K&K pickup installation problem(tape failure)

[Dave Richard]

I installed, for a customer, a K&K Mandolin Twin p/u in a very nice custom made 'A' style, with F holes.
Initial installation went fine(two layers of double stick tape, as in the instructions), p/u sounded good.
About three weeks after the initial installation, the treble side sensor dropped off the soundboard, the double sided tape having 'let go'. Some tape residue remained at the attachment point, most of it stayed on the sensor. The bass side stayed attached.
I carefully cleaned off all tape residue, and reinstalled the sensor.
Now, about a month later, same problem. One layer of tape remains on the sensor, the other is on the soundboard, but not intact: it's pulled off and somewhat 'smeared'.

What could be wrong?
There does not appear to be any finish or contaminent on the inside of the soundboard...Problem with the tape itself?...Inside curvature of the soundboard preventing good contact with the flat sensor?...
K&K tech have suggested applying two layers of tape to the sensor, then gel superglue it to the soundboard.
Has anyone else had this problem, and tried the tape & superglue method?
Thanks, Dave

[GarY Nava]

Sounds like a real pain! Whenever I'm going "stick" anything inside an instrument, I always try to seal the surface with a couple of coats of thin CA so that the pad or tape isn't going on to bare wood.
Cheers Gary

[Drew Streip]

I installed the K&K myself in an Eastman 515. Same problem -- treble side tape failure after a week. Tried again, same result.

I wanted to use a less permanent solution than superglue first. So I tried the same sticky tack that my fiddler uses, which lasted all of 10 minutes.

Then I went to a craft store and got some double-sided scrapbooking tape like this: http://www.michaels.com/recollection...html#start=120

I built up a layer of these to cover the whole transducer -- probably used 3 or 4 -- and placed it on the soundboard. It's now been about 6 weeks and 6 gigs, and it has held up just fine. Since the box contains 500 pieces, it should last me a lifetime if it ever fails.

The tape is a little less elegant than the K&K clear tape, but it's inside the mando, so who cares? Good luck!

[Steve Ostrander]

I had a K&K twin installed in my Breedlove last year and the adhesive tape failed at a gig after only a few weeks. I took it back to the luthier and he reinstalled it using CA. No problems since and I believe that the CA imparts better tone and volume.

[Max Girouard]

I've installed a couple dozen of these with no problems so far. Our procedure is to always apply two layers of the double stick tape, blow out the instrument with compressed air and to also clean the mating surface with alcohol. Sometimes buffing compound or fine sanding dust can get in there interfering with the adhesion of the tape.

[fox]

I read a tip a few ago about using the little double sided spots you can buy in most stores, they have a very thin layer of foam in the middle. I had been assured that these little spots would in fact increase the pick ups performance & remain stuck for a long time!
I don't really know about the improved sound but, they have stuck well and the pick ups sound great.

[AcornHouse]

I use medium-thick CA. The more solid the connection between the piezo and the soundboard, the stronger the sound, I believe.

[pops1]

When I mount these inside I use two pieces of tape super glued together glue the tape to the pickup and the other side to the mandolin. I feel the tape makes a warmer sound, but needs to be glued. It is still very hot, but warmer than gluing the pickup straight to the mandolin. They can still be taken out if need be, I have done that several times without damaging the pickup, but it is a pain.

[Mandobart]

I use JJB pu's (very similar to K&K) and have installed them in 15 instruments over the past 5 years or so. I attach them using loctite hobby putty. Holds well, does not damage or discolor the wood or pu heads, removable, cheap.

[Drew Streip]

I installed the K&K myself in an Eastman 515. Same problem -- treble side tape failure after a week. Tried again, same result.

I wanted to use a less permanent solution than superglue first. So I tried the same sticky tack that my fiddler uses, which lasted all of 10 minutes.

Then I went to a craft store and got some double-sided scrapbooking tape like this: http://www.michaels.com/recollection...html#start=120

I built up a layer of these to cover the whole transducer -- probably used 3 or 4 -- and placed it on the soundboard. It's now been about 6 weeks and 6 gigs, and it has held up just fine. Since the box contains 500 pieces, it should last me a lifetime if it ever fails.

The tape is a little less elegant than the K&K clear tape, but it's inside the mando, so who cares? Good luck!

Spoke too soon.... I played my mando last night and heard a slight rattle. Turns on the tape failed. On to the next solution, I suppose.

[Don Grieser]

I think it's a humidity problem. Out here in the dry Southwest, I've never had the tape fail. Had them in for years.

[Atlanta Mando Mike]

Atlanta has a lot of humidity. Ive had K&K's in 6 or so mandolins over the last 3-4 years and have never had a tape failure.

[Dave Richard]

Thanks for all your replies.

I've reinstalled the sensor, with two layers of tape, then superglue to the top. But it's much hotter than before, and I'm not sure the tone will be acceptable to the owner. Hmmmmm....of, course, now it won't fall out....

[Dale Ludewig]

On a recent installation of the K&K on one of my own mandolins (that I built and kept to play), I found the K&K's too hot also. I bought their Trinity (I think that's the name) Preamp. Then run the output from the mandolin through the XLR route on the preamp. Problem solved.

[lenf12]

Yeah, I've not had good luck with the double sided tape either. I used with a K & K and it was way too hot going direct to an amp. I haven't tried CA but hear good things here on the Café. I have used and really like the Blu-Tak putty available at office supply stores. A little dab'll do ya and I believe it attenuates the pickup's response, in a good way.

Len B.
Clearwater, FL

[Folkmusician.com]

I glue K&K pickups in unless the customer specifically requests otherwise. I believe CA is the best route.

[Steve Sorensen]

I've had trouble with the tape approach too . . . even with careful cleaning . . . on installs with the added convenience of going on before closing the box.

Dot of thick CA.

Steve

[amowry]

I've always used medium or thick CA (like K and K sends with the pickups) with no problems. I think you could pop it off later if you really wanted to. It helps to scuff the metal surface with fine sandpaper first.

[pops1]

I don't think K&K is sending the CA anymore. At least in the last couple orders I got.

[Folkmusician.com]

I don't think K&K is sending the CA anymore. At least in the last couple orders I got.

Yeah, no CA in those that I receive either.

[Dave Richard]

As noted above, I did reinstall the sensor, with two layers of tape, and superglue. While I thought the sound was too hot, the owner used it at a gig last weekend, and reported that it sounded fine. Whew!

[pops1]

They are very hot if straight into an amp, but that's not how they are supposed to be used, a preamp or an amp with a highZ input is best and tames it down. I like the two layers of tape instead of gluing straight to the mandolin, I think it is warmer.

[McIrish]

I have installed K&K pickups in 7 instruments so far. I always use CA gel. If you are careful, it can be removed later if needed. I couldn't see running the risk of a pickup falling off the soundboard in a show. I travel a fair amount and changes in weather could make the tape have even more problems. Just my two cents...

[bernabe]

Something else to think about using the tape...its hard to install and avoid the lead wire from lying vertically over the tone bars if they're "parallel" or semi parallel [i.e not transverse or x-braced]. The height of TB's vary from maker to maker and the wire is a bit stiff where it joins the PU adding a slight upward prying type pressure, especially at the bass side as its usually closer to the aperature. i.e it also may never have seated completely flat in the first place due to the TB. This may explain varying results of the effectiveness of the tape from person to person. You may want to try to have the wire run as parallel to the bar as possible and try to seat it firmly with your finger or pincky- without cracking the top of course.

[Mandobart]

....try to seat it firmly with your finger or pincky- without cracking the top of course.

I use an S-type sound post setter to seat the pu heads against the underside of the soundboard. I use low tack blue painter's masking tape (or the green "frog tape") to protect the finish around the f holes.