12ax7 preamp,need help.

digi01 · 8th April 2004, 08:51 AM

I have a couple of 12AX7LPS tubes, plan make a preamp.have what propose?

analog_sa · 8th April 2004, 11:55 AM

Get different tubes.

Frank Berry · 8th April 2004, 12:02 PM

What type of preamp? Phono or a basic system control preamp.

analog_sa · 8th April 2004, 03:39 PM

These days when people say preamp they mean line stage. The 12AX7 is probably suitable for phono duties but quite pointless in a line stage.

digi01 · 9th April 2004, 03:17 AM

thanks for reply

I plan to make a line stage,A lot of friends around me say that 12AX7LPS are adjusted very badly,but the sound is very fine,very warm.

This is my sch,any suggestions?

fdegrove · 9th April 2004, 04:08 AM

Hi,

The cap after the 6X4 is really high, about 10µF should be a lot safer.

Cheers,

digi01 · 9th April 2004, 04:17 AM

sure,thank you.

-digi

cogsncogs · 9th April 2004, 04:45 AM

Quote:

The cap after the 6X4 is really high, about 10µF should be a lot safer.

Yes definitely change that cap. Should sound nice and warm and fuzzy!

Enjoy!
Wayne

Alastair E · 9th April 2004, 11:04 AM

Personally, I would go for the 6SN7gt, or the 6SL7gt if you need that extra gain, the 12ax7 aint a great valve, a bit prone to microphonics, Changed dosens of them over the years!

The 6sn7/6sl7 have a great reputation it seems, but they are an International Octal 8 pin, and benefit from DC heaters to reduce injected hum, especially in phono stages!

isak0411 · 11th April 2004, 01:56 AM

Quote:

Originally posted by Alastair E
Personally, I would go for the 6SN7gt, or the 6SL7gt if you need that extra gain, the 12ax7 aint a great valve, a bit prone to microphonics, Changed dosens of them over the years!

The 6sn7/6sl7 have a great reputation it seems, but they are an International Octal 8 pin, and benefit from DC heaters to reduce injected hum, especially in phono stages!

Hi, alastair
can i use 6sn7 for phono stage & 12ax7 for line stage?

isak0411

8th April 2004, 08:51 AM	#1
digi01 diyAudio Member Join Date: Mar 2003 Location: BEIJING	12ax7 preamp,need help. I have a couple of 12AX7LPS tubes, plan make a preamp.have what propose? __________________ 2010 DIY ALBUM UPDATED UCPv1(preamp) & DUAL(power supply)

8th April 2004, 12:02 PM	#3
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	What type of preamp? Phono or a basic system control preamp. __________________ Frank

9th April 2004, 04:08 AM	#6
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, The cap after the 6X4 is really high, about 10µF should be a lot safer. Cheers, __________________ Frank

9th April 2004, 04:17 AM	#7
digi01 diyAudio Member Join Date: Mar 2003 Location: BEIJING	sure,thank you. -digi __________________ 2010 DIY ALBUM UPDATED UCPv1(preamp) & DUAL(power supply)

9th April 2004, 11:04 AM	#9
Alastair E diyAudio Member Join Date: Feb 2004 Location: South Wales	12ax7 Personally, I would go for the 6SN7gt, or the 6SL7gt if you need that extra gain, the 12ax7 aint a great valve, a bit prone to microphonics, Changed dosens of them over the years! The 6sn7/6sl7 have a great reputation it seems, but they are an International Octal 8 pin, and benefit from DC heaters to reduce injected hum, especially in phono stages! __________________ Das Beste Oder Nichts

8th April 2004, 11:55 AM	#2
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	Get different tubes.

8th April 2004, 03:39 PM	#4
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	These days when people say preamp they mean line stage. The 12AX7 is probably suitable for phono duties but quite pointless in a line stage.

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