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True mono cartridges, damage modern mono records?

108.16.52.21
Posted on July 27, 2014 at 09:41:04
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 Recently I've been exploring the wonders of mono playback with the help of a Miyajima Zero mono cartridge. With all the similar discussions I've found I haven't been able to come up with a clear answer to this question: will a true mono cart like the Zero, with no vertical compliance, damage post 1967 mono records that were cut with stereo lathes? I know it works on reissues, and I know it sounds great, but could I be doing any damage to the grooves? If a cartridge is designed for a true U shaped groove, will it destroy a V shaped groove over time?

 

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RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 11:08:48
John Elison
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Posts: 23900
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since: January 29, 2004
 I thought all grooves were V-shaped. Where did you get the information that some are U-shaped?

The difference between mono and stereo grooves is that mono grooves are laterally modulated only whereas stereo grooves are both laterally and vertically modulated. A mono LP cut with a stereo cutting head will have no vertical modulation unless the channels are out of balance and/or out of phase. In other words, if the dual mono signals sent to the stereo cutting head were out of balance and one channel was louder than the other, this would cause vertical modulation. Also, any phase differences between channels would cause vertical modulation.

Best regards,
John Elison

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 11:25:26
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 The U thing may or not be a misconception, it's another topic that seems to be debated on various forms. Let's just assume I'm wrong about that. You're saying, I think, that even if a mono record is cut with a stereo lathe, there shouldn't be any vertical information, so there's nothing for the stylus do damage. Is that correct?

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 11:37:59
John Elison
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Posts: 23900
Location: Central Kentucky
Joined: December 20, 2000
Contributor
  Since: January 29, 2004
 > You're saying, I think, that even if a mono record is cut with a stereo lathe,
> there shouldn't be any vertical information, so there's nothing for the stylus do damage. Is that correct?

Yes, that is my opinion.

Good luck,
John Elison

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 11:55:41
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 Thank you very much John.

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 13:25:00
M3 lover
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Posts: 6604
Location: SW Mich
Joined: May 29, 2005
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  Since: July 4, 2007
 Hi jtycho,

Like JE, I'm unaware of records cut with a U groove.

In the late '50s and early '60s, during the transition from mono to stereo, many labels published warnings against playing stereo LPs with mono cartridges. I believe this was because of the 3 mil mono stylus and the potential for damaging the more delicate (finer undulations) stereo groove with the larger tip. This had nothing to do with compliance. The mono cartridge coil and magnet were arranged to read only lateral movement.

But the reverse was OK, mono recordings could be played back with stereo cartridges without damage. They may not sound the best but no harm should occur.

All this relates to another question for which I've not seen a clear answer. I've read that old mono cutter heads were not replaced so modern reissues of mono recordings are now cut with stereo cutters. In addition at least some of the current mono cartridges have low profile styli, similar or equal to their stereo siblings. OK, just like in the '50s and '60s, these smaller, stereo styli can play older mono LPs without damage. But can the newer reissued mono LPs be played by true 3 mil mono styli without fear of damage?

"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 13:30:45
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 With no first hand evidence, I believe the answer to your question is definitely a NO. I'm pretty sure even if you wouldn't damage the record the sound would not be optimal, making it pretty pointless to take that risk.

 

True mono cartridges "Miyajima Zero" anyway does NOT damage modern mono records. IME, posted on July 27, 2014 at 14:26:29
David M.
Audiophile

Posts: 150
Location: Big D Texas
Joined: October 9, 2002
 I also have a Miyajima ZERO and initially had the same question / concern. After direct consultation with industry experts, and based on my own listening and playback experiences, it is my opinion that the ZERO in no way damages modern Mono LPs or mono reissues. In fact after hearing some of Chad's work with the MONO Prestige Series using my ZERO, I ordered the whole series. It is that spectacular. I have played several mono reissues many many times and they still sound fantastic. Conclusion...No Damage at all!

 

RE: True mono cartridges "Miyajima Zero" anyway does NOT damage modern mono records. IME, posted on July 27, 2014 at 14:54:23
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 That's very comforting. I too have some of the Prestige reissues and they are indeed fantastic. At $30 a pop I feared doing some damage! Have you heard the next batch of Zeros will all have a 1 mil stylus, I wonder why the change?

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 15:05:04
coffee-phil
Audiophile

Posts: 1444
Location: Shingle Springs CA
Joined: January 7, 2010
 Hi M3 lover,

Like you and John, I am unaware of a U-shaped Lp groove.

I do have to take issue with what you said about the 3 mill stylus and compliance. The 3 mill stylus is for 78 RPM standard groove records. The Lp records which came out in the '40s were also called micro-groove records and were to be played with a one mill stylus. At this time both standard groove 78s and Lps were lateral cut hence no need for vertical compliance in the pickup. Classic mono pick-up cartridges such as my GE RPX often had both 3 mill and one mill styli and little or no vertical compliance. These are the cartridges which must not be used on stereo records. With the advent of stereo the groove got slightly narrower and 0.7 mill styli became standard. They also work fine on mono records.

I would expect that even a classic mono cartridge would be safe on a mono record cut with a stereo cutter if the channels are balanced.

More recently "modern" mono cartridges have appeared. Many of these while not responding to vertical motion of the stylus do have vertical compliance and are therefore "stereo record safe". The example which the OP gave is to me a bit unknown. There is no clear explicit statement on vertical compliance or stereo record safety on their web page.

Phil

 

RE: True mono cartridges, damage modern mono records?, posted on July 27, 2014 at 15:23:44
jtycho
Audiophile

Posts: 112
Location: philadelphia
Joined: December 10, 2007
 Somewhere on their website it mentions the lack of vertical compliance and that their mono cartridges will damage stereo records.

 

Ah, should not engage mouth (or typing fingers) without first checking with brain!, posted on July 27, 2014 at 15:47:17
M3 lover
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Posts: 6604
Location: SW Mich
Joined: May 29, 2005
Contributor
  Since: July 4, 2007
 You're right of course and I'm glad you corrected my post. I know better that the 3 mil were utilized with later 78s while LP styli are 1 mil or smaller.

I was not certain about vertical compliance in older mono cartridges so thanks for that.

I have read from J. Carr, designer for Lyra, about benefits from their modern styli profile in their mono cartridges. And while that may be true for the number of mono reissues produced over the last several years with stereo cutter heads, I still wonder how optimum that might be with original monos from the '50s and '60s?

I bought a Denon 102 true mono cartridge a while ago but have been delayed installing it in the intended arm/table. I do have several hundred mono LPs from the '50s and '60s as well as nearly 100 45s so I look forward to that.



"The secret of life is honesty and fair dealing, if you can fake that you've got it made." Groucho

 

RE: Ah, should not engage mouth (or typing fingers) without first checking with brain!, posted on July 27, 2014 at 16:30:22
coffee-phil
Audiophile

Posts: 1444
Location: Shingle Springs CA
Joined: January 7, 2010
 Hi M3 lover,

From what I read you should love that cartridge. It has the advantage of being safe for stereo records while having good vertical rejection. With my RPX I have to be careful to not play a stereo record with it. I can run my stereo cartridges into my mono phono stage and sum in phase for lateral or out of phase for vertical. If there is a question about a record I play it with a stereo cartridge in vertical first. If I hear much it does not go under the RPX.

Phil

 

1 mil is standard, posted on July 27, 2014 at 18:07:58
David M.
Audiophile

Posts: 150
Location: Big D Texas
Joined: October 9, 2002
 Obviously the tip would ride a little bit higher in the groove? Maybe Robyn will let us know? I can say that as is it is / was at (.7MM) it is astonishingly quiet in the groove and the sound is superb. Maybe if the difference is enough when we get our second ZERO it will ride on new vinyl on our old LPs and make them new again? I am sure I have played my Prestige Colossus 10 times and it amazes me every time...Dead quiet

 

Pinch effect and vertical compliance, posted on July 29, 2014 at 18:44:45
Charlie S in Maryland
Audiophile

Posts: 34
Location: Maryland
Joined: July 29, 2014
As the stylus tip traces lateral mono groove modulation there is some vertical motion due to "pinch effect". This is primarily at the higher frequencies, and is due to the effective groove width being reduced by the modulation peaks. All quality mono cartridges allowed for this by providing for some vertical tip displacement. Otherwise, serious groove damage would occur. (Even the early acoustic phonographs had a bit of vertical compliance due to the needle being slanted backward.)

Vintage examples of mono pickups I'm familiar with include the GE VR RPX series, the ESL MCs, and the Weathers FM pickup. These all had some degree of vertical compliance, but did not produce any ELECTRICAL output from vertical motion. This is as desired, since the vertical pinch effect motion is dominantly second harmonic distortion. [By listening only to the difference between left and right outputs of a stereo cartridge (i.e., making its output sensitive only to vertical motion) while playing a mono record, one can hear the pinch distortion.]

Stereo groove modulation in the horizontal direction (center-stage sounds) also produces pinch effect distortion, which does appear in the left and right channel electrical outputs. A reduced tip scanning radius (i.e., 0.7-mil or smaller) minimizes the pinch effect distortion. This is the reason for playing stereo records with a smaller tip radius.

I have no first-hand experience with modern "mono" cartridges, but I hope they have SOME vertical tip compliance -- while being electrically insensitive to vertical tip motion. Otherwise, it would necessitate the entire arm to move vertically to accommodate the pinch effect – the vinyl would give way first! However, the pinch motion is predominantly at higher frequencies and of low amplitude, so the needed vertical compliance is required only for small displacements.

Personal opinion: As far as groove tracing, I see absolutely no technical disadvantage to playing mono LPs with a stereo cartridge, provided that the left-right outputs are summed to mono somehow to cancel sensitivity to vertical tip motion. Indeed, at least one modern so-called mono cartridge is really a stereo generator design with the left and right channel generators internally strapped together.

Incidentally, my recollection is that the Library of Congress is digitally archiving their collection of historic mono records (both LPs and 78s) using stereo cartridges (fitted with appropriate radii tips).

Charlie

 

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