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Turntable Cartridge Output Voltage with Vintage Receivers

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Yes - I liked the look of the puffin. Digital settings for gain - perfect for the cartridge swapper.
I like the fact you can somewhat remove clicks/pops using the Magic feature. Reviews on this seem pretty good. But I also like the PJL reviews.
 
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So in looking at various phono pre-amps I'm trying to understand how you work them. Some have solid state, others have tubes. I see some with the dip switches. How do you configure it to work with your cart? What options/settings does a phono pre have to have? I will most likely keep the pre with the Soundsmith exclusively so I'm not sure I need one that does MM and MC.

I found an article that explains things a bit further:

Soundsmith:
Though the SMMC1 is intended for use with an MM phono preamp, its specified output is a relatively moderate >2.12mV at 5cm/s. (A typical MM cartridge's output is 4.5mV.)

Recommended resistive loading is 47k ohms, while the recommended capacitive loading is equal to or greater than 400pF or greater.

Nagaoka MP-500;

Recommended load resistance: 47 kOhm
Recommended load capacitance: 150-200pF

What settings would be used on a phono pre to provide these figures? And as far as tubes vs SS, what is the advantage to either?
 
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JeffS7444

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What settings would be used on a phono pre to provide these figures? And as far as tubes vs SS, what is the advantage to either?
Tube advantages: Some people enjoy fussing with tubes, that's all. Can be prone to noise and microphonics. IMO, tube rolling is pretty much a waste of time.

The effects of capacitive loading on an MM cartridge are measurable, but being able to distinguish the differences by hearing alone is another matter. Your phono leads easily add 150 pF, while the preamp itself could account for another 150. Main reason for wanting to really fine-tune these things is for the intellectual stimulation, because unless you're way, way off, it's unlikely that you'll perceive any difference.
 

rongon

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I use the rule of thumb that one should never have to be above 60% of full scale on their amp volume because distortion starts to become a factor on many amps.

Sorry if this comes off as overly pedantic, but I don't believe this statement is actually correct and I wanted to clear up any misconceptions.

There should be no correlation between the physical position of the volume control knob and distortion except how it affects the signal level that reaches the amplifier circuit input. Perhaps noise, but not distortion.
The way this works is this:
  1. Let's say you have an amplifier that clips with 2V input, and that it has gain of 20X (26dB). This amp will clip with a source voltage of 100mV driving it (2V/20 = 0.1V).
  2. Let's also say you find the perfect listening volume is attained with an average of 1mV driving the amplifier. That will be amplified by 20X to 20mV average, allowing another 4X of amplification (12dB of 'headroom') .
EXAMPLE A:
Let's say audio source A has an average output level of 0.1V (100mV). This source has 100X more output voltage than necessary to clip the amplifier driving the speakers. You will need to put a volume control on the input and turn it down enough to attenuate the input by 100X, or -40dB.

Let's say that puts the volume control at exactly 12 o'clock in its rotation, or 50% (half-way up).

EXAMPLE B:
Now, let's say audio source B has an average output level of 0.01V (10mV). You will need to attenuate this signal less to take it down to our sweet spot of 1mV average signal to the amplifier circuit's input. The signal will need to be attenuated by 10X (-20dB) from 10mV average down to 1mV average.

Let's say that means the volume control will now be at 3 o'clock in its rotation, or 75% (three-quarters of the way up).

In both cases, Ex. A and Ex. B, we've used the volume control to attenuate the incoming average signal level to 1mV.
It does not matter at what position the volume control is set. What matters is the signal level applied to the input of the amplifier.

If an amplifier distorts with even a tiny signal on it just because you turn its volume control up to 75%, then there is something very wrong with that amplifier.
 

rongon

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Tube advantages: Some people enjoy fussing with tubes, that's all. Can be prone to noise and microphonics. IMO, tube rolling is pretty much a waste of time.

The effects of capacitive loading on an MM cartridge are measurable, but being able to distinguish the differences by hearing alone is another matter. Your phono leads easily add 150 pF, while the preamp itself could account for another 150. Main reason for wanting to really fine-tune these things is for the intellectual stimulation, because unless you're way, way off, it's unlikely that you'll perceive any difference.

I agree about tube advantages. Also, another problem with almost all tube RIAA preamps is that they have very high input capacitance (200pF for a 12AX7/ECC83) and then you have to add the capacitance of the tonearm wiring and interconnect cables. It can easily reach 400pF. That will put an up to 8dB spike in the response of some MM cartridges centered at around 8kHz (the amplitude and frequency of that peak depending on the inductance and resistance of the cartridge, and the load capacitance of cables/preamp input). You will hear that. Some will like it. Some will not. Some will not notice. (Most people will not care :D !!)

Grado (moving iron) and high output moving coil cartridges (e.g., Denon DL110) will not have this problem because they don't have the high coil inductance/resistance of a moving magnet cartridge.

In the old days, Stanton, Pickering, Shure cartridges used this LCR resonance to compensate for the falling frequency response of most MM cartridge assemblages, so they would recommend much higher load capacitances like 450pF. Audio Technica et al no longer do this. They design their cartridges to work into a 150pF (or thereabouts) load, or 3X lower. That's a pretty big difference.

I believe this is why I could never get my Audio Technica AT-VM95 cartridge to sound really good through my 12AX7-based preamp, whereas my Shure M35X with Jico elliptical stylus actually sounded pretty good (although not to my taste). I figure the input capacitance of that 12AX7 preamp is about 200pF, possibly 250pF. However, after building an Elliott Sound Products Project-06 opamp-based RIAA preamp, I'm now much happier with the AT cart. I have zero added load capacitance, and I figure the input capacitance of the opamp is on the order of 10 to 15pF. The tonearm wire adds 30pF, and my phono cable adds 80pF, so the total load C is very close to the AT recommended 150pF. And guess what? The AT cart sounds far better through the ESP P-06, while the M35X sounds darker (not as much of a bump up around 8kHz due to the low load capacitance).

These are not night and day differences, but they're measurable and large enough in amplitude to be audible.

My pre (Project Box MM) has no settings. I plug it between TT and Amp and listen. It works fine.

Pro-Ject touts "high quality ICs" in the product pdf. I believe that means opamps for the gain stages. Input capacitance is probably either extremely low, or Pro-Ject adds a small value cap from input to ground to load the cartridge. No way of knowing what they did without either opening it up and looking, or finding an accurate schematic.
 

restorer-john

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Sorry if this comes off as overly pedantic, but I don't believe this statement is actually correct and I wanted to clear up any misconceptions.

There should be no correlation between the physical position of the volume control knob and distortion except how it affects the signal level that reaches the amplifier circuit input. Perhaps noise, but not distortion.
The way this works is this:
  1. Let's say you have an amplifier that clips with 2V input, and that it has gain of 20X (26dB). This amp will clip with a source voltage of 100mV driving it (2V/20 = 0.1V).
  2. Let's also say you find the perfect listening volume is attained with an average of 1mV driving the amplifier. That will be amplified by 20X to 20mV average, allowing another 4X of amplification (12dB of 'headroom') .
EXAMPLE A:
Let's say audio source A has an average output level of 0.1V (100mV). This source has 100X more output voltage than necessary to clip the amplifier driving the speakers. You will need to put a volume control on the input and turn it down enough to attenuate the input by 100X, or -40dB.

Let's say that puts the volume control at exactly 12 o'clock in its rotation, or 50% (half-way up).

EXAMPLE B:
Now, let's say audio source B has an average output level of 0.01V (10mV). You will need to attenuate this signal less to take it down to our sweet spot of 1mV average signal to the amplifier circuit's input. The signal will need to be attenuated by 10X (-20dB) from 10mV average down to 1mV average.

Let's say that means the volume control will now be at 3 o'clock in its rotation, or 75% (three-quarters of the way up).

In both cases, Ex. A and Ex. B, we've used the volume control to attenuate the incoming average signal level to 1mV.
It does not matter at what position the volume control is set. What matters is the signal level applied to the input of the amplifier.

If an amplifier distorts with even a tiny signal on it just because you turn its volume control up to 75%, then there is something very wrong with that amplifier.

Sorry, none of this makes any sense.

We are talking phono stages which have a fixed gain for both MM (~35dB) and MC (~60dB) and sit up front of the volume, balance, tone and line stages- before going into the power amp in vintage amps/receivers.

Also, you need to consider volume controls have a psuedo logarithmic taper law. Half-way position of a typical 270 degree pot rotation is not 50% of the resistance value- not even close.

To give you an actual idea, a typical vintage phono stage will have a rated sensitivity of 2.5mV for rated output. That 'rated' ouput with vintage gear was typically 150mV at the tape outs, which also happens to be the same rated sensitivity for a typical line level (AUX/tuner/Tape) in order to achieve rated output or, in the case of an integrated amplifier, full rated power output.

So, 2.5mV for 150mV out is that magic number again, ~35dB. Thing is, with 35dB gain you only have a limited window and that usually tops out around 120-150mV on typical vintage RIAA stages, giving a 34-35dB overload margin. A 5mV nominal cartridge will overload with 27dB of overload and higher (say 10mV) carts, even less.
 

tonycollinet

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Sorry, none of this makes any sense.

We are talking phono stages which have a fixed gain for both MM (~35dB) and MC (~60dB) and sit up front of the volume, balance, tone and line stages- before going into the power amp in vintage amps/receivers.

Also, you need to consider volume controls have a psuedo logarithmic taper law. Half-way position of a typical 270 degree pot rotation is not 50% of the resistance value- not even close.

To give you an actual idea, a typical vintage phono stage will have a rated sensitivity of 2.5mV for rated output. That 'rated' ouput with vintage gear was typically 150mV at the tape outs, which also happens to be the same rated sensitivity for a typical line level (AUX/tuner/Tape) in order to achieve rated output or, in the case of an integrated amplifier, full rated power output.

So, 2.5mV for 150mV out is that magic number again, ~35dB. Thing is, with 35dB gain you only have a limited window and that usually tops out around 120-150mV on typical vintage RIAA stages, giving a 34-35dB overload margin. A 5mV nominal cartridge will overload with 27dB of overload and higher (say 10mV) carts, even less.
I think he's just pointing out that it is not the volume knob position that determines if an amp will distort, but whether the input signal multiplied by the amp gain (after volume attenuation) is enough to drive the amp into clipping.
 

rongon

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To give you an actual idea, a typical vintage phono stage will have a rated sensitivity of 2.5mV for rated output. That 'rated' ouput with vintage gear was typically 150mV at the tape outs, which also happens to be the same rated sensitivity for a typical line level (AUX/tuner/Tape) in order to achieve rated output or, in the case of an integrated amplifier, full rated power output.

Are those peak voltages, or 'continuous' voltages?

These days, we have to reconcile the output levels from our analog sources with the 'rated' output from digital sources (CDs, DACs) which is 2V rms for 0dBFS (full scale output). Is there any way to align the digital 2V rms @ 0dBFS standard with the vintage 'rated' output levels from phono and tuner? My understanding is that the signal output level from vintage FM tuners is quite a bit lower than from CD players and DACs.

I figure if you want your analog sources to match your digital sources at any given volume level setting in your system, you want your RIAA stage to supply enough gain to reach 2V rms continuous at full modulation. I've found by trial and error that an RIAA preamp with 35dB gain always sounds noticeably lower in level than the levels from my DAC or CD player. I'm finding I prefer about 40dB of gain from the RIAA stage.

The nominal output levels from contemporary MM cartridges for hi-fi seem to fall in the 3 to 5 mV range. The Shure M44X DJ cartridge was rated for a whopping 9.5mV nominal output. I'd say stay away from DJ carts for hi-fi use.

So now the question is, at least for anyone who cares about this, what amount of gain (at 1kHz) does the RIAA stage have to provide to get the playback level from a typical hi-fi MM cartridge with 3 to 5mV nominal output make a close enough match to the level from a CD player or DAC?

And speaking of output levels...

Tube advantages: Some people enjoy fussing with tubes, that's all.

Actually, there is one advantage to using tubes for an RIAA preamp. Voltage swing. Since tubes operate at high supply voltages they can swing lots of volts. (They cannot swing lots of current into a low impedance load, but add a good high voltage MOSFET for an output buffer and that problem can be solved.) That means a tube RIAA preamp can have loads and loads of headroom -- far more than from any opamp -- as long as you don't implement the RIAA equalization in the tubes' feedback loop (i.e., use passive equalization in between tube voltage gain stages). OK, that's kind of complicated. But it is an advantage tubes have over most transistors, and certainly over opamps.
 
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tonycollinet

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So now the question is, at least for anyone who cares about this, what amount of gain (at 1kHz) does the RIAA stage have to provide to get the playback level from a typical hi-fi MM cartridge with 3 to 5mV nominal output make a close enough match to the level from a CD player or DAC?
5mV to 2V is x400 = (near as damnit) 52dB

3mV to 2V is about 56.5dB
 
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rongon

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5mV to 2V is x400 = (near as damnit) 52dB

Yes, it's been a problem for me.
I recently built a Elliot Sound Products Project-06 preamp, but changed the values of the resistor in one of the opamp's negative feedback loops to goose the preamp's total gain up to about 44dB gain at 1kHz. That seemed to do it.

I have a friend who doesn't listen to anything digital. He's much more of a purist than I am. He finds my RIAA preamp has too high gain for his setup. I think his power amp has more gain than the amps in my LSR305 speakers (which I run wide open).

I was sincere when I asked how to reconcile the old output level ratings for AUX, tuner, phono inputs with the digital standard of 2V rms @ 0dBFS.
The specs from a Sony CD player I had said 200mV rms rated output for -10dBv, which kind of makes my head spin.

At any rate, I think applying 50dB of gain (at 1kHz) to a MM cart with 5mV rms nominal output presents too many problems with headroom, or overloading on every bad tick or pop -- unless you use a high output moving coil cart with about half (-6dB) the output of a typical MM cart.

Analog nominal signal levels are all over the place. Digital is so orderly...
 

tonycollinet

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Yes, it's been a problem for me.
I recently built a Elliot Sound Products Project-06 preamp, but changed the values of the resistor in one of the opamp's negative feedback loops to goose the preamp's total gain up to about 44dB gain at 1kHz. That seemed to do it.

I have a friend who doesn't listen to anything digital. He's much more of a purist than I am. He finds my RIAA preamp has too high gain for his setup. I think his power amp has more gain than the amps in my LSR305 speakers (which I run wide open).

I was sincere when I asked how to reconcile the old output level ratings for AUX, tuner, phono inputs with the digital standard of 2V rms @ 0dBFS.
The specs from a Sony CD player I had said 200mV rms rated output for -10dBv, which kind of makes my head spin.

At any rate, I think applying 50dB of gain (at 1kHz) to a MM cart with 5mV rms nominal output presents too many problems with headroom, or overloading on every bad tick or pop -- unless you use a high output moving coil cart with about half (-6dB) the output of a typical MM cart.

Analog nominal signal levels are all over the place. Digital is so orderly...
Digital is all over the place also. 2V is far from a standard. Then every amp seems to have a different gain/sensitivity.
 

restorer-john

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So now the question is, at least for anyone who cares about this, what amount of gain (at 1kHz) does the RIAA stage have to provide to get the playback level from a typical hi-fi MM cartridge with 3 to 5mV nominal output make a close enough match to the level from a CD player or DAC?

Stay tuned...

12 vintage preamplifiers/amplifiers tested over the last few weekends for phono stage overloads and outputs.

I'll link to the thread when I post it.
 

JeffS7444

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In the old days, Stanton, Pickering, Shure cartridges used this LCR resonance to compensate for the falling frequency response of most MM cartridge assemblages, so they would recommend much higher load capacitances like 450pF. Audio Technica et al no longer do this. They design their cartridges to work into a 150pF (or thereabouts) load, or 3X lower. That's a pretty big difference.
I've sometimes wondered why more "perfectionist" turntables don't offer on-board preamplifier as an option, because that's easiest way to achieve the lowest possible cable capacitance
 

rongon

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Stay tuned...

12 vintage preamplifiers/amplifiers tested over the last few weekends for phono stage overloads and outputs.

I'll link to the thread when I post it.
Will any of them have tube RIAA stages?
If yes, would those all be of the vintage style with the RIAA EQ implemented in the NFB loop? Or would any use tubes and a passive RIAA EQ network?
 

Chrispy

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Will any of them have tube RIAA stages?
If yes, would those all be of the vintage style with the RIAA EQ implemented in the NFB loop? Or would any use tubes and a passive RIAA EQ network?
Tube RIAA? How the hell does that work?
 

rongon

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???

Do you mean, "That always sucks, so why would anyone do that??"?
 

restorer-john

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Tube RIAA? How the hell does that work?

The relevant part of the schematic in an ARC SP-8 (left channel shown).

1666067505004.png


Not shown, 390V hybrid SS/tube regulated power supply and heater supplies
 

Timcognito

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So if the source is same and the loudest you want to play is 50% of volume knob with that fixed source, the amp will distort or clip just as much as at 90% volume knob?

FYI I'm an ME, not an EE, and sorry if my rule of thumb is bunk.
 
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