it isolates your audio system from your EMC (RF) noisy PC / USB Host device)...

John

OK. Thanks. I'm considering buying the MTRN. But now I'm using the MDAC with the MF M1CDT transport.
 
Hi John,

With 2 MAMPs, will it be possible to use one amp per speaker, i.e. in a monoblock style configuration, or use one to drive the highs and mids, and another to drive low freqs, or all of the above?

Do you envisage much of an SQ improvement in using 2 over 1 in either configuration?

Many thanks,

James

On other PFM threads there's often been discussions about the merits of bi-wiring, with the general consensus that it does not make much of a difference - however my experience has proved otherwise - maybe I'm hyper critical...

Bi-Amping takes Bi-Wiring to the next logical level.

I've also found that Bridged power amplification when done correctly has a dramatic effect upon the Bass performance - resulting in much greater "Impact" to the Bass...

The MAMP allows all modes of operation - and will automaticly compensate for the extra 6dB of Gain when in bridge mode.

I'm going to wait before passing any comment until I have a chance to listen for myself :)

John
 
Sorry to bring this one up again but when performing the bitrate test, it seems to be fine all the way to the end where it reads that the test passed and then immediately after, says that the test failed?!? Is this normal behavior or do I have a problem somewhere? Anyone else experiencing this?

Cheers,
Vin.
 
Sorry to bring this one up again but when performing the bitrate test, it seems to be fine all the way to the end where it reads that the test passed and then immediately after, says that the test failed?!? Is this normal behavior or do I have a problem somewhere? Anyone else experiencing this?

Cheers,
Vin.

Yes, that's totally normal - its just indicates "Failed" once you stop the Datastream because the input "Data" no longer matches the expected bit pattern.

John
 
Well I'm intending the MAMPS will drive my ML CLS11z - these are the worst amplifier load ML have ever inflected - so I'll discover how well they cope in Bridge mode - if they work well with my CLS's then there should be no problem driving your summits...

The MAMPS have 10 output devices per channel - peak current should not be an issue... protection is currently set to kick in around +/- 45amps - although higher shorter term peaks will be allowed... I'll hopefully soon see (hear) what this translates too in real life operation...

Can you Bi-Amp your Summits (rear Bi-Wire terminals)?

John

Yes, my Summits have two sets of sockets, though I don't bi-wire or bi-amp them. I asked ML about this, and they said that it would make no difference as the power amp driving the bass end is just driving another power amp, so has very little work to do. The reason they offer the facility was "fashion".
However if I end up using two M-AMPs as monoblocks for convenience/aesthetics I can try both bridging and bi-amping. The Summits are pretty efficient and the room isn't that big, so I don't need much power - my EAR is about 70w and that is more than plenty.
 
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