Magnavox Phono Scratch Filter

Electrically amplified phonographs or radio/phonographs and related components (approx. 1928-1990).



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TomTom
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Magnavox Phono Scratch Filter

by TomTom » Sat Feb 04, 2012 7:32 am

The phono inputs on my Astro Sonic chassis have a .015 uf capacitor on each of the phono input channels to ground which I perceive to be used as a scratch filter and I thought that I would remove them to open up the treble a bit from the turntable. Does anyone know if these capacitors would be used instead for cartridge/chassis matching and should stay in the circuits? The cartridge is an Astatic 461 and the chassis number is R204-03-00. Also, does anyone have a sound preference between an Astatic vs an Electro Voice equivelant? In my case, the cartridges are Astatic 461,and the Electro Voice is #150. Thank you much.

Tom

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MattTech
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Re: Magnavox Phono Scratch Filter

by MattTech » Sat Feb 04, 2012 9:51 pm

According to my Magnavox service data, there are two .05uf's, not .015uf's, across the cartridge input jacks.
They can be removed if you feel the treble is too muted.
There is also a 22K resistor bridging the input, which can be clipped out to increase stereo separation.
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Record-changer
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Re: Magnavox Phono Scratch Filter

by Record-changer » Tue Feb 07, 2012 5:35 am

For the original cartridge, they provided the RIAA compensation when combined with the characteristic of the cartridge.

Remove it if you have a different cartridge.
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Topic author
TomTom
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Re: Magnavox Phono Scratch Filter

by TomTom » Sat Feb 11, 2012 8:01 pm

Thank you Mattech and Record-changer for your replys. I did remove the capacitors and the result was a very thin sound with the highs overloading the amp input, causing a little distortion. The capacitors are back in now and the sound has returned back to "normal" so they were needed to load the cartridge properly. Well, I was just curious...

Tom

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