How is a Resistor going to change the thickness of the carbon trail along the path of the W wiper?
You can get close with Potentiometers that start out with the Same taper!
It wouldn't, which is the point. The only thing that would change would be the total resistance of the pot. The carbon trail would still "taper" in the same manner...distributing the total resistance as dictated by the thickness..at 9:00 the % would be the same with or without the resistor, right?
After reading back though this, I think I see the issue. I was not suggesting you can transform the taper of a pot (my apologies for any lack of clarity). I am stating that you can change a pot of the same taper to a different value.
A 1MΩ linear (or "A") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ linear taper pot.
A 1MΩ tapered (or "B") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ tapered taper pot.
A 1MΩ reverse-tapered (or "C") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ reverse-tapered taper pot.
A 1MΩ wide-tapered (or "W") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ wide-tapered taper pot.
I'm not sure these replicate some of the standard tapers, but so what. Seems like there are some options to make some new tapers along the way, especially if you want to use different value resistors between terminals 1-2 and 2-3.
I just re-read that, thanks. Actually, he was discussing modifying the taper between wiper and lug. Apples to Oranges as they say. In the extremely limited bonehead caveman tests I did, the tapers remained pretty darned constant when using a resistor from lug 1 to 3 (NOT a taper resistor between wiper and lug). Again, I am an uneducated hack so I'll just retract my statement. I certainly don't want to mislead anyone.
BAH, wrote the following yesterday or whenever... but didn't hit "Post reply"
"Well it seems I'm due for a re-reading of Mr Keen's horticulture tome for DIYers, I'll pay more attention this time to the taper-resistors and the non-taper 1—3 combo."
Right you are Fig, it was the Taper-resistors between outer lug and wiper I was recalling through my foggy memory.
@finebyfine ‚ thanks for the link. I usually will link stuff like that, but I'm getting lazier the older I get, I guess. Also, it is tough to find, that particular link/page. Sometimes I find it easily, but mostly I have to hunt for it.
BAH, wrote the following yesterday or whenever... but didn't hit "Post reply"
"Well it seems I'm due for a re-reading of Mr Keen's horticulture tome for DIYers, I'll pay more attention this time to the taper-resistors and the non-taper 1—3 combo."
Right you are Fig, it was the Taper-resistors between outer lug and wiper I was recalling through my foggy memory.
@finebyfine ‚ thanks for the link. I usually will link stuff like that, but I'm getting lazier the older I get, I guess. Also, it is tough to find, that particular link/page. Sometimes I find it easily, but mostly I have to hunt for it.
After reading back though this, I think I see the issue. I was not suggesting you can transform the taper of a pot (my apologies for any lack of clarity). I am stating that you can change a pot of the same taper to a different value.
A 1MΩ linear (or "A") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ linear taper pot.
A 1MΩ tapered (or "B") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ tapered taper pot.
A 1MΩ reverse-tapered (or "C") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ reverse-tapered taper pot.
A 1MΩ wide-tapered (or "W") - solder 1MΩ resistor from lug 1 to 3. It will now be a 500KΩ wide-tapered taper pot.
Plenty has been written by others on this topic, so I won't repeat any of that stuff about pot construction or paralleling resistors. It is clear from the literature that when you put a 1MΩ resistor in parallel with a 1MΩ pot, whatever the taper, you will end up with a different taper. Whether that matters to the circuit depends entirely on the circuit, what the designer intends to achieve and whether the designer knows that they are doing. Paralleling a W-taper pot is particularly problematic, so I will discuss that one.
W-taper pots are common in TS pedals. First, let's examine why the designers at Ibanez selected a W-taper pot in the first place. Consider the LGSM below. Rather than bore you with the math, I'll demonstrate the effect of taper and paralleling a pot by running some simulations in LTSpice.
I'm simulating just the stuff between IC1 pin 1 and C7.
Here is the family of curves for the circuit as-designed. Each curve represents the frequency response at the dial settings 0, 1, 2, 3... on up to 10. The green curve on the bottom is with the TONE pot at 0. Look at what's going on at 2KHz. From 0 to 3, the curves are pretty evenly spaced. Curves 3, 4 , 5 & 6 are bunched up together. From 7 on up to 10 the curves are spaced fairly far apart. You will notice when turning the TONE knob on a TS that it's pretty sensitive to rotation near 0 and 10, particularly near 10, and there's not much change near the center of rotation.
Here's the same set of curves with a B20K pot. Notice how all of the curves except the top and bottom curve are bunched up in the middle. This is why no one (well almost no one) uses a B-taper TONE pot in a TS.
OK, now let's look at what happens if we don't have a W20K pot and we try to make one by paralleling a resistor.
This is the curve for a W50K pot with a 33K resistor from pin 1 to pin 3. It now measures 20K from pin 1 to 3, but look at the curve spacings. The top and bottom curves are more separated from rest and the middle curves are more bunched up.
This is the curve for a W100K pot with a 25K resistor from pin 1 to pin 3. It measures 20K from pin 1 to 3, but look at the curve spacings. The top and bottom curves are even more separated from rest and the middle curves are more bunched up. Looks a lot like the B20K curves, doesn't it?
We get a similar effect if we use two parallel resistors, one from pin 1 to pin 2 and one from pin 2 to pin 3.
Talking up electronics with Chuck is like taking that lick you think you've owned to a jam, only to have the other guitarist play it who really owns it
Talking up electronics with Chuck is like taking that lick you think you've owned to a jam, only to have the other guitarist play it who really owns it
Yes, that seems likely at least in my case given what I've read. You are extremely knowledgeable as well and I applaud you both (and others sharing their wisdom).
Pretty simple rule. According to Kirk, however many Klingons into the transporter, the same number must re-materialize on the other side. The fun part is applying that principle to the circuit as a whole (or black hole in this case).
