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P-Mounts: Do you like them?

Not so, p-mount or more correctly T4P, is every bit as good as 1/2" or the various alternate mounting systems that have appeared on proprietary tables over the years.

It was launched by Technics with distinctly high end arms (eg: EPA102mkII)

The standards are (courtesy of Flavio's posting on VE)

So here are the standards:

- VTF 1.25g +- 0.25g with a cartridge+stylus weight of 6.00g

- As far as i know, compliance is within 10-12 units @100Hz, which would be like 25cu static compliance.

- Stylus-tip-to-mating-surface is exactly 20mm. This is critical otherwise the cartridge will not be aligned and tracking error will appear.

- Center of gravity is standarized, but i don't know the details.

- Plug length 5mm, height 8mm
- Plug pins length 4.2mm, diameter 0.7mm
- Hole for fastening screw is 2.2mm diameter
- Hole-to-mating-surface distance 3mm
- Stylus is expected to be 8.5mm below the center of the hole for the fastening screw.
- Stylus to cartridge floor distance 1mm (at least for technics carts)
- Cart height 16mm approx (it will vary from manufacturer to manufacturer)
Click to expand...

The higher end cartridges from Technics and most other manufacturers appear to have complied with the standards - making alignment easy! (plug and play high end!)

What SA-708's measurements make clear is that there are a number of purportedly T4P cartridges/styli out there that in fact are non compliant.

I have also had issues with Shure p-mount cartridges (with and without SAS) - although I have not gone as far as verifying the mountings with a caliper - but my observation has been that they tend to be around 1mm out.

This of course impacts on alignment, tracking and distortion...

Although, I don't believe it to be as critical with a linear tracking arm as with a pivoted arm.

Someone would need to do the math on the incremental distortion introduced by having the stylus location 1mm forward of the aligned location....

There is nothing inherently "low rent" about T4P - like anything it is all in the execution!

An it is clear that lower end p-mount (note I do not call these T4P as they are non-compliant) setups and components were less than ideal - is anyone surprised ?! - and even then it is merely an indication of careless engineering - Technics sold the SL-B100 for the princely sum of $90 - and it was fully compliant with T4P. (but were the low end cartridges also compliant? apparently not!)
 
dlaloum said:
Not so, p-mount or more correctly T4P, is every bit as good as 1/2" or the various alternate mounting systems that have appeared on proprietary tables over the years.

What SA-708's measurements make clear is that there are a number of purportedly T4P cartridges/styli out there that in fact are non compliant.


This of course impacts on alignment, tracking and distortion...


Although, I don't believe it to be as critical with a linear tracking arm as with a pivoted arm.

Someone would need to do the math on the incremental distortion introduced by having the stylus location 1mm forward of the aligned location....
Click to expand...

I'm not saying a P mount cartridge isn't worthy of playing a record at all.
Some are better than others, just like the 1/2 inchers.
You get what you pay for -to a point - that is a long-time rule of things.
Think diminishing returns.
But to even quabble about a millimeter difference in a swinging tonearm that's ONLY perfectly aligned in the grooves at perhaps TWO points over a record is utter insanity, or obsession.
I'd hate to observe some nutcase sitting there in holy terror while listening to his Chopin records, waiting with gritted teeth for those two sweet spots to play, so he could relax in distortion-free comfort.

Jeez, give me a break!
 
One millimeter makes a difference in cartridge alignment. I'm sure this is more important to those of us that continue to use the nicer p-mount turntables than it is to others. Swinging tone arm? You presume too much.

I have found a p-mount cartridge that measures up short, the Sony XL-MC104P, a HOMC design with a removable stylus. I'm coming up with 19mm on the two examples I have. This was not a cheap, low-end cartridge.
 
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specialone53 said:
But to even quabble about a millimeter difference in a swinging tonearm that's ONLY perfectly aligned in the grooves at perhaps TWO points over a record is utter insanity, or obsession.
I'd hate to observe some nutcase sitting there in holy terror while listening to his Chopin records, waiting with gritted teeth for those two sweet spots to play, so he could relax in distortion-free comfort.

Jeez, give me a break!
Click to expand...

You might think about being a little less insulting to those of us who care about optimizing our systems.

John
 
boreas said:
You might think about being a little less insulting to those of us who care about optimizing our systems.

John
Click to expand...

There is Optimization, and then there is extreme obsession.
Two different things.

But sorry, I'm not gonna nut my brain over this trivial issue that creates endless threads, and delves into millimeter perspctives.
At best, I find it a tad amusing.
 
specialone53 said:
There is Optimization, and then there is there';s extreme obsession.
Two different things.
Click to expand...

There's consideration for the feelings of others and then there's gratuitous rudeness. Two different things.

But sorry, I'm not gonna nut my brain over this trivial issue that creates endless threads, and delves into millimeter perspctives.
At best, I find it a tad amusing.
Click to expand...

No, no, no! Wouldn't want you to tax your brain but I suppose someone who fancies himself to be a "specialone" can't really be expected to concern himself with trivial issues like regard for other people's feelings.

John
 
boreas said:
There's consideration for the feelings of others and then there's gratuitous rudeness. Two different things.



No, no, no! Wouldn't want you to tax your brain but I suppose someone who fancies himself to be a "specialone" can't really be expected to concern himself with trivial issues like regard for other people's feelings.

John
Click to expand...

Ahh, nice try though.
Judgemental because of a screen-name.
And about the "feelings"....
I'm sorry I shook people up over something they treasure dearly..
Like a silly millimeter off in some god-forsaken territory they think is a Holy Ground of some sort.
Unless, of course, they're some sort of other-world alien being, with nano-sensitive hearing capabilities.
It utterly behooves me the whole issue.... 'cause I'm not that tightly wrapped in such nonsense.
Next, might actually be a thread concerning the thickness of Gold Plating on speaker terminals, and how that sonically influences the overall conductivity factor.
Or how tight they have to be for proper distribution of signal.

I'm on the ground, don't know about others.:smoke:
 
Without wanting to in-flame....

My question was quite relevant...

How much difference does 1mm in needle location make?

The answer is likely to be different for different length arms, and different again for linear trackers I would think - and it is a question of geometry and the harmonic distortion generated by tracking error.

If we found that the 1mm difference would increase THD by say 5% - then it would be something worth obsessing about and quite a potentially audible improvement.

If on the other hand we find that the difference is of the order of 0.05% THD, then it would be so completely swamped by other issues in the overall picture of the TT and system that it is absolutely not worth worrying about.

Without knowing which of the two it is (or where it lies in between the two extremes) - having a flaming war over it is a little pointless. (although emotive language is unhelpful)

Using the VE calculator (very handy: http://www.vinylengine.com/overhang...=15.14&oa=22&ty=h&n_oh=16.14&submit=calculate )

And entering the parameters of the SME 3009 series I, we find that increasing the overhang from 15.14mm to 16.14mm.... has the following effects:

Average RMS THD decreases by 0.009% (lets round it to 0.01%) - of little or no relevance.

Peak THD increases by 0.144% ... hmm it might have a marginal/subtle impact and it would be better not to add the 1mm - but it does not appear to be a major issue

Using the parmeters of the SME 3012 v1 - as an example of a longer arm:

Average THD increases 0.054% not a big deal...
Peak THD increases 0.139% pretty similar to the 9" arm


The calculator is of no use with a linear tracking arm...

So there you go is there an impact - YES
Is it worth worrying about at the lower end and midrange levels of performance - not really
Is it worth worrying about in terms of aiming for high end performance - yes it is. every little bit counts... and 0.14% THD is not a small amount of THD, most people would not purchase an amp that specced as 0.14% THD... we expect the order of magnitude of THD to be in the order of 0.01% to 0.05% typically.... (and we strive for much better)

Where you as an individual sit on this matter in terms of how important / critical it is to you depends on your audio aspirations....

I often like to compare to my uncle who listens to an old transistor radio, and asks why the hell anyone would bother spending the time and money getting something that doesn't even sound any different. (he adamantly insists there is no difference in sound quality between his transistor and any "stereo" he has heard) - clearly for him the 1mm difference in stylus position would be of no relevance.

For me - well I will check the stylus position more carefully on my p-mounts from now on.

bye for now

David
 
Just how significant is a silly millimeter?

There are 25.4mm in an inch. Do the math and you discover that a millimeter is 0.0394 inches. In words, a millimeter is three-hundred-and-ninety-four ten-thousandth of an inch.

The side to side contact distance of 33.3 rpm and 45 rpm styli is 0.7 mil, which in words is seven ten-thousandth of an inch. Do the math and you discover that an insignificant silly millimeter is 56.3 times longer than the side to side contact distance of your average stylus. And when you consider that the radius of a stylus' contact area is possibly two ten-thousandth of an inch for elliptical styli and even less for line contact styli, in the environment of the record groove a millimeter becomes something to be concerned with.

And I will add, again, since I have become more meticulous ("fussy", if you will) about trying to keep mounting distance error as much under a millimeter as possible, I have significantly cut back on my sibilance problems.
 
P mount was designed for simplicity. Simple but good. Never designed for high end applications. For average users with average wants and needs. Not for those who wanted the best. Performed great within those sets of expectations. Biggest issue with T4p was the lack of cartridges truly designed for it rather than adapted for it. And with quite a few non adjustable turntables, a real problem. I actually favored a common alternative then which was the integrated headshell cartridges. Which was a sensible way to minimal setup time and great performance. And still allowed full flexibility and choices.
 
It is with the utmost consideration and respect for everyone involved that I would report these findings. I did not do those calculations like David did, which are most interesting, but I did take note of the effect of overhang on null points whilst adjusting a Mitsubishi table a while back. What I found is that lengthening the overhang moves the two null points closer together and shortening the overhang moves them apart. Specific to my table and arm, I found 50 mm length at the headshell to be the best compromise. If the cartridge were moved forward 1 mm it would move the inner null point about 1 cm towards the outside of the record and, likewise, moving it towards the rear or the headshell moves the inner null about 1 cm closer to the label, into the dead wax.

Now the inner null is arguably the most critical alignment point since we are dealing with a short radius and reduced velocity under the stylus (and several other issues including increasing asymmetrical lateral load due to the offset angle of the cartridge). There is a similar but less pronounced change on the outer null.

On my table an error of plus or minus 1 mm in overhang is the difference between the inner null at 60 mm verses possibly 70 mm or 50 mm.

All of these measurements are with the cartridge straight in the headshell.

I did not do listening tests to note the audible significance of these settings.

Regards to all.
 
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tubewade said:
It is with the utmost consideration and respect for everyone involved that I would report these findings. I did not do those calculations like David did, which are most interesting, but I did take note of the effect of overhang on null points whilst adjusting a Mitsubishi table a while back. What I found is that lengthening the overhang moves the two null points closer together and shortening the overhang moves them apart. Specific to my table and arm, I found 50 mm length at the headshell to be the best compromise. If the cartridge were moved forward 1 mm it would move the inner null point about 1 cm towards the outside of the record and, likewise, moving it towards the rear or the headshell moves the inner null about 1 cm closer to the label, into the dead wax.

Now the inner null is arguably the most critical alignment point since we are dealing with a short radius and reduced velocity under the stylus (and several other issues including increasing asymmetrical lateral load due to the offset angle of the cartridge). There is a similar but less pronounced change on the outer null.

On my table an error of plus or minus 1 mm in overhang is the difference between the inner null at 60 mm verses possibly 70 mm or 50 mm.

All of these measurements are with the cartridge straight in the headshell.

I did not do listening tests to note the audible significance of these settings.

Regards to all.
Click to expand...

Interesting. I've always sort of figured that, pretty much anywhere you place the cartridge, there will be two null points somewhere. It's just a question of where and what happens before, after and in between. I suppose that's why we have "competing" theories about where the best ones are.

Thanks, Wade and David, for steering us (me) back on course.

John
 
dlaloum said:
Without wanting to in-flame....

My question was quite relevant...

How much difference does 1mm in needle location make?

The answer is likely to be different for different length arms, and different again for linear trackers I would think - and it is a question of geometry and the harmonic distortion generated by tracking error.

If we found that the 1mm difference would increase THD by say 5% - then it would be something worth obsessing about and quite a potentially audible improvement.

If on the other hand we find that the difference is of the order of 0.05% THD, then it would be so completely swamped by other issues in the overall picture of the TT and system that it is absolutely not worth worrying about.

Without knowing which of the two it is (or where it lies in between the two extremes) - having a flaming war over it is a little pointless. (although emotive language is unhelpful)

Using the VE calculator (very handy: http://www.vinylengine.com/overhang...=15.14&oa=22&ty=h&n_oh=16.14&submit=calculate )

And entering the parameters of the SME 3009 series I, we find that increasing the overhang from 15.14mm to 16.14mm.... has the following effects:

Average RMS THD decreases by 0.009% (lets round it to 0.01%) - of little or no relevance.

Peak THD increases by 0.144% ... hmm it might have a marginal/subtle impact and it would be better not to add the 1mm - but it does not appear to be a major issue

Using the parmeters of the SME 3012 v1 - as an example of a longer arm:

Average THD increases 0.054% not a big deal...
Peak THD increases 0.139% pretty similar to the 9" arm


The calculator is of no use with a linear tracking arm...

So there you go is there an impact - YES
Is it worth worrying about at the lower end and midrange levels of performance - not really
Is it worth worrying about in terms of aiming for high end performance - yes it is. every little bit counts... and 0.14% THD is not a small amount of THD, most people would not purchase an amp that specced as 0.14% THD... we expect the order of magnitude of THD to be in the order of 0.01% to 0.05% typically.... (and we strive for much better)

Where you as an individual sit on this matter in terms of how important / critical it is to you depends on your audio aspirations....

I often like to compare to my uncle who listens to an old transistor radio, and asks why the hell anyone would bother spending the time and money getting something that doesn't even sound any different. (he adamantly insists there is no difference in sound quality between his transistor and any "stereo" he has heard) - clearly for him the 1mm difference in stylus position would be of no relevance.

For me - well I will check the stylus position more carefully on my p-mounts from now on.

bye for now

David
Click to expand...

With all you stated here it clarifies my point.
It's trivial in general.
Not worth fussing over.
Human hearing and room acoustics/reflections add in their own distortions much more.

Quick story:
I stopped by a friend's to discuss a matter, while standing in his living room.
At one point, I leaned my elbow on one of his tower speakers - a NORMAL human thing to do.
He immediately YELLED at me to remove my arm, stating that those speakers were "critically placed" and that moving them a fraction of an inch out of position would upset his listening pleasure.
A mere few MILLIMETERS difference from the wall would upset things?

Some people need to get a grip. :scratch2:
 
boreas said:
Interesting. I've always sort of figured that, pretty much anywhere you place the cartridge, there will be two null points somewhere. It's just a question of where and what happens before, after and in between. I suppose that's why we have "competing" theories about where the best ones are.

John
Click to expand...

I think you are right. Within reason, maybe plus or minus 2 or 3 mm, there will be two null points. The issue is whether they end up located in a useful place. Looking at graphs of tracking angle error and distortion shows us that what happens in between the nulls is good, but what happens once we get outside of the inner null is not good at all. Because of this I think that if we have some small error it would be better to have overhang that is 1 mm too short rather than 1 mm too long.

How critical this millimeter is has a lot to do with stylus profile, I think. Conical/spherical styli don't care too much about being off by a little bit since it is the same shape all around. Even .4 x .7 mil tips may not be terribly upset by less caring adjustment. Beyond that, .2 x .7 mil and finer line contact styli I do believe the location of the inner null is critical.

I hope my earlier post was not received as a reprimand to anyone as it certainly wasn't intended to be.
 
tubewade said:
Specific to my table and arm, I found 50 mm length at the headshell to be the best compromise.

All of these measurements are with the cartridge straight in the headshell.

I did not do listening tests to note the audible significance of these settings.

Regards to all.
Click to expand...

Please sir, I would like to know the model of the Mitsubishi turn table you are referring to. :music:
 
I'm at my office today, getting some personal stuff done on my day off.

I measured the p-mount cartridges I have here. The two Stantons were predictably long at 21mm, a top-of-the-line L747S and also an L500AL that was designed to track at over 3 grams. A couple other cartridges also measured at 21mm, but they are both ones where the original stylii are pretty much no longer available, so I'd be trying out replacement stylii meant for related 1/2 inch models. Among the 20mm cartridges were ones sold as Marantz, Empire, Azden, Sonus and Nagaoka (I've been playing around with induced magnet moving iron on the office system lately).

My HOMC Dynavector DV-10P measured around 19.5mm length at rest, but I put it on my SL-MA1 (something I had been meaning to do anyway, the reason it was in the cartridge drawer in my office) and suspect that the Dynavector engineers designed to to measure 20mm while under VTF. The cantilever deflects upwards quite a bit while it is playing a record. The same may be true of the Sony HOMC that I also measured as short yesterday. There's less of an excuse for going past the 20mm standard.

I've been spinning T-Bone Burnett and The Teardrop Explodes, and the Dynavector sounds a fantastic as I remember it. I've got a better phono preamp and better speakers in the office system than the last time I used it, and it makes a difference.

-----------

I know that p-mount cartridges are not the be-all and end-all of performance. On the other hand, I've had great fun and satisfaction taking the road less traveled, putting together a fairly complete collection of these cartridges, and using two p-mount turntables as my "daily drivers" for the past few years. I don't regret for one second my experiences in purchasing and testing and measuring and playing "mad scientist" with an aspect of turntable technology that most wouldn't consider. I'm sorry if that offends some other folks, but to tell the truth, the problem is theirs and not mine. I'm not in this hobby to make others happy.
 
Back to the OP's question...

To answer the OP's question, yes I like P-mount cartridges. A Shure V15LT installed on a Technics SL-7 sounds amazing. There are many opinions on the T4P design both positive and negative. Shure was an early adopter of this design and produced a full line of these cartridges over the years. Here is a link to another thread of the early Shure P-mounts:

http://www.audiokarma.org/forums/showthread.php?t=546746

One thing that I like about them is the relative ease of cartridge swapping to get a different sound. Even with P-mount cartridges that don't quite meet the weight spec, I have found that most P-mount turntables have enough fine adjustment for tracking force to compensate.

There will always be those who believe P-mounts are inherently "low-end". This is simply not the case. There have been many fine P-mount cartridges produced over the years. However, this design didn't catch on with many turntable manufacturers with the exception of Technics. That stands to reason since Technics pioneered the design. The reality is that the T4P or "P-mount" cartridge is just one of many cartridge mounting designs to choose from. That being said, fewer and fewer P-mount cartridges are being produced and that limits your choices for a brand new cartridge - much less a "high-end" one. The new P-mount cartridges being produced are for the vintage turntable market. Most of my P-mount collection consists of vintage Shure, Pickering, Technics, Stanton, and Audio Technica with NOS styli.

So why would anyone consider a P-mount cartridge? Well besides the fact that they sound great in the right application and are easy to swap, I think they are really fun and cool. For those considering getting into vinyl again or for the first time, P-mount turntables are a great choice. There are many excellent vintage Technics P-mount turntables available on the used market that are relatively inexpensive and with excellent performance specifications. Most of these will outperform new turntables at twice the price.
 
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