Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Ryan22 on November 11, 2024, 10:24:10 pm
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I picked up a late 50s Motorola console record player the other day and I’m curious about the possibility of converting the phono tube amp into a guitar amp. I purchased it mainly because of the Jensen P15R speaker and the choice of tubes seemed to have potential for a conversion. Admittedly I know very little about this stuff other than restoring my 66 Ampeg Gemini II. I may just restore it and use it in a hifi setup as intended but I’m interested to know if you guys think the circuit would be a worthy project for a guitar amp. Hopefully attach the schematic correctly
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once it works, plug in to an AUX jack and jam, maybe use a guitar speaker, then you'll know
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I haven’t pulled the chassis yet but the previous owner had it running when I picked it up. It will obviously need a recap. Tubes are original. With the little research I’ve done it seems that a modified version of the stock circuit is common practice when converting these types of amps. Not always but I’m wondering if this amp would be a good platform for such mods based on the schematic. The P15R is a lower wattage version of the P15N which was used in many guitar amps. The Jupiter speaker in my Ampeg is a P15N clone
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It looks to me you have the bones to build a Fender Deluxe 5E3. By bones I mean transformers, tubes sockets, terminal strips, chassis and rectifier. From my experience in rebuilding hi-fi amps for guitar, the existing tone stack usually will not work well. Also all the hi fi wiring and controls are pretty useless for guitar purposes.
So what I've done in the past is gut the amp of all the unusable hi fi circuitry, leave all the good bones mentioned above and rebuild the amp to a known good circuit like the 5E3 or some other known 6V6 Push/pull guitar circuit.
Shooter is right as to get what you got working first, then modify it for your guitar purposes from there. Main thing prove the power and output transformers are working
which are the most expensive parts to replace in the amp
Last but not least, if your going to get into tube amp building, learn how to make a schematic at the same time