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Old 3rd January 2009, 12:43 AM   #1
dubdub is offline dubdub  United Kingdom
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Default simple SE- almost there but right channel prob

Hi

Im almost there with my Simple SE but I am having a problem with the right channel- from the speaker it emits a high frequency ring that can be heard when you put your ear to it the speaker and it is not as loud as the left speaker-it's not there when I dont have an ipod/cd player connected. Ive been having few problems with this channel-at one point it caused my el34 to 'pulse' a red cherry glow which cant be good. After checking and tidying the wires, it's stopped this and sound can be heard-but no as loud as the left channel.

Any thoughts on where I can look to sort the problem out? Any advice would be appreciated!

BTW it sounds great-I put an obbligato 70uf cap and it is very smooth in UL mode with feedback (have not tried tirode with out feedback yet)
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Old 4th January 2009, 10:02 PM   #2
dubdub is offline dubdub  United Kingdom
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well- I found the source of the problem...my ipod! the cd player works fine but my ipod's right channel has given up the ghost-time tp get a new one methinks

When I swap over the valves (jj El34) from 1 channel to the other, one valve will glow red -but they are fine when they are in the positions they are in now-is this due to unmatched valves?

The amp is playing fine and sounding good! Pictures to follow soon in the photo gallery section/thread
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Old 4th January 2009, 10:34 PM   #3
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The ringing sound and the pulsing red plates suggests to me that one channel is oscillating...
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Old 9th January 2009, 01:17 AM   #4
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Quote:
Originally posted by dubdub
When I swap over the valves (jj El34) from 1 channel to the other, one valve will glow red -but they are fine when they are in the positions they are in now-is this due to unmatched valves
Glowing red plates are never a good thing. The design of the Simple SE is such that matched tubes are not necessary. Each tube individually self-biases due to the cathode resistor (R17/R27) on each output tube.

If the tubes appear to work fine when they are installed one way, but glow red when you trade their places, something is wrong. I'd carefully check the cathode resistors on the output tubes (R17/R27) and check the grid resistors too (R15/R25).

Carefully check your wiring between the board and the transformers to make sure you didn't accidentally swap a plate lead for a UL lead or something. Use your ohmmeter (amp should be off & unplugged) and make sure nothing is shorted to ground where it shouldn't be.
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