Tobias electrics

[Old Fox]

Hi, this is my first post so please excuse any newbie errors.
I have a mid 80’s pre Gibson Tobias that had some electrical repairs done a while back but it’s never been right since, I contacted Michael Tobias directly and sent a few pictures of the wiring and he didn’t recognise any of it 🤔 can anyone recommend a good repair guy that could return it to its original set up, I live on the south coast, close to Brighton.

[Hellzero]

Strange as it's a Bartolini preamp as the ones Mike Tobias put in all his basses.

 

This is not the original for sure as the active/passive switch is now on a push-pull and it's missing the twin buffer, but it's almost like his Bartolini-Tobias preamps.

 

Just wire the switch and replace the push-pull by a standard pot: job almost done and completely done if you add a twin buffer.

 

Check this: https://bartolini.net/builder/mtd/

[Old Fox]

Thanks for the links to the Bartolini wiring diagrams, am I missing something? to my knowledge, my bass has only ever had one battery but the diagrams all show two batteries?

[Hellzero]

These are the preamps for the MTD basses that run on 2x9 Volts (not exactly 18 Volts as it's a direct +9 Volts and -9 Volts).

 

This link was intended in the case you would want to use the actual preamp.

 

To turn it back to the original preamp, you have to use a Bartolini TCT (your bass is an early one) and a dual buffer like the AGDB/918-2, both working at 9 Volts.

 

Here is what Mike says about the pre-Gibson models:

"The original electronics were probably a TCT with some kind of buffer. DTA 1.?, 5 knobs and a switch.

We never made basses with a push pull of any kind. that was Gibson or aftermarket stuff people did.

The original tr (truss rod) wrench was a 1/4” open end wrench you could buy from any hardware store that is why I left the tr nuts sticking out past the end of the board."

 

Bartolini TCT:

https://bartolini.net/product/tct/

 

Bartolini AG(D)B:

https://bartolini.net/product/agb/

 

Edited October 25, 2023 by Hellzero
Slight correction

[Hellzero]

I found this very interesting worthy information on TB: https://www.talkbass.com/threads/80s-tobias-tct-wiring-specs.1467228/

[Hellzero]

Here are two opened lid early Tobias electronics (a bit younger than yours), both with a Bartolini TCT preamp, no buffer, and Bob Lee mod.

 

So simply put a TCT (original with TCT embossed would be the best option, but they are very hard to find) preamp with the mid control and the active/passive switch and your bass will back to its origins.

 

The opened lids:

 

 

 

And the embossed Bartolini TCT:

 

 

I certainly have better images of this 80's embossed Bartolini TCT as I had to make a pedal for a customer with that very preamp inside, but I need to turn the PC on and it's late...

 

And remember that Mike Tobias always reverses the bass and treble pots position on his basses, the treble pot being the closest to the neck.

 

Edited October 25, 2023 by Hellzero
Younger not older

[iplay5strings]

This looks like an early, 2 module NTMB preamp. If your bass still has the early drop shoulder spec duals, mating them to a TCT will get that bass the closest you can get it back to the Hollywood era sound. The biggest thing missing is the Tobias specific mid module that was used for the Tobias TCT circuit. It allowed much more tunability to the mid boost including being able to set how far the bottom of the boost shelf reached into the low mids, as well as creating a tuneable, separate treble boost shelf controlled by the mid knob. You can achieve the treble boost tuneability if you use the 3MC 3 way mid module that has the stock 2K-15K treble circuit separated which means you can bypass it and create your own/one more like the Tobias circuit.