Cosmichorus question

[Tubbs]

just got my Cosmichorus straight from Cananda today and i l.o.v.e. love it!

minor problem........i have a Durham sex drive before it and it's clipping with very little boost from the Durham.

(i have a tremolessence after the Durham and it's got headroom for days)

has anyone else experieced this with the Cosmichorus?


suggestions?

thanks!

[Ryan]

Hey Phillip,

The Cosmichorus uses the NOS Panasonic MN3007 BBD chips and they just don't have great headroom.. they're designed for a low level input and it doesn't take much signal to get them to clip. I set CCs up using a guitar with EMG pickups and they'll clip the circuit fairly easily, although single coil pickups will never clip it.

Sending it the output from a boost/overdrive pedal is just begging for clipping though, it'll be hard to avoid. Two things to try, make sure the level knob on the CC is set as low as you possibly can get away with. Second, there's a trimpot inside the pedal that biases the delay line.. I set it where I think is the best sound/most headroom and then I put a dab of hot glue on it to hold it in place. You could try adjusting that trim for yourself, you might find a sweeter position with your setup.

Otherwise, it's just the same old story with that kind of BBD chip... cool sound but doesn't love a hot signal.

PS - Sorry to hear you're having a problem with it! We could try an input pad trimpot maybe, if you like, although I feel those unavoidably change the tone.

[Tubbs]

ok, that makes sense.

looks like the easiest solution is to just put the boost after the Cosmichorus.........fixed!

thanks for the reply Ryan, i love the sound/look!

[Eric!]

So this...means it doesn't really take dirt well?

And since I rock an L2000 at pretty much full-blast all the time..

[Toonster]

chorus before dirt is also awesome

[Eric!]

chorus before dirt is also awesome

[Ryan]

The Cosmichorus is fine with dirt as long as it's not way louder than the bypassed signal... it doesn't like a boosted or very hot signal, just like most modulation/filter pedals. I don't consider it a design flaw or a problem, it's just normal, and the pedal can easily accept the signal from all but the highest output guitars. You can clip any pedal that runs off 9VDC with a hot enough signal after all.

One thing a person who felt their Cosmichorus clipped too early could try would be running it at 12VDC, a few extra volts head room might make a nice difference and the pedal should be filtered well enough to use a non-regulated supply.

[Tubbs]

Ryan, can i feed it 18v or is that too much?

[Eric!]

I think I'll get along with it just fine

[Ryan]

Ryan, can i feed it 18v or is that too much?

Yep, you're safe to try 18VDC, I never have though... let me know what you think!

Maybe some kind of limiter needs to be pondered for the ultimate Cosmichorus one day... I don't like to hear about it clipping, clipping bothers me.. and it is nice for a pedal to be able to handle any signal you throw at it.

[Eric!]

HA, I'm blasting it with 18 volts :D

Why not 24?

[Ryan]

HA, I'm blasting it with 18 volts :D

Why not 24?

The electrolytic caps are the lowest rated at 25V... not recommended but since I'm such a badass I'd probably try a 24V supply, once. *Aerosmith song* Living on the edge!

[Tubbs]

ok, plugged in 18v and no chorus effect came through at all.

the light lit and everything but only a dry signal.

as i turned the mix knob up the guitar signal dropped out entirely.

i don't have a 12v supply so i'll let you know what happens when i get one.

for now i'll just keep all boost after the Cosmichorus.

no biggie!

[Ryan]

Woooops, I left out a really important thing... with a different power supply voltage you'll have to re-bias the delay line. It's easy though: set your mix fully wet, volume about 50%, pick off the dab of hot glue holding the trim pot in place and then hit your guitar strings while you twiddle the trim pot until the signal comes back and dial it in for the cleanest signal possible. It'll need a different setting for 9V, 12V, and 18V, presumably, although I've not experimented with it myself.

(You can do this much more precisely by running a sine wave into the input and adjusting the output while viewing it on an oscilloscope, depending on how well your electronics shop is set up.. if your shop is just a screw driver then that'll work fine too.)

Sorry for leaving that re-biasing info out! *smacks forehead*

[Tubbs]

ok, cool.

i'm a little apprehensive messing with the trim pot.

i fear never being able to get it back to where it was if it doesn't work out.

don't own an oscilloscope. use to..damn!