varitone

[Shaggy]

how can i construct a varitone myself? cos i thought i would be pretty need to thin out my sound on command(and more knobs looks flashy )

[lovekraft]

Here's the schematic:

Varitone Schematics (from BlueGuitar.org)

Just get a 1.5H choke, a rotary switch, and a handful of caps and resistors, and throw one together. Or you can get one already assembled from our own Big D Guitars - he uses ceramic caps for vintage mojo, not my choice, but for $40.00, you can't really fault it.

You can use a Mouser mini transformer (42TL021) primary for the choke, and poly caps, metal film resistors, etc. for a nice clean quiet modern sound, or get an old radio choke and use those ceramic disc caps and carbon comp resistors for maximum oldschool magic (and noise).

Torres Engineering also offers their "Famous Guitar Kits" version, and of course, you can get a Gibson, if you're willing to part with a lot more cash. HTH

[Stalefish]

I was thinking of doing the same thing myself but experimenting with all those cap values didn't really appeal to me.. If you try it, do tell us how it went!!

[ansil]

the same thing is in the craig anderton book, very usefull if you do it right you can add a switch in there to make it a feedbacker. well it requires a little extra doing.. but basically. if you put in a couple of transistors or a dual opamp you can switch it to ground or to feedback the resonant freq..

[bigdguitars]

When I started building my switches, I went through 200 some odd different caps, its actually a lot of fun to see what caps sound better clean and distorted, but I was un-employed and had plenty of time on my hands.

I never like mylar caps, but thats what every one usually uses.

if you are going to play around the old orange drop caps sound great, but I could not fit that many on my switch.

The varitone is a cool mod to play around with, don't go to radio shack buy from mouser or newark electronics.

rockon

[Shaggy]

thanks, i hope i wire it correctly

[perhellion]

Hi,

I'm a little confused. I thought a Varitone was basically a "sampler" of various caps like those found on tone controls. Basically each switch position would be the same as if you soldered a cap of a given value on the tone control and then rolled the tone all the way off. Essentially, that is what happens -- BUT what does the choke (inductor) do? It seems that even if no capacitor is selected (the Big D one has a "bypass" setting), the inductor is still in the circuit, so how is it bypassed? How is 1.5H the "magic" value? (I'm only familiar with inductors as used in speaker crossovers, and they come in mH values, so 1.5H sounds big). Finally, long ago, I ordered a Varitone kit from Torres, but I never got around to trying it, but I don't remember seeing anything that looked like an inductor in the kit. Maybe someone has a pic of a 1.5H inductor?

Thanks

[lovekraft]

If you bought the Torres kit, you'll have a mini-transformer (probably the one i mentioned earlier) in the package. The primary coil is used for the choke. As for the values, there's nothing magical about 1.5H, it's just what Gibson used, along with 1nF, 3nF, 10nF, 30nF and 220nF caps, and that range seems to be most useful for guitar. The bypass position disconnects the whole unit from the ground, every other position runs a different cap in series with the choke/inductor to ground, giving you a notch filter response at the output. The resistors are there to drain off any DC potential stored in the caps so it won't "pop" when you switch it.

[bigdguitars]

the inductor is the little thing that is blue and has the three wires per side sticking out. One side is marked P for primary, the other side is not marked.

The inductor is pulled out of the switch on the bypass. the way the switch works is in parallel to the system, so when you are on the bypass mode, the switch is connected to nothing.

[perhellion]

I dug out the kit, and the key word is "mini". The mini transformer is there, but it's way smaller than what I expected, so easily overlooked. (Mouser, same part # as above) Is there anything special about the rotary switch? I can see it as being harder to use than, say a Strat-type 5 way. Could I wire it up with a five way? (I realize, of course, I'd lose one cap, as there are five and a bypass) It seems the this is also what the Snarling Dogs Very Tone pedal is, so could I wire this up as a pedal instead? Since it is just hooked to the ground, I wondered if it would work in pedal form.

Thanks

[lovekraft]

Yes, a 5 way (or any other switch) will work fine - you could also use a 5 way for the cap selector and wire a push/pull pot to bypass it. And yes, this is basically what's in the Snarling Dogs box, with an added bypass footswitch and a preamp. If you're going to put it in a pedal, you might want to consider adding a buffer or a preamp to offset any signal loss in the circuit.

[perhellion]

Lovekraft,

Any links to schematics or other people on the internet that might have made such a pedal? (Perhaps just getting the Snarling Dogs pedal is the way to go.) Do you think the Varitone (minus any kind of preamp) would work in a seperate box right at the output jack? (Like the old Armstrong effects; the compressor was called the "Orange Squeezer") The reason for going to this extra trouble is to be able to try the Varitone with several guitars, without actually putting extra holes in them.

Thanks

[lovekraft]

If you're gonna put it that close to the guitar (Dan Armstrong style), it probably wouldn't be any different than installing it inside the guitar so long as your box is shielded - you might want to slap a source follower on the output to keep your cable from loading the circuit and losing more high-end:

Or you could use any simple preamp/booster. If you're going to use the illustrated follower circuit anywhere other than first in line (direct from the guitar), it's a good idea to add a coupling cap in front of the input; another .22uF will work fine. You can use just about any common N-channel JFET in place of the J201. Or use Jack Orman's MOSFET booster, another simple transparent gain stage/ buffer. Slap one of either on each end of the circuit, wire in a bypass switch, and you got a stompbox! If you need more specific info, gimme a shout.

[perhellion]

One thing I'm now wondering - how is the varitone different than an EQ? Say you place the EQ first thing in the output chain. Then find one of the frequencies the varitone effects and "cut" by the amount the vaitone would (All these frequency and db values are listed somewhere online). What would be the difference in the sound done with the EQ and the one done with the varitone? I realize the varitone is cheaper and more simple, but for someone like BB King, for example, (I don't think he adjusts the varitone but sets it to one setting he likes) why not run the signal through an EQ, through the distortion and effects (if any), then through another EQ, and forget the varitone entirely?

[lovekraft]

  What would be the difference in the sound done with the EQ and the one done with the varitone?

The varitone is a fairly tight (narrow band) filter - you could do it just as easily with active parametric EQ, but, as you pointed out

...the varitone is cheaper and more simple...

And the battery never goes dead.

[ansil]

of course another thing to look at is if you want something alittle more flexable than just the cut feature of the nothc. you can improve on this with a simple dual opamp and a couple of caps and resistors to set it up to make it cut or boost. personally i like this option as i can now boost my 1k for solos and such or cut it for rhythmn.

and it only takes like 15 minutes longer to do this than the original circuit. 15minutes for that much flexabliity.. i am in..

[perhellion]

Ansil,

Your idea sounds good, but for us with limited electronics knowledge, exactly what do you mean? Pics or schematics would be great.

[cr_XD]

i think he means something like this

the image, btw

[ansil]

Ansil,

Your idea sounds good, but for us with limited electronics knowledge, exactly what do you mean? Pics or schematics would be great.

well atually the pic shown above there in the link. is for a simple one fet amplifier for say a piezo system and it could be used but i was thinking of say a dual opamp..

http://www.schaltungen.de/datenblatt/daten.../LM/LM6264N.pdf

there is a pic on there of the basic pinout of a dual opamp..

pin four is - pin eight is V+

you need to have a voltage bias which is roughly half of the supply voltage that or use two batteries to obtain the negative and positive source.

the vbias.. again half of V+ will go through an aproximate 1M resistor.. into the third pin of the chip.. from pin one to pin 2 you need a 100k resistor from pin two to a capacitor we need a 15k and a .1uf going to ground.

we take the signal of the guitar and go into a .1uf capacitor into a 10k resistor into pin three.

from there we take pin 1 and apply a .22uf capacitor and then we go into the varitone. circuit.

we take the vary tone circuit. and put a switch on the bottom of the depth pot to either connect it to ground as shown in the schematic or makeit feedback into the guitar signal. ie the switch will move the filter into the 6th pin of the dual opamp.. from the 6th pin to the 7th pin we put a resistor that is 3 times higher than the pot value of the varitone. so if its a 10k pot (as in the craiganderton one like i have.) then we need form 30-50k ressitor between pins 6 and 7. pin 5 connects to the vbias directly no resistor like the pin 3. we then take pin7 and connect it to a .22uf capacitor and go inot a 100k pot and take the pots 2nd lug as output to our jack.

ie like this.

[gnd]***************************[pin 4]

[gnd]***[.1uf]*****[15k]**********[pin2]***[100k]***[pin1]

guitar*************[.1]***[10k]***[pin3]

[V+]****[1meg]*{this is vbias}*[1meg]*********[pin3]

[gnd]***[1meg]*

[gnd]****[10uf] *******[pin 5]

[pin 1]*****[.22uf]*****[varitone circuit]

[pin 1]*****[.22uf]****[pin 6]

get the idea.. hope that helps i am not at a computer i can draw at..

[lovekraft]

If you're going to use active electronics, I'd replace the inductor with an opamp gyrator in the interest of lower noise and drift. Basically, you're making a switchable one band graphic EQ, so that would be your jumping-off point.