Diode Clipping 2555SL Help

[elduker]

I have two 2555SL amps.. and both have to sound different of course. One amp rolls off with the typical warmth and thick ballsy sound that it should, and the other well sounds like its built like a solid state no warmth or anything.. so i investigated a little and i noticed between the two.. The two clipping LEDs on one amp illuminate with the same intensity and bleed rate when played through(the GOOD amp).. and the other amp for some reason.. one Led lights a lot brighter and the other dimmer, and the dimmer one bleeds a lot faster? so my question is might this be clipping more signal hence all that? And how might i troubleshoot? Also I have looked everywhere to find out what LEDs marshall used for these amps could someone help me there too?..660nm 635nm 633nm? Thanks guys..

[Enzo]

It is not the color itself, it is the LEDs voltage. The red ones have a lot lower voltage drop than the blue ones for example. Personally, I'd doubt there was enought difference between teh red varieties to matter a lot. But check the data sheet. The higher the drop across a clipping LED, the less ti will clip.

If the LEDs are working different, then I would be checking the LEDs themselves, and also look for any unwanted DC offsets in that area or signal level anomalies that might cause the LEDs to react funny. An open LED for example would not clip its part of the waveform.

[elduker]

Thanks enzo, i checked them out and here's what they read..

(good sounding amp)
1.820 volts LED 3
1.821 volts LED 2


(Other)
1.822 volts LED 3
2.086 volts LED 2

so i took the LED that read 2 volts out and replaced it with a 1.6volt and the same things were happening? To me sounds like something before or after in the circuit like u said? This amp has multiple diodes / led's stacked & assymetrical in the Boost Channel? Anyone experience this anomaly and could anyone give me a little help on how to locate what might be causing that? I'm a novice when it comes to most of this stuff. But i got both amps ready on the bench for diagnosing


Heres a schematic..
http://spradnet.com/jub2555/zimages/2550_ver_2large.jpg