Opening the new DacMagic????

[wwenze]

Originally Posted by Glenn2

No harm - that is what I am actually suggesting!

The OP275 is to combine the two halves of the balanced signal to get an unbalanced one.

If it could be done your way with better sound quality, why would the designers still put the OP275? Surely there's something missing. Impedance matching maybe?

[Glenn2]

An extra few dB of s/n ratio for the spec sheet perhaps.
When you put the +ve an -ve phases into a differential amp, you get twice the signal coming out (the signal is lowered again, but also is the noise).

Other than that I don't know.

Also see:
http://db.audioasylum.com/cgi/m.mpl?...gital&n=141041

[FauDrei]

Originally Posted by Glenn2

You are just taking the signal from a different socket - why would you need to cut anything? You don't even need to open the unit for this.

Ah, I understand now.

But since I connect XLRs to one headamp and RCAs to other headamp, I should, most probably, need to desolder original RCA contacts and connect them internally with pin 1 & 2 of appropriate XLR socket.

Thanks Glenn2

[le´flu]

Hello,

things are on progress....did anyone change the l7805 for the Dac Chips
to something better? Maybe changing to reg like paul hynes is selling.

Anybody who changed the X3 clock to something better like from tent
labs?

And last question goes to glen2
you really changed the transformer so 9V? I did not measure all the
voltages but why didn´t they build in the 12V instead?

Greetings Ulf

[Glenn2]

If you mean why did they not put the transformer inside the box, I guess it's to make the unit smaller...

[le´flu]

Hi Glen2,
no the question is: why did they use a 12 Volt transformator
if the dacmagic also works with a 9 volt one like you wrote?

[Glenn2]

9V would not give enough headroom for the output stage regulators if your mains line voltage is on the low side. Mine is usually around 250V.

I get +19V/-20V going into the 7815/7915 which is perfect.

The + rail sags a bit more then the - because the load is heavier (it powers the 7805 for the DACs).

If my mains was 230V I would get more like +17.5V which is very near to the minimum dropout voltage. If you go below 230V...

[bingo10]

Originally Posted by Glenn2

... I made my own adaptors as I didn't want the negative phases shorted to ground like they are in some shop-bought XLR->RCA adaptors (intended for balanced amp inputs).

Originally Posted by Glenn2

The OP275 can be bypassed simply by taking your signal from the XLR sockets instead of the RCA sockets.
Pin 1=Gnd, Pin 2= + phase, Pin 3 = - phase.
So take signal from pins 1 and 2 and leave pin 3 alone.

Hello Glenn2!

I just bought DacMagic and read your post about improving the sound with XLR/RCA adaptor.

You saying take signal from Pin1 & Pin2 and leave Pin3 alone. In my local store I can buy good quality adaptor for very resonable price but unfortunately it has Pin 3 grounded (like most other adaptors on the market) and it can't be taken apart for modification.

So I wanted to ask if the adaptor with Pin3 grounded is really such a bad solution? Will it degrade the sound compared to adaptor with Pin3 alone?

Sorry for my loussy english and thank you very much for your answer!

[Glenn2]

Hi, sorry I did not see this or your pm (I rarely get notified for some reason).

If you use this adaptor, it will make the RCA sound distorted, see this thread:

Cambridge DACMagic, anyone? (THREAD II) - Page 22 - Head-Fi: Covering Headphones, Earphones and Portable Audio

If you don't need to use the RCA as well you should be OK. By shorting pin3 you are making the unused op-amp drive a very low impedance.

[bingo10]

Thank you very much. Now clear.