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 Crystal cartridges
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 Return to top of page · Post #: 1 · Written at 6:44:50 PM on 28 August 2012.
Sue's avatar
 Sue
 Location: Daylesford, VIC
 Member since 13 January 2011
 Member #: 809
 Postcount: 326

Stereo crystal cartridges can be wired for mono in series or parallel. If I've got a 1 megohm input impedance, which way would be best? How does changing the input impedance affect the frequency response of a crystal cartridge?


 
 Return to top of page · Post #: 2 · Written at 9:24:56 PM on 28 August 2012.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

It would depend on the way the radio is intended to be fed. The newer sets used crystal more so than magnetic. Albeit HMV used plenty of magnetic's.

Normally if there is a huge mismatch of impedence you will get distortion. If the high impedance is going into a grid you may well be OK.

I would expect parallel to give more voltage. but make sure the Phasing is correct.


Marc


 
 Return to top of page · Post #: 3 · Written at 12:36:23 PM on 4 September 2012.
Sue's avatar
 Sue
 Location: Daylesford, VIC
 Member since 13 January 2011
 Member #: 809
 Postcount: 326

Thanks. I've tried parallel now, and there's more volume and slightly better bass.

I found some 1940's R&H's on Sunday with some useful info. A crystal cartridge acts like a capacitor; it loses its bass response when fed into a lower than optimum impedance. So parallel would be the way to go under most circumstances.


 
 Return to top of page · Post #: 4 · Written at 10:27:50 PM on 4 September 2012.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5239

The HMV units like the R53B & similar with magnetic cartridge, are fitted with an impedance matching circuit, which is I would suggest, is also intended to impinge on the audio.

The crystal is more of a Piezo electric device, as used in BBQ lighters etc. and is actually high impedance, as it has, for our purpose, infinite resistance.

This is one reason I considered parallel likely more satisfactory and then there is the issue of stereo records.

Marc


 
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