Basic Amp Build for teaching electronics

[Jockster]

Hi, I am a Physics teacher and guitar player. I have some students (14-16) who are also guitar players and also interested in electronics/building stuff. Next year I want to undertake a project with them to get them to build a really simple amp, just to get them enthusiastic about building stuff and electronics. Can anyone suggest a really simple amp project that may be suitable. Cost will obviously be an issue. I have some very limited electronics experience so simple is better. Many thanks for any help you can give, thanks Simon

[rjb]

Maybe an LM386-based kit?
Tayda sells a PCB, but you have to buy all the parts separately.
I emailed a while ago, and was told they will be selling packaged kits "soon".
But you may be able to get kits directly from the manufacturer, DH Electro Acoustic (ref P/N DHB8).

Mini Guitar Amp DIY PCB Guitar Effect
Mini Guitar Amp
Kits - DH *Electro Acoustics

-rb

PS
Check out this thread: http://music-electronics-forum.com/t44195/

[eschertron]

Many of today's designs use op-amps and other low voltage components. Safe for students and easy on the liability issues.

A guitar amp can be considered as a collection of a few basic 'blocks'. Power supply, input amplifier and tone controls (preamp), and power amp. These 'blocks', pursued in this order, can bring some gratification to the budding enthusiast as each section is built, long before the entire guitar amp is realized. My first encounter with music electronics (in college, I envy your students!) consisted of learning to read schematics for the functional units, such as the power supply, tone controls, etc., that I mentioned above. As a source for such schematics (to read, not necessarily to build), try http://music-electronics-forum.com/t19518/ located on this forum. Many Fender amps are tube, but many are also solid-state, and would be good for getting a peek under the hood.

Others will chime in with specific examples to research and to build. Keep us posted!

[Justin Thomas]

Welcome to the place! First question, where are you located?

Second, what exactly would be your budget? Would you be looking at very simple tube amps, or are there voltage/current limitations? Would each student build an amp, or do you mean one for the group?

If for a group project, I would actually say a small EL84 amp would be good - a Matchless Spitfire? Very simple circuit, yet enough features to learn about and experiment with - 1 preamp stage, Volume, Tone control, a phase inverter, and the output stage... The parts would be fairly cheap - no need use designer components. I used a recycled Stromberg PA for mine, so parts only cost $70, but even with transformers and chassis, I bet the total could be less than $300. I also did mine true point-to-point. There's also a good history of support for these builds on this forum from a while back.

The amp itself has nice cleans, nice distortion, and isn't a "high-gain" uber-buzz-box. The tones it makes would still be considered "useful" and would span multiple genres and styles, rather than just being a "flavor-of-the-year" sound.

My experience building amps has been that the worst expense is actually the cabinets and speakers... Maybe some of this helps, maybe I'm way off base...

Justin

[Jockster]

Hi, many thanks for the quick replies, much appreciated.

I am located in the UK, near Manchester.
Ideally max $200 per-amp.
1 amp per student.

Just going to spend sometime reading through replies in detail and will post again with my thoughts.

Once again many thanks for the help, cheers, Simon

[Enzo]

I'd recommend against a tube project for school kids. They cost more, and the voltage is a danger that I doubt the school system would want to involve itself with. A small solid state amp would be easy to make and inexpensive. And no specialty suppliers would be needed. Solid state parts you could get from RS or Farnell, while tubes and related parts are available mainly through guitar amp suppliers.

If these kids are already guitar players, do they already have amps? Might they be interested in some effect pedal like an over drive pedal? Those are also made of simple common parts, are small projects easily accomplished.

[g1]

Also, effects pedals run on batteries or external wall-wart type power supplies, which takes the whole power supply (and any such liability) out of the equation.

[rjb]

A 1/2W Ruby amp also runs on a 9V battery.
Hey, what kid doesn't want a belt loop amplifier? :clueless:

[Enzo]

Sure, a Scholz Rockman is always lots of fun.

[Mick Bailey]

I carry out quite a few equipment repairs for the OP's target age range, plus also deal with quite a few guitar teaching staff who are based in schools. In my opinion (which I know you didn't ask for), a small amp would be a momentary distraction. Makes a sound, but flat and lifeless. I call them 'spud' amps - as interesting as a spud to the over-stimulated 'now' generation.

An FX unit - maybe a simple fuzz (even a Bazz Fuss perhaps) -may be of more interest. Low component count and involves assembly/soldering, but really useful as a 'keeper' and something to get continued use out of, even in a band situation. I have experienced, gigging musicians that have one on their pedal board.

Low cost, too.

[rjb]

I yield to the man who knows his target audience.

But I still want a wearable busking amp for myself.

[Mick Bailey]

I heard a kid playing through his phone and hardly believed the sound - chorus, reverb, delay, channel switching, the lot. Plenty loud enough, too. By comparison a DIY chip amp sounds like cardboard.

[rjb]

I had been considering making a snarky remark like "Why bother building any of this stuff when there's probably a smartphone app for it".
Apparently, there is. I need to get out more.

-rb

Edit:
Is the "cardboard sound" more a function of the amp's circuitry, or of the tiny inefficient speakers they are usually paired with?

[Justin Thomas]

I don't say any of this to discourage the OP's project, only to simply encourage them to not just accept what's culturally given as the final ideal. Since I see this project being intended as a springboard into greater things, I truly hope it serves its intended purpose and then some. That said, there's a whole lot more out there, and I think rjb's comment sums up much:

I had been considering making a snarky remark like "Why bother building any of this stuff when there's probably a smartphone app for it".
Apparently, there is. I need to get out more.

The more I "hear" the substitutes offered & proffered for real moving-air analog amplifiers (of which we are becoming more and more afraid), the more the substitutes "sound" okay... But they don't FEEL the same, and they carry no authority. It's not just about how loud you can play your app or profiler through the house mega-PA... something is lost in it all. And they get lost when pitted against a real drum kit.

I have no studies, and I know that "specs are specs," etc., so I'm not going to fight and "prove my opinion." I don't have the chops to do it. But I can't settle for the assertion that EVERYthing is ultimately measurable... And in the hands of a true master, it doesn't matter what THEY play through. Those are exceptionally rare, and they generally end up sacrificing, fighting, and warring to get what they think will make them sound better. And the rest of us settle for inferior tools and sounds. Clinical, plastic, sterile - lots of neat "tricks," but just so empty and lifeless...

Justin

[nosaj]

I don't say any of this to discourage the OP's project, only to simply encourage them to not just accept what's culturally given as the final ideal. Since I see this project being intended as a springboard into greater things, I truly hope it serves its intended purpose and then some. That said, there's a whole lot more out there, and I think rjb's comment sums up much:



The more I "hear" the substitutes offered & proffered for real moving-air analog amplifiers (of which we are becoming more and more afraid), the more the substitutes "sound" okay... But they don't FEEL the same, and they carry no authority. It's not just about how loud you can play your app or profiler through the house mega-PA... something is lost in it all. And they get lost when pitted against a real drum kit.

I have no studies, and I know that "specs are specs," etc., so I'm not going to fight and "prove my opinion." I don't have the chops to do it. But I can't settle for the assertion that EVERYthing is ultimately measurable... And in the hands of a true master, it doesn't matter what THEY play through. Those are exceptionally rare, and they generally end up sacrificing, fighting, and warring to get what they think will make them sound better. And the rest of us settle for inferior tools and sounds. Clinical, plastic, sterile - lots of neat "tricks," but just so empty and lifeless...

Justin

Your getting old Justin yearning for the old days......

nosaj