• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

BBE T-MAX owners

I

ivanthetrble

Sep 9, 2002
327
47
67
Orygun
Visit site
#1
I have heard a couple of comments on the sensitivity of the gain control on the BBE T-MAX pre-amp. It seemed like the gain was very sensitive and easy to overdrive. I switched the 12AX7 tube out and put in a Phillips JAN 5751 (only about 70% of the gain of the 12AX7) and wow, big difference! The gain is much smoother and more managable. Much easer to set the gain when playing an 18v onboard pre-amp than with the 12AX7. Sounding very nice today thru a QSC PLX 3002 and a Bergantino HT210. Very nice indeed. :hyper:
 
#7
Mobay45 said:
Thanks for the help guys. I know that "NOS" means new old stock, but what does "JAN" for? Also, do you know how the Sovtek tubes are?
Click to expand...

IIRC, JAN stands for "joint Army/Navy". I think they were made for the military so there seems to be a lot of them available at a pretty good price. Lord Valve is a great source for tubes and advice as is The Tube Store and might also try googling "Electron-valve" to get another good source. I have another pre-amp that I want a bit more gain and the Sovtek 12AX7LPS are a very good choice for that situation.
 
#9
ivanthetrble said:
I have heard a couple of comments on the sensitivity of the gain control on the BBE T-MAX pre-amp. It seemed like the gain was very sensitive and easy to overdrive. I switched the 12AX7 tube out and put in a Phillips JAN 5751 (only about 70% of the gain of the 12AX7) and wow, big difference! The gain is much smoother and more managable. Much easer to set the gain when playing an 18v onboard pre-amp than with the 12AX7. Sounding very nice today thru a QSC PLX 3002 and a Bergantino HT210. Very nice indeed. :hyper:
Click to expand...

I had a similar problem. 5-string Bongo with bass full up just overloaded. The gain knob could only just be off the end-stop. I got hold of a JAN5751, not easy in UK, but it didn't fix the problem. Several emails to BBE brought forth some mod details (component changes/removals). Interestingly the tube stage is almost identical to an Alembic FX2. I did the mods today and it is purring now like a kitten with the original Groove Tubes tube back in. I reckon BBE know about the overload problems with 18-volt basses but have done/said nothing.
 
#11
OBBM said:
I had a similar problem. 5-string Bongo with bass full up just overloaded. The gain knob could only just be off the end-stop. I got hold of a JAN5751, not easy in UK, but it didn't fix the problem. Several emails to BBE brought forth some mod details (component changes/removals). Interestingly the tube stage is almost identical to an Alembic FX2. I did the mods today and it is purring now like a kitten with the original Groove Tubes tube back in. I reckon BBE know about the overload problems with 18-volt basses but have done/said nothing.
Click to expand...

So what kind of mods are we talking about here. Simple things? Do tell!
 
#12
i always thought JAN was short for january...........

BTW, the b-max is IIRC based on the fender tone stack just like the alembic and trace v-type are. i belive the specific circuit was from the showman. IIRC, these were all circuits made available by RCA, (from what i hear in hopes that peopel would design things using them and then need to buy parts and tubes from ....RCA). I think that's also called the Tom Walker design. (maybe he was the cat that worked at rca that came up with it?) in any event, a great sounding circuit.
 
#13
Here you go, very straight forward

R7 changes from a 46.4K resistor to a 68.1K
R10 changes from a 46.4k resistor to a 21.5K
Capacitor C8 and C9 are completely removed

Worked for me. No more overload with Bongo or SR5.

Just done a weeks tour with another band and their bass player used a Rickenbacker though it. Great sound and no problems. For the dates with no DI we used the Sonic Maximiser - Wicked.

Happy soldering :D
 
#14
The problem was the 18-volt electrics of the Bongo was completely overloading the front end, especially if I had the bass control wound up on the Bongo. The gain control could not go above '1'. Now I can go higher. All I can say is carefully remove and change the components, or get a tech to do it, try as see if it works for you.

I think that this sort of thing is very individual. Don't blame me if it doesn't work for you.
 

Latest posts

Top Bottom
Back