Maximum output from a MM cartridge.
For the Vinyl experts.
The 'typical' MM cartridge is specified at about 5mV output for a velocity of 5cm/sec . I think I read somewhere that the maximum output of the cartridge could be about 350mV on musical peaks.
The question is ,what is the maximum signal level over the full bandwidth ( 20 ~ 20KHz) that a MM cartridge can produce with a sensitivity of 1mV per cm/sec at 1KHz. I am assuming that this is measured using a vinyl disc with the highest recorded levels . Maybe the 1812 Overture?
Cheers.
For the Vinyl experts.
The 'typical' MM cartridge is specified at about 5mV output for a velocity of 5cm/sec . I think I read somewhere that the maximum output of the cartridge could be about 350mV on musical peaks.
The question is ,what is the maximum signal level over the full bandwidth ( 20 ~ 20KHz) that a MM cartridge can produce with a sensitivity of 1mV per cm/sec at 1KHz. I am assuming that this is measured using a vinyl disc with the highest recorded levels . Maybe the 1812 Overture?
Cheers.
Just found the answer.
I found some white papers at the Vandenhul site which has the answer - or does it ?
http://www.vandenhul.com/artpap/phono_faq.htm#78
It says the absolute max output expected is about 71mV for a cartridge with a sensitivity of 1mV / 5.7cm/sec. So for a sensitivity of 5mV it must be around 350mV !
So a linear front end ( buffer ) amp should be able to handle that signal without clipping. Assuming an opamp with +/- 15 volt rails, you should be able to get at least 7Volts rms unclipped. So the gain can be at least 7/0.35 = 20 or about 26db.
Correct ?
Cheers.
I found some white papers at the Vandenhul site which has the answer - or does it ?
http://www.vandenhul.com/artpap/phono_faq.htm#78
It says the absolute max output expected is about 71mV for a cartridge with a sensitivity of 1mV / 5.7cm/sec. So for a sensitivity of 5mV it must be around 350mV !
So a linear front end ( buffer ) amp should be able to handle that signal without clipping. Assuming an opamp with +/- 15 volt rails, you should be able to get at least 7Volts rms unclipped. So the gain can be at least 7/0.35 = 20 or about 26db.
Correct ?
Cheers.
Not really. The split passive EQ was my most successfull foray into opamp phonos, it had obvious dynamic shortcomings but extraordinarily good PRAT.
What i played with for a while was a variation of the El Cheapo with an added BUF634 within the FB loop. OPA627/637 are obviously not my cup of tea but AD8610 sounded reasonably good and allowed for very low dc offset. PS was discrete, series, open loop regulated. The sound? Good bass and reasonable, but not great PRAT. So-so dynamics, **** poor voices and very low soundstage. Musically i would rate it inferior to the phono section of a NAD3020A (5 transistors IIRC).
Using the same RIAA values and PS but replacing the opamp with a discrete (Aleph OnO) brings real improvements as far as dynamics and human voices are concerned but bass and PRAT are just ok.
Interestingly i like the sound of the Ono better with reduced PS to 20v. A 500VA transformer makes a huge difference up from a 60VA. Bang goes my intention to build a cute small SS phono
I guess it's back to tubes.
MC via an opamp? Wouldn't dream of it
Konnichiwa,
I hate to tell you, but it seems your design was a poor one, not my one. Do yourself a favour and build the Phonostage EXACTLY as I suggest, battery supply, exact decoupling of PSU lines, OPA637 et al, plus add the output Biasing. No added buffers, bugged up regulated supplies etc.
Sayonara
analog_sa said:
I hate to tell you, but it seems your design was a poor one, not my one. Do yourself a favour and build the Phonostage EXACTLY as I suggest, battery supply, exact decoupling of PSU lines, OPA637 et al, plus add the output Biasing. No added buffers, bugged up regulated supplies etc.
Sayonara
I hate to tell you but i started with exactly your design . The addition of the BUF634 was slightly beneficial. Of course it works better with batteries than 'bugged up regulated supplies'.
This is pretty much irrelevant as the discrete opamp uses the same power source. You don't seriously suggest that a simple discrete opamp is more sensitive to PS than a 637?
I guess it all boils down to sound priorities and preferences. Ours seem to be a world apart. And maybe i have elevated opamp intolerance
I really try hard to like them but they all (and i've tried lots) have the same sonic signature. Twenty something years on and they all sound like a 5534 where it counts.
What.......... ?
"I suppose I am not the only one having a good laugh at the name of the engineer and drawer of that schematic. "
I'll tell Beau you find his name funny at lunch next week. You are lucky you are in Sweden. Mr. Platz is about 6'5" and played college football for the Arkansas Razorbacks.........
"I suppose I am not the only one having a good laugh at the name of the engineer and drawer of that schematic. "
I'll tell Beau you find his name funny at lunch next week. You are lucky you are in Sweden. Mr. Platz is about 6'5" and played college football for the Arkansas Razorbacks.........
Konnichiwa,
On a scale of 10 I'd give ElCheapor an 8.5, my current Phono is on 9.75 for comparison. As I have the choice, yes, I listen to something else. But that "else" has a 1:15 differnetial in cost and much in complexity and is not that much better than ElCheapo.
So I guess it does come down to taste and perception, PLUS system context.
Sayonara
analog_sa said:On second thought this is probably wrong. You like the El Cheapo but wouldn't actually listen to it given a choice, would you?
On a scale of 10 I'd give ElCheapor an 8.5, my current Phono is on 9.75 for comparison. As I have the choice, yes, I listen to something else. But that "else" has a 1:15 differnetial in cost and much in complexity and is not that much better than ElCheapo.
So I guess it does come down to taste and perception, PLUS system context.
Sayonara
Re: Re: Ultrasimple mm/mc riaa preamp
Goedemorgen Kuei Yang Wang,
I received the following email from Pat's Lab which I reproduce here with full permission:
Thank you for visiting our site, and your kind words.
Yes, it appears that there is an error in the drawing that you refer to.
Please accept our apologies for this. Perhaps we need to add a "checked by"
line in the title block. When built as it is intended, we can assure you
that the RIAA response is accurate. We did not make provisions for the
additional IEC and Neumann time constants, as this is intended to be a
"simple" MM preamp.
In response to the other issues that you raise, we feel that it is very
discouraging that someone would see fit to make derogatory remarks about it
without building, testing, or listening to one. We have strong feelings that
passive EQ allows for accurate deemphasis that is not possible with a
feedback network.This is due to pole-zero interaction, and the effect of
finite open-loop gain. If you will examine the open-loop gain of the op-amp
that we chose, you may better understand why we feel that is it a good
choice to be used with passive networks.
As for suitability with MC cartridges, it is possible that the 100 ohm
resistor could be lowered to achieve additional gain. However, we have not
tested it in this manner. The cartridges that we use have an output in the
range of 3-4 mV. We prefer using inexpensive cartridges, and using the money
that we save to buy more records.
We thank you for your invitation to visit and register on your favorite
forum. We would prefer to remain independent. If you like, you may post this
e-mail in its entirety on your forum, if its rules permit. You have our
permission to do so.
Regards,
"P., B., and J." @ Pat's Lab
I addition to that I can submit that the circuit is very similar to the one in Analog Devices Application Note 124 fig.3.
Tot ziens.
Kuei Yang Wang said:
Goedemorgen Kuei Yang Wang,
I received the following email from Pat's Lab which I reproduce here with full permission:
Thank you for visiting our site, and your kind words.
Yes, it appears that there is an error in the drawing that you refer to.
Please accept our apologies for this. Perhaps we need to add a "checked by"
line in the title block. When built as it is intended, we can assure you
that the RIAA response is accurate. We did not make provisions for the
additional IEC and Neumann time constants, as this is intended to be a
"simple" MM preamp.
In response to the other issues that you raise, we feel that it is very
discouraging that someone would see fit to make derogatory remarks about it
without building, testing, or listening to one. We have strong feelings that
passive EQ allows for accurate deemphasis that is not possible with a
feedback network.This is due to pole-zero interaction, and the effect of
finite open-loop gain. If you will examine the open-loop gain of the op-amp
that we chose, you may better understand why we feel that is it a good
choice to be used with passive networks.
As for suitability with MC cartridges, it is possible that the 100 ohm
resistor could be lowered to achieve additional gain. However, we have not
tested it in this manner. The cartridges that we use have an output in the
range of 3-4 mV. We prefer using inexpensive cartridges, and using the money
that we save to buy more records.
We thank you for your invitation to visit and register on your favorite
forum. We would prefer to remain independent. If you like, you may post this
e-mail in its entirety on your forum, if its rules permit. You have our
permission to do so.
Regards,
"P., B., and J." @ Pat's Lab
I addition to that I can submit that the circuit is very similar to the one in Analog Devices Application Note 124 fig.3.
Tot ziens.
Re: Re: Re: Ultrasimple mm/mc riaa preamp
Konnichiwa,
But not when build as drawn originally.
Looking at the names and the circuit as drawn I was forced to draw the conclusion the schematic was a ludibrium.
The revised design is indeed flat in RIAA response, assuming narrow Tolerance capacitors.
These timeconstants do not make the circuit any more excessivley complex than it already is, anyway.
I have build very similar circuits before and my remarks hold in the areas criticised.
The first stage has a gain of 1+10k1/K1 or 102. With a "standard" 5mV rated cartride with peak outputs in the 350mV range this will pretty reliably clip the input stage with high level signals, especially with the kind of dirac pulses found with loud clicks but potentially also when the record is cut with high levels, examples may include many Audiophile pressings and many DJ 12". The overall gain
Secondly, the use of a passive EQ further reduces the overload margin at high frequencies by about 40db, in a design that already has a poor overload margin due to it's gainstructure.
The implications on the S/N ratio are material too. And if more normal Op-Amp's (lower bandwidth) had been used there would also be implications at higher frequencies. Of course, the price paid for using fast Op-Amp's is excessive noise, which is specified at 12nV|/Hz leading to an Ein of 1.7uF or a S/N ratio of -70db linear with respect to a 5mV input and -56db referred to a 1mV input.
I have found quite reliably that +/-15V supplied op-amp's lack the dynamic range required for use with passive EQ's. IN PRINCIPLE I am in favour of passive equalisation, but not if it leads to drastic tradeoffs elsewhere.
And if we observe noise and output range it is a rather poor choice, from the available ones.
Well, using a (not untyphical) 0.2mV pickup the input reffered S/N ratio will plummet to around 41db. I find -56db Input referred S/N ratio easily audible in the pauses between music (and thus by definition low level detail is also effected) but -41db is absolutely unacceptable. So MC's are out unless the first Op-Amp is changed to something a lot quieter, like an AD797.
One of the best inexpensive cartridges is the Denon DL-103, which happens to be a low output MC.
Very good. This adresses non of the critique points raised.
I PERSONALLY would for MM simply return to the much simpler 1 Op-Amp feedback combo with suitable Op-Amp's (yes, even the AD825 would be nice here) if simplicity with good sound is the goal, this way noise is better controlled by far and the overload margin is not frequency dependent.
Sayonara
Konnichiwa,
Elso Kwak said:
But not when build as drawn originally.
Looking at the names and the circuit as drawn I was forced to draw the conclusion the schematic was a ludibrium.
The revised design is indeed flat in RIAA response, assuming narrow Tolerance capacitors.
Elso Kwak said:
These timeconstants do not make the circuit any more excessivley complex than it already is, anyway.
Elso Kwak said:
I have build very similar circuits before and my remarks hold in the areas criticised.
The first stage has a gain of 1+10k1/K1 or 102. With a "standard" 5mV rated cartride with peak outputs in the 350mV range this will pretty reliably clip the input stage with high level signals, especially with the kind of dirac pulses found with loud clicks but potentially also when the record is cut with high levels, examples may include many Audiophile pressings and many DJ 12". The overall gain
Secondly, the use of a passive EQ further reduces the overload margin at high frequencies by about 40db, in a design that already has a poor overload margin due to it's gainstructure.
The implications on the S/N ratio are material too. And if more normal Op-Amp's (lower bandwidth) had been used there would also be implications at higher frequencies. Of course, the price paid for using fast Op-Amp's is excessive noise, which is specified at 12nV|/Hz leading to an Ein of 1.7uF or a S/N ratio of -70db linear with respect to a 5mV input and -56db referred to a 1mV input.
Elso Kwak said:
I have found quite reliably that +/-15V supplied op-amp's lack the dynamic range required for use with passive EQ's. IN PRINCIPLE I am in favour of passive equalisation, but not if it leads to drastic tradeoffs elsewhere.
Elso Kwak said:
And if we observe noise and output range it is a rather poor choice, from the available ones.
Elso Kwak said:
Well, using a (not untyphical) 0.2mV pickup the input reffered S/N ratio will plummet to around 41db. I find -56db Input referred S/N ratio easily audible in the pauses between music (and thus by definition low level detail is also effected) but -41db is absolutely unacceptable. So MC's are out unless the first Op-Amp is changed to something a lot quieter, like an AD797.
Elso Kwak said:
One of the best inexpensive cartridges is the Denon DL-103, which happens to be a low output MC.
Elso Kwak said:
Very good. This adresses non of the critique points raised.
I PERSONALLY would for MM simply return to the much simpler 1 Op-Amp feedback combo with suitable Op-Amp's (yes, even the AD825 would be nice here) if simplicity with good sound is the goal, this way noise is better controlled by far and the overload margin is not frequency dependent.
Sayonara
A note on the maximum signal available.
The maximum signal output expected from a vinyl groove is about 350mV . This is due to the stylus velocity.
The Shure V15 specifies a maximum trackability of 80cm/sec at 5Khz and 60cm/sec at 10Khz.
The cartridge output depends on the groove velocity which varies with frequency. By that I mean a 1Khz signal and a 10Khz signal of same amplitude will have different groove velocity , the 10Khz having much higher velocity.
So when we talk of a maximum of say 70cm/sec we need not be talking about 1Khz or 10Khz - just groove velocity.
What I am getting at is that the preamp input will not see a voltage higher than say 350mV no matter what the frequency is. With a gain of about 20 it will comfortably handle any input peaks.
So HF overload is not a separate issue from this. Everything is taken care of. There should be no problems with HF . One could always include a Hf roll off beyond 20Khz in the first stage to take care of any severe clicks and pops. In any case a record that noisy will be a nuisance to listen to .
The cartridge plus loading in any case have a HF roll off beyond say 30Khz. So supersonic frequencies may not have any significant amplitude at all.
Cheers.
The maximum signal output expected from a vinyl groove is about 350mV . This is due to the stylus velocity.
The Shure V15 specifies a maximum trackability of 80cm/sec at 5Khz and 60cm/sec at 10Khz.
The cartridge output depends on the groove velocity which varies with frequency. By that I mean a 1Khz signal and a 10Khz signal of same amplitude will have different groove velocity , the 10Khz having much higher velocity.
So when we talk of a maximum of say 70cm/sec we need not be talking about 1Khz or 10Khz - just groove velocity.
What I am getting at is that the preamp input will not see a voltage higher than say 350mV no matter what the frequency is. With a gain of about 20 it will comfortably handle any input peaks.
So HF overload is not a separate issue from this. Everything is taken care of. There should be no problems with HF . One could always include a Hf roll off beyond 20Khz in the first stage to take care of any severe clicks and pops. In any case a record that noisy will be a nuisance to listen to .
The cartridge plus loading in any case have a HF roll off beyond say 30Khz. So supersonic frequencies may not have any significant amplitude at all.
Cheers.
Passive RIAA Fact or Fiction
Kuei Yang Wang
I have never seen a cartridge that can even come close to putting out 350mv, even at the highest frequency, however I don’t use Radio Shack cartridges and don't care about the ability to reproduce pops or clicks. However If your concerned about overload margin with some of the high out put cartridges the gain of the input opamp can be reduced to 30db with out penalty to the passive network.
As for as noise performance goes it best to have the majority if not all the gain in the first amp. Speaking of the circuit noise, if the gain was split 20db and 20db between the amps the noise then becomes greater than having the majority of the gain in the first amp. This is normally called adding the sum of the squares. Noise adds not multiplies through the changing of amps, do the math.
The passive network also allows the use to select the lowest values of components As apposed to the active feedback RIAA amp where the values do increase the current noise.
So the lower the impedance of the passive network lowers the circuit’s noise compared to the active circuit.
Also since the first amp runs at high gain it does not need to be unity gain stable and compensation is not needed. So the user has more options in the selection of amps. The active RIAA will increase the number of poles and change the open loop characteristics of the amplifier causing distortion and instability. So, the response of the passive circuit has better performance at high frequencies because it has much less interaction between the feedback network.
So picking this topology as a problem is barking up the wrong tree. However maybe we have, we shown you that this circuit has more potential than you realized, and you’ll try again with it or maybe you just want to argue.
Also, there are a number of way to design an implementation the passive RIAA beside the way it was done in PatsLab. Also, the fact is that all of the passive RIAA network don't have the same formulas. I can list a few if your really interested.
Kuei Yang Wang
I have never seen a cartridge that can even come close to putting out 350mv, even at the highest frequency, however I don’t use Radio Shack cartridges and don't care about the ability to reproduce pops or clicks. However If your concerned about overload margin with some of the high out put cartridges the gain of the input opamp can be reduced to 30db with out penalty to the passive network.
As for as noise performance goes it best to have the majority if not all the gain in the first amp. Speaking of the circuit noise, if the gain was split 20db and 20db between the amps the noise then becomes greater than having the majority of the gain in the first amp. This is normally called adding the sum of the squares. Noise adds not multiplies through the changing of amps, do the math.
The passive network also allows the use to select the lowest values of components As apposed to the active feedback RIAA amp where the values do increase the current noise.
So the lower the impedance of the passive network lowers the circuit’s noise compared to the active circuit.
Also since the first amp runs at high gain it does not need to be unity gain stable and compensation is not needed. So the user has more options in the selection of amps. The active RIAA will increase the number of poles and change the open loop characteristics of the amplifier causing distortion and instability. So, the response of the passive circuit has better performance at high frequencies because it has much less interaction between the feedback network.
So picking this topology as a problem is barking up the wrong tree. However maybe we have, we shown you that this circuit has more potential than you realized, and you’ll try again with it or maybe you just want to argue.
Also, there are a number of way to design an implementation the passive RIAA beside the way it was done in PatsLab. Also, the fact is that all of the passive RIAA network don't have the same formulas. I can list a few if your really interested.
350 mV from a MM cartridge!!!!!!
You are as confused as a barking bird. I would like to see a cartridge that can output that much.
It would overlaod any amplifier, too. How do you explain that, bub?
You can't.
The maximum voltage that a cartridge like the one these guys probably like (I am guessing a $20 Grado, maybe a $40 one when they feel lucky) will be roughly 20 mV. So.......2 volts max in the first stage.......and then attenuated in the passive EQ.
Yeah........35 volts output from a preamp. Give us all a break, pal.
Jocko
You are as confused as a barking bird. I would like to see a cartridge that can output that much.
It would overlaod any amplifier, too. How do you explain that, bub?
You can't.
The maximum voltage that a cartridge like the one these guys probably like (I am guessing a $20 Grado, maybe a $40 one when they feel lucky) will be roughly 20 mV. So.......2 volts max in the first stage.......and then attenuated in the passive EQ.
Yeah........35 volts output from a preamp. Give us all a break, pal.
Jocko
Re: 350 mV from a MM cartridge!!!!!!
Konnichiwa,
I have a Cartridge rated 6.5mV/5cm/s and it tracks reliably a +16db track on a testrecord, outputting thusly around 40mV lineary. Higher levels can be tracked by this pickup, as evidenced by some 12" DJ Pressings.
I have somewhere a complete set of calculations, based on stylus velocity etc. which suggest a the ability of the LP to have surprisingly high levels (and we are not talking telarc 1812 either). The 350mV came from a teoretical calaculation of trackable velocity earlier in the thread. I would expect on LP's cut to the limit still > 100mV with higher output MM Pickups on peaks, from experience.
And again, if your pop or click from some dust overloads or slews the Op-Amp (slewing not in your design) then the noise becomes more audible then it would be when it is not clipped.
I'm not sure about $ 40 Grados, never used one. But decent cartridges can track quite some level and it is present on more than a few LP's.
No matter how you turn and twist it, with passive EQ you are trading noise and overload margin and you don't have that much of either if you use Op-Amp's (you have tons of overload margin and very low noise using outdated and obsolete Valves, but that is another story). At best the tradeoff barely works well, at worst it either hisses a lot or clicks and clips a lot.
Sayonara
Konnichiwa,
Jocko Homo said:
I have a Cartridge rated 6.5mV/5cm/s and it tracks reliably a +16db track on a testrecord, outputting thusly around 40mV lineary. Higher levels can be tracked by this pickup, as evidenced by some 12" DJ Pressings.
I have somewhere a complete set of calculations, based on stylus velocity etc. which suggest a the ability of the LP to have surprisingly high levels (and we are not talking telarc 1812 either). The 350mV came from a teoretical calaculation of trackable velocity earlier in the thread. I would expect on LP's cut to the limit still > 100mV with higher output MM Pickups on peaks, from experience.
And again, if your pop or click from some dust overloads or slews the Op-Amp (slewing not in your design) then the noise becomes more audible then it would be when it is not clipped.
I'm not sure about $ 40 Grados, never used one. But decent cartridges can track quite some level and it is present on more than a few LP's.
No matter how you turn and twist it, with passive EQ you are trading noise and overload margin and you don't have that much of either if you use Op-Amp's (you have tons of overload margin and very low noise using outdated and obsolete Valves, but that is another story). At best the tradeoff barely works well, at worst it either hisses a lot or clicks and clips a lot.
Sayonara
Shelved Bass
The average bass response in my Pearl is something I would like to fix. This is the one area that could use improvement.
There is a 23 ufd cap on the coupling the output. The 2SK389 transistors were selected for a high current draw. Each channel is running 13 -14 ma now.
The input is feed with a pair of 2SK170BL jfets and cascoded with a ZTX450. The coupling cap here measures 1.03 ufd and the imput of the Pearl measures 45.4K.
Compared to my tube phono and stepups the bass is much tighter and clear. Very reduced in level though. I could blame this on the doubling and mushy tube phono bass just seeming larger.
But my disc player delivers chest and room pressurizing low end response that you feel and cannot really hear. The phono cannot duplicate this type of bottom end. The arm is an OLRB-250 and cartridge is a Denon 103R.
Is the RIAA circuitry the culprit, or is there another weakness in there somewhere?
George
analog_sa said:
Using the same RIAA values and PS but replacing the opamp with a discrete (Aleph OnO) brings real improvements as far as dynamics and human voices are concerned but bass and PRAT are just ok.
Interestingly i like the sound of the Ono better with reduced PS to 20v. A 500VA transformer makes a huge difference up from a 60VA. Bang goes my intention to build a cute small SS phono
I guess it's back to tubes.
MC via an opamp? Wouldn't dream of it
The average bass response in my Pearl is something I would like to fix. This is the one area that could use improvement.
There is a 23 ufd cap on the coupling the output. The 2SK389 transistors were selected for a high current draw. Each channel is running 13 -14 ma now.
The input is feed with a pair of 2SK170BL jfets and cascoded with a ZTX450. The coupling cap here measures 1.03 ufd and the imput of the Pearl measures 45.4K.
Compared to my tube phono and stepups the bass is much tighter and clear. Very reduced in level though. I could blame this on the doubling and mushy tube phono bass just seeming larger.
But my disc player delivers chest and room pressurizing low end response that you feel and cannot really hear. The phono cannot duplicate this type of bottom end. The arm is an OLRB-250 and cartridge is a Denon 103R.
Is the RIAA circuitry the culprit, or is there another weakness in there somewhere?
George
Maximum cartridge output.
For those who missed part of the thread.
The 350 mV figure came from Vandenhul , the cartridge people !
(check the link )
In addition I remember reading this in Wireless World many years ago when Vinyl was king.
I think this translates to over 120cm/sec groove velocity. Pick your cartridge and determine its maximum output. With lower sensitivities the " 350mV " figure will be much lower.
This was a Maximum Limit EVER possible and is much higher than the maximum groove velocity seen in commercial pressings. The figure was arrived at to design phono stages that would never overload under any circumstance. It is possible that an ocassional pop , even minor ones , could slew much faster than 70cm/sec. A piece of dust in the groove will produce a much faster stylus deflection than any recorded signal. So one has to take this into account . This is why probably many tube RIAA stages can sound "quieter" than some ss RIAA stages.
Cheers.
For those who missed part of the thread.
The 350 mV figure came from Vandenhul , the cartridge people !
(check the link )
In addition I remember reading this in Wireless World many years ago when Vinyl was king.
I think this translates to over 120cm/sec groove velocity. Pick your cartridge and determine its maximum output. With lower sensitivities the " 350mV " figure will be much lower.
This was a Maximum Limit EVER possible and is much higher than the maximum groove velocity seen in commercial pressings. The figure was arrived at to design phono stages that would never overload under any circumstance. It is possible that an ocassional pop , even minor ones , could slew much faster than 70cm/sec. A piece of dust in the groove will produce a much faster stylus deflection than any recorded signal. So one has to take this into account . This is why probably many tube RIAA stages can sound "quieter" than some ss RIAA stages.
Cheers.
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