A guitar amp build

[Sambo311]

I want to roll my own guitar amp, I'm not into much of the theory of electronics thats why I need some help. I took electronics in high school but most everything still had tubes in them, we never learned or worked on anything with transistors and I don't work on electronics as a job, its only a hobby. I already figured out the preamp, tone control, reverb and vibrato and got it to work. I want to use 4 LM12CLK op amps as the outputs. I've found schematics using one of these devices, which outputs about 80 watts. I have 4 of them I bought years ago to build a 4 channel car amp and found it was easier and cheaper just to buy an amp already made. The power supply was very complicated and I couldn't track down a toroid core, this was before computers. These devices are hard to come by and are very expensive if not obsolete. I was reading where they were used in some high end audio equipment and as motor drivers. My question is how to connect them in a push pull parallel arrangement for more power and less distortion. They are in a TO-3 case but have 4 leads. I know I'll need a beefy power supply and heat sinks. I already built an almost identical amp using the same preamps, tone control etc. but used a 1969 Dukane 180 watt PA amp that uses 8 2N3055's for an output amp. It has the same woofers in it but has 2 midrange horns and 6 piezeo tweeters, the wife don't like when I turn on that thing. It can blow away most all commercially bought amps. Several monts ago I found a 1966 Heathkit Harmony amp and restored it, all new electronics, speakers, repaired and recovered the cabinet and grille that sounds great but only is about 20 watts. Hope someone out there can help. Have a Happy Holiday.

[soundguruman]

The first obstacle you need to overcome, is to let go of the transistors...search your feelings.....you know it's true.

[DrGonz78]

To me... let go of transistors only if your holding onto an idea to build some tube amps. However, Electronics is Tube or Transistor... I think to be educated on both fronts is the way to go. So many people I hear say "I am good with tube amps but these transistors are just the devils lettuce!!" I mean seriously YES!! TUBE amps are great!! They are the bee's knees, the cats pajamas, and what ever else you want to call it. It's all relative to the person who is learning...

Just learn about electronics without any precondition of tubes are better than transistors! Don't let anyone tell you to "Search your Feelings" I mean seriously it's like comparing your wife or girlfriend to a Porn star!! Yup I have yet to build anything of that matter but I love working on transistor based equipment. So I take stock in the comment that it is an obstacle to overcome. To me learning it all is an obstacle. Not only are you not helping the person learn from where they are starting... You are not listening to the question that they have posted... So we should all think like this? Lend me a gun to shoot myself then...

[eschertron]

I want to roll my own guitar amp, I'm not into much of the theory of electronics thats why I need some help. I took electronics in high school but most everything still had tubes in them, we never learned or worked on anything with transistors and I don't work on electronics as a job, its only a hobby. I already figured out the preamp, tone control, reverb and vibrato and got it to work. I want to use 4 LM12CLK op amps as the outputs. I've found schematics using one of these devices, which outputs about 80 watts. I have 4 of them I bought years ago to build a 4 channel car amp and found it was easier and cheaper just to buy an amp already made. The power supply was very complicated and I couldn't track down a toroid core, this was before computers. These devices are hard to come by and are very expensive if not obsolete. I was reading where they were used in some high end audio equipment and as motor drivers. My question is how to connect them in a push pull parallel arrangement for more power and less distortion. They are in a TO-3 case but have 4 leads. I know I'll need a beefy power supply and heat sinks. I already built an almost identical amp using the same preamps, tone control etc. but used a 1969 Dukane 180 watt PA amp that uses 8 2N3055's for an output amp. It has the same woofers in it but has 2 midrange horns and 6 piezeo tweeters, the wife don't like when I turn on that thing. It can blow away most all commercially bought amps. Several monts ago I found a 1966 Heathkit Harmony amp and restored it, all new electronics, speakers, repaired and recovered the cabinet and grille that sounds great but only is about 20 watts. Hope someone out there can help. Have a Happy Holiday.

A quick google reveals 'some' info about them. I see a link to DIYAUDIO and other sites that may have the info that you are looking for. Other than being a big honking op amp, I don't see any significant difference from other op amps in general. Good luck with your project!

[J M Fahey]

I would consider them beefy LM3886 in TO3 metallic package and make an amp accordingly.
I'd build a stereo 70+70W which is ample guitar power *anywhere* , and keep 2 LM12 as spares.
Parallel bridge circuits are a great Lab experiment which tend to die a quick and sudden death in the Music Instrument world, the classic example being the ill fated Marshall MF350.
The problem is that when even 1 of the LM12 fails, you'll have to send it to a landfill or pay a fortune to get another out of EBay, while my suggestion is safer and you still have 2 spares, just in case.
As of a PSU, a simple to get 2x22V 200/250VA transformer (EI or Toroid) + a bridge + 4x4700uFx35 (or more) will provide ample juice.

[soundguruman]

Transistors are evil. hahahahahahh!

[Gtr_tech]

If you want to be really knowledgeable in guitar amps, you need to know both SS and tube electronics theory. A lot of tube amps contain a decent amount of SS circuitry....whether it be op amps, jfet switching, or whatever. It pays to know both areas to really get the most for your efforts.

[soundguruman]

If you want to be really knowledgeable in guitar amps, you need to know both SS and tube electronics theory. A lot of tube amps contain a decent amount of SS circuitry....whether it be op amps, jfet switching, or whatever. It pays to know both areas to really get the most for your efforts.

Confess your crimes of heresy...
Just once, I wanna see you guys make a switching circuit with tubes instead of J111, hahahahah!

[Gtr_tech]

Oh yea bud...I'll get RIGHT on that

[soundguruman]

Oh yea bud...I'll get RIGHT on that

I will never join the dark side.