Mono cartridge classification

Thanks for checking me, Pryso. I need it! Still learning.

Here is a post by Jonathan Carr of Lyra that says Lyra listened to a wide range of mono recordings in developing their stylus. He says the records were both pristine and well-worn, but he doesn't cite the eras they represented. I assumed that by well-worn, he meant they listened to records from many eras, but he doesn't explicitly say that:

http://www.audioasylum.com/cgi/t.mpl?f=vinyl&m=418745

About Grado, I was careful to say that they produce a mono signal. As you said, I believe they are "mono carts" in that they are strapped to sum the L and R signals. Like you, I believe I've read that they do have vertical compliance, but I can't be sure. So they probably can't be considered TRUE mono carts like the Denon DL-102.

For your last question, the KAB website states that the KAB/Ortofon OM-1M is a stereo cart with a 1.1 mil stylus for mono playback. I believe this cart is the same as or similar to the Ortofon OM D25M, but I may be wrong about that. Do you know for sure?

I wish I had time to track down and post all the references I've drawn from——but I don't. So I hope others like you will continue to fact-check me. Not that we'll ever solve all the contradictions of mono! THANKS.
-Bob

Hesson11, thanks for the link to Carr's information. Nothing like going to the
horse's mouth! Here is information I posted on VA some time ago. Mr. Carr's
information seems to correct part of that -

"I believe you must first consider which records you will be playing before
buying a mono cartridge. From reading I've done, here are my conclusions.
Note this applies only to 33 LPs, not 78s. Dates refer to master cutting, not
performance date for reissues. This is a function of the groove shape created
by the cutter head.

Pre-stereo era monos (roughly '48-'57), select a 1.0 mil conical stylus.

Early stereo era monos (roughly '58-'68), select a 0.7 mil conical stylus.

Recent mono reissues (mid '90s to present), select a mono cartridge with a
modern narrow stylus profile.

Lyra may have been the first to promote narrow profile stylus tips for better
performance in mono cartridges. I suggest this may be true for playback of
the many mono reissues, but not as good for older originals. I've heard that
mono cutter heads are no longer available so reissue monos are now cut with
stereo heads, but with lateral motion only. This is not to say a mono cartridge
with a narrow profile stylus would not sound OK on earlier pressings, it
simply would not be optimal."

I've since purchased a mono Denon 102 but installation awaits the
completion of a new plinth for a two-arm table.

I'm not familiar with Ortofon cartridges so no help from me there.

If you think there are lots of contradictions with mono lps, start doing some
research on 78s! I have a 4-record 78 album of Louis Armstrong and the All
Stars at Town Hall, a very famous concert from 1947. I began researching 78
cartridges and that is where the waters really become muddy, and deep.
You've got to add speed and EQ variations to the various tip dimensions. At
least the situation was a little more standardized by the late '40s for my
album.

Thanks, Pryso. Your understanding of which styli to use for which recording era matches mine. Perhaps I got it from you! Have you checked out the Esoteric link I posted above? There's some pretty good info there that seems to match yours (and it's pretty clear, too!).

I'm confused enough about mono, so I'm scared to even think about 78s!

Not to open another can of worms, but do you use any kind of equipment to match the pre-RIAA EQ curves (Esoteric Re-Equalizer, KAB Souvenir, etc.)? I just use the tone controls on my integrated amp, at least for now. Works pretty well.

-Bob

Hesson11, I've looked into EQ devices, including the Re-Equalizer, but have not purchased anything as yet. I began a major change in my system last year, going to HE speakers and a 300B PP amp. I've also picked up a few cartridges following inspiration from Raul's lengthly post. But one component at a time, and after I settle on an amp (still evaluating), I'll choose a new preamp/line stage, then decide on the EQ. I don't have anything with tone controls but I've read they can work fairly well.

I do have several hundred mono LPs so optimizing their playback will be a high priority. Thanks for your interest and adding your thoughts.

As seen from the front, the 70~75um radius stylii that we (Lyra) use on our mono cartridges are anything but narrow, and are intended to "fill up" the LP groove as completely as possible without requiring a fiendishly accurate setup which would be too difficult for most users. "Long contact patch" is a much better phrase to describe these stylii than "narrow profile" (which is a completely wrong phrase to describe our engineering choices). However, as seen from the side, these stylii are narrow (2.5~3um), because to be otherwise would create unnecessary time-smear (at best), and at worst would result in impaired ability to track high frequencies. The grooves of vinyl LPs are able to withstand 2.5um~3um, but styrene records should be played with larger side-radius stylii.

In our mono cartridge testing, we've played everything from Microgroove LPs from the late 1940s, to mono LP's from the 1950s, to modern mono LP reissues. In all cases I've felt that a properly dimensioned wide, long-footprint line contact stylus gave much better results than traditional options like 1 mil or 0.7mil spherical stylii.

Our hands-on testing has not shown that a properly dimensioned wide, long-footprint line contact stylus is particularly sensitive to the width of the groove. What we have seen is that the important parameter that changed over the years is groove depth. Groove angle would also be important if it varied according to the time of LP pressing, but the groove angle of a Microgroove LP (as well as modern LPs) is defined to be 90 degrees, and as long as it doesn't deviate from 90 degrees, the stylus will simply keep its natural distance (as defined by the stylus shape) from the groove bottom. The stylus should therefore have no problem with remaining in full contact with the groove walls or tracking, regardless of groove width. But if the groove bottom is shallower than the groove width would suggest (which could be the case with earlier Microgrooves and mono LPs), or filled with dirt (not an uncommon condition with second-hand mono records), the tip of the stylus may "bottom out" if it is too acute and/or goes too deep.

Our mono stylii retain a long contact patch with the groove wall, which is essential for top performance, but are designed to not go so deep into the groove and therefore don't get into problems with grooves that are shallower or filled with dirt.

hth, jonathan carr