Hi there,
I have a VOX escort Lead 50, one of the companies first transistor amps.
After testing loads of the electrolytics were bad, so I went ahead and replaced them all, as it was cheap and easy. The amp is now super silent but the tone is odd (it was odd before the re cap), and I can't believe it was like it from the factory, but maybe these are just crappy odd sounding amps.. if so I'd love someone who knows to tell me its just a bit of a junky amp!
Failing that, here are the problems - The low input is super bassy, unusable unless you put the eq to full treble ish. The high input is super bright, crazy bright really. The input resistors are 100k rather than the 68k on the schematic, though I ONLY can find the schematic for the escort Bass 50 (not the lead). My amp looks real similar in general to the bass version, so I'm wondering if those 100k resistors should really be 68k (as per the bass version's schematic, and the usual value).
Additionally, there is a RC4136DB IC providing quad amplification for bits of the eq circuit and on the input, and some of the transistors are 3055's which I'm led to believe are quite low performing...
I'm looking for either test advice, or experience with this amp those with or similar components as with where to start. All the transistors and the IC amp are pretty cheap, I could re-do them all for £30 ish, though I'm open to anyone saying that's silly and not that likely to help. I'm a bit stuck though, I know where I'm at with valves more or less but this is a bit of a puzzle. Especially as the only schematic I can find has a couple of different controls (no vol. / master vol. on the schematic, the master vol is replaced with a 'harmonics' knob, and the related circuitry is not in my amp as far as I can see...
Thanks for any help offered!
EDIT- I have had the PCB off the chassis and fixed any VISIBLE dry joints, but cool to go in again and do the whole thing if people think its most likely that, similarily I haven't rigorously tested all the resistors for drifting etc.. cool to do that if that's more likely than the transistors.
I have a VOX escort Lead 50, one of the companies first transistor amps.
After testing loads of the electrolytics were bad, so I went ahead and replaced them all, as it was cheap and easy. The amp is now super silent but the tone is odd (it was odd before the re cap), and I can't believe it was like it from the factory, but maybe these are just crappy odd sounding amps.. if so I'd love someone who knows to tell me its just a bit of a junky amp!
Failing that, here are the problems - The low input is super bassy, unusable unless you put the eq to full treble ish. The high input is super bright, crazy bright really. The input resistors are 100k rather than the 68k on the schematic, though I ONLY can find the schematic for the escort Bass 50 (not the lead). My amp looks real similar in general to the bass version, so I'm wondering if those 100k resistors should really be 68k (as per the bass version's schematic, and the usual value).
Additionally, there is a RC4136DB IC providing quad amplification for bits of the eq circuit and on the input, and some of the transistors are 3055's which I'm led to believe are quite low performing...
I'm looking for either test advice, or experience with this amp those with or similar components as with where to start. All the transistors and the IC amp are pretty cheap, I could re-do them all for £30 ish, though I'm open to anyone saying that's silly and not that likely to help. I'm a bit stuck though, I know where I'm at with valves more or less but this is a bit of a puzzle. Especially as the only schematic I can find has a couple of different controls (no vol. / master vol. on the schematic, the master vol is replaced with a 'harmonics' knob, and the related circuitry is not in my amp as far as I can see...
Thanks for any help offered!
EDIT- I have had the PCB off the chassis and fixed any VISIBLE dry joints, but cool to go in again and do the whole thing if people think its most likely that, similarily I haven't rigorously tested all the resistors for drifting etc.. cool to do that if that's more likely than the transistors.
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