Pre amping a ceramic cartridge

[stevekendal]

Can anyone recommend a cheap and cheerful circuit please for boosting a low output ceramic cartidge enough to fully drive a single stage valve amp in an old Dansette?

[bikerhifinut]

How much gain do you want Steve?
And would you be ok using an op amp with a 9V battery, or a simple PSU off the mains?
I'd just knock up a basic TL071 or similar op amp, even the older LM351 would do.
I've got a few bits and bobs here that I won't use if you want a LM351 for free.
Just make sure you jig your circuit to have about 1Meg input resistance, this kind of dictates a non inverting design.
I've attached a simple circuit that will do the job, remember if you don't use a battery you will need a couple of extra caps toad a bit of stability and to decouple the power supply in on the bias network.
Drop me a message if an op amp and a few resistors and caps will be any help.
Its out of my "ladybird book of handy op amp circuits" . The babani book of preamplifier circuits by RA Penfold.
The Author does recommend that you include decoupling and filtering when using an external power supply, I generally just knock up a simple 317 regulated supply for stuff like this if not using a couple of PP3 which would last a long time.
Andy

[Nickthedentist]

Good old R.A. Penfold, Andy?

[bikerhifinut]

There was a good article in a past Bulletin on this Steve. I probably have lost that edition.
Forgot to add, you can adjust the gain with the feedback resistors I'd think about a preset pot in place of R3 which will allow you to set the required gain quite precisely.

A.

[bikerhifinut]

Originally Posted by Nickthedentist

Good old R.A. Penfold, Andy?

Yeah that's the man, Its a handy little volume especially for those of us who aren't quite so knowledgeable in the Electronics field.
Much of what criticism can be made on the basic circuits is actually covered in the initial chapter where he does discuss decoupling supply rails and biasing and stability etc. Then you have to make your own wisdom from the basic circuits.

You could also use one of those handy velleman PCB kits which aren't expensive, however they are an inverting design which means a 1 meg input resistor here and for 5x gain you'd be using a 4.7M feedback resistor from the output pin which aint conducive to low noise and good stability I think.
I also notice he's using a 10 uF output coupler, ok for into a solid state input but for a valve record player you'd be fine with a 0.1uF

A.

[bikerhifinut]

Just bumping this up as I don't know if Steve has got himself a solution sorted out.
Andy.

[af024]

There's also this ...
https://www.vintage-radio.net/forum/...ad.php?t=65007
and I seem to recall another (more recent one) for single UL series amps (and possibly other configurations), if only I could remember the link ...

[af024]

Ah, perhaps they were these ones I was thinking about ...
https://www.vintage-radio.net/forum/...d.php?t=150927
and;
https://www.vintage-radio.net/forum/...=128765&page=5

All good fun.