1950's HMV crystal cartridges

[Phonosandradios]

I have a pair of HMV cartridges for a turntable used in an early 1950's radiogram. There is one for micro groove records and a separate one for 78's. Both are dead and I wondered if anyone had any idea what kind of level of output these would have originally given out - low, medium or high? I have taken both out of their head shells to look for any markings and there are none what so ever.

I am looking to find a modern replacement but have no idea what to look for unless I can get some idea as to what the originals carts gave out. Does anyone know if these would of been considered reliable cartridges and I am just unlucky if having a pair with no output or are most of this type dead by now? I am wondering if it is trying to find working original examples as I plan on only playing 78's and mono LPs on the radiogram.

I have attached some pictures of the cartridges I have. Any help would be gratefully received.

[wd40addict]

They appear to be EMI CP10186 according to 'Points on Pickups'. Apparently when they started failing a mod kit was available using a ceramic Sonotone 2T. Now the 2T is rated at 180mV so roughly twice a modern Chinese job. However this doesn't mean that the Sonotone was the same sensitivity as the EMI. It's quite likely the EMI was crystal hence why it's failed. Best way forward is probably to have a play with a Chinese red/black, they're cheap enough.

[Edward Huggins]

It's likely that those original Crystal EMI cartridges would have given a slightly higher output that a Sonotone 2T. If the Radiogram has a standard triode and pentode (2 stage) amplifier, then a cartridge giving around 250mV output would be adequate e.g. A BSR X5M. However, if as looks likely, only Mono LPs are only ever to be played, then use a BSR (Clone) M TC8.

[Phonosandradios]

Thanks for that input as that gives me a place to start and some suggestions to try.

[Audio1950]

Originally Posted by Edward Huggins

However, if as looks likely, only Mono LPs are only ever to be played, then use a BSR (Clone) M TC8.

With respect, the use of a TC8 would mean having to cut a curve out of the front of the headshell to accommodate the turnover knob. An X5M would be a much better alternative.

Barry

[Phonosandradios]

An X5M has been sourced and is on its way. The cart doesn't come with any mount so once it arrives I will have a look through my spare parts to see if I have something appropriate. If I don't then I'll probably put an ad in the wanted section to see if I can source something.

[ben]

Those carts were used in the RCA 45EY2 players, I have one. I think there was someone in the USA rebuilding them, will try and find the link. Meanwhile, can anyone recall the exact model number or reference of these crystal carts?

[peter_sol]

The cartridges seem to have been made by EMI and are type EM1.
The deck was made by Plessey. A slightly later model had a one piece arm with a rocking cartridge made by Acos.

[Phonosandradios]

Originally Posted by ben

Those carts were used in the RCA 45EY2 players, I have one. I think there was someone in the USA rebuilding them, will try and find the link. Meanwhile, can anyone recall the exact model number or reference of these crystal carts?

Ah, I had forgotten about west tech services if that is who you mean. I might get in contact with them to see if they would rebuild these and if so I might "modernise" the LP one myself but get them to rebuild the 78 one.

[Phonosandradios]

Out of curiosity - I have just noticed that the dead LP cartridge that I took out of its head shell does have the remnants of a yellow dot on the rear part where the connectors go. Does anyone know whether this have any significance?