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How does your wiring compare with the attached pic?

This is probably what you have already but there are several schematics in this post - [url="http://music-electronics-forum.com/t35139/"]http://music-electronics-forum.com/t35139/[/url]

If you change the preamp bear in mind that you also have a piezo which won't be accommodated by a standard preamp configuration.

Probably best to contact Yamaha tech support. According to the TRB-P service manual there are four different pot types: Vol - 5KA (presumably 5K audio but that's an unusually small ohm value) Bal - 20KB (dual blend pot - presumably 20K lin) EQ - 50KW (same pot for T/M/B - presumably 50K lin) Piezo mix - 20KB (presumably 20K lin) So depends which one needs replacing. It's not clear from the tech notes whether the pots are mounted directly to the circuit board or not (in which case you'd need a different different type to a regular free standing pot)

The Lakland LH3 wiring diagram is here - [url="https://www.lakland.com/tech-docs/LH-3%20Wiring%20Diagram%204-07.pdf"]https://www.lakland.com/tech-docs/LH-3%20Wiring%20Diagram%204-07.pdf[/url] . It would be pretty straightforward to add a passive tone in front of the preamp (after the vol and blend pots). The issue would be where to mount the extra control. Stacking the vol/blend to free up a hole for the tone would be ideal but not sure if that sort of pot configuration is available. Alternative would be to stack the vol/tone. A guitar tech should easily be able to sort you out.

[quote name='3below' timestamp='1462825084' post='3046103'] At the moment I am exploring some solutions to this end, possibly leading to the 'Uprighter' pedal[/quote] 3below, I'd be interested to know the outcome of your experiments. I'm intrigued by the possibility of some sort of upright simulation using convolution reverb and impulse responses from an acoustic DB. I've seen various posts on the web in this vein but no mention of end results.

I got a K&K BassMax for my cheap old plywood DB. Reasonably priced, easy to fit and does the job - [url="http://www.thomann.de/gb/kk_bass_max.htm"]http://www.thomann.de/gb/kk_bass_max.htm[/url]

[quote name='RhysP' timestamp='1462377610' post='3042543'] Try it as it is & see what happens. [/quote] +1 to this . Actual distance from nut to saddle is generally close to 34" for the G string and a bit longer for the E. Depending on how you measured it, 34.5" sounds like it may be a bit out on intonation.

A little (not a lot!) more info in this thread on a different bass of the same make - http://basschat.co.uk/topic/4168-gould-bass-help/

Sounds like the pickups are out of phase. Reversing the hot and cold wires on the new P pickup should fix it.

This thread may be of interest - http://basschat.co.uk/topic/166853-emg-btc-control-are-you-experienced/

The last page of this Aguilar wiring diagram shows how to add a passive tone control in front of the preamp - http://aguilaramp.com/pdf/support_wiring_obp1.pdf It's just a standard tone control (typically a 250k pot and .47 cap) wired in front of the preamp. You should be able to do the same with a Bartolini preamp. Actual wiring needed will depend on how many pickups and how the existing volume/blend pots are wired. Instead of a full size tone pot just use a small preset pot inside the cavity.

Just bought some DB strings from Alex. Great to deal with, easy transaction and super quick delivery. Many thanks!

Very wierd indeed. Can you post a video?

Looking at pic #5, from the reflection of the strings on the pickup cover, the pickup looks too high to me. As EssentialTension says it's normal practice to set your action and intonation first and then set the pickup height. Try lowering the pickup (both sides/all screws) until it's clearly not interfering with anything (ie. a bit too low). Then do a basic setup - neck relief, saddle height, intonation - to get it playing as you like it. Lastly, adjust the pickup in small increments to get an even output across the strings. Start with the E string side and make sure the pickup is set below the point at which the string hits the pole pieces when playing normally. Then adjust the other screws to balance output with the E string. Remember that any recommended settings you find for pickup height/string clearance (eg. Fender setup guide says 2.8mm on E side and 2mm on G side) are measured from the bottom of the string to the top of the pole piece [u]while fretting the string at the last fret[/u]. The unfretted string clearance is much greater. Pickups don't necessarily need to be maxed as close to the string as possible to get good tone, winding them down a bit can open up the tone and give a more even string balance.

If a string is 'phasing' that's an indicator that it's too close to the pickup. Can you post some pics showing the existing setup (string height and pickup height) on both the E and G side?

Ripping out the existing innards and replacing with a custom foam insert is probably the easiest way to do this. You could get an idea of cost by getting a quote from here - [url="http://www.cutfoam.co.uk/case-inserts.html"]http://www.cutfoam.co.uk/case-inserts.html[/url]. Google 'custom foam case inserts' to find other suppliers

Dimensions here: Ultralites - [url="http://hipshotproducts.com/files/all/ultralites.pdf"]http://hipshotproducts.com/files/all/ultralites.pdf[/url] GB720s - [url="http://shop.sollerguitars.com/product_info.php/products_id/2267gb-720-l-cbk.html/language/en/gb-720-l-cbk.html"]http://shop.sollerguitars.com/product_info.php/products_id/2267gb-720-l-cbk.html/language/en/gb-720-l-cbk.html[/url]

Jeez that spaghetti of wiring is shocking!