Modifications to Conn 73H

[Mertelstein]

Those who've seen other posts by me know I have a late 70s (I think) 73H. Dating has been impossible as the markings have worn away and been lacquered over, so I'm going by the modern script on the bell, and the fact that the bell engraving is on the underside (i.e. facing the ground when you're playing), which match that of another player on the forum who has a 71H.

I also have a '76 Duo Gravis, which is my preferred horn. However, I've been playing more in amateur orchestras lately, and the 73H definitely blends better there. I also hugely prefer the slide.

The one thing that has always frustrated me with the 73H is the common problem with resistance in the valves. They are both much more tight compared to the DG; however, while the F trigger is fine with no discernible difference to the Fs on my tenors (both 88Hs), the D trigger is borderline unusable - it's so stuffy and feels like I'm blowing into a brick wall. I've stripped the valve down, checked the alignment etc, and there's nothing mechanically wrong that I can see. I also know that this era of Conn basses are notorious for their stuffy triggers.

My questions to the forum are the following:
- would a different wrap for the D extension work? I have a custom made one which mirrors the DG (i.e. long and straight) but I have seen some 73Hs with a "wider" D wrap - would this affect the resistance?
- if the answer to the above is as I expect ("i.e. not so much") is it worth considering having the valves replaced? And if so what is the best route - find some rotary valves that would swap over while maintaining the existing wraps, or go for a complete rebuild of the valve section?
- or do I just sell this and try and try and find a more modern second hand orchestral bass (given I live in Europe and money's a bit tight - this might be a fantasy...)

Thanks in advance!

[Crazy4Tbone86]

You state that you have checked the valves for alignment. When must people do that, they only look at the witness marks on the spindles and bearing plates. This can be problematic because there are many rotors that have poorly placed witness marks. I have seen rotors where the witness marks were off by as much as 30-40 degrees.

A better way to check the valve alignment is to view the ports on both sides. This might take a scope or other tool, but it would give you a better read on the alignment of those valves.

[Mertelstein]

Thanks - I suspect it will definitely need a scope to check full alignment. Obviously when re-assembling, you do a cursory "eye-check" but that's very far from accurate (although enough to avoid a 30 / 40 degree misalignment).

All that said however, I wouldn't necessarily say it feels or sounds like something is obstructing the air flow - with effort the notes resonate as well as on the F trigger (obviously not as well as open). I imagine if the valve was not fully aligned, the resonance would be less? My own view however is that the resistance to the airflow is sufficient of an impediment to consciously avoid using both valves.

Of course, the fact that the vast majority of repertoire I'm playing is late 19th / early 20th Century and therefore you can count the times the parts dip below a low E natural on the fingers of one hand mean this isn't a major problem. For big band work that more routinely goes lower, I've got the (very free flowing) DG. The challenge really comes in small ensemble (quartet / quintet) work - but again, only on the rare occasions I'm required to play a low B natural (both horns are dependent, and I've never played an independent so happily don't know what I'm missing)!

[chromebone]

The 73H has average sized bass trombone valves for the era, which would be on the smallish side now, but it does have larger tubing through the valves than the bore of the instrument, which is what most bass trombones have.
The DG, on the other hand, has large valves for the era, more like average valves for bass trombones made now, but the tubing through the valve is the same bore as the rest of the horn, which is unique to Kings.
What you may be experiencing is the difference in blow between the two setups. The DG is easier to play through the valves, although the sound is more direct than a modern bass trombone. Compared to the 73h, you may be perceiving the 73h as being “stuffy”. Most likely it’s that you need to adjust your air to accommodate the larger tubing through the valves.

[Mertelstein]

Thanks Chromebone - this is really interesting. I’d known vaguely about the through-valve bore but this is a very clear explanation which helps me understand it much better. This is almost certainly my ignorance shining through however, but wouldn't what you suggest imply that the problem is insufficient air flow, and therefore the sound is anaemic? That would not be my problem in this case - it's more the resistance / push back when putting air into both valves. It feels, from a playing point of view, almost as if the opposite is true to what you say - that the bore on the second valve is tighter than regular (I hold my hands up and admit this is almost certainly me misunderstanding your point, so no offence meant here).

I also have absolutely no doubt some of this is technique-related as I’ve only just returned to playing bass. I’ve spent much of the past 10 years playing tenor on an 88H. I think this is why I am quite comfortable on the 73H F-plug.

I definitely feel that I need an adjustment to get the sound through both valves to be “good” and with effort it does. Again I’m certain the effort will decrease as I reacquaint myself with bass trombone and get more in shape. But I do feel the differential between just the F-plug (fine) and both plugs (like playing through cotton wool) is a bit beyond what I would consider “normal”. It's a completely different feeling through the second valve than just the first. I need to do the scope test as suggested by Crazy4Tbone and see if that explains it first.

[chromebone]

I’d recommend having a good tech check the valves first and make sure there’s no leakage or something that is obstructing the air flow. I’ve never seen a 73h with replacement valves, they usually work pretty well as designed.
Does the engraving say Made in USA , Elkhart or Artist Symphony? If it doesn’t say Elkhart, then it’s an Abilene made horn, some of those suffer from less than optimal assembly. A good tech could take it apart and reassemble it which can help playability.

[Mertelstein]

Thanks chromebone. Definitely an Abilene horn - it’s an Artist Symphony (theory on the rest of the forum was it was a “Friday afternoon” job…!). Not desirable by any means but with the exception of this valve issue I like it!

That’s a good suggestion - better than my amateur poking around. I have to go to Atelier Pfeiffer in The Hague anyway with my 88H, so I can throw in the 73H too! Thanks for your help.

[hyperbolica]

The issue of "stuffiness" with trombones is often just perception. When a horn feels stuffy to me, I check out a couple of things:

- Is the air flow plugged up or leaking? Something stuck in the horn, a valve half shut, a water key open, an open joint...
- Is it vibrating properly? There might be something damping vibrations like a bad solder joint.
- Is it just a question of resistance? Resistance is not always a bad thing.
- Sometimes small horns seem stuffy because you're trying to blow too much air through them. This is probably not the case with a 73h. But backing off the air can sometimes make the horn feel less stuffy.

[chromebone]

I own a King bass trombone and a Yamaha bass trombone. I love both of them, but I do have to adjust my air concept when switching between the two, especially when playing through the valves.

[Mertelstein]

Just thought I'd put a "fine" on this post, mainly because it shows what an awesome community we have here.

I spoke to imsevimse (AKA Tomas from Sweden) who I knew owned a 73H to see his feeling on it. One thing I hadn't tried that he suggested was a "pop" test when removing the D slide. In short - there was no "pop" of the air seal when removing the slide, indicating there was a leak somewhere. However, when using the "stubby" E slide that was originally on the trombone, the "pop" was there. This always repeated itself whenever I tried it, which led me to believe I had a "duff" D slide. On Tomas' recommendation I had Lars Gerdt make me a "Stauffer" D slide for the second valve. I've had it for a few days now and the difference is remarkable - there is more of a consistency of feeling, of playing and fundamentally of tone when using the D trigger. Notes blend in a way they did not feel like they did on the previous slide (as an aside even the two weeks I spent playing with just the E were a big improvement).

I am still going to get the horn cleaned and inspected (and while I'm at it have the triggers split), but this has already been such a massive improvement. What a superb community we have.

[ithinknot]

Glad you got it sorted.

There could be a leaking joint in your previous D slide, or it may have been assembled with undersized legs that'll never seal properly. Conn wrap tube has much thicker walls than most others, so this is quite possible. There's plenty of tube out there with an essentially appropriate ID around .594, but the Conn receiver tubing is expecting an inner OD at or just under .640, whereas other manufacturers might be as small as .625 OD for the same inner bore.

It's worth having that checked when you bring the horn in for service, because if it's a simple leak in that slide, you might as well have it resoldered and you can sell the part on to someone else... but not if it's an intrinsic fitting flaw.