Experimenting high pass filter on old turntable

[Hiten]

Hi everyone,
I have old three speed idler wheel drive Philips TT with ceramic cartridge. While playing I noticed by touching the tonearm it had good resonance from vibration of motor. I have replaced hardened rubber bushes used to hold the motor and changed TT's feet. Vibration was significantly dampened.

Now just to experiment can a passive and simple (one cap + one resistor like following fig.) high pass filter be connected to output from ceramic cartridge ? so that rumble noise of 1030 Hz range can be cut off. If possible, how to calculate values of cap and resistor ?

Thanks

 

[Hiten]

Alternatively, you can simply connect a small pot in parallel with the input of the preamp. Bass response from a ceramic cartridge drops drastically with reducing impedance of the loading stage - so by playing with the pot you can reach the right value experimentally.

GREAT, that should be easy. In fact at rear of TT it has 5 Pin DIN socket.

I have just to find out ground (I think center pin) and one channel line out. Correct ? Will 220K pot do the job ?
Thanks Cranky

 

[Hiten]

OK here is my life's first mod

With 1 Meg control change is very sudden I mean with 1 to 2 mm turn the 'volume' changes. As for low pass cut I think slight boominess is reduced in SQ, not sure. Will try with half the value of pot (470K ?). If I decide to put cap in series + 470K pot which value cap should I go for ?
Thanks

 

[Hiten]

Thanks a lot Cranky,
Got 500K Pot and cap you mentioned. Connected in parallel and series. Dont know about rumble noise but sound did felt liked opened up.

Here is different 'spin' on this experiment. Connected line out of TT to PC. (No cap or pot soldered). Recorded little sample with no song playing with motor off and other with motor running . Here are pics. With motor running pic. there is little peak circled yellow. It says 86.13 Hz. R= -46.92 dB. Your views will be very much appreciated.

Thanks a lot again
Hiten

 

[Hiten]

Are you keen to rewire the tonearm? This can help a bit with the LF, and try a proper sleeve. Be warned though, it may not fix the problem completely.

Yes will do that.

Note that the turntable's stock pickup is not designed to feed the line input of a PC (impedance is ~20-50K ohms) but a high-impedance input - ideally a tubed gain or buffer stage with a large grid resistor (above 1 megohm).

That's what my plan is. Will hookup TT with old valve radio. Heard this combination at a technician's place. Sound was sweet.

Keep your expectations real. You can't expect a donkey to run the Derby

sure, this is just fun+experiment+get to knowing things effort.
Kind of like knowing how donkey runs and if using a whip will make him run a little faster. :lol:
Thanks