How are you playing your precious MONO Vinyl?

My point is that the absence of a Microgroove label on a post-1948 LP does not necessarily mean the LP doesn’t use the 0.7mil groove width.

“Microgroove” was likely a patented trade name, which is probably why you don’t see that exact word on all mono LPs dating from 1948 or later. Perhaps not all labels were licensed to use that term. 

Read the Miyajima website on w hy they offer cartridges with 1.0 mil styli. But keep in mind they’re trying to sell those cartridges.

Because it makes very little difference UNLESS you play mono with a 1.0mil stylus, I would guess. In that case there may be a slight issue with playing the micro groove, loss of extreme treble. Maybe not a big deal.

Bill, my experience is entire different from yours. Most MC cartridges do not accurately reproduce piano in either of my systems. My Koetsu Urushi and Ortofon M2000 being notable exceptions. The others are inferior to my best MMs and MIs in reproducing the attack of a piano note. And otherwise the latter are generally more”musical”.

I only said “high mileage “. Was thinking >100,000 miles. Of course different engines react differently. I would not follow Elliot’s advice with a new or near new car. Plus, I’m not a BMW guy. 

High mileage cars tend to lose a little compression and therefore lose the requirement for high octane fuel. I don’t know whether this applies to Elliot’s report or not. 

Sorry, Doggie, I was editing my post while you submitted yours. Ortofon's use of the term "dual coil mono" sounds like the kind of double talk I read when I researched the Quintet mono. In other words, it sounds like code for a bridged stereo cartridge.

The difference between what we are calling a true mono cartridge and a stereo cartridge that has been bridged to produce a mono signal in both channels is presumably that the true mono cartridge has had one of the pair of coils that serve each channel (assuming a MC design) either re-oriented so it does not pick up vertical movement of the cantilever, or there is no coil for that function. So my question really in disguise is what electrical measurement would tell you that? It is interesting that Ortofon responded to your question in the way you describe, because it was my experience a few years ago when I was investigating which cartridges are true mono, and which are not that Ortofon is very vague in describing how they derive their mono cartridges. As I recall, the description of the Quintet mono cartridge in particular was so ambiguous that one could not tell whether it was a true mono or a bridged stereotype. And I think that was deliberate. Surely the engineers at Ortofon do know the different ways to build a mono cartridge and the structural differences that result. Ortofon is not the only cartridge maker that leaves the question open or ambiguous.

Here’s a question. Suppose you have a mono cartridge but don’t know whether it’s a true mono or a bridged stereo type. How would you tell the difference?

If you look at graphs of the various curves generated by the different algorithms, they are not terribly different from one another, because after all the goal was essentially the same.  So I might be happily listening to some of my 50s mono LPs where the pre-emphasis was other than RIAA via the RIAA de-emphasis curve built into all my phono stages; I just don't hear a problem, except maybe with those Louis and Ella recordings on EMI, which date from 55 or earlier.

I don't have any phono stages with options for the de-emphasis curve.  They are all RIAA.  And since this one pair of LPs on EMI are the only LPs where I have ever noticed a possible problem, it has not and will not be worth my while to buy one.  I have several other copies of Louis and Ella both original pressings and re-issues that sound fine with RIAA.  I would wager those EMI pressings are original in the UK, because the LPs are obviously very old; the quality even of the album cover jackets is sky high. If I ever have access to a phono with options for EQ, I will give them a try.  when I was a kid, my parents had a Harmon Kardon mono receiver which did provide at least 3 curves.  I used to play with them while listening.

Not a groove expert. I only have read what I wrote, which only applies to the 33 rpm era post ~1948. 

A "two channel mono phono preamp" is any phono preamp or phono driving a linestage where the mono mode is engaged, when you feed that phono section with a true mono cartridge. Lalitk, I don’t understand exactly what you are after. If you want to go the ultimate purist route, then use a true mono cartridge with only two pins for output driving one channel of a stereo phono stage which in turn drives one of the two amplifiers driving one of your two stereo speakers, like Elliot says he sometimes does. The added advantage of the EQ100 is only the ability to select the compensation curve. If you don’t know for sure what pre-emphasis curve was originally used, then fiddling with the de-emphasis curves is pure guesswork. You might find one curve that pleases you most, but you cannot be sure it is the algorithm that was actually used in the making of the mono LP. I’ve got one set of mono LPs, Louis Armstrong and Ella Fitzgerald, the classic recordings, on EMI in mono (UK pressings), where when you play them with RIAA filtering something sounds off.  Whereas the original US pressings on Capitol (I think, or maybe Verve) sound wonderful with RIAA filtering.  I have always suspected that the EMI pressings were done differently in some way.  Of course, no matter what, the music is sublime.

"Mono LPs pressed from 1948 until the early-mid 60’s have a groove width of 1mil.  Mono LPs pressed after the mid 60’s and including current mono reissue LPs have a groove width of .07mil...a smaller groove width. "

Not that it matters much, because the point is correct but the numbers are not.  Stereo grooves are 0.7mil in width, not .07mil.  Also, I have read that the 1mil groove went out in the late 50s or even earlier, not the mid 60s, but that factoid was not documented any more than is the claim it went out in the mid 60s. There was a period of time in there when top artists recorded the same material both in mono and in stereo, two entirely separate recording sessions. For example, I have a recording by June Christy, "Something Cool", separate versions in mono and stereo.  Same album cover, same sequence of songs on each, but if you listen to both, you can easily hear differences in phrasing of lyrics and in the improvisations. Both on Capitol. One wonders whether there is any difference in groove width between the two versions and whether an LP side with 1.0mil grooves for mono would have to contain fewer minutes of music than a corresponding recording in stereo which has to use 0.7mil grooves (because 1.0mil grooves would take up more space).  I am sure there is someone out there who knows.

"Some believe that the presence of vertical content that is then summed introduces distortion and phase anomalies that are audible."

Whether or not such distortions are "audible" is a matter for belief or individual acuity, but whether there is distortion and phase anomalies introduced by bridging a stereo cartridge to produce a mono signal or by using the mono switch on a linestage ought to be measurable, in other words a matter of fact, not belief.  Does anyone know of any published science on this subject? Preferably, the results would be compared to those obtained using a "true mono" cartridge on the same program material or a test LP.

Elliot, You wrote,

"Everyone, 

the Aurorasound EQ-100 is uniquely different, from the manual:

"When a stereo cartridge is used, any vertical signal on a record is cancelled by an internal circuit of EQ-100. Only the R+L horizontal signal are detected to assure a superior sound stage with less noise."

Cancelling any vertical input seems to me FAR better than producing the noise and then summing the noise in both channels, that is my biggest objection and what I referred to as MUD on top of the Mono Content (Dual Mud?)."

First, the long sentence about how the Aurora works can be applied to any stereo preamplifier when the mono switch is activated. That is what they all do, and that is why HF noise from the LP surface irregularities is reduced, not enhanced, compared to playing a mono LP in stereo mode with a stereo cartridge.  Then in your second paragraph you revert back to this idea of "summing". Just forget it. It's a semantic twister. None of this is to say that I disagree with your contention that using a mono cartridge is superior to using a stereo cartridge plus mono switch. I am in no position to disagree, because I don't use a mono cartridge at all.  Although I do own a Shelter mono cartridge that has been sitting in a box for about 5 years.

For you guys who do use a mono cartridge to feed a stereo phono stage, consider that the two channels of your phono are unlikely to be absolutely identical in all measurable aspects of their performance. Thus the output from one channel may differ very slightly from that of the other channel, thus introducing, say, phase differences or slight differences in distortion or frequency response. Thus there could be an audible difference possibly between activating the mono switch and not activating it. And results might differ from one system to another, particularly because humans are reporting on what they hear. Nevertheless, I urge those of you with mono cartridges to try it both ways, mono switch on vs mono switch off, and report back.

Using a stereo cartridge on a mono LP is not going to harm the LP.  No way. You won’t get the best possible SQ, but there is no harm done.  However, many stereo LPs marketed at the dawn of the stereo era do say on the back of the cover, usually in small print, not to use a mono cartridge, for the reason mentioned already, the lack of vertical compliance of most mono cartridges of that era might damage the groove walls that carry stereo information.

For the umpteenth time, using a mono switch when playing a mono LP with a stereo cartridge is not per se going to increase noise because of "sum"-ing. Phase cancellation takes care of that, and reduction, not summing, of common mode noise is the principle benefit of using the mono switch.

Define “early”, because that’s where there is lots of controversy.

What is "EQ-100"?

If you think you have a true mono cartridge, do try with vs without the mono switch engaged and let us know what you hear. At least some of the Beatles LPs originally came out on Parlophone in the UK and were mono to begin with.  However, since the works are from the 60s, it is quite likely that modern RIAA equalization was used. I have never read otherwise.

I hope I did not say there are no "true" mono cartridges. I only refer to the type described. Still, the second caveat for comparing is valid; your particular mono cartridge may just be "better" or "worse" than your particular stereo cartridge. Therefore any conclusions are subject to that qualification. I do think even using only a mono switch when playing mono LPs with a stereo cartridge is superior to not using the mono switch.  At least in that comparison I am not using two different cartridges. If you want to get really purist, you can use one of those few mono cartridges that only has two pins and use it to drive only one channel of your stereo system. I've never tried that nor heard it on someone else's system.

This subject has been rehashed many times.  Many of the mono cartridges on the market are nothing but stereo cartridges in which the two channels have been bridged internally. The mono switch on a linestage also achieves mono output into both channels by virtue of bridging the two channels at the output.  So, when comparing this type of mono cartridge to the mono switch, the only difference is that in the one case the two channels were bridged before RIAA correction and amplification; whereas in the other case the mono signal is created after these processes take place. I could imagine reasons why either one is better than the other.  The other factor is that when you use a mono cartridge and compare it to your stereo cartridge, unless you are using the artificially created mono version of the very same stereo cartridge you are otherwise comparing two different cartridges.  Any two cartridges can differ in sonics by virtue of many factors, so it is hard to say in that case that "a mono cartridge is per se better".