Schematic of a guitar amplifier (200W)

[Weis Guy]

Anybody does have a schematic on guitar amplifier having an output of 200W using 12in speaker?

 

[sinatra]

Re: GUITAR AMPLIFIER

Hello Weis Guy.
There used to be a simple and easy to build design in this link:
**broken link removed**

Unfortunately the link doesn't seem to work anymore.
But fortunately I had saved this into a file and I'm happy to share it with you.

Just make 2 of those amplifiers and connect them in a bridge configuration (this should multiply the output power by a factor of 4! if I'm not wrong). You should easily get more than 200W.

Hope it helps.
S.

 

[btbass]

GUITAR AMPLIFIER

If you want a good sounding Guitar amp, it has to be a valve amp! You will never see a top guitar player use a transistor amp because they sound crap. I suggest you buy 'The Tube Amp Book' published by groove tubes, it is full of all the old classic amplifier designs. 50 Watts of tube power is all you will need. Have you ever heard a VOX AC30 turned up, the volume and power is awesome. Reputedly, the best sounding blues guitar amplifier for all time is the 1958 Fender Bassman with 4 x 10 speakers.

 

[sinatra]

Re: GUITAR AMPLIFIER

I believe it is difficult to get 200W with tubes.
If I'm not wrong 4 tubes type EL34 give about 50W.
I think it will not be so easy to get the desired 200W with tubes as it is with solid-state.

S.

 

[btbass]

GUITAR AMPLIFIER

That is the point, you dont need 200Watts if you have valves. 2 EL34 will give you 50 watts, 4 will give you 100 Watts. But 50 watts is better for lead guitar, you can easily overdrive it and then it comes alive and begins to sing. Im sure the amp design you have linked to is very good for HI-Fi or for a PA system where low distortion is required, but a good guitar sound is about overdrive and distortion. Valve sound overdrive is sweet, transistor overdrive sound is harsh!

 

[Buriedcode]

Re: GUITAR AMPLIFIER

Hi, I'm probably out of my depth here, since I've never built a guitar amp before...

Anyway, 200W is terribly loud! Remember, wattage doesn't necessarily relate directly to volume. I've heard a 50W amp, with medium master volume into a 4x12 cab, couldn't get within 20 feet of it without passing out For a single 12" speaker, I'd go with 50-100W, preferably 60-80.

And about 'overdrive', many people think that the best distortion doesn't only come from the preamp stages, but also the power amp and the speaker. So, thats why so many guitar 'legends' are often seen with small valve amps (10-20W), since these may not be ultra loud, but when really turned up, they get the sound of the speaker and amp really straining, but at moderate volumes (sounds like a 100W marshall with everything on 11 )

Anyway, I've found these webpages:

**broken link removed**
**broken link removed**

Just search google for 'homemade guitar amp', I got a few thousand decent hits.

I don't want to get into a major discussion about this, but...about the 'valve vs solid state thing' A solid-state amp (trasistor, MOSFET etc..) will amplify your guitar faithfully, that is, it will simply make the signal from your guitar louder without colouring the tone. And when overdriven, gets fuzzy and harsh (pantera/weezer/metallica use solid states a lot)..

A valve amp (all valve) on the other hand, does not faithfully amplify the signal, it colours it and changes it, and many many people are pleased with the result. From my experience, that 'valve sound' isn't just down to valves. Since valve amps are designed differently, with output transformers of different impedence, and variable speaker loading. Also, as I mentioned above, valve amps only really get going at very high volumes (pushing power stage and speaker into major overdrive) and thats generally the classic sound, a cranked amp. Do this with a solid-state amp, and the effect is different but alot more similar than most people think, becuase most solid state amps are for beginers and for practicing at low volumes (not ear splitting) so no-one gets to hear a solid-state amp stressed.

Anyway, thats probably completely off the point...I did know a site where a guy built a nice 80W, with great schematics and well thought-out design and hes got loads of sound samples. Plus, its a 4 channel amp with a footswitch for channel control. Can't find the URL, sorry.

Do you have the speaker/cab already? That will probably be the hardest bit, finding the right speaker, since they are specifically designed for guitar (a mid-range instrument), a flat response speaker or HiFi speaker simply won't do, no matter how much it costs.. So many variables its impossible to go through them all, thats why I've never got round to designing/building one.

Good luck,

BuriedCode

 

[Weis Guy]

Re: GUITAR AMPLIFIER

is it ok to use the LEACH AMP for GUITAR AMP?

 

[Buriedcode]

Re: GUITAR AMPLIFIER

Weis Guy,

is it ok to use the LEACH AMP for GUITAR AMP?

I would say maybe... That doesn't mean theres anything really wrong with it, as long as you get the levels right, and have a speaker that matches the output impedence and max power rating, it'll work. From what little I know about 'leach' amps, they're said to be very good power amplifiers, and relatively simple to biuld. But they're not specifically designed for guitar......but as long as you get the right speaker (one FOR guitar) I can't see it doing any harm. Remember, this is a power amp, so if you want to plug your guitar in, you'll probably need a preamp stage, or two, or three....

As far as I know most guitar amps nowdays have 2 preamp stages, and then the power amp. These are needed for impedence matching, and 'some' amplification to get it up to spec for the power amp. One will be needed for a *clean* sound, and 2 will be neeeded for an *overdrive* sound, since the first preamp, overloads the second, distorting it, and then this is amplified for the speaker.

I've said it before, and I'll say it again.....200W? For a 12" speaker, you won't be able to run it at full power. Unless you're planning to wake up the world, got with 100w max. Few guitar amps go over this. (300W for bass guitar amps I think).

Good luck.

BuriedCode