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 20th April 2013, 12:13 PM   #1981
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
Quote:
Originally Posted by Salas View Post
Maybe bins too little. Here's what I got. Noise floor no test tone, response, 1kHz test tone.

edit: Now the correct files FFT
Hey Nick, did you make a note of what the preamp output voltage was for the last image?
  Reply With Quote
Old 20th April 2013, 12:25 PM   #1982
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
About 300mVRMS not to push the audio card.
  Reply With Quote
Old 20th April 2013, 12:27 PM   #1983
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
Quote:
Originally Posted by buzzforb View Post
First pic is loopback showing baseline at output level to measure 1W performance of amp. I have some 60hz niose, but it was do to crappy test rig.

As for 6V6, RCA blackplates is my choice as well. New Tungsol was very good( have matched quad for diff version), but Military grade RCA was worth money and this amp is worth the upgrade.
Its a beauty Mr Aldrin
  Reply With Quote
Old 20th April 2013, 12:34 PM   #1984
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by flatheadmurre View Post
LM317 works fine just adjust the current down until you get best performance.

I donīt remember exactly what i ended up with but itīs a bit lower then Salas original setup.
Depends on tubes brand and vintage also. CCSing for about 6.1V Vh is OK.
  Reply With Quote
Old 21st April 2013, 08:07 AM   #1985
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
Hi

I made me a filament CSS and tried some different resistorvalues and I can confirm that tube brands/age etc varies a lot in the filaments, I get values between 5,6-6,4 volts just by testing a handfull.

Seems like I need a VR pot in parallel to adjust. Maybe 3,3/18/VR100 or something.

Whats the deal on going for current adjust and why not a voltage one?
  Reply With Quote
Old 21st April 2013, 08:29 AM   #1986
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
One thing is it lends soft start, the other thing is many find it subjectively preferable. Listen 4 your self and tell us your unbiased opinion.
  Reply With Quote
Old 21st April 2013, 08:33 AM   #1987
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
Yes it soft starts. I will rig it in with 2 tubes that goes slightly under 6,3 with a 3,3/18 in parallell.

If going with CSS it seems like I have first match the fixed resistors closely with DMM and then to make it adjustable
  Reply With Quote
Old 21st April 2013, 08:53 AM   #1988
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
45sec to 1min with 6V6 to fully come up if I remember well. Yes, better have a means of slightly adjusting when having a stash of various makes and ages. Also to explore some starving sweet spot if you can feel any differences as Flathead does.
  Reply With Quote
Old 21st April 2013, 09:18 AM   #1989
stajo is offline stajo  Sweden
diyAudio Member
 
Join Date: Jun 2011
Location: Stockholm
It was impossible to tell since I still have this 100 Hz hum from hell that I dont seem to stumble over any solution to.

When I plug poweramp and pre in it starts with a gigantic hum that almost goes away when the 6V6es heats up and biases. But just almost.

The hum has some variations in character depending on how I feed the filaments. AC, DC, CSS, Voltage regulator, groundreferenced, lifted etc. But theres always a hum.

Maybe I'll throw the towel for now
  Reply With Quote
Old 21st April 2013, 09:51 AM   #1990
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Did you ground them heaters on a grounded chassis to psu return?
  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
Help me design my DAC/Line Preamp. kuroguy Tubes / Valves 7 2nd April 2009 08:31 PM
preamp line ctt richwalters Tubes / Valves 1 7th March 2008 04:34 PM
Preamp for Line In and Mic blur Instruments and Amps 1 4th January 2007 04:02 PM
Line stage preamp, based on SY's "Heretical Unity gain line stage" Danko Tubes / Valves 23 18th July 2005 04:07 AM
Line preamp for 2A3 amp Petman Tubes / Valves 0 24th May 2002 03:11 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 Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2