Lowering gain in 12AX7 SRPP preamp - Page 3

Asen · 22nd December 2003, 10:10 AM

You can find more info about my DIY project here:

Tube pre-amp

JBasham · 22nd December 2003, 09:14 PM

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."

Asen · 22nd December 2003, 10:50 PM

OK, I took a picture for you...

fdegrove · 23rd December 2003, 12:18 AM

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?

Cheers,

ALBQ · 23rd December 2003, 02:19 AM

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

Asen · 23rd December 2003, 01:24 PM

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

Asen · 23rd December 2003, 05:55 PM

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.

22nd December 2003, 09:14 PM	#22
JBasham diyAudio Member Join Date: Apr 2003 Location: At Home	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." __________________ The only true thing in audio is what you hear with your own ears.

23rd December 2003, 12:18 AM	#24
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	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? Cheers, __________________ Frank

23rd December 2003, 02:19 AM	#25
ALBQ diyAudio Member Join Date: Dec 2003 Location: Albuquerque	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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22nd December 2003, 10:10 AM	#21
Asen diyAudio Member Join Date: Jan 2001 Location: Sofia	You can find more info about my DIY project here: Tube pre-amp

23rd December 2003, 01:24 PM	#26
Asen diyAudio Member Join Date: Jan 2001 Location: Sofia	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

23rd December 2003, 05:55 PM	#27
Asen diyAudio Member Join Date: Jan 2001 Location: Sofia	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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