Ceramic Cartridge Phono Pre-Amp

[williamsunique]

The last ceramic cartridge I had in my system was back in the sixties.  I upgraded this to a moving magnet and this type has been my preferred choice ever since.
I recently obtained two ceramic cartridges.  A Sonotone 9ta and a Decca Deram.  Ceramic cartridges require a special input.  A moving magnet (mm) cartridge input is unsuitable.  A ceramic cartridge requires no RIAA equalisation, in theory it requires no equalisation at all.  It requires a high input impedance, the typical 47k of a mm is far too low.  The 300 plus millivolts of a ceramic cartridge's output is also far higher than the few millivolts a mm cartridge puts out.
I therefore required a ceramic phono pre-amp.  After some thought and research I came up with this very simple circuit based around the INA217 integrated circuit.  The exact requirements a ceramic cartridge need are tailored for in this phono pre-amp.
I was surprised at how good these ceramic cartridges sounded, having read mainly derogatory things about them.  Both of mine were a pleasure to listen to.  The thing that struck me most about them was that they did not cause me any listening fatigue.  The highs, middle and lows were good.  OK fair enough they do not reach the extremes of some of the better designed mm cartridges, but I feel also that they should not be over looked.  I have for far too long.

For stereo you require two of these circuits.  This circuit has x1 gain.  No equalisation correction.  It also has the correct input impedance.  It is designed to plug into the line input of a solid state amplifier.  It is not required for valve amplifiers.





Paul.

[floppybootstomp]

I've always just plugged a ceramic cartridge's output straight into line in. 300mv, no RIAA, there doesn't seem a need for a preamp.

Last ceramic cartridges I used must have been early '74 but I was still fitting them to schools' equipment in the late eighties.

[williamsunique]

I've always just plugged a ceramic cartridge's output straight into line in. 300mv, no RIAA, there doesn't seem a need for a preamp.

Last ceramic cartridges I used must have been early '74 but I was still fitting them to schools' equipment in the late eighties.

You along with many others have done this very thing.  This is some of the reason why ceramic cartidges have been maligned as having little bass and sounding shrill with too much treble.  This is what you get by plugging straight into a line input of solid state equipment.  With valve equipment it is a different story however.
To be clear however the pre-amp of this topic has zero gain.  It has no equalisation.  It does however correct the required high impedance that a ceramic cartridge requires.  Without this high impedance you will have little bass and a thin sound.

Paul

[fetteler]

Sorry, (don't  want to be a pedant!)  a gain of 0 would give no output.

Cheers,
Steve.

Earlier comment edited - it is getting late.... I'm not sure about this circuit...

[floppybootstomp]

Paul, the last time I used  ceramic cartridges it was straight into a valve amplifier and they sounded pretty good to me.

Your impedance matching circuit I find interesting, well done.

The last system I used with a ceramic cartridge at home was an off the shelf unit made by Ultra (Ferguson) and actually sounded pretty good, lottsa bass. perhaps they employed a similar circuit?

The other way I used ceramic cartridges was when I first started DJ-ing, first off into a WEM PA (solid state amp) and then through a Selmer 200W Valve amp driving a pair of Orange 4 x 12 columns. The latter setup, as I recall, really did sound amazing. I have some pix of that setup somewhere.

[willbewill]

I'm with Tony on this, when I had a mobile disco back in early 70s I used ceramic cartridges directly into a Carlsbro 200w valve pa and they sounded fabulous, maybe not strictly hifi but great to dance to.

[williamsunique]

I'm with Tony on this, when I had a mobile disco back in early 70s I used ceramic cartridges directly into a Carlsbro 200w valve pa and they sounded fabulous, maybe not strictly hifi but great to dance to.

Thank you for your comment, but I think you have missed the point of this circuit.  Yes I agree that a valve amplifier has a high input impedance and therefore does not require this circuit.  The circuit is designed for a solid state amplifier, not a valve amplifier.  This is made clear in my description of it.  Quote:- "It is designed to plug into the line input of a solid state amplifier."

Paul.

[willbewill]

Sorry Paul, brain befuddled here, because of a nasty bout of flu like virus.

[floppybootstomp]

What Malcolm said, me too Paul.

I'm just recovering from a cold/virus that was quite nasty too, almost over it  now but it lasted a good month, not good.

[nescafetrinker]

Sorry, (don't  want to be a pedant!)  a gain of 0 would give no output.

Sorry (don´t want to be a pedant) a gain of 0 means: no amplification of the signal (is has not gained anything)!
So,the signal is passed through unaltered in strength, but not cut off as you seem to understand the statement.

[williamsunique]

What Malcolm said, me too Paul.

I'm just recovering from a cold/virus that was quite nasty too, almost over it  now but it lasted a good month, not good.

I wish you and Malcolm a quick recovery.  We here too have suffered earlier from a virus.  It started on New Years Eve and we could hardly get out of bed for a few days.  I am still not feeling 100%.  Some warmer weather would be the tonic I need.

Paul

[wer]

Schweppes might be easier to find 

[williamsunique]

I have just been looking at some circuits of modern day valve amplifiers and they tend to have a low impedance line input.  Typically a resistance of 100K.  I have in the past serviced vintage valve amplifiers and these were equipped with a dedicated crystal / ceramic phono input, sometimes with a potentiometer to alter impedance. This potentiometer would have catered for both the higher level output crystal cartridges and the lower level ceramic cartridges.  Probably variable from 1M to 10M.
My ceramic phono pre-amp circuit would therefore correctly match the line input impedance (typically 100K) of these modern day valve amplifiers.  I would therefore conclude that unless the line input of an amplifier is of high impedance, then when using a ceramic cartridge into this line input, my phono pre-amp will be of benefit.  

Paul  

[williamsunique]

Schweppes might be easier to find 

Shhhh!


Paul

[colin]

Hi Paul,

I agree, the better ceramic cartridges in good condition can sound lively and full bodied into the right input and lousy into standard line inputs.  Your circuit is a great idea for diy folk to try.  

Most amps of the early 70s had a dedicated ceramic input.  I use the Quad 33 pre-amp (the phono input has a ceramic option) for ceramic cartridges - including the Sonotone and Deram.