• 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.

Building a bass with an onboard tube pre

T

TheBassBloke

Apr 23, 2009
83
0
Sydney, Australia
#1
Hey,

I'm thinking about building a bass with an onboard tube preamp. I'm thinking of using a 12AX7 just because its small and easy, and low voltage. I was thinking of cutting a perspex window into the body of the bass and illuminating it so people can see my valve power :bassist:

what do you think of idea? anyone?

-T
 
#2
There's a lot more involved with using a tube. The heater voltage is low, 12v, but that would require an outside high amperage power source. Think wall wart and extended cord.

Not to mention to make the tube anything but a fancy (and HOT) lightbulb, you'd have to hide a lot of complicated circuitry (basically a tube boost pedal or some decent sized circuit) within the body. Dangerous voltages would ensue as well.

Rickenbacker made some lightshow guitars back in the day with lights under the top. Really, really cool! You could try to just emulate those except with tube - lookin' lights...

Sorry for like 5 edits. All afterthoughts. :p
 
#7
I'm not sure how they sound (I've never tried one myself), but some Takamine acoustic guitars have a "cool tube" 12ax67 preamp. So, I guess you could power one off of 1 or 2 9volt batteries- but I have to wonder just how great it would sound...
 
#9
Hi.

There has been a few pics of a German (IIRC) bass manufacturer who has an inboard tube pre. Not sure whether it was the above link, the bass and the pre looked different IIRC.

This is actually something I've been planning to do for a long time. Phantom powering is possible and according to my calculations would even work ;).

Besides the 6/12 V heater, You do need the plate voltage too. That's anywhere between 110V and 300V typically. The characteristics of a tube change quite dramatically when the plate voltage changes.

You have a lot of designing and testing to do, and it might not be "worth" it. But just think how cool it would be :).

I'd say Go for it.

Regards
Sam
 
#11
zombywoof5050 said:
Isn't it best for a tube to stay stationary?
Inside the bass it would get a lot of physical shock from all the moving around, which I think would be bad for the life of the filaments, wouldn't it?
Click to expand...

Depends on if you groove or if you rock. ;)

They're pretty resilient buggers. (Just think about their average lifespan) The kind of shocks it would be getting with a player, in my case, wouldn't be shocks at all. I don't tend to slam my bass on my legs, into an audience member, or into a guitarist's face all that often. I'm pretty gentle with them, especially if I put that kind of man hours into them.

However, there's the other side of my playing. If I'm not trying to emulate a deep SVT tone at the time, I'd probably be playing something a little more...mobile. It'd work out for me in theory. :D

All in all though, I'm now interested in this idea! I'm going to look into a making a miniature pre circuit. I'm not sure if I'd want it as a true pre driver, to drive it, or just to look cool. :confused:
 
#12
It's dumb, but undeniably cool. Really cool. As far as rough handling-it wouldn't be any worse than what a tube head typically sees. And heads are usually subjected to intense vibration from sitting directly on cabs, unless you isolate them. But it's dumb. And cool.
 
#13
christw said:
There's a lot more involved with using a tube. The heater voltage is low, 12v, but that would require an outside high amperage power source. Think wall wart and extended cord.

Not to mention to make the tube anything but a fancy (and HOT) lightbulb, you'd have to hide a lot of complicated circuitry (basically a tube boost pedal or some decent sized circuit) within the body. Dangerous voltages would ensue as well.
Click to expand...


You could (and probably would) treat it the way tube microphones are built: the tube and some minimal circuitry are in the mic, but the power supply is an outboard unit, connected via a multiconductor cable that carries both reasonably high voltage to the mic, and audio from the mic.

So imagine your bass with a 5-pin XLR jack.

Is it a good idea? From a performance/sonic/practical standpoint, I think it's foolish. From a marketing standpoint I think it's brilliant. Money wins; go for it. Just remember to patent your ideas.
 
#14
You are making it more tempting for me to waste more of my time and trickling money building such a thing! :D

I'll be honest-if I don't end up killing my brains at my friend's 22nd birthday tonight, I'll be using them planning a tube pre circuit.


Edit: So, thinking without the specific circuit yet, I already have a very tempting design in mind. If any true engineer wanted to give this idea a swing, I'm willing to do so! (I was an EE pre with a lot of independent reading and experience who switched majors recently. I could use some wisdom...)
 

Latest posts

Top Bottom
Back