Circuit indentification - 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 1st August 2007, 05:47 AM   #1
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
Default Circuit indentification

Guys, what this 6DJ8 circuit called, and is there somewhere that explains how it works and how good/bad it is, it drives (C14 .47uf)a 10megohm video buffer called a BUF03, I lowered the 10meg input resistor to 510k as it was flapping the woofer a bit at <1hz

Cheers George
Attached Images
File Type: jpg cci00116x.jpg (91.8 KB, 333 views)
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  Reply With Quote
Old 1st August 2007, 02:25 PM   #2
oshifis is offline oshifis  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
I don't know the name, but it is a high-input impedance FET gain stage driving a common-grid tube stage. This configuration has high gain with very high bandwidth due to the low Miller capacitance of the tube.
  Reply With Quote
Old 1st August 2007, 02:47 PM   #3
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Looks like a variation on a cascode to me....

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
Old 1st August 2007, 03:50 PM   #4
KaDe is offline KaDe  Germany
diyAudio Member
 
KaDe's Avatar
 
Join Date: May 2007
George,

that cascode-stage should work fine as phono input.
Very low noise and high gain.
I use a similar in one of my phono-preamps with good results.
The FET is sonicaly invisible.
What´s your application to it ?

Klaus
  Reply With Quote
Old 1st August 2007, 04:04 PM   #5
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally posted by planet10
Looks like a variation on a cascode to me....

dave
Not even a variation, it's a plain old cascode.

Its potential bandwidth can only be realized if its output loading is very light- output impedance is roughly equal to the plate load resistor. A BUF03 is welcome there.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 1st August 2007, 04:43 PM   #6
diyAudio Member
 
Join Date: Oct 2001
Location: .
Quote:
Originally posted by KaDe

What´s your application to it ?

Klaus

A Counterpoint SAx000 ?
  Reply With Quote
Old 1st August 2007, 05:12 PM   #7
KaDe is offline KaDe  Germany
diyAudio Member
 
KaDe's Avatar
 
Join Date: May 2007
Yes,

Counterpoint SA-9 Phono and the SA-11 Control amps from 1990
had this gain-stages also.

- some full house equipment btw -
  Reply With Quote
Old 1st August 2007, 05:26 PM   #8
diyAudio Member
 
Join Date: Oct 2001
Location: .
Quote:
Originally posted by KaDe
Yes,

Counterpoint SA-9 Phono and the SA-11 Control amps from 1990
had this gain-stages also.

- some full house equipment btw -

Thought they were all glass, mostly octal, right down to the psu.
  Reply With Quote
Old 1st August 2007, 06:17 PM   #9
KaDe is offline KaDe  Germany
diyAudio Member
 
KaDe's Avatar
 
Join Date: May 2007
Here is a scan from an old magazin with the Conuterpoint SA-9 Phono case.
Most of the glass is working in the psu at the back side.
In the front four 6DJ8 with solid state assistance.
Attached Images
File Type: jpg counterpoint-sa-9.jpg (95.8 KB, 158 views)
  Reply With Quote
Old 1st August 2007, 08:28 PM   #10
diyAudio Member
 
georgehifi's Avatar
 
Join Date: Sep 2003
Location: Manly Australia (Jewel of the Pacific)
Send a message via MSN to georgehifi
RFBRW get's the cigar for "id"ing first, yes it's a Counterpoint SA3000 that I snaffled. it actually has six in total BUF03's, 4 x in the phono section along with 2 x 6922's and two on the output along with 2 x 6922's.
I haven't tried the phono but the line stage sounds superb very powerful transparent tight and smooth. This is one of the best tube sounds I have heard.
I lowered the input resistor from 10meg to 680k because of wandering subsonic dc getting through the .47 cap , SY seems to think that maybe the bandwidth has been compromised now that I've lowered it to 680k. It was flat out to 300khz before, but I didn't check it after the resistor change. Still sounds like it's going very high in frequency.

Cheers George
Attached Images
File Type: jpg e3b4_3xxxx.jpg (96.2 KB, 119 views)
__________________
Avatar : Production Lightspeed Attenuator
www.lightspeedattenuator.com
  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
Need help on EQ circuit Buzzy Parts 3 25th September 2007 02:52 PM
Help finding TS parameter/driver indentification please (pics) > beady Multi-Way 2 1st August 2005 09:41 AM
Trouble with speaker protection circuit (Randy Slone's circuit) whalefat Solid State 3 13th April 2005 10:13 AM
Zener diode indentification! bbakota2000 Parts 2 22nd March 2004 11:55 PM
Help with a circuit Petman Tubes / Valves 9 6th February 2003 01:51 PM


New To Site? Need Help?

All times are GMT. The time now is 07:23 AM.


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