Building a treble booster

[Dom]

A treble booster has been on my need to have list for some time now. To celebrate not loosing my hearing to a recent ear infection I'm finally building one. The circuits for the rangemaster or even the op amp versions of a treble booster are simple and cheap. I really can't justify paying any money for something I can build myself for less than 50 bucks, especially if I can add a few bonus mods to the mix. I'm building an op amp treble booster with an LM741 chip, not to get in a silicon vs germanium but I'm looking for a low noise, low cost solution.That said, I'm adding some tone shaping mods to the basic plan.

Starting off I'm building it in an old Crybaby that long ago bit the dust. I'm going to use the expression pot as a volume, just like using the guitar's volume knob for clean to dirty sounds. Push the pedal down to engage the circuit or bypass. With the pedal down the volume is at a bare minimum for clean tones. Rock the pedal back and the volume increases for driven boost. If I don't like that it is simple enough to wire it the other way. I'm adding a switch to bypass this volume function for just boost. There is a gain knob. I'm adding a rotary notch filter so I can choose between several cap values and a tone pot off that so I can dial in the amount of filter I want. I'm also going to add an inductor with a center off toggle switch so I can bypass or choose either half or full coil of the inductor for a notched wha sound. I'm on the fence about adding a diode clipping circuit at the end for added grit with a pot with an off switch. If I do I'll have a tone shaper/booster/volume/distortion pedal.

I'll let you all know how it turns out. Now back to my soldering iron. Cheers!

[kiramdear]

Well, you sure sound like you know what you're doing. I wish I was functional with electronics. So I'll stay tuned and maybe learn something. Success!

[Dom]

Honestly, I never completely know what I'm doing! Nothing I've done as far as electronics goes has been too complex or expensive and unlike with a tube amp, 9 volts can't kill you. Like with my 350 resto, everything is just a learning curve. The internet is the greatest 101 class ever.

Fortunately there is a huge wealth of knowledge on the web for DIY amps & effects, even more so than guitar wiring. The Craig Anderton book Electronic Projects for Musicians is a good basic intro and Runoffgroove.com is a great place to start for free schematics such as the 9v powered Ruby amp which can even power four 12's that you can build with parts from Radio Shack. The rest is learning the component symbols & values, researching what you want out of an effect, seeing what works for everyone else & following a schematic. The real art is in soldering & wiring them up cleanly & economically.

I'm really only adding passive effects & a couple on off switches to an existing design. The notch filter-inductor/varitone circuit, volume and diode clipping circuit is really simple. I made one in a radio shack box (which is great for learning what tone caps you like) but they could all be thrown into a guitar just as well. That said one of the reasons a treble booster works so well is that it is such a simple circuit so I'm adding things that require no power to function. They just have to be put in the right place in the signal chain to work.

I'm possibly taking a stompbox building class at Stanford in August to build effects with an Arduino that you program with a computer and open source programming language. The idea of programming a circuit to do whatever you want is tantalizing but it is completely foreign territory to me.

[cjj]

Sounds like a cool project! Can you post a schematic (or post a link)?

Personally, I'd go with something better than a LM741. Those aren't really great for audio, not particularly low noise and pretty slow (0.5V/uS) for fast transients. The OPA132/2132/4132 are still fairly cheap but much faster (20V/uS), far lower input bias current (50pA vs. 80nA) for less offset error, super low noise and distortion...

[jps]

How do LM833 compare?

[cjj]

How do LM833 compare?

A bit lower noise (4.5 vs. 8 nV/√Hz), more distortion (0.002% vs. 0.00008%) Slower (5V/uS vs. 20V/uS). Probably a decent op amp if you don't push it.

The TI/Burr-Brown OPA132 series are optimised for Audio applications, which makes 'em pretty dang good for use in audio equipment...

[Dom]

Sounds like a cool project! Can you post a schematic (or post a link)?

Personally, I'd go with something better than a LM741. Those aren't really great for audio, not particularly low noise and pretty slow (0.5V/uS) for fast transients. The OPA132/2132/4132 are still fairly cheap but much faster (20V/uS), far lower input bias current (50pA vs. 80nA) for less offset error, super low noise and distortion...

I may give the OPA132 etc. a try. I had was looking for better alternatives to the 741 actually but the only ones mouser had on my list were the 741's. It's basically the Craig Anderton booster combined with the passive tone control (varitone) from his book which hasn't been updated ever. I changed the cap values on the tone control to suit my liking. If this one doesn't do it for me I may just stick in a rangemaster clone & go from there. I do like the idea of a volume pedal added to a treble booster though as only a couple of my guitars still have master volumes now.

Booster: http://img374.imageshack.us/img374/1313 ... ostwr4.gif
Tone control: http://i86.photobucket.com/albums/k99/j ... vetone.jpg

As far as mods I'm using the same 100k from the wah for the volume pot with a bypass switch and wiring it in before the circuit's input. I'm sending the lead to C3 to the varitone so I can have the cap selections or roll them off with the tone knob. I put a on off on DPDT in for selecting 1 both or no coils of the inductor, I'm calling that the "snark" switch. The diode clipping circuit I may just add right before the output jack...either 2 5mm yellow LED's or 2 1N4001's off a spst switch & wired in opposition + to - right to ground. If it sounds alright off just a SPST switch I'll add a pot to vary that circuit too...if not then I'm leaving well enough alone.

[Dom]

I've decided to give an Alembic Stratoblaster circuit a go. It is a super small treble boost circuit that can fit in a guitar. Actually they were designed to fit in the jack cavity of a strat. I built a fuzz over the weekend called a bazz fuss, also small enough to fit in a guitar. I'm going to test them out with some other ideas in the 330 that I'm going to pull the neck from for my custom 350.

[Dom]

Ok, so why doesn't everyone have a booster? Secret ingredient anyone? Seriously, notes just leap out of the guitar with these things. And sustain? Oh man. I now have to make up for all the lost time I spent without one.

So I built the basic stratoblaster in a wha enclosure & now am looking at how to mod it. After playing it a while I decided that the wha's expression pedal will now be working the gain knob instead of an input volume. This will give me the sparkly clean to super driven sound I'm looking for with a nice linear sweep. I'll be adding that Anderton passive tone circuit (varitone) I made so I can use the rotary to choose the frequency I want to boost. One notch of the rotary is a bypass. It has a switch to change from the full coil of the inductor to half. This gives me 10 frequencies to choose from. WIth a switch to bypass the inductor completely that's 15. There is also a tone control so I can roll the filter on or off with my foot anytime I want. The goal is to be able to use it as a passive tone control, booster or both. Not bad for about $25 in parts.