Ceramic cartridge to Aux line level input -- proper EQ and bass

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empireboy
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Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 19 Jan 2020 21:26

What modification would one have to make to the circuitry of the aux / line in section of a preamp in order for a ceramic phono cartridge to have proper equalization and bass response?

(Existing threads on this topic deal with modifying a preamp phono circuit, this is focused on aux / line level type inputs only.)

lenjack
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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by lenjack » 19 Jan 2020 22:34

Not sure, but I think an ideal ceramic cartridge would need no correction.

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 19 Jan 2020 22:46

For clarification, I'm referring to a solid state aux / line level type input.

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by wolfie62 » 20 Jan 2020 13:43

You would need the proper gain ahead of the AUX input, as well as whatever equalization is required.

So you need to research what the requirements are for your ceramic cartridge. Do you know what they are?

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by lenjack » 20 Jan 2020 15:06

Seems there's more to this than meets the eye. Found this https://rec.antiques.radio-phono.narkiv ... ualization. You'll find a lot if you google.

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 20 Jan 2020 15:21

wolfie62 wrote:
20 Jan 2020 13:43
You would need the proper gain ahead of the AUX input, as well as whatever equalization is required.

So you need to research what the requirements are for your ceramic cartridge. Do you know what they are?
Sonotone 9TA.

I found this online:

http://www.roger-russell.com/sonopg/velocitone.jpg

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by vanakaru » 20 Jan 2020 15:51

I don't know why you insist on plugging it into line. It does work rather well when phono pre is used with a cap and two resistors adapter(network for magnetic input) and you get proper RIAA EQ. You need to match impedance of line 10K with Sonotone. If I remember right it needs some MegOhm resistors across the Line Input.

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by lenjack » 20 Jan 2020 16:01

Right. If you Google, you'll find schematics for both aux and phono ceramics.

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 20 Jan 2020 16:58

vanakaru wrote:
20 Jan 2020 15:51
I don't know why you insist on plugging it into line. It does work rather well when phono pre is used with a cap and two resistors adapter(network for magnetic input) and you get proper RIAA EQ. You need to match impedance of line 10K with Sonotone. If I remember right it needs some MegOhm resistors across the Line Input.
Let me explain:

1. I installed a Sonotone 9TA ceramic cartridge on a changer that works with a Zenith solid state console.
2. Per the Zenith schematic, the "Phono" input appears to be line level with only a 2.2 meg resistor (see below)
3. This input was tailored for Zenith's "in house" MicroTouch 2G ceramic cartridge.
4. I don't know the exact specs of the Zenith cartridge 2G cartridge

https://i.ibb.co/9wWpK15/phono.jpg

Questions:

1. Is the 2.2 meg resistor in the schematic above designed to properly EQ the Zenith cartridge?
2. Or is the 2.2 meg resistor only a pad to attenuate (reduce) the phono signal to make the relative volume more consistent with perhaps the FM signal, for example, when changing inputs? In other words, does the 2.2 meg resistor have no impact on EQ of a ceramic phono cartridge?
3. If it does serve as EQ, would a different resistor value be advisable for the Sonotone 9TA? Would capacitance need to be added per the circuit below or would a resistor suffice? Again this is solid state.
4. Is the "Network for Ceramic Input" below for an Aux line level input in a solid state preamp (vs tube)?

http://www.roger-russell.com/sonopg/velocitone.jpg

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by Bandit127 » 20 Jan 2020 18:24

On the graph, the "Network for Ceramic Input" shows the 3.3 meg as an impedence matching resistor for the tube amp input. You won't need that, RCAs have much lower impedence (10k Ohms) than tubes.

The 600 µµF cap and 1.0 meg in series are probably there for dropping high frequency (RF interference) to ground.

The 100 µµF seems optional and possibly capacitance matching for the cable.

Back in the day (and I was there) the ceramic leads would go to an Aux or Tape RCA (actually I remember a 5 pin DIN was more common but that was also a line input).

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 20 Jan 2020 21:09

https://i.ibb.co/9wWpK15/phono.jpg

What does the 2.2 meg resistor due in the solid state schematic above?

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by Coffee Phil » 20 Jan 2020 22:37

Hi Empireboy,

A ceramic cartridge is amplitude responding vs. velocity responding as magnetic cartridges are. Most of what magnetic stages do is to convert the velocity responding signal to and amplitude responding signal. That amounts to a 6 dB slope over the audio range. Actually there are points of inflection at 500 Hz and 2120 Hz but that is second order. A pure amplitude responding system is pretty acceptable. That said, a ceramic cartridge should sound fine into an AUX input. Back in the tube days it usually was as AUX inputs were typically ~500 k-Ohms. >1 meg-ohm is better but 500 K is sort of acceptable. AUX inputs today are typically ~10 k Ohm. The model of a ceramic cartridge has ~ a 1000 pF capacitor in series with it’s output. The low inpedance inputs will kill the low frequency response. If you get the input impedance above 500 K-ohms, the flat frequency response of the AUX input should be fine.

You can precede the AUX input with a cathode follower or unity gain buffer made with a FET op-amp and things should also be fine.

Alternately you can make a simple passive network to convert the ceramic to velocity response and go into a RIAA magnetic input. The network is just a 100 pF capacitor in series with the 47 k-ohm magnetic input. Less aggravation than trying to raise the input of the AUX and you get the points of inflection at 500 and 2120 Hz for true RIAA EQ.

Phil
empireboy wrote:
19 Jan 2020 21:26
What modification would one have to make to the circuitry of the aux / line in section of a preamp in order for a ceramic phono cartridge to have proper equalization and bass response?

(Existing threads on this topic deal with modifying a preamp phono circuit, this is focused on aux / line level type inputs only.)

empireboy
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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by empireboy » 20 Jan 2020 22:55

Coffee Phil wrote:
20 Jan 2020 22:37
Hi Empireboy,

A ceramic cartridge is amplitude responding vs. velocity responding as magnetic cartridges are. Most of what magnetic stages do is to convert the velocity responding signal to and amplitude responding signal. That amounts to a 6 dB slope over the audio range. Actually there are points of inflection at 500 Hz and 2120 Hz but that is second order. A pure amplitude responding system is pretty acceptable. That said, a ceramic cartridge should sound fine into an AUX input. Back in the tube days it usually was as AUX inputs were typically ~500 k-Ohms. >1 meg-ohm is better but 500 K is sort of acceptable. AUX inputs today are typically ~10 k Ohm. The model of a ceramic cartridge has ~ a 1000 pF capacitor in series with it’s output. The low inpedance inputs will kill the low frequency response. If you get the input impedance above 500 K-ohms, the flat frequency response of the AUX input should be fine.

You can precede the AUX input with a cathode follower or unity gain buffer made with a FET op-amp and things should also be fine.

Alternately you can make a simple passive network to convert the ceramic to velocity response and go into a RIAA magnetic input. The network is just a 100 pF capacitor in series with the 47 k-ohm magnetic input. Less aggravation than trying to raise the input of the AUX and you get the points of inflection at 500 and 2120 Hz for true RIAA EQ.

Phil
empireboy wrote:
19 Jan 2020 21:26
What modification would one have to make to the circuitry of the aux / line in section of a preamp in order for a ceramic phono cartridge to have proper equalization and bass response?

(Existing threads on this topic deal with modifying a preamp phono circuit, this is focused on aux / line level type inputs only.)
Hi Coffee Phil,

The solid state Zenith console doesn't have an RIAA input. The existing phono input is essentially a line input meant to work best with a Zenith 2G floating cartridge, not a Sonotone 9TA. The preamp does have a pre-installed 2.2 meg resistor at the input. Unclear to me if it's just lowering the signal or EQ'ing it. See below.

https://i.ibb.co/9wWpK15/phono.jpg

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Re: Ceramic cartridge to Aux line level input -- proper EQ and bass

Post by Coffee Phil » 21 Jan 2020 04:13

Hi Empireboy,

There is not enough of that schematic for me to see what is going on.
Are you replacing a piezzoelectric pickup in a Zenith console with a newer one?
If so I am pretty sure Zenith provided the correct load.

Phil




empireboy wrote:
20 Jan 2020 22:55
Coffee Phil wrote:
20 Jan 2020 22:37
Hi Empireboy,

A ceramic cartridge is amplitude responding vs. velocity responding as magnetic cartridges are. Most of what magnetic stages do is to convert the velocity responding signal to and amplitude responding signal. That amounts to a 6 dB slope over the audio range. Actually there are points of inflection at 500 Hz and 2120 Hz but that is second order. A pure amplitude responding system is pretty acceptable. That said, a ceramic cartridge should sound fine into an AUX input. Back in the tube days it usually was as AUX inputs were typically ~500 k-Ohms. >1 meg-ohm is better but 500 K is sort of acceptable. AUX inputs today are typically ~10 k Ohm. The model of a ceramic cartridge has ~ a 1000 pF capacitor in series with it’s output. The low inpedance inputs will kill the low frequency response. If you get the input impedance above 500 K-ohms, the flat frequency response of the AUX input should be fine.

You can precede the AUX input with a cathode follower or unity gain buffer made with a FET op-amp and things should also be fine.

Alternately you can make a simple passive network to convert the ceramic to velocity response and go into a RIAA magnetic input. The network is just a 100 pF capacitor in series with the 47 k-ohm magnetic input. Less aggravation than trying to raise the input of the AUX and you get the points of inflection at 500 and 2120 Hz for true RIAA EQ.

Phil
empireboy wrote:
19 Jan 2020 21:26
What modification would one have to make to the circuitry of the aux / line in section of a preamp in order for a ceramic phono cartridge to have proper equalization and bass response?

(Existing threads on this topic deal with modifying a preamp phono circuit, this is focused on aux / line level type inputs only.)
Hi Coffee Phil,

The solid state Zenith console doesn't have an RIAA input. The existing phono input is essentially a line input meant to work best with a Zenith 2G floating cartridge, not a Sonotone 9TA. The preamp does have a pre-installed 2.2 meg resistor at the input. Unclear to me if it's just lowering the signal or EQ'ing it. See below.

https://i.ibb.co/9wWpK15/phono.jpg

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