# Questions about Frost drive AKA VFE Ice Scream



## ErickPulido (Oct 3, 2019)

Hi first time posting here, I was wondering about this PCB, but the dual C10k and W1M (edit it is D1M) potentiometers are not easy to get,
has anyone build one and sub the pots?

The description of this pedal makes me wonder how nice will make high gain amps into meltdown.


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## Nostradoomus (Oct 3, 2019)

You may try shooting a message to Peter at VFE to see if he has any stock left, he’s really nice about this kinda stuff.


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## Nostradoomus (Oct 3, 2019)

Also the folks on madbean recommend using a B1M instead of W taper as it seems they aren’t in production anywhere.


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## ErickPulido (Oct 3, 2019)

Nostradoomus said:


> You may try shooting a message to Peter at VFE to see if he has any stock left, he’s really nice about this kinda stuff.


I'll ask him about it, thanks


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## ErickPulido (Oct 3, 2019)

My bad, W1M is D1M I guess B1M  will work well still


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## Nostradoomus (Oct 3, 2019)

Oh if it’s a D taper use A as a replacement


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## ErickPulido (Oct 3, 2019)

Nostradoomus said:


> Oh if it’s a D taper use A as a replacementView attachment 1652


Awesome info, thank you so much


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## Devoureddeth (Oct 3, 2019)

I would make the Dual C10k if Peter doesn't have any. I bought the cheap Tayda pots and picked the wafers I wanted. It is pretty easy requires some pliers and a steady hand.


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## ErickPulido (Oct 3, 2019)

Devoureddeth said:


> I would make the Dual C10k if Peter doesn't have any. I bought the cheap Tayda pots and picked the wafers I wanted. It is pretty easy requires some pliers and a steady hand.


I am not that good with my hands that would be my last option, already saw how to do it, thanks


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## Chuck D. Bones (Oct 5, 2019)

I just finished a Frost Drive build.  I'll post some pix in the Build Reports forum over the weekend.
I corresponded with Peter Rutter.  He has some residual stock, but the C10K duals he has are 9mm and won't fit the pad pattern on the Frost PCB. 

Here's the thing about the MID pot... rev audio (C taper) is the wrong taper for this circuit because the MID pot is wired backwards.  CCW rotation makes the frequency of the mid hump go up; CW rotation makes it go down.  As designed, the MID pot does not space the tuning out evenly, the top half of the rotation makes essentially no change in the tuning and the bottom half is too sensitive, especially near zero.  See the simulation results below.  Actual operation agrees.  Two options:
1) Use an A10K dual, they're much easier to find.  The rotation will still be backwards, but the tuning will be spread evenly. 
2) This is the one I chose.  Use a C taper pot and wire it backwards.  If you want smooth tuning and normal rotation (CW makes the frequencies go up), that's what you have to do.  It's actually pretty easy.  Tie pin 1 on each gang of the pot together.  No need to connect pin 1 to the board.  Tie both pins 2 together and connect them to one of the pin 2 pads on the board, doesn't matter which.  Connect each of the pin 3 terminals on the pot to the pin 1 terminals on the board, separately.  If you think this sounds crazy, take a look at the schematic and you'll see why it works.  We still have the problem of obtaining a C10K dual.  I solved it this way: C100K duals with solder lugs are available from Pedal Parts Plus.  There is nothing magic about 10K pots.  Any reasonable value could be used as long as C3, C4, R4 & R5 are scaled accordingly.  I made the pot resistance 10x bigger, so the impedances of the other 4 parts had to scale up by 10x as well.  That means R4 & R5 are now 10K, C3 is 4.7nF and C4 is 12nF.  Note that the PCB silkscreen and the schematic both have typos for C3.  The BOM is correct (47nF).  You can find the VFE Ice Scream schematic on MadBean's website.  It has the same reverse rotation / wrong taper issue, but it does have the correct value for C3.   

I used A1M for the DRIVE pot, it works fine.  B1M will make the bottom end of the range too sensitive. 

Mid Boost tuning (as designed).  Each curve represents setting the MID pot to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.




Mid Boost tuning, corrected.




Here's a pic of how I wired the MID pot.


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## ErickPulido (Nov 15, 2019)

Chuck D. Bones said:


> I just finished a Frost Drive build.  I'll post some pix in the Build Reports forum over the weekend.
> I corresponded with Peter Rutter.  He has some residual stock, but the C10K duals he has are 9mm and won't fit the pad pattern on the Frost PCB.
> 
> Here's the thing about the MID pot... rev audio (C taper) is the wrong taper for this circuit because the MID pot is wired backwards.  CCW rotation makes the frequency of the mid hump go up; CW rotation makes it go down.  As designed, the MID pot does not space the tuning out evenly, the top half of the rotation makes essentially no change in the tuning and the bottom half is too sensitive, especially near zero.  See the simulation results below.  Actual operation agrees.  Two options:
> ...


Don't know how I missed this, Thank you so much Chuck, I'll build one soon with this mod


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## Chuck D. Bones (Nov 15, 2019)

Take a look at my post in the *Modifications *forum.
Wiring the diode mod is a little tricky.  I screwed it up on the first try.  If you follow my instructions, it will work.  If you have questions, feel free to ask.


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## ErickPulido (Nov 15, 2019)

Chuck D. Bones said:


> Take a look at my post in the *Modifications *forum.
> Wiring the diode mod is a little tricky.  I screwed it up on the first try.  If you follow my instructions, it will work.  If you have questions, feel free to ask.


Thanks I am still waiting for the PCB it takes forever to get to Mexico


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## Mike McLane (Mar 22, 2020)

OK boys and girls, let's get this straight for the "paint by numbers" crowd .  .  . a simple recipe for getting the thing to work as basically intended 1) sub a dual A10K for the MID control pot, 2) sub an A1M for the DRIVE pot, 3) leave C3, C5, R4, R5 as spec'd in the BOM??  MID control will work "backwards".  That do it???

Chuck B, does this also address your comments re: the "corruption" of the MID control as referenced another post or is that yet another matter for consideration?


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## Chuck D. Bones (Mar 22, 2020)

First of all, you should be using the 9-1-19 rev Build Docs.  The earlier rev had a typo in the parts list & schematic.

Everything you says is correct, that is the simplest solution and the only downside is the MID pot rotation is backwards.  The backwards rotation in combination with the wrong taper is the corruption to which I was referring.

It is critical for the MID pot to have a good ground to the case.  My enclosure was thoroughly powder coated inside and that prevented the MID pot from grounding properly.  I had all sorts of intermittent problems until I scraped the paint off of the inside of the enclosure around all of the pot and 1/4" jack holes.


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## Robert (Mar 23, 2020)

Chuck D. Bones said:


> Everything you says is correct, that is the simplest solution and the only downside is the MID pot rotation is backwards.



There's no need to sub the MID pot anymore, the PCB has been updated so the C10K behaves as it should.

You can tell if your PCB is the new revision by looking on the back just below the "PCB175" text.  If it says "Rev2" or newer you have the updated version.   Since you just ordered yours (Mike) it will definitely be the updated version.


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## Chuck D. Bones (Mar 23, 2020)

So now it's just down to finding a 16mm C10K dual.


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## Robert (Mar 23, 2020)

Smallbear has C100K duals now, so all that would be required is to scale the previously mentioned values.









						Alpha Dual-Gang 16mm PC Mount
					

Small Bear Electronics DIY Parts




					smallbear-electronics.mybigcommerce.com


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## Chuck D. Bones (Mar 23, 2020)

Yup saw those.  SB has C100K dual with solder lugs.


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## Robert (Mar 23, 2020)

They have the proper right angle PCB mount now.     

This is good news for the Photon Vibe and another upcoming project as well.


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## Chuck D. Bones (Mar 23, 2020)

Well Friggy-Diggy!  Almost makes me want to build another one.  After I get done with the 7 or 8 in the queue.


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## Robert (Mar 23, 2020)

Build docs updated with link to C100K and info about component value substitutions.


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## Mike McLane (Mar 23, 2020)

So if going with C100K. . . C3 = 4.7nF, C4 = 12nF, R4 & R5 = 10K. . . for Chucky's wider tuning 6.8, 18, 6.8K respectively.


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## Mike McLane (Mar 23, 2020)

BTW FYI, just DL'd the updated Build Docs and didn't notice the revisions "PedalPCB" noted in the comment immediately above.


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## Robert (Mar 23, 2020)

It's there, Page 2.



			http://pedalpcb.com/docs/FrostDrive.pdf


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## Barry (Apr 19, 2020)

Looks like I have the old boards, so looks like I need C100K dual with solder lugs, would A or B taper if I can find them work as well?

Edit: I have A10k and A100K dual gang on the way (went ahead and got some in B taper as well)


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## Chuck D. Bones (Apr 19, 2020)

If you use B taper, the top end of the freq range will be crowded at one end of the rotation.  If you use A taper, then don't reverse the pot wiring, wire it straight to the board.  The high frequencies will be at the CCW end of rotation, but it will all be evenly spread.  If you use the A10K, then you don't need to change any component values.  HOWEVER, C3 should be 47nF.  In the build docs dated 09.01.19, it is wrong in the BOM & schematic.  It is also wrong on the silkscreen.


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## MightySmallElectrons (Apr 19, 2020)

Am I understanding correctly that the Dual A10k option will just make the knob function backwards to the original? My understanding is that the taper is the same just reversed?


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## Chuck D. Bones (Apr 19, 2020)

Yes and yes.  
A taper spreads out the CCW end of rotation.  Noon is 15% of the resistance (measured from pin 1 to pin 2).  C taper spreads out the CW end of rotation.  Noon is 85% resistance.


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