Time for a new cartridge?

[Crackle]

I reckon so.
   
This was in a Dansette record player my wife bought at a bootsale last year.
   
I have fitted a GP91-1 cartridge and borrowed a stylus from my KB KP031 player for now until the new stylus arrives.

The record deck mechanicals have now been un-gummed and serviced, it is working quite nicely now. The amp has just an ECL82 and metal rectifier.
I have bypassed the rectifier with a IN4007 and 100 ohm resistor and changed most of the components now in an attempt to get the volume up.
HT on the ECL82 pentode is 198v and on the triode about 85v.
Were these known for being a bit weedy on the output. The quality is fine but it is not as powerful as any of my KB or ITT record players.
The GP91 was the loudest and best sounding cartridge I had in my spares.



Mike

[Refugee]

That old cartridge would have been a short lived high output part. An extra gain stage will need to be added to get the volume up to something useful.

[Murphyv310]

Hi.
The ECL82 was actually OK with a decent cartridge, there were still many of those record players around in the early 70's and they were OK. The UL84 only ones were grim but that extra triode made a world of a difference.
I'd fit this one http://www.musonic.co.uk/index.php?main_...oduct_info&cPath=4_431&products_id=18696
at 500mv the amp should be driven into distortion.

[Crackle]

I have just checked again and the cartridge I have fitted is a GP91-1sc, I believe this is a crystal cartridge, and the SC stands for stereo compatible.
Does it have a higher output than the GP91-1 ceramic one. Would it be as high output as the original red cartridge in the photo, which was a FulFi TC8H.

Thanks
Mike

[FIXITNOW]

specs for GP91-1 and -3

[Crackle]

Thanks
So what I need is a GP91-3sc or a Ronette DC284 Mono Cartridge Copy.

cheers
Mike

[Murphyv310]

You'd either need the 91-3 or the TC8-H to get full output. The one I linked earlier would be a suitable replacement, as you say Mike the Ronette.

[Terry]

Mike, all GP91 series cartridges are ceramic. The later SC version stopped these mono cartridges damaging the grooves of stereo records. See here for an explanation.

Older crystal cartridges usually have a much higher output than the later ceramic types and the BSR TC8H, in particular, had a very high output - thus the H suffix - capable of driving a UL84 directly, thus creating a series of cheaper one-valve record players.

I wouldn't expect to see a TC8H driving an ECL82, though. The TC8M (medium output) would be the usual choice. I don't have comparative information to hand but I would expect the TC8M to have a higher output than the GP91-1, though.

I'm wondering if the TC8H was fitted to overcome a low gain fault in the amplifier in the past? It might be worth more investigation.

[Murphyv310]

Hi.
There is no reason why a high output cartridge shouldn't be fitted, the volume control will be most likely at the Triode's Grid so all it needs to be is set lower.
Many workshops only stocked the high output versions with a small stock of turn over or turn under types.

[Crackle]

I'm wondering if the TC8H was fitted to overcome a low gain fault in the amplifier in the past? It might be worth more investigation.

You could be right Terry. The original volume pot in the record player was marked as 1M B but it measured 275k ohms.
In my limited experience I have never known a pot to go significantly low, they always seem to go high.
This would probably have an effect on the working of the cartridge as it is wired directly across the 2 ends of the track of the pot.
Apart from loss of volume I think it may also result in a significant loss in bass response from the cartridge, must have sounded horrible.
Anyway I have now fitted a new 1M pot.
I have assembled it all back together and the volume issue is not so bad now the twin speakers are fitted in the cabinet. It is louder and now more comfortable listening at close quarters with the volume down by about a 1/4 from full, but it still does not go into distortion.
There is a problem with the GP91-1sc cartridge, it is distorting in phases, on some records, as the record rotates. It gets worse if you increase the stylus pressure, but the pressure is more or less on the minimum to keep the stylus following the grooves.
I have ordered a new stylus, but I may end up having to order a new cartridge altogether. (I wondered why the GP91-1 was in my spares box, probably came out of a KB at some time)

Mike