Altec 1589b Hiss
Altec 1589b Hiss
Hello TapeOp. I have acquired an Altec 1589b. I recapped the entire unit, have 3 1588b preamps and have a hiss in my output. I've traced back with an audio probe thru the circuit and hear an audible hiss in the AL2712 transistor and the corresponding resistors. I've checked the voltage at the AL2712 and it is around 30v at the collector and the emitter and base are around 22v. I swapped out resistors R113 and R108 as they were out of spec. The hiss is definitely louder as I increase each channels gain. I see a small ripple of distortion hitting the output tranny back to AL2712. Is this a tranny issue? Any advice would be appreciated. Also any advice on grounding as I do notice when i mixer the xlr/ mic connection I do get some static.Thanks for your help.
Anyone who has never made a mistake has never tried anything new.
Albert Einstein
Albert Einstein
So I traced the circuit again and it appears there was a bad connection on a resistor. I replaced it wit the same value and it has minimized the hiss. I'll ultimately try and verify I have no ground loop issues and if that does;t quiet her down I'll try and upgrade the transistors. Thanks again.
Anyone who has never made a mistake has never tried anything new.
Albert Einstein
Albert Einstein
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