Intalling K&K piezo pads

Got a new way of doing something? Or maybe an old method that needs some clarification.

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Trevor Gore
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Intalling K&K piezo pads

Post by Trevor Gore » Sun Jul 29, 2012 11:34 pm

I've come across a number of people who haven't been overly impressed with the factory instructions on how to install the K&K mini piezo pad pick-ups; the classical instructions call for drilling holes in the saddle slot, or measuring the distance from the soundhole using the lead and then taping it to get the placement right. The steel string method uses bits of card and golf tees. However, there always seems to be guitars with braces in the "wrong" place for drilling guidance holes, or the soundhole is too small (typically on classicals) to get your arm in and still be able to do the manoeuvring required. The guys who do a lot of these installations have no doubt come up with jigs and tools which work well for them, as have I. So here are some of the tricks I use.

The first is just a more robust version of the K&K golf tee method for steel string pinned bridges of the X-brace type. It uses a tool made from a piece of Perspex and a short piece of 3/16” rod (bits of off-cut from making truss rods).
Tool 1.jpg
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This method won't work for falcate braced guitars with the braces running between the bridge pin holes.

From the outside, chose where you want the piezo pad and select a bridge pin hole to use. Stick the rod into the bridge pin hole, align it over the position you want and mark the bottom of the Perspex with a Sharpie.
Insert in pin hole.jpg
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Remove the tool and stick the K&K pad onto the Perspex over the mark, using Blutak or similar.
Ready to go.jpg
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Apply the superglue gel, insert the tool into the correct pinhole from the inside of the guitar and pull it up to stick the piezo pad to the bridge plate. The trick: make sure the flat on the rod points to the position you want the pad in.

The second method I use is the “sheep pen” method. This method can be used on guitars with a variety of bracing types, provided you can get your hand in the soundhole and still have enough room to manoeuvre. I made these three “sheep pens” from 3mm thick PTFE (so any glue squeeze-out wouldn’t stick them to the inside of the guitar), but UHMW polyethylene will likely work just as well. On the underside is a piece of double sided tape.
Sheep pens.jpg
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The idea is to stick the sheep pens onto the underside of the soundboard so that they can be used to locate the K&K pads. The trick: you can move the pens around as often as you like and keep on sticking and checking (with a mirror) until you have them in exactly the place you want. And then it is quite simple to follow up with the K&K pad with its Superglue gel on the end of your gloved finger, locating it positively in the pen. If you land accidentally on the pen rather than in it, no worries, because nothing sticks to the PTFE.
In position.jpg
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The third method is one I use mainly on classical guitars with small soundholes (e.g. the one in the Rare Encounter" story) and I use this tool:
Swivel tool.jpg
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Swivel shoe.jpg
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It’s made from another piece of 3/16” rod (truss rod off-cut again) and the swivel shoe from the screw of a G-clamp. I added a wooden handle to make it easier to manipulate. The G-clamp screw has been drilled and tapped and the rod end threaded. A lock-nut holds it in whatever orientation is required for the job in hand. Bend the rod so that it clears any bracing and so you can get clear access to the target position.

The method: lay a mirror on the back of the guitar so that you can see the target position when looking through the soundhole. Stick the K&K pad to the swivel shoe using Blu-tak or similar, apply the Superglue gel and then, looking in the mirror, stick the pad onto the guitar.

I’m sure many of you have your own techniques. Please add them to the list!

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Allen
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Re: Intalling K&K piezo pads

Post by Allen » Mon Jul 30, 2012 5:47 am

Oh, that last one's a winner for me Trevor. Just try and get anything into the sound hole of a ukulele much larger than a few fingers....which never reach back to the bridge.
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Clancy
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Re: Intalling K&K piezo pads

Post by Clancy » Mon Jul 30, 2012 6:40 pm

Never done the K & K, but I've used these soundhole clamps to locate small patches to repair cracks.
Where ever the top of the brace is, the bottom of the brace will be inside the instrument.
Should work with the pickups as well.
http://www.stewmac.com/shop/Tools/Clamp ... lamps.html
Craig
I'm not the sharpest tool in my shed

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Kim
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Re: Intalling K&K piezo pads

Post by Kim » Sat Aug 04, 2012 8:00 pm

trevtheshed wrote: It’s made from another piece of 3/16” rod (truss rod off-cut again) and the swivel shoe from the screw of a G-clamp. I added a wooden handle to make it easier to manipulate. The G-clamp screw has been drilled and tapped and the rod end threaded. A lock-nut holds it in whatever orientation is required for the job in hand. Bend the rod so that it clears any bracing and so you can get clear access to the target position.
Clever bloody Trevor. :cl :cl :cl

Nice...Thanks for sharing with us mate. 8)

Cheers

Kim

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Taffy Evans
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Re: Intalling K&K piezo pads

Post by Taffy Evans » Fri Aug 17, 2012 9:03 pm

Hi Trevor thanks for that I'll be using some of those ideas.

I fitted a set to a steel string guitar recently and had an intermittent sound problem. If I moved the leads [from pickups to output socket] to certain positions the sound would cut out?? Are you aware of this problem? I have fitted many sets over the years and this is the first time it has happened to me.
Taff

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Trevor Gore
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Re: Intalling K&K piezo pads

Post by Trevor Gore » Sun Aug 26, 2012 7:18 pm

Sorry Taffy. I'm a bit late on to this one.

I haven't come across your specific problem, also having fitted numerous sets. However, there is a related phenomenon that occurs most of the time, but mostly it isn't a problem and it might help you sort things out. After I'd discovered how to fix the problem (momentary cut-out when tapping the soundboard as per Tommy Emmanuel(!)), I found this on the K&K website :roll:

I can't get a direct link up to this page on the K&K site, but here it is:

My Pure pickup seems to momentarily shut off, especially when I press or bump on the bridge with my wrist.

We've experienced this phenomenon a few times and it seems to happen only with the Standard size Pure but a very few incidents were reported with the Mini Pure as well. It has to do with two things: Extremely high impedance of the input you plug in (like LR Baggs Para Di or Fishman Platinum preamp or and very high impedanced acoustic amp) and a special protection circuit used in some amps .

First off, the pickup does not shut down momentarily, but the amp you are using has a safety protection circuit, which shuts the power amp down momentarily in order to protect the speakers. Some Fender acoustic amps and powered studio monitors feature this protection circuit.

What happens is this: A “burst” of low frequencies is produced when you push down or bump on the bridge with your wrist. This “burst” would actually cause very dramatic speaker movement and the protection circuit kicks in.

If you use Baggs Para DI preamp, for example, this may happen. It exaggerates the bass frequencies due to its extremely high impedance input. The Pure Pickup has strong bass to begin with and does not need any further boost. The remedy here is to use our K&K Pure Preamp and turn down the bass on the amp to the degree needed for good sound, but not more. You will also find that if you plug the guitar directly into a 1/4" line input of a mixing console, the “cut out” phenomenon will not happen. This is because the line input of the board is low impedance.


BTW, I experienced this on the Mini Pure. Dropping the input impedance fixes the problem. The K&Ks will work very well into impedances as low as 10k ohm (typical line level input impedance), but 470k ohm is probably as low as you'd normally want to go. As the input impedance is reduced, so is the bass response. I normally find this advantageous as I normally have too much bass (and always plenty of level).

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Taffy Evans
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Re: Intalling K&K piezo pads

Post by Taffy Evans » Mon Aug 27, 2012 6:21 am

Thanks for your trouble in sourcing this info for me. When I get the guitar back I'll check it out. I do remember at the time of installation and getting the signal back after losing it, and feeling happy with myself but not knowing really how I fixed it, I did the bang the bridge, top, sides and shake test and it still worked fine, until the customer gets it and it failed...kaput. I'll check my solder joints at the jack plug, there's no pre-amp fitted. Thanks again.
Taff

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