Valve Itch phono - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

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 25th May 2010, 01:21 AM   #11
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by RCruz View Post
I Salas

Is there a thread on the bench ?
Kofi Annan in: "Cascodin' with Steve Bench's RIAA!"
  Reply With Quote
Old 25th May 2010, 01:58 AM   #12
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I like that low impedance RIAA. I was never comfortable with very high impedance circuits.
Why do you not use a cathode resistor at the input ? Noise ? Some lokal degeneration could improve TDH. Some second harmonic can sound very attractive though. I learned that when i build the PSG buffer. Another option whould be to put the transformer in the cathode.
  Reply With Quote
Old 25th May 2010, 09:11 AM   #13
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Yes, noise. Interestingly after a year I made it, I read Vogel's silence and he is pointing out the SRPP & mu topologies and no grid resistor as best for noise. He he, nice. I would think about just an IR LED the most on cathode. The THD probably comes from driving the 22K from the high rp follower upper section though... Paralleling 2 sections up & down the mu would do better for noise and drive, those 6N2PEV are not costly. A tube like E810F trioded or D3A would be best noise wise. I just had the Russians and tested. I got surprised by the non existent microphony from those.

6N2P
  Reply With Quote
Old 25th May 2010, 11:36 AM   #14
R.I.P.
 
Join Date: Dec 2001
Location: Schaffhausen Switzerland
[QUOTE=Salas;2197581]Those 1.4 & 4mA on the schematic are actually measured as far as I recall but could have made a typo as well. /QUOTE]

Doesn't make sense to me.

You have the first tube without any cathode R, yet get 1.4mA. The second tube has substantial cathode bias yet you get three times as much current at 4mA. And in both cases the bias R on the upper tube is the same.

???????

Regards, Allen
  Reply With Quote
Old 25th May 2010, 11:45 AM   #15
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Don't remember, really. I have to get it back or visit the friend I gave it to and see again the drop on 1st stage RC filter's 3k3 inline with PSU. Maybe I mixed something back then and noted those numbers. Second tube is different, its 6H8/6SN7.
  Reply With Quote
Old 25th May 2010, 11:52 AM   #16
cjcc67 is offline cjcc67  Australia
diyAudio Member
 
Join Date: Aug 2009
Location: Melbourne
Salas,
i now have three itch!! 1.simple pre pre 2 simple riaa, 3 Allens FVP5 and this one!! Better get scratchin'!!
  Reply With Quote
Old 25th May 2010, 11:54 AM   #17
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
  Reply With Quote
Old 25th May 2010, 03:49 PM   #18
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Got intrigued and since I haven't got it in hand to measure the first stage current, I made a simulation on LT Spice. I used a 12AX7 model which is not far from 6N2 just to be in the ballpark. It roughly follows that 1.4 mA first stage schematic note.
Attached Images
File Type: gif uBias.gif (10.3 KB, 1559 views)
  Reply With Quote
Old 16th September 2010, 06:01 AM   #19
diyAudio Member
 
Dogie_Hogan's Avatar
 
Join Date: Jul 2005
Location: Tube Town
All octal tubes: the 6SL7 in stead of the 6N2P?

Last edited by Dogie_Hogan; 16th September 2010 at 06:05 AM.
  Reply With Quote
Old 27th September 2010, 03:00 AM   #20
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Sorry for the late reply. Haven't tried anything different there. The first stage is based enough on the characteristics of the cheap Russian tube though. If you want to make an experiment with 6SL7 you are welcome.
  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
Got the build itch again. 80w kt88 itsmejto Tubes / Valves 44 26th September 2008 11:49 PM
valve phono stage wanted for mc brobarrie Swap Meet 1 13th August 2007 08:17 PM
Basic DIY Valve Phono Stage matthew2456 Tubes / Valves 5 29th March 2007 04:11 AM
Phono pre, valve or jfet lndm Analogue Source 7 4th April 2006 02:11 PM
phono preamp design for c3m postie valve fergs1 Tubes / Valves 1 29th May 2005 02:12 PM


New To Site? Need Help?

All times are GMT. The time now is 06:00 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