MDAC First Listen (part 00101111)

[fusion5]

What room correction software/hardware do you have in your system to fix the issue?

my measurements are very similar to yours 40hz rise and big suckout in the lower midrange

I'm using AudioVero Acourate for measurements and filter creation. Then doing online convolution with JRiver MC's 64 bit engine.

Edit: To actually perform the measurements I'm using a M-Audio Fast Track Pro USB audio interface and a Behringer ECM8000 measurement microphone. The ECM8000 was calibrated against an Earthworks M50.

 

[timola]

So I gave up my pride and ordered a pair that arrived today - very well made for GBP6!!!

I guess I have to accept I'm getting old... I just ordered a second pair as I dont want to share my pair with Jarek...

I've got mine too ..... these must be a loss leader for the supplier...excellent value for money....After seeing the detox board I'm surprised you did it without these!

 

[jarip]

John, I have received PMD100 chip from the same source as fred sonnen, whose chip you have checked and found to be ok (IIRC).

Assuming mine is also ok, can I install it into FDAC without soldering, just plugging it into a socket? Or should I send it to you to install and test?

 

[JohnW]

After seeing the detox board I'm surprised you did it without these!

I still find it easier to work without them - but they are good to QC the final PCB's.

I tried to build a PCB with them yesterday but the focal range is just to restrictive, I cannot see where I'm putting the soldering Iron back into its stand etc.

Still I'm sure I'll find good uses for them.

BTW. Your PMD200 arrived safely today - We will test on a PCB once available.

 

[JohnW]

John, I have received PMD100 chip from the same source as fred sonnen, whose chip you have checked and found to be ok (IIRC).

Assuming mine is also ok, can I install it into FDAC without soldering, just plugging it into a socket? Or should I send it to you to install and test?

Jarip,

There will be a Socket on the FDAC PCB to directly insert the PMD100 - or closer to production send it to me and I'll insert and test on your unit.

 

[JohnW]

Balanced or unalanced output for the additional channels?

Michael,

The DIC (Digital Interface Card) PCB is 70mm wide, I'm hoping to be able to squeeze 3x vertical HDMI's (2x inputs and 1x output) and if possible 2x Mini 3W XLR's for the secondary DAC channels.

 

[JemHayward]

I still find it easier to work without them - but they are good to QC the final PCB's.

I tried to build a PCB with them yesterday but the focal range is just to restrictive, I cannot see where I'm putting the soldering Iron back into its stand etc.

You really need to talk to your local optometrist about office degressive varifocal lenses. May cost more than £6 though!

 

[misterdog]

You really need to talk to your local optometrist about office degressive varifocal lenses. May cost more than £6 though!

Or welcome to the mature years as I like to think it.

Just think of all that age accumulated knowledge..

 

[misterdog]

I tried to build a PCB with them yesterday but the focal range is just to restrictive, I cannot see where I'm putting the soldering Iron back into its stand etc.

Use the force John, you know where the soddering iron stand is.

Don't look.

 

[misterdog]

http://www.basicoptical.co.za/files/How occupational lenses.pdf

So akin to trying to integrate a subwoofer with an electrotsatic full range speaker.

 

[davidjt]

Use the force John, you know where the soddering iron stand is.

Don't look.

Not how John spelt it - are you a mind reader?

 

[Jim Audiomisc]

I've only recently joined the forum and it's taken me a while to read though this thread. I've probably missed things but want to inject a few questions and comments. But to keep individual posting short and quotable I'll do it via more than one posting:

wrt HDCD I must admit I have a dislike of HDCD as it is so often abused and fouled up. And its fairly small 'gains' come via sacrificing other aspects of performance. However that said, a key point is that its main patents expired years ago. Hence there is no patent IPR preventing people doing their own HDCD decoding. I found source code for this years ago and did some simple convertor examples for Linux and RISC OS.

The snag is that the 'hf filter' details arem shall we say, a bit mysterious. I personally suspect you could make up your own preferred choices. But that said, with the HDCDs I've tested I couldn't find any sign of any encoding patterns for them in the first place.

People here may have already independently found the source code. But if not, you can find the examples (in 'C') here

http://www.audiomisc.co.uk/software/index.html

and an examination of some HDCDs here

http://www.audiomisc.co.uk/HFN/HDCD/Enigma.html

http://www.audiomisc.co.uk/HFN/HDCD/Examined.html

My guess is that wrt the 'hf' you could simply emulate the kind of thing that I believe is popular these days anyway. Switch the reconstruction filter when there is a fast transient.

Jim

 

[Jim Audiomisc]

OS:

FWIW I've been using and programming ARM devices for years. But I started and kept on from the days when Acorn invented both the first ARM hardware *and* the OS built to work specifically on it - RISC OS (RO). This has continued to be developed.

RO differs from Linux in various ways. Its much 'closer to the metal' for some purposes than standard Linux distros, and is very ARM orientated in terms of kernel and modules. It also does have a 'commercial' side as well as an 'open source' side.

Clearly not an option for the FDAC as that is well under way. But you might like to check it out for any future projects.

Jim

P.S. I'm writing this on an Arm machine running RO.

 

[Jim Audiomisc]

Jitter and Detox:

I'm not sure I've fully understood how this works. But AIUI it deliberately adds 'random' noise to the timing of the DAC conversions to try and swamp hash (i.e. signal correlated fluctuations) from the USB transfer mechanisms.

I'd need to know more about how this is done to comment on if it should work or not. But it did get my interest as it might be an area which could be probed by 'IQ test' measurements. These examine the analogue output so show the timing variations for the final output signal. Some old examples of its use is shown here

http://www.audiomisc.co.uk/Linux/Sound3/TimeForChange.html



http://www.audiomisc.co.uk/Linux/Sound4/rdac.html

But I must admit the software I released for this is awkward to use. I should do a more user-friendly version sometime.

Jim

 

[t30]

Good day to you all.
I just bought a pre-own Audiolab M-DAC. I just want to know which version is recommended to install into my M-DAC. Thanks in advance.

 

[strummer]

Apologies if this has been asked 50x before...


Is the MDAC comfortable outputing from XLR & Phono simultaneously?


One pair to Amp & the other to a Powered SUB.



ta

 

[sam_cat]

Apologies if this has been asked 50x before...


Is the MDAC comfortable outputing from XLR & Phono simultaneously?


One pair to Amp & the other to a Powered SUB.



ta

Its what I do, and asked JohnW about it ages ago and he saw no issue with doing it.

 

[strummer]

Its what I do, and asked JohnW about it ages ago and he saw no issue with doing it.

Thank you sir!

 

[davidjt]

Sorry to be the bearer of bad tidings, but see John's post 757, page 51.

 

[strummer]

Sorry to be the bearer of bad tidings, but see John's post 757, page 51.

Yesterday day I spent time listening to the Detox I connected a second subwoofer to the system via the RCA outputs of the MDAC - with the main amplifiers connected via XLR (purchased from PFM's "Furyous", thank you ).

As the RCA and XLR's outputs are shared technically its a bad idea to have "unbalance" loading on the MDAC's output stage - but what surprised me was how badly the sound quality was effected with the treble detail becoming very recessed and collapsed sound stage.

I disconnected the sub-woofers - and just had the cable connected to the RCA output of the MDAC and left unconnected at the Subwoofer end - so the MDAC was just "driving" the cable and still the sound was markedly effected so its really a big no to use both the XLR's and RCA outputs at the same time on the MDAC

I discussed this yesterday with Jarek and we will add a simple DAC to the HDMI card which can be used (but not limited to) to drive subwoofers.

We can also not populate the HDMI section so we just have a secondary DAC channel option for the FDAC.

Oh dear... Thanks for the heads up David.


OK, so I guess it's better to use a splitter cable & drive both Amp & SUB from either the Phonos or XLRs.