Exactly what the title says, what of your playing improves from using these?

Maybe the strength in your let arm. Playing doesn't improve so much with hardware. If improves with you and the practice you do.

I don't think they improve your playing, but do darken the sound. Then again...I have never used them...

Sorry to add more information from someone who doesn't use them--

my recollection is that the idea is to change how the horn vibrates while you play. Horn vibrations remove energy that could be in the sound. You add the weights, and that changes the frequencies that the valve cluster will vibrate at (presumably to lower frequencies).

I've heard people say the weights help slotting.

Sorry, the idea never made a lot of sense to me, so I am not that versed on it.

i added a heavy third valve cap to my old shilke x3 and it seemed to make it slot a bit more securely... which was surprising as i expected it to do nothing whatsoever.

-Adrian

My Harrelson has medium weight upper and lower valve caps - I specified them based on advice provided by Jason Harrelson. Jason said that the notes slot better than with standard valve caps.

The trumpet is very precise and the notes form just as I think they will, and with very little effort - I don't have a set of standard caps to interchange so I don't know if it is my ever developing skill, the high quality build of the trumpet, or the caps, but these medium weight ones work a treat and I'm not changing a thing.

None of my other trumpets slot as well, but they don't have weighted caps, are not spec built by hand, and are not Harrelson trumpets.

So, once again, they are your beer vouchers, spend how you will.

I use heavy caps and they seem to help with the slotting

If you choose to use them, take careful note of how the instrument sits inside the case with the caps installed. I am speaking specifically of the longer caps that add length (about .5") to the bottom of the valves. With many of the single cases, the trumpet simply will not fit into the pre-formed area. With the multiple-horn cases and gig bags, it usually will....however...

I discovered that the top of the case partially depressed the valves when the lid was closed. Not only does this place unnecessary strain on the valve springs, but any shifting/settling of the horn during transit could cause unnatural valve moment that damages the valve surface.

As for the added weight of the valve caps to the sound dynamics of the horn, I found the difference to be marginal and of little effect regarding slotting. What I did like was having a larger valve cluster to hold on to.

The purported advantage is improved slotting. The additional mass supposedly minimizes unnecessary harmonic frequencies assisting with the notes being easier to produce. i read somewhere (probably here) that one can achieve similar results by adding a dime in the existing valve bottom covers. i tried it with my old Courtois and it indeed seemed to make a difference in the ease of centering each note. I of course checked to make sure that it didn't interfere with the valve stroke. for thirty cents its a cheap way to see if you like the change or if it makes any difference for you.

Ed Fitzgerald

Courtois L bore trumpet
Olds Super w/ Bach bell (uptilt) Frankenhorn
Rydy Muck Blessing Super Artist clone (.458/.468 bore)
Getzen Eterna 4 valve flugel
Olds Special cornet
Besson cornet

What do you get from heavy valve caps?

a horn that doesn't fit in most cases