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Vintage Gramophones and Phonographs

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 HMV 35-62 Nippergram equaliser circuit.
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 Return to top of page · Post #: 1 · Written at 11:31:34 AM on 31 October 2023.
Sirwin's avatar
 Location: Beechmont, QLD
 Member since 10 April 2009
 Member #: 465
 Postcount: 109

Hi all.

The above Nippergram uses a Collaro RC54 changer, which I have working reasonably well.

I of course changed the cartridge, as the original was useless. I used a ceramic cartridge part number PC-01 from Wagner, which seems to work OK, but the sound isn't great. My question is do you have to alter or change the equaliser circuit on the turntable to suit the new cartridge?

I haven't re-installed the chassis and changer in the cabinet yet; just trying it on the bench with my bench test speaker. It my sound better with everything in the cabinet.

Any advice?

Cheers, Stuart


 
 Return to top of page · Post #: 2 · Written at 10:21:16 PM on 31 October 2023.
DangerousDave's Gravatar
 Location: Toongabbie, VIC
 Member since 1 September 2020
 Member #: 2438
 Postcount: 129

You may have to experiment Stuart. I remember these things not liking low Z input circuits with loading issues. Have you experimented with a high Z buffer stage just to see if there is any difference or improvement. Even a simple Fet circuit just for testing might prove a point. Your input impedance might be restricted by the volume pot, depending on the circuit. If it's sounding a bit shrill you could try and shunt it with a capacitor to tone it down. I think quality of these modern replacements leave a bit to be desired which doesn’t help either.
Dave


 
 Return to top of page · Post #: 3 · Written at 3:26:00 PM on 3 November 2023.
Sirwin's avatar
 Location: Beechmont, QLD
 Member since 10 April 2009
 Member #: 465
 Postcount: 109

Hi Dave. Thank you for that. I did experiment with capacitive shunts, but that just reduced the volume, which no noticeable effect on the tone. However, I tried it with a different speaker, and found that on it the bass response seems to be good now. Funny, because it sounded alright on radio. The treble response is not great though. It does already have a shunt capacitor of 1nF, so I might try reducing that.

Another problem has arisen though, if I may. On some records, the stylus skips ahead quite frequently. It happens on some songs more than others, and on newer records more than old. It seems the anti-skating needs to be adjusted, but there doesn't seem to be such on this changer. Can anyone suggest a fix please?

Regards, Stuart


 
 Return to top of page · Post #: 4 · Written at 12:03:07 AM on 7 November 2023.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5221

The circuit of the PU part is under 35-62 and the chassis is a separate listing as chassis 35 All on Kevin Chants site.
Turntable also used in R53 but into a 6N8 duo diode pentode. OP is type #807 in that one and it puts out lots of watts.

R54 and its settings are in AORSM's.

If not discovered that little module will have dud caps.

If I have signal issues, or poling speakers, with audio amps; I tend to use a function generator as the signal source. Often with an Oscilloscope if I suspect distortion

Marc


 
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