The Amp Garage

if there is a scope, then is easy..

1. remove NFB wire
2. put 100mV signal on the input
3. trace to the output tubes pin 5

blind shot..i suspect there is no gnd wire on some tubes, missing

So my questions are: That original wiring of the speaker jack, grounded with the bias pot, is that correct, or is it a design flaw from the manufacturer?? yes If so, this makes me question the rest of the grounding scheme in this amp, so I'll then have to take a deeper look at the rest. Could you p...

last 2 days update on the OD sound and tweaks..while clean is correct, OD wasnt so.. i have found OD sound too fuzzy for my taste, not amusing in any way... on the lower register.. tweak to cure that - both OD potentiometers changed from 100k to 250k..(actually they are like that in 183 schematic, n...

i have put mixed NOS and modern , for output Philips Miniwatt brown base EL34

Amp tested clean very very nice, drive under testing, tranformers are good! Nothing too much, normal attack, normal bass , normal treble

mounted transformers on experimental chassis..

i saw.. i saw..

busy last week in winding small 14VAC transformer for DC heaters of V1-V2 and relay switching.. Carsbro PT doesnt have this option... now baked under the sun few h, black paint on laminations, vintage brown presspan on the bobbin,

rootz wrote: ↑Tue Apr 23, 2024 2:13 pm That looks like a nice score! Are those transformers anywhere comparable to something you'd find in a JCM800 2204 of the same age?

sorry for late reply.. 3.6kaa is anode impedance (to 3.5, 7.5, 16 ohms) so it is passing to JMP amps yes manufacturer is the same, so looks all good

some beginner amp with not correct layout..(builder didnt have idea when building, how the amp will finish seen from many wires passages from left to right ), value 1/10 only for the speaker

from first look pcb up, all the thin traces must be at least double size.. it is temperature in amp, bigger size grips more, C1 C2 are ok.. others i will check tommorow

here i put carsbro pcb where you can get idea of clearance and ground traces

value = 1/10 only for the speaker, maybe transformers too (1.5/10) all the rest in the garbage bin

been there..add one small triode in front of PI, or small pentode triode connected.. you will miss some volume otherwise if run only from multi-effects board

bepone - understood, but I’d rather stick with the SS rectifier for this I think. Seems truer to the circuit. BTW - Really enjoyed reading about your 183 derivatives. Very informative to follow your process with these. thanks, will be update in the theme soon, mounting vintage Carsbro transformers ...