Tone Pot Taper

[skelt101]

I'm hoping to get some help evening out the taper of the Tone pot on my Gretsch guitar. My issue is that almost all of the "action" occurs in the last quarter or so of the rotation, e.g. 0-3. The rest is very gradual. Any suggestions? Different taper and/or pot value? Different capacitor? For reference, the guitar is wired-up basically like this:
https://assets.ctfassets.net/3xaxfh...8aaf0bf2b01238e3e05210c3965eb1/TonePotRev.pdf
I'm pretty sure the Tone pot is a 500K Audio taper. Also, the Master Volume is now 1 Meg without Treble Bleed, and the Neck/Bridge Volumes are wired like the Master Volume, i.e. pickup to outer lug and wiper to switch. Thanks in advance for any help!​

 

[beaubrummels]

You could try moving the tone connection on the master volume over to the input lug first and see if that makes it better. Audio taper should work evenly for a tone control, but "50s wiring" messes with that. Do you keep the master on full or do you ride the master volume at all?

 

[ehdwuld]

do you have your tone wired to the jack as shown in the diagram?

if so I agree with the above

moving to the wiper of the master volume should be the same as the diagram

moving it to the outer leg of the MV or to the switch would be my suggestion

how do you have it

standard , 50s or 60s?

 

[skelt101]

You could try moving the tone connection on the master volume over to the input lug first and see if that makes it better. Audio taper should work evenly for a tone control, but "50s wiring" messes with that. Do you keep the master on full or do you ride the master volume at all?

I do use the Master Volume, especially in the "middle" pickup position. I like the way that '50s wiring cleans-up. In my (limited) experience, treble bleeds don't sound very natural. Perhaps I just haven't used the right one... You don't think a change in the Tone taper and/or pot value would help?

 

[skelt101]

do you have your tone wired to the jack as shown in the diagram?

if so I agree with the above

moving to the wiper of the master volume should be the same as the diagram

moving it to the outer leg of the MV or to the switch would be my suggestion

how do you have it

standard , 50s or 60s?

The Master Volume and Master Tone are wired-up just like in the Gretsch diagram. The only difference is the lack of a Treble Bleed on the Master Volume.

 

[freefrog]

What you've noticed is expected from a standard tone pot. From 10/10 to approximatively 3.5/10, such controls are mostly resistive and mainly flatten the resonant peak. It's only when the resistance becomes very low (approximatively under 7.5k between output and cap to ground) that the capacitor really enters in the game and shifts down the resonant peak toward a new frequency.

Different capacitors wouldn't change that.

A link about what I try to explain:

https://guitarnuts2.proboards.com/thread/7185/taper-pots-roll

The best way to deal with this, IMHO and IME, is to use a low resistance no-load pot (a 250k or even a 100k). Now, there's a downside: there will be a "pop" when the wiper of the pot will touch the resistive track.

Don't hesitate to Google "how to make a no-load pot", it could be useful.

 

[beaubrummels]

I do use the Master Volume, especially in the "middle" pickup position. I like the way that '50s wiring cleans-up. In my (limited) experience, treble bleeds don't sound very natural. Perhaps I just haven't used the right one... You don't think a change in the Tone taper and/or pot value would help?

Sure. I was trying to suggest the minimal option first.

 

[Hank-]

50s wiring causes this behaviour with the tone pot. The darkening effect you'd get with the tone pot if it was modern wiring is much different with 50s wiring.

At first it did throw me off a bit since I was used to working the tone pot to brighten up the sound from midway of its rotation when I had modern wiring and no treble bleed. With 50s I had to change my approach overall with working the controls, the tone control for instance behaves agressively below 3 on the dial as noticed by the OP, while the rest of the dial's rotation its behaviour varies depending on where the volume is set at. It starts functioning as a mild mid control sort of with the volume at 7 or so.

I don't see it as an issue per say but its how 50s wiring results are and not everyone likes it for that reason. I prefer the overall response of 50s wiring so I've switched to it lately on some specific guitars that see a specific use only.

 

[freefrog]

For the record, tone pots do the same thing with 50s wiring and modern wiring when volume pots are full up. It's only with lowered volume controls that it changes: tone pots with 50s wiring scoop the mids and shift up the resonant peak when volume controls are lowered while modern wiring make them behave consistently whatever is the volume setting.

So, what I've said in post 6 can be applied to 50s and modern wiring as long as the volume pots remain full up.

That being said and to come back on topic: cascaded volume pots and the low inductance typical of many Gretsch pickups are to take in account in this precise case, as factors diminishing the sensitivity of the signal to the master tone control.

It might be interesting to wire this master tone pot to the external lug of the master volume instead of letting it on the output jack. Not sure it will solve the issue but it should lead the tone control to behave differently (= with a more drastic effect) once the volumes lowered...

 

[skelt101]

Would the placement of the Tone in the signal flow affect anything? (I presume yes...) In the vintage '50s Gretsch guitars, the signal flow was a little convoluted:
Pickups->Selector Switch->Individual Volumes->Master Tone->Master Volume->Output Jack
In modern Gretsch guitars, the signal flow is:
Pickups->Individual Volumes->Selector Switch->Master Volume->Master Tone->Output Jack

 

[Teleplayer]

Are you sure the Tone pot isn’t 1Meg as well? Also check it is identified with code “A” for audio taper. “B” is for linear and I don’t recommend that.

I always use 500k Audio taper pots.

If you find the Tone pot isn’t effective you could try a lower value pot. However it will make the tone warmer even when set to 10.

 

[beaubrummels]

Would the placement of the Tone in the signal flow affect anything? (I presume yes...) In the vintage '50s Gretsch guitars, the signal flow was a little convoluted:
Pickups->Selector Switch->Individual Volumes->Master Tone->Master Volume->Output Jack
In modern Gretsch guitars, the signal flow is:
Pickups->Individual Volumes->Selector Switch->Master Volume->Master Tone->Output Jack

I'd like to see the 50's wiring. To my knowledge, it's almost impossible for individual pickup controls to come after any pickup selector switch; unless the selector switch worked by grounding out the pickup you don't want (but it might ground out the whole signal if done that way. I've never seen it. Would have to try it or draw it up to think it through).

 

[skelt101]

[No message]

 

[ehdwuld]

If you have two volume controls

They can be wired as independent controls by swapping the two ungrounded lugs on the pot

Switch the in form pickup and out to jack wires

In this way the volume of the second volume doesn't affect the first one

 

[freefrog]

If you find the Tone pot isn’t effective you could try a lower value pot. However it will make the tone warmer even when set to 10.

That's why I've suggested to change a low resistance pot in a no-load pot.

skelt101 : "Would the placement of the Tone in the signal flow affect anything?" Yes, as mentionned in my previous post, but I'm not sure it's an interesting solution.

Let's share below a 5spice sim botched in 5mn about that. It modelizes the "raw" resonant peak of a passive magnetic transducer. Vertical scale is in dB. Horizontal scale goes from 20 to 20 000hz, log scale.

The virtual pickup used in this sim has the DCR an inductance of a typical Filter'Tron. This sim wouldn't change that much if the virtual PU was a DynaSonic.

I've added a virtual cable of 370pF (= a typical 10' cable) and selected an input impedance of 1M, as in most amps.

Upper screenshots = log master tone from 10/10 to 0/10 with the stock 22nF cap then, on the right, with a 47nF cap. A 47nF cap gives a final resonance of 620hz approximatively VS 750hz with the original cap but as one can see, the other steps of the tone pot are not much different, to say the least.
pics under = PU volume and master volume set each @ 5/10. The master tone pot with its stock cap goes from 10/10 to 0/10 with the stock wiring (master tone @ the output jack, bottom left) then connected to the outer lug of the master volume... This last solution, bottom right, is closer to modern wiring and alters how the master tone behaves: it makes the sound darker in this case.

FWIW.

 

[freefrog]

... and below is what it would give with a 100k log master tone control changed in a no-load pot... Yes, the curve has 11 steps and no, the red line is not as pointy as in a no-load situation (I've forgotten to reset the simultation accordingly) but "you'll get the picture". ;-)

If the sound becomes too bright when a no-load tone pot is full up (IOW: out of the circuit), the solution is to connect the insulated (no-load) external lug to ground through a resistor. 500k would be a good starting point in this case, since it would emulate the missing pot load taming the brigthness even with all controls full up...

Again, FWIW.

 

[beaubrummels]

I don't believe that's an original 50's wiring diagram. AFAIK Gretsch wasn't using dual-ganged pots and treble bleeds in the 50's. Notice that one is using 1M pots to get around the cumulative affect of multiple resisters in the path. It's possible that diagram has the volumes after the switch because it appears that is a Gretsch tone switch being used as a selector, not a proper pickup selector switch. The tone switch works differently. The center is open and other positions around out the pickup not in use.

The TV Jones diagram I believe is closer to what it should be (note the pickup volumes are before the switch)

 

[skelt101]

I don't believe that's an original 50's wiring diagram. AFAIK Gretsch wasn't using dual-ganged pots and treble bleeds in the 50's. Notice that one is using 1M pots to get around the cumulative affect of multiple resisters in the path. It's possible that diagram has the volumes after the switch because it appears that is a Gretsch tone switch being used as a selector, not a proper pickup selector switch. The tone switch works differently. The center is open and other positions around out the pickup not in use.

The TV Jones diagram I believe is closer to what it should be (note the pickup volumes are before the switch)

The TV Jones diagram is the modern Gretsch wiring. The 1955 diagram is referenced from the Gretsch-Talk forum. It was the result of much research and verification against original examples. IIRC, DeArmond/Rowe supplied the wiring harnesses with the pickups. Not all guitars had the extra resistors on the individual volume pots. Here is a link to the discussion. You can read about it.
https://gretsch-talk.com/threads/diagrams-on-50s-wiring-for-gretsch.215069/

 

[skelt101]

Are you sure the Tone pot isn’t 1Meg as well? Also check it is identified with code “A” for audio taper. “B” is for linear and I don’t recommend that.

I always use 500k Audio taper pots.

If you find the Tone pot isn’t effective you could try a lower value pot. However it will make the tone warmer even when set to 10.

This is a really good question! The wiring diagram on the Gretsch website doesn't specify values for the pots, but (to my knowledge) Gretsch only offers a 500k audio taper for volume and tone as an aftermarket part. However, the 500k pot that I removed from the Master Volume position is definitely a linear taper! I bought this guitar used, so who knows if these are OEM spec. As for the existing tone, I won't know what it really is until it is removed. All of the markings are covered with solder. I have a 250k audio on deck for the tone position, and (if needed) 1 meg linear for the individual volume positions.

 

[Teleplayer]

Just to be clear. No issue using a linear taper volume control. However an audio taper tone pot is a better choice to avoid the issue mentioned on Post #1.