Re: Problem with my stereo receiver

BenHagerty · Post by **BenHagerty** » Sun Oct 05, 2008 2:32 pm

Ok, I am not sure what section for this but,

I have a I think 1976 Fischer Receiver and it has been a little finicky. When I use my turn table the volume is noticeably quieter, like if it is turned up all the way it is loud, but not what I would expect for it being on 10. So then I switched to the radio (while on 10) and it was fucking loud as hell. What is the deal? Why is it quieter with the turn table?

øøøøøøø · Post by **øøøøøøø** » Sun Oct 05, 2008 2:49 pm

you are probably not plugged into the "phono" input, or something is wrong with the line amp on the phono input.

The phono input is different than "aux." It has much more gain. So if you plug a turntable into "aux" or anything except a dedicated phono input, it will sound very quiet.

Maggieo · Post by **Maggieo** » Sun Oct 05, 2008 2:58 pm

øøøøøøø wrote: you are probably not plugged into the "phono" input, or something is wrong with the line amp on the phono input.

The phono input is different than "aux." It has much more gain. So if you plug a turntable into "aux" or anything except a dedicated phono input, it will sound very quiet.

IIRC, phono jacks have an additional preamp to deal with the RIAA curve on LPs. They have to reduce the amount of bass when they cut the discs, because the grooves can only be so wide, so you need a specially tweaked preamp to restore the bass frequencies to their proper volume on playback.

BenHagerty · Post by **BenHagerty** » Sun Oct 05, 2008 3:00 pm

Yeah, it was in phono, then I plugged it into aux and it was extremely quiet.

I fiddled with the cables and it sounded a little better. I don't know, I am getting new foam for the speakers so I am sure that will help, it hasn't been changed it over 20 years.

øøøøøøø · Post by **øøøøøøø** » Sun Oct 05, 2008 3:18 pm

Maggieo wrote:
øøøøøøø wrote: you are probably not plugged into the "phono" input, or something is wrong with the line amp on the phono input.

The phono input is different than "aux." It has much more gain. So if you plug a turntable into "aux" or anything except a dedicated phono input, it will sound very quiet.
IIRC, phono jacks have an additional preamp to deal with the RIAA curve on LPs. They have to reduce the amount of bass when they cut the discs, because the grooves can only be so wide, so you need a specially tweaked preamp to restore the bass frequencies to their proper volume on playback.

That is absolutely correct. The phono section has an extra line amp stage and an RIAA corrective filter.

Ben:

If the foam in the speakers has deteriorated or is missing, do not play the speakers until it is fixed. That foam keeps the voice coil centered in the gap. That loud burst when you turned on the radio with it cranked up to "10" could've been the death knell for those speakers... if they made it out alive consider yourself very, very lucky.

If the line amp in the phono circuit is not working properly, then that would result in a weak output. So, of course, could a bum cable or other short. So make sure everything is sorted out.

Is this amp tube or solid state?