Guitar Amp Design / Build - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 27th September 2009, 07:23 PM   #1
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Default Guitar Amp Design / Build

In keeping with another current project (Stratocaster build) I'm building a guitar amp.
Many of the other aspects of it's construction have been decided and I have started by selecting the drivers (two Eminence Legend 1258) and building the box to house it all. Details on this to follow but first the issues that need attention: preamp design and power amp choice.

First, the preamp that I have put together with inspiration from Rod Elliott's design:

GUITAR PREAMP 1.pdf

Basically buffer, gain, tone, gain, buffer.

Room for improvement here? I'm new to this type of thing and any input would be greatly appreciated.
  Reply With Quote
Old 27th September 2009, 07:56 PM   #2
Bone is offline Bone  United Kingdom
diyAudio Member
 
Join Date: Jun 2004
Location: Dorset, UK
You might want to put a single pole switch above or below R14 to disable the diode clipping.

Tony
  Reply With Quote
Old 27th September 2009, 08:17 PM   #3
teemuk is offline teemuk  Finland
diyAudio Member
 
Join Date: Nov 2004
Location: Suomi, Finland
The input buffer seems pointless and has a too low input impedance to begin with. You want input Z to be closer to 1 Megaohm, like in the second stage.

Overall, I don't like the Elliot's preamp design and there are several reasons for this. The clipping diodes are a joke because due to the large bandwidth of the preamplifier they will only develop annoying buzz and fuzz. The only decent tones you'll get from this preamp are clean ones. I would seriously consider ditching this design and taking a look at the preamplifier circuits in some of the guitar amplifiers you are fond of. Study them for a moment and you'll begin to realise how awful the Rod's design actually is for this kind of application.
  Reply With Quote
Old 27th September 2009, 08:19 PM   #4
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Thanks Tony,
Good idea. Any others?

I thought about making the gain adjustable on the input buffer and make away with the hi / lo inputs. What do you think?
  Reply With Quote
Old 27th September 2009, 08:25 PM   #5
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Hi teemuk,
In my usual haste to get things done, I overlooked other designs. I will take a closer look at some of the schematics I've found.

Any recommendations? Remember, I don't know any guitar amps and I don't even know how to play yet.
  Reply With Quote
Old 27th September 2009, 09:43 PM   #6
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
If your looking for harmonics in the design then consider a soft limiter.
This will give a range of tones similar to a valve amp in overdrive.

Click the image to open in full size.

Last edited by nigelwright7557; 27th September 2009 at 09:50 PM.
  Reply With Quote
Old 27th September 2009, 09:46 PM   #7
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
How about this one:

117.jpg

Gibson G50A. It has the features I want. It is mostly discrete but that isn't an obstacle.
  Reply With Quote
Old 27th September 2009, 10:15 PM   #8
tinitus is offline tinitus  Europe
diyAudio Moderator R.I.P.
 
Join Date: Nov 2005
OK
Made me look at these one more time
http://www.guitarmusician.com/tradit...uitar-amps.php
  Reply With Quote
Old 27th September 2009, 11:18 PM   #9
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Hi John; if you design for a lead guitar you need a harmonic enhancer that makes sound brighter when louder, and softer when it decay.

Here is the main idea: Si diodes in feedback (Log. converter), Ge diodes after (Exp. converter). The pot is a pedal ("Expression"): push the pedal and get more drive.


Click the image to open in full size.
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 27th September 2009, 11:48 PM   #10
diyAudio Member
 
Terry Demol's Avatar
 
Join Date: Apr 2002
Location: *
Quote:
Originally Posted by MJL21193 View Post
In keeping with another current project (Stratocaster build) I'm building a guitar amp.
Many of the other aspects of it's construction have been decided and I have started by selecting the drivers (two Eminence Legend 1258) and building the box to house it all. Details on this to follow but first the issues that need attention: preamp design and power amp choice.

First, the preamp that I have put together with inspiration from Rod Elliott's design:

Attachment 142195

Basically buffer, gain, tone, gain, buffer.

Room for improvement here? I'm new to this type of thing and any input would be greatly appreciated.
I would forget the IC topology and do an all tube design.

If your preference is for heavily overdriven sounds then look at some of
the early Marshall master volume model schematics. If you are more of a
clean twang sort of guy then a Fender front end is the way to go.

I also recommend a spring reverb unit, these sound really great and if you
can stretch it a tremolo circuit as per early Fenders.

Good luck

T
  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
i want to build a guitar amplifier elmer Instruments and Amps 24 30th March 2010 05:52 PM
Custom Guitar Build Log LightwaveDude Instruments and Amps 40 31st May 2008 07:12 AM
Guitar amp build... Stormrider Instruments and Amps 6 12th December 2007 01:23 AM
New Build Pics (guitar Amp) Trout Tubes / Valves 15 20th November 2006 08:21 PM
New Build (Guitar Amp) Trout Tubes / Valves 5 17th December 2005 02:30 PM


New To Site? Need Help?

All times are GMT. The time now is 02:05 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