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It is my understanding that the only difference between the Bach 18 mouthpiece and the Bach 12 mouthpiece is the inner diameter. The Bach 18 has a 32.10mm diameter and the Bach 12 has a larger 32.75mm diameter. (I realize that actual production spec consistency is not a hallmark of Bach mouthpieces. However, I am simply going on published specs.) Anyway, if you go to the Kelly mouthpiece web site, the inner diameter specs they give for the Kelly 18 is 1.285 inches, which converts to 32.6390mm. If this is true, isn't the "Kelly 18" closer to, or more appropriately, a "Kelly 12"? Just curious if I am missing something here.

You are probably right, but the difference between the Kelly 18 and Bach 18, using your measurements, is .539mm or .021". Hardly enough of a difference to matter.

You are probably right, but the difference between the Kelly 18 and Bach 18, using your measurements, is .539mm or .021". Hardly enough of a difference to matter.

I would tend to agree. I am never sure how much of a spec differerence is required to make a difference in the real musical world. However, I have read many posts on this site that sing the praises of one mpc over another where the difference in specs seemed pretty insignificant to me (not taking into account the complex holistic compostion of a mpc). Also, the difference in the inner diameter of the Bach 18 vs. Bach 12 is only .650mm, only slightly more than the .539mm difference between the Kelly 18 and Bach 18 that you site in your observation. That begs the issue if there is much of a real world difference betwen the Bach 18 and Bach 12 (or if there is an element of marketing in the number of mouthpiece sizes that many manufacturers produce). Concerning the Bachs, I do not know. I have never tried a Bach 12 to compare it to my Bach 18 to discern what, if any, differences may exist.

Assuming the 'cup' dimension is the tangent point where the inner sidewall of the cup meets the radius on the inside of the rim... that's REALLY difficult to measure without EXPENSIVE coordinate measuring equipment. I have a Kelly 18, a Bach 12, a Bach 7, and a Kelly 50 (PT-50 copy)....

Kelly 18.... 1.299"
Bach 12.... 1.292"
Bach 7.... 1.312"
Kelly 50... 1.337"

I play all of these MP's.... using the Kelly 50 more than the rest. I can tell you that as far as how these MP's feel on my chops, the Kelly 18 and the Bach 12 seems to be very much the same.

I don't have the specs on these MP's so I don't know what they are advertised to be.

Dan, your inner diameter measurements are quite close to the published specs for the Bach 12 and Kelly 18 mouthpieces. And your sense that those two mpcs feel similar would seem to be supported by the similar inner diameter measurements.

A quick question if you don't mind. One of the mouthpieces I use with my King 1241 is the Bach 18. I am thinking about trying the Bach 12. What are your thoughts on the 12?

TubaBobH wrote:...... A quick question if you don't mind. One of the mouthpieces I use with my King 1241 is the Bach 18. I am thinking about trying the Bach 12. What are your thoughts on the 12?

For Dixieland stuff I play a modified old-style 2341. I used to use a Bach 18 most of the time. I bought a Bach 12 thinking I might like it better. I used it for a while until I stumbled on to the Kelly 50. I still lug around Kelly 18, Bach 12, and Bach 7 MP's.... but rely most on the Kelly 50. I use the others just to switch around and keep my chops 'awake'. I've thought about buying a REAL PT-50 but if the Kelly 50 would turn out to not be a reliable copy, I might be disappointed.

The Bach 12 is a good MP but I think I like the Kelly 18 better. I don't have a problem with plastic mouthpieces. They are really comfortable and I don't 'shudder' if I drop one! I honestly can't tell the difference between plastic and brass MP's.

Interesting. Thanks Dan.

I have read elsewhere that the Kelly 18 has a narrower rim than the Bach 18, and I do think the Bach 18 rim is too wide. But I have never had both mouthpieces together to check that claim. Several of my students have done very well with Kelly 18s, and I always recommend them to adult-size tubists.
How does the rim width of the Bach 12 compare?

Kelly used to have a blurb on their website that I cannot find now, that said something like they are physically patterned after the originals, but then tweaked to play like the metal originals rather than be an exact physical copy. What they are after is the sound/effect, not just physically molding the original, as I understand their approach. My point is I wouldn't expect the specs to match exactly.

I own three Kellys so far (18, H'berg, 25). They seem OK, maybe just a little less clear in articulation than regular mouthpieces, but who's gonna notice outside by the time the sound travels xx feet... Maybe it's just a perception thing on my part with the slightly deader resonance/feedback on the lips, maybe it's just my crappy chops, dunno. Still making up my mind on these things, but they are nice for sousaphone playing, not as much weight pulling down on the gooseneck and bits.

The Bach 12 has never done much for me, gimme an 18 or a 7, depending on the horn. I have one sitting in a shoebox I can sell you, it's in great shape.

Eric "who thinks the Bach 12 is seldom seen for a reason" L.

Art Hovey wrote:I have read elsewhere that the Kelly 18 has a narrower rim than the Bach 18, and I do think the Bach 18 rim is too wide. But I have never had both mouthpieces together to check that claim. Several of my students have done very well with Kelly 18s, and I always recommend them to adult-size tubists.
How does the rim width of the Bach 12 compare?

I don't have a brass Bach 18 here but the rim of the Kelly 18 is .284" wide and the Bach 12 is .296" wide. Not much difference.

Kelly measures down the side a tad more to get their advertised 1.285 cup diameter for their 18. The two I own, when you get just below the transition point of the rim to cup, measure exactly that with a good digital caliper.

Bach are notorious for making mouthpieces larger than "spec." For example, a recently manufactured "real" Bach 18 I used to own had the exact same rim as the Kelly and a 1.28 cup diameter, just a slightly shallower cup and a wider throat than the Kelly. It played harshly, and seemed to have something in the backbore profile that just made everything rough.

Yes, if you want the best 18 Bach never made, look at a Blessing 18: it has the slope away rim and 1.26 diameter cup with the appropriate cup geometry, throat and backbore as was arguably originally designed in the Mt Vernon era.

One more thing about a Kelly 18: wrapping the throat with a ring golfer's lead swingweight tape improves the dynamic stability of the mouthpiece significantly.

Off topic: Anyone have a link to info on the Kelly 50? I've never heard of it, and no mention of it on the Kelly site.

UncleBeer wrote:Off topic: Anyone have a link to info on the Kelly 50? I've never heard of it, and no mention of it on the Kelly site.

There was a 50 for sale on here a while ago, but Kelly has no information about it on their website. I assume it's just a newer product that you must call them up to order.

UncleBeer wrote:Off topic: Anyone have a link to info on the Kelly 50? I've never heard of it, and no mention of it on the Kelly site.

It is (was?) a copy of a PT-50. I do not know if is a regular production piece. If you search tubenet for "KT50", you'll get a few hits, one or two from Mr. Kelly himself.

I bought a Bach 12 a few months ago and FINALLY have had a chance to use it in a contrabass tuba (rotary Mirafone, I THINK it's a 187). Works fine for me, and I generally love my 18.

A Bach 18 is also one of my favorite mouthpieces, and I was toying with the idea of trying a 12, thinking that it might perhaps have all of the characteristic of an 18 that I like, while maybe adding a little more heft in the lower register due to it's larger inner diameter. Since my King is a relatively small bore tuba, I am thinking that a Bach 7 might be overkill for me. How would you compare playing a Bach 12 to a Bach 18?

The biggest difference is that the rim on the 12 is a little fatter and a little flatter than the 18. It plays entirely different than the 18. I like the 12, and I like Bloke's characterization of it as a good glove box mouthpiece. I think the Kelly 18 is like a Bach 12 rim applied to an 18 size.

SplatterTone wrote:The biggest difference is that the rim on the 12 is a little fatter and a little flatter than the 18.

Bob1062 wrote:The rim on my Bach 12 is noticeably thinner than the rim on my Bach 18.

Well, for crying out loud, which is it?

Is the rim on the 12 "fatter" or "thinner" that the rim of the 18?

UncleBeer wrote:Off topic: Anyone have a link to info on the Kelly 50? I've never heard of it, and no mention of it on the Kelly site.

As some posters have already mentioned... the KT-50 is/was a Lexan copy of the PT-50. A few of them were made off of a prototype mold and sold for $50 each.... quite a bit more money that the other Kelly mouthpieces. Apparently there wasn't much interest in the MP so a production injection tool was not built. I don't have a clue how many were actually made. I think Jim Kelly used to be a TubeNet sponsor. Maybe he'll chime in here. A friend of mine who owns an Internet music business gave me this one in return for some repair work I did for him a while back.

I use mine A LOT. It's a good MP for me. Of course... I thought the LAST MP I had before this one was the best, too!