For quite a time I´ve been searching the internet for archtop guitars with an acoustic PU-System. This would be ideal for my gig, because I play a lot of rhythm guitar and need to switch to an electric sound inbetween (50s and 60s swing and rock´n´roll). The only probably suitable guitar I found, was the YAMAHA AEX 1500, which has an on-board acoustic PU-System (end-to-end rod pick up under the bridge). Unfortunately this guitar isn´t built anymore and hard to get. I´d rather have a Gretsch-Type of guitar anyway rather than such a modern jazz box. I also found quite a few posts on the internet asking about installation of acoustic PU´s in archtops, but with no useful answers or results, so I decided to find out myself if a self-installed piezo works.

I tried a Shadow archtop bridge (similar to the YAMAHA AEX 1500 bridge) and a Shadow SH710 small spot double transducer. The results were both very insufficient for my purpose, but I won´t deepen my thoughts to that here.

The final solution was a Schaller "GTMP" piezo bridge. This is a tuneomatic bridge with one piezo for each string which is made for a Les Paul-type guitar. Fortunately this bridge fits perfectly on the wooden part of GRETSCH G5120 bridges! For other archtops it might have to be fitted.

These are the specifications I want:

- I want the modification to be reversable (non-destructive), meaning no on-board pre amping or drilling holes into the guitar.

- I need to switch between the piezo and magnetic PU´s and compensate the sound difference. I play directly into the mixer and use an amp simulation for the magnetic PU part. If desired, I want to be able to split the PU´s and lead them to different amps/mixer with an A-B-box and Y-cables etc.

The guitar modification

First of all I mounted the new Bridge on my G5120, led the cable through the f-hole and soldered the end to the tip of a stereo jack. The magnetic PU output (that was connected to the old jack) I soldered to the sleve-part of the jack.

Very important: be sure to place the Bridge with the screws facing the bigsby.
This may be the opposite way of the original bridge. I tried it the other way around first and the sound was very thin, trebly and useless. I was about to throw the bridge away, but turning the bridge made a drastic difference.

That´s it!

Due to bad access to the interrior of archtops, I made a helpful little tool by soldering a string to an old tip of a guitar plug. This way you can lead the socket directly to the hole. A pair of tweesers are also essential for grabbing stuff that falls into the guitar :)

The switching part

For an all-purpose setup you would need a switch box with a stereo input jack, mono output jack and for send - return jacks for the filters. For this setup you would have 3 pedals.

ARTEC SE-OE3 modification

My thoughts were: On the acoustic part (green) I only need an EQ. So why don´t just modify the EQ to my needs. Notice, this won´t be a sound modification of the EQ, just a switching improvment.

This means:

- break the normal bypass lead.
- apply a send and return socket (I used cinch because they´re smaller)
- join the sleeve of the input (magnetic PU) to the send socket.
- modify the switch

I use an ARTEC SE-OE3 acoustic EQ with true bypass function. Many other EQ´s can probably be modified in a similar way.

ARTEC SE-OE3 - unmodified

(interior)

Step 1:
Cut the circuit paths to eliminate the original bypass function (red circle).

Step 2:
Solder the battery earth to the middle sleve of the output jack (black wire; battery will disconnect when you pull output plug).

Step 3:
Connect the "send" cinch socket with the middle sleeve of input jack (#1 orange wire).

Step 4:
Connect the "return" cinch socket with the contact of switch (#2 orange wire).

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