[Epicurean]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif why 13V, and not 12V?

Oh, that was just to get about 100mA bias on the transistors. Since there is a 0.7V voltage drop across BE the voltage across the emitter resistor is 13V - 0.7V = 12.3V. It all depends on how much bias you want and how big resistors values you use.

 

[Epicurean]

I added 470uF electrolytics after the regulators today and I'd say it is an improvement with better clarity. I chose a cheap Jamicon cap instead of a low-esr one based on this.

 

[SonicDawg]

Epicurean, have you tried the Jisbos Buffer by Steinchen yet?

 

[Epicurean]

Quote:

Originally Posted by SonicDawg /img/forum/go_quote.gif Epicurean, have you tried the Jisbos Buffer by Steinchen yet?

No. I might try some different buffers later but right now I don't feel any need for that. I don't think you can make a simpler buffer circuit than this with only 2 components per channel. The downside is that it eats a lot of current and requires sufficient heatsinking and doesn't provide any dc protection. It sounds great though. Better than anything I've heard to date, which sadly isn't very much. It is clearly better than my PPAv2 with the zapfilter single ended though which does say something.

 

[SonicDawg]

I am very tempted to try this out. But my schematic illiteracy means that I pretty much will need a printed PCB. I am also interested in Sjöström's diamond buffer. I can get 4 pcbs for about 22 dollars. Are 4 single channeled boards all I need for full balance?

 

[Epicurean]

Quote:

Originally Posted by SonicDawg /img/forum/go_quote.gif I am very tempted to try this out. But my schematic illiteracy means that I pretty much will need a printed PCB. I am also interested in Sjöström's diamond buffer. I can get 4 pcbs for about 22 dollars. Are 4 single channeled boards all I need for full balance?

Oh come on, a circuit consisting of only 3 components can't be that hard to wire correctly

. The power supply is slightly more difficult but shouldn't cause any problems if you're careful, plan ahead and remember to double check everything. I tried to do that and still put a regulator in the wrong way but it turned out all right in the end. If you haven't made anything without a dedicated pcb before you might wan't to make a simple cmoy first.

 

[Epicurean]

I had completely forgotten about this amp until today. I never finished and cased it up because of noise floor problems and the lack of a balanced pot. Today however I decided to redo the buffer using Toshiba 2sc4793 transistors instead of the bd139s. That was quick and easy and I hooked it up to my Zapfiltered Zhaolu for a test drive... and O M G this thing is just too good to be true!!! The sound is a lot better than I remember and for some reason the noise floor isn't even audible now. I feel bad to say this but this simple buffer sound better than both my beloved PPAv2 and my balanced CK2III! The clarity is breathtaking and the bass is deeper and punchier than I've ever heard through headphones. The sound is incredibly powerful and holographic.

If you own a Zapfiltered source and some Senns I recommend you try this one out! I can't imagine it sounding any better than this. There is still some dc offset on the outputs - around 5-10mVs - so I wouldn't recommend it for low impedance headphones without some dc protection.