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Tobias/Bartolini inquiry

abarson

abarson

Nov 6, 2003
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Santa Cruz
#1
I've got one of the older Tobias Growlers, with the single volume, balance, two stacked bass/treble controls and two toggle switches. My understanding is that the pickup and EQ are from Bartolini.
My problem is that this bass no longer has any power to it, no "oomph". The controls all operate as they are supposed to, but the whole thing just lacks the powerful output it had when I bought it. I've replaced the batteries and changed strings (obvious and simple), but it didn't do much. Anything else I should be checking?
Does anyone have a wiring diagram for this rats nest? It might give me a clue what to check, even though the controls are working.
If that fails, does anyone have a good replacement recommendation?
:help:
 
#2
abarson said:
I've got one of the older Tobias Growlers, with the single volume, balance, two stacked bass/treble controls and two toggle switches. My understanding is that the pickup and EQ are from Bartolini.
My problem is that this bass no longer has any power to it, no "oomph". The controls all operate as they are supposed to, but the whole thing just lacks the powerful output it had when I bought it. I've replaced the batteries and changed strings (obvious and simple), but it didn't do much. Anything else I should be checking?
Does anyone have a wiring diagram for this rats nest? It might give me a clue what to check, even though the controls are working.
If that fails, does anyone have a good replacement recommendation?
:help:
Click to expand...

Have you moved the pickup height?

You could also check if the preamp has internal trim pots to boost the gain.
 
#3
If the controls are working don't mess with the rats nest unless you want to learn how to rewire a preamp vs. playing your bass. As far as I know, the Bart preamp can have a faulty component, but that would be inside the epoxied "brick" and the only problem I had with a Bart pre was battery consumption went way up as a result. If you think it's the the electronics, and are up for an adventure, you can swap the preamp. Suggest you
research this before you start tearing that apart. Maybe take a picture of the rats nest and see if someone can identify the pre. Is it a domestic made bass or import?
 
#4
I can confirm that I haven't changed the pickup height. Any recommendation of what the appropriate gap between the pickup top and the bottom of the strings should be?

It does have trim pots, but if I need to boost the gain, something has changed over time. Is that typical?

This is the first generation Growler, made in Tennessee. Someone on a different forum thinks that it is a Bartolini DNTBT-18, if that helps.
 
#5
Well, it turns out that the 9 volt batteries were both below 7 volts, but they're only a couple of months old. I wouldn't expect them to drain so quickly. I've been careful not to leave the cable in the jack when I'm not playing. I poked around looking for anything that may be shorted to ground and came up empty-handed.

Does anyone know what each of the two trim pots per preamp does?

One more question: is it typical to have multiple ground points soldered to the shielding? I thought the common practice is to bring all those wires to one spot.
 

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#7
I'm following up on the suggestion to check pickup height that sotua mentioned. It's a MM humbucker shape with three screws to adjust height. I raised the screws, but the pickup isn't rising. Are there supposed to be springs that push the pickup up on its screw, or just the foam padding in the bottom?
 
#13
The Growler has 3 individual preamps (2) individual varible frequesncy Mid pre's ( the ones at 12 and 2 oclock) and the big mamajama in the center of the cavity where the pickup connects to, that does bass & Treble. The cavity is fully shielded and grounds at multiple points. The electronics in 1st gen growlers are very complicated, well designed, and VALUABLE, since they can no longer be replaced. The pickup is also actually FOUR individual pickups in one cover. Very difficult to construct and also no longer available to replace. My guess is you got a couple or one bad battery. Bring up the pickup to a good height for correct volume (not too loud) and try it out again. I highly discourage replacing the preamp/pickup The electronics are the heart and soul of the Growler, and coupled with it being well set up, can make for a really great bass. Killer , SNappy and cutting sound.

good luck.

heres a pic of mine.

P1040749.jpg
 
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#15
The Growler (the early models with this particular pre-amp) are really great sounding instruments and a lot of that is due to the Bart pre-amp (I believe that this was Bill's most complicated unit & one of the reasons that it is no longer in production... IMHO) & the really cool four coil (two humbucking pickups in one casing) pickup.

The newer models don't hold a candle to the early Growlers. Totally different animals.

Moonshine :bassist:
 
#16
As stated:
1. Batteries replaced - negligible difference.
2. Ammeter used to make sure that
a) no current is being drawn when the cord is not plugged into the output jack, and
b) no more than 4 mA are drawn when it is plugged into the jack.

How do I further troubleshoot whether the problem is with the pickup (low output from the pickup into the preamp) or that the preamp is kaput, even after I've checked the current draw?

Neither Bartolini or Gibson/Tobias are any help. I'm on the verge of giving up on this bass, but right now it's the only one I own.
 
#17
Did you measure the battery voltage before installing them? It's possible the batteries could be weak straight from the manufacturer. Not common, but possible, and easy to verify.

Failing that, I would temporarily wire the pickup straight to the jack, or to some jumper wires straight to a cable. Of course, this may not be feasible or agreeable due to the wiring complexity; I don't know. It all depends on how much you're willing to go to troubleshoot. But that's the only way I know of to determine if the problem is with the pickup or the preamp.
 
#20
Yeesh! @Bruce You want me to remember what I did 6 years ago?! Even 6 days is pushing it...

If I recall, changing the pickup height and changing strings (Dunlop Super Bright steel) got me out of the hole. I remain unconvinced that the output is correct, but I'm kind of used to it. A $50 Silvertone P-bass clone has way more signal strength.

That said, it's still my only bass.
 

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