advertisement


MDAC First Listen (part 00100000)

Status
Not open for further replies.
fred sonnen

fred sonnen

pfm Member
JohnW said:
But no problem to clocklock the MDAC to any source - I know someone has a modified TEAC CD transport clock locked to the MDAC :)
Click to expand...

Hi John

Did you have mor info/ link?
I expect your MTRAN earliest late 2015. So It could be a solution...
 
fred sonnen said:
Hi John

Did you have mor info/ link?
I expect your MTRAN earliest late 2015. So It could be a solution...
Click to expand...

The MDAC can be locked to Arcam / Deltec / DPA or any CD transport that allows locking to 96Fs, 128fs, 256fs or 384fs clock.

Sorry, the original post is buried in these threads a year or 2 ago now...
 
adamdea said:
All OT filters have the same response

http://www.hi-fiworld.co.uk/index.p...iews/642-audiolab-q-dac-filters-.html?start=1

[As I understand it the M-dac and Q-dac filters are the same.]

See also Paul Miller's measurement of the M-dac.
http://www.milleraudioresearch.com/download2012/reports/yb12/audiolab_mdac.html
Click to expand...

Interesting, I'm not sure how correct the OT time domain graphs are as there should be no Pre or post ringing at all.

The QDAC was used for the measurements - Audiolab might not have reversed engineered our filters correctly, indecently we own the IP on the various custom filters - Audiolab should not have been using them at all without agreement, but life is too short to deal with such people.

It might just be a measurement issue... What do the Paul Miller time domain plots show with the MDAC?
 
adamdea said:
I should admit that I was being a bit flippant and that the roll off is not the same as that house curve (the house "curve" is more like a straight line whereas the OT really is a curve). The OT might well be quite similar to a NOS dac.
Click to expand...

The OT filters are in effect NOS....
 
I'm happy when magazines go to such depth in analysing the filters as I believe the root cause of PCM audio s lack of realism (compared to Analogue masters / DSD) is PCM's filtering structure's.

The more discussion on the subject the better IMO :)
 
adamdea said:
I'm rather hoping that with the M-dac 2 you will be implementing at least as an option I nice orthodox linear phase windowed sinc filter (sort of souped up Optimum Spectrum) for people like me who can't help themselves.
Click to expand...

With the MDAC we are limited to the ESS's filter structure but with the MDAC2 we have the FPGA and DSP so digital filters options are limitless :) I'm personally looking forward to "Playing" with many filter ideas :)

I can see a constant barrage of filters for everyone to try if they are interested.
 
rtrt said:
So does Optimal Transient XD similarly roll off the treble? If yes does anyone have a graph/some more detail pls?
Click to expand...

Its my opinion that the time domain is far more important then the frequency domain.... although one would hope not to see any abrupt discontinuities in the frequency domain (and would not normally be possible with a clean Time domain).
 
JohnW said:
Interesting, I'm not sure how correct the OT time domain graphs are as there should be no Pre or post ringing at all.

The QDAC was used for the measurements - Audiolab might not have reversed engineered our filters correctly, indecently we own the IP on the various custom filters - Audiolab should not have been using them at all without agreement, but life is too short to deal with such people.

It might just be a measurement issue... What do the Pual Miller time domain plots show with the MDAC?
Click to expand...
They show it as being without any ringing as we would expect from a NOS, ie in effect no filter at all (although with a delta sigma dac you need to have a filter to reproduce the slight HF drop on the filterless sample and hold).

I agree that the Hifi World picture of the impulse response is very surprising, and made me wodner whether the author knew what he was doing.

It's interesting that the Watts 26k tap filter must by definition ring (in this sense) for over 1/2s of a second. Although how much of that ringing is actually time smear as opposed to genuine reproduction is open to debate.

Anyway it's definitely nice to have the choice.
 
adamdea said:
They show it as being without any ringing as we would expect from a NOS, ie in effect no filter at all (although with a delta sigma dac you need to have a filter to reproduce the slight HF drop on the filterless sample and hold).

I agree that the Hifi World picture of the impulse response is very surprising, and made me wodner whether the author knew what he was doing.

It's interesting that the Watts 26k tap filter must by definition ring (in this sense) for over 1/2s of a second. Although how much of that ringing is actually time smear as opposed to genuine reproduction is open to debate.

Anyway it's definitely nice to have the choice.
Click to expand...

No the rolloff is the natural sin(x)/(x) response of a NOS filter (we perform no Frequency response tailoring) - it doesn't matter what DA conversion technology is used - this is after the fact...
 
Dominik has some ideas about the 26K filter that it might not be a true 26K tap filter - but I was not paying attention... This damn PCB has made me go alittle "one track minded"....

The good thing is we can replicate what ever the "Watts 26K" filter does on the MDAC2 for comparisons :)

It looks like you and Dom will have much to "discuss" :) As long as your prepared to trust your ears rather then "technical" superiority... mind you lets see if we can make them go hand in hand!
 
JohnW said:
I can see a constant barrage of filters for everyone to try if they are interested.
Click to expand...

Happy to acknowledge that I find it difficult to hear small differences on loudspeakers, but can more often hear them on headphones.

In the past I've wondered if i had a dedicated listening room, that was set up properly, whether i'd find it easier.

Then i realised that since a new house wasn't coming any time soon, i should just stop trying so hard, pick a setting - maybe with a different one for headphones and just get on and enjoy the music :D
 
JohnW said:
Its my opinion that the time domain is far more important then the frequency domain.... although one would hope not to see any abrupt discontinuities in the frequency domain (and would not normally be possible with a clean Time domain).
Click to expand...

Much of what you and Adam are discussing is over my head John - maybe 25 years ago i'd have been able to understand, but signal processing was tough going then never mind half a lifetime later :confused:

Having said that I appreciate choice/flexibility in most things - so I'll be going for the full fat MDAC2 :cool:
 
JohnW said:
No the rolloff is the natural sin(x)/(x) response of a NOS filter (we perform no Frequency response tailoring) - it doesn't matter what DA conversion technology is used - this is after the fact...
Click to expand...

Of course, that makes sense. That leaves me trying to get my mind round what the OT filter actually does (if it doesn't actually filter).
 
JohnW said:
Dominik has some ideas about the 26K filter that it might not be a true 26K tap filter - but I was not paying attention... This damn PCB has made be go alittle "one track minded"....

The good thing is we can replicate what ever the "Watts 26K" filter does on the MDAC2 for comparisons :)

It looks like you and Dom will have much to "discuss" :) As long as your prepared to trust your ears rather then "technical" superiority... mind you lets see if we can make them go hand in hand!
Click to expand...

I would enjoy that discussion.

John Swenson has posted on several occasions that he thought that people like NOS dacs because the regular hardware filters were no good, and that he thought that a properly implemented (on FGPA or in computer) windowed sinc filter sounded best.
 
adamdea said:
Of course, that makes sense. That leaves me trying to get my mind round what the OT filter actually does (if it doesn't actually filter).
Click to expand...

NO! but the trick was trying to implement it on a DAC where we could not bypass the filter in the conventional sense!
 
adamdea said:
I would enjoy that discussion.

John Swenson has posted on several occasions that he thought that people like NOS dacs because the regular hardware filters were no good, and that he thought that a properly implemented (on FGPA or in computer) windowed sinc filter sounded best.
Click to expand...

Well indeed, the MDAC2 is the platform we can experiment "in Public" :)
 
adamdea said:
I agree that the Hifi World picture of the impulse response is very surprising, and made me wounder whether the author knew what he was doing.
Click to expand...

WRT the Minimum phase & OT filters we suspect we are looking at the UPV FIR filter in its ADC and not the impulse response of the QDAC and it does appear that Audiolab China have "helped themselves" to our filter design IP.
 
Status
Not open for further replies.


advertisement


Back
Top