Your MC's coils are likely to melt before any discernable effect on your
MC cartridge, which by definition is permanently magnetised one way.
(Very much like a loudspeaker driver)
Generally its a choice of the difficulty of having high quality coupling
capacitors due the capacitance values required versus leaving them out
and having some harmless DC offset current through the cartridge.
What is the DC offset and your cartridges DC resistance ?
sreten.
MC cartridge, which by definition is permanently magnetised one way.
(Very much like a loudspeaker driver)
Generally its a choice of the difficulty of having high quality coupling
capacitors due the capacitance values required versus leaving them out
and having some harmless DC offset current through the cartridge.
What is the DC offset and your cartridges DC resistance ?
sreten.
The Threshold M1 circuit used bipolar transistors operated
in common-base mode, so that they cascoded the output
of the MC cartridge. The Emitters were driven, the Bases
were grounded (AC) with a DC bias, and the output came off
the Collectors. No feedback, very low noise, low distortion.
The current from the Emitter went through the coils, but it
was only a few mA, and did not cause problems. You could
easily argue that it in fact biased up the wire connections,
magically improving them.
in common-base mode, so that they cascoded the output
of the MC cartridge. The Emitters were driven, the Bases
were grounded (AC) with a DC bias, and the output came off
the Collectors. No feedback, very low noise, low distortion.
The current from the Emitter went through the coils, but it
was only a few mA, and did not cause problems. You could
easily argue that it in fact biased up the wire connections,
magically improving them.
I thought you were taking about a much smaller offset,
3.4V is a lot and you should be very wary of attaching
a MC to it.
Does your signal generator have low DC impedance ?
Certainly try connecting a resistor equivalent to your
cartridge, low/medium MC's are 3R to 10R usually,
and see what the offset voltage value is.
From your description it seemed that it is working and
presumably both channels have no output offset and
similar input offset ?.
It does seem a lot.......
sreten.
3.4V is a lot and you should be very wary of attaching
a MC to it.
Does your signal generator have low DC impedance ?
Certainly try connecting a resistor equivalent to your
cartridge, low/medium MC's are 3R to 10R usually,
and see what the offset voltage value is.
From your description it seemed that it is working and
presumably both channels have no output offset and
similar input offset ?.
It does seem a lot.......
sreten.Thank you Nelson and Sreten,
I use a Sound Technology 1500 Analyzer System which I believe is 50 ohm or lower output impeadence. Hooked up to the generator, the offset drops to 0.24v.
It is comforting to know that the S-10 is working as designed since I'm anxious to give it a listen. Now I just need to get a new Level control. Evidently the original one wore out and the previous owner took it to a TV repair shop. The control in there now looks like it belongs in a '50s HiFi Console.
Does anyone know the design value of the control? If I remeber correctly my old NS-10 used a 10K, wire-wound, Spectrol control.
Thanks again,
Doug
I use a Sound Technology 1500 Analyzer System which I believe is 50 ohm or lower output impeadence. Hooked up to the generator, the offset drops to 0.24v.
It is comforting to know that the S-10 is working as designed since I'm anxious to give it a listen. Now I just need to get a new Level control. Evidently the original one wore out and the previous owner took it to a TV repair shop. The control in there now looks like it belongs in a '50s HiFi Console.
Does anyone know the design value of the control? If I remeber correctly my old NS-10 used a 10K, wire-wound, Spectrol control.
Thanks again,
Doug
Er. . . Ah . . Potentiometer 
Threshold SL10 problem
Hello Nelson, i have a question for you,
i use a Threshold SL10 preamp and a Threshold TA300 poweramp very nice component, now i have a problem in SL10 preamp.
I have found (with multimeter) in left output channel a DC 0,12Volt and this is a problem for my poweramp and woofer (a strange and unusual movement at burn in ), the pre sound well (or i think well!) but i'am worry for the poweramp and woofer safe.
From what to be caused this? can you help me?
thank you
Pierluigi (Italy)
Hello Nelson, i have a question for you,
i use a Threshold SL10 preamp and a Threshold TA300 poweramp very nice component, now i have a problem in SL10 preamp.
I have found (with multimeter) in left output channel a DC 0,12Volt and this is a problem for my poweramp and woofer (a strange and unusual movement at burn in ), the pre sound well (or i think well!) but i'am worry for the poweramp and woofer safe.
From what to be caused this? can you help me?
thank you
Pierluigi (Italy)
Treshold SL-10
Dear DIY buddies,
I now have (long search is over) a nice SL-10. The gain is enormous in this thing and sounds very god. Phono MC has a bit of hum, one channel only. I would appreciate very much if anyone has a pic or scans of the circuit diagrams of this beauty. Also measurement points would be greatly appreciated thank you.
Mario
mgrouwenhorst@hotmail.com
Dear DIY buddies,
I now have (long search is over) a nice SL-10. The gain is enormous in this thing and sounds very god. Phono MC has a bit of hum, one channel only. I would appreciate very much if anyone has a pic or scans of the circuit diagrams of this beauty. Also measurement points would be greatly appreciated thank you.
Mario
mgrouwenhorst@hotmail.com
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