special 20 mods

I was reading online about a guy who opens up the cover plates on his marine bands for more volume. Has anyone seen this done on a special 20? Does it increase volume?

I dunno…I did it on a cheap harp…and it didn’t help, but BB swears it worked for his MB!


I just got my new crossover and its wide open on the back . The cover is folded back leaving the opening twice as big as anything else I’ve seen. I’m going to try it on a special 20 just to see what happens. There must be something to it for Hohner to do it on thier newest model. What’s the worst that could happen?

It makes a difference. It definitely increased the volume. I don’t know if it changed the tone or not but I like it.


huh! Totally interesting!


Did you cut it out or fold it over?

I made little cuts at the supports. Following the angle up then folded back for strength. I used leather and pliers to fold it back. Going slow to keep from it from kinking for a smooth bend. This was my first time and I think I can do better next time.

You know, I’m an old trumpet man, trained as a brass specialist.
Different bell materials, sizes, and flares make real diffences we prefer for specific styles and venues. Opening up a bell can free the air column that carries the tone. Though harps have very much shorter air paths, decreasing restrictions to air flow will increase air flow at exit, reducing back pressure which makes the harp sing with less breath pressure at the mouthpiece. The tone is fuller with less effort, and I have more volume without overblowing and killing my harp. It just plays sweeter. I can really tell a difference between my modified MB and my stock LO. MB plays easier, freer, and louder. Of course it plays softly just as well.


I like the picture that Harpix posted and now all my sp20 are open end to end the same way. I also agree with BB about the sound and it does make it play sweeter. Now here’s another question. If different materials produce a different sound in trumpets, would different material for a cover plate make a difference in sound? Or would holding the harp the way we do dampen it to the point of not noticing a difference?

Well heavier or lighter material and heavy or light bracing makes a significant difference. Materials outside but also inside should make a difference even with hand contact.


Don’t cut them off. Take a pair of pliers, put some folded paper not to ding the covers, and carefully bend the back part of the covers in.

THe result looks much, much more tidy than cutting off the cover “sleeve”

Mine were only cut at the support post but since have all been bent back like Harpix’s. Nothing was ever cut away. I used a piece of leather and small pliers to bend it back. Very small steps at a time so as not to kink or ripple the cover to keep a good smooth finish. Now I do it to every harp I get except the crossover. They come that way.

Yes cutting the sleeve takes much more time.