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It hisses. I just had one in the shop and it did not hiss. I plugged in to the headphone and xlr line out and there is no hiss. I am assuming it would be in the output section. Suggestions on what to be looking for?? Could not find any loose grounds and bad solder connections. Resoldered cold joints on all pots and jacks. I have attached a schematic.
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Reasonable to assume it is from the power amp. Hiss is usually associated with gain, so the first suspect is the IC. Replace the 5532, U3.
Scope the circuit. The hiss ought to be visible on pin7 of U3. Is it on pin 1 as well?
One of those JFETs could be noisy.Education is what you're left with after you have forgotten what you have learned. -
I am seeing the noise on both pin 1 and pin 7. I need to place an order for the chips. Would it be wise to order the transistors aswell (Q1-Q8) or just the FETS?Comment
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It is only my opinion. I doubt that hiss is coming from your output transistors, especially since you find the noise on pin1 of the IC.Education is what you're left with after you have forgotten what you have learned.Comment
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So it seems that the ground noise on pin 1 of U3 was caused by choosing a poor ground for my scope probe. The noise is definitely visible on pin 7 and not on pin 1. I replaced U3 and the output FETS and still see noise.Comment
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Yup im a newbie for sure. I replaced Q1 and Q4. Problem solved. Thanks for the help as allways enzoComment
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I can't take much credit, I didn;t steer you towards those drivers. Glad you got it straightened out.Education is what you're left with after you have forgotten what you have learned.Comment
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