Tone circuit and other guitar amp Q's - 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 December 2006, 11:00 PM   #1
PRNDL is offline PRNDL  United States
diyAudio Member
 
Join Date: Oct 2006
Default Tone circuit and other guitar amp Q's

I am copying a guitar amp and have some questions.
It's an EL84 push-pull amp - about 18 watts, with a circuit very similar to a Matchless Spitfire.

The tone stack is a little unusual. It's similar to the Fender stack (for the 18 Watt Lite II) but not really.
It works, but you have to turn the knob to about 8 and then at 9 the volume falls off quickly. I've attached a photo.

I'm also considering adding a triode/pentode switch to lower it to 5 watts, which would be nice for bedroom use.
Does this sound good?
I'm asking because I don't see one on the 18 Watt or Matchless.

Another change would be a master volume.
There's only one stage of gain, so there's two choices:
A pot between the output of the phase splitter
(I've seen this in the Vox AC30 circuit)
A dual pot on each side of the phase splitter.

There's also a 1/2 of an 12AX7, which I could add as a boost stage.
I don't really see a need, however, since the amp screams (although it is a bit loud).

Schematics for the 18 Watt Lite II can be found here
http://www.silvatone.bravepages.com/

Thanks!!

PS - If you're interested in helping me fine tune it, I'll send you a schematic by email or private message. Let me know.
Attached Files
File Type: pdf tone.pdf (16.3 KB, 56 views)
  Reply With Quote
Old 3rd December 2006, 10:26 PM   #2
diyAudio Member
 
Join Date: Feb 2002
Location: Western Sydney
Are you using the correct taper pots?

5W is still too loud for the bedroom, 0.5W would be more like it;

Check out how the master vol is done in this schematic:
http://ampage.org/schematics/spitfire.gif

Cheers,
Pete McK
  Reply With Quote
Old 4th December 2006, 02:47 AM   #3
PRNDL is offline PRNDL  United States
diyAudio Member
 
Join Date: Oct 2006
I see now ... the only difference is the cap from the tone pot to ground.
Mine has 0.1 MF vs .01 -- perhaps that's why the tone control is at 9.

>> 5W is still too loud for the bedroom, 0.5W would be more like it

Yes.

What build are you recommending ... the AX84 FireFly?
  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
Passive 2 band tone stack for guitar SouPortugues Instruments and Amps 9 11th August 2009 03:35 PM
guitar tone I can't find.... screamersusa Instruments and Amps 14 13th June 2009 07:42 PM
replacing tone stack in tube pa for guitar blindbrett Instruments and Amps 5 6th July 2008 09:13 PM
active tone/Buffer for bass guitar?? partyjups Instruments and Amps 9 6th March 2004 03:22 PM
how horrible would a guitar sound through a gainclone without any tone control stuff? travis Instruments and Amps 22 20th October 2003 06:41 AM


New To Site? Need Help?

All times are GMT. The time now is 08:59 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