new build ideas

[mark enger]

Iv built fender 5e3 and iv built a 5e3 with 6l6s which i guess is a 5e5, i really like the 6l6 deluxe great tone and volume but id like to build something with a little more control optains than vol tone vol, maybe something with treble mids bass and a presence but with cathiod bias any adeas i need a build with a layout something thats been done and has at least some info i can fall back on, ive built lots of marshalls and im getting kinda tired of the el84 thing, ive got plenty of iron that will get me 430 even up to 500v, i just need a little help getting started then ill run with it thanks mark

[loudthud]

On what level do you build your amps? Do you make your own chassis, eyelet board, and/or cabinet?

If you must have a mid control, your choices are limited. The only Fender tweeds I can think of are the 5F6 (-A) and 5F8 (-A). There are more choices in the Brown/Blackface era that you might consider. There is also the JTM45.

How much do you depend on having a layout. It's a fairly simple mod to add a mid control to most post 59 Fender amps.

[mark enger]

I have a full work shop that rivals anybodys. i have a squaring shear a fingerbrake and can make any chassis i want, i have g10 and turrets and build my own board. i have resistors and capacitors for any build im well stocked in that regard. i also have collected iron for at least 25 build mostly old organ and stereo stuff but it is usable iv built about 13 amps not that everyone has worked LOL i really do need a layout as my sch# reading skills are weak at best, although i do use them for voltages and some thing when i get stuck but no i cant build strictly from a schamatic, i do have woodworking tools but my shops not really set up for it although i can read blueprint as im a machinest by trade, cabnit building just dont appeal to me. but im about to atempt a small run of headbox for some builds im selling off, like i said im looking for ideas for amps a little more complex but still cathiod biased or maybe i just need to break down and learn how a fixed bias works and start building them thanks mark

[tubeswell]

A TW rocket with 6V6s? (but maybe use 470R 3W for each screen grid resistor and 20W 125R cathode resistor - or 2 x 250R 10W in parallel (instead of the 100R 25W), and an OT with a 4k primary Z. Everything else should be about the same.

[mark enger]

that sound cool is there a layout, mark

[tubeswell]

The trainwreck amp schematics and layout info should be at the Amp Garage site.

But I don't know if there is layout or scheme for a 6V6 version per se - that was just me improvising :-) . But it'd be the same as for the EL84 version except with the basic changes that I suggested (I would say).

[loudthud]

I don't know if a TW is what you are looking for. I got the idea you kind of liked the 25W or so cathode biased 6L6 output stage and wanted either a 5F6A or Blackface preamp. Not very hard to do but it might be hard to find an exsisting layout.

How do you feel about tube vs solid state rectifiers? Want to use a choke? Does the 5E5 have enough gain or would you like more overdrive? Do you like the two channel 5E3 inputs or would one channel be ok? Do you object to "bright switches"? There are many possibilities. If all you need is a layout, I can do one in a couple of days.

[mark enger]

that would be great if you could do that if you did i would give you something in return maybe you need a .022 400 sprague bumblebee for your les paul or i could hook you up with some very nice pre 1965 ge 12ax7, or i could even bend you up a chassis if you'de like, the 6v6 cathiod biased sounds like a hell of a amp but what about a jtm45 cathiod biased iv got iron a few do you think they wolg sound good with 450 500v on the plates? thanks mark

[loudthud]

Cathode bias places limits on what a given pair of tubes can do. The 5E3 puts a pair of 6V6s pretty close to the optimum sweet spot. The bias boarders on the class A to class AB crossover point. People here will debate this but I think 6V6s want a B+ somewhere in the 350V to 400V range. (Best at the low end of that range.) For 5881/6L6s the range might be 400V to 450V. (Again best at the low end.) The high end of that range will require 6L6GC. At 500V you are looking at 6550s or KT88s. These amps are best with no or little feedback.

500V on a pair of 6V6s can be done but I think the results will be closer to that EL84 rut you want to stay away from. Cathode bias sounds it's best when the B+ is low. With a tube rectifier, you have options to change the B+ by changing tubes to find what works best for you. Most designs with higher B+ tend towards class AB and fixed bias and the result is higher power than is practical for cathode bias. These designs usually have more feedback in the output stage.

When I suggested the JTM45, I was thinking more of something with published layouts, a chassis with ample room and 5 or 6 pots. The JTM design itself is more of a fixed bias class AB but it has it's merits. It wouldn't take much to modify it to cathode bias. The biggest unknown is finding the right output transformer. There are ways to reduce B+ if the PT has too much.

[mark enger]

thanks i think im gonna have to start fixed bias amps i have to progress heres a amp i just finshed tonight 18 watt tmb , but i want to build all types of amp and start with my own designs after a while im just learning but i hooked bad my hobby self sustaining if no profitable