Looking for a simple 60-100 watt amp project

VintageSG

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How keen are you?

For the pre-amp section, there are lots of fairly low voltage examples out there that use valves. Not starved plate exactly, but they're hungry. You can use 6j1 or 6k4 pentodes in triode-strapped mode quite comfortably around ~100V They'll run in pentode mode at that voltage too, but you may not like the clipping.

There are IC amps operating in Class AB/AB1 from the simple ( and really quite awesome ) TDA2030/2050, which will give ~10 Watts/25 Watts reliably clean and 20/40 Watts with tuneful clipping, up to some real beasts with the TDA7294. The 7294 and its ilk have powered many an amp. Heatsink the daylights out of it though, unlike Marshall with the original MG100DFX... CPU heatsinks and fans aint enough. Chip go phut!

https://www.electroschematics.com/tda-amplifier-circuits/#tda7294

If you get really keen, Velleman and Maplin used to make discrete FET amps that'd happily push 100 Watts clean into an 8 Ohm load. get the sound from the pre-amp and use the power stage to lift it, but the old, discrete FET amps sounded quite good as they were. I used to clone a Maplin FET amp board that'd happily push 160 Watts @ 10% into 4 Ohms for installation and PA purposes. You need a 60-0-60 or 80-0-80 for them though, which gets close to valve transformer costs. One of my old bass amps was powered that way. It rocked. The schematics are readily available.

Use the whuftiest toroidal transformer you can for the required voltages. An inductor after the rectifier, before the smoothing caps, is your friend.

AB chips, such as the TDA sound quite good at the onset of clipping. FET stages sound really good. A FET stage into a 1:1 transformer?, magic happens at high volumes as the transformer saturates naturally, just like a valve stage :)

Valve or valve/FET ( even an op-amp or two for the tone stack ) for the initial stages, AB chip amp or FET for the power stage. Class D is -ok- until it clips. Then it sucks.

Have a look at the schematics for Marshall/Park solid state amps for a good starting point.
 

drmordo

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I know exactly what I would do.

Build a Runoffgroove JFET version of a tube amp. Possibly a Supreaux or Eighteen, I have built both and they sound great.

This track is a SG into an Eighteen and power amp thru a 12" speaker. http://the23rdcentury.org/Orphans/Jumping Jack Flash.mp3 I recorded that solely because I loved the Marshall sound of that pedal so much and wanted to record something with it.

If you are building single coil Tele, I might build the Professor Tweed (click the Azabache link) or Britannia (though I have built the English Channel and loved it, so might go that route again). I prefer single coils thru a Fender or Vox.

Link: http://www.runoffgroove.com/articles.html

Then feed it into a SS power amp, Class D if I built it or I'd just buy a cheap PA power amp. I might buy a cheap Class D from amazon as well.
 
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King Fan

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I'm still looking at the 'why' piece for the OP. Why SS? To get the 100W rehearsal amp? Because it's what you know? Or some other reason?
 
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printer2

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It will work - for a while. If you are running the amp loud, the IC will heat up and eventually shut itself off. They tend to "stutter" as they cool then heat up again. They need a heatsink, just not as big of one as a class AB amp.

Yes. It is always good to go big with a Class D amp. Adding a little extra cooling, even a small cpu fan blowing at it is good.
 

printer2

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The OP might want to have a look at the Solid State Guitar Amp Forum
https://www.ssguitar.com/

I never found much of interest there. I am thinking the OP is looking for something to boost his pedal sounds. Mind you many pedals think the amp will have a scooped midrange built in. It is a good case of, "It Depends."

On a similar note, this got me to look at the chips I got, what for boards, go bridged, wasted hours on it. Darn, and I was not even thinking of building an amp with them. A +/- 35V supply with one might really rock. But do I need it?
 

2L man

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Me too think that building "solid state power" nowadays is not time and money worth because D-class amp "cards" are cheap and sometimes free when people replace HiFi. Computer power supplys can also be found free.

However building transistor amps can be as revarding as tube amp building and obviously they can sound great as well. There are interesting 1960s schematics where Germanium power transistors were used together with signal and output transformers sometimes on A-class.

I have collect germanium signal transistors for fuzzface builds but also TO-3 power transistors which I might some day use on guitar amps. There are lots of signal transformers but not much low winding ratio output transformers but I think "line transformers" could be used. And DIY winding transformers is not difficult.
 

printer2

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Me too think that building "solid state power" nowadays is not time and money worth because D-class amp "cards" are cheap and sometimes free when people replace HiFi. Computer power supplys can also be found free.

However building transistor amps can be as revarding as tube amp building and obviously they can sound great as well. There are interesting 1960s schematics where Germanium power transistors were used together with signal and output transformers sometimes on A-class.

I have collect germanium signal transistors for fuzzface builds but also TO-3 power transistors which I might some day use on guitar amps. There are lots of signal transformers but not much low winding ratio output transformers but I think "line transformers" could be used. And DIY winding transformers is not difficult.

Probably not in the realm of what the OP is looking for (germanium and output transformer). I do have a PA amp (think medium size office paging) that has the P-P transformers driving an output transformer. I was thinking of one day doing a silly thing like building a transistor amp with each stage capacitor coupled and minimal NFB. So many ideas, so little time.
 

Pencilman

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I'm still looking at the 'why' piece for the OP. Why SS? To get the 100W rehearsal amp? Because it's what you know? Or some other reason?

Yeesh... I see I've opened the Pandora's box on this one. The only reason I wanted to do a SS amp is because I deemed it cheaper, safer and easier. After reading all the comments I see I was wrong. I'll put off building an amp for now, since I see I would still spend considerably more then I am currently willing to.

Also just to add insult to injury I concede that tube amps are probably the better way to go but I'm also one of those weird people that think that SS amps are not useless. Brian May used one for his entire career in the studio. Granted it was only in the studio but no one is questioning his decisions either :p.
 

King Fan

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Yeesh... I see I've opened the Pandora's box on this one. The only reason I wanted to do a SS amp is because I deemed it cheaper, safer and easier. After reading all the comments I see I was wrong.

Sorry! I didn't mean to question your logic. (OK, '100W rehearsal amp' was unkind, I know -- but that hinted to me you maybe thought SS was the 'usual' way). It's just like we were all starting to act like you were determined to build SS, and I wondered if in fact your reasons might be different, as you say here.

Don't tell anyone else, but I agree solid state isn't useless. Hey, one of my fave old-school guitarists, Albert King, was a user. I'm not getting into the endless SS-v-tube thing at all. But as you're seeing, to "DIY" at the circuit / component level, it's hard to reproduce the actual building of a solid-state amp.
 

FenderLover

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I would skirt the whole "building of solid state" and just order a Class D power amp. They are plug and play. Power supply, input, output. Any pedal board/stomp pedal serves as a preamp.

Now you're making me want to build one. Look at the Ibanez amp from a couple years back - their preamp is literally a TS-9. Go to a volume knob > class D amp > speaker jack.
 

ArcticWhite

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Yeesh... I see I've opened the Pandora's box on this one. The only reason I wanted to do a SS amp is because I deemed it cheaper, safer and easier. After reading all the comments I see I was wrong. I'll put off building an amp for now, since I see I would still spend considerably more then I am currently willing to.

Also just to add insult to injury I concede that tube amps are probably the better way to go but I'm also one of those weird people that think that SS amps are not useless. Brian May used one for his entire career in the studio. Granted it was only in the studio but no one is questioning his decisions either :p.
Brian's amp was a one of a kind "Deacy" amp which used germanium transistors for amplification. Germaniums have many of the quirky characteristics that we tend to love in vacuum tubes, mostly smooth and warm distortion, added harmonics, and soft clipping.
 

Pencilman

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Brian's amp was a one of a kind "Deacy" amp which used germanium transistors for amplification. Germaniums have many of the quirky characteristics that we tend to love in vacuum tubes, mostly smooth and warm distortion, added harmonics, and soft clipping.

Ok that may be, but there are also a lot of other famous guitarists that use SS amps. Andy Summers, John Fogerty, Paul Landers, Billy Gibbons, etc. I really never understood the hate for SS amps. They have their place.
 

2L man

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Often nowadays instruments come thru PA, which is D-class, full frequency system anyway. Sometimes artist want a microphone(s) after stage setup loudspeaker and sometimes signal go hard wired to PA.

So it is fine to use any kind of "effects" made of tubes, transformers loudspeakers (read: traditional tube amps) or various transistors, OP-amps or digital modeler systems which current effect boxes often are.
 

ArcticWhite

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Ok that may be, but there are also a lot of other famous guitarists that use SS amps. Andy Summers, John Fogerty, Paul Landers, Billy Gibbons, etc. I really never understood the hate for SS amps. They have their place.
This thread is all over the place.
Go ahead and build a SS amp then.
Have fun.
 

Pencilman

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This thread is all over the place.
Go ahead and build a SS amp then.
Have fun.

I already said I will not but people seem to think it necessary to keep repeating that it's a bad idea. I'm not trying to be hostile, I just find it funny how fast some people got on my case because I just mentioned the idea of building a SS amp. Maybe I just perceived it wrong, sorry if I missread anything. I think it's best if an Admin closes this thread. I think it has the potential of escalating in to something I never intended.
 




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