PCBs for DIY clone 2-band Preamps

[BassLife77]

Originally Posted by brumshine

I just finished installing my preamp and I just wanted to make sure it's working correctly. I have to admit, to my ears, it sounds great. No buzz issues and I'm still using the stock OLP pickup. I'll try to get some pics up tonight.

If I turn the bass and tone knobs all the way down and only turn up the volume I get no sound. Could someone explain what each pot is actually contolling (boost /cut, # of dbs). Thanks in advance.

I've built several of these and never had that problem. You should still have a strong bass signal with the treble and bass cut. Something might be soldered incorrectly or you missed a ground connection. A common mistake is the treble pot wires are soldered incorrectly to the board. Check for any bridged or bad solder joints with a magnifying glass. also check for any DC voltage coming through the output jack with a MM.

[MuthaFunk]

I just dropped one of these in my new to me used ATK 305



I used the stock pickup coil selector toggle switch and I put a master tone knob before the preamp for a little more control of the highs. I read somewhere that the ATK series of basses have the pickup mounted in the same sweet spot of the Musicman. This preamp really took this affordable bass to the next level!!

Thanks UncleFluffy!!!

I couldn't source the proper pots that were long enough to get through the wood mounting so I had to drill out 1/8" of the wood to get enough threads of the pots poke through to get a washer and nut on there. It was a hassle but in the end I think it was all worth it. Man I love the tone of it now! If memory serves me correct, It's very close to my old Musicman I ended up selling 3 years ago.

[MuthaFunk]

Originally Posted by johnk_10

by the way, if you want to have a hotter output, you can replace the 220K input resistor with a 100K or 150K one for an increase of about 3db. my MM4.4 pickup seemed a little weak, so that what i did on mine and now it has the same output level as my passive p bass.

This suggestion worked great for me as well. I used a 100K and got more gain out of it. Thanks for the tip!

[mastaihei]

I love 2band pre rather than EBMM 3band type too.
My additional recommendation is capacitor varitone switch.In this model,I use "New oak super switch" as varitone slide.

[UncleFluffy]

WE GOT BOARDS!



The next batch are in. PMs will be going out to everyone who's been waiting over the next few days.

[flood]

great to see these are so popular; i too built one from bajaman's layout, but was underwhelmed because of the output level - coming to this thread was a godsend, didn't know about the input resistor mod. i figured it was a mistake on my part, because bajaman's stuff is ace is in general, he's incredibly knowledgeable and helpful and a boon to the FSB community.

one question though - would you change anything for use with a 6 string? i'm guessing my EQ will be a lot more responsive with an increase in output levels, but would you change anything in the EQ section for a 6?

i'm just worried that the very unimpressive korean pickups in my bass will sound even more unimpressive after this, but i'm not spending any more money on a bass that i don't plan to keep. thanks for any guidance!

[Andyman001]

Originally Posted by flood

great to see these are so popular; i too built one from bajaman's layout, but was underwhelmed because of the output level - coming to this thread was a godsend, didn't know about the input resistor mod. i figured it was a mistake on my part, because bajaman's stuff is ace is in general, he's incredibly knowledgeable and helpful and a boon to the FSB community.

one question though - would you change anything for use with a 6 string? i'm guessing my EQ will be a lot more responsive with an increase in output levels, but would you change anything in the EQ section for a 6?

i'm just worried that the very unimpressive korean pickups in my bass will sound even more unimpressive after this, but i'm not spending any more money on a bass that i don't plan to keep. thanks for any guidance!

I think (and am probably wrong) that the bass is +14/-7 db @40Hz; the treb I think is centered @ 10K but I am not sure.

[SGD Lutherie]

Originally Posted by Andyman001

I think (and am probably wrong) that the bass is +14/-7 db @40Hz; the treb I think is centered @ 10K but I am not sure.

The center frequency on the bass control is 50Hz, but it's wide, and goes from 100Hz all the way down to 20Hz.

The treble control does sound pretty high, and I though 10K as well. But it also seems kind of wide and adds some upper mids when you crank it. It's wired up more like a presence control on an amp, and probably does some things to the overall gain structure.

[flood]

thanks for the answers guys will drop the 220k to 100k/150k the next week and see if there's a change.

[SGD Lutherie]

Originally Posted by flood

thanks for the answers guys will drop the 220k to 100k/150k the next week and see if there's a change.

It will be louder.

[joelb79]

Where is the best place to get the parts for building these boards up these days?

[SGD Lutherie]

Originally Posted by joelb79

Where is the best place to get the parts for building these boards up these days?

Mouser is good.

[daveze]

Are all of that recent batch of boards accounted for? I'm keen for a board to go into my Sledgehammer...

[UncleFluffy]

Originally Posted by daveze

Are all of that recent batch of boards accounted for? I'm keen for a board to go into my Sledgehammer...

Nope, there's plenty left. I'll be going through the order PMs this weekend and sending them out.

[daveze]

Champion, thanks for the response.

[daveze]

Has anybody tried much opamp 'rolling'? I'll have a look through my parts boxes but I should have a few of the usual suspects...should also have a number of suitable 'fancy' caps for those that get all warm and fuzzy about such things.

[Passinwind]

Originally Posted by daveze

Has anybody tried much opamp 'rolling'? I'll have a look through my parts boxes but I should have a few of the usual suspects...should also have a number of suitable 'fancy' caps for those that get all warm and fuzzy about such things.

Somewhere in this thread or the predecessor there was a fair bit of discussion on this. I am using an LT1351 in my first build, which was highly recommended, and have a few more types in my parts box for whenever I get around to building my second one. In all honestly, I haven't bothered to even try the LM4250s I bought just before I started my build, because the LT sample chips came in first and I am quite happy with what's in there.

[Andyman001]

Boards arrived.
Gonna play with some solder now.

Thanks, Derek

[SGD Lutherie]

Originally Posted by Passinwind

Somewhere in this thread or the predecessor there was a fair bit of discussion on this. I am using an LT1351 in my first build, which was highly recommended, and have a few more types in my parts box for whenever I get around to building my second one. In all honestly, I haven't bothered to even try the LM4250s I bought just before I started my build, because the LT sample chips came in first and I am quite happy with what's in there.

I have some samples too. Haven't tried them yet. Still have the LM4250 in my personal bass. The 4250 is not a bad sounding chip at all.

[Passinwind]

Just posted some frequency response curve models in the big thread, here.