JDR Trochilus: A Look inside and its potential as a customizing platform

[Brendan]

What's the hole spacing on the Trochilus, Dom? I mean between mouth or slider holes.

On most chromatics it's roughly 9.35mm, but on the Easttop 1040 it's 9.65mm.

Incidentally, it's quite easy to swap around welded reeds. I did a YouTube video on it about 15 years ago, and there have been others since:

https://youtu.be/kChMKU7LEVo?si=zjubQybFd0TYkC2V
https://youtu.be/ZAiMsUXQpLc?si=1wTkJIe4cl_n6Ogr
https://youtu.be/7FWEvUhLU2U?si=IKqseir1zEeNaxS0

[dominico]

What's the hole spacing on the Trochilus

9.65 for the Trochilus as well.

[Brendan]

Thanks! That could be useful.

I've ordered one myself, so I won't need to keep asking about small details

[dominico]

A "switch harp / double chromatic" for these might be a lot of fun.

What's better than two bendable diatonic harps stacked on top of one another? Four bendable diatonic harps stacked on top of one another!

[Brendan]

It is indeed a great concept Dom! You might be interested to check out this 2015 video, showing a bunch of cool possibilities for quad-reedplate twin-comb harmonicas. The bendy version is at the end:

https://youtu.be/sJGBnZXRHWg?si=AgLbWN8xwTsPAMsa

I tend to think of these collectively as Double Chromatics, but perhaps a better generic term to cover the multitude of tuning options would be 'Twin Slide-Harmonicas'. Whatever you call them, they're tough to make! (That is, with the same pleasing response and tone as standard diatonic or chromatic harps). Several difficult issues have to be overcome:

There can be a problem with Helmholtz Resonance Coupling, because of the longer air chambers. This occurs when the resonant frequency of the combined oral tract and comb/mouthpiece chamber is lower than the pitch of the reed. Then the two fight each other, with the result that the pitch of high reeds can flatten dramatically. In extreme cases, they can even stop playing altogether!

HRC was a problem with the bulky harps I showed in the video. It can be solved with a much more compact design where the reeds are close to the mouth, and the slimmer comb of the Trochilus will help with that.

Another big problem is airtightness, because you need two sliders. However one does it (two front slides, one front slide plus reedplate sliders, or whatever), that's two sources of potential air loss. Slide tolerances have to be super close.

To mitigate air loss, the easiest setup is with two fully valved chromatics. The option you want, un-valved or half-valved for interactive reed bending, is considerably harder.

However, I showed proof of concept of that in the video - so don't be dissuaded! With your good engineering skills, hopefully you can come up with a super-airtight, compact assembly for a double chromatic type of harmonica that plays as well as a single Trochilus.

If so, that will be something impressive. Good luck!

[Brendan]

Here are a couple of clips using customised Trochilus models as X-Harp prototypes, playing iconic guitar solos:

FREEBIRD - Lynard Skynard
https://www.instagram.com/reel/DCm15zbu ... R1YnJpNGh0

COMFORTABLY NUMB - Pink Floyd
https://www.instagram.com/reel/DB2Ug--J ... J2cDlvcGZj

I find learning guitar solos is not only challenging and fun, but it also tells me what my latest prototypes can do and what's still beyond them. That spurs on further developments

[dominico]

These sound great!

I especially like the "Stairway to heaven " one you just did.

I had started learning a couple solos on my retuned Trochilus tuning before I went and messed up my rib and threw my projects on hold for yhe time being. I had found, as you predicted, a couple things I want to tweak.
I still have a love-hate relationship with the slide, but if I can find a way to either rework it or protect it when it's in my pocket maybe I'll learn to live with it.

[triona]

And I can not open those Instagram links.

[Brendan]

Triona: all my short Instagram and TikTok clips are up on my YouTube channel as well:

https://youtube.com/@brendanpowermusic? ... 6HWkCKfrY8

[Brendan]

Domenic: sorry to hear about injuring your rib - I hope it's healed now.

Here's a new clip on the same X-Harp prototype #7 using the Trochilus as base platform: the iconic guitar solo from the Eagles' "Hotel California" (actually just the first half of it):

https://www.instagram.com/reel/DDlDXkwo ... A5cGlxbQ==