How Phono Cartridges Work

[Frank Dernie]

Neither a MM or MC, the London Decca ...

I like the Decca sound. I have never seen measurements but when at a friend's who has a very expensive Allaerts MC in one arm and an old Decca in a simple unipivot in another arm on the same Verdier TT my wife, a professional musician, asked in all innocence why he ever used the Allaerts when he played both...
I have a Decca and a Stanton in the 2 headshells of my EMT TT, but it is in storage.

 

[watchnerd]

I like the Decca sound. I have never seen measurements but when at a friend's who has a very expensive Allaerts MC in one arm and an old Decca in a simple unipivot in another arm on the same Verdier TT my wife, a professional musician, asked in all innocence why he ever used the Allaerts when he played both...
I have a Decca and a Stanton in the 2 headshells of my EMT TT, but it is in storage.

I've heard they can sound incredibly dynamic with fast transients....but I've also heard they're really finnicky in terms of matching arms and also incredibly unreliable....

 

[Frank Dernie]

I've heard they can sound incredibly dynamic with fast transients....but I've also heard they're really finnicky in terms of matching arms and also incredibly unreliable....

Indeed. The current ones, sold as London cartridges since they bought the rights from Decca, are not so unreliable.
The sensing element is almost directly connected to the stylus, rather than at the end of a thin rod a long way (in HF vibration terms) away. This has a benefit for accuracy but the body to disc surface clearance is minimal, so some big warps are said to touch the body (none of my records have been that badly stored) and any dust build up will lift the stylus out of the groove.
It is definitely a transducer for the fastidious!

 

[watchnerd]

Indeed. The current ones, sold as London cartridges since they bought the rights from Decca, are not so unreliable.
The sensing element is almost directly connected to the stylus, rather than at the end of a thin rod a long way (in HF vibration terms) away. This has a benefit for accuracy but the body to disc surface clearance is minimal, so some big warps are said to touch the body (none of my records have been that badly stored) and any dust build up will lift the stylus out of the groove.
It is definitely a transducer for the fastidious!

What's the weird 'pod' mounting system?

 

[Frank Dernie]

What's the weird 'pod' mounting system?

Not familiar with it. Mine is a bog standard super gold. As a vibration research engineer and ex- record player designer I am not impressed by stories of rigidity, so if you mean the clamp block people used to use I am not convinced it is needed, though it may make a difference in where resonance shows up in the frequency domain.
I would like to try this:
http://www.thecartridgeman.com/isolator.htm
it makes complete sense from a transducer pov but it is too expensive and fiddly to try for the few occasions I play an LP.

 

[TBone]

He's an interesting factoid I haven't seen anywhere else:

Nagaoka doesn't publicly disclose the minor / major radii of the MP-500 anywhere, calling it a "Superfine line contact" or "highly polished line contact", which could be almost anything.

You are correct, I looked thru all my Nag docs to confirm, and unless otherwise stated in Japanese, it not disclosed. Yet, the specs for the MP30 on down were made available.

I contacted Nagaoka technical support in Europe, they sent the question to Japan, and they finally answered.

The minor radius is 7 microns; they didn't disclose the major radius.

7 microns = 0.275 mil. Round it up to 0.28.

Thank you for doing the above research. Too bad they didn't provide R.

The MP50S stylus looks like a Shibata variant under a micro, perhaps a little thinner back to front, and was listed as a "Super-Elliptical". No radii specs are available (to my knowledge) but I always assumed r=~6microns, R=~60microns. That's in contrast to r5, R120 of my last cartridge stylus (FG-S).

That said, a little surprised the MP50 r=7um microns, perhaps a tad large compared to the likes of the Ogura PA (r3um R35um) and Namiki micro-ridge types (r2.5um R70um) but they represent the extreme in terms or minor r.

Which also happens to be the minor radius of all the Audio Technica cartridges that use a "Special Line Contact" stylus, namely the TOTL cartridges in each of their respective ranges: ART 1000, ART 9, ART 7, and VM760SLC.

Interesting.

Brilliant marketing by AT, by the way, to relegate the main competition's mass market top stylus shape, the Ortofon black series Shibata cartridges (2M Black, Quintet Black, Cadenza Black) to 2nd tier in the AT line-up (AT33Sa is just below the ART 9 in price, the VM750SH is just below the VM760SLC), and then bump the line contact up to 1st tier.

Which then raises the question of why they moved the Micro Line styli to last place....possibly to "downgrade" the comparison to Jico SAS?

Stylus cuts all represent certain compromises. A large R, such as the Replicant, FG-S, VDH requires very precise azimuth, which unless you have a way of holding down an LP - perfectly flat - to a perfectly flat platter, the odds are it will rarely perform optimally(*). Vinylphiles who don't care about azimuth setup, or who just want to minimize such issues and "just" play records are much better off w/less aggressive contact stylus.

(*) not only will they not perform optimally, azimuth issues related to large contact stylus types also introduce other issues (> drag & resonance) that WILL negatively affect how an the arm and turntable perform. Needle talk (the lack of) is often a very good indicator of proper setup and cartridge/arm/turntable capability.

 

[TBone]

As a vibration research engineer and ex- record player designer I am not impressed by stories of rigidity, so if you mean the clamp block people used to use I am not convinced it is needed, though it may make a difference in where resonance shows up in the frequency domain.

IME, the most "rigid" arm(s) both measure and sound better.

 

[solderdude]

Yup, pretty much spot on. The microscope was a low-power stereo vision model like we use for assembly of those teensy SMD's these days, and electronic tweezers and such plus some tools from my dad's (PhD microbiology) lab. Might as well have been medical tools. Very fine wire, magnets robbed from another cartridge, ditto cantilever and stylus, and several types of glue were tried (I think this was before superglue was common, but some reagents from my Dad's lab were essentially the same thing). I tried using a Dremel to spin the cantilever and wind the coils; managed to break a few along the way (cantilevers, not Dremels, though Dremels are pretty rugged based on some minor bit of frustrated experience). Before I was done I was wishing I had a scalpel, not sure if I would have used it on the cart or myself... I did get it to work but decided I was no Koetsu maker.

You could ask Salavat Fidai maybe he can give some 'point'ers
(YouTube the guy)

 

[Sal1950]

I contacted Nagaoka technical support in Europe, they sent the question to Japan, and they finally answered.

The minor radius is 7 microns; they didn't disclose the major radius.

7 microns = 0.275 mil. Round it up to 0.28.

Quite possible they just made something up to appease you?

 

[TBone]

Quite possible they just made something up to appease you?

Highly unlikely, that number aligns well within their line, and given all my Nag literature, they've proven quite "honest" in terms of claims and specs, especially stylus longevity.

 

[Sal1950]

Highly unlikely, that number aligns well within their line,

That's why it's believable. LOL

 

[TBone]

That's why it's believable. LOL

7microns makes perfect sense for a line-contact type consider the MP30 elliptical stylus specs. And please stop suggesting they made up such a claim unless you can back it up with something, ANYTHING! ... (and especially considering that number isn't especially flattering).

 

[Sal1950]

7microns makes perfect sense for a line-contact type consider the MP30 elliptical stylus specs.

I'm just teasin ya bud.
Been reading too many power cable threads and other lunacies over at CA.

 

[TBone]

Well, I've read 1 too many pipe smoking lunacies here also, so ... you know ... doesn't mean we still can't fish together.

 

[Frank Dernie]

IME, the most "rigid" arm(s) both measure and sound better.

IME the most rigid arms, particularly if there are no lossy joins, produce resonances big enough to be seen on the cartridge output. The more rigid the arm the higher in frequency will be the transmission band of vibration from plinth to cartridge body - which will also produce output from the cartridge.
I used to measure these things for a job but haven't for years. A cartridge is a seismic vibration transducer and once the input frequency to the stylus is ~2x the Fn of the effective mass on the cartridge compliance the only spurious rubbish appearing on the cartridge output has come either from the arm or along the arm to the cartridge body, which in an ideal transducer should be stationary relative to the groove.
There is an awful lot of static thinking and discussion goes on about record players, which is not sound (see what I did there?) science. Rigidity is one of them. Nothing is rigid over the whole audio frequency range.
IME there are very, very few record players which accurately pick up what is in the groove and transmit that, and only that, to the cartridge output.
It was often said back in the day all a turntable has to do is rotate at 33 ⅓ rpm. The engineering problem is getting anything which does just that and not lots of other undesirable things as well...
Not many do IME and I haven't seen many new ones, based on what I learned when doing it myself, which impress me.
Record players are mainly a fashion business nowadays (IMHO)

 

[TBone]

IME the most rigid arms, particularly if there are no lossy joins, produce resonances big enough to be seen on the cartridge output. The more rigid the arm the higher in frequency will be the transmission band of vibration from plinth to cartridge body - which will also produce output from the cartridge.

Arms all measure differently, and resonance is not simply a rigid based issue. Tonearms with internal springs, lots of accessories or do-hickeys attached, tend to measure worse when compared to more rigid and simpler alternatives.

Miller research includes many such cumulative resonant decay plots ...

Above is the SME V, not nearly the "best" in terms of measured performance, but never-the-less - very highly regarded.

(the IV is the much better sounding arm, but not really my cup of tea(IMO)).

I much prefer simpler/rigid arms, mine specifically, so agree to disagree.

Record players are mainly a fashion business nowadays (IMHO)

That we can certainly agree.

 

[Frank Dernie]

Arms all measure differently, and resonance is not simply a rigid based issue. Tonearms with internal springs, lots of accessories or do-hickeys attached, tend to measure worse when compared to more rigid and simpler alternatives.

Miller research includes many such cumulative resonant decay plots ...

View attachment 15135

Above is the SME V, not nearly the "best" in terms of measured performance, but never-the-less - very highly regarded.

(the IV is the much better sounding arm, but not really my cup of tea(IMO)).

I much prefer simpler/rigid arms, mine specifically, so agree to disagree.



That we can certainly agree.

I considered the measured cartridge output, not headshell accelerometer, to be the more important measure, since whatever the arm looks like on its own looking for minimum spurious cartridge output as a measure of goodness. If a vibration in the arm doesn't effect output of the cartridge it isn't a problem IMO.
I believe you have an Alphason, which is a fine arm. I haven't measured it though
I know the SME is well regarded, but that is what I mean about static thinking in record player design. The SMEs I measured were the worst arms for spurious cartridge output, beautifully made but not a good bit of engineering understanding IMO, more marketing fashion. I was hired because I was a specialist in transducer design and the record players, particularly cartridges, I looked at were not very accurate as vibration transducers. Nothing much important has changed in the last 40 years IMO.
I still have my record players but don't use them much (only one is connected at the moment). I don't listen to much pop music so the biggest shortcomings of modern digital releases aren't a problem to me, so I listen to around 5 hours of digital a day and about 30 minutes of LP a month.

 

[TBone]

I considered the measured cartridge output, not headshell accelerometer, to be the more important measure, since whatever the arm looks like on its own looking for minimum spurious cartridge output as a measure of goodness. If a vibration in the arm doesn't effect output of the cartridge it isn't a problem IMO.

In my experience, that is one BIG "if" ...

I believe you have an Alphason, which is a fine arm. I haven't measured it though

Miller measured the HR100 (mk2 version) around 4 years ago. One of the most rigid arms ever made.

I know the SME is well regarded, but that is what I mean about static thinking in record player design. The SMEs I measured were the worst arms for spurious cartridge output, beautifully made but not a good bit of engineering understanding IMO, more marketing fashion. I was hired because I was a specialist in transducer design and the record players, particularly cartridges, I looked at were not very accurate as vibration transducers. Nothing much important has changed in the last 40 years IMO.

Very interesting stuff Frank, thanks for sharing. I'm was not surprised the V measured poorly, I always found this arm to sound compromised (dark & resonant) in comparison to the Alpha. I always get a kick when the typical SME fan-boys, particularly at WBF, debate about the SME's as being "reference" arms. As good as they are ... they have never measured well, and hence, I consider (the V in particular) as perhaps one of the most over-rated arms in history. But don't tell the boys at WBF, they'd only pretend otherwise ...

 

[Frank Dernie]

In my experience, that is one BIG "if" ...

That was why I measured the cartridge output itself - so there was no if. The Miller data is interesting but wild speculation is required to guess what the influence will be.
Relatively simple arms without doodads stuck on give the most accurate output IME, nice press fit junctions give a lot of helpful damping. Made from one piece ones do not have much inherent damping at all. The fashion for one piece arm/headshell combinations was not based on a good understanding of the requirements of an accurate transducer, but it was/is a long lasting all pervading fashion.

 

[TBone]

Relatively simple arms without doodads stuck on give the most accurate output IME, nice press fit junctions give a lot of helpful damping.

Well ... perhaps the black art of sinking/damping any particular tonearm is proprietary to the unit itself.

Whatever arm you may prefer, IME, it really isn't all that complicated to decipher ... if you consistently hear a lot (or even a little) of needle-talk from the cartridge, your rig is either wasting precious energy or is overtly resonant.