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
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
Attachments
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
dave
SS rectification?
The second RH84 amp pictured appears to use SS rectification?
Details??
Thanks
Doug
The second RH84 amp pictured appears to use SS rectification?
Details??
Thanks
Doug
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
dave
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?
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?
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
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
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
thank you much for the advice
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