Amplifier Modification

[flood]

I'm sorry, but I have to chime in here. I'm really not trying to be either rude or mean, but I have to say this. If you felt like it was reasonable to ask if you could mod a 15W amp to 100W or 200W, you have no business (at this point) building or modifying anything with tubes. Vacuum tube amps run with some potentials over 350V DC which can and will kill you if you do the wrong thing.

If you want to learn more about electronics and learn (and get to be in the habit of) safe building practices and then start on tubes, go ahead - but jumping in without any background is very, very dangerous.

he's absolutely right. nothing like a nice capacitor discharge to make you rethink tube projects for the next couple of years.

i would seriously advise you to start by building stompboxes and moving upwards from there, understanding amps step by step. and IMHO it's not worth investing so much time and money into a behringer 15W combo - there are better, mod worthier amps there. but save that for later. even the firefly with it's 0.5W output operates on potentially lethal voltages!

good luck, and most of all have fun learning...!

[Drak]

Easy answer here:

Dude, you live in Canada. Go find yourself a Traynor YBA-1 head, it's pretty much tear your house down loud at 50W.

You should be able to find someone looking to get rid of one for cheap up in those parts.

AND it's already in head form, so it will fit on your cab, no need to make it harder than it need be.

Great tube amps for the money, especially up in Canada, which is where they were made.

Hell, most of the Traynors I've bought over the past 10 years (about 8-9) CAME from Canada, they're all over the place up there, and Traynors (with a few basic mods and $20.00) are very much like old Marshalls.

You should like that.

And don't hurt yourself.

[mikhailgtrski]

Eats Traynors for breakfast. Marshalls for lunch.

(just kidding) :D

[ansil]

to shift this over slighty from vavles what fwould you do to increase the volume out of a solidstate line 6 spider amp with 100w - 2-12' 8ohm tubetone speakers with LM3886TF amp chip finals????

if you got the juice to run it you can double up the chip.

[BigG1986]

to shift this over slighty from vavles what fwould you do to increase the volume out of a solidstate line 6 spider amp with 100w - 2-12' 8ohm tubetone speakers with LM3886TF amp chip finals????

if you got the juice to run it you can double up the chip.

would the chip handle that?? and how would i do it??

[ansil]

to shift this over slighty from vavles what fwould you do to increase the volume out of a solidstate line 6 spider amp with 100w - 2-12' 8ohm tubetone speakers with LM3886TF amp chip finals????

if you got the juice to run it you can double up the chip.

would the chip handle that?? and how would i do it??

realize this has been sometime ago but completely forgot to say i had been buying little practice amps that had the lm1875 in it. and i would recreate the same output stage they had and apply it to a negative input and bridge the output of theamps together. keep in mind though i had to put in an extra voltage tranny. but it works like a champ

[ToddW]

If you are considering building a tube amp, the beginner projects at AX84 are all good ones. There is also one that I built that is called "Octal Fatness", and it's a GREAT sounding little single-ended amp that puts out about 5-7 watts depending on what power tube you use. I also built the Firefly, which is about 1/2 to 3/4 watts using a self-split 12AU7 as the driver tube. It gets pretty loud for such low wattage. And it's now an official AX84 project, too.

Here's my Octal Fatness page: http://www.diyguitarist.com/GuitarAmps/OctalFatness.htm

And my Firefly page: http://www.diyguitarist.com/GuitarAmps/FireFly.htm

Hey Paul,

I've actually got the PSB for a firefly sitting in my closet, and I'm waiting for Mike (Komboking) to finish a chassis for me. Not for the firefly, I'll just get the hammond chassis for that, but Mike is making me one for a CA Dreamer type build.

Chibi,

Turning the 15 watter into a 200 watt tube amp sounds easy to me. Just rip out the entire output section of the amp but keep the phase splitter. Then all you need is another power transformer, a rectifier, a few large capacitors to filter the supply, two to eight tube sockets and some tubes, a few dozen resistors and capacitors, some 20g wire, a soldering iron, a bunch of turret board or circuit cards material, and an output transformer capable of handling 200 watts. Hammond's 1650W is only $195 plus shipping. I doubt it weights much more than 15 or 20 pounds and it's canadian!

That stuff won't set you back more than a four or five hundred dollars, assuming you don't wire it wrong and destroy the OT.

You'll need two power supplies because you don't want to fry the pre-amp section of this little amp. I'm assuming we don't care about this thing being quiet, so I didn't list a choke or mention that you may need to figure out if there's a feedback loop. I'm assuming the splitter in your little amp is sufficient to drive the new output section. Hmmm, I guess I did forget to add it the price of the tubes.

Oh yeah, you're going to need to drill a lot of holes in the cab and maybe add a fan to stop it from catching fire since we're putting such big bottles in it. But just think how HOT it's going to be

I guess I just don't understand what the problem is guys?

Todd

PS) Just messing with you, Chibi. Kevin O'Connor has a design in TUT 5 for the Super Scaler, which takes the output of a little amp and makes it bigger. I think the listed design would get you to 80 watts or so. He also has plans there for the "Stentorian", which is around 150 watts. May be voiced for bass, but that's an easy thing to tweak. Those are not beginner projects, so the bottom line is, if you want clean tone and more volume, , you're going to want to buy a bigger amp. But 200W is just too HUGE. It'd destroy your speakers. If you have 4 x 50W cones, stick with 100W or less!

[psw]

People do realize that this thread dates back to 2006 and the original poster has not been around for a long time?!!

The original answers really were the most sane...the poster wanted to turn a cheap Behringer 15 watt practice amp into a 200 watt monster...really a very silly idea!

Even the more recent (jan 2007) post involving solid state amps...very strange idea and possibly not the kind of thing that novices should attempt.

If you love the sound of these cheap little practice amps that much and you really think you need that kind of wattage (which is kind of unlikely given the volume of a good 40 watter for instance), get a clean amp and use the practice amp as a slave...but really it is a bit silly with a behringer and messing with amps can be very dangerous. Even if successful, the mods can come back to bite you through a bad solder join or failed component (likely with the increased power loads) and kill you, or the poor unsuspecting buyer it may one day pass on to...like a time bomb!

Nice to see you back though ansil...

pete

[ToddW]

ROFLMAO . . . nope, didn't realized that.

Thanks for the heads up