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Old 12th October 2012, 02:06 PM   #1171
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Quote:
Originally Posted by Tolu View Post
Nice idea with the little TL431 PCB! Does it work as you planned?
Yes, work as planned , with a distortion analyzer (Or a pc with a fft program) I can tune for the lowest distortion (0,5V can be the difference between 0,7% or 0,05%)



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@tinitus: the chinese are copying anything. Not innovative but cheap.
Actually is a copy of Manu's board

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Old 12th October 2012, 02:25 PM   #1172
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Quote:
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@tinitus: the chinese are copying anything. Not innovative but cheap.
well, now you mention it, ripping off schematics that way, fast and easy, and you see what happens
but it sticks and could have ill effects, and be like poison poluting the forum
but no worry, you are not being blamed, not your problem
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Old 14th October 2012, 11:23 AM   #1173
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After reading the post from Tschrama with the table of Idss and voltage I have seen that my 2SK170 that I've got from a group buy have 4.9 mA so I can expect a THD of about 2% at around 8V.

I think it would be better to get new ones that have an Idss of about >8 mA! Anyone who can sell 4 or 8 pieces of them?

Last edited by Tolu; 14th October 2012 at 11:27 AM.
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Old 3rd December 2012, 03:03 PM   #1174
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Default Asking Too Much

I'm asking too much out of my BOZ-J. With 16v supply, it's driving a MOX II and F5 and SIT 5w amp.

I don't really want a new preamp right now. I like the BOZ-J and what it can do. I'd like to increase the power supply without increasing distortion, and further still, keep it in the "sweet spot".

I don't have a distortion analyzer, so anyone who has build a BOZ-J with a higher supply, what have you found to be a good setting of votage and current?

Thanks,

Vince
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Old 3rd December 2012, 08:47 PM   #1175
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I run mine on 27V with no problems. I like the sound too but lately have found a 6N7 tube based preamp I just finished to have better bass and sound stage. But as a dead simple low distortion preamp they can't be beat.
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Old 3rd December 2012, 08:59 PM   #1176
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Thanks mhouston. What did you use on the source resistor?
Currently using 22 ohm with 16v.

Thanks,

Vince
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Old 3rd December 2012, 09:17 PM   #1177
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Thanks mhouston. What did you use on the source resistor?
Currently using 22 ohm with 16v.

Thanks,

Vince
I left the cct. as is.
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Old 4th December 2012, 03:31 AM   #1178
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Was able to get the voltage up to 26v by changing 1 resistor on the LM317 regulator.
sounds nice!
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Old 11th December 2012, 09:13 AM   #1179
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Can anyone post the voltage that is needed to drive my 2SK170s with 4.9mA Idss to lowest distortion? I don't have any measurement equipment for this and my ears are too old and used to decide it by sound.
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Old 11th December 2012, 09:47 AM   #1180
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Quote:
Originally Posted by Tolu View Post
Can anyone post the voltage that is needed to drive my 2SK170s with 4.9mA Idss to lowest distortion? I don't have any measurement equipment for this and my ears are too old and used to decide it by sound.
With a pc, a sound card and a fft program you can measure the distortion.

Looking For: Basic Dumb FREE FFT measurement Software??

Just with a sinus tone at the preamp input (for example 1 kHz) and the preamp output connected to "line in" of the sound card, you can see the tone and his harmonics. You need just move the value of the voltage supply for get the lowest harmonic amount
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