el84 amp advice

[trigger]

hello my first post here, planing to build my first point to point tube amp from scrap parts. i gathered some old tube projects for years back to get some parts to harvest, a el84 12au7 amp i pulled from a old record player if i recall correctly, also available i have a tube radio with 2x 505c, 12ax7, and 7 9pin radio tubes.
the el84 amp was given some terminals, input jacks, and a power switch, nothing else was done, all original parts, i don't recall the make or model,(if any one knows please tell me).
i would like to find a project to make using these parts, just a simple amp with a separate simple pre. now the el84 sounds ok now, i just dont like all the control pots. perhaps i could remove the controls? noob here, i know my way around a schematic and iron. perhaps someone could recommend a good beginers project with no to little budget and my parts available?



i have here the pics of the amp, the circled red is the parts i added, the yellow is what id like to remove, if at all possible

[planet10]

Looks like a good candidate for an RH84. Adding a choke would be a good idea, and you'd need a 12AT7 for the front end (you should be able to find a used one cheap). That will leave you with a spare tube socket to add another gain stage (pre-amp) if needed (my RH84 don't need).

dave

[Brisso57]

Originally Posted by planet10

Looks like a good candidate for an RH84. Adding a choke would be a good idea, and you'd need a 12AT7 for the front end (you should be able to find a used one cheap). That will leave you with a spare tube socket to add another gain stage (pre-amp) if needed (my RH84 don't need).

dave

The second RH84 amp pictured appears to use SS rectification?
Details??

Thanks

Doug

[planet10]

Both use Greatz bridges, half vacuum (EZ81), half-SS. The second set of amps are monobloks and a fairly dramatic variation on the RH84. The front-end is triode strapped EF86, and the 2nd OPT is used as a plate load for a parafeed output stage.

dave

[trigger]

thank you for the advice, the rh84 looks to be my first project.
i live in the boondocks, and headed to the nearest city today, passing the only place i would ever see a tube(thrift store), i decited to go in to have a look, and to my surprise there was one and only one tube radio there, i picked it up and to my surprise it uses 12at7 tubes!!! what the luck of a drawl seriously this thrift store rarely ever has tube equipment and when it dose its usually overpriced organs.
so i picked up a untested pair of 12at7 along with a snazzy eric fm radio, for 10$

thus i shall start the rh84,,my first question is about the choke, where could i find one? like to salvage, is there any electronic devices with i suitable one i could pull.

there is a junk yard near by, i went and pulled all the tubes and speakers but still lots of transformers, there are council radios, ic and tube, tube tvs, lots of old junk. i bet somewhere in the mess i bet is a good choke for my project, but (excuse my noviceness) what the heck am i searching for? its a transformer but how can i tell what one i need? gather all them up bring them home and testing them would be a nightmare unless i had some precious knowlege that would lead me to a 5k ot? anything?

[planet10]

Most of us, i expect, buy our chokes on-line. If you can find one in your junk box, just make sure it is at least 100mA.

If you have to buy one you'll want something like a Hammond 158M 10H 100mA. They are about $20 (+ postage). You can build it with a power resistor to start, but the choke is a simple way to really improve the PS.

dave

[trigger]

i need to do some studying up on audio transformers, any recommendations on some free online literature on transformers that would help me get a grasp on how they work in the tube amp circuitry?

thank you much for the advice

[trigger]

at least for now i am confused how i can test a transformer for resistance to determine witch i need.