need a good low parts phono tube preamp schematic.... - 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 3rd December 2004, 03:44 AM   #1
diyAudio Member
 
Join Date: Nov 2004
Location: Edmonton
Default need a good low parts phono tube preamp schematic....

gotta make a christmas present there for my electronics mentor figured since he's got boxes and boxes of vinyl (around 5000) i'd finally make him a preamp, anyone got any good designs? i've got about 2 or 3 matched pairs of 12au7's i'd like to use up, i've looked on the net and am having trouble finding much..
  Reply With Quote
Old 3rd December 2004, 04:05 AM   #2
Enzo is offline Enzo  United States
diyAudio Member
 
Join Date: Sep 2004
Location: Lansing, Michigan
Look in the back of the RCA tube manual. One of the sample circuits is a tube phono preamp with RIAA curve. it is based on one 7025. (12AX7) I would think the 12AU7 was a bit low gain for the application. Very simple circuit. You would need one per channel. SO two 12AX7 and a handful of small parts. You also need power supply.

You could probably make something with one 12AX7, but I don't see how you could get RIAA that way.
  Reply With Quote
Old 3rd December 2004, 01:02 PM   #3
GeirW is offline GeirW  Norway
diyAudio Member
 
GeirW's Avatar
 
Join Date: Jan 2004
Location: Trondheim, Norway
Gday.

Look at bonavolta page:
http://www.bonavolta.ch/hobby/en/aud...el.htm#Various


  Reply With Quote
Old 3rd December 2004, 01:37 PM   #4
RIP
 
pedroskova's Avatar
 
Join Date: Dec 2002
Location: C'ville VA, USA
not exactly "low parts count" but worth it...
  Reply With Quote
Old 3rd December 2004, 03:17 PM   #5
GeirW is offline GeirW  Norway
diyAudio Member
 
GeirW's Avatar
 
Join Date: Jan 2004
Location: Trondheim, Norway
Gday.

Ohashi looks interesting,
with 3x12AX7/ECC83 and 12. res/log , 4. cap`s
it`s "low part". Haven`t a clue about the sound,
but i assume minimal use of passive components
can speak for quality. It shouldn`t sound worse than AR SP3
i reckon. Have you looked at the phono stage of the
Audio Innovation 500.




Attached Images
File Type: png ai500phono.png (5.3 KB, 3701 views)
  Reply With Quote
Old 3rd December 2004, 03:59 PM   #6
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Default Re: need a good low parts phono tube preamp schematic....

Konnichiwa,

Quote:
Originally posted by Rockmonton
gotta make a christmas present there for my electronics mentor figured since he's got boxes and boxes of vinyl (around 5000) i'd finally make him a preamp, anyone got any good designs? i've got about 2 or 3 matched pairs of 12au7's i'd like to use up, i've looked on the net and am having trouble finding much..
Well, the 12AU7 is not particulary useful in a Phonostage.

If you can scrounge up a single ECC83/12AX7 and a single ECC88/E88CC/6922 you could build the Phonostage I described here:

http://www.diyaudio.com/forums/showt...624#post335624

The thread following on has a lot of discussion on this, suitable PSU, implementation etc....

Sayonara
  Reply With Quote
Old 3rd December 2004, 06:11 PM   #7
diyAudio Member
 
Geek's Avatar
 
Join Date: Sep 2004
Here's an active EQ phono stage from one of my more sucessful designs
Attached Images
File Type: png phono-stage.png (7.0 KB, 3581 views)
  Reply With Quote
Old 4th December 2004, 06:55 AM   #8
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by Enzo
Look in the back of the RCA tube manual. One of the sample circuits is a tube phono preamp with RIAA curve
It lacks the undocumented time-constant, but here it is

From the 1966 RCA Receiving Tube Manual.

dave
Attached Images
File Type: gif rca-riaa-phono.gif (55.3 KB, 3519 views)
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 5th April 2005, 12:27 AM   #9
diyAudio Member
 
gmilitano's Avatar
 
Join Date: Apr 2004
Location: Winnipeg, Manitoba
Quote:
Originally posted by planet10


It lacks the undocumented time-constant, but here it is

From the 1966 RCA Receiving Tube Manual.

dave

Are 12AX7 close enough to a 7025 for use with this schema? If not, is there an RIAA schematic for 12AX7? I'd be looking for a simple design, one 12AX7 per channel, no output transformer and about 30-40dB gain (for MM phono).

Any leads or info is always appreciated.
Gio.
  Reply With Quote
Old 5th April 2005, 12:33 AM   #10
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Quote:
Originally posted by GG
Are 12AX7 close enough to a 7025 for use with this schema? If not, is there an RIAA schematic for 12AX7? I'd be looking for a simple design, one 12AX7 per channel, no output transformer and about 30-40dB gain (for MM phono).
A 7025 is a 12AX7 -- supposedly selected for higher performance, but in practise the variations are such that it is a no care.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  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
Good Phono preamp circuit? PeterMoreton Solid State 45 30th November 2011 11:49 AM
Tube Phono Preamp PCB Ebay? are these any good fortytwo Tubes / Valves 12 7th July 2009 01:47 AM
DIY tube phono preamp ? abacus Analog Line Level 2 16th September 2008 11:08 PM
Question about phono preamp schematic jn2630 Tubes / Valves 11 3rd January 2008 01:36 AM
phono tube preamp? karma Tubes / Valves 7 4th July 2003 01:19 PM


New To Site? Need Help?

All times are GMT. The time now is 11:18 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