Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Mike_J on August 10, 2019, 04:34:07 pm
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I am rebuilding my 5E3 which uses the Hoffman 5E3 layout. Have a question concerning grid wires from the tone control to V2-2 and the the two wires from the pi to the power tube grids. I ran the wires using shielded wires before. Wondering if this is necessary. Also planning on running two 100 ohm resistors from the cathode resistor/cap junction to run heaters on top of DC. Any experience with these matters would be appreciated.
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I didn't use any im my 5Y3 and I wouldn't use any in Hoffman's layout either.
I've elevated heaters to output tube cathodes in a couple amps. Couldn't hear any difference from referencing to chassis ground.
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I didn't use any im my 5Y3 and I wouldn't use any in Hoffman's layout either.I've elevated heaters to output tube cathodes in a couple amps. Couldn't hear any difference from referencing to chassis ground.
+1 On the above - 5E3 with good lead dress requires no sheilded wire. . For what reason are you "rebuilding" it?
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I ordered transformers that fit a deluxe reverb for the original build. My 5E3 had more headroom than it should have so I blamed it on the transformers. Made a deluxe reverb with the transformers and am very pleased with the sound. Classic Tone had a sale on a PT for the amp with a B+ winding of 330-0-330 instead of the 355-0-355 so I ordered transformers.
When I originally built the 5E3 I used cloth covered wire, Allen Bradley carbon comp resistors, the aforementioned shielded wire and some caps for V2 that were much larger than necessary. The chassis is way too cramped for anything more than is needed in my opinion. I also put a choke in the amp which may have contributed to the headroom. The original amp sounded good and was quiet but not what I wanted it to be.
I am putting Rob Rob's lead channel in the normal channel and am looking forward to hearing it.
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Thank you for the responses regarding not needing shielded wire.
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When I first started building amps I started with a Fender four-hole tweed bassman style amp. Thought it was crucial to use Allen Bradley CC resistors, tried to get my hands on as many or the blue molded Ajax caps that were used in the Fender blackface amps for use in my amps, used cloth covered wire, etc.
Having built ten different styles of amps I now tend to try to make as much space between components as possible so smaller caps are used. The CC resistors do apply more hiss than metal film resistors do. Metal film resistors are also smaller so I can use higher wattage resistors which I believe also helps a little with the noise. The cloth covered wire is not as easy to use as the teflon coated wire is so I switched to teflon. I like the small capacitors Hoffman sells. They accomplish the space issue and sound just fine.
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The cloth covered wire is not as easy to use as the teflon coated wire is so I switched to teflon.
Really? You must have used that stuff with cloth outer jacket and pvc inner jacket. Hoffman sells the good cloth wire. Just cut to length, push back the insulation to expose the wire, make connection, and finally push the insulation back in place. It's the easiest and fastest way to make a connection.
I still prefer stranded Teflon even though it requires much more work to make a nice connection.
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I bought the cloth wire many years ago and the coating under the cloth melted if it got anywhere near a soldering iron. Very easy to burn it up if not very careful. The style of cloth covered wire Hoffman is selling is vastly superior to the wire I was using.
I think I read years ago that cloth covered wire was used because it was quieter although I have not heard my teflon wire bouncing around inside the chassis and making noise and I have enough of it so that is what I use.
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it did not have the coating under the cloth melted if it got anywhere near a soldering iron.
What melted...? If you're talking about the cloth burned, you didn't push it back far enough. IMO, cloth "push back wire" is the easiest and fastest to use, Teflon is much harder to strip unless you have expensive strippers but it's probably the best wire you can use.
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> What melted...?
There's cloth, plastic, and cloth covered plastic. He got the cloth over plastic. Cheap plastic. Not good stuff.
True cloth push-back is the bees-knees for rapid wiring.
Teflon or treated PVC is good around solder.
Cheap PVC is like wax. One of the Big Distributors has a lot of cloth-covered cheap-PVC.
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It was the pvc. Melted very easily. It is coming out of my amp. Must have decent strippers because I never have trouble with the teflon wire.