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Old 22nd December 2003, 10:10 AM   #21
Asen is offline Asen  Bulgaria
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You can find more info about my DIY project here:

Tube pre-amp
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Old 22nd December 2003, 09:14 PM   #22
JBasham is offline JBasham  United States
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Have you tried using a 5751 instead of a 12AX7?

It's usually a drop-in substitute and it has less gain.

Also many of my friends and I prefer the sound of the 5751 to the sound of the 12AX7. It ususally sounds less "fuzzy" or "muddy."
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Old 22nd December 2003, 10:50 PM   #23
Asen is offline Asen  Bulgaria
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OK, I took a picture for you...
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File Type: jpg srpp in.jpg (81.7 KB, 483 views)
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Old 23rd December 2003, 12:18 AM   #24
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Hi,

Looks nice, Asen.

Instead of using the resistive voltage divider at the input you could try some degenerative feedback by removing the decoupling cap across the cathode resistor if Zo is not crucial.

Also, why do you have a 1M and 47K R in // at the output?

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Old 23rd December 2003, 02:19 AM   #25
ALBQ is offline ALBQ  United States
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Default 12AX7 Pictures

Asen,
Very Nice - also, good job on the internal wiring. Thank you for for taking time to post the pictures. I will need to get a few pictures off on my latest preamp project as it progresses. Thank you and nice work.
ALBQ

FYI - link to my webpage - need updating with latest projects
http://mywebpages.comcast.net/gilles...-MainPage.html
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Old 23rd December 2003, 01:24 PM   #26
Asen is offline Asen  Bulgaria
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Thank you all for the comments!

fdegrove,

I tried it without cathode caps but I didn't like the results. Also I don't think the input voltage divider is quite a problem. It is the same thing to have a 250k pot and to turn the volume just a little. The resistor gives me more possibilities to play around with the volume control.

Regards
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Old 23rd December 2003, 05:55 PM   #27
Asen is offline Asen  Bulgaria
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The 47k at the output is just a load resistor I put for simulation purposes. It doesn't exist in reality. There's 1M resistor only.

ALBQ, nice webpage. Your amps look impresive.
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