3 tubes, What build?

[Zben3129]

Hello,

I now have 3 tubes, a 12ax7 and 2 EL84's. I also have a pt tranny that measures 12vac or 24vac, and one that measures 50~60vac. I am wondering what would be the simplest/least expensive build with these? I have only standard parts for the 9v boxes

Thanks!

[dschwartz]

hmm let´s see..

if you have a 120V main voltage..
you can put the 120-60V and the 24V-120V back to back, like the mctube configuration..this will give you around 300V AC..and around 420V DC..that sounds pretty good for a B+....even a little high..but you can lower the voltage a little with a 5W series resistor..
You can take yor heater voltage from the 60VAC, but i strongly recommend using a different transformer for that..

You need a lot of different parts to make a tube amp..you can´t use most of the effects parts, get High voltage Caps, fuses. 1/2, 1, 2 and 5 W resistors , a life ensurance.. etc.

since you have only 1 12ax7, only a power amp can be built.. get 1 or 2 extra  12ax7 and you can make a complete amp..

BUT!!! you have to get an output transformer first of all..

good luck

[GibsonGM]

You can make a Marshavalve booster if you add a J201...it's pretty much a booster, and can make a SS amp sound a little more tube-like.  If you back-to-back 2 Marshavalve circuits, you can add a gain control and get pretty dirty with it as an OD  ;o)   Tubes are only like $6 each, so look into getting a few more 12ax7's as mentioned above.    The Marsha is a good way to get into it, and runs on 12V.

[Zben3129]

Thanks guys, may start lookin for an OT today!

[Electric_Death]

since you have only 1 12ax7, only a power amp can be built.. get 1 or 2 extra  12ax7 and you can make a complete amp..

Surely he could build a chip or trani based preamp and utilize the 12ax7 what it's best for, the distortion.....

[Papa_lazerous]

Surely he could build a chip or trani based preamp and utilize the 12ax7 what it's best for, the distortion.....

Exactly.......My Matamp Minimat has only one ECC83 in there but my boost control is just a 4558 driving it harder.  Works nicely

[Zben3129]

Nice! Does this use any trannys or parts I may not have for normal 9v boxes?

Zach

[Papa_lazerous]

you will need a PT an OT high voltage caps some resistors of a higher wattage a chassis and valve sockets at the least

[Zben3129]

Good Info!

Thanks

[distortedskies]

you can build tube amplifier with a few more parts. Forget the 60VAC transformer into a 24V transformer, 420V will be to much for an EL84, and there is no available filament voltage. there are ways to get this lower such as using a choke input filter or zeners in the centertap to drop the voltage but if this is your first shot at a tube amp these might not be as easy to implement. If you really want to build an amp drop a few more bucks and get a PT with a 6.3VAC winding @ 2A or more and something between 200-0-200VAC and 250-0-250VAC @ at least 70mA preferably more like 100mA. If you want to use the pair of EL84's in push pull then get a 5k-8k pp output transformer rated at at least 15W, if you only want to use them in Parallel single ended then you can pick up one of the hammond 125ESE OT's and set it up for a 2.5k primary. If you just want to use one EL84 in SE then get something like 5k at at least 5W. You'll probably want another 12AX7 in the preamp but it is not neccesary, you'll only need to swing about +/- 18V to start overdriving the power stage. If you really want to get into tubes I would recccomend picking up a cheap old mono tube amp on ebay and hack it into a guitar amp. These amps are readily available and usually don't sound to bad with a little work. You can often pick them up for about $50 and then you get all the main components such as the PT, OT, sockets, and chassis. Go to the AX84.com forums and you'll find tons of info on building with tubes.

-Matt at Triode Electronics

[ItZaLLgOOd]

Go to the AX84.com forums and you'll find tons of info on building with tubes.

Check out the P1 or the P1-Extreme from AX84.com.  The projects there have everything you need (schematis, layouts and parts lists) to have a successful build.  I built the P1-EX and I am very happy with it.  It starts to get expensive with transformers and high voltage caps but its worth it.  It's cheaper than buying a tube amp but near as cheap as stompboxes.  I spent about $300 on the complete amp.

The EL84's are power tubes so I don't think that they will do you any good in a stompbox type application.

[drewl]

I'd highly reccommend building a Marshall 18w clone.
One of the best sounding amps ever, sort of a mini bluesbreaker.
I've built a 2x12 combo out of junk parts and a head version from a kit.