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Does Varitone cut or boost midrange?

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dheylen_2000@ya

Nov 9, 2010
23
0
#1
I have a stack knob jazz bass which I would like to mod as follows:

- Stack knob for vol/vol

- 3 or 4 position varitone (1st position = bypass)

- push/pull 'blend' pot to switch between series/parallel wiring & the pot sweeping from pure varitone signal to an equal blend between varitone & straight pickups.

I still have a few questions on this but one thing has got me really stumped. The descriptions I've seen of the varitone circuit describe it as a midrange notch cut. Every circuit diagram I've seen shows the selectable cap array wired in series with the inductor and then dumping to ground The varitione itself is wired in prallel with the pup output, like normal tone controls.

With the hi-pass caps iand the lo-pass inductor going in series to ground, wouldn't this result in a mid-range boost at the jack? To get a mid-range cut, wouldn't the varitone output have to go to the jack rather than to ground?

Can someone please enlighten me as to what I'm missing?

thanks for any help on this.
 
#2
If memory serves, the varitone circuit is just a finite number of capacitors hard-wired for tone - almost like a set number of tone presets for the basic passive tone knob.

A capacitor wired in parallel obviously creates a simple RC low-pass filter, so it cuts the high end. However, as you've picked up, there is a bit of some mid action happening. There is a slight mid hump that forms depending on the capacitor value. It's very subtle, and may be slightly unnoticeable, but it's there.

So I guess the proper answer is that it boosts it, but not much. You can't really boost any frequencies without the use of active electronics.
 
#3
Some Varitones use inductors as well as caps, allowing much more variety than just different amounts of "tone rolloff". They can be designed to cut OR boost the mids. To be technically clear, the "boosting" is in the form of (a) rolling off highs and lows a bit, resulting in what sounds like a boost in the mids; and (b) a resonant peak which actually does boost the level at that peak point a bit.
 
#4
bongomania said:
Some Varitones use inductors as well as caps, allowing much more variety than just different amounts of "tone rolloff". They can be designed to cut OR boost the mids. To be technically clear, the "boosting" is in the form of (a) rolling off highs and lows a bit, resulting in what sounds like a boost in the mids; and (b) a resonant peak which actually does boost the level at that peak point a bit.
Click to expand...


There are multiple varitone circuits? I was under the impression that it was proprietary and a capacitor-only design.
 
#5
A varitone, in most cases, is simply a rotary toggle switch that selects between different values of capacitors, placing the selected capacitor parallel to the signal, with or without a tone pot to vary the amplitude of the cut. The change in capacitance moves the cutoff frequency up and down. The frequency cutoff can range from treble down to low bass, depending on what values you choose.

If you are trying to boost the mids, you will need to have a resonant circuit with an inductor and capacitor, tuned to resonate at the desired frequency. Calculating this frequency can be tricky, as it's going to vary with the LCR of the pickups.
 
#6
FunkMetalBass said:
There are multiple varitone circuits? I was under the impression that it was proprietary and a capacitor-only design.
Click to expand...
The word "Varitone" technically is a proprietary name belonging to Gibson, and their design uses an inductor:

Invalid Link Removed
[Invalid or Expired Link Removed]

It is a variable mid scoop. The capacitors select different frequency ranges of scoop.

However countless people/brands have been making other versions of this sort of rotary-switch tone selector ever since Gibson put theirs out in the 60's, and the general public calls it a "varitone" just the same way they call any Band-aid-like thing a Band-aid.
 
#8
This:

bongomania said:
Some Varitones use inductors as well as caps, allowing much more variety than just different amounts of "tone rolloff". They can be designed to cut OR boost the mids. To be technically clear, the "boosting" is in the form of (a) rolling off highs and lows a bit, resulting in what sounds like a boost in the mids; and (b) a resonant peak which actually does boost the level at that peak point a bit.
Click to expand...

plus this:


bongomania said:
The word "Varitone" technically is a proprietary name belonging to Gibson, and their design uses an inductor:

Invalid Link Removed
[Invalid or Expired Link Removed]

It is a variable mid scoop. The capacitors select different frequency ranges of scoop.

However countless people/brands have been making other versions of this sort of rotary-switch tone selector ever since Gibson put theirs out in the 60's, and the general public calls it a "varitone" just the same way they call any Band-aid-like thing a Band-aid.
Click to expand...

=

+1 !
 
#11
Birdsongs use a 6 position Varitone controller made by Torres Engineering. It has a bypass and 5 tonal settings. I don't know the technical side of this but to my ear the tonal goes from very bright to very low and deep with each position.

Quote from the Birdsong website on this:
"From the first setting (bypass), the next few will cut the high frequencies at increasingly lower points resulting in funky midrangey tones. The last two are very deep sounding; with some sonic tweaking on your amp these could provide interesting main tones, huge sounding with distortion or great for reggae or dub clean. The varitone can also be modified by those with electronics experience, a handful of capacitors and a soldering iron. This may, however, void the warranty on certain electronic components."
 
#12
You actually can get a small boost passively. An example is a passive tone control. When it's all the way off, it gives a small resonant boost in the bass frequencies.

Another example of a passive boost are the Villex tone controls which probably use a transformer to step up the signal a bit.

But these are by no means as much boost as you get with an active system. Many preamps use a passive tone stack which causes a lot of insertion loss, so you need an active stage to boost the signal back up.

Varitones also produce some signal loss going through the circuit.
 
#13
greggster59 said:
Birdsongs use a 6 position Varitone controller made by Torres Engineering. It has a bypass and 5 tonal settings. I don't know the technical side of this but to my ear the tonal goes from very bright to very low and deep with each position.
Click to expand...

It's very similar to the Gibson circuit. It uses a small signal transformer as an inductor.
 
#14
SGD Lutherie said:
You actually can get a small boost passively. An example is a passive tone control. When it's all the way off, it gives a small resonant boost in the bass frequencies.
Click to expand...


Where does the energy for the boost come from? TINSTAFL In a passive system, there's only one source for energy and that's the pickups themselves. Unless: there's some conversion of the energy from the high frequencies to boost the lows (doubtful in this simple system), you're converting matter into energy (even more doubtful), or you've got a flux capacitor in your bass, this isn't possible. If you hit a resonance, it means the system is storing the energy because it is being released or dissipated more slowly than it is being added. Under those circumstances, the signal level could grow over time giving the illusion of a boost, but that's not boosted in terms of adding new energy.

The transformer would increase the voltage but at a loss of current.

Either that or you've tapped into zero point energy due to the casimir effect between the pickups.
 
#15
SGD Lutherie said:
...

Varitones also produce some signal loss going through the circuit.
Click to expand...

I'm sure that's entirely true academically, however it should be noted that in typical varitione/multi-network capacitor/inductor circuits any signal loss (other than intended frequency-dependent attenuation) is negligible if not undetectable by normal human hearing. In practice, I use my own custom 'varitones' regularly in the studio. Under the more critical scrutiny of professional recording sessions, I've never had to make a gain or volume adjustment when engaging my passive tone circuits.
 
#16
bongomania said:
The word "Varitone" technically is a proprietary name belonging to Gibson, and their design uses an inductor:

Invalid Link Removed
[Invalid or Expired Link Removed]

It is a variable mid scoop. The capacitors select different frequency ranges of scoop.

However countless people/brands have been making other versions of this sort of rotary-switch tone selector ever since Gibson put theirs out in the 60's, and the general public calls it a "varitone" just the same way they call any Band-aid-like thing a Band-aid.
Click to expand...

Ah, so it's one of those Coke, Kleenex sort of deals. Gotcha. Thank you, good sir.

[Invalid or Expired Link Removed]
 
#17
Rob22315 said:
Where does the energy for the boost come from? TINSTAFL In a passive system, there's only one source for energy and that's the pickups themselves. Unless: there's some conversion of the energy from the high frequencies to boost the lows (doubtful in this simple system), you're converting matter into energy (even more doubtful), or you've got a flux capacitor in your bass, this isn't possible. If you hit a resonance, it means the system is storing the energy because it is being released or dissipated more slowly than it is being added. Under those circumstances, the signal level could grow over time giving the illusion of a boost, but that's not boosted in terms of adding new energy.

The transformer would increase the voltage but at a loss of current.

Either that or you've tapped into zero point energy due to the casimir effect between the pickups.
Click to expand...

Winner winner, chicken dinner! :D
 
#18
Oh boy, I guess Lug & Rob22315 have it all figured out already. ;) Awaiting better engineers to correct them... (while I know it's possible & have read plenty about passive boosting- I'll let someone with a better handle on the correct lingo explain it...)
 
#20
Resonance is a feedback-like condition where a specific frequency will amplify itself. The effect is not perfectly instantaneous, the same way feedback through a speaker is not instantaneous; however the process begins at the speed of light, and its slope of increase depends on the resonance of the circuit (just as the amount of acoustic feedback depends on how close your mic is to the speakers).
 

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