Ceramic cartridge to phono preamp

the thin end of the wedge
moretti
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Ceramic cartridge to phono preamp

Post by moretti » 30 Jan 2019 14:08

Hi,
before starting, I do know how ceramic quality is different than magnetic cartridge. I also own a Sony PS-HX500 and yes, I'm thinking about upgrading the cartridge to a VM540ML.

Having said that, lets move on to the reason I created this post
I want to connect a ceramic cartridge to a mm phono preamp, but I'm really not good at audio electronics.

Ceramic to magnetic adapter.jpg
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Ceramic impedance matching.jpg
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Ceramic coupler.png
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The 1k solution looks nice, and the analysis found here http://pspatialaudio.com/45rpm.htm looks very detailed, but I was wondering what would be the "best". Even though the sound quality won't be good, I still want to give it a try.

Back story: my aunt gave me a very old Televa T-314 which uses a Tetrad 1 or 2 (the guy who sold the replacement said it was 2, but the box says 1) cartridge with a T5HS stylus. These record players were made by Televa and then licensed to Columbia, which made the same model with different mechanics inside (mainly a different, plastic, speed selector). I can tell Columbia made a cheaper version because I bought their model too and every single different piece they did is sub-par compared to the Televa player. To be honest these are not very good quality (neither of them), but they do have 16 and 78 speed selectors, which my Sony doesn't have. And they can play just fine at 3g, which is the same weight recommended by Sony for their turntable.

Thank you for reading this far

Coffee Phil
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Re: Ceramic cartridge to phono preamp

Post by Coffee Phil » 30 Jan 2019 22:28

Hi Moretti,

Welcome to the forum.

First off while ceramic cartridges are typically inferior to magnetics, they are not necessarly awful.

Now on to how to use them.

The response of a ceramic cartridge is proportional to amplitude, while that of a magnetic is proportional to velocity. Also the voltage output of a ceramic cartridge @ 1 kHz is apout 30 to 40 dB greator than that of a magnetic cartridge. The main purpose of a magnetic phono stage is to convert the velocity response of a magnetic cartridge to an amplitude response similar to a ceramic and to raise the voltage level of the signal. The magetic phono stage also has the proper recording equalization (RIAA).

The first and fourth circuits which you posted are suitable to attenuate the output of the ceramic to the proper level for a magnetic phono stage as well as providing the differenciating function to change amplitude output to velocity output.

The second and third circuits will provide the attunation, however they will not properly execute the differenciating.

The classic way to use a ceramic cartridge is to run it into a flat gain amplifier with a very high input impedance. The first circuit will provide the high impedance load which the ceramic “expects”. The forth circuit will place a low impedance load on the cartridge. Other than that it is similar to the first circuit in that it uses the internal ~1000 pF capacitor of the cartridge as the differenciating capacitor in the same manor as the 100 pF cap in the first circuit.

Phil
moretti wrote:
30 Jan 2019 14:08
Hi,
before starting, I do know how ceramic quality is different than magnetic cartridge. I also own a Sony PS-HX500 and yes, I'm thinking about upgrading the cartridge to a VM540ML.

Having said that, lets move on to the reason I created this post
I want to connect a ceramic cartridge to a mm phono preamp, but I'm really not good at audio electronics.


Ceramic to magnetic adapter.jpg
Ceramic impedance matching.jpg
Ceramic coupler.png

The 1k solution looks nice, and the analysis found here http://pspatialaudio.com/45rpm.htm looks very detailed, but I was wondering what would be the "best". Even though the sound quality won't be good, I still want to give it a try.

Back story: my aunt gave me a very old Televa T-314 which uses a Tetrad 1 or 2 (the guy who sold the replacement said it was 2, but the box says 1) cartridge with a T5HS stylus. These record players were made by Televa and then licensed to Columbia, which made the same model with different mechanics inside (mainly a different, plastic, speed selector). I can tell Columbia made a cheaper version because I bought their model too and every single different piece they did is sub-par compared to the Televa player. To be honest these are not very good quality (neither of them), but they do have 16 and 78 speed selectors, which my Sony doesn't have. And they can play just fine at 3g, which is the same weight recommended by Sony for their turntable.

Thank you for reading this far

moretti
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Re: Ceramic cartridge to phono preamp

Post by moretti » 30 Jan 2019 23:24

wow, that was a very good explanation. Thank you very much. I will use the first circuit then. I was planning to connect it to a RIAA phono preamp, but before doing so I will try to use a buffer like Musical Fidelity X-10D Tube, which doesn't compensate the RIAA curve, and see how it goes.

Again, thank you for the quick and detailed response.

smee4
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Re: Ceramic cartridge to phono preamp

Post by smee4 » 31 Jan 2019 03:15

Coffee Phil wrote:
30 Jan 2019 22:28
Hi Moretti,

Welcome to the forum.

First off while ceramic cartridges are typically inferior to magnetics, they are not necessarly awful.

Now on to how to use them.

The response of a ceramic cartridge is proportional to amplitude, while that of a magnetic is proportional to velocity. Also the voltage output of a ceramic cartridge @ 1 kHz is apout 30 to 40 dB greator than that of a magnetic cartridge. The main purpose of a magnetic phono stage is to convert the velocity response of a magnetic cartridge to an amplitude response similar to a ceramic and to raise the voltage level of the signal. The magetic phono stage also has the proper recording equalization (RIAA).

The first and fourth circuits which you posted are suitable to attenuate the output of the ceramic to the proper level for a magnetic phono stage as well as providing the differenciating function to change amplitude output to velocity output.

The second and third circuits will provide the attunation, however they will not properly execute the differenciating.

The classic way to use a ceramic cartridge is to run it into a flat gain amplifier with a very high input impedance. The first circuit will provide the high impedance load which the ceramic “expects”. The forth circuit will place a low impedance load on the cartridge. Other than that it is similar to the first circuit in that it uses the internal ~1000 pF capacitor of the cartridge as the differenciating capacitor in the same manor as the 100 pF cap in the first circuit.

Phil

I am puzzled by that last circuit. In my experience, running a ceramic cart into such a low impedance will result in a large loss of bass response. That's what circuits 2 and 3 are attempting to correct by presenting a high impedance to the cart, and using a voltage divider to reduce the voltage to what is acceptable, but they show the output going to a phono preamp, presumably with RIAA eq, so the result will be too much bass.

I have tried the circuit in #1 but was not happy with the sound. I prefer now to use a high impedance buffer/preamp with flat response, into a normal line input as you suggest is the 'classic' way, I find it best.

Coffee Phil
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Re: Ceramic cartridge to phono preamp

Post by Coffee Phil » 31 Jan 2019 07:39

Hi Moretti,

I have used both the first and fourth of those circuits into a magnetic phono stage with good results. The up-side of that approach is that the magnetic phono stage will address the points of inflection at 500 Hz and 2120 Hz in the RIAA curve.

The high impedance buffer between the cartridge and an AUX input is also valid however the playback will be strictly constant amplitude unless the 500 Hz and 2100 Hz points of inflection are addressed inside the cartridge itself. One thing to consider is the input resistance of the buffer stage. Assuming a capacatance of 1000 pF in the cartridge, to get a 20 Hz low frequency -3 dB point will require an input resistance of ~ 8 megohms for the buffer.

Phil
moretti wrote:
30 Jan 2019 23:24
wow, that was a very good explanation. Thank you very much. I will use the first circuit then. I was planning to connect it to a RIAA phono preamp, but before doing so I will try to use a buffer like Musical Fidelity X-10D Tube, which doesn't compensate the RIAA curve, and see how it goes.

Again, thank you for the quick and detailed response.

Coffee Phil
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Re: Ceramic cartridge to phono preamp

Post by Coffee Phil » 31 Jan 2019 08:08

Hi smee4,

In the fourth circuit what you have is the ~ 1000 pF series capacitance of the ceramic cartridge and the 1 k Ohm resistor acting as a differerentor in like manor to the 100 pF cap and 47 k Ohm of the magnetic phono stage in the first circuit. The concept is that the first derivitive of position vs. time is velocity. Ths changes the constant amplitude response of the ceramic cartridge to constant velocity like a magnetic.

The second and third of those circuits are not all that useful as they do not provide a high enough load resistance for a ceramic to be constant amplitue over the audio range so they are not useful for a non equalized mic input and they won’t make an acceptable differentiator to use with a magnetic phono stage.

Phil

smee4 wrote:
31 Jan 2019 03:15
Coffee Phil wrote:
30 Jan 2019 22:28
mnb

I am puzzled by that last circuit. In my experience, running a ceramic cart into such a low impedance will result in a large loss of bass response. That's what circuits 2 and 3 are attempting to correct by presenting a high impedance to the cart, and using a voltage divider to reduce the voltage to what is acceptable, but they show the output going to a phono preamp, presumably with RIAA eq, so the result will be too much bass.

I have tried the circuit in #1 but was not happy with the sound. I prefer now to use a high impedance buffer/preamp with flat response, into a normal line input as you suggest is the 'classic' way, I find it best.

vanakaru
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Re: Ceramic cartridge to phono preamp

Post by vanakaru » 31 Jan 2019 08:14

Here is extensive discussion about the topic
viewtopic.php?t=82160&start=45
I use Sonotone adapter "network for magnetic input"(500pF, 68K, 10K) with great sound. I tried some others, but this sounds the best - not only Sonotone 9TA but with BRS SC5M and Decca Deram as well.
velocitone.jpg
(229.93 KiB) Downloaded 127 times

moretti
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Re: Ceramic cartridge to phono preamp

Post by moretti » 31 Jan 2019 18:58

Coffee Phil wrote:
31 Jan 2019 07:39
Hi Moretti,

I have used both the first and fourth of those circuits into a magnetic phono stage with good results. The up-side of that approach is that the magnetic phono stage will address the points of inflection at 500 Hz and 2120 Hz in the RIAA curve.

The high impedance buffer between the cartridge and an AUX input is also valid however the playback will be strictly constant amplitude unless the 500 Hz and 2100 Hz points of inflection are addressed inside the cartridge itself. One thing to consider is the input resistance of the buffer stage. Assuming a capacatance of 1000 pF in the cartridge, to get a 20 Hz low frequency -3 dB point will require an input resistance of ~ 8 megohms for the buffer.

Phil
You convinced me. I'm going to hook it to a behringer pp400 + the two 100pf caps.

thanks!

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Re: Ceramic cartridge to phono preamp

Post by Spinner45 » 31 Jan 2019 19:10

vanakaru wrote:
31 Jan 2019 08:14
Here is extensive discussion about the topic
viewtopic.php?t=82160&start=45
I use Sonotone adapter "network for magnetic input"(500pF, 68K, 10K) with great sound. I tried some others, but this sounds the best - not only Sonotone 9TA but with BRS SC5M and Decca Deram as well.

velocitone.jpg
Basically, the Sonotone Network is what is required, however, I've found that changing the 10K resistor to 8.2K or even 6.8K is needed for higher output ceramics.

vanakaru
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Re: Ceramic cartridge to phono preamp

Post by vanakaru » 31 Jan 2019 19:33

Spinner45 wrote:
31 Jan 2019 19:10
vanakaru wrote:
31 Jan 2019 08:14
Here is extensive discussion about the topic
viewtopic.php?t=82160&start=45
I use Sonotone adapter "network for magnetic input"(500pF, 68K, 10K) with great sound. I tried some others, but this sounds the best - not only Sonotone 9TA but with BRS SC5M and Decca Deram as well.

velocitone.jpg
Basically, the Sonotone Network is what is required, however, I've found that changing the 10K resistor to 8.2K or even 6.8K is needed for higher output ceramics.
Good, I'll try. Some of them(BSR) are a bit too much.

Coffee Phil
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Re: Ceramic cartridge to phono preamp

Post by Coffee Phil » 31 Jan 2019 19:40

Hi moretti,

I believe it will work for you. As you may know I posted that circuit a while back. I wont claim that I designed it, as I got it from the schematic of my Harmon Kardon Citation IV.

gallery/image/23832/medium

Look at the circled part of the schematic. It is similar in concept to the Sonotone circuit with a larger cap and 10 k Ohm across the 47 k Ohm of the phono stage. The Sonotone is half way between the first and fourth circuit which you posted. The Sonotone also has a 68 k resistor across the 500pF cap, I would guess to boost bass, however that will bring the internal 1000 pF cap of the cartridge into play. Once you build the box you can try both sets of values to see which you like best.

Phil


moretti wrote:
31 Jan 2019 18:58
Coffee Phil wrote:
31 Jan 2019 07:39
Hi Moretti,

I have used both the first and fourth of those circuits into a magnetic phono stage with good results. The up-side of that approach is that the magnetic phono stage will address the points of inflection at 500 Hz and 2120 Hz in the RIAA curve.

The high impedance buffer between the cartridge and an AUX input is also valid however the playback will be strictly constant amplitude unless the 500 Hz and 2100 Hz points of inflection are addressed inside the cartridge itself. One thing to consider is the input resistance of the buffer stage. Assuming a capacatance of 1000 pF in the cartridge, to get a 20 Hz low frequency -3 dB point will require an input resistance of ~ 8 megohms for the buffer.

Phil
You convinced me. I'm going to hook it to a behringer pp400 + the two 100pf caps.

thanks!

moretti
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Re: Ceramic cartridge to phono preamp

Post by moretti » 31 Jan 2019 21:10

before doing it I have one last question.

The Televa does not seem to have a phono output from factory. From what I can tell.. it does have two mono jacks meant for recording.
I took the time to also get the original manuals from these turntables, and it says it's meant for recording, and the picture shows something that resembles an amp, but I plugged that directly into a line input and only got distortion until I lowered the volume a lot, and the music was mostly noise anyway. What kind of recording devices did they use back then? What kind of device was supposed to be plugged in that "Record" mono jacks?

(it also has an FM input, which surprised me)

Can I add the phono connection straight from the tone arm and cartridge? or do I have to do anything else/take it from somewhere else?

I disassembled the turntable and confirmed that these two ouput jacks are not directly connected to the cartridge.

Thank you

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Re: Ceramic cartridge to phono preamp

Post by vanakaru » 31 Jan 2019 22:28

I would take direct from tonearm wires. You can put the adapter network there as well. I have it inside the head-shell for one instance and other between TT RCA out cable and phono pre in.

moretti
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Re: Ceramic cartridge to phono preamp

Post by moretti » 31 Jan 2019 23:18

yes, I was planning to reuse the mono jacks and include the ceramic caps inside them, so I would just need to plug the preamp to the "Record" jacks without anything else. But I was curious about what was the original purpose of those, since there seems to be a few mega ohms between them and the cartridge I assume they were actually outputing something that went through the included preamp

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Re: Ceramic cartridge to phono preamp

Post by Spinner45 » 31 Jan 2019 23:55

moretti wrote:
31 Jan 2019 23:18
yes, I was planning to reuse the mono jacks and include the ceramic caps inside them, so I would just need to plug the preamp to the "Record" jacks without anything else. But I was curious about what was the original purpose of those, since there seems to be a few mega ohms between them and the cartridge I assume they were actually outputing something that went through the included preamp
Show a schematic of this unit, because unless I can read it, I can't even speculate on anything.

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