Madbean phase 45 stalled again...

[Luke51411]

So this is the second time I don't have something in my inventory to complete the build. How important is the value of r19, I don't have a 3m9 resistor can I replace it with something else? Also I have the tayda 2n5457 fets of which I have found a matched pair. Should these work? I know I've heard of issues with fets from tayda before. Thanks for the help.

[vigilante397]

I've never had any issues with FETs (or anything else for that matter) from Tayda, but when you don't feel confident about a component then make sure to socket it in case it doesn't work out.

As for the resistor, when I don't have access to a part my first choice is always something within the 10% tolerance range, and if I can't find anything there then my second choice is running multiple components together. In this case you would need to run multiple lower-value resistors together to add up to 3.9 M or thereabouts. This could be a pair of 1.9M, 2M, etc. or four 1M if you're really desperate

Good luck

[deadastronaut]

i presume the 3.9M is for depth.  go high. i stuck a 4.7M in mine..

[Luke51411]

Ok thanks I'll try that and fire it up tonight!

[Luke51411]

Oops I meant to post a link to the build doc, just realized I didn't. I think my question was answered anyway. Thanks.

[Kipper4]

this one
http://www.madbeanpedals.com/projects/Smoothie/Smoothie.pdf

[Luke51411]

Yeah that's the one.

[Kipper4]

have you got and resistors you can put in series or parrallel to make the 3k9. as someone suggested earlier?

[Luke51411]

I have 2m2 and 4m7. I ordered some 3m9 resistors so I'll probably just wait since it is on a pcb and there isn't much real estate.

[Kipper4]

id just tack that 4m7 in and see as Dead Astro suggested

[Luke51411]

I got the p45 built and working with a couple hitches. The trimpot isn't smooth and wouldn't go past half until I forced it. I wonder if the cheap tayda 250k trim pots are actually 500k limited to half the travel.
My 2n5457s are matched within .002. I know this is a pretty subtle effect but would there be more phase if they were matched closer than that? I only get noticeable phase shift at 3/4 to the end of the pot travel though I think part of it is that I can't dial in the trimpot very good. I will switch out the trimpot tomorrow to see if I can get more range.

[jimilee]

My 2n5457s are matched within .002. I know this is a pretty subtle effect but would there be more phase if they were matched closer than that? I only get noticeable phase shift at 3/4 to the end of the pot travel though I think part of it is that I can't dial in the trimpot very good. I will switch out the trimpot tomorrow to see if I can get more range.

Mine sounds the way you've described also. May be normal.