phase 45 and rebote delay issues...

[idlefaction]

hey all

i've had this phase 45 for a while built that i'm not happy with.  it phases, but it doesn't sound like it's phasing very much.  is this normal for a phase 45?  the sample on runoffgroove sounds way more pronounced...

http://b.wadda.org/tmp/roger_lame.ogg

sorry it's an ogg, i down have an mp3 encoder handy atm.

also i have just finished up a rebote delay from tonepad.com, it sounds ultra crusty when you get the delay time up!  has anyone got any advice on amounts to change filter caps by in this circuit?  maybe it just has too long a delay at the long end.  heres a sample, you can hear that the shorter delays sound fine but the longer ones sound awful.

http://b.wadda.org/tmp/jake_crusty.ogg

any advice appreciated...  

[nightingale]

man!
that stinks... both of those circuits are on my "build next" list... i play a phase 90, but it's not true bypass... that sorta irks me... so i was gonna build the phase 45 clone... i also thought the sound sample at runoff had enough phase for me...

and i play a couple delays in a row... one analog, one digi... i planned on replacing my digi delay with the rebote 2 from tonepad...

i will keep a close eye on this thread... i  hope you get the bugs worked out of those circuits... i wish i could be more help

[J. Luja]

did you match the fets in the phase45?
and which version of the rebote did you build?

[idlefaction]

yeah, the fets were matched really closely using both of the common matching circuits, i forgot whose they are (sorry!)  i had 24 pcs and had them matched to within 0.005V at 10k and i forget how close at 470k.  closer than necessary though.

i might try a feedback mod, or maybe even matching the capacitors as well.

with the rebote, i built the rebote 1.  i suspect that the chip just isn't supposed to have that long a delay!!!!  will post my findings  

[J. Luja]

well, feedback creates resonant peaks in between the notches of a phaser, so it doesn't realy work with a "single notch" phaser like the 45. matching the caps won't make a difference either I'm afraid

take a look at the rebote2 and try changing the components surrounding the delay chip to match those, the rebote1 used the app note suggested values which set the anti-alias filter at something like 10kHz which is a bit optimistic for this chip

[idlefaction]

matching the caps will make a difference, you must have misunderstood, i was meaning the two caps that determine the cutoff frequency.  if i'm matching Vgs to within 0.1%, kinda seems silly to be using 10% tolerance caps!!  

how would i go about matching capacitors?  the caps i buy are 'K' or 10% tolerance, i guess thats the tradeoff because they are so small...

[idlefaction]

awesome, i had a look at those cap values for the rebote 2 and yeah they drop the filter frequency to about 4-5k instead of 10k.

i put in the different LP filter caps though and there's still loads of crud present at higher settings - i think i will change the 50k pot out for a 10k pot and 10k resistor switchable in/out.  i don't need all that delay time anyway, it's just for atmospherics rather than repeats.  

[J. Luja]

matching those caps can make a slight difference, but even more important would be matching the 10k resistors in the all pass and mixing stages.
matched caps seem to make a sharper notch but I can't even "see" a difference until they're mismatched by more than 200% much less hear a difference