Help - Grundig 8055/W/3D

[PJC58-Hythe]

I'm currently repairing a Grundig 8055/W/3D with an outboard circuit which is a clearly a pre-amp with some equalisation. The input states "Collaro Transcription Cartridge" and the output is connected to the normal PU input. My question is what is the Collaro cartridge mentioned (it's missing from the arm) I've never run across one of these.

Hoping someone can help

[Edward Huggins]

This is liable to be for the Collaro Studio "P" crystal cartridge (c.50mV) or the (even better) Collaro/Ronette TX88 cartridge. Both are rare, have wide frequency ranges and a relatively low output - hence the pre-amp add-on circuit.

[PJC58-Hythe]

Thanks for the information Edward, that now makes sense. Looks like I'm going to have to install a ceramic pickup and skip the pre-amp if they are so rare.

[PJC58-Hythe]

To keep the circuit original I used a Sontra CS25 stereo ceramic cartridge which has the following specification:

Output: 45 mV 1cm/s at 1000 Hz
Frequency Response: 20Hz to 18 kHz
Compliance: 6 x 10(-6) cm/dyne
Tracking Force: 3 to 5 grams

It sounds fantastic!

[Edward Huggins]

Originally Posted by PJC58-Hythe

Thanks for the information Edward, that now makes sense. Looks like I'm going to have to install a ceramic pickup and skip the pre-amp if they are so rare.

No, you will still need to use that dedicated pre-amp section. Most "new" ceramic stereo cartridges have a far lower output than you might expect!

[PJC58-Hythe]

It's not a 'modern' cartridge it's an original Sontra coupled to the pre-amp.

The output is exactly right when switching between Radio / PU - and as I said it sounds fantastic!