Newbie= tube amp build in the right direction?

[D28]

Hi all,
I'm considering a venture into the tube amp world of building, I have very limited experience and knowledge in this area. I'm looking for an avenue that would be fairly easy in the electrical detail side, maybe just plug and play type application. The cabinet build is where I would have my fun.

I've got myself an old telephone amp that seems fairly complete, it powers up and creates a loud buzz to the 4" speaker. It appears all original.

The info tag reads
Cycles 50/60
Volts 117
Amps .25
Watts 20

Ive got a vibro champ that is 5 watts that really cranks, wouldnt the 20 watt be comparable if not more? Or is that a wattage misconception that amps sometime do?

There are two input connectors on the back that seem incapacitated no matter what I do to them.

Here are my concerns:
Is this even feasible with this amp? if so:
Are these tubes consistent with what I would need?
Is the wiring schematic set up in a way that would work without none to minor renovation?

I would appreciate any input concerning this with what I have. I do have an electrical tester too.
Here are some photos:

[IMG:640:480]http://i59.tinypic.com/2hwk9i1.jpg[/img]
[IMG:480:640]http://i58.tinypic.com/2mwfjir.jpg[/img]
[IMG:480:640]http://i62.tinypic.com/2cz3o6d.jpg[/img]
[IMG:640:480]http://i61.tinypic.com/2eqch84.jpg[/img]

[ToneMerc]

The 20 watts of power is it's consumption, not audio output. There's most likely a degree of impedence mismatching as well. Telephones are low impedence devices whereas, magnetic guitar pickups are high impedence devices. These devices where some of the first attempts of a speaker phone.

IHMO, there are more suitable donor amplifiers to use a guitar amp.


TM

[billc]

That appears to be a series filament amp with NO isolation from the AC power in....if so do not fool with it until an isolation transformer and three prong cord are added, as is series filament amps are dangerous and if a guitar is plugged in can put 120V on the strings...that could be very painful or even fatal. You could add an isolation transformer but IMHO would be much better off buying a $25 reverb unit xfmr, wiring a solid state rectifier, then building a two tube Champ like maybe a 5C1 on that chassis. I have two similar Western Electric amps. For some more on the safety issues with series filament gear see http://en.wikipedia.org/wiki/All_American_Five

[img:980:748]https://lh5.googleusercontent.com/-gKNg ... 0l6se3.JPG[/img]

[gui_tarzan]

^ this

Also, my suggestion would be to look over the sticky threads here for information regarding safety working on these amps. You may already know this but there are hundreds of volts at several points in these amps and that can kill you.

That's not to dissuade you, just pointing it out so we don't read your obituary in the paper. There are several websites that are referenced here that have more information than you can imagine about how and why amps work like they do. Start there. I've been working with tube amps for a long time and I'm surprised at what I didn't know about the theory end of it, which is essential for troubleshooting and designing.

Keep your eyes open for things like old PA or intercom amps at swap meets, they're just begging to be turned into guitar amps and can be had for cheap.

[Jerryz1963]

I have picked up many amps out of tube type organs for cheap and they are excellent for conversion to guitar/musical instrument or stereo. The power transformers tend to be overkill for the application, they sometimes offer 2 choices for B+, 5, 6, and 12-volt heaters. the ones I have gotten were usually better quality than the average hi-fi tube amp. There will be plenty of tube sockets to play with and there is plenty of room to work under the hood. I think you would find it a very low frustration frustrating way to get started.
I like the Conn organ ones myself,

[rdjones]

I have picked up many amps out of tube type organs for cheap and they are excellent for conversion to guitar/musical instrument or stereo. The power transformers tend to be overkill for the application, they sometimes offer 2 choices for B+, 5, 6, and 12-volt heaters. the ones I have gotten were usually better quality than the average hi-fi tube amp. There will be plenty of tube sockets to play with and there is plenty of room to work under the hood. I think you would find it a very low frustration frustrating way to get started.
I like the Conn organ ones myself,

Conn, Thomas and of course the ubiquitous Hammonds are good sources for 'organ donors'.
Transformers, tubes and even caps.

rd

[D28]

Looks like this isn't the right catalyst, thanks!

[Jerryz1963]

If you watch c/l, often times people give away or practically give away those old organs that have been kicking around in grandma's basement. Oftentimes they (the owner) don't know a tube from a transistor. If you are near a big city, odds are you won't have to wait long and one will show up. Seattle C/L has them with surprising frequency. They won't necessarily list them under musical instruments. You will usually START with a working amp and that makes it easier for the newb.

Good luck!

[billc]

Looks like this isn't the right catalyst, thanks!

Not as is, but you could probably reuse the OT, buy a reverb unit PT plus a 6SJ7 and a 6V6 and build a 5C1 Champ for not too many $$$. The organ amps make great guitar amps as was said and I have two in the pipeline but they are not a good choice for a first build, better to complete something much simpler first...like this


[img:400:331]http://prowessamplifiers.com/schematics ... ematic.gif[/img]

[Jerryz1963]

If budgetary constraints are an issue, I have a cool secret for you.

There are, in many cases, 12-volt heater versions of great tubes. The 6V6 for example, is available as the 12V6. EXACT same tube, just takes a different heater voltage. Same with the 6SJ7. Look for the 12SJ7. Saves you money. Plus a BIG plus IMO, you can use 12 VDC for the heaters and kill a major source of power supply hum, no small consideration in an SE application.

I have many black plate 12V6 tubes, many of them test as new or better. I picked 'em up for cheap. Even Tube Depot sells the 12-volt heater versions. The vast majority don't even think to look for 12-volt heater versions of their favorite tubes and will shell out big bucks for precisely the same tube in 6-volt heater version.

I had a power transformer that didn't have the 12-volt heater output, so I bought a Rat shack transformer, got one of their big 5-dollar bridges, and wired up 12 VDC heaters. I do this as a matter of course on all my builds.