Phase 90 debugging help needed

[Xavier]

I just built the Phase 90 according to Sabrotone's layout here http://www.sabrotone.com/?attachment_id=222 . It's been done following the Tonepad schematic.

I used matched 2N5952 transistors, so it really sounds good. The only problem I have is that it sounds a bit distorted (both in Script and block mode) on the clean notes, I mean like if you were using a low gain overdrive on top of it. Enough to bother me.....  . I am not able to find anything ,,,,,,,,,,

Here are my voltages in case any kind hearted person is willing to help... thanks in advance !!

V:   9,18
   
   
   
Q1   
D:   4,39
S:   4,39
G:   2,06 - 2,36
   
   
Q2   
D:   4,4
S:   4,4
G:   2,07 - 2,40
   
   
Q3   
D:   4,4
S:   4,4
G:   2,07 - 2,41
   
   
Q4   
D:   4,4
S:   4,4
G:   2,08 - 2,40
   
   
Q5   
C:   2,6
B:   3,82
E:   4,4


IC1:   
Pin 1:   4,4
Pin 2:   4,4
Pin 3:   4,4
Pin 4:   0
Pin 5:   4,4
Pin 6:   4,4
Pin 7:   4,39
Pin 8:   9,19
   
   
IC2:   
Pin 1:   4,4
Pin 2:   4,39
Pin 3:   4,4
Pin 4:   0
Pin 5:   4,4
Pin 6:   4,4
Pin 7:   4,39
Pin 8:   9,19
   
   
IC3:   
Pin 1:   4,4
Pin 2:   4,4
Pin 3:   4,21
Pin 4:   0
Pin 5:   3,6 - 5,36
Pin 6:   3,79 - 5,34
Pin 7:   1,27 - 8,58
Pin 8:   9,19

[thomasha]

check the output transistor,

There is a 150k resistor, you can change it, but you will lose some volume.

I build one of those with solderman's layout and used a different output transistor.

Don't forget to check the first opamp stage, maybe that is causing the distortion.

take a look here:
http://www.electrosmash.com/mxr-phase90
to understand what does what in the pedal,

and you can also make an audio probe:


and follow the signal chain. It will be easier to find where it's distorting.

Thomas

[Xavier]

Thanks for your suggestions .......will do and will post my results here !!

[Xavier]

OK.....

- Subbed the 2N4125 by a 2N3906
- Redid all solder joints
- Triple checked component placement and value.

Still the same... this is on "script mode",,,,,,in "block mode is even worse

Here's a sound sample direct to PC. 1st half dry, 2nd half with the effect on.

https://soundcloud.com/xavier-martinez-6/phase-test

It phases quite nicely, but I have this ugly distortion underneath... I have also noticed some volume boost.

Any idea what could it be ?

[thomasha]

I would say too much gain at the output transistor, or input opamp,
the rest of the circuit just makes the phase thing,
when i first built mine it had a lower output than bypass, i changed the final transistor's resistor and it sounded louder.

Check also the tonepad build report, sometimes there is something about this.