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Chassis pull has Low volume on phono inputs

angelaudio

angelaudio

Super Member
I have a hoffman chassis pull that’s working fine except for one issue. When I plug my turntable into the phono input I have to crank the volume up all the way to hear any sound and even then it’s very low and no bass. Any idea what could be going on?

It’s a chassis pull from a Hoffman console which has an old Gerrard in it that isn’t turning. The chassis is stereo and has R + L rca jacks for phono and I screw the ground cable on to an existing screw which I cleaned to ensure good contact. RCA phono jacks were also cleaned.

The amp does not do this when I play an auxilary source. I have attached the schematic if that helps at all.

TIA
41EC8A76-7207-4340-A253-8BD5C5681EDC.jpeg
 
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Well there doesn't appear to be a phono stage, so that would explain what you're hearing, or not:) Is it possible that there was a preamp section (with tuner) that was separate from the amp in the console?

jeff
 
I have a stromberg carlson that says phono but no riaa section.I use a little bear preamp on phono section for it to work
 
vinylkid58 said:
Well there doesn't appear to be a phono stage, so that would explain what you're hearing, or not:) Is it possible that there was a preamp section (with tuner) that was separate from the amp in the console?

jeff
Click to expand...
Thanks for the clarification. The console does have a tuner section which isn’t functional but when I got the console the rca jacks from the changer were plugged straight into rear of the chassis in question which is why I was assuming that I could plug my TT right in. :dunno:

I was doing some guesswork troubleshooting and plugged in the remote balance jumper plug into the back of the chassis as well but nothing happened. Any idea what the ‘remote balance’ jumper plug does?
 
hugo454 said:
I have a stromberg carlson that says phono but no riaa section.I use a little bear preamp on phono section for it to work
Click to expand...

That’s the only way I’ve been able to get it to play my vinyl. So I’m guessing your Stromberg is 50’s era correct? My hoffman is late 50’s I believe.
 
buickguy62 said:
The Hoffman may have had a ceramic cartridge with a higher output that you get with magnetic carts.
Click to expand...
Yes, that is exactly what the problem is. If the original poster takes the phono cartridge out of the Garrard and installs it on his phonograph, he should have normal phono performance.
 
I have the mono version of this, and yeah, no mag phono stage.

Is the tuner in yours FM stereo or mono? Mine is mono but its an older model. 2 piece console too, one amp per cabinet.
 
ceramic inputs don't have a real EQ network. Ceramic carts more or less self-equalize, the only EQ they typically get is a bit of a resistor loading that only affects the very high output impedance of the ceramic cart. Feed it with a phono preamp or anything else that has reasonably low output impedance and that connection acts like any other input.
 
gadget73 said:
I have the mono version of this, and yeah, no mag phono stage.

Is the tuner in yours FM stereo or mono? Mine is mono but its an older model. 2 piece console too, one amp per cabinet.
Click to expand...
I have the mono tuner. Only one rca jack on it. I think I’ve seen your model. I almost snagged it when it came up for sale locally but I wasn’t sure if the amp was stereo. Now I regret not buying it, I thought the extra cabinet was just a speaker :crazy:
 
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