My project is a DIY talkbox using Monacor KU-516 compression driver.

I'm having a hard time finding the right connector to fit the hose to the driver, M35 is a rare size it seems.

There's one option of M35 x 1.5 looking through the tables for metric-thread sizes.

There's no information on TPI threads per inch on the datasheet for the driver. I read a tutorial from another builder, he 3D printed a part with 18TPI and didn't fit perfectly.

If anyone knows any item I could buy to solve without 3D printing a custom please let me know. (I've searched tap/hose adapters with no luck)

If I have to 3D print a part how should I measure the TPI accurately to make the correct thread?

I'm assuming the 18 TPI fitting didn't work as 25.4 (1 inch) / 18 = 1.41

If the flange is M35 x 1.5, at 18TPI would the fitting not snug enough?

  • $\begingroup$ The easy answer is buy a matching horn, e.g. Monacor SK 159. The driver then screws direct into the horn and the horn has its own mounting bracket. . studiospares.com/Headphones-and-Speakers/PA-Speakers/… $\endgroup$
    – alephzero
    Jul 1 '19 at 17:24
  • $\begingroup$ The "1.5" is the pitch in mm. 25.4/1.5 = 16.93 TPI, probably near enough 17 (but not 18). More details of the thread dimensions here: engineersedge.com/hardware/metric-external-thread-sizes2.htm $\endgroup$
    – alephzero
    Jul 1 '19 at 17:31
  • $\begingroup$ Thank you @Alephzero. To anyone that finds this and needs to solve the same problem, the horn driver comes with a plastic drinks bottle looking cap, this cap is only threaded half which could help when modelling from scratch. For the purpose of a talk box I just cut a hole in the cap to fit the PVC pipe and hot glued in place. 25.4 / 17 is a good shout, as gets 1.49 very close to the 1.5. Is there a way to confirm this now I have one and can measure it? $\endgroup$
    – Richop
    Jul 5 '19 at 10:16

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