Messages

It depends on what I'm doing. Last year, I built a lot fewer pedals than the year before, but I think it's because I spent more time on the breadboard and doing layouts ... plus fixing or upgrading some of my older builds.

Right now I'm probably averaging two builds a month, perhaps half of which are for me.

Unfortunately, to get into the class, you have to be able to pick up the lightsaber from across the room and bring it to your hand with the force.

So far Silent Bob is signed up, but they're short on students.

I've used a little gizmo like this: http://www.sweetwater.com/store/detail/LittleIMP/  to convert a balanced xlr mic cable to an unbalanced 1/4" plug.  It's very simple and inexpensive.  I don't recall if I ever plugged it directly into guitar pedals though.  You may need a preamp in there first.  I can check it out when I get home if you like.  Otherwise, effects send/return on your mixer or amp should work.

This is the right way. It's tough to build something like this cheaper, too. Sure also has one.

The second octave down will sound quieter. Part of it is how our ears work -- a very low-octave signal of the same amplitude will sound much quieter than one in a higher octave.

The "jumping" is what happens as your signal dips below the threshold of the rectifier that creates the octave (all the octaves are created with essentially envelope signals). Basically, it's a form of gating. You can replace the diodes in the octave generation sections with something with lower forward voltage -- schottky diodes are good -- and you may get slightly better tracking ... sometimes. You can also boost the input signal, but that may result in some distortion. I've tried boosting the front end of the whole effect (the first op amp feedback loop), but that introduced distortion, too.

All that said ... there are two ways to make the second octave down louder if you are willing to rework some things.

1) There is a limiting resistor at the output of the second octave down, just before the potentiometer that serves as its volume control. You can lower that resistor and increase the maximum final amplitude of the second octave down without affecting much else. The overall effect is small, but it might help some.

2) You can boost the output of the entire effect. Just increase the 10K resistor in the feedback loop of the last op amp before the output. I think I went with 22K on the last one I built, but you can go about as high as 33K before you start overdriving it. The price is that the other octaves become a little bit fussy to dial in, so you'd actually want to use log taper pots for the whole thing.

Go through the schematic carefully. It's a beast of an effect, but the audio paths are actually fairly linear. It's easiest to work backwards from any given control to follow the effect.

Try audio probing, following the first octave down path. I suspect a bad connection somewhere AFTER the first octave is split off from the octave generation, like a dry solder joint on a pot or something.

So it goes. He held on longer than many can.

It's a power transistor. They typically don't have very high gain but they can take a lot more voltage than the more common types we use in pedals. You could give it a shot ... just use a socket.

PM me your address, I'll give you one.

The way I handle these is I use two pairs of pliers -- a needlenose to hold a leg as close to the glass as possible, and a second to bend the lead. Then I make a little double bend:
  ____
|      |
  |    |

Yeah I noticed the price is similar, and since I have to get a few things from smallbear anyways I'll get them there.

I've been tossing in 10 FETs of the three most common types I use (2N5457, MPF102, and J201) into my orders from them, building up a tiny stash slowly without feeling too much of a hit. You might also pick up some 2N3819 while you're there -- those were ROG's suggestion for input buffers, but beware that the pin is different.

Actually, since the Tayda ones aren't usually real J201s (or just very out-of-spec), they might work BETTER.

The J201 in the Harbinger is an input buffer, and it's a source follower. A FET will create clipping as soon as a signal exceeds its Vp (for how to actually measure that value on any FET, check here: http://runoffgroove.com/fetzervalve.html#11); you can observe this by measuring the source voltage on the FET. Plug in one with low Vp and you'll have a low source voltage even with a big resistor (10K is fairly large), but plug in one with a higher Vp and you'll get a higher source voltage. The higher source voltage corresponds with extra headroom.

One thing you can keep in mind is: IN general, the more gain a FET is capable of producing, the lower the Vp will be, and the easier it will be to clip the FET. J201s are pretty much the top of the gain range for FETs.

I use MPF102 for my input source followers when I don't want clipping; they're not very expensive, they have the right pin out, and they're not hard to get ahold of. The source voltage on them with a 10K will be about 3-3.5V, which is pretty high. (In fact, I haven't been able to get higher even with other FETs.)

However, I'm going to suggest you get your FETs from a better dealer regardless, simply because you'll be able to use them in other effects where it matters more without wondering whether they're actually suited to the purpose. It's not like Tayda's cheaper than anyone for their FETs anyway ... they cost as much as Smallbear. It kind of takes some balls to price known unreliable/out-of-spec FETs like that.

Phew.. just finished my card table.


Win!

This is amazing.

Edit: Serious addition. A lot of people keep talking about going it alone etc. being part of the problem. I completely agree, and one of the best TED Talks ever talked about how the one thing all highly successful companies have in common is that they're partnerships:
http://www.ted.com/talks/ernesto_sirolli_want_to_help_someone_shut_up_and_listen.html

Think about those jumpers you've got connecting the three lugs. What's connected when the internal green wire is connected to outside pole 1?

Cool build! What's the graphic?

I guess I'm misunderstand the discussion. I thought everyone was saying that other than output volume, there is no difference between any type of diode clipping in any circumstance.

I don't recall ever looking at diodes to change op amp gain.

I think I'm communicating this badly, but I don't know how else to explain it.

Anyway, I think the op's solution needs some sort of resistor in series with the volume pot on the clipping switch, or to mess around with the 100K on the output.

Are you also correcting for gain differences? Are you saying that LEDs would be different from silicon diodes when the ratio of gain:Fv is the same?

All I'm saying is that if I match the volume output between LEDs and 1N914s in a Rat, it seems to me that the silicon diodes produce more sustain and compression.

I haven't tested on a scope or done any math or read an RG Keen articles on the topic. So maybe I'm fooling myself.

You're not fooling yourself, but output volume is post-clipping. Gain is pre-clipping. As long as your amp isn't out of headroom, LEDs will have a larger maximum volume (but a lower maximum amount of clipping).