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MDAC First Listen (part XXIX)

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fusion5 said:
Pics or didn't happen :D
Click to expand...

Well its "happening"... :)

Got a few small bugs to iron out, but nothing that's not to be expected at this stage of development :)

https://dl.dropboxusercontent.com/u/86116171/Mdac2 test.JPG

I've built one the four identical ClassA sections for testing - the Mosfet power output devices + heatsinks are mounted on the underside of the PCB to allow clearance while testing & tweaking the design (they would normally be mounted on the PCB topside - but would cover the smaller SMD components below).

Measured performance exceeds the capabilities of my test equipment (not that this is a reliable matrix for sound quality).

THD into 75 ohms below 0.00008% and very stable ClassA Bias stability...

Working to resolve a few small issues... :)
 
To while away the time waiting for John's update, does anyone have any experience of these, or similar, units:

1. http://www.project-audio.com/main.php?prod=phonoboxusb&cat=boxes&lang=en

2. http://www.project-audio.com/main.php?prod=phonoboxusbv&cat=boxes&lang=en

My intended use is to connect one between my turntable and M-DAC in order to listen in real time, not to record to hard drive. Is that possible with these devices. Would anyone recommend any other devices over these for that purpose?
 
You cannot connect two slave devices.

The MDAC requires a host device (pc) to function properly as do this device.
 
highfi said:
To while away the time waiting for John's update, does anyone have any experience of these, or similar, units:

1. http://www.project-audio.com/main.php?prod=phonoboxusb&cat=boxes&lang=en

2. http://www.project-audio.com/main.php?prod=phonoboxusbv&cat=boxes&lang=en

My intended use is to connect one between my turntable and M-DAC in order to listen in real time, not to record to hard drive. Is that possible with these devices. Would anyone recommend any other devices over these for that purpose?
Click to expand...

Haven' heard the Phono amp yet, but getting very good reviews, I have some other good stuff from them, and going to get one myself
Cheap line from AMR (Thorsten Loesch is engineer)

but you will need a AD converter also

http://www.ifi-audio.com/en/iPhono.html
 
No - I have other Cyp products and they seem to be well made - I've certainly seen them for sale in Hi-Fi shops. My main concern with that product is that there is no control of the input gain, so that is why I was thinking a S/H MiniDisc off EBay might make a reasonable (and cheap) ADC. When I had my Turntable set-up, I was able to make pretty good recordings via MiniDisc. I did dig my MD out and hook it up to my M-Dac once, to see if it could be used this way (as an ADC). M-Dac showed a 20bit/44.1kHz signal from the MD. As MD are of little value, I'm personally going to hang on to mine in case I ever need an ADC.

No doubt someone will pop up saying that MiniDisc is a lossy format, but used purely as an ADC - I think you avoid the lossy part.
 
Just a quick update, solved one of the 2 issues (I'll give more details later) & even managed to improve the design...

Measured results even at this early stage are stunning - 0.00005% THD 2.5Vrms into 33ohms load (the lowest headphone load) @ 1KHz... in fact there's no change in distortion with the 33 ohm load connected or not...

I'm beavering away here in the lab - so pls. forgive the lack of post - I'll give a full write up once I'm happy with the design..
 
The coding on minidisc is hardwired, all digital going in or out of a minidisc has been processed as a lossy file. With the later HD recorders this might not be that lossy, but lossy all the same.
 
JohnW said:
Just a quick update, solved one of the 2 issues (I'll give more details later) & even managed to improve the design...

Measured results even at this early stage are stunning - 0.00005% THD 2.5Vrms into 33ohms load (the lowest headphone load) @ 1KHz... in fact there's no change in distortion with the 33 ohm load connected or not...

I'm beavering away here in the lab - so pls. forgive the lack of post - I'll give a full write up once I'm happy with the design..
Click to expand...

Well, it seems like a very awesome start on the figures side.
:)

Michael
 
JohnW said:
Just a quick update, solved one of the 2 issues (I'll give more details later) & even managed to improve the design...

Measured results even at this early stage are stunning - 0.00005% THD 2.5Vrms into 33ohms load (the lowest headphone load) @ 1KHz... in fact there's no change in distortion with the 33 ohm load connected or not...

I'm beavering away here in the lab - so pls. forgive the lack of post - I'll give a full write up once I'm happy with the design..
Click to expand...

Looking forward to this :)
 
Would John or anyone help me with a hyperlink for paying the 2nd (2nd?) installment, I really have tried to look for it in the forum and also with google but the original wiki link seemed not working anymore, thanks.:)
 
@Rune,

Any initial impressions of the Khozmo passive as pre with MDAC as DAC you can share with us.
Love to hear what you're experiences are so far since I'm on the same journey.

Cheers

/Lars
 
Yes you are, moaning ... How long is a string? could be the answer to your question ... ;-)
Bear with those of us waiting and longing for LakeWest's MDAC2.
 
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