I have an Avid Eleven Rack that I want to use as a head. I need a power amp for it and I would like to build one with KT88 power tubes and about 50 to 100 watts. Are there any kits available anywhere or how would I go about learning to build it and find parts. I don't know much about electronics except guitar wiring.
You do know how much this is going to weigh, don't you? And how much heat it's going to put out? The big problem is going to be getting the transformers; well, not really the power transformer, that's pretty standard, but different output transformers sound noticeably different, particularly when you're running into output distortion (and if you're not intending to run the output into a few percent of distortion you might as well get a transistor amp and save your muscles a bit of excess). The output transformer's going to be about your biggest single expense, and you don't want to get it wrong. Perhaps find a guitar amp you like the sound of and see if its output transformer is available as a service component; they do burn out sometimes. And even fifty watts of guitar is ear-splittingly loud (at certain concerts I've had to request a guitarist with a thirty watt amp to aim it at himself while I balanced the level in the PA, because he was overwhelming the vocals and forcing the hall volume into the intolerable).
Remember, Amps like this will be running at potentially lethal volts, that these will hang around in the reservoir capacitors for several minutes after unplugging the amp. This is not a project for the faint hearted. Still, tag board construction means easy modification, your average tube circuit is very modular, easy to see where preamp stages end and power starts, and lots of schemas are easily available; building and punching a chassis solid enough to carry the iron is going to be an interesting project…
Keep us up to date.
Remember, Amps like this will be running at potentially lethal volts, that these will hang around in the reservoir capacitors for several minutes after unplugging the amp. This is not a project for the faint hearted. Still, tag board construction means easy modification, your average tube circuit is very modular, easy to see where preamp stages end and power starts, and lots of schemas are easily available; building and punching a chassis solid enough to carry the iron is going to be an interesting project…
Keep us up to date.
AX84 50W Push-Pull, and change the output tubes to KT88.
Board Layout for above.
Many experienced builders will be able to help you at its forum.
Jaz
Board Layout for above.
Many experienced builders will be able to help you at its forum.
Jaz
I don't know if a tube poweramp for someone who doesn't know all that much about electronics, let alone tubes in general, is the best idea. Lethal voltages, high currents, heat... things can seriously go wrong. I started with preamps to get the hang of it.
If you want to learn about tubes in general (triodes, pentodes, loadlines, phase splitter, feedback, etc. etc.) I can highly recommend 'Designing tube preamps for guitar and bass' by Merlin Blencowe. It's focused at preamps, but much is applicable with poweramps. Check out his site too: http://www.valvewizard.co.uk/
If you want to learn about tubes in general (triodes, pentodes, loadlines, phase splitter, feedback, etc. etc.) I can highly recommend 'Designing tube preamps for guitar and bass' by Merlin Blencowe. It's focused at preamps, but much is applicable with poweramps. Check out his site too: http://www.valvewizard.co.uk/
I have just come up with a 100 watt valve design.
It uses 2 pairs of el34.
It has ecc83 front end driving a tone control then a phase splitter.
There is no feedback loop to try and keep some distortion.
I picked up a Fender output transformer on ebay for £60.
The rest of the parts come from RS Components.
I haven't built it yet so cant comment on the sound.
The circuit is quite big so isn't easy to publish on here.
It uses 2 pairs of el34.
It has ecc83 front end driving a tone control then a phase splitter.
There is no feedback loop to try and keep some distortion.
I picked up a Fender output transformer on ebay for £60.
The rest of the parts come from RS Components.
I haven't built it yet so cant comment on the sound.
The circuit is quite big so isn't easy to publish on here.
You're welcome for the "resurrection"... xD
Some of the Resistors need different values. R12 and R13? Do you happen to know the modifications needed in order for the kt88 to work as they should? (Never worked with kt88s before)
I'm working on a send return on the schematic by the way!
Here's one I've been looking into---you can use either 6L6s or KT88s, and it's fashioned after one of the most iconic amplifiers ever made:
Trinity Trip Top Kit | Trinity Amps
Trinity Trip Top Kit | Trinity Amps
This definitely an affordable kit! But I'm the kind of person who has this tendency to collecting parts on my own xD. There's no layouts and bom around I suppose eh? I'm mainly interested in the tube power section of the amp and not its preamp because I want to add my own preamps and listen to what sounds best.
Even though this is an old thread: Did someone notice that the rotary output impedance selector option in this drawing won't work?
Best regards!
Oh no. Reading your observations, I deleted all the layouts and schems! Now that I figured that I could only do a 8ohm out, the ax84 site is down god knows for how long! Any of you guys have any schematics and layouts for a 2x kt88 guitar power amp? Like the first poster, I intend on using external 9v or 18v preamps with it!
Thanks in advance!
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