DIY Stingray 3EQ Preamp - Page 2

domdec314 · #21 05-22-2012, 11:42 PM

Found a major error in my perfboard layout. I forgot that the official layout shows the bottom of the board, so my design is flipped. This would've been okay except it keeps the chip from working right. My layout is now fixed.

UPDATE: I fixed two small issues with the traces. I've also put in my order at Mouser. It won't be long 'til I have this thing built!

domdec314 · #22 05-28-2012, 05:24 PM

Well, I have good news and bad news. The good news is that I have the 3-band preamp built and it works. The bad news is that it isn't quite working right. It's pretty close though!

The problems I'm having are: the treble pot is scratchy when I turn it, the sound cuts out for a second when I adjust the volume pot, and the passive signal is getting through when the battery is unplugged. I'm positive however, that these issues are soldering issues as my solder tip is worn out. When I get my new soldering tip in the next two days I'll redo all the solder points and see if that fixes it. Besides those issues, the preamp more or less works. The tone pots do what they're suppose to do and it sounds good. Shouldn't be long before its done!

EDIT: I've read a few posts of people saying their Stingrays still make noise without a battery, just that the signal is really low and the eq knobs don't work. I guess that's not an issue then. Now I just need to figure out why the two pots are crackling.

EDIT2: I feel a bit dumb now. The two pots were just dirty. A quick spray cleaned them right up. I can fairly confidently say, this circuit works!

domdec314 · #23 05-28-2012, 10:08 PM

Okay, here's some pictures as proof that this exists

Here's the whole mess:

Here's the close up of the front:

Here's the back:

I'm working on it outside of the bass since it only has whole for three knobs (G&L L2500 Tribute). I just ordered a concentric 50k pot and knobs on eBay. I may actually put in a pedal box for now, just to make it easier to mess with. I'll try to get some sound samples up soon as well.

domdec314 · #24 05-28-2012, 11:34 PM

Just recorded some samples. I made one for each eq knob. In each, you'll hear a pattern played 3 times: once with the eq flat, once with the particular knob cut all the way, and once with that knob boosted all the way. This should give you a general idea of how it sounds.

I'm playing a G&L L2500 Tribute with both pickups in parallel mode and plugged directly into the preamp of my sound card. No effects were added.

TREBLE KNOB:

http://soundcloud.com/highmileage/3-band-pre-treble

MID KNOB:

http://soundcloud.com/highmileage/3-band-pre-mid

BASS KNOB:

http://soundcloud.com/highmileage/3-band-pre-bass

johnk_10 · #25 05-29-2012, 12:01 AM

it sounds great! nice job.

Stealth · #26 05-29-2012, 05:13 AM

Sounds smashing.

SteC · #27 05-29-2012, 12:00 PM

Quote:

Originally Posted by Stealth

Sounds smashing.

domdec314 · #28 06-07-2012, 03:46 PM

Well, I finally got the preamp inside my bass. I had to order new pots because the Alpha pots I had were too short to fit through the body. I also had to order a concentric pot so I didn't have to drill a new hole. Here's the finished product:

I'm really enjoying this preamp more than I expected. I love being able to adjust the Mid on the fly. I would definitely call this project a big success!

Stealth · #29 06-07-2012, 05:22 PM

So, if all the schematics, BOMs and PCBs/layouts are correct, time to save this entire thread for posterity.

lucam · #30 06-15-2012, 12:14 PM

Just wanted to thank the community

Thank you all guys, thanks domdec314! =)

EricssonB · #31 06-15-2012, 03:50 PM

Yeah I came across this last night in my search to mod my J. Figured that I could make a pair of these inside of an aluminium stomp box with true bypass for less than $30. So, gonna base it off of this -- then never pay trade prices for a prebuilt preamp, ever. Didn't realise how simple they are.

To the OP: are all of the component values accurate? I've been having a hard time finding a 100pF cap and 6.4k resistor. And do you mean 500k for the volume pot?

domdec314 · #32 06-15-2012, 05:32 PM

Quote:

Originally Posted by EricssonB

To the OP: are all of the component values accurate? I've been having a hard time finding a 100pF cap and 6.4k resistor. And do you mean 500k for the volume pot?

I can confirm that the values work, but I can't confirm that they are accurate as I don't own a Stingray to compare against. I was able to find all parts at mouser.com. As for the volume pot, it should be 25k.

j3ss3 · #33 06-16-2012, 02:00 AM

How much tweaking would it take to fit a jazz? (frequency-wise)
I never played a MM, so I am not familiar which center-frequencies the preamp boosts/cuts.

Thanks!

EricssonB · #34 06-16-2012, 04:02 AM

Quote:

Originally Posted by FunkMetalBass

As much as I love the occasional exploding cap, I do appreciate that. Thanks.

EDIT: I guess I could have just looked at the schematic you linked to in the original post. Whoops.

Phew.

Just ordered parts for four of these.

*attention to detail*

EricssonB · #35 06-18-2012, 03:41 AM

This program is such a hassle. Ended up being so laggy, five seconds between a click and a response. I printed up yours, turned it sideways and added a 3PDT and in/out jacks. Care to proof it? Took pains to make it 1:1+mods.

My friend wants one of these and a 2-band version, so I figured I'd get some practice at the program. He's fronting the money for it and I'm putting them together. Making four.

"Fæpbœx III" is the official name. The 2-band will be "Fæpbœx II" obviously. Built into a stomp pedal and done in these colors:

MKD · #36 10-29-2012, 02:32 AM

ok, so forgive me for sounding completely useless, but where do you wire in the pickup to the preamp circuit?

I'm super keen to put one in a 4str OLP MM, the extra knob could go where the input jack is now (on control plate) and drill for another input through the body - this probably requires an actual 'real' humbucker though too...?

cheers,

delta7fred · #37 10-29-2012, 03:23 AM

Quote:

Originally Posted by MKD

ok, so forgive me for sounding completely useless, but where do you wire in the pickup to the preamp circuit?

I'm super keen to put one in a 4str OLP MM, the extra knob could go where the input jack is now (on control plate) and drill for another input through the body - this probably requires an actual 'real' humbucker though too...?

cheers,

On the perfboard layout in post #1 it is the white wire at the top left corner for the pickup hot connection and ground for the cold.

The OLP SR4 has a humbucker in, but it is not the same as a real MM humbucker. It will work ok but not sound exactly the same.

MKD · #38 11-14-2012, 05:16 PM

im having a really hard time locating a 500k resistor in NZ, a 510k or 560k are about the best i can do - unless i use a trimpot or something like that - does anyone have any suggestions for substitutions?

cheers, MKD

johnk_10 · #39 11-14-2012, 05:27 PM

IIMO, a 510K one would work just fine.

MKD · #40 11-14-2012, 07:32 PM

ok one more...i can get either 6.2k or 6.8k resistors in place of the 6.4k one shown...any ideas as to which is best suited?

and - the top left white wire in post #1 goes to the pickup - so is the one that comes off the volume pot the hot output to the jack plug?

cheers, and sorry for all the q's -

ps anyone in NZ have a SD SMB 4a basslines for sale - cheap...?