My Take on Threshold NS10

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#122
Some people want to try a FET for Q1. There is no change needed in biasing it.
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Thanks a lot, Tom 🙂

Is there a NS10 PSU schematic around I´missing?
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JC, there was no psu posted yet, but someone will eventually😀

Here is a pic of the proto boards in the making. No fancy parts yet. The first test will be to see, if this works at all😀 Dont let Q2 confuse you, I have used a BC560C, which has a different pinout than the MPS4250.
Where is best to wire the pot, for a circuit like this. Input or output?

Steen😎
 

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#125
Re: NS10 PSU schematics

JC Fardo said:

Is there a NS10 PSU schematic around I´missing? What could be the trafo VA rating?
JC
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I will propose a PSU soon. A double rail regulated supply similar to other Pass projects.

The actual demand of the circuit is very low so a small trafo will do, some 20/30 VA for both channels is enough.🙂
 
#128
Tom, yes thats the tonertransfer method. Here is a link with a really good description of the process. The paper I used is called OCE glossy photo paper, IJ570. It was bought a couple of years ago, but I am not sure I can get that paper again.

http://www.fullnet.com/u/tomg/gooteepc.htm

Russ, thanks for the schematic. Yes that etch turned out pretty good. There is no problems populating the boards, so no muckups yet😉 Here is a closer pic of the boards.

Steen🙂
 

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#130
steenoe said:
Here is a pic of the proto boards in the making. No fancy parts yet. The first test will be to see, if this works at all😀 Dont let Q2 confuse you, I have used a BC560C, which has a different pinout than the MPS4250.
Where is best to wire the pot, for a circuit like this. Input or output?

Steen😎
Click to expand...

Steen,

I will say it again, your work is one of the best around. Absolutely very nice boards you did. Which etching solution are you using? Hope to do some as nice as yours, some day.:xeye:

Regarding the pot position it’s a matter of preference and testing, but will also depend on your source output impedance. If you plan to use it with a highish source impedance I would try it at the output of the preamp. But otherwise I would put it at the front, guess that the original NS10 was also at the input.

For the front pot try a 20K and for the rear position I would start with a 10K and increase it to 20K if you think it’s to much load.🙂
 
#132
Thanks Russ for all the effort, think all is coming out nice😎

Next board iteration, after ironing other issues and of course after some testing results I would suggest you try to put all 3 transistors closer still, the closer you can. I think it would be well worth the effort.🙂
 
#134
PSU

Russ,

I think a good PSU for this pre would be what you have on the XBOSOZ. If you agree pls post the schematic for others to see.

For all of you:
Rails after regulation would be +25/-25V, so adjust zeners to have these voltages (some 28V zener stacks).

It would be a good idea to load the outputs of the regulators with some 10mA using a shunt resistor to get good voltage stability. This means to add a 2.5K resistor from rail to ground after the PSU output caps.
 
#139
Re: PSU

apassgear said:
Russ,

I think a good PSU for this pre would be what you have on the XBOSOZ. If you agree pls post the schematic for others to see.

For all of you:
Rails after regulation would be +25/-25V, so adjust zeners to have these voltages (some 28V zener stacks).

It would be a good idea to load the outputs of the regulators with some 10mA using a shunt resistor to get good voltage stability. This means to add a 2.5K resistor from rail to ground after the PSU output caps.
Click to expand...


shunt current-make it 30 or 50 mA
piece of cake with this voltage and used (proposed) parts
3w resistor per rail will do the job
 
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