edp wasp filter

[caress]

has anyone ever built this?

schemos here:
http://www.elby-designs.com/wasp/filter.pdf

and jurgen haible's copy with cutoff control;
http://jhaible.heim.at/tonline_stuff/hj_wasp.jpg

i'm having a little trouble getting legit sound...   my multimeter just broke, too     so i can't check voltages...

it's working in a very weird and crapped-out way - obviously not how it SHOULD sound.  so, i checked my traces, power situation, replaced all ics... still the same problem.  i'm using some ca3080's i got in trade from a forum member.  they don't say ca3080 on them, rather they have printed 7-7141 RCA 7941... these are ca3080s, right?  the only other thing i could see being wrong is my regulator being fried, but right before my MM died, i was able to check that and it was working.  go figure.  if anyone can chime in or has built this, it would be some great help...

also, on jh's schem,  bottom right corner, on the cutoff pot, next to the diode to ground is a questionable part?  i assumed a 1k resistor to ground, but i'm not sure.  any ideas?

[Paul Perry (Frostwave)]

I have no experience with this, but I do know that Jurgen's schem works, as many guys on synth-diy have built it from the schem.

[nordine]

would this thing work out of a jrc13700? ..it should, but i'd like to be sure sure

seems pretty straight forward... i recall the wasp as a rude and Crude sounding thing, great for drums and crappy casios 

[caress]

i can't get on the synthdiy forum to search...maybe it's down right now?

[Paul Perry (Frostwave)]

i can't get on the synthdiy forum to search...maybe it's down right now?

http://search.retrosynth.com/synth-diy/index.html
working fine at the moment, for me. I used it to find this, about the mystery resistor:
From the man himself:

"A 'select on test' resistor. You can also use a trimpot.
Just build it without this resistor, and you'll notice that the cutoff won't
go to very low frequencies. (The voltage drop over the diode is larger than
the drop over the OTA's Iabc input structure.) If you completly shortcircuit
the diode, you'll wast much of your logarithmic potentiometer's range.
So just choose what fits right for you.

(Hey, I *said* this was a cheap design (;->) - use a real expo converter,
preferably the one from the original Wasp, if you want "ordinary"
behaviour.) "

[caress]

thanks paul!  big help...

although i'm still not sure about my "ca3080's".  does anyone know if 8 pin metal cans branded 7-7141 RCA 7941 ARE ca3080s?!   

[oskar]

http://dropmix.xs4all.nl/pipermail/synth-diy/2007-September/002851.html

I link what I could find about these IC's. Not a lot that is... 
The rca 3080's I've seen all have ca3080 printed on top. I've never seen the metal can ones though...

I built the one from EDP's drawing and it worked straight away, no poblemo...
Building it around a 13700 shouldn't be a problem to.

skar

[Mark Hammer]

thanks paul!  big help...

although i'm still not sure about my "ca3080's".  does anyone know if 8 pin metal cans branded 7-7141 RCA 7941 ARE ca3080s?!   

Those may actually be 741s.  I know most of yu are used to them being plastic, but there was a time when a great many single op-amps came in metal-can packages.  I have 741s, 301s, 709s, and maybe even some others too.

[Paul Perry (Frostwave)]

although i'm still not sure about my "ca3080's".  does anyone know if 8 pin metal cans branded 7-7141 RCA 7941 ARE ca3080s?!   

Maybe not.
The only way to tell, is to make a small test circuit - some simple 3080 circuit & plug one in.

[RLBJR65]

7-7141 RCA 7941 are RCA house numbers but they are definitely CA3080. When I got the first few I was plenty sceptical myself. The only other marking was hand written on the box cover it said CA3080 family. I tested some in a Ross comp clone before I bought the rest of the lot. Since they have been used in several other pedals by forum members. BTW Steve at SB also has some from the very same lot

[caress]

ok ok...ron said that these fry pretty easily and when i first clipped on power, my battery was putting out something like 11 or 12v and i ended up getting 6 or 7v from my 5v regulator... 
probably fried.  tomorrow i'll pop in 2 new ca3080s and probably a new 4069, use a regulated 9v supply and check it first! to make sure i'm getting 9v, then test it out.  i've got some more ca3080s on the way just in case, but they're just not the same without the metal can mojo... 

[Paul Perry (Frostwave)]

The way to fry a CA3080, is to let the + rail touch pin 5 for a nanosecond or so.
There is a strict 2mA maximum input current rating for pin 5.
Maximum supply voltage for single sided use (like in a stompbox) is +35V, so the 12V wasn't the problem.

[Mark Hammer]

7-7141 RCA 7941 are RCA house numbers but they are definitely CA3080. When I got the first few I was plenty sceptical myself. The only other marking was hand written on the box cover it said CA3080 family. I tested some in a Ross comp clone before I bought the rest of the lot. Since they have been used in several other pedals by forum members. BTW Steve at SB also has some from the very same lot

Ah, the dreaded "house number".  I forget what it's called but there is a master semiconductor reference that lists all known device numbers/prefixes/suffixes including house numbers, using a difficult to follow indexing system.  The last time I looked at one was some 20 years ago, and even then it was massive, printed on very thin paper, and using very tiny print.  I can't begin to imagine what the current equivalent is like.

[caress]

The way to fry a CA3080, is to let the + rail touch pin 5 for a nanosecond or so.
There is a strict 2mA maximum input current rating for pin 5.
Maximum supply voltage for single sided use (like in a stompbox) is +35V, so the 12V wasn't the problem.

hmmm...pin 5 is for the vc connection though...?  so there has to be some voltage going to the pin, right?  maybe i just pushed it a little too hard?

[Paul Perry (Frostwave)]

hmmm...pin 5 is for the vc connection though...?  so there has to be some voltage going to the pin, right?  maybe i just pushed it a little too hard?

it's actually current control, not voltage control.
in practice, you usually have a voltage going to a resistor, which itself connects to pin 5..
To be safe, if your supply voltage goes up to 12V, you would want 6K or more resistance in series with the current control pin 5, to limit the input to 2mA maximum.
And in fact checking jurgen's circuit, there s at least 6.7K in series between the power rail & pin 5!!
So if your 3080s are frying, I think it's more likely a wiring error.....

[caress]

a little update:

i got the wasp filter working!  it sounds great.  a little gritty normally and really nice when overdriven, so i may add a preamp stage to give it that extra grrrowl.  i used some new ca3080e ics instead of the metal cans and it fired up no problem.  is the pinout different?  the little metal tab on mine could either be pin 4 or pin 8 so i figured they were 8...?  hmm...

anyways, a pretty simple perf build if you think about the layout a bit.  i had to do some interesting lead routing...i'll post some pics and soundclips in the next week.  a great 9v filter!

[widdly]

Did you run it straight of 9v or regulate to 5v?

[caress]

i used a 5v regulator (LM78L05)

[caress]

a few further questions about the wasp filter...

i added the jack orman mosfet boost on the input so i could overdrive the filter if neccesary.     it works really well except i'm having 2 little issues.

1.  i'm getting popping even after adding 2.7M resistors from input/output to ground
2.  the effect takes a half second or so to fade in when switched on...must be a cap, but it's working fine and there's only 1 or 2 electro caps in the whole effect.  both oriented correctly...

any ideas?

edit:  forgot to ask if anyone knows a way to eliminate the popping that occurs when switching between filter types.  is that even possible when switching between different audio lines?

[swt]

does this filter self oscillates when resonance is at max?