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Re: Boss CE-1.....................True Bypass?

1/18/2001 5:17 PM
Jay Doyle
Re: Boss CE-1.....................True Bypass?
Well, I looked and you are right, this isn't the  
same switching scheme as used in the later  
Boss/Ibanez pedals. It is the same concept, just  
a different implementation.  
The input impedence is set by the input buffer,  
which is used to drive the output, either clean or  
effected. The normal/effect switch changes the  
on/off state of two FET's whose drain/source  
channels are in series with the outputs of the  
effect circuitry and the input buffer. When one is  
on the other is off, thereby deciding which path  
is selected, either the effected signal or the  
signal out of the buffer.  
First off, the buffer is set up poorly. The input  
signal goes through a 50k pot set up as a  
voltage divider, through a 10k resistor in series  
with the + input of the op amp. This sets the input  
impedence as the parallel value of the two arms  
of the voltage divider in parallel with the 10k  
resistor. This is going to be less than 10k which  
is enough to load your guitar significantly.  
There is a bunch of stuff you can do to fix it, sort  
of. If you dont use the input level control or don't  
mind it being on full all the time, replace the pot  
with a 470k - 1M resistor to ground, take the  
output off of the top of the resistor and directly  
into the + input of the op amp, jumpering the 10k  
in series with the input. This will help but won't fix  
your problem completely, we haven't even talked  
about what happens when you use the mic  
preamp, same idea only it looks like it would  
load the signal even worse. There is a lot of stuff  
going on to your signal, "normal" or effected.  
For that reason I would suggest simply building  
a true bypass box for you to switch this effect in  
and out. You just leave your CE-1 on all the time  
and bypass it with the true bypass box; you  
could even buffer the input of the effect with the  
true bypass box to minimize the loading effects  
when the effect is on. Much less trouble and  
doesn't risk a vintage effect selling for $200 and  
up. Not that that really matters, it's your effect. I  
would especially suggest this if you don't have  
much experience tinkering with effects, there are  
some sensitive chips in there. Not to mention  
this is one BITCH of a circuit and would be  
extremely difficult to navigate around the circuit  
Save your time, build the true bypass box in  
about less than an hour and build the Shaka III or  
the Booster 2.5/Sweet Thing with the time and  
frustration you saved.  
Hope this helps.  
Jay Doyle

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