Mandolin Pickup Install - Luthier Tips du Jour Mailbag
In this episode, Robbie O’Brien shows how to install a K&K pickup in a mandolin.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: What pickup do you recommend to get more volume from my mandolin and how do you install it?
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from Arkansas.
"Dear Robert, I need more volume from my mandolin and want to install a pickup. Which pickup do you recommend and how do you install it? Thank you for all your videos. Mark in Arkansas."
Mark, there are a lot of different types of pickups you can use to amplify your mandolin. This morning I had a client drop off a mandolin and ask me to install a K&K pickup in it. So, I'll show you how to install that if you like. The installation process for other types of pickups are very similar to this one, so let's get started.
Remove the tailpiece and the strings
So, Mark, I'm going to have to remove the tailpiece, which means the strings have to come off, which means the bridge has to come off. So, it's a good idea to come in with some tape and mark that bridge location so you can place it back in exactly the same location that it is now. Notice how I put a little dog ear on the tape? That way I don't have to pick at the finish and risk damaging it when it's time to remove the tape. I can now release the tension on the strings, and then just remove the strings from the tailpiece and slide them through.
With the strings off, I'm now able to remove the screws from the tailpiece and remove the tailpiece. Make sure you keep your screws and all the pieces in a safe place, because it's a real bummer if you lose one during the installation. The manufacturer recommends that I drill a 12 millimeter hole. Since I can't drill a 12 millimeter hole cleanly because it's already got a hole there in the end block, I'm going to use a step bit. I got this at my local Luthiery supply warehouse, also known as the local hardware store. It's going to step all the way up to a half inch. Now, that's a little bit bigger than the 12 millimeters recommended by the manufacturer, but it still works [Robert drills a hole in the end block using the step bit]. And it is normal for the pucker factor to go up a little bit during this operation.
Install the endpin
The next step is to insert the endpin jack into the F-hole and fish it out through the end here. Now, this may take a little bit of trial and error, because you want to adjust the screw here so you have exactly the right amount exposed here so that when you thread on the strap button, you have exactly the right amount exposed. Now, what you can do, is take something like a dental pick and just slide it into the hole there, and that will give you a quick measurement of how much you need. You can then place that onto your end jack here, and that looks fairly close. Let's try fishing it through there and then we'll do a little trial and error to make sure it's right.
An old guitar string works really well for this next step. Just slide it through the end block, and then fish it out through the F-hole, like so. Then come in and place the string through the hole here in the jack, and just wrap it around like that. You can now fish it through. And with any luck at all, comes right out through the end hole. So now, you can very carefully place the washer and the nut on there to make sure that you've got the right amount exposed out the end of the block there. It's important that when you place your strap button over that, that the threaded part of the endpin jack is recessed ever so slightly in there. And to me it looks like I need to adjust mine out about another 0.125" of an inch. So, I'll go ahead and do that.
Install the transducers
So, very carefully fish the pickup back out through the F-hole, and then adjust this part back here [Robert twists the top of the endpin jack to adjust it], in my case, about an 0.125" of an inch. Once the endpin's ready to go, I then used my old guitar string again to fish one of the wires over to the other side here. The other transducer I'm just going to fish out with a pair of tweezers over here on this side. Next, I place a piece of double-sided tape, that comes with the product, onto the transducer. I'm going to do that on both of the transducers. And the manufacturer recommends that you put two pieces of double-sided tape. I'm now going to remove the paper backing and then apply one more piece to the top of this. So, once you get the tape off, go ahead and place another piece right over the top of that one. And you want to do that on both sides.
Notice how I'm taping the transducer to this outside of the F-hole there so it won't fall back inside there. Next, I use a pair of scissors to trim the double-sided tape right up next to the transducer. Obviously, you want to be very careful not to cut the wire going to the transducer. Technical term for that is "bad". K&K sends a super high-tech installation tool, which basically is just a nail bent at a 90 degree angle, and then you take this putty here and you place the putty on the backside of the transducer. That's the side that has the label on it. You then place the super high-tech installation tool on the back side and that helps you install this right inside there, like that [Robert uses the tool to attach the transducer through the F-hole]. The best place, a recommended place, is right out here at the end of the bridge, and you need to check and see what kind of bracing you have in here. This brace goes here and here, so this transducer fits right up in there.
And as soon as I peel off the double-sided tape, I can just place it right up in there, right at the end of the bridge. Once you've checked the location, go ahead and peel the brown paper off of the double-sided tape and now, use the super high-tech tool to come right in there like that and install it right at the end of the bridge. And with any luck, you can just pull the tool off and the transducer should stay in place. And if you can get a finger in there and just help it seat a little better, that probably works pretty good too. And you want to rinse and repeat on the other side.
And when you install the transducers, you want the wires going towards the rear of the mandolin there, towards the block. And if the putty happens to stay in there, you can just come in with your finger and rub it. Perhaps it comes off and you don't lose it if you drop it in there like I just did, then you have to fish it out with your tweezers. You can come in with your pinky, or any other finger you can get up in there, make sure that transducer seats up in there properly. If you happen to have a little residue from the putty in there, it's okay.
Install the tailpiece
So, the tailpiece presents a problem for us. Either I ream this out or drill it out somehow, or I recess the nuts and the washers into the block itself, just a skosh, which is the easier alternative, in my opinion. If you want to go ahead and ream this out a little bit, you can.
So, what I ended up doing was recessing this a little bit so that the nut and the washers are below this level. That way, the tailpiece can fit flush in the position that it was in. However, there's not much sticking out on the end jack here for the threads to grab the part that the strap goes on. So, what I ended up doing was sanding this down just a little bit so I have enough to grab on there. And there it is. Now I can put the screws back in the tailpiece and string it up. Now, you're going to have to alter either the tailpiece so that this opening is the same size as this and it recesses on down in there, or this, or both. So, that makes it quite interesting. So now, I've got all of the strings back on, I've got it tuned to pitch, and I've got it plugged into my amp just to test it [Robert strums the mandolin]. And life's good.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
