DIY Stingray 3EQ Preamp

[domdec314]

The TL072 will work perfectly fine. They just consume more power for the benefit of being less noisy.

[eukatheude]

And since i plan on keeping this plugged into the wall it shouldn't be a problem. Thanks.

[domdec314]

The power consumption on this circuit is so small that even if you used batteries, they would still last for months, if not more than a year, regardless of the two amps. A Burr Brown amp, like the OPA2604, would make a more significant dent of the battery life. I believe I've read it consumes about twice as much power as the TL072, but it's a higher quality amp. If you don't plan on using batteries, I'd give it try. I haven't tried it with this preamp, but I had good results using a Burr Brown with the 2 band stingray preamp.

[eukatheude]

I'll see how it goes with this one. I've yet to decide what use to make of it. I have this chinese 7 stringer whose preamp got fried more than an year ago, and the bass has been sitting since. I've yet to decide if i want to put it into the cavity (since it ended up being much smaller than i thought) or make a passive circuit with 500k pots and then feed it to this preamp in a pedal box. But if i like it i'll probably end up making both, since i'd like to try it with my fretless J. And if i make the stompbox version, i'll use the Burr Brown. Do you know of any other good DIY preamps?

[EricssonB]

Originally Posted by eukatheude

I'll see how it goes with this one. I've yet to decide what use to make of it. I have this chinese 7 stringer whose preamp got fried more than an year ago, and the bass has been sitting since. I've yet to decide if i want to put it into the cavity (since it ended up being much smaller than i thought) or make a passive circuit with 500k pots and then feed it to this preamp in a pedal box. But if i like it i'll probably end up making both, since i'd like to try it with my fretless J. And if i make the stompbox version, i'll use the Burr Brown. Do you know of any other good DIY preamps?

Two-band option, based on old SR preamp. Note the mod in post #11: Fæpbœx II: 2-Band Preamp

[eukatheude]

Seems nice, though i have to say i'm a "more knobs is MORE BETTER" kind of guy. How hard would it be to add sweepable midrange? The high pass filter is very interesting, i might do that one too. Why does it use 15V?

By the way, i was wondering how the process of actually figuring out a circuit (take apart a pedal, look at the pcb and draw a schematic) goes. I can't even find where the input is, and following the signal path through both sides of the board seems crazy to me. Are there any surefire methods to do that, or do i just have to be patient?

[SGD Lutherie]

Originally Posted by eukatheude

How hard would it be to add sweepable midrange?

Hard. This uses what's basically a passive tone stack between two op amps. To make a sweepable midrange, you need an active variable filter for the mids.

But you could add a switch to change some parts to alter the midrange frequency.

[EricssonB]

Originally Posted by eukatheude

Seems nice, though i have to say i'm a "more knobs is MORE BETTER" kind of guy. How hard would it be to add sweepable midrange? The high pass filter is very interesting, i might do that one too. Why does it use 15V?

Last year I read into the spec sheets on the TL0XX series and from what I remember, they can handle 5-15 VDC.

I enjoy the high-pass filter as it seems to have a very open effect on the upper registers. Very light and airy, if you will. But, as I play my Jazz bass a lot, it's kinda over the top -- that bass needs a mid control. The two-band works very well on my humbuckered ESP.

I'm considering doing a sort of combination of the two pedals -- but then again, I don't really want to build any more for the foreseeable future. We'll see.

Originally Posted by SGD Lutherie

But you could add a switch to change some parts to alter the midrange frequency.

Yeah, ^that^ is the mod that I'd be doing.

[eukatheude]

Originally Posted by EricssonB

Last year I read into the spec sheets on the TL0XX series and from what I remember, they can handle 5-15 VDC.

So i could just plug a 9V in?

Originally Posted by SGD Lutherie

Hard. This uses what's basically a passive tone stack between two op amps. To make a sweepable midrange, you need an active variable filter for the mids.

But you could add a switch to change some parts to alter the midrange frequency.

That's definitely interesting. I suppose that would be the 8.2nf cap connected to the midrange knob, about in the centre of the board?

[T_Bone_TL]

They (TL062) are actually +/- 15V supplies - ie, up to 30 volts total.

If you are not running on batteries or don't mind changing them, the TL082 series is "generally better" otherwise and can go to +/- 18V for supplies. Generally better is a slippery concept, there are always tradeoffs, or there would only be 5 models of op amp instead of the hundreds or thousands that are actually made.

A nice low-priced opamp with amazingly low noise in the same dual footprint is the LM833, but it has a lower slew rate than the 082 (twice the 062, though) - but not great for battery operation compared to the 062. Tradeoffs.

Edit - LM833 May not be available easily anymore, and here's a better one, still cheap-ish: LM4562. Better slew rate than an 082, better noise than an 833, still the same standard dual outline for drop-in swap ease, and still not nearly as battery-friendly as the 062.

[EricssonB]

Originally Posted by eukatheude

So i could just plug a 9V in?

Yerp. I've been using a nice 12V I found in my garage -- no noise and makes my LEDs run brighter.

[eukatheude]

Started doing the connections on the back. Well, didn't know that was the hard part. The work was coming along very nicely as far as i can tell, i'm afraid this is where it'll get dirty. And i wish i had discovered the trick of not cutting the component legs when you solder them last week instead of tonight. Well, whatever, as long as it works.

[eukatheude]

Two frustrating hours later, i'm not even halfway through. Even left some cold joints i think, but there's no way i'm soldering those points again. Fortunately i have some thin enough shielded wire that allowed me to "cheat" through a couple of tricky spots. You can bet next time i'll etch a pcb or at least use a veroboard.

[eukatheude]

Now, i don't mean to brag, but...

Yep, it looks terrible, and as expected it doesn't work. Really don't feel like troubleshooting now, i might be better off getting a veroboard and starting over.
i am not implying this is anyone's fault but mine, just in case any of the people who helped me, including the layout's author, feel like i'm blaming them

[EricssonB]

Originally Posted by eukatheude

Two frustrating hours later, i'm not even halfway through. Even left some cold joints i think, but there's no way i'm soldering those points again. Fortunately i have some thin enough shielded wire that allowed me to "cheat" through a couple of tricky spots. You can bet next time i'll etch a pcb or at least use a veroboard.

Originally Posted by eukatheude

Started doing the connections on the back. Well, didn't know that was the hard part. The work was coming along very nicely as far as i can tell, i'm afraid this is where it'll get dirty. And i wish i had discovered the trick of not cutting the component legs when you solder them last week instead of tonight. Well, whatever, as long as it works.

Originally Posted by eukatheude

Now, i don't mean to brag, but...

Yep, it looks terrible, and as expected it doesn't work. Really don't feel like troubleshooting now, i might be better off getting a veroboard and starting over.
i am not implying this is anyone's fault but mine, just in case any of the people who helped me, including the layout's author, feel like i'm blaming them

What is your process? What hardware are you using? What sort of boards?

Heck, I'd almost recommend starting up your own thread and linking to it from this one. You could probably get some folks to step-by-step with you.

Pics are always good, too.

Perf boards.

[FunkMetalBass]

Does anyone here etch their own PCBs? I'd be willing to pay for one (I'm really tired of perfboards and my own efforts at etching haven't been successful).

Otherwise, is anybody interested in going in on a shipment of PCBs for this?

EDIT: I went through and put this in ExpressPCB. domdec314 did a great job of minimizing the footprint, so I didn't bother changing it. I also really like the idea of feeding the wire through the board holes to both secure and neaten the layout - it's a nice touch and I left it in.

In its current state, it's 1"x2.5", so if ordered through ExpressPCB, one could reasonably get 3 miniboards with 3 PCBs on each (9 in total) for ~$80 shipped in the U.S. That includes the top and bottom layer + silk screen.



We could maximize our efforts and minimize cost even more by precariously shaving .1" off of the height for each layout to get 4 PCBs per miniboard (12 in total), but that would require much more precision when cutting them apart.



EDIT2: I just saw the posts on the previous page about placing an order for these PCBs. Now I feel like a durn fool.

[eukatheude]

Originally Posted by EricssonB

What is your process? What hardware are you using? What sort of boards?

I populated the perfboard from one side, soldered on the other and cut off all the components' legs. Then i connected them using solid copper wire and, where it was possible, directly with solder. Unfortunately i shifted the layout a bit in order to make the work easier, but it turned out to complicate matters a lot.
I'm using a cheapo iron, i think it's 20W, which is decent but i think the tip is very worn. Still, last week i've used it to change pups and electronics on a friend's guitar and had no trouble. I'm using tin solder, 1% copper and 2% flux.

Heck, I'd almost recommend starting up your own thread and linking to it from this one. You could probably get some folks to step-by-step with you.

Pics are always good, too.

The trouble is that i probably got the "theoric" part right, the problem is that i just connected everything badly. Probably today or tomorrow i'll take a better look at it and start checking every contact. I won't say i'm experienced with soldering, but i think i'm at least decent at it.
I think i'm better off buying again most components and starting again on the other corner of the board. Or i might try making the PCB myself, the sharpie method seems easy enough though i'm not sure where to find the chemicals/how much they cost.

EDIT: I should add, when i plugged it in i had wired in only the volume pot. On my amp i just heard lots and lots of static and SOME signal.

[delta7fred]

Originally Posted by eukatheude

I'm using tin solder, 1% copper and 2% flux.

For a novice I would highly recommend the old fashioned tin/lead 60/40 with rosin cored flux. It is far more forgiving than the new lead free solder.

EDIT: I should add, when i plugged it in i had wired in only the volume pot. On my amp i just heard lots and lots of static and SOME signal.

Not really a fair test trying to run the preamp with components missing. Try it again once you get the tone pots fitted, you may be pleasantly surprised.

[eukatheude]

Originally Posted by delta7fred

For a novice I would highly recommend the old fashioned tin/lead 60/40 with rosin cored flux. It is far more forgiving than the new lead free solder.

Actually i started out using a 50/50, the only one my town's hardware store had, and i'm much much more comfortable with the one i'm using.

Not really a fair test trying to run the preamp with components missing. Try it again once you get the tone pots fitted, you may be pleasantly surprised.

I ran out of wire Maybe i can find some if i dig around the garage.

[eukatheude]

Originally Posted by delta7fred

For a novice I would highly recommend the old fashioned tin/lead 60/40 with rosin cored flux. It is far more forgiving than the new lead free solder.

Actually i started out using a 50/50, the only one my town's hardware store had, and i'm much much more comfortable with the one i'm using.

Not really a fair test trying to run the preamp with components missing. Try it again once you get the tone pots fitted, you may be pleasantly surprised.

I ran out of wire Maybe i can find some if i dig around the garage.

Meanwhile, here's some better pics:





By the way, in most pedal layouts i've seen, usually there's a ground wire going to the jacks. From where should i connect it?