General tech questions

volume pot question

1

I use the volume pots on both of my Gretsches to roll off the volume of the guitar for vocals and max the guitar volume for a slight overdriven sound with soloing. The problem with these guitars, 6120 and 6128t, both fender era, is that the volume pots are so sensitive that rolling back will cut the volume too much, too quickly. I've read about the audio taper vs. linear taper pots, but need the help of the experts here to correct the problem. Can someone help me resolve this issue?

thanks

2

Treble bleed is your answer.

I installed it before in my SSLVO, but never liked it. I miss the "blanket" tone for rhythm. So I removed the mod. Plus it's hard to do volume swells if your the knob is "usable" from 1 to 10.

My solution: Move back the master volume to around 7-8, swith both pickups, full volume on invidual pickups, full tone.

Then work around the amp, adjust treble, volume, grit to taste. This will be your rhythm tone.

Then when the solo hits, move the master volume to 10, switch to bridge if needed, you'll be suprised how much gain is added, the filtertrons excel on this.

It gets time to get used to switching using your hands, but hey, nobody wants to see a guitarist tap dancing on stage.

3

I use pretty much the same approach as JetBunny. I like to set my guitar volume between 7 and 8 and have something in reserve for solos. There is one other wrinkle that I'd like to add however.

A little trick that I've learned to employ is to control volume by the absence or presence of the pick. If I play rhythm using my thumb with the pick "palmed" and then switch to the pick when it's time to solo I can accomplish a change in volume, tone and attack all in one fell swoop. Just an idea . . .

4

That's I'm doing, now, but the volume gain is so sensitive that when I roll up or back there is too much change in the volume. I'll give it another shot at band practice this afternoon.

thanks for the reply.

5

Do the linear taper pots require more twisting of the control to affect the volume? If so, then that sounds like the solution I'm looking for...I want to control the volume/drive but have it occur gradually from 3 or 4 or even 5-10.

thanks

7
ChrisP said: Now time to hit "add post" and roll the proxy error dice

and we have a winner!

Chris, this is your day!

8

Well I tried rolling off the volume tonight and man what a loss of treble. I like to use many pedals and wish to keep it simple. Sounds like the linear taper might work for me. Is there a thread with details on replacing pots in the forum? and which linear pot and where should I shop to buy said volume pot?

Thanks chrisp, I'll read up some more and gain a better understanding.

tggs

9

Chrisp, thanks for remembering the link! I'm not mighty though, just a humble dude! lol :grin: Thanks though!

10

I second Wenzel's solution.

Keep us posted.

11

I read Wenzel's post on the treble bleed mod and I don't think I need or want a linear pot. How do I determine which pot my axe has?

12

tggs, I want to say that all Gretsch guitars that are new come with a linear taper pot. Not sure about the Setzer models or the vintage ones, but the new ones all behave in the same way. When you roll off the volume they become dull, dark and to my ears, more lifeless. That's why I went with the treble bleed and audio taper pot. I'd call TV Jones and ask them for a CTS audio taper pot with treble bleed caps installed. They tack solder them on, so installation is that much easier. You still have to solder the wires from your guitar, but it takes a lot less time to do this.

Good luck!

13

I think mine are linear, both my 6128 and the 6120 become "dull, dark... more lifeless," The TV Jones route sounds like the answer.

One other thing. The switches for pick-ups and 'mud" are shorter on my Nashville than on my duo jet. The longer ones are easier to grab. Does TV have those as well? If not where do I get the longer (taller)ones for my Nashville?

this forum is great- I really appreciate you guys' input- thanks

14

Guys, I'm very confused.

I have no reliable independent expertise in this: until our last discussion, while I remembered the names of the two sorts of pots, I couldn't consistently remember which one produces the effect I want. So, the last time we had this discussion, I asked.

I thought the eventual consensus then – with input from apparently technically knowledgeable people – was that linear taper does NOT produce a steady, gradual change in perceived output throughout the entire travel of the pot, because of the unique psycho-acoustic mechanics of human hearing. (That is, that it takes 10 times the power to produce twice the change in apparent volume.)

So a pot which produced a steady electrical increase – one unit of power for one unit of travel across its range – might give smoothly gradual results for running a motor, but not for consistent increment or decrement of volume or tone in an audio circuit.

I thought it was log-taper, or audio taper, pots which produced the steady increase in effect most of us want under guitar knobs – by increasing current logarithmically per unit of travel along the wiper.

This seems the opposite of what is now being proposed.

Since the theoretical bases of guitar wiring persistently elude me, I have always to refer to practical experience. To wit: most Gibson and other guitars I own have controls with pretty smooth response. Starting from knob-off zero, a pickup starts to become audible by 2 or 3 on a speed knob, and increases fairly consistently and predictably from there on up to 10, where it's full wide open. Same with many (not all) tone controls.

It has at various times been my understanding (like when I've just studied up on it again, between forgettings) that audio-taper pots produce that smooth result. StewMac, for instance, seems to sell nothing but audio taper pots.

I won't say that Gretschs are the ONly guitars that behave differently – there may be others – but they DO behave differently. From off up to 6 or 7, there's very little increase in apparent volume (or brightness, if we're talking tone pots). Then it comes on fairly suddenly between 7 and 10.

That's where all the adjustability seems to be, and that's what lots of us don't like. (I've gotten used to it, and just make micro adjustments, considering it one of the little things I deal with for the sake of getting Gretsch tone.) But every time I play a Gibsonesque guitar, I'm pleased and delighted with the ability to use nearly the entire travel of the pot to make adjustments.

I had THOUGHT we'd determined that last time out that Gretsch was using LINEAR taper pots, which were responsible for the paradoxically non-linear effect we're so familiar with, and that switching to AUDIO taper would give us back 2 - 7 on our knobs.

Did I get it dead backwards somehow?


I am not questioning the whole treble bleed discussion, as I personally don't mind the darkening effect of turning volume down a bit. (In fact, on tone-switch equipped guitars, it's a very handy way of just taking the edge off without going all the way to a tone-switch setting.)

15

You want AUDIO taper for AUDIO purposes... like volume pots. TV Jones recommends these. I recommend these. And Proteus, you are correct in your deduction as to why audio taper reacts better for our purposes, and is corroborated by your observations.

So, tggs, you want a pot with the markings: A500k

= logarithmic (aka audio) 500kiloOhms potentiometer.

If you want an on/off switch for your volume control, stick with the stock linear pots Gretsch uses (i.e. B500k).

P.S. In addition to being linear taper pots, the stock CTS pots Gretsch uses are also extremely raspy feeling imo. I swapped out the pots on my anni for Alpha brand audio tapers. Much better twisting feel, and are usable as volume controls now. And the TVJ treble bleed is just mint on this anni.

16

I've swapped three volume pots from three different gretsch guitars.

Replaced them with clearly marked and measured audio taper pots and no more on/off dial.

IMO, the CTS pots are not all that.

R.G Keen in "Secret Life of Pots" said:

Volume controls are different. The human ear does not respond linearly to loudness. It responds to the logarithm of loudness. That means that for a sound to seem twice as loud, it has to be almost ten times the actual change in air pressure. For us to have a control pot that seems to make a linear change in loudness per unit of rotation, the control must compensate for the human ear's oddity and supply ever-increasing amounts of signal per unit rotation. This compensating resistance taper is accurately called a "left hand logarithmic taper" but for historical reasons has been called an audio or log pot. In these pots, the wiper traverses resistance very slowly at first, then faster as the rotation increases. The actual curve looks exponential if you plot resistance or voltage division ratios per unit of rotation.

If you used an audio/log taper pot for the control of the power supply we mentioned, the output voltage would increase very slowly at first, creeping up to maybe 10% of the final output at 50% of the pot rotation. It would then blast the other 90% in the last half of the rotation - very hard to control. Likewise, if we used a linear pot for volume control, the volume would come up dramatically in the first half of pot rotation, and then do very little change in the last half.

17

Ok, now let's see if we can get the lid back on this can of worms.

It sounds like I need to order an audio pot with the treble bleed. 50K per Wenzel or 500K per ADR? I just want to make sure that I order the correct one. :?:

18

500K.

the 50K is probably a typo, as all the high end of your signal will be shed to ground. i.e. MAJOR tone sucking.

19

I ordered the 500K audio taper with the treble bleed for both of my gitters, today. I sure hope I can manage to install them properly. I'll keep you posted.

TV Jones sales people were pleasant and helpful on the phone-nice folks!

20
tggs said: I sure hope I can manage to install them properly.

If you can solder with any degree of proficiency it'll be a breeze.

21

Vintage Gretsches had 1 meg pots. New ones have 500K. Linear vs. audio isn't a big deal. They all go from all the way up to all the way down. Don't overthink these thngs. BZ

22

I think linear pots tend to give a smoother response in a guitar. An audio pot has the most change between 6 and 10. Guitars are usually played with the volume wide open, and turned down occasionally to clean up the tone. Having all the change at the top makes them touchier when you're trying to just it off a little. It's the opposite with amps, where you rarely play on 10, unless you're in X. Audio has most of the change at the top Reverse audio has most of the change at the bottom Linear , 5 is halfway, both electrically and physically log taper is pretty close to audio, I don't think you'll hear any difference.

Loss of treble when you turn down is due to the stray capacitance as you increase the resistance in the circuit. You can add a small cap from the top of the pot to the wiper to eliminate loss of highs. You'll have to experiment for the right value.

23
BillZoom said: Loss of treble when you turn down is due to the stray capacitance as you increase the resistance in the circuit.

Not really. It is more a matter of impedance matching and the lack-of-robustness of higher frequencies due to variety of reasons, including inductance properties of pickups. As a pot is turned down, the impedance (resistance to sine wave signal) is less, and the high frequencies are more likely to be shed to ground, with the bass frequencies still staying in the signal path.

(I'm gonna rehash a previous post of mine).

=============== Treble bleed and pots with high end roll off:

It prevents highs from being shunted to ground. Once a portion of signal has passed to ground, it's gone to the great voltage bucket in the sky.

RC circuits are the most primitive tone filters. Where R = resistor C = capacitor. If you put a resistor in series (tone control pot) with a cap to ground, then you get a low pass filter. Low frequencies pass thru while shunting the highs as resistance is lowered.

(e.g. Tone control)

If you have a cap in series (the treble bleed cap), with a resistor to ground (volume pot), then you have a high pass filter. As resistance is lowered, then only the low frequencies are shunted to ground, allowing highs to pass.

(e.g. treble bleed volume pot)

A potentiometer is more than just a resistor. A pot allows you to choose a path by how much resistance is applied... kinda like a fork in the road, but one is jammed up with cars, so you decide to take the road with less jamming up. One path goes over a cliff, and the other goes to the city. The jamming up changes frequently. You really don't care which one you take as long as you get to keep moving. That's what's known as taking the path of least resistance. Electrons are dumb, obviously.

Now a high pass circuit is kinda like a narrow bypass lane that only the smaller cars can fit thru. Because not all cars are small, there is almost always less traffic and the path moves brisky, circumventing the heavy jammup on the main road. In this case the bigger trucks (low frequencies) can't move or are diverted off the cliff, but the smaller (higher freqencies) can breeze thru quickly to the city (amp).

=============

24

Was this city built on rock & roll?

25
P-man said: Was this city built on rock & roll?

You betcha. Cuz the city is the amp.


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