SX-Amp and NX-Amp

www.hifisonix.com
Joined 2003
Paid Member
I asked what components give the cold output offset and what parameters of those components give the cold output offset.

I am NOT suggesting you redesign your NX/SX amplifiers. Nor am I suggesting you need consider adding a DC servo.

Primarily the input diamond buffers and some small contribution from the TIS - hFE and delta Vbe.
 
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hFE and Vbe both depend on Tj.
Thermal coupling of thermally matched diamond buffers would probably help with drift of temperature and drift of differential temperature.
Not sure what can be done about TIS. Maybe keeping Tj lower will reduce the warm up drift.

Any further thoughts from yourself?
 
www.hifisonix.com
Joined 2003
Paid Member
It's already low and the thermal coupling would not mske much difference with TO-92 packages.

AC coupling the feedback would almost certainly remove warm up drift, but that would not be acceptable in this design IMV - for started the low gain setting resistor would mean a very large cap.

The drift is due to second order effects - so thermal coupling wont make it go away.
 
Since Bonsai put so much effort to bring us this amazing NX Amp, it is only fair that I start posting some pictures of the final build which I'm doing now.

Here's the Amp module and PSU side by side. I wanted to minimize cable length and optimize it so not too much cabling would show up.

2014-12-27%252019.31.35.jpg


Here's the capacitors I'll be using, the other ones in the above picture was just to test the PSU. I'm configured in a dual mono setup so I will have two PSUs and two transfos or a single transfo with quad secondaries.

2014-01-25%252013.23.36.jpg


BTW, this amplifier sounds really good!

Ciao!
Do
 
Disabled Account
Joined 2012
So many great builds..... what suggestions are there to obtaining pre-punched chassis with heat sinks.... best sources are...........?? Mechanicals are my weak spot. I need as much of the mechanicals done for me as possible or I never get it built.
Chassis, heat sinks, punched holes, loaded pcb.... I do the assembly and test well. Not too much of the DIY.


THx-RNMarsh
 
Wow Thimios - that's quite a build!

I trust you are happy with the sound, and will get lots of pleasure listening to your sx-Amp (I am listening to mine now -a coustic music via Spotify!)

Thanks for posting your build pics.

Hi Bonsai i wish you a happy new year .
Thanks for sx amp.
I and my son, listening to mine continually from yesterday (always this is in on function, day and night since 30-12-14).
It is a wonderful amplifier.
Best Regards.
Thimios.
 
So many great builds..... what suggestions are there to obtaining pre-punched chassis with heat sinks.... best sources are...........?? Mechanicals are my weak spot. I need as much of the mechanicals done for me as possible or I never get it built.
Chassis, heat sinks, punched holes, loaded pcb.... I do the assembly and test well. Not too much of the DIY.


THx-RNMarsh

modushop.biz
 
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Since Bonsai put so much effort to bring us this amazing NX Amp, it is only fair that I start posting some pictures of the final build which I'm doing now.

Here's the Amp module and PSU side by side. I wanted to minimize cable length and optimize it so not too much cabling would show up.

2014-12-27%252019.31.35.jpg


Here's the capacitors I'll be using, the other ones in the above picture was just to test the PSU. I'm configured in a dual mono setup so I will have two PSUs and two transfos or a single transfo with quad secondaries.

2014-01-25%252013.23.36.jpg


BTW, this amplifier sounds really good!

Ciao!
Do

Pinnocchio
Seem like you finish your nx amp. Could you compare it to the first one. I would like to build CFA but don't know which one to build.