Info on guitar amps =D

Started by Fras, January 20, 2007, 05:58:49 PM

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Fras

Hi everyone! I was wondering if anyone could point me some useful info when building guitar amplifiers... like, why this *insert a electric function* is used and what it does and so on. I do understand the basics and more about electronics(about 1½ years of electrical education in school), so no need for how components work =D
examples: designing preamps, tone controls, and anything else that might be useful.
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Fras

You begin to #pray. The gods become angry! Your luck is reduced to a crisp.

joecool85

I guess it just seemed a little vague.  I'll take a stab at it, and we can go from there.

Basically your modern guitar amp has a preamp and a poweramp.  The preamp boosts the signal to appropriate levels for the poweramp section.  The poweramp amplifies the signal and drives the speaker.

Within the preamp there is normally at least two parts.  Part one is the tone control section, and part two is the amplification section.  Sometimes people build effects in as well, but I'd rather use a pedal on a "clean" amp than built in effects anyway.
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Fras

That's a pretty good stab  :D

I have no experience at all with guitar amplifiers. I may know how to build a simple amplifier with OP's and create a filter or two but, for example, i have no clue about how to construct a tone control, or making the poweramp go together with the speaker. Now, as I sit here and type, I got the idea of checking out some guitar amp scematics, trying to figure most of it out, but anything other that could be said would help^^
You begin to #pray. The gods become angry! Your luck is reduced to a crisp.

teemuk

Checking out schematics is practically the best way to learn the stuff. Most circuit's recycle ideas that seemed to work and make only little alterations - if any. If you are serious about this, download as much as schematics as you can and study them carefully - and do not limit yourself to guitar amplifiers only. There is a lot of neat stuff in HiFi circuits that the designers could learn from, especially in the power amplifier field. The HiFi stuff is also way better (and more scientifically) documented.

My few advices:
1. Unless you're excellent in circuit theory install a pspice software to your computer and learn how to use it. Simulate all strange looking circuits in the software and see what tweaking different component values will do. Breadboarding and scoping would be even better option but I guess no-one has time for that unless it is their daytime job.
2. Understand that no component is ideal in real-life - that even includes components like wires, solder joints PCB traces, etc. A certain design aspect has always been coping with the unideal behaviour of the circuits; oscillation, heating, ground loop currents etc.
3. Cost: Just because you see a circuit doing something in a commercially famous amplifier doesn't mean it's the best way the do it - It might only be the cheapest way to do it.
4. Find out the terminology so you can use reference books and google more effectively. There is a wealth of information about practically anything related to amplifiers. Learn how to search.
5. Never trust the "guru" information and hearsay. Some people wish to indicate that guitar amp design is art - well, maybe but it's also pure science: All circuit topologies and component value choices in guitar amps can be explained with science. All circuits built by "I feel I should do it this way"-principle can be made better with choices based on science. If you wish to learn science start acquiring information from reliable sources like journal articles and reference books.

Fras

#5
ok, thanks a bunch for all the tips!^^

EDIT: Umm... Where can I find some schematics? I've looked around a little, and only found ones with either tubes or transistors... Where could I find some with OP's? =D
You begin to #pray. The gods become angry! Your luck is reduced to a crisp.


Fras

Wow  ;D  Thanks for the links!
You begin to #pray. The gods become angry! Your luck is reduced to a crisp.

syndromet

Quote from: Fras on January 25, 2007, 10:39:46 AM
ok, thanks a bunch for all the tips!^^

EDIT: Umm... Where can I find some schematics? I've looked around a little, and only found ones with either tubes or transistors... Where could I find some with OP's? =D
There is a lot of good schematics in the schematic section of this page too. Also check out the datasheets of the chips you'd like to use. The usaly have schematics included. Sometimes even PCB layouts.

Fras

You begin to #pray. The gods become angry! Your luck is reduced to a crisp.