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r/tubeamprepair

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▲ 13 r/tubeamprepair+1 crossposts

In a local street market, I've stumbled across this old radio listed at 25 dollars, and here this thing even without any of its guts is around 50 only for decoration purposes. My father saw it and wants to make an amplifier out of it, I know a little about electronics but never worked with valves before, from what I understand if everything is working I should be able to connect a jack to the volume knob and not much more. I must say when I opened it, I was kind of scared. I don't know what's the procedure for something like this and. Please, if anyone knows what to do with it (even if the most efficient thing is take it apart completely and re make the circuit) or just leave it as decoration. English is not my first language so if you don't understand anything just tell me! Thanks.

u/g203_ — 11 days ago
▲ 7 r/tubeamprepair+2 crossposts

I have inherited a 1966 Silvertone 1484 Twin-Twelve that works but is in pretty bad condition, and I've decided to fix it up. For various reasons, I've decided to make nice walnut cabinets to house the chassis and speaker cab, and convert the hard-wired tether between head and cabinet to a regular output jack.

I think I have the basic soldering skill necessary to install the output jack in the chassis and an input jack in the new cabinet I'm building, but that's as far as I'd push my soldering/wiring expertise. I would not feel comfortable converting it to a grounded 3-wire power cord and modifying it to use the new ground wire. I would absolutely not feel comfortable replacing resistors or capacitors.

Am I being an idiot thinking it's okay to do the output jack conversion but no other electronics upgrades/repairs? I think I may have a professional amp tech recap it and do the ground conversion in the future but I really want to get the amount I've already bitten off accomplished first.

Before anyone asks, I never intend to sell it, so ruining its resale value is not a concern.

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u/dickskittlez — 9 days ago
▲ 8 r/tubeamprepair

TLDR: Is this a "death cap" and shouldn't it be removed by taking the Ground switch out of circuit?

I have my father's 63 Fender Bandmaster which he had restored about 5-10 years ago.

He passed and I just received it recently. It played fine for a couple weeks and was giving some really nice distortion with the volume around 8.5 but then it blew a fuse. I think I remember him saying that it blew a fuse for him after restoration so I've got the chassis out and I'm starting to evaluate what's been done to it.

I'm a vintage radio guy and have restored a few tube radios including a '37 Philco so I'm not a total noob but not an expert by any means.

Anyway, the first thing that stood out to me was the two prong cord replacement. There's a .047 cap between chassis ground (green) and hot (black).

Isn't this dangerous for no reason? I'm thinking I should bypass the Ground switch completely, move hot to the fuse tip, and neutral to the power switch.

Any advice would be greatly appreciated.

u/Substantial-Plum-260 — 8 days ago
▲ 3 r/tubeamprepair

I have a fixed bias push pull output stage in an amplifier, it has 2 6P3S-E's (6L6). Plate voltage is 324. I have a 1ohm resistor between the cathodes and ground. I've measured the voltage drop across the 1ohm resistor and get a result of 0.252v.

My understanding is that this reading should translate to the same number in ma.

I understand I need to multiply the plate voltage by the 0.252ma.

324 x .252 = 81.64

Do I need to do anything with that result or does that mean my tubes are dissipating 81w? 🤔 and if so, is that averaged out between both tubes?

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u/Due-Charity2393 — 12 days ago
▲ 8 r/tubeamprepair

Anyone got any idea what these resistor values are on a Bogner Uberschall 6L6 rev blue version?

(Slots R417 & R418)

….pretty sure a power tube went bad & is what fried my heat resistors next to the amp fuses.

u/LoadedYouth — 11 days ago
▲ 11 r/tubeamprepair+1 crossposts

I want to add (DIY or Tech) a Power Amp In to a Tweed Champ 5f1 style amp for use with something like the Tone King Imperial Preamp.

Is it really this simple? I

u/gotoyourhomeball — 13 days ago
▲ 5 r/tubeamprepair

Hi everyone,

Recently, I started seriously playing guitar again and fulfilled a teenage dream by buying a Bogner Uberschall.

Since this is my first tube amp, I noticed that it produces a sort of mechanical vibration when I play at certain volume levels. The vibration decreases as I lower the volume.

I can’t clearly tell whether the sound comes from the second power tube from the left, or from the output transformer located just behind it.

The video shows a quick test with the amp connected to a Two Notes Torpedo Captor X (the fan noise comes from the Captor X).

I gently tapped each tube with a pencil while the amp was running, but I couldn’t hear any obvious ringing or microphonic resonance at the output.

My questions are:

  1. Does this sound like normal behavior for a high-gain tube amp?
  2. If not, what would you recommend as a first troubleshooting step?

Thanks for any help!

PS: For context, I’m a hardware engineer, and of course regarding electronics safety, I apply the exact same precautions and high-voltage safety practices that I follow in my professional work.

u/Stack_Solo_43 — 6 days ago
▲ 5 r/tubeamprepair

Isolation transformer recommendations for guitar tube amp work?

I work mainly on vintage tube radios and guitar amps. I recently got an oscilloscope for my bench. I understand that in order to protect the oscilloscope, it should be plugged into an isolation transformer. I am searching for an appropriate isolation transformer, but so far I've had no luck. It seems like on all the products that I look at on Amazon or other supply sites, someone comments that that product is not truly isolated and that you need to make a mod to it. I'd prefer to buy something that I don't have to mod. Anyone have any recommendations for me?

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u/FriendlyBuffaloSky — 3 days ago