Voltage dividing pots with resistors between lugs 1 - 3

[Max9999]

Dear Stompboxers,

I have been simulating voltage dividing potentiometers with parallel resistors between the outer lugs in LtSpice. I have not been able to see a change in taper. I have been reading on the interwebs that it should, or is this only when they are used as variable resistances?

Yes I have been reading The secret life of pots. This situation is not mentioned.
I have attached a schem of something that gives me equal results.

Is it correct that the taper stays intact?

[idy]

I think the parallel R goes to wiper, not 1 to 3. By Interwebs you don't mean
http://www.geofex.com/article_folders/potsecrets/potscret.htm?

[idy]

Pretty sure yes, same taper the way you have it. 1M parallel should have no effect on the voltage read by the wiper. If you want to change the taper the parallel R needs to be in the circuit, not parallel to it. That is why your config is not in the geofex article.

[ElectricDruid]

I'd expect that the parallel resistor from one end of the pot to the other doesn't affect the taper.

Think about it - it's in parallel with the whole value of the pot, and moving the wiper doesn't alter the value of the pot, so nothing changes. All the parallel resistor does is reduce the overall value of the pot.

[FiveseveN]

I have been reading on the interwebs that it should

Lots of misinformation on these interwebs.

[bluebunny]

FYI, R.G.'s "Secret Life of Pots" article describes how to affect the taper by using a resistor connected to wiper and one end of a linear pot.

___
Edit: I see idy already posted this.   Not.  Enough.  Coffee.

[lomus]

I think the parallel R goes to wiper, not 1 to 3. By Interwebs you don't mean
http://www.geofex.com/article_folders/potsecrets/potscret.htm?

Some time ago I read this article on a spanish website (very interesting and recommended, btw):

http://www.pisotones.com/Potes/Potes.htm (Google translate has improved a lot in the last few years, in my opinion...  )

Anyway, it's very similar in content to the famous one by RG Keen @idy linked, but it also contains some data about simulations and interesting stuff about logs and tapers. Take into account it was posted a few years ago, probably when DIY pedal making was being born in Spain, so info related to prices and availabilty of materials won't be right nowadays - also be aware of the differences between countries markets and so on.

The whole site might be interesting for some of you too, from newbies to experts, since there is a lot of valuable info about components, tests, projects, procedures, PCB stuff and much more. If any admin wants to add the site to forum's resources, even though it's in spanish, I'm sure the authors would be so proud of their work and helpfulness - some of you might even know about it... Just my 2 cents I wanted to offer and put to your service.

"Calambres" is a well regarded, lovely human and pioneer in the music related DIY world (but sadly I have no connection with him at all...). You can also read about their history on the site. It was the first one about this passion in Spanish. Hope it's helpful for some of you. I recommend taking some time and wander around the pages to see if there's something of interest maybe. I should do it as well (sometimes I forget about the things I know haha)

[ElectricDruid]

Yeah, I know the Pisotones website, Iomus. It's great! I lived in Spain, years ago, and my Spanish still works if I knock some rust off!

[Matthew Sanford]

Just to piggyback, for changing log pot resistance it's approximately 80% of desired value between 1&2 and 20% between 2&3?

[Max999]

Thats perfect! So there is a way to lower a voltage dividing pots, if you want to preserve the taper, with the only penalty of an added resistor.

I got especially confused because of this thread https://www.ultimate-guitar.com/forum/showthread.php?t=1319500

Check post #10. What is this guy talking about?

[anotherjim]

^ He wrote a typo. As often happens in technical descriptions, the whole world reads some of it, nods sagely and fails to notice the errors.

[aikilo]

Thats perfect! So there is a way to lower a voltage dividing pots, if you want to preserve the taper, with the only penalty of an added resistor.

I got especially confused because of this thread https://www.ultimate-guitar.com/forum/showthread.php?t=1319500

Check post #10. What is this guy talking about?

Well, I can't access this link.

[ElectricDruid]

Really? Works ok for me.