Externally vs Internally mounted Piezo?

[soliver]

Just curious about this:

My Silverangel has an internally mounted K&K, but I also own a JJB Marcato External mount piezo set that was formerly on my Eastman but I now use on my Jacobson. There is a noticeable difference in volume between the 2.

Is it a function of being internally mounted vs externally mounted?

Is it a function of them being of different manufacture?

My SA is typically a louder instrument acoustically, does it have more to do with that than other factors?

Or perhaps all 3?

I'm mostly just curious, but I do like the idea of using the Jacobson in "plugged-in" scenarios and would like to improve the volume produced by the electronics... thoughts?

Just for a frame of reference I use a Fire-eye Red-eye DI (good stuff!).

[pops1]

My guess is that the K&K is glued in and the top mounted JJB is either taped on or put on with putty. Both of which warm the sound over glue, but have less output.

[Br1ck]

Aren't K&Ks known for being a high output pickup?

[Markus]

I understood the JJB's were essentially copies of the K+K - seems like they're quite similar piezos, but I'm no piezo expert.

Being mounted on the top I am betting the difference in the mounting method affects the signal - I would expect to hear a difference if glued in vs. putty. When I installed my K+K's most of a decade ago I noted that different mounting locations yielded fairly diffferent results - enough so that when I'm getting my K+K's installed in my new mandolin I'm going to send it to someone who works with both pickup and that mandolin brand often.

[Steve Ostrander]

I have a Breedlove American FF that has an internal K&K mounted with the adhesive supplied by K&K. One of the discs let loose and I had it reattached with CA glue. I can tell the difference between the two. The CA disc is lightly louder and brighter.

[pops1]

I have two K&K pickups on two different mandolins, one glued in and one on top. The glued in one is louder for sure.

[SRNassif]

I tried the K&K pickup on my Collings MT2-O both with double-sided adhesive tape and glue. With the glue, the sound was much better, louder, and I had better control over it. I guess since the K&K picks up the vibration of the wood, the tighter the connection to the wood the better. As far as internal versus external placement, I am not sure what the exact physical explanation is, but internally mounted pickups sound better than external ones. It could be due that the internal ones pick up the sound vibrations at the surface directly facing the actual the sound box of the mandolin (i.e. the inside of the body), as opposed to the external pickups.

[pops1]

I think externally mounted pickups have a different relationship to the bridge, no top between the bridge and pickup. Instead of being under the top with the bridge on top, it is right along side the bridge if mounted on top. On the mandolin I have top mounted it is a different location than would be underneath. That mandolin is X braced and it did not sound good in the typical spot. I am also using thick double sided tape, it has less power and sounds warmer, but with the RedEye and K&K it still has plenty of power.

[illinoisfiddler]

I have found that a bridge mounted pickup is the best way to go in terms of volume and gain before feedback. Even Sam Bush uses an in bridge pickup. The K&K surface mount pickups can sound a little more like a microphone, but at the cost of volume and feedback. It depends on what you want, and what your band situation is like.

[soliver]

Thanks everyone for the replies. A few of you confirmed my suspicions that externally mounted Piezos are more frequently quieter than internally mounted. It's also interesting to learn how the glue vs tape methodology can make a significant difference, though it makes perfect sense! I may borrow an amp (I typically play through the church's sound system), and experiment with sticking the piezos inside the instrument, and if it's a significant difference, I may see if I can permanently mount internal piezos.

[Marty Jacobson]

A good place to put the piezo is right behind the transverse brace between the brace and the bridge, under either the treble or bass bridge foot. I did some testing on a braced oval-hole top and that's the one spot which has no important nodal lines (so it should be a fairly balanced representation of the sound). Of course, maybe you don't want a balanced representation of the sound.
Mounting it internally or externally should make no difference. The adhesive medium will definitely make a difference. The more rigid the adhesive, the better the transduction of high frequencies. Putty tape will work as a low-pass filter, or like rolling off the trebles on an electric guitar.

[soliver]

Thanks Marty, they were mounted with a very thin layer of blue tac.... maybe I'll try a different means of mounting them, or Its possible that the JJB just has a quieter output than the K&K ( particularly if internal vs external makes no difference).

[woodnstrings]

I had a K&K twin internal pick-up internal jack installed on my new Eastman MD815, installed by Elderly Music. The instrument sounds great unplugged or plugged in. Not sure what they used to glue it in.

[UsuallyPickin]

The only, IMO, reason not to mount a pickup on a mandolin inside the instrument is if it is collectible. An interior mount is out of the way of playing and storing your instrument. A jack at the end pin is also easier to deal with for me. R/