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 Post subject: Philco 46-1201 Phono/Radio Question
PostPosted: Oct Mon 11, 2010 4:01 pm 
Member

Joined: Sep Thu 11, 2008 3:43 pm
Posts: 349
Location: Miami, FL
Hello,
I'm restoring a Philco "Bing Crosby" 46-1201 phonograph. I replaced the crystal cartridge with an Astatic 8978B. The problem is the cartridge causes the sound to overdrive. I already toned it down with a resistor installed at the terminals where the tone arm wires go but I'm still not happy with the sound. It distorts, especially when the music has multiple voices or solo piano. Any suggestions?


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 Post subject:
PostPosted: Oct Mon 11, 2010 5:12 pm 
Silent Key

Joined: Sep Thu 23, 2010 5:37 am
Posts: 12437
Location: Powell River BC Canada
If the new pickup is the problem, try using 2 resistors:

In series with the signal wire (center pin) 1 megohm

Across the radio side of that resistor 47 kohm to ground.

If this attenuates sufficiently, but seems to lack highs,
connect 470 Pfd across the 1 meg resistor.

_________________
de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject:
PostPosted: Oct Mon 11, 2010 7:54 pm 
Member

Joined: Sep Thu 11, 2008 3:43 pm
Posts: 349
Location: Miami, FL
Thanks. I'm confused though. I'm pretty new to this. I've posted a photo of the terminals. Can you tell me where each of the resistors you're talking about go? In the photo, from left to right, numbers one and two are the tone arm leads and number three is ground. I think four is radio.

Thanks for your help.

Image


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 Post subject:
PostPosted: Oct Mon 11, 2010 7:55 pm 
Member

Joined: Jan Thu 01, 1970 12:00 am
Posts: 16796
Location: Albuquerque, NM 87123
The problem is that now the pre-amp stage does not match the impedance and output of the new cartridge. You will need to re-design the amplifier.


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