2-band bass guitar onboard preamp - Page 3

Brion55 · 26th March 2006, 02:24 AM

No fun getting old, blind and... and... oh, forgetful!

DolbyR · 3rd April 2006, 04:00 PM

ok, let me come to spam your thread

Haven't been at diy audio for quite a while but glad i found this. It looks perfect for my purposes, i'm planning Kreutzers preamp for quite long but never got to make it. I tried a regular baxandall integrated in the bass but it just lost too much from the signal.
So i guess i'll be building this one soon too

probably with the 3-band EQ but it still depends whether i put the gain switch or something as i have only place for 4 knobs. I could use push-pull knobs though if the place gets too small.
One thing i was wondering, would a balance pot between my two P/U's make i good difference or do u guys think its unnecessary?
The bat holder is another subject i must think of also, maybe i could fit it inside the electronic 'cavity' but opening and closing could become a bummer...i could add a recharging circuit though, with the DC jack on the back of the bass

i think my website is supposed to be on the sig so there's some pics of my cheapo bass and the baxandall (i think it was baxandall, cant really remember) anyway...it didn't work out well

Brion55 · 4th April 2006, 11:46 PM

They now make batt holders for guitars to allow easy access. It might be worth the effort.

I put my batt behind the pick guard along with the electronics. It's not very handy for changing, but I only have to do it every 10 - 12 months, even with a lot of use. I check the batt when changing strings.

A balance pot would be hard to do since you want both pickups at full volume with the pot in the mid position. Two volume pots or switches would be easier.

DolbyR · 5th April 2006, 05:44 AM

Yes you're right on that, i currently have two volume pots, but i guess the circuit had to do somhow changed for that? Anywa, i lack of space for pots and i want the 3-band Eq so the only way would be to use p-p pots which are again larger. so i'll just forget this now, although i've wired the bass for 2 separate volumes, i'm actually only using them at the max anyway.
I guess i'll also forget the recharger circuit and if the battery really lasts that well, it won't be a problem as my electronics are on the back of the bass with a cover which opens with 2 screws. not like in strato's under the strings.
I guess i'll have some build pics after its finished, after few days, weeks, or months

DolbyR · 15th April 2006, 02:27 PM

Just one question..at first i thought its just a regular voltage divider in the circuit, by now that i start looking better at it, it doesnt exactly look like it...where does the the battery's [-] pole connect? just through a switching jack to ground?

Nigel Goodwin · 15th April 2006, 02:58 PM

Quote:

Originally posted by DolbyR
Just one question..at first i thought its just a regular voltage divider in the circuit, by now that i start looking better at it, it doesnt exactly look like it...where does the the battery's [-] pole connect? just through a switching jack to ground?

Yes, through the jack to ground, so it switches the power ON when you put a plug in, it's standard practice.

You are also correct in your thought that it uses a simple voltage divider to give a split supply, the two 4k7's.

DolbyR · 15th April 2006, 06:17 PM

thanks for the quick answer..
i'm still not advanced in reading schematics, but from what i understood, only half of each of the 4 opamps in the 3-band version is used...am i correct? a TL071 would work as good then too?

DolbyR · 15th April 2006, 07:24 PM

here's the layout i could manage..looks like ****...got to think what to do about it

Nigel Goodwin · 16th April 2006, 09:09 AM

Quote:

Originally posted by DolbyR
thanks for the quick answer..
i'm still not advanced in reading schematics, but from what i understood, only half of each of the 4 opamps in the 3-band version is used...am i correct? a TL071 would work as good then too?

It would, but the original circuit only used TWO eight pin chips, each with two opamps in! - this is done to save space.

DolbyR · 16th April 2006, 04:19 PM

I'm getting a hard time in figuring how to use the opamps like they should

would this look ok?

4th April 2006, 11:46 PM	#23
Brion55 diyAudio Member Join Date: Apr 2005 Location: Kansas	They now make batt holders for guitars to allow easy access. It might be worth the effort. I put my batt behind the pick guard along with the electronics. It's not very handy for changing, but I only have to do it every 10 - 12 months, even with a lot of use. I check the batt when changing strings. A balance pot would be hard to do since you want both pickups at full volume with the pot in the mid position. Two volume pots or switches would be easier. __________________ How do I put the smoke back in this thing?

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3rd April 2006, 04:00 PM	#22
DolbyR diyAudio Member Join Date: Oct 2005	ok, let me come to spam your thread Haven't been at diy audio for quite a while but glad i found this. It looks perfect for my purposes, i'm planning Kreutzers preamp for quite long but never got to make it. I tried a regular baxandall integrated in the bass but it just lost too much from the signal. So i guess i'll be building this one soon too probably with the 3-band EQ but it still depends whether i put the gain switch or something as i have only place for 4 knobs. I could use push-pull knobs though if the place gets too small. One thing i was wondering, would a balance pot between my two P/U's make i good difference or do u guys think its unnecessary? The bat holder is another subject i must think of also, maybe i could fit it inside the electronic 'cavity' but opening and closing could become a bummer...i could add a recharging circuit though, with the DC jack on the back of the bass i think my website is supposed to be on the sig so there's some pics of my cheapo bass and the baxandall (i think it was baxandall, cant really remember) anyway...it didn't work out well

5th April 2006, 05:44 AM	#24
DolbyR diyAudio Member Join Date: Oct 2005	Yes you're right on that, i currently have two volume pots, but i guess the circuit had to do somhow changed for that? Anywa, i lack of space for pots and i want the 3-band Eq so the only way would be to use p-p pots which are again larger. so i'll just forget this now, although i've wired the bass for 2 separate volumes, i'm actually only using them at the max anyway. I guess i'll also forget the recharger circuit and if the battery really lasts that well, it won't be a problem as my electronics are on the back of the bass with a cover which opens with 2 screws. not like in strato's under the strings. I guess i'll have some build pics after its finished, after few days, weeks, or months

15th April 2006, 02:27 PM	#25
DolbyR diyAudio Member Join Date: Oct 2005	Just one question..at first i thought its just a regular voltage divider in the circuit, by now that i start looking better at it, it doesnt exactly look like it...where does the the battery's [-] pole connect? just through a switching jack to ground?

15th April 2006, 06:17 PM	#27
DolbyR diyAudio Member Join Date: Oct 2005	thanks for the quick answer.. i'm still not advanced in reading schematics, but from what i understood, only half of each of the 4 opamps in the 3-band version is used...am i correct? a TL071 would work as good then too?