The Hyper Flanger: modded Boss BF2 Flanger

[Gila_Crisis]

so, since i managed to find those 3PDT stompswitches, i decides to true-bypass my mighty Boss BF2.
since doing this I just decides to mod a little bit the pedal. here you go:
- changed IC1 and IC2 with two TL072
- removed the flip-flop circuit and true bypassed the pedal
- vibrato switch: lift one end of R28, so that the dry sound is taken out and only the wet sound is left (switch top right)
- LFO waveform switch: select the wave shape of the LFO triangle (original) or square (switch left down, more info about this mod here http://www.geocities.com/doctor_110/BF2MOD.html )
- speed range switch: i changed C27 and C28 with 2 pair of electrolitics caps, two 4,7uF on one side of the switch and a pair of 47uF on the other side (switch top left)

Then i change those componets as well:
R29 20K
C1 100nF
C3 10nF
C6 33nF
C7 3.9nF
C8 2.2nF
C9 1nF
C17 and C20 i changed the elcos with a pair of 220nF non polarized caps
C21 27nF
C22 180pF
C24 4.7uF
C30 68pF

lastly i played a bit with the trims inside the pedal and well of coarse for a touch of stile i changed the red led with a blue one 

here you'll find some more infos about some of the mods i've done: http://www.diystompboxes.com/smfforum/index.php?topic=34677.0

here's a pair of sound samples:
http://media.putfile.com/flangermod1
http://media.putfile.com/flangermod2

and some pics of course ^_^

[kurtlives]

Is there a standard method for true bypassing Boss pedals?

[sshrugg]

Is there a standard method for true bypassing Boss pedals?

From what I understand, adding true bypass to boss pedals is pretty much the same procedure from one to the next.

Gila Crisis just added other (excellent) mods to make the sound a little prettier : )

The LFO waveform and vibrato switches are my two favorite additions.  Excellent work!

[i2k]

Hi Gila_crisis,
I have several questions about the mod before doing it myself :

• After replaced IC1 & IC2 does the sound get brighter (due to the use of JFET input buffer on TL072) ?
• Looking at the schematic, is it really necessary to remove all flip-flop components (i.e: Q9 & Q10) to make it true bypass ? I think that bypass Q4 is enough and then wire the board's input & output to 3PDT. Pls correct me if I'm wrong.

thanks...

[George Giblet]

One thing you might not realize with this mod is you have changed C3 (pre-emphasis) without changing C23 (de-emphasis).  This means the pre-emphasis and de-emphasis don't match so when the effect is in bypass mode you end-up with a midrange boost of about 2.3dB at 800Hz.

In effect mode the midrange boost is also present.  If you made C23 match C3 you will flatten the response in bypass mode, but you also flatten remove the boost in effect mode, which you might not want.  To get the midrange boost in effects mode only you will need to change C8 and C5 then add an extra R and C.   

Alternatively one could argue that the midrange boost could be added in the amp if desired and that the effect should be left flat with C3 unchanged.