Marantz 2230 low freq phono noise

[jtpal25]

I just purchased a 2230 for a good price. The aux and tape channels work perfectly. The phono channel sounds great with the exception of an intermittent low frequency noise that comes usually when there is a low bass part or deep kick drum parts of a record. It's subtle and just barely underneath the music, but it's definitely there and it definitely bothers me. Any ideas? I've been reading a bunch of threads on here already and it seems maybe transistors in the phono stage, but I haven't found anyone with the same exact issue I'm having.

I know my way around guitar tube and solid state amps pretty well. I've built 2 tube guitar amps from scratch, and do repairs for friends, but I've never set fingers inside of any hifi audio equipment aside from cleaning pots. So with some guidance, I'm somewhat confident I could handle anything going on in there.

Thanks in advance to anyone willing to help me out.

 

[OutlawSun]

What kind of sound are we talking?

 

[Steven Tate]

Any chance it's feedback from the turntable not having enough sonic isolation? That has been a big problem for me in the past. When the room and the furniture vibrates to the bass, the turntable can pick that up and send it back through as low frequency rumble.

 

[jtpal25]

The sound is like a low frequency static sound and it’s not constant. It’s only during low frequency parts of the music.

I’m pretty sure it’s not vibration. The aux channel works perfectly so I hooked the TT up to the aux channel with an external phono pre amp and there was no noise at all.

 

[bberkom]

If it's static in the phono section of a 2230, I would guess transistors. The SC458 transistors are known to go bad and should be replaced. Fairchild KSC1845 from mouser are what I have used in the past as replacements.

 

[rBuckner]

^^^ What bberkom just said! I'd recommend recapping it too and replace the "blob" diodes. The one by the pots, H709, needs replaced with two in series and the 1N4148/1N4448 type will work fine. H707 and 8 are single 1N4148 types.