Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Guitars => Topic started by: jjasilli on June 27, 2016, 10:21:59 am

Title: Bill Lawrence Soundhole PU mod
Post by: jjasilli on June 27, 2016, 10:21:59 am
I have 2 Bill Lawrence Soundhole PU's since the '70's.  To me they are under-rated and sound as good or better than anything else.  I hardwired one into an endpin jack in my Martin D-28.  Sounds good, but there is always a problem with lack of a handy vol. control for live acoustic gigs.  These PU's can be had cheap on eBay.


So I modded the other Bill Lawrence Soundhole PU and tried it in my Sigma as a test run.  The Sigma sounds better through the PU into my Alamo Capri amp than it does acoustically; and this is corroborated by my wife!

I used the Schatten 500K thumbwheel control pots, which are ungodly expensive:  http://www.stewmac.com/Pickups_and_Electronics/Components_and_Parts/Potentiometers/Schatten_Thumbwheel_Controls.html?utm_source=google&utm_medium=shopping&utm_campaign=2016-06-gp&gclid=COHOm-y_yM0CFRJbhgodMN8Lmg (http://www.stewmac.com/Pickups_and_Electronics/Components_and_Parts/Potentiometers/Schatten_Thumbwheel_Controls.html?utm_source=google&utm_medium=shopping&utm_campaign=2016-06-gp&gclid=COHOm-y_yM0CFRJbhgodMN8Lmg)

There is now a vol & tone control, with Duncan treble bleed mod.  The components are hotglued to the rear of the PU.  If it works out on stage I'll do the same mod to the PU in my Martin.
Title: Re: Bill Lawrence Soundhole PU mod
Post by: John on June 27, 2016, 07:44:32 pm
Cool! I've got a Woody in my old Gibson, but it's much clunkier than yours. I might get one of those to try. The ones listed on eBay have volume control now too.


I also had an under-bridge pup installed, but the bottom 3 strings have much more volume than the top 3. Maybe it's installed back'ards, or maybe I have to fiddle with it some more.
Title: Re: Bill Lawrence Soundhole PU mod
Post by: jjasilli on June 27, 2016, 10:04:39 pm
Just came back from a jam, where I tied it out in public.  It's OK. 

Though the Bill Lawrence pups look sleek, the spring attachment is less than ideal.


I've seen the vol control on the new Lawrence pickups.  Don't know if the new pups have the same tone as the vintage ones. 

Under saddle pickups can be fussy and a tricky installation.  Actually the whole amplified acoustic thing can be a quagmire.  Sometimes there's no getting around eq to balance the strings, etc., especially for piezzo pups.
Title: Re: Bill Lawrence Soundhole PU mod
Post by: HotBluePlates on June 28, 2016, 12:53:26 am
Did you ever try a set of electric guitar strings on your acoustic?

With a magnetic pickup, the string only senses the steel core of the wound strings, which makes the high E & B jump way out front. It seems like using strings intended for magnetic pickups would help matters...
Title: Re: Bill Lawrence Soundhole PU mod
Post by: jjasilli on June 28, 2016, 08:23:15 am
Yes, but it's the other poster John with under saddle piezzo -- not magnetic -- PU that has the string imbalance issue. 


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That said this vintage magnetic Bill Lawrence PU seems to have the typical mag PU problem of a loud B string.  My other vintage Bill Lawrence PU does not seem to have this issue. 


Bottom line.  This system is imperfect, but it works probably about as well as any other.  It has the virtue of simplicity: plug & pay with vol & tone control; standard guitar chord into any hi Z input; no extra preamp, etc.

Title: Re: Bill Lawrence Soundhole PU mod
Post by: John on June 28, 2016, 09:05:11 pm
Quote
Under saddle pickups can be fussy and a tricky installation.


Yup. I remember reading that my problem is really common, and I believe the fix is to gently file or sand down the pickup so it fits evenly, "loosely" in the cavity under the bridge. When I get around to putting new strings on I'll take a look at it again (after more googling).


The Woody has great sound, but like I said, it's chunky. Or maybe I'm just fussy.
Title: Re: Bill Lawrence Soundhole PU mod
Post by: jjasilli on July 01, 2016, 09:01:38 am
I think it's important for the bottom of the saddle slot to be perfectly level. This is luthier grade work.  Basically, you need a Dremel tool mounted in a routing base, and a saddle slot jig.  The bit diameter must be smaller than the saddle slot width. 


Also the bottom of the saddle itself must be perfect.  Sometimes the saddle leans a bit toward the nut.  If so, I think the bottom of the saddle needs to be angled to compensate, so it's parallel to the flat bottom of the saddle slot.  Then there will be even pressure across the entire surface area of the undersaddle PU.  All this is easier said than done.  I haven't tried it. 
Title: Re: Bill Lawrence Soundhole PU mod
Post by: John on July 01, 2016, 07:10:37 pm
Oh boy.


Maybe I'll just live with it.  :laugh:
Title: Re: Bill Lawrence Soundhole PU mod
Post by: jjasilli on July 11, 2016, 11:35:39 pm
Update --  it works fine through a PA.  I now have vol & tone controls right on the acoustic guitar.