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Silvertone Console 69A Low Phono Output

T

Tdlunsfo

New Member
Restoring this console for a buddy and I am getting pretty low volume out of the phonograph. At first I thought it was the cartridge so I jumper-ed a modern turntable in circuit and it gave me even less volume. Looking at the schematic and all input sources go through the same amount of preamp stages. Is it possible this turntable has always been weak and this is a crappy design? I compared it to my Lafayette LA240 and the phono in that circuit has a whole other 12AX7 to boost the signal. Anyone have any experience with this unit or thoughts on the below schematic?
Pre1.PNG Pre2.PNG
 
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The phono input on this amp looks to be for a ceramic or crystal cartridge. If you connect your cd player to these phono inputs, you are probably going to get good sound like it was an AUX input.

Your modern turntable probably has a magnetic cartridge and needs to be boosted by a separate preamplifier.
 
Good point, Im pretty sure my daily driver TT is a ceramic so I'll hook it up and retest. I still think the volume will be too low though but maybe it will surprise me.
 
Tdlunsfo said:
Good point, Im pretty sure my daily driver TT is a ceramic so I'll hook it up and retest. I still think the volume will be too low though but maybe it will surprise me.
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You must be using a very old TT then. If it was made after the 1960s it's almost certainly a magnetic cartridge model.

Try the input with a CD or DVD player, as Century suggested. If the volume is still low, it's an issue with the circuit.
 
Sorry I wasn't clear above. I have yet another TT that I use as my daily driver -Phillips GA212 that I was going to try but it appears to also have a magnetic cart like my spare modern Sony. I have a signal generator, at what output should I connect it to simulate a good ceramic cart? I get good volume out of the radio and the tape inputs so this is why I am leaning toward it either being a bad cart or a poor designed circuit. Next issue is the cart is a Sonotone 8Ta and it appears these are pricey to replace. Is there a good modern day equivalent that won't break the bank just in case the cart turns out not an issue? I don't think my buddy would care if it isn't top of line as long as it works correctly, plus this isn't the best sounding preamp in the world.
 
Yeah I actually considered making my own with some opamps or a LM386. I've done similar before in a tube amp by rectifying one of the heater legs off the 12ax7.
 
My usual source for ceramic stuff is thevoiceofmusic. Mag cart with an RIAA stage is usually a better performer though.
 
There are a few that aren't bad, Sonotone had a couple models that are supposed to be pretty nice. The one in the Zenith 2g MicroTouch console I've been sitting on for a friend for way too long sounds pretty good too.
 
I ordered a new ceramic from VOM - Varco TN4A . The sonotone that's in it is very weak. With the volume, treble, bass all the way up I am getting less than a watt out of the speaker outputs. With my phone connected to the tape input, I am getting 7-10W.
 
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