Official Luthiers Forum!

Decided to finally get around to this amp build.
Been carting parts around for a few years.
It's from a free plan from the Angela Instruments website.
It's the Super Single ended plan, which I've already made one of,
and really like it.
Interesting design because it has 2 power tubes,
and 2 rectifier tubes, wired in series, ( I think).
Anyway, got the parts I have had, and need a few more.
The power tranny is a Super Champ one,
and doesn't have a heater out for a rectifier tube,
so I'll use a solid state plug in type.
Any interest in this build,
or should I just shut up!

Interested?

Heck yeah! I've always liked the Angela circuits but didn't have the guts to try one myself.

Build on Alan.

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John Lewis
Wannabe builder owned by 2 crazy dachshunds

Nice thing about amp building is it goes pretty fast.
I have 2 1/2 hours into it and look where I am.
Need to spend another $150 on parts, so might be a while.

I can barely wire a guitar, if I tried to wire an amp things would explode.

Interest? Yes.

I'd like to see more of this.

Kevin Looker

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I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Definitely interested. But i wish you'd actually make it a real build thread, and go step by step.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Lotsa interest here I've thought about trying to tackle building a tube amp someday, I just need someone to show me that it isn't as hard as I make it out to be in my head...

Go man, go! I got parts on the bench too, and it may be 3 years before I get to 'em! I'll just "build" vicariously thru you!

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http://www.presnallguitars.com

Okay.
I'll back up a bit,
go through the safety stuff,
and go fom there.

Safety stuff is very important.
I would like to try tackling something like this, but I have zero understanding of how amps work. Especially tube, which is what I'd want to build if i was building. The more of this kind of stuff I can see, the better.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Bring it on, Alan!
I`d like to see how much about amplifier cicuits I`ve forgotten over the last 30 years.
Coe Franklin

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Give me 50 cents worth of regular.
Check my oil too, if you don`t mind,,,

For sure!
A step-by step would be very cool!

First thing you gotta do is ask yourself if you want to spend $500 or so,
on an amp that you probably couldn't even sell for that much.
You're better off buying an old Fender, which will go up in value.
Next, start with a simple circuit, like the single ended amp on the Angela Instruments site.
I'll put a link in for you sometime.
Or, you could buy a kit.
The Fender amp field guide has schematics and chassis layouts for all
the old Fender amps.
Take a lot of time looking at the chassis layouts on old Tweed Princetons.
Soon it starts making some sense.
I still wouldn't be able to build from just a schematic,
but use them for getting the right values for the components.
I'll go out and take a few shots of what I did yesterday.

So, once you have a circuit you like, that you think you could make,
make a mock up chassis the size of your chassis, make sure things will all fit.
Quadruple check that the wiring diagram is right.
Then layout your chassis to match the mock up.
I used a step drill bit to drill all the holes, and a jigsaw to cut the square out for the power transformer.
The last pic is where the danger starts.
The Power tranny is where the 120 volt AC comes into the amp.
The red wires on this one are putting out 318 volts AC.
The green ones are putting out 6.3 volts AC.
If this was a tube rectifier tranny, the 2 other wires would usually have two 5 volt wires.
When working on a plugged in tranny, or completed amp,
Wear rubber soled shoes, and stand on a rubber mat.
Read safety guidelines which are all over the internet for working with electricity.
Yer on your own there!
Next I'll explain what all those different voltages do.

This is cool! I just need popcorn. Or
As to the cost, yeah I've done some research, and it's definitely not the cheap route. But hey, I build electric guitars and basses. Be nice to eventually add a nice amp to that resume'.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

I'm very interested in building amps. Can't say I'll ever get up the ambition to do one...but still interested

I love tube amps. Cool thread.

Sweet!
Replicas like that are way beyond me. I'd just like to build a nice tube amp (15-25w) based on either a Fender or Marshall design, with a full tone stack and reverb, and a 12" speaker. I know there are kits like that out there all over the place. I just need to keep absorbing as much info about building them as I can. Sooner or later, enough of it will stick into my head and start making sense. That's when I'll start planning the build. Until then, I'll just live vicariously through threads like this one, LOL.

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Mike

The only thing nescessary for evil to thrive is for good men to do nothing.

Nice Filippo!
How many watts is that, and have you ever cranked it all the way up?
I bet it's LOUD!
One thing I like about the 5-12 watt jobs is you can turn it up all the way,
and the tubes can really do their thang, and not be too loud.
I learned a 12 watt Princeton isn't twice as loud as a 6 watt Champ.
I play wineries and small clubs,
and they both have enough power.
No, I don't play metal.
No new pics on the build, since I need parts.
Made some stupid mistakes that needed re-doing,
and I'm staring at the chassis layout to remind me what I need to do.
Anyway, back to what the tubes are doing.
The 6.3 voltage coming off the P.T. (power transformer) lights up heaters in the tubes.
When the tube glows, doesn't mean the tube is good, just the heaters are good.
Simple explaination of a tube is this,
guitar signal (tiny) comes into a pre-amp tube, say a 12ax7.
It connects to a pin which is connected to a grid in the tube, between a cathode and a plate.
Another pin is connected to a cathode, which is a coated piece of metal.
Electrons are excited when heated up (by the tube heaters),
and jump across the grid, to the plate side of the tube, which is connected to a pin as well,
where the signal leaving is "amplified".
Turn your vol on the guitar up or down,
and it makes the grid let more or less electrons through it.
When the coating on the cathode in the tube wears away,
the tube wears out.
Enough for now...
Is it too boring for ya?

I'm right there with you! Rarely does one ever have to wait for glue to set while building an amp. Sounds like an interesting build... I'll have to check it out.

I've built a bunch of amps; the craziest of them being my 100w HiWatt clone (later converted to 50w):

Drat! I thought I had a gut shot... I don't. Well just trust me when I say it looks like insanity.

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Mike Hoenerhoff
Elderly Instruments

i just finished converting an Epiphone Valve Junior into an RH 84 SE "hi fi" last night....
you can score old stereos/organ amps off of ebay for very cheap and rebuild them into fine guitar amps. i made a Marshall 18 watt circuit that way; you could easily build a classic circuit for $100 and less; it just won't look like the "real thing", cosmetically

What started my amp building thing is I bought an old Bogen tube PA,
for $10. It didn't work, so I poked around with a voltmeter and found a bad resistor.
Fixed it, and said to meself "I could build one of these simple tube circuits".
I then bought about 3 old Dukane PA's, and recapped them, and they sound great.
About $50 a piece.
One of the Dukanes I took apart, used as many parts as I could, and built the Super single ended amp.
Kind of a Frankenstein.
I did have to pay an amp guy $300 to finish it, cuz the voltage was WAY too high on the power tubes!
That amp is a real "honker"!

So I haven't done too much on this, except re-doing things.
I got the power switch on the left, standby switch on the right,
power supply cord in as well as the fuse holder.
The tube socket with the red wires from the PT is where 320 volts AC,
will be converted to 320 volts DC with a plug in rectifier.
If this had a rectifier tube, the tube would convert the AC to DC.
Solid state rectified amps sound cleaner.
The grounding wires (yellow) also got one end installed to the grounding buss.
I cleaned the inside of the Frankenstein amp,
and you can see the 2 5U4 rectifier tubes in back,
the 2 5881 (6L6), which are power tubes,
and the 6SL7 preamp tube on the left.
You can swap out the 6SL7 by yanking it out,
and plugging in a 12AX7 in the smaller tube socket.
I prefer the 6SL7, as it sounds fuller.

So, I ran into a little problem with the high voltage AC leads coming out of the PT.
There is no center tap, which taps in between the 2 high voltage 320 (red wires).
So, my plan to use a plug in rectifier won't work!
I need a ground end on the high voltage DC to have a voltage difference.
So, I looked at the super champ schematic, and they use what's called a diode bridge rectifier.
I have some diodes, 4 of them, and they let the current flow in one direction only.
I made one (look at the picture),
and plugged into a 120 outlet, and tested the DC on the ends of the diodes, and it works!
I need to get the right value diodes (800 volts) for the high voltage in the amp.
Basically, the left side of the diode rectifier is the negative, and the right side is positive.
Also, an example of safety is, before you plug anything in to test,
look at what yer testing, make sure no wires are touching each other,
then test away. If you are experienced with working on hot circuits, you can touch the voltmeter probes to the wires.
If you don't feel easy about that, use clamp on ends, like in the second picture, THEN plug it in.
It's just like working with power tools.
Oh, what will happens is, the left side of the bridge rectifier will go to the ground of the amp,
and the other end will go to the positive lead on the big capacitor,
which I don't have YET!

So, the amp build is on hold for now,
for a number of reasons.
Reason #1- the power transformer I have is not the best one for this amp design.
#2- I don't want to spend money on an amp I really don't need ( I already have 2).
#3- I need to do a lot more research about grounding tube circuits.
Someday I'll get the right transformers for this build,
and continue on from there.