This post comes from Mike Shirley via TromboneChat.
I recently had the pleasure of working with Colter Weatherholtz, the founder of TromboneLAB, and I wanted to share my initial thoughts on the result – a fantastic, custom carbon fiber slide for large bore (.547) tenor. In chatting with Colter before embarking on the project, his approach to design and use of materials really resonated with me. The finished product exceeded all of my expectations. More specifics (and pics) to follow, but first, a brief detour into carbon generally…
If you’ve run across some of my posts in the past, it probably won’t come as any surprise when I say that I’ve been rather enthusiastic about carbon and its use as a material in trombone construction. There’s a lot to love about carbon as a material – not least of which is its fantastic specific strength (also known as strength-to-weight ratio). Comparing the specific strengths for various metals to carbon tells a compelling story:
| Material | Density (g/cm³) | Specific Strength (kN*m/kg) |
|---|---|---|
| Copper | 8.92 | 24.7 |
| Brass | 8.55 | 67.8 |
| Stainless Steel (304) | 8.00 | 63.1 |
| Titanium | 4.51 | 76 |
| Carbon-epoxy composite | 1.58 | 785 |
Some of the different carbon fiber composites have an even higher specific strength, but even using the low end represented in this table, there’s an order of magnitude difference comparing to many common metals. If specific strength were the only factor to consider, the adoption of the material in instrument making might be much higher. But, strength is just one factor among many to weigh. What about cost, feel, weight & balance, sound, response, aesthetics, and all of the other factors by which we judge our instruments? Well, to be honest, after spending a few years really wanting to love carbon, I have to say that it does better in some of these areas than others. How carbon fares in this use case depends partly on the intrinsic nature of the material, but in my experience, equally important (if not more so) is the approach taken in design and implementation. Optimize for weight savings? Sure, that can and has been done – but once the novelty of holding a feather weight air-trombone wears off, we’re left to grapple with the increased amount of effort required to project the same amount of sound on those compared to instruments made of more traditional materials.
Having owned 4 carbon slides of differing bore sizes (.508, .525, .547, and .562/.578) over the last few years, I came into my initial conversation with Colter knowing what I wanted to avoid in a new project – I was not at all interested in the “wow” factor of carbon for its light weight, but very interested in reducing the sonic inefficiencies that a weight-focused design approach seemed to produce. Before I even raised this point, Colter was already ahead of me – the approach he articulated was focused exactly where I wanted it – the sound. The other concern I had was that comparing my other carbon slides to my metal slides from Edwards, Shires, and other makers was very difficult – the widths were different, the crook radii weren’t the same, etc. – many differences apart from just the materials used. Here again, Colter beat me to the punch – he offered two options to reduce these differences: he could build a custom outer slide to fit an existing inner, or he could fabricate a complete slide using OEM parts I preferred. I chose the latter option, and sent over the order info from my TW47NLW Shires slide. Colter sourced the necessary parts from Shires, including not just the inner slide pieces, but also a factory crook to use for the outer. I was convinced in planning this build with him that this would be a carbon option as close to my factory Shires slide as I could get – if I still felt that the result fell significantly short, then I was ready to write carbon off as a novel, but ultimately suboptimal option. However, my faith was restored from the first note 
Aesthetics are very subjective, and for many, an almost entirely dismissed aspect of our instruments. Personally, while I’d still rate function over form, I do appreciate a finely crafted piece of equipment. A beautiful instrument is enticing, sitting on its stand – it beckons me to pick it up and play it, and using a well-made thing is a joy in itself. But, what is beauty? In the eye of the beholder, to be sure. A New York era Bach or an Elkhart era Conn (or one of the many other fine makes from shops large and small around the world), replete with the many and varied battle scars incurred over decades of loving use is no doubt a beautiful thing to behold for many, myself included. But, no less beautiful (to my eye) is a shiny, newly-crafted work of art from one of our modern masters, whether Steve Shires, or Matthew Walker, or Matthias Hölle, or Miles O’Malley, or (the list goes on)… gazing upon these fine instruments is to travel through time – to imagine the many decades of beautiful music they will produce, as have their worn (yet no less beautiful for that wear) forebears. In the list of designs and materials one pictures when daydreaming the ideal trombone, carbon may be in a different place for everyone – higher for some, much lower for others. For me, the aesthetics of carbon can be very beautiful when incorporated thoughtfully into an overall design. I really enjoy Colter’s approach in this area – not just with the carbon, but in so many of the design elements, and how they blend together to form the whole.
I suppose I can’t very well expound on aesthetics without offering some pictures. I’m having a tough time getting pics to upload with the state of the forum, so I’m going to try external hosting and links from imgbb. But, I’ve uploaded a set of pictures to Google Drive in case I can’t get many working here: https://drive.google.com/drive/folders/ … MbBPTLWLeF. So, then – here’s a view from the lower end of the slide, where a lot of very interesting stuff is happening:
I’ll start with the crook guard, which is obviously hand-hammered. Personally, I think that’s a really nice visual touch, but it actually has a purpose beyond aesthetics – hammering the brass work hardens it, making it stiffer and better at protecting the crook. Note also how the crook guard extends for the full length of the crook, whereas the guard on many factory slides is quite small in comparison – almost to the point of being strictly decorative. Protection of the crook is an important consideration for carbon slides. With metal outers, if your crook is damaged beyond repair, a good tech can remove and replace it with a bit of torch work. The story with carbon is somewhat different – torch heat and carbon is a combination you want to avoid. The same crook swap you might have done on a metal slide would be quite problematic on a carbon slide. This is just one example of how Colter has carefully considered the design elements, and blended both form and function very well.
The ferrules joining the outer tubes and the crook are very substantial looking. To my eye, in combination with the design of the end pin and some of the elements in the upper portion of the slide, the design evokes an Art Deco vibe, which I find quite interesting and different from any other make I’ve seen. These beefy ferrules provide an excellent base for attaching the lower slide brace (a similar concept to the removable Sauer-style braces, but permanently attached) – a custom option that Colter made for this project. The Saturn water key ties together the other black (carbon) and gold (brass) elements of the slide visually, and keeps the lines nice and clean looking. Also, I’ve just really come to prefer that water key (I have long-ish arms, so reaching them isn’t an issue) – I have them on all of my slides now.
Altogether, the lower section of the outer slide is certainly beautiful to my eyes, but also highly functional. With a fully closed slide (1st position), the sound path is all metal, exiting the metal inner top tube, entering the metal crook, and re-entering the metal inner lower tube. Progressively more of the carbon outer slide is exposed in longer positions, but the sonic differences are very small between 1st and 7th on this slide – almost to the point where I’d say the difference is negligible or within the margin of error if I were to compare two different slides of completely metal construction. I can’t over-state the difference that a metal crook (also the mass in the complete lower section) makes compared to a lighter carbon crook – the sonic differences are huge to my ears, and the feel and response are even closer to my factory Shires slide than I had hoped. The focus and slotting that the lower brace provides blew me away. I actually think that this slide slots and projects better than my TW47NLW, which I wouldn’t have thought possible of a carbon outer before this.
Moving up to the other end of the slide:
I really dig the asymmetrical brace design for the right hand. The fittings are again substantial and carry the Art Deco vibe from the lower ferrules, and the grip area is quite comfortable. I also love the use of metal oversleeves here – not just for the added mass and associated stability, but also because they provide solid attachment points for the metal brace. I haven’t really been a fan of carbon braces on my other slides – this one feels familiar. Here’s another view, including the tube ends:
Finally, here is a view of the outer slide together with the Shires left hand grip assembly:
So, how does it feel? Unlike my other carbon slides, this feels very similar to a metal outer. I was shocked at how similar, actually. I had adapted to that “air trombone” feeling you get when playing super light all-carbon outers. This slide has the familiar inertia of a metal outer. In fact, it felt so similar that I decided to weigh the outer from my TW47NLW and compare. To my amazement, they both report precisely the same weights on my scale – 8.8 ounces. Why is that shocking? Never once in my conversations with Colter did we discuss a target weight for the build. He incorporated my custom requests, like the lower slide brace and Saturn water key, and everything just magically landed at the exact same weight as my metal outer. BUT – my metal outer lacks the heavier braces, oversleeves, and other custom fittings, so despite having metal outer tubes, it feels (and sounds) less focused than the TromboneLAB build. Really great stuff – same weight, but better player feedback and sonic results. I’ll also say that alignment was dead-on, out of the box – and while I’ve only had it in my hands for a few days, there hasn’t been any of the slow, sticky feeling that my other carbon tubes seemed to wind up with. Yama-snot works great for this slide – no special care and feeding required.
To say that I’m extremely pleased with the outcome would be understating things. I know carbon isn’t everyone’s bag, but if you are curious or actively in the market for a carbon slide – TromboneLAB is the one you want. It will spoil you for other slides. On top of all of that, Colter’s customer service and communication is excellent – he’s just a joy to work with.
That was a lot of text – if you made it this far, I hope you enjoyed the post, and give TromboneLAB a call!
Mike Shirley