Go Back   Home > Forums > >

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

6V6 line preamp
6V6 line preamp
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
Old 24th November 2020, 10:32 PM   #3721
Anchan is offline Anchan  United States
diyAudio Member
 
Join Date: Jul 2009
Popped in these metal can 6V6's for gain mode.
I wondered if they would be less microphonic- not really actually.
The hum and noise I think are a little less than the Tung Sol reissues.
More than anything the noise is just.... different.
They sound pretty good overall though! They definitely get hot and look tough!
Attached Images
File Type: jpg metal.jpg (260.2 KB, 272 views)
  Reply With Quote
Old 25th November 2020, 01:59 AM   #3722
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
6V6 line preamp
They compliment this chassis looks. You grounded the metal bottles through pin one I presume.
  Reply With Quote
Old 25th November 2020, 03:09 AM   #3723
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
6V6 line preamp
I wonder, would 7.5dB gain be enough for you? In other words two and a half times lower than you now got. That change can be implemented with a negative feedback network. Add 120K in series between the input (after the pot) and the 1K grid stopper. From their node connect a 560K resistor to the stage's output (after the output capacitor). Microphony will go down, noise will go down, THD will go down. Easy to do, evaluate and decide.
Don't use a higher than 50K volume pot with this arrangement. Matter of the pot's output impedance interfacing. Otherwise let me know to give you alternative values if you use a 100K pot or in case you want a different gain.
  Reply With Quote
Old 25th November 2020, 06:10 PM   #3724
Anchan is offline Anchan  United States
diyAudio Member
 
Join Date: Jul 2009
Yup, grounded pin 1 via nearby chassis screw and short wire.

Thanks for this suggestion. I'm going to save this post for later because I'd like to implement it at some point. I really like the idea.

Right now I do need the gain, because I'm using it a lot as a headphone amp and it's just the right amount of gain. And in phones, it's dead silent all around.

And to be fair, running the gain stage into my current amp with 27dB of gain is not quite fair. But once I get my other amp complete that has 12db gain, 7.5dB gain might be just fine.

I'm going to implement the DC heaters solution at some point too. Yesterday while I had it open, I disconnected the CT from gnd on the heater windings, and connected it to the top of the cathode resistor. That point is only +14V, so maybe not optimal, but it did reduce the hum a bit, but for some reason the tube became more microphonic- weird! So connected back to gnd. Maybe DC heaters will be the final refinement.

So I'll keep everything as it is for now, and just sit back and enjoy. CF into amp sounds killer, and I've never enjoyed headphones this much.



Quote:
Originally Posted by Salas View Post
I wonder, would 7.5dB gain be enough for you? In other words two and a half times lower than you now got. That change can be implemented with a negative feedback network. Add 120K in series between the input (after the pot) and the 1K grid stopper. From their node connect a 560K resistor to the stage's output (after the output capacitor). Microphony will go down, noise will go down, THD will go down. Easy to do, evaluate and decide.
Don't use a higher than 50K volume pot with this arrangement. Matter of the pot's output impedance interfacing. Otherwise let me know to give you alternative values if you use a 100K pot or in case you want a different gain.
  Reply With Quote
Old 26th November 2020, 12:23 AM   #3725
egellings is offline egellings  United States
diyAudio Member
 
Join Date: Aug 2010
Location: CA
6V6 will work for a line amp quite well. My question is, why such a big tube for such a small signal?
  Reply With Quote
Old 26th November 2020, 02:34 AM   #3726
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
6V6 line preamp
Its storied early in the thread, I was trying to find a poor man's DHT type of big sound without the difficulty, rarity, and expense of making a true DHT preamp. This indirectly heated beam tetrode when forced to triode was sounding to me like it kinda fitted the bill. I succeeded in as big and microphonic as a true DHT at least.
  Reply With Quote
Old 26th November 2020, 03:22 AM   #3727
6L6 is offline 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
6V6 line preamp
The output can be taken directly off the plate with suitably low Z. Single stage amplification. It has a beautiful quality.
  Reply With Quote
Old 26th November 2020, 01:05 PM   #3728
kodabmx is offline kodabmx  Canada
Spreading triode love.
diyAudio Member
 
kodabmx's Avatar
 
Join Date: Oct 2011
Location: Toronto
6V6 line preamp
And the 6P1P is like $1...
__________________
If you can't learn to do something well, learn how to enjoy doing it poorly.
  Reply With Quote
Old 27th November 2020, 09:53 AM   #3729
Bas Horneman is offline Bas Horneman  Netherlands
diyAudio Moderator Emeritus
 
Bas Horneman's Avatar
 
Join Date: Apr 2002
Location: The Netherlands
Quote:
6V6 will work for a line amp quite well. My question is, why such a big tube for such a small signal?
As diy builders we luckily don't have to ask ourselves this question. Picture is DHTROB's 845 preamplifier
Attached Images
File Type: jpeg IMG_0582.jpeg (315.2 KB, 173 views)
__________________
http://basaudio.wordpress.com
  Reply With Quote
Old 27th November 2020, 03:49 PM   #3730
Monk55 is offline Monk55  United States
diyAudio Member
 
Join Date: Jul 2011
Location: Seattle
6V6 line preamp
Quote:
Originally Posted by Bas Horneman View Post
As diy builders we luckily don't have to ask ourselves this question. Picture is DHTROB's 845 preamplifier
Coool
__________________
The simpler you can make an amplifier, the more likely there is a good correspondence between the sonic performance and what you measure on a bench. N.Pass
  Reply With Quote

Reply


6V6 line preampHide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Help me design my DAC/Line Preamp. kuroguy Tubes / Valves 7 2nd April 2009 09:31 PM
preamp line ctt richwalters Tubes / Valves 1 7th March 2008 05:34 PM
Preamp for Line In and Mic blur Instruments and Amps 1 4th January 2007 05:02 PM
Line stage preamp, based on SY's "Heretical Unity gain line stage" Danko Tubes / Valves 23 18th July 2005 05:07 AM
Line preamp for 2A3 amp Petman Tubes / Valves 0 24th May 2002 04:11 PM


New To Site? Need Help?

All times are GMT. The time now is 08:04 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki