Sunday, June 19, 2016

Fitting the Headway transducer

In the last post, I mentioned that Rob’s Standard mandolin was not quite standard.  Rob has a couple of custom requirements; one of my handmade tailpieces and a Headway transducer.
One issue with using an under saddle transducer on a mandolin is housing the battery. Fitting a battery through the sound hole is a tight squeeze and all of the strings have to be taken off, which in turn means the bridge moves. The Headway solves this issue by using an external prep-amp which can also be used as a phantom power source for the transducer thus eliminating the need for an internal battery. With a stereo lead, one channel is used as the transducer’s output and the other as its power supply. The preamp itself is quite a neat thing and can go on a belt clip, if you wish.
 Here’s the completed tailpiece……………
…………….the large 12mm diameter hole is for the jack socket endpin.
 So, the soundboard is glued to the rim, the excess spruce trimmed and the position of the tailpiece carefully marked out, checked umpteen times, and the pilot holes for the tailpiece's screws drilled.
The tailpiece is screwed in place and a 12mm hole is drilled through the rim and tail-block. 
The transducer can then be test fitted. You can see why it’s a very good idea to use plywood for the tail-block, anything else and you run the risk of the block splitting. 
With the various nuts and washers adjusted for a perfect fit, the transducer is removed. Next, I like to glue the backing nut in place with CA; this helps with the final fitting once the mandolin is complete and you’re working blind through the soundhole.
 And after one last clean-up, the back is glued on to form the magic box.



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