Diy Distortion Pedal - 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 31st May 2006, 02:36 PM   #1
diyAudio Member
 
Join Date: Mar 2006
Location: Michigan
Default Diy Distortion Pedal

Hey, I am a Hi-Fi guy, but my friend has recently been bugging me about making a tube distortoin pedal. I don't even know really how a distortion pedal works beyond the fact that it just overdrives the prestage before the power amp (every Hi-fi-er crys a little when they hear how it works). Is there anything more to the functioning of a distortion pedal? Does anyone have a good shcematic for one?
  Reply With Quote
Old 31st May 2006, 03:59 PM   #2
diyAudio Member
 
Kofi Annan's Avatar
 
Join Date: Jan 2004
Location: US
How about The Real McTube?

Haven't heard it, but it looks like it would fit the bill. Cheap too.

Kofi
  Reply With Quote
Old 31st May 2006, 04:37 PM   #3
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
Unfortunatly the real McTube sounds like nothing more than a cheap fuzz box, UNLESS you tweak those anode resistors down, and get the bias just right, then it's ok. There are alot of other valve based pedalsout there, the Tube Driver, Stack in a box, Radio-Head, shaka tube,...
But at the end of the day, you can't get decent distortion form a pedal (valve or otherwise). There's a lot to be said for the mini 1Watt valve amps such as the Firefly at www.ax84.com, Moonlight at http://www.amptone.com/delftmoonlightamp.htm and another whose name i have forgotten- higherwatt or something. These can be cranked right up, but easily casced via a line out into a regular guitar amp.
  Reply With Quote
Old 31st May 2006, 04:40 PM   #4
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
Oh yeah, the other one I was thinking of is the Heaveywatter at http://www.sonicdeli.com/ThunderTweakWeb/links.htm#
  Reply With Quote
Old 31st May 2006, 05:15 PM   #5
diyAudio Member
 
Join Date: Mar 2006
Location: Michigan
I looked at the Real McTube, It looks simple enough, however I really like the concept of a "Wal-Mart" power supply.

What kind of tweaks with the Anode resistors?

I have the spare parts lying around to make a 1.5watt SET out of an El84, would that work just as well?
  Reply With Quote
Old 31st May 2006, 05:16 PM   #6
teemuk is offline teemuk  Finland
diyAudio Member
 
Join Date: Nov 2004
Location: Suomi, Finland
So much for tube tone. I could write a whole book about this topic but in short the type of active device used for gain has little or nothing to do with the tone of distortion. The idea is to always pre filter the signal before overdriving a gain stage to clip. After overdriving the signal should be post filtered. Both are done to voice the distortion so it will not be only bass dominated fuzz or treble dominated tablesaw tone. Instead of overdriving the signal to clip, the signal could be clipped with other ways as well. The idea, however, is always to clip the signal somehow. An educating experience is to put a graphical EQ in front and after a distorting amplifier stage and play with the sliders.

If you overdrive a tube stage loaded by constant resistance there will not be much difference in distortion compared to distortion acquired by overdriving transistors or fets. Tubes will clip with less harder "knee" but that´s about it. If you want a harsher tone you will eventually find yourself just overdriving the tube more. The same round knee can be acquired with solid state devices as well. With tubes the idea is to acquire so called "power amp distortion". To get this you have to overdrive a gain stage loaded by impedance that mimicks the one of speaker load's. In comparison to loading the stage with a constant resistance this will give a notable boost on both higher frequencies and at the frequency that corresponds the speaker's resonance. The same thing can be done with solid state devices, however, the rounder knee of clipping would have to be simulated by other means.

As you said, you lack experience about distortion pedals - or distortion circuits in general. I'm not too keen on repeating myself everytime a similar topic becomes under discussion - and i doubt no one is - so your best bet is to search. The internet is full of information about this, even this forum is. About few weeks ago there was a thread about a similar thing in "Musical instruments" section and it raised few interesting topics. Here´s the link:

Is it possible to get "tube sound" with just a tube preamp and chipamp output?
  Reply With Quote
Old 31st May 2006, 07:08 PM   #7
Merlinb is offline Merlinb  United Kingdom
diyAudio Member
 
Merlinb's Avatar
 
Join Date: May 2006
Location: Lancashire
You can use the wall-wart power supply for a 1 watt valve amp as well as pedals, since the current demands aren't very high.

Obviously an amp made using your EL84 bits will work great, but it's entering the realms of an actual amp, not just a small distortion modelling tool. I guess it depends what your friend really wants.

I have to disagree with teemuk, the nature of distortion generated by valves is not attainable with solid state (well, maybe if you designed a circuit the size of a suitcase that would simulate just one triode stage!). The reason being, a significant portion of the classic valve drive sound is due to the nature of forward grid current. There is no analogous solid state device that has this characteristic, so it you want the real thing, you have to use the real thing!
  Reply With Quote
Old 31st May 2006, 09:44 PM   #8
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Since my name is Tubelab, I really hate to admit this. My favorite simple fuzz box runs on transistors. I first got to play a Vox Tone Bender back in 1970. It makes a sound that is hard to duplicate. I actually took that unit apart and traced the schematic. I built a copy for the guy who let me take his apart, and I made one for myself. I still have it. I have seen the circuit on the web. The same circuit was used in the Dallas Arbiter Fuzz Face (Jimi Hendrix). It is a very simple two transistor circuit.

The secret to making this work is to find two germanium PNP transistors. It will work with silicon transistors, but it doesn't make the same sound. I put sockets in the pc board, and tried several until it sounded sweet. The ones that I used came from an old Sony transistor radio.

I have fance DSP distortion boxes, and an ADA MP-1 vacuum tube guitar preamp which has some very good sounds, but is way too complicated to copy, and is HIGHLY MICROPHONIC! Too much gain in front of your guitar amp will be microphonic (you can't use it loud on stage kind of microphonic).

The Tone bender has the best sound of the bunch.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 31st May 2006, 11:35 PM   #9
Trout is online now Trout  United States
diyAudio Member
 
Trout's Avatar
 
Join Date: Nov 2004
Location: Midwest Madman
You guys are going to make me ill LOL

I just started a distortion mod thread moments ago.

My favorite Pedal is the old vintage tube Hughes Kettner Tubeman my brother has. Its the only unit I ever tried that sounded correctly IMHO.
But I have not tried all the ones listed here either.
Gene
  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
Distortion pedal schematics. Jexx Instruments and Amps 2 11th June 2006 10:48 PM
Need help on moding a distortion pedal Ahmad_tbp Solid State 2 20th February 2006 10:17 AM
blew my amp because of distortion pedal 9am53 Tubes / Valves 3 16th March 2005 08:31 PM
designing my own distortion pedal nico6969 Everything Else 1 18th July 2002 03:06 AM


New To Site? Need Help?

All times are GMT. The time now is 02:51 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