This has been a project I've been threatening to do for years! Almost complete, it finally works.
I had a month's long setback when I destroyed a perfectly good vintage KILLER power transformer with a dead short at the rectifier socket. A ground tab on the octal socket was touching one of the plates, out of sight, and the fuse (naturally) didn't blow.
Ordered a replacement (different planform
), so doesn't perfectly fit the chassis, but it works!I ran DC for the 12AX7s and needed to add a small cap to ground to get rid of all hum! Imagine that, a vintage tube guitar amp without hum!
At the suggestions of musicians (who know stuff!), I built a replica of a Marshall Plexi series JTM45. Used a reproduction chassis and faceplate, built a case, and tried to stick with as much correct as possible. Obviously, the iron is not correct.
The larger output and power transformers mean that he can run any of the common output tubes: EL34, KT66, KT77, KT88, KT90, KT120, 6550, 6L6GC, etc. I'm supplying a printed list of bias set points for any of the tubes.
The bias check points that I added are across 1 ohm resistors, so checking and converting is easy: 50mV = 50mA.
For speakers, a kind friend donated an empty open back case, into which I added a pair of Celestion G12 Vintage drivers (on sale at PE).
Only stuff remaining is to cover the front plate with Tolex, add printed labels for the tubes, make the lad an owner's manual (few words, pretty pictures, (ADHD!), and get a couple of logos made for the front panel of the case and the speaker enclosure. I'm thinking "POLANSKY" in a script similar to the famous Marshall script.
Little bugger better like it and use it. I built my little brother a stereo: speakers, amplifier and turntable (made the plinth). He sold it for drugs!
| Attachments: |
|
Drivers.jpg [ 548.28 KiB | Viewed 32024 times ] |
|
Side.jpg [ 539.43 KiB | Viewed 32024 times ] |
|
Front-amp-case.jpg [ 864.36 KiB | Viewed 32024 times ] |