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76.25.11.220
Speakers: Magnepan 3.6R
Amp: Pass Labs 250.5
Preamp: Pass Labs X1
Problem: Tweeter in Left speaker was exhibiting a kind of static for one or two songs featuring piano. Problem is intermittent. Tried a variety of diagnostic things and decided to replace the tweeter as that seemed to be the issue. Problem continues.
Switch L-R output from preamp to amp. Problem stays in L tweeter. Put connections from pre-amp to amp back to normal L-R configuration. Then, switch L-R speaker cables in back of amp--now, problem is in R tweeter (not L tweeter).
This would suggest to me that the problem may be in the amp itself. Have I missed any other possible interpretations? or diagnostic options? Thanks for your help.
Follow Ups:
First, thanks to everyone for the suggestions. After switching the speaker wires completely, and after warming up the amp for about half a day, I was able to replicate the problem in the L tweeter. So, note an issue with any of the upstream components, and not an issue with the speakers, crossovers, or connectors. That leaves the amp, with the problem only showing up on the L side, and only after the amp is quite warm.
Seems to me that it's back to the factory for the amp.
Thanks again for the input.
I mentioned the problem appears to be intermittent, but I have now noticed that it's more likely to appear if the amp has been on for a while and is warmed up. This would again suggest to me that it's an amp issue and not a speaker wire issue. thoughts?
If you just swapped the speaker cable connections at the amplifier then there are two possibilities: One is that the problem is with the amp, and the other is that one of the cables has a problem. To r/o the cable as the culprit, try completely swapping the cables or using a different cable altogether.
I married the perfect woman. The downside is everything that goes wrong is my fault.
Ah, good point. I'll try that.
Try swapping the speaker cables to eliminate a termination problem, assuming your cables have terminations, loose or oxidized. Bare wire will oxidize too.
Edits: 02/12/17
Doing that today. thanks.
But Ive had a few cutomers with issues around the 3.6 connection points. Clean and reseat the fuses and the conne tion points and that tweeter attenuator on the top right. If that doesnt solve things look at the crossovers.
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
I've done that. Also don't think it is the crossovers as the problem did move from L to R when I switched the speaker cables from L to R, and the crossovers stayed in the same position.
ah ok
ET
"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936
;-)
Check the internal amp to speaker connectors inside the amp
Also are there ANY switches in the signal path inside the amp
(for example my Bryston 4B-SSTē has two switches, one for gain, one for RCA vs XLR. BOTH are in thesignal path and could affect the signal in your way.
If you have any such switches, flip them a bunch.. Clean the contacts off.
Thanks. I can't see any such switches, and the speaker contacts inside the amp are tight and perfectly clean. I did clean all connections for all components and speaker wires earlier, but the problem persisted.
Edits: 02/11/17
How old is the amp? Almost sounds like a main PSU filter cap issue.
Thanks. Very well could be. I purchased it used, so don't know the original manufacture date. I just want to be sure it is the amplifier because it is a bit pricy to send (and hard on my back!). I know Pass will do a good job of repairing it. I can't think of anything else it could be at this point.
There may be a fractured solder joint on one of the output devices. If so, touch them all up.
Dark energy? Ridiculous!
We live in an electric universe.
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