New Years resolution: learn to build/modify a tube amp

[dayn]

After lurking forever, I need to jump in and build something!

I will do some reading so I can understand parts/lingo, and acquire some tools, but here is what I want to modify:

[img:640:425]http://i141.photobucket.com/albums/r69/ ... besMTI.jpg[/img]

[img:400:300]http://i141.photobucket.com/albums/r69/ ... Tubes1.jpg[/img]

[img:640:428]http://i141.photobucket.com/albums/r69/ ... s2_sch.gif[/img]

[img:400:267]http://i141.photobucket.com/albums/r69/ ... es_sch.gif[/img]

[img:400:300]http://i141.photobucket.com/albums/r69/ ... Tubes2.jpg[/img]

I would love to turn this little guy into an actual amp head, which I would think means I need to get rid of the built in load, headphones out, etc. and have speaker outs.

Any ideas?

[xtian]

That 2" speaker in there is rated at 8ohms (according to the schem) so just run those wires out to your cab to test it. It's not going to be very loud, though.

[NEjoe]

Does he have a 230V supply? The schematic shows a 230V input.

Is that 5 volts going to the heater supply? Don't 7025s want 6.3V?

By "modify" do you mean change the power transformer, output transformer and....uhhhhh......gut mostly......everything in between?

In other words, keep the chassis and replace the internals with a two tube champ-like design? I think there isn't much space in that chassis for much more.

Maybe starting from scratch or a kit might be a better jumping off point......

Wow, reading that back it sounds really negative.........but I'm just not seeing much of anything to keep.

[rhinson]

Does he have a 230V supply? The schematic shows a 230V input.

Is that 5 volts going to the heater supply? Don't 7025s want 6.3V?

By "modify" do you mean change the power transformer, output transformer and....uhhhhh......gut mostly......everything in between?

In other words, keep the chassis and replace the internals with a two tube champ-like design? I think there isn't much space in that chassis for much more.

Maybe starting from scratch or a kit might be a better jumping off point......

Wow, reading that back it sounds really negative.........but I'm just not seeing much of anything to keep.

from the look of the schematic, the power trannie may have a dual pri wired in series (can't tell from the actual pics), in which case you can just rewire it parallel to run at 115v. rh

[daydreamer]

That thing looks cool, Keep that as it is and build a stand alone power amp....that way your controls are front of stage with you speaker cab and power amp on the backline...

Nice and simple, SE with a master volume and nothing else control wise. I've often wanted to have the amp controls close by without wandering around stage.

[dayn]

In its current state it is a tube preamp pedal of sorts. Actually a single ended amp with output transformer into a resistive load with a switcheable reactive load (the 2" speaker), then to the output jack or headphones. A low-wattage amp to slave some power tube distortion into another larger amp.

I am wondering if I can get rid of the loads/headphone option and just have speaker outputs. Then maybe tweak the circuit to achieve more optimum sound if needed.

Seems possible to me but I don't know how to pull it off technically.

[Cliff Schecht]

It'd be easy to setup the box so that if you plugged in an external speaker, it would disable all of the other onboard stuff you don't want. You just need a mono shorting jack that when a speaker is plugged in, the connection to the dummy load, 2" speaker and headphone out.