Phase 90 Volume Drop

[rasco22862]

Hi, i finished this building from tonepads layout. I notices that when the fx is on, the volume drops. I read in the reports that the last 150k resistors has to be changed to 180k to fix the volume drop,is this right? i mean, do i have to put more resistance or less resistance. I think less
Thanks

[petemoore]

IIRC that's a resistor from output signal path to ground, yes larger resistor will shunt less signal to ground then, and output will get more, a little bit more.
  If the difference to unity volume is great this may indicate something else is causing it.

[rasco22862]

i`m confused is the the resistor between the collector and base of the pnp or is the last resistor between ground and OUT, that i have to change it to 180k??

[MartyMart]

i`m confused is the the resistor between the collector and base of the pnp or is the last resistor between ground and OUT, that i have to change it to 180k??

It's the 150k to ground just before the output, top right of PCB.
Try a 180k/200k and see how that sounds.
Marty.

[rasco22862]

I put a 220k replacing the last 150k and the same little volume drop. Should i change the resistor between the collector and base of the pnp ?
In the tonepad site says "The resistor to change the level is the 150k which connects between the collector and base of the PNP transistor: 120k to reduce gain, 180k to increase it."

Thanks

[rasco22862]

anyone?

[loki]

don`t know if this would help... i have an original one (which i modified anyway to sound like a script version), and there`s a volume drop when i switch it on if it`s the last pedal in the chain before the amp. if i put a buffered pedal after it (right now a DOD FX90 Delay going to the amp), there`s no volume drop at all...
I don`t know, just try that...

[Ptron]

i`m confused is the the resistor between the collector and base of the pnp or is the last resistor between ground and OUT, that i have to change it to 180k??

I think that last resistor is there to reduce switch pop and isn't going to affect the output much until it gets to be a quite a bit lower in value. The resistor between the collector and base of the last transistor provides negative feedback to the base, so increasing it would reduce negeative feedback and increase output, but it looks like it also biases the transistor so it could muck things up a bit. This is a funny arrangement to me, with the emitter at  5V and all, so i'm not completely sure how that would work.

[rasco22862]

what does you think that that resistor bias the transistor? if this is correct, what tonepad sites mean with "The resistor to change the level is the 150k which connects between the collector and base of the PNP transistor: 120k to reduce gain, 180k to increase it."

Thanks

[Ptron]

what does you think that that resistor bias the transistor? if this is correct, what tonepad sites mean with "The resistor to change the level is the 150k which connects between the collector and base of the PNP transistor: 120k to reduce gain, 180k to increase it."

Oh. Well, if they say that then changing the resistor a little bit must not throw the bias out of whack enough to hurt anything. If you change it to a 120k, you get more negative feedback through the resistor and less gain from the stage. If you change it to 180k, the opposite happens.