ikay

This should help - https://forum.gibson.com/topic/62347-thunderbird-pro-wiring-diagram/

If you want better control of mids then something like the John East Mid Sweep module would be a better bet than a low pass filter https://www.east-uk.com/product/mid-sweep-01/

I recently bought a state variable low-pass filter with variable Q from Helmuth Lemme. Details here - https://www.gitarrenelektronik.de/produkte/aktive-elektronik/state-variable-filter-detail. High quality electronics and reasonably priced. Intended for onboard installation but I configured mine as an external pedal to have the flexibility to play around with different basses. Works great. Freq range is from 300Hz to 5kHz. Q factor is continuously variable (weak to strong) with a pot or you can use a 3-position mini-switch. There's also an Alembic style filter called JTEX Distiller made by a chap in Canada available on ebay: https://www.ebay.com/itm/JTEX-Distiller-Alembic-style-Resonant-Low-Pass-Filter-for-Basses-VIDEO-DEMO-/233803173958

The paint on mine (ex BreadBin) is quite thin and showing signs of wear in places but it has a lovely soft worn-in feel. Here's a pic of the top edge. Personally I prefer necks that have been well played and naturally worn in. Like an old pair of slippers.

Thanks for that, it looks like a great bit of kit.

How do you find the Blackbird tube preamp? I'd be very interested to hear some sound demos if you have anything? I've looked on youtube but can only find demos with guitar, nothing with bass.

The original Gibson mudbucker sure had some hefty coils!

That's interesting. Mine dates to Aug 2004 which bears out the switch to parallel.

I think the USA SUB is wired in parallel, same as a regular SR. Mine certainly sounds that way. The extra thump is most likely down to the 2-band eq which works quite differently to the 3-band.

I'd like to hear a demo of the vViper bass but can't find anything on YT. Can you point me to any demos itu?

Happy Birthday! What's it like to be so young, I'm way ahead of you 😄

I found an LM Tube 800 circuit diagram here if that's of any use - https://el34world.com/charts/Schematics/files/_miscellaneous/Little_mark_tube800_sm.pdf

The more I look at reference pics the more I'm coming to think the variations are just down to the vagiaries of production methods in the 60s. For example, there are plenty of Artist models with the same tailpiece and neck positioning as my German/Euro model (1965 btw). There's even one on the vintagehofner site with the same tailpiece position as mine but the same neck position as yours - a hybrid (pic below)! I think the clear lacquered neck on yours probably does support the idea that it's an Artist model though.

Here's another comparison pic - Artist at top, then yours, then mine (which is a native German model). Yours matches the Artist with the bridge being further away from the endpin and the neck being set correspondingly further out of the body. Add the lack of a neck rout and I think it's pretty conclusive that yours is an Artist. Now all we need to do is get to the bottom of the original paint job being white rather than red 🤔!

Just a one off then by the look of it! Re the lack of a neck pickup rout, I just found this pic of a Hofner Artist in the process of being restored. The Artist was the Selmer version of the 185. Most of them didn't have the slider switches and ... drumroll ... it looks like the neck pickup was mounted to the pickguard as there's no rout.

It's all very mysterious, but I agree it does look original. Does the neck heel show any signs of having been redrilled? Here's a pic of mine for comparison. I'd expect yours to show the holes repositioned towards the heel end with more overhang of the body/neck join.

Nice job. I'm still a bit baffled by the lack of an original neck pickup rout!

Ah, well that removes nut issues from your list which at least narrows it down to neck relief, string action or frets. As you've already raised the string action that leaves neck relief or frets. If the bass has seen a lot of use, the lower frets are generally the first to show signs of wear so that's the first thing I'd check. With a fret rocker if you have one, or a short straight edge (10cm or so - enough to cover 3 frets). If that doesn't show up any high/low frets then your probably right in thinking a small tweak of the trussrod is what's needed. Although that depends on how much relief you've already dialled in - too much relief will give you other problems. If the neck is currently pretty much dead flat (or has only the slightest smidge of relief) then loosen the trussrod 1/8 turn and see if that helps. It's easily reversible so no harm in giving it a go.

When you say 'some fret buzz on the 1st fret of the E string' do you mean the first fret buzzes when you play an open string, or that you get buzz when you fret the first string and play an F?

Here's a recent thread that may be of interest -

This article explains what is happening - https://www.premierguitar.com/articles/29161-mod-garage-three-ways-to-wire-a-tone-pot I know it's titled 'three ways to wire a tone pot' and your issue was with the vol pot, but if you look at the 'standard wiring' (top) and swap the hot and cold wires on the vol pot, this is the electrical equivalent of the ''50s wiring' option (bottom). The big difference being that, when the vol is rolled back, the tone control is no longer directly connected to the pickup and this 'decoupling' results in a change in how the vol and tone pots interact with each other. Read the blurb in the article on '50s wiring and all will be revealed!

Well spotted!

It's a beauty. But it does have one heck of a high action!