12ax7 preamp. - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 10th September 2008, 04:20 PM   #1
diyAudio Member
 
Join Date: Mar 2008
Default 12ax7 preamp.

Hi, everyone.,
I have 2 pcs of jj 12ax7, and want to DIY a preamp . . can someone recommend me a schematics? many thanks
  Reply With Quote
Old 10th September 2008, 05:27 PM   #2
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Can you be more specific? Line stage or phono pre-amplifier? The 12AX7A would not be near the top of my list as a choice today for a line stage, although all of my older line stage designs used them and sounded quite good.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 10th September 2008, 06:00 PM   #3
domjun is offline domjun  Indonesia
diyAudio Member
 
Join Date: Jun 2007
I just wonder what exactly in the top of your list for line stage preamp.
Is it one of these tubes: 6N30P or 6NP or 12BH7A?

Thanks for your opinion.
  Reply With Quote
Old 10th September 2008, 06:24 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Quote:
Originally posted by domjun
I just wonder what exactly in the top of your list for line stage preamp.
Is it one of these tubes: 6N30P or 6NP or 12BH7A?

Thanks for your opinion.

Nope, My current faves are all dhts 01, 12, and 26 not necessarily in that order. I would also include the 6SN7 and 6J5 in my "second tier." And I use transformers...
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 10th September 2008, 06:36 PM   #5
diyAudio Member
 
Join Date: Jun 2004
Location: Indiana
I don't usually look for opportunities to use GNF but this might be an instance where it would be appropriate. If we are talking line preamp why not a standard CC stage direct coupled to CF with global negative feedback from the output of the CF back to the CC stage to control the excessive gain of the 12AX7.
__________________
If We The People refuse to hear the truth we will be ruled by liars.
  Reply With Quote
Old 10th September 2008, 07:29 PM   #6
diyAudio Member
 
Join Date: Mar 2008
great Thanks for your reply Kevinkr, I need it just for my bookshelf speaker I made in 6.5". I only have CD player... what do you suggest? thanks again
  Reply With Quote
Old 10th September 2008, 07:39 PM   #7
diyAudio Member
 
MQracing's Avatar
 
Join Date: Oct 2005
check out the following url

http://www.shine7.com/audio/12ax7_pre.htm
  Reply With Quote
Old 10th September 2008, 08:35 PM   #8
diyAudio Member
 
jerluwoo's Avatar
 
Join Date: Feb 2006
Location: Ashland,Ky U.S
Mashaffer's suggestion is a good place to start. The problem with the 12ax7 is lack of drive current. Don't expect it to drive anything below 40k input impendence very well. Attached is a good starting schematic thats pretty simple to build.
Attached Images
File Type: gif 12ax7.gif (18.9 KB, 802 views)
  Reply With Quote
Old 10th September 2008, 09:25 PM   #9
domjun is offline domjun  Indonesia
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally posted by kevinkr



Nope, My current faves are all dhts 01, 12, and 26 not necessarily in that order. I would also include the 6SN7 and 6J5 in my "second tier." And I use transformers...

Of course you're right.
I have received a pair of 26 from Netherland. Hope I could make them sings in the near time

But the first try would be without transformers
  Reply With Quote
Old 11th September 2008, 12:15 AM   #10
diyAudio Member
 
Join Date: Mar 2008
many thanks to everyone above. ... . another thing is a PT. , what is the minimum specs (requirements) for this 12ax7 preamp. .. voltage and DC current. . .... thanks again...
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for a Balanced Mic Preamp w 12AX7 Ahmad_tbp Tubes / Valves 6 7th September 2012 11:37 AM
2x 12AX7 preamp fuse value gottlieb Tubes / Valves 7 18th May 2009 03:29 AM
12AX7 preamp project Mrpong Tubes / Valves 0 24th January 2006 11:47 AM
12ax7 preamp Antonix Tubes / Valves 4 17th November 2005 02:52 PM
12ax7 preamp,need help. digi01 Tubes / Valves 13 12th April 2004 07:00 AM


New To Site? Need Help?

All times are GMT. The time now is 04:58 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2