Messages

If someone were to open an eBay site over there in the Red land and pimp out tested, known good 3005s, 3008s, 3007s, etc. they would make a KILLING!!!

I bet if someone COULD do that, they would. I'm going to guess that testing MN3005s all day (if indeed they have the capacity to properly test them) is not a practical way to run a parts supply business. These guys buy chips from suppliers. Every time there's a step in the supply chain, it's an opportunity for fakes.

Well, the simplest gate would be to make the fuzz itself gate.

The issue is that you want the gate to open with small signals, but also to close with ... slightly smaller signals. Noise gates are so complicated because they have to figure out if you're actually playing. 50cycle (I think that's what you're on) hum is not exactly quieter than a quiet guitar note, so if you make the gate simply look for pure volume, then pickup noise will open it. Buzz can easily be roughly the same volume as a quiet note. A simple gate will sound ... gated, rather than just "no noise when I'm not playing."

Or you can just use a buffer and not worry about all the math. 

The 200K/3 feet math still applies to buffers, it's just that they really simplify the number of moving parts!

My degree is in English (with enough credits for a minor in Russian, but Towson didn't have a Russian or foreign languages program, so no dice), with a focus in research and critical analysis. So I can't give an opinion about getting an EE degree. But I might have something useful for you to take away.

Here are the things I'm most interested in now: Music, electronics, astronomy, politics, books, and food. Here are the jobs I've held for any length of time since I turned 18: Russian linguist, elementary/secondary substitute teacher (and no, I didn't just babysit ... I actually taught the lessons), science editor (for PNAS), music writer/editor (this was volunteer for Driftwood Magazine, but it was basically a second full-time job), and paralegal.

I'm essentially self-taught in everything I do. Despite having a degree in English, the only job I've ever held "in my field," science editing, required far more expertise than my degree trained me for.

What I DID learn is how to learn -- as much as possible, quickly.

I'm not exactly successful in life, and I'm not the best at anything I do. But I muddle along. I have the free time to pursue things I'm interested in. I don't think I'd be a more successful musician if I'd studied music. I don't think I coulda been a rocket scientist. I would have hated being a cook. I originally wanted to go to college for Archaeology, but obviously I couldn't be further from that.

So I would say: Study what you really love, but get everything you can out of learning now. That's the real skill you'll learn from college.

Unless you want to get paid. In which case, learn a science.

Hotone?  When will a competitor start up named "pimptone?"

I can see it now. People start cloning these they'll call em slutone. Because they do it for free.

I like where this thread went, and quickly.

Probably worth revisiting this post now that I know a bit more about this stuff.

I went back to my original Zen Drive clone and added an input buffer (with buffered bypass!). I'm going to say that I'd never build the thing again without a buffer. I don't think it reacted much like an amp at all as far as the input loading goes, though I get that the distortion, and not the "clean" settings, were meant to be an amp imitation.

The op amps used in the Zen are BJT-based. BJTs just in general don't have good input impedance. This is compounded when you're using the input stage to also serve as a gain and distortion stage. I know that the Son of the Screamer and similar designs are battle tested and that some people like them, but to me this method just makes the guitar sound muffled and behave erratically.

@ Forrest: One good way to think of total input impedance calculations is to take into account average cable lengths. I'll refer to PRR's post in this thread:
http://www.diystompboxes.com/smfforum/index.php?topic=105399.0

Everyone should at least look at that thread for a second, because PRR's post contains one of the most awesome graphics I've ever seen.

Anyway, this is what he said:

Two 2Meg inputs (1Meg mono) ought to be plenty gentle for any signal on a wire. (Three feet of cable is 100pFd which is under 200K at the top of the guitar band.

This was really useful for actually visualizing a real-world consequence of input impedance. A decent rule of thumb to derive from this would be 200K for every three feet of cable you expect someone to be using before you start cutting into frequencies produced by the guitar (realistically, that's about ~15KHz; most adults can't hear above 17Khz at all).

Keep in mind, though, that BJTs and FETs have different input impedance characteristics, especially when it comes to source/emitter vs. collector/drain (voltage gain) followers. Also, MOSFETs make essentially perfect single-stage drain followers with super low input and output impedances (better than even FET input op amps, imo), but make crappy source followers.

Cant remember the name of the company but I saw recently (on youtube) they were offering effects inside those half size 1590b enclosures.  If there was a control, it would be on the inside as a trimpot.  As far as I'm concerned that's the point where small size hinders the functionality of the pedal and its time to look at the next size up. 

Also, stompboxes are meant to be stomped....you know...its a pretty small target...

It's Henrietta Engineering. And they're designed to be one-trick ponies, variations of effects that were only one knob anyway. How often do you really change the volume on an orange squeezer in a playing situation? The originals had no external controls either. I actually kind of like his schtick. Remember that not everyone's a knob twister.

I'll try out the transistor method, but why does that invert the phase? If using a pair of 2N3904/6, don't they have the same turn on voltages, so they'd open up the C-E juntion at the same time?

Another question - what exactly 'turns on' the transistor? The input voltage or the current? Can you parellel multiple strings of transistor's this way / what is the limiting factor here?

Finally, what about the depth control? is it possible to tap the CV out of the lug2 of the depth pot?

The Lune's LFO controls an LED. If you're inverting the phase of it, it's because you need the control voltage to turn on two LEDs in opposition. That's what the transistors will do. The potential of the LFO's CV will determine which "direction" the transistors will pull current when the voltage swings in a certain direction.

I'd breadboard this first, obviously. For one thing I'm not sure if you need to decouple the LFO output.

The limiting factor is the drive of the OP amp, I'm pretty sure. There's an upper limit to how many things you could drive, and there will be some loss with each transistor, I think. (But the transistors also help prevent ticking in the unlikely situation it appears, so there's that.)

There's another way you can do it: you can feed the output of the op amp to a complementary pair of transistors (an NPN and PNP). I used this method recently to convert a CV to out of phase LED drivers and I found it to be simpler than trying to do it with an op amp, but then I'm not very good at tinkering with op amps.

I'll see if I can remember an example of it with the Lune's LFO.

Essentially, you'd hook up the CV output (that's pin 7 of the op amp) to the bases of the complementary pair, put a small resistor (~470R-1K should be fine) between the transistor and a power rail (I think doesn't really matter which), and the LED between the transistor and the other power rail.

       9v
        |
        LED
        |
        C
CV > B
        E
        |
       1K
        |
        G

Note that you will get better performance if you can actually match the transistors and use 1% metal film resistors for the CLR.

I swear you can hear the difference with logic pro, it sounds cleaner than garageband and I think it's easier to use than cubase.

It's not just cleaner, there's a higher signal:noise ratio (this was the biggest thing I noticed right away), and less compression (even with the compressors off in Garageband, it still has a little bit of stickiness on the basic track).

Excellent and most beautiful!!! What on/on/on toggle is it to use here, I believe there's two different varieties that contect the lugs somewhat differently, is it this one from Smallbear http://www.smallbearelec.com/servlet/Detail?no=900 ? Thanks!

That's the correct switch.

Picked up LogicPro today ...

Holy crap, what a difference. I didn't finish a recording in it yet, but it's amazing how much better it sounds.

I think I'll stick with the Logic amp plugins for now, but thanks everyone for the plugin software suggestions ... if I start getting more useful stuff out of this, I might upgrade to some nicer plugins.

Is there a resistor there to, like a "feedback" resistor?

There is, but it goes to Vb in this particular pedal, rather than the collector. Not sure if the calculation is the same. I'll check on Electrosmash, thanks.

So if I jump the 9V to IC3 Pin1 I should be in business?

Yes. But you might want to solder it to one of the resistors instead. Less chance of damage.

I've had trouble even searching for this information, because I don't know the technical term for these things. It's the little bypass caps between the base and collector (or gate/drain). Same sort of thing that's in op amp feedback loops to "cut" treble.