Bass response from ceramic cartridges

[Growlerman]

Sorry for the silly question but how good is the bass produced by a ceramic cartridge?
The reason I ask is that I'm working on a 70s music centre that is fitted with a BSR sch12m cartridge. Having been used to magnetic cartridges the bass produced by the 12m is rather weak. I am using the same headphones in this comparison.

Thanks
Dave

[Herald1360]

Within reason, the amount of bass from a ceramic cartridge depends on how well the amplifier is designed to load it correctly. Cheap solid state amps will likely be a compromise since more complex circuitry is needed to get the high input impedance required as a starting point. Valve amps start from a better place but may well be deliberately short on bass response simply to avoid obvious hum problems.

Feeding that cartridge direct into a decent '50s valve preamp/amp combo would show what it was capable of achieving, as would building a small IC matching buffer for the aux input of a modern amp.

[lesmw0sec]

Any crystal type (and this probably includes ceramic) has the equivalent circuit of a capacitor, so that a resistive load will cause the combination to act as a first order filter (bass-cut). Conversly, shunting the cartridge output should cause a reduction in total signal, rather than top-cut.

[Nickthedentist]

Bass response can be very good, though as Julie and Les say, the amp can attenuate.

I had an early 1970s Portadyne stereo, a cheap and cheerful affair with a BSR cartridge and autochanger and which had very little bass. It wasn't the cartridge, so I assume the amp was the culprit.

What is the music centre?

[paulsherwin]

There is nothing inherently poor about the bass response of ceramic cartridges. The BBC used a lot of Decca Deram ceramic carts in their studio decks.

As others have said, they need a high input impedance of at least 1M. This is a bit tricky to achieve with bipolar transistors (though it can be done) so when cheap transistor music centres became common they often presented the cart with less than perfect loading. The argument was that this didn't matter if the bass response of the amp and speakers was poor anyway.

[Growlerman]

Originally Posted by Nickthedentist

What is the music centre?

Hi Nick

It's a Wye 802 music centre(well radio and phono). I wondered if I've been spoilt by magnetic cartridges.
I'm know very little about the quality of Wye Audio products as I understand that they were sold through mail order catalogues.

[paulsherwin]

Wye weren't an upmarket brand, so I wouldn't expect too much.

[Growlerman]

Thanks Paul that clears things up.

Dave

[Edward Huggins]

Your BSR SC12M (not SCH), whilst not in the same class as a Decca DERAM, is capable of a good bass response. I also agree that WYE products were rather budget built, especially if you are playing it through the type of small bookshelf speakers normally supplied with these kind of "seperates" units. If so, try a pair of larger speakers and you might well be surprised by the sound it makes.

[Studio263]

A ceramic cartridge is a displacement sensor, its output depends on how far the stylus moves. Connected to an amplifier with a high enough input impedance and ignoring other forms of leakage, it could theoretically have a flat response down to DC and be able to detect a static offset of the stylus assembly.

A magnetic cartridge is a velocity sensor, its output is dependant on how quickly a piece of magnetic material passes by a coil of wire. Therefore, output falls with frequency and the output is zero with no stylus movement, no matter how the connected amplifier is designed.

In practice equalisation is used to make the two types give broadly similar results (mechanical for ceramics, electronic for magnetics). Of the two, the ceramic is initially more promising for high fidelity applications, as the early work of Philips demonstrated. The stiffness of the ceramic elements is the limiting factor, you need to take a lot of mechanical effort out of the record / stylus interface to modulate the sensing element sufficiently to make good use of it. This puts pressure on the design of the arm. Arms for hi-fi tend to favour high(ish) compliance cartridges, which ceramics are not. Bass energy is lost if too much of the movement of the stylus is lost rattling the headshell about, which is what can end up happening.

Interestingly, there was a strain gauge based cartridge available from Soundsmith recently that was also a displacement sensor, just like a ceramic. The accompanying special pre-amplifier (a strain gauge needs an excitation voltage as well, so you couldn't just plug it into the back of your battered NAD 3020!) had a display in the form of a 'V' pattern of LEDs. This showed the loading of each of the groove faces of the record, allowing things like anti-skating to be set very accurately. Being a displacement sensor, very little in the way of equalisation was necessary and at the demonstration I heard the results were outstanding. Sadly it doesn't seem to have caught on though.

The Decca Deram is an excellent 'hi-fi' ceramic cartridge which gives fine results if you get the amplifier match right. They are cheap and worth experimenting with if this subject interests you. Garrard made a special deck to match it where the cartridge plugs straight into the end of the arm (a poor man's B&O?) called the Deccadec(k?), also cheap and a good place to start. Modern FET op amps would make a fine high impedance buffer stage with perhaps a little gain - the Deram's output is not high for a ceramic - to match into the 50k input loading of modern amplifiers. A truly exotic and technically different turntable for pocket money? I may even give it a go myself!

[Nickthedentist]

Thanks for your time explaining that, Tim, much appreciated.

I think the Deccadec (and the FFSS version) was essentially a modified version of your favourite "toy" turntable, the SP25: https://www.vintage-radio.net/forum/...6&postcount=29

[PsychMan]

Could the rubber suspension in this cartridge have hardened and produced this effect I wonder?

[John10b]

Slightly off course but if any one is interested I’ve just opened an old Sonotone 8T Cartridge and took some pictures, I’m unable to post them to the forum ( I’m using an iPad and have tried) so if any one would like to see them, and perhaps put them on forum , please send me pm etc.
Cheers
John

[Growlerman]

Originally Posted by PsychMan

Could the rubber suspension in this cartridge have hardened and produced this effect I wonder?

I swapped out the 12M for a good 12H that I have and there was no difference in the bass response.

[Nuvistor]

John, PM sent, see if I can post the photos.

[John10b]

Frank pm and pics sent.
Cheers
John

[Growlerman]

Originally Posted by PsychMan

Could the rubber suspension in this cartridge have hardened and produced this effect I wonder?

I swapped out the 12M for a good 12H that I have and there was no difference in the bass response.

[Nuvistor]

Photos of the 8T cartridge thanks to John.

[Edward Huggins]

There will not be any noticeable difference.

[Nuvistor]

More photos of the 8T cartridge.