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phil mailloux 15th March 2006 11:54 PM

2-band bass guitar onboard preamp
Hi guys,

First post, new member. I build bass guitars as a hobby, the whole shebbang right down to the pickups. I now want to build a preamp.

I'd like to have an active 2-band preamp that fits onboard and runs on one or two 9 volt batteries. I've done soldering before and I can read schems. The building part should be fine but I don't know anything of the theory part.

I've seen albert kreuzer's preamp on the net, it seems very nice and I hear good things about it but it only has one tone knob. Would that be easy to change for treble and bass knobs?

Does anyone have schems of 2-band bass preamps that fit the bill that should work well?

thanks for the help

anatech 15th March 2006 11:57 PM

Hi displaced Phil! ;) ,
Welcome to the forum! I bet the weather is nice down in Oz.

Just wanted to welcome you here. I'm sure others can help with what sounds like an op amp or discrete solution. Which way are you more comfortable? What levels do you want to see?


wxn 16th March 2006 06:29 AM
Basic design. The tone stack can be any design available, it soesn't really matter. Btw, do you want separate tone controls for each band? Anyway, these circuits are so simple that almost any combination will work :) And if you feel unsure about inventing things, download some simple SPICE simulators to make sure the new circuit will operate like it should before even building it :)
Good luck

lndm 16th March 2006 06:36 AM

Yes, welcome!


Originally posted by anatech
I bet the weather is nice down in Oz.

Umm... its raining!

Throw your search engine toward 'Baxandall tone'. This is the traditional tone stack and it can be hitched to just about anything.

phil mailloux 16th March 2006 12:39 PM

Thanks for the input guys. I'm prefectly fine with the kreuzer preamp if a baxendal can be put in place of the tone pot.

Only problem is, I don't know jack about how to do that. that's why I was hoping one of you guys might have a similar circuit around that would fit the bill where I would only need to solder up components based on the schematic

Anybody feel like giving me a newbie's course on how to stick treble and bass pots on that circuit? :blush:

Nigel Goodwin 16th March 2006 01:58 PM

Why don't you check out his main preamp here which has full Baxendall tone controls, even with switchable mid!. As you're using two 9V batteries, it's trivial to use the tone control section from it.

Brion55 16th March 2006 03:14 PM

2 Attachment(s)
Here's one that I have used for many guitars and basses. You can easily change the EQ points for guitar or bass.

phil mailloux 16th March 2006 07:03 PM

That looks like a good one Brion. You've built it a couple of times already?

Does it sound good?

Brion55 16th March 2006 10:46 PM

2 Attachment(s)
I've built about 20 of 'em, and they sound great. You can use a NE5532 or better for lower noise, but the LF353 works pretty good. Under normal use, the battery lasts a long time. I normally make mine unity gain, or a slight gain so it doesn't overload effects or amps.

Here's the "big brother" with a 3 band EQ. I've only built one of these. It's very nice.

phil mailloux 17th March 2006 10:35 AM

I really like that 2-band preamp Brion. I'd like to try building it. Do you have any photos of the end product? I'd be curious to see that.

I can easily find the 50k pots for the treble and bass but I've never seen a 10k pot in a guitar-type pot (like cts pots) where did you find yours?

I'll have a look at all the components and try to scrounge them up. i think i'll definitely be playing around with that in the next week.

If you've got any other usefull tips or tricks or even pcb or perfboard diagrams i'd love to see it/them too :D

thanks again

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