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AK4490 USB Dac with dsd support.

If You think of real, classic Schottky diodes: then the reverse recovery snap is missing -no minority charge build-up to be conducted away. But "good" and schottky are mutually exclusive expressions, if you think of dynamic impedance terms (schottky diode internal resistance is high, current dependent. Leakage current is high. Diode reverse capacitance too.)
If You think of modern SiC diodes, the picture is much better. Also your purse gets much much more flat.
Externally, synchronously switched modern power fets are having no minority carrier problems (no P-N junction involved at all.) A resistive, low milliohm conductive channel gets inserted in the signal path - or not... much less dynamic impedance change, independent of the passing current.

So there is some playfield for getting different results.
Apart from this - I am not saying it is cure for all. But an interesting new tool. Pinocchio had ordered some boards, as far as I know. Maybe he could speak up his experience..

Ciao, George
 
TSSA 1.8

At my request, Sonny helped me make some changes to TSSA V1.8 for a headphone amplifier. TSSA is a superb amplifier and its sound is very nice. It was the same when we listened through the headphones. Total silence, crystalline voices, and the most beautiful bass I've ever heard in my headphones. Thanks a lot, Sonny!
 

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My friend Vitalica. I am happy you like it.

How about heat? Also what supply and voltage are you using.

You got rid of the nasty Mosfets.... ha ha .... Sorry... But they slow the circuit down....

I have found replacement for some of the JFET's that we use. So this circuit is like a good idea for an headphone amp. And you are really fast at implementing it Vitalica.

Thanks.

Now Vitalica runs it as a buffer and the output is common cathode. So it the headphone looks into pure current drive with current feedback as well. Looks like the resistors are 100R for the KSA1381/KSC3503 which i still have in stock. So bias is 20mA. Offset voltage is easily trimmed to a few millivolts.

For those who have them in stock i have instructions for modification.
 
Hi Sonny ,
No heat. And instead of the 100R resistors we put 47R and set a 40mA current with a 0V offset. Bias and Offset are easy to set up and are very stable. At startup I do not have any POPs.
Voltage is stabilized +/- 25V. I really like this headphone amplifier.
TSSA V1.8 I used it only in Class A with a 2A bias. An exceptional sound.
That's why I was curious as to hear this amplifier for headphones in class A. But KSA1381 / KSC3503 a max current of 0.1A, you should use other transistors ...
But with a bias of 40 mA the sound is very good, thanks a lot, Sonny :)
 
Updated USB Bridge coming to papaaa View attachment 771075
USB signature
None of the nonsense rpi problem
Naw... I'm excited

Please tell us more! :D

I have seen your email and also from a few others.

This tuesday i got my laptop stolen with my cad programs. So i have been working for several days, today it is first time my CAD program runs again on another PC.

But it have taken me 5 days. All the design files was backed up, atill there is some work to be fully running.

I will answer the emails by tomorrow.

BR

Sonny
 
Hi Sonny

Sorry to hear the mishaps. Great to hear it's up and running.

Coming in couple of months. Updated version of usbridge, good but a pain to use because the chip vendor refuse to update the firmware.I complained to allo some time back and they told me. Wait.. New product soon. But since the cat is out of bag on some other forum. No problem to release secrets.


A usbridge motherboard that host industrial cm3 rpi, without Lan or USB . Allo customises that and remove all the limitations of raspberry or general sbc

Since they can design the USB and lan. Which is very important for music streaming. They could properly design it at a higher quality thus better performance. These 2 issues cannot be solved by off the shelf sbc.

The pioneer of this method however starts from John Westlake. The products are s2 ultra project and link from stack audio. Quite expensive
But good value as they are reviewed to be at the top of USB audio. However... The software support. I don't know... But great topology and reviews...

Now. FYI usbridge. Rpi audio surpassed pc audio. Our audio buddies had tried many many solutions.. Including those who have dcs. The final answer is.. Lower powered cpu better sound. And it sounds better with a music server running miminserver or bubble upnp elsewhere in the network pre sampled . And using some sort of bridge rendering.. The sorx sampling should be elsewhere too. Not connected straight to the DAC. Thiis in confirmed by experts from top Dac maker dcs as we discussed in a local exhibition.

Thus the importance of lan quality {jitter} and the key word is galvanic isolation. Wonder why audiophile lan cable dont sound better than good off the shelf cable?. The shield is connected.. And this new mobo offers gigabit performance with better isolation.. In theory this better performance


With this new possibility... Digital audio diy or mid high end will be better than ever. So very exciting. :D:D:D:D

Cheers