Taper of pots not good

[mrut]

I replaced the pots in my SE DGT with cts pots of the same value. I don't care for the taper. The largest change happens between 8-10. 9-10 is really noticeable. I'm not sure if it is the treble bleed network causing this or the taper of the cts pots. Any suggestions? I didn't notice this with the original Alpha pots.

The cts pots are the normal pro guitar pots with brass shaft.

 

[mrut]

I also noticed that my treble bleed has both a cap and resisitor where the PRS USA pots just come with a cap.

 

[shimmilou]

Pots come in various tapers, audio "A", linear "B", etc. CTS is just the brand, you have to specify the taper too.

 

[mrut]

They are both 500k audio pots.

 

[shimmilou]

PRS uses a "custom taper". Sounds like you might like a linear taper better.

 

[mrut]

It appears for the DGT model that it uses a 475k pot. I just ordered them from the PRS store to see if they make a difference.

 

[Dirty_Boogie]

You'd be amazed at the variance in pot values. It's not unusual to measure 20% variance, even on higher end pots from CTS and Bourns. 475K is considered "acceptable" for a 500K pot. It's strange they'd spec 475K pots on the DGT, unless they were specifically measuring every one before installing.

Also, if you're seeing such a rapid change in the last 10% of turn, I'd switch to Linear (B) taper for the volume pot. While Audio (A) taper is more common for volume controls, I've had a few guitars over the years that just seem to behave better with linear volume pots. It might be something to do with the treble bleed.

 

[mrut]

It seems really weird to me that they would use 475k pots but I saw this on the description:

Designed for surface-mounting, this potentiometer offers 475k ohm resistance and features
a 180pF capacitor type for better frequency handling. The 180pF capacitor acts as a high
pass filter removing shelved low-end, allowing high frequencies through for more clarity and musical highs as you roll the volume off. *Values specified for model specifically (applies to resistance values)
Compatible with PRS DGT

I wonder if the SEs use a different value. The ones I took out were stamped 500k but actually measured closer to 550k with a meter. Wonder if the imported pickups require a different value.

 

[SinSir]

Core or RS guitarworks are the taper I like. I used to use RS, but have since moved to PRS core. I've used them in se, s2, core, and even a couple other makers.

 

[Tone-y]

The core prs 500k pots have a taper I like too. Even got one in my Strat.

I find the treble bleed affects the taper at the other end of the scale - where the volume comes on very quickly to start. Haven't noticed anything around the full up

 

[mrut]

I put in the 475k PRS pots. They sound good and have good taper. I tried disconnecting the 1meg resistor that came tied across the outside lugs and really couldn't hear any difference, so not sue I understand why they are on there.

 

[Bluescb]

I took my alpha 500K out of my DGT SE and it measured 568K. I did that cause when I roll volume back from 10.. its almost like a Notch between 8 and 9. Drops off way too fast. When I have both pups on and roll back... say the neck pup, when it hits 8.5 instead of a smooth blend.. it snaps into the bridge pup. Drives me to where I can't use it live.
Ordered a CTS 500K but it's too big for the drill hole in the dgt. You think getting a PRS pot instead of the Alpha will fix this?

 

[JasonE]

I put in the 475k PRS pots. They sound good and have good taper. I tried disconnecting the 1meg resistor that came tied across the outside lugs and really couldn't hear any difference, so not sue I understand why they are on there.

The resistor is there to fix any issues caused by the treble bleed. It isn't always needed. The capacitor is what is letting the high frequencies bleed through. Adding a capacitor for this purpose can mess up the taper of the pot with some guitars. The way you fix that is to put a resistor in parallel with the capacitor. You wouldn't hear any difference between having the resistor there or not there. You could definitely have a difference in how the volume turns up and down with and without it.

 

[DreamTheaterRules]

Sadly, even in this day of very precise cap and resistor values, pots are still the wild card, and "standard" variance range is 20% from spec'd value. If you think about that, a 500K pot could be from 400-600 and still be in the tolerance range the manufacturer quoted. And if you think about that. the variance from 400 to 600 is literally 50%! (Side note: David Barber once said that he tested every pot he bought, and used only around 15-20% of them that were very close to quoted value, then bulk sold off the others on ebay. He said he typically bought 100 pots to find 15 or so usable ones in his pedals!)

If you want to do your own amateur version of TCI'ing your pickups, you can tune the pots yourself with added resistors. In the case of guitars that add both a cap and resistor, it can still be done but you need a little more knowledge or R/C networks, a range of caps and resistors to try and exact value of your pot. It's also a good idea on even new pots to get them a thorough cleaning with Caig De-Oxit before installing them.

 

[DreamTheaterRules]

The resistor is there to fix any issues caused by the treble bleed. It isn't always needed. The capacitor is what is letting the high frequencies bleed through. Adding a capacitor for this purpose can mess up the taper of the pot with some guitars. The way you fix that is to put a resistor in parallel with the capacitor. You wouldn't hear any difference between having the resistor there or not there. You could definitely have a difference in how the volume turns up and down with and without it.

Actually, your post makes me curious as to exactly how they are using the R and C in the DGT, since there is obviously more than one way to do it. Anyone have a schematic for this?

 

[theDeepender]

The resistor is there to fix any issues caused by the treble bleed. It isn't always needed. The capacitor is what is letting the high frequencies bleed through. Adding a capacitor for this purpose can mess up the taper of the pot with some guitars. The way you fix that is to put a resistor in parallel with the capacitor. You wouldn't hear any difference between having the resistor there or not there. You could definitely have a difference in how the volume turns up and down with and without it.

Yup.
That’s what I had to do to fix the taper on mine.

 

[JasonE]

Actually, your post makes me curious as to exactly how they are using the R and C in the DGT, since there is obviously more than one way to do it. Anyone have a schematic for this?

HERE

 

[DreamTheaterRules]

HERE

Wow! This is one of the more complex ones I've seen. No surprise there, given how tone driven DG is. It's interesting that someone would complain about the range of the knobs and so forth here... they've clearly gone WAY farther than usual, to get things the way DG wants them. Multiple caps and resistors added to balance the pickups tone and volume when switching them. Very interesting setup.

 

[JasonE]

Wow! This is one of the more complex ones I've seen. No surprise there, given how tone driven DG is. It's interesting that someone would complain about the range of the knobs and so forth here... they've clearly gone WAY farther than usual, to get things the way DG wants them. Multiple caps and resistors added to balance the pickups tone and volume when switching them. Very interesting setup.

My DGT is a 2011. It has different values for the resistors on the taps than the current model. Mine uses 2.2k and 8.8k. I would have to pull the backplate but I don't remember seeing the 10M resistors in it when I looked at it. I am not sure when they introduced those.

 

[DreamTheaterRules]

My DGT is a 2011. It has different values for the resistors on the taps than the current model. Mine uses 2.2k and 8.8k. I would have to pull the backplate but I don't remember seeing the 10M resistors in it when I looked at it. I am not sure when they introduced those.

How does it do for volume rolloff cleanup, and general pot sweep? Seems they went a long way to make these things work well. On the import line, I just have to assume that pot variances may be at fault for the complaints.