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This one was definitely done solely for the challenge:


I don't use reverb pedals on my board, and fitting a belton brick on perf inside the 1590A was just way too much work.

First, dial down the decay and see if that helps. If it doesn't, make sure you've used the right value for the hold cap (C6).

R15 is a limit into the envelope section. You can increase that -- I'd use a socket until you find a good value, but i suspect 68K will be sufficient (figuring 7 on the guitar = 50% signal, so I'm halving the signal allowed into the envelope by increasing R15 by ~50% of the filter pot's value).

Finally, R1 and R2 form a voltage divider at the input. You could replace R2 with a 100K pot and have an input gain control. Not as preferable due to messing with your output, too, but it would mimic the effect of turning down your guitar.

Good god that's a lot of effort for a crappy implementation. Hacksawing pots? Filing the shafts to make the knob fit properly?

WTF. Just carry usable parts, Radio Shack!

Isn't a tant supposed to be orientated correctly as wel?

They don't blow up as easily.

Sometimes.

Need to know the supply voltages and voltages on the pins of each chip.

If the op amp is on a split rail (suspected due to the op amp specifying "V-" instead of "ground"), then the output will be 0v, but the THAT chip could be running at a different voltage. What's the rest of the schematic?

Thanks for the link. I saw it at some point but didn't really take a very close look.

The method is similar to what's used in the Diamond, where the optocoupler serves as one leg of a voltage divider.

Both of these examples need an input buffer (if not amplifier) to work well with a guitar, otherwise there will be a lot of input loading. There are also some notable tone changes that come about when using the voltage divider method. One is that high frequencies are attenuated more severely than in a variable gain circuit (like the Afterlife), same as turning down a volume control. The benefit is that it's usually a little quieter as long as the actual amplifier is quiet, because it kills line noise pretty effectively (but the signal:noise ratio is still a concern, because after all at idle it's like havign a volume control at half way).

One thing to remember here, despite having all five controls, is that optical compressors are always limited by the performance of the device in a way that FETs aren't.

The Circuit Salad optofet compressor (there's a thread here) is similar in design (one leg of a voltage divider) but uses a much faster optocoupler and has a wider range of controls (especially shorter attack/turn-on time) available.

Would a slide switch work for you?

I did find a four-pole slide switch at mouser, but square holes and round pegs or something like that, you know?

[wool]

where my shaggy beast resides

Nah, that's just the highest quality wool veneer.

The only one that Smallbear carries is the right one, and Slacker over on DIY said he hasn't come across one that worked differently. Do you remember where you saw the wrong ones so they can be avoided?

Sweet! That was fast. Did you etch the case over night, or were you saving it for something?

Weird quirk for needing a fully-counterclockwise volume pot to be 'mute'

Because the pedal is HOLY CRAP LOUD. I was running into situations where 7:30 was unity.

Question, though: Is the PCB upside down because it had to fit in front of the jacks, or did I somehow mess up something with the board-mounted pots? (pleeeease tell me it wasn't that!)

Thanks for the compliment about the sound, too. I fixed mine yesterday as well and I'm now considering moving it to the pedalboard for a bit.

DIYSB to the rescue. Looks like DPDT on/on/on switches don't connect all six lugs in the center.

http://i269.photobucket.com/albums/jj50/walterw2/sp3t.gif

Here's the thread over there: http://www.diystompboxes.com/smfforum/index.php?topic=105180.0

I've discussed it with some people before. I also think there might have been a thread about running two Afterlifes in parallel.

There are two main challenges:

1) Sufficiently isolating the audio bands. This means that when you compress a particular frequency, it gets compressed while the other frequencies are left alone.

2) Sufficiently isolating the envelope bands. For instance, if you play a note with bass content, will it only trigger compression in the bass audio band?

There isn't really a GOOD simple way to do it. For instance, I thought about making a Bearhug with two envelope paths, connected to two different source bypass caps. I ditched the idea because I couldn't isolate the crossover frequencies enough in either the audio or envelope circuits.

The other option is simply to use switchable a treble bypass. (Like in the Engineer's Thumb.) You lose the ability to compress just the treble frequencies, but I think that usually people want the opposite.

EQ circuits have decent isolation, but it's still not as isolated as you'd really want. However, I can think of a really good tool for the job: An 8th order filter chip. They're still available in through-hole chips and would be able to provide the steepest possible cutoff frequency to split a bass and treble band. From there you just have to deal with frequency cancellations in the summing to avoid a dip in the midrange, but that's been discussed to death in mixer circuits.

This would NOT be a small compressor, but I think it could be done in a 1590BB without too many bells and whistles.

EDIT: You could add an adjustable frequency control to the envelope section on a host of compressors. Link to a schematic for a compressor you like and I could make a suggestion.

I need a switch with three independent throws and a single common connection (to ground).

Asci circuitlet:

|----------|           |
Cap 1  Cap 2    Other thing
|           |            |
   \           \            \

                 |
      G (common connection)

Cap 1 and cap 2 must be disconnected when the other thing is grounded (though they could both be in the circuit together if needed, either in series or in parallel), so I can't use a SPDT center off.

Anyone come across such a thing?

I may have seen a slide switch that had four lugs on it, but I can't remember where. Twould be perfect if there was a toggle like that.

x-posted from DIYSB. I'll update if I hear anything there ...

Red Llama comes to mind. Really anything with that chip.

Anything with an OTA chip in the audio path.

Need this thing:

http://www.smallbearelec.com/servlet/Detail?no=1041

But I'm still having a hard time wrapping my brain around it.