BiDAT/Meitner/MuseaTex/

[PHEONIX]

Originally posted by Peter Daniel
After 2 days of listening, I'm pretty much tempted to remove the caps across the diodes in digital supplies as well.

ERO1830 0.01uF seemed to work best, but even those introduced certain veiling which seems too much of a trade off for smoothness. With the caps, the sound is loosing its "freshness", when they are removed, it's like the last curtain is lifted and gains in dimentionality are well perceived. The instruments suddenly have their own space, the sounds are _really_ 3-dimentional with layers of plans much better defined.

I started voicing the circuit without those caps in a first place, it may be different if someone does it with the caps across the diodes. It is possible that removing them then, has no advantage at all.

Hello Peter

Just Curious what do you use as your reference speaker, for your evaluations. What do you also do for music do you use commercial discs.

Regards
Arthur

Regar

[Peter Daniel]

At the moment I'm using FAL drivers and Aurum Cantus ribbons with first order crossovers: Anybody tried FAL drivers?

As to the discs, it's whatever I can buy at local stores.

[Peter Daniel]

I worked today with the caps in analog regulators section. The two smaller caps on the right (originally 220/25V) are input bypas caps. I initially tried BG N 10uF but the sound thickened and lacked air and resolution. I installed ERO 10nF and this worked fine. Any cap here is in parallel with main filter caps, and since I'm using there BG N 1000/50, nothing really worked well in parallel, always adding coloration; the 10nF was still better than no cap at all.

The two bigger caps on the left, originally 470/16, were quite problematic to choose. I tried here almost everything I had available (BG N, BG FK, Nichicon FG, Elna Cerafine etc) but nothing sounded right, it was always forward, colored with tension that was hard to accept.

In the end, I installed back the original caps that were here(Panasonic SU) and suddenly everything locked in place and I got the smoothenss and relaxation I remebered so well and valued in the sound of that DAC. The certain organic quality came back and I knew that those two caps need to stay

There are still two more caps I didn't test, but after pleasant experience I had with old caps, I'm not sure I would touch those.

I also tried to remove the snubber network on transformer's secondaries (for now, in analog section only) and definitely prefered the sound without snubbers (1.5uF in series with 100R). The snubber was adding coloration without any perceived sonic advantage.

[Cobra2]

Originally posted by Cobra2
The 1547 typically has one great limitation; the internal op-amp.
But luck is that you can tap the DAC-chip in front of the op-amp...

Arne K

http://digilander.libero.it/paeng/magnetics_frame.htm

Arne K

[ash_dac]

Originally posted by Cobra2



http://digilander.libero.it/paeng/magnetics_frame.htm

Arne K

Thanks for the link.

Just to check on the tda1547 each channel of the switched capacitor outputs a standard, and an inverted signal.

So could I use it in single ended mode?

-This would increase distortion but adding an external I/V would be much more simple.
-The internal op amps seem to be referenced to ground which also makes external op amps easier to implement (rather than referenced to a 2.5V reference as in the saa7350).
-The summing amp could also be removed so only two op amps in the signal path.

Any thoughts ?

[Peter Daniel]

Originally posted by Cobra2
[B] [/The 1547 typically has one great limitation; the internal op-amp.
But luck is that you can tap the DAC-chip in front of the op-amp...B]

I am not completely conviced yet that internal amp are such a big limitation, that's why I'm leaving that tweak as last, after everything else is taken care of.

Presently my setup is similar to Level First from your link, where I'm using S&B TX102 transformers. I have coupling cap installed as the ouptut from internal op-amps carries 40mV offset.

I'm certainly interested in Second Level of modification (bypassing internal op-amps and connecting transformer directly). What are the recommneded R and C values?

And thanks for an interesting link.

[Peter Daniel]

Originally posted by ash_dac


So could I use it in single ended mode?

Yes, you can use it in single ended mode by connectig one side only of the balanced signal. I just did it two days ago, although the sound was somewhat less dynamic.

[jpak]

Peter any further mods been done to your BiDAT? Is it still your reference source?