Mono cartridge classification

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

Thanks so much for the information, Jonathan. Glad we're no longer talking behind your back! I'm glad you cleared up the question on which types of records you used in developing your stylus shape. I've certainly never heard of anyone doing such extensive comparisons of stylus shapes with mono records, so your findings are especially valuable.

Am I correct in understanding that you now use that stylus shape on ALL your cartridges, both stereo and mono?

I hope we haven't scared off our original poster, but I fear we have!

-Bob

Hey sorry I'm late to the party.

The Ortofon CG 25 DI MKII and CG 65 cartridges are SPU-styled (although SPU technically stands for Stereo Pick Up). Some places refer to these as MPU cartridges (M meaning 'Mono').

The CG 25 has a 25 micrometer diameter conical diamond, and the 65... Well, 65 micrometer. 25um is best for your general mono/microgroove recordings whereas 65 is for 78rpm recordings. These are TRUE mono designs built as closely to the original mono cartridges from the 1950s/60s. The SPU Mono GM MKII, by contrast, is a strapped design - it's a stereo cartridge wired to run in mono.

Yes, Lyra has some very interesting diamond profiles, and for some people this will be the ticket to high performance reproduction of mono recordings.

Ortofon feels that the CG25 and CG65 represent the true artisan style of playback of mono recordings, and consequently these cartridges find their way primarily in modern-vintage systems with removable-headshell-style tonearms. Your Thorens, Garrard, etc crowd. You might not get a highly detailed listen, but mind you these cartridges are designed to provide everything but the HiFi sort of sound. They're meant to provide body, rich and syrupy midrange, and slam.

Depends what you like... Lyra also makes a stellar product.

I work for Ortofon.