Smoothie mix pot

[midwayfair]

I'm thinking of doing this mod since I am more likely to use the phaser more if I can make it even subtler. Smallbear has the reverse audio 500k 9mm pots, so the required parts are obtainable for any of us already building mini pedals to fit both controls.

I'm going off Justin Philpott's mod: http://www.lynx.bc.ca/~jc/phase45modded.gif

Just want to make sure I've got it right on the board itself, since it's easy enough to see what's replaced in the schematic. R15 and R16 are the 10K resistors to replace with a 25K pot.* Lug 2 goes to the terminus to the right side of the chip in the R15 slot; Lug 1 goes to the other terminus in the R15 slot, and lug 3 goes to the right-hand terminus in the R16 slot.

*Justin lists 22K, which is ideal, but that's not a value available to us in mini pots - so we might have to be content with just measuring a 25K for as low a value as we have on hand. Is there another way to handle it? Changing the pot value will also change the law of the pot. Maybe instead of replacing the two resistors, putting a pot across either R15 or R16 to change the value of that resistors by itself?

[calciferspit]

I've seen the 20k "w" TS tone pot in 9mm. I'd think that might be worth a shot.

[oldhousescott]

Yep, I believe you've got it. A 25k linear pot should work fine replacing R15 and R16 as you've described. I might be tempted to put a 1k resistor between the OUT terminal and the 3PDT just to protect the output of the opamps against a short, but it's not technically necessary and unlikely to be needed.

[guycapuano]

Did you ever get this mod done? 

[midwayfair]

Here's the build report with a gut shot: http://www.madbeanpedals.com/forum/index.php?topic=5484.0

Edit: Sorry, just reread my post. Lug 2 goes to the connection to C6. The other two lugs go to the terminals at pin 1 of each IC.

[guycapuano]

Just put a mix pot on mine, WOW so useful. i also did a rate LED mod!

[midwayfair]

Just put a mix pot on mine, WOW so useful. i also did a rate LED mod!

Yay! Glad it worked out well for you. I kind of wish I'd done the rate LED, too, at times.

[kinski]

I JUST built the Smoothie with the Uni-vibe mod. Fantastic! I never really like phasers, but this sounds beautiful!

Now, I'd like to add the MIX pot. I already removed R15 and R16.

So, I just want to double check to make sure I have this right:

LUG 2 --> Right side of chip at R15
LUG 1 --> Other hole of R15
LUG 3 --> Right hand of R16

Is this correct?

[midwayfair]

Is this correct?

Yup.

[kinski]

Thanks! Just made it happen. Really great. You can get more subtle phasing or some nice vibrato. What a great circuit this is. Time to start painting and drilling!

Thanks to Madbean for a great board and everyone who contributes to the mods!

Happy New Year!

[HailToTheBlues]

Hi,
i intend to do the mix pot mod to my smoothie, so i just wanted to ask one thing: i need to remove the r15 and solder the lug 2 to the right side and the lug 1 to the left side of the r15. Then i need to solder the lug 3 to the right side of the r16, and what about the left side of the r16? do i leave it empty?

Best regards