Can this Fender Volume/Tone Pedal Be Modified To Not Suck? (schematic & guts inside)

[Phil O'Keefe]

This is a bit of a zombie thread, but . . .

 

I got an orignal Fender tone/volume pedal a month ago. I lent it to a friend because I'm focussed on slide right now and want to nail my intonation and vibrato etc before adding another analogue complication. The little time I spent with it suggests that it's a very expressive musical tool: cleverly designed and well-made. I've asked for it back and will give a report in good time.

 

An answer to the tone-suckage issue. Perhaps if I decide that this is a permanent part of my setup, I should install a switch on my tele that bypasses the guitar's tone and volume circuits. Given that the pedal is basically the same circuit moved to a pedal, the net result won't suck tone at all. Right?

 

Well... no. Not really. It's still going to "suck tone", just like the volume and tone controls in the guitar do. It just won't be the same / as much as the combination of the duplicated controls (in the guitar and in the pedal) give you.

 

Try this for an experiment: connect the output of your pickups straight to the output jack of the guitar, and bypassing the onboard volume and tone controls. I suspect you'll immediately notice a stronger, more robust sound.

 

[pogo97]

 

Well... no. Not really. It's still going to "suck tone", just like the volume and tone controls in the guitar do. It just won't be the same / as much as the combination of the duplicated controls (in the guitar and in the pedal) give you.

 

Try this for an experiment: connect the output of your pickups straight to the output jack of the guitar, and bypassing the onboard volume and tone controls. I suspect you'll immediately notice a stronger, more robust sound.

 

I get your meaning. Of course (almost) everyone is willing to accept the degree of tone loss the standard tone controls cause -- accept it as part of the design of the guitar. My point, I guess, is that you would be transferring about the same amount of loss to another location, hence no net loss and probably less tone change than draining through all four pots in parallel. Myself, I tend to keep the guitar's tone knob somewhere around 3 or 4 -- where it starts to enter phoneme territory -- so a bit of tone loss may be irrelevant. But I'd be curious to hear.

 

Back to the actual pedal, the cleverest part to my eye is that the pivoting plate is supported near each end by ball bearings in curved channels. Very simple and very strong. I sometimes wonder if we are losing the mechanical intelligence the best designers had in the last century.

[Phil O'Keefe]

 

Back to the actual pedal, the cleverest part to my eye is that the pivoting plate is supported near each end by ball bearings in curved channels. Very simple and very strong.

 

It looks like a really clever design.

 

I sometimes wonder if we are losing the mechanical intelligence the best designers had in the last century.

 

Maybe, but I doubt it. Each generation learns from and builds on what the ones before it came up with. But we are more of a disposable society now, which doesn't bode well for them building well-designed, long-lasting products.

[1001gear]

back to the Fedner pedal, wouldn't a treble bleed thing work?

[WRGKMC]

^^^ Depends on the pot taper. Its got a band pass cap in it already so adding another cap is no different then changing the existing caps value. making it sound brighter will only kill more volume and roll more bass off. It doesn't add treble it just gives that illusion.

 

With a passive pedal like that its not just a capacitive resistance issue when you ramp the volume down and add all that resistance across the pickups, you get a drop in signal gain too which affects your string touch. The Fender uses two pots in series which is even worse then using one.

 

I do own a passive stereo volume pedal which is probably the same quality as the Fender. Its got an extra pot on it for setting a minimum volume level which is kind of nice if you're switching from lead to rhythm. It sucks tone and gain too.

 

If you have to use a passive pedal using a booster pedal to makeup gain is your only real option.

 

If you're going to spend that money, I'd simply dump that pedal and get something better. Morley is by far the best volume pedal made. You can get one used for under $50. They don't use pots so they don't wear out. They use optical sensor/photocells instead. The pedal simply uses a shutter to block how much light is passing and as the light level goes down it reduces the conductance in a transistor in a preamp circuit. The preamp is super low noise and linear so your guitar signal maintains its quality and clarity with no tone losses and with the pedal full on there's no volume loss. The differences are literally night and day. Cranking the pedals is like turning your amps volume up and down.

[pogo97]

So, what is the actual effect of the pots in your guitar when they're at 10? That would be a steady drain across 125k for two 250k pots in parallel. (adding the tone/volume pedal would increase that drain to 62k ohms)

 

Does it simply reduce the signal? Does it limit headroom in some way? Or does it limit or alter some frequency range? I'm sure it's complicated, but "sucks tone" isn't very precise.

[WRGKMC]

Pots at zero is a dead short between the hot and ground wires so you get no signal from the pickups. Sometimes crappy pots will bleed a little but there should be no sound.

 

Fully open at 10 on the knobs lest most of the pickup signal through. The only grounding is through the pots maximum resistance. If its a 500K pot you have whatever signal can make it through that resistance which is virtually nothing in most cases.

 

Many analog pots taper the treble response down before the bass as the signal gain is reduced. There's a bunch of reasons for it. The easiest to understand is to simply plug in and turn it down and you hear it happening. If you plug into a frequency analyzer you can see the effect.

 

If you want to understand why in detail it deals with impedance matching to the amp. The amp produces full fidelity when its being fed the correct signal strength. A Pot adds DC resistance to an active impedance circuit and it isn't very good at maintaining AC impedance. Its what you'd call - Good Enough - to get the job done. Musicians use the effect to their advantage and actually prefer the treble roll off for rhythm when turned down ( and treble boost for leads at full volume for leads)

 

There is no real headroom loss (another term for reduced dynamics) because there is no compression involved, simply a signal strength variance and tonal coloration which can be overcome by other devices in a signal chain, at least until the signal is attenuated down to the point where the amplifying devices can no longer function and/or you're boosting more noise then signal.

 

With weaker pickups you can add a bleed capacitor which allows treble frequencies past as lower frequencies are attenuated. This is common on single coil pickups using 250K pots because they darken in tone quicker as the pots turned down. Another way is to use 1M pots with a non linear taper which tend to maintain a better frequency response when turned down. Of course the best solution is to use on board active electronics to maintain fidelity at any volume.

 

Bypassing the volume pots on a guitar with a switch can give you a little boost in gain and treble. Its not usually very much and the question comes down to this. You can install zero load pots which disconnect when you turn the volume up full. You can convert regular pots into no load pots too. You can cut the trace so when the sweeper goes past the cut the volume bumps up, or you can put a dam of nail polish on the end of the pad which acts like an insulator and lifts the sweeper contact off the resistance pad when you turn up full. This may be preferred over drilling a hole for a switch or installing a push pull pot.

 

The question comes down to this - How much gain and treble is enough? Loss of gain can affect your playing. Strings become dull sounding and you can only get so much volume digging into the strings hard. So long as you have the right dynamic range and it sounds good that's usually all you need. Too much gain has its issues. You may not want to hear that much pick attack and it can be difficult to play clean parts. If you have allot of tone suck in your pedal chain it might be enough to get some of the loss back, but its allot of effort to compensate for a crappy pedal a crappy pedal.

 

I did all this stuff back in my experimental days. I thought it was cool at the time but you realize guitars are perfectly find stock. If you need brighter tone you have a knob on the amp called treble - turn it up. If you need more gain - you got a knob that says gain? Turn it up.

 

If you have a crappy volume pedal that sucks the tone and gain down making for a wimpy signal - there's an excellent fix for that. You open the window and give it a good heave.

 

Don't waste time with that piece of junk if there's a much better solution that doesn't cost much. Unplug it from your chain and use it as a door stop or give it to some other sucker that doesn't know any better.

 

Then you take the money you'd waste trying to boost your signal , bypassing pots, EQ, Buffer, booster you only use because of that crappy pedal and buy yourself a quality volume pedal that doesn't tone suck. Problem solved and you save a whole lot of money in the process.

 

I did a quick look. This ones $50. If you subtract the $25 for that passive pedal wasted this pedal would only require an additional $25 and it would last you a lifetime. https://reverb.com/p/morley-volume-p...g&hfid=3829415

 

 

 

 

I think I paid $40 for a volume/wah pedal so I had both in the same unit.

If you want to spend a little more they make them with a volume/drive/wah/ echo/chorus and tremolo combinations which cuts down on pedal board real estate and weight. Quality stuff too, solid metal and they don't wear out. The older silver ones like this https://reverb.com/item/3744135-morl...us-1996-chrome used small light bulbs instead of LED's. You'd have to change them every 10 years or so. The black pedals are LED's and are maintaince free

 

 

[onelife]

Another way to look at loading of a magnetic pickup is to apply Ohm's Law.

 

A guitar pickup generates an electric current and a tube amplifier is voltage driven.

 

To create the voltage, the current from the pickup passes through a resistance and the voltage across that resistance is the product of the voltage times the resistance. Low resistance = low voltage.

 

Since the ammont of current generated by a guitar pickup and the way the current reacts to resistance is frequency dependant, higher frequencies are affected more by the load than lower frequencies.

[pogo97]

Got the pedal yesterday. Something was certainly not right -- it sucked about 5db (that's a guess -- a lot) off the signal and the tone control also affected the volume.

 

1) switched where I plugged in and plugged out (in and out aren't marked) and that fixed the tone control volume suck

2) opened it up and, with both volume and tone pedal positions in "10" position, turned the pots to be also be in "10" position

3) suck-o gone-o

 

There may still be a bit of volume loss, but not enough to tell while switching cables and listening. One pot was a bit scratchy, but that's gone with a little use (good thing, the pots are sealed). The tone control operates like a tone control, so if I want "wah-wah" I have to focus in the phoneme spectrum and sweep fast and maintain modest expectations. On the other hand, it's nice to be able to adjust tone while I'm picking with my right hand. And, as a volume pedal, it's very nice -- heavy, smooth, nice sweep. Anyone wanting to use one of these as a platform for a dual expression pedal would have acres of room to put stuff inside. I'll post a video in the next day or two.

[pogo97]

Here's a demo:

 

http://home.cogeco.ca/~ashleygifford/fender_volume_tone_pedal.mov

[lsjmusicco]

So I have a slightly off topic, but still related to this pedal. I have a one sitting on my bench and I cant seem to get the string setup right to where it just kicks itself back to 0 "heal down" thats not how this works I would assume, didnt get it in working condition, but any help/ pictures would be greatly appreciated. I apologize from deviating from the conversation. But I cant seem to find any info on how to string this volume pedal anywhere.

 

Thanks