Tone Bender building for dummies?

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Re: Tone Bender building for dummies?

Post by Wonks »

Well there were certainly 5 full revisions of the Tone Bender design, Mks 1, 1.5, 2, 3 and 4 (Mk 1.5 is an unofficial name but it is a definite design variant). The Mk 4 is basically a Mk 3 in a different case but there were some later resistor and cap value changes.

And some of those deigns will have been modified to work with the specified circuit diagram transistors rather than the originals used. But yes, there are always likely to have been some 'close enough' substitutions made if parts ran out.

And some of the 'rebranded' Tone Benders such as the Marshall Supa Fuzz had 'near identical' circuits to existing Tone Benders, so probably the same layout with a few small component changes for a very slightly different variation in sound.

It was in the 70s that you started to get variations of the circuit design using different transistors, presumably as more reliable transistors came out and the original types became scarce. the support circuitry presumably had to change slightly as well.

And the Supa Tone Bender I had (introduced in 1973) was in fact a Rams Head Big Muff copy less a few decoupling components (I never knew that until now).

And the Sola Sound Fuzz was V3 Big Muff circuit!

So you can't blame the Chinese for starting the pedal cloning business!
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Re: Tone Bender building for dummies?

Post by SecretSam »

Wonks wrote: Yes, if they'd made a generic Tone Bender Mk 2 design, with each one sounding a bit different, then $350 would have been far too much money, but it 's not a generic design, it's a very specific design, and one that did involve a lot of R&D.

Hm. Willing buyers, willing seller. Fair enough.
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Re: Tone Bender building for dummies?

Post by SecretSam »

Right. Next stupid question:

Would it be a good idea to put a bias control on each transistor, not just one? So two bias knobs.

(Current thinking on labelling:

Volume= attention-seeking
Fuzz= fibrillation
Bias 1 = judgement
Bias 2 = prejudice

Now I have the wording sorted out, that just leaves the soldering. And the layout. And the component values.)
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Re: Tone Bender building for dummies?

Post by Folderol »

SecretSam wrote:Right. Next stupid question:

Would it be a good idea to put a bias control on each transistor, not just one? So two bias knobs.

(Current thinking on labelling:

Volume= attention-seeking
Fuzz= fibrillation
Bias 1 = judgement
Bias 2 = prejudice

Now I have the wording sorted out, that just leaves the soldering. And the layout. And the component values.)

Doubtful, most of the others are just emitter follower buffer stages - but which design are you going for? They are all somewhat different :shh:
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Re: Tone Bender building for dummies?

Post by SecretSam »

I thought the Fritzing one. Because it has the optional mods of the one before it, plus a bias knob.

I have no idea really how else to choose.

Oh, and the printing is nice and clear.

It seems to use TRS sockets, which I don't really understand ....
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Re: Tone Bender building for dummies?

Post by Wonks »

Bias pots are almost always set and forget items. You wouldn't want to have them easily accessible for twiddling. E.g. you don't have a big bias adjustment knob on the front of a valve amp, if there is one, it's hidden away.

You'd adjust the bias to achieve a certain output for a certain input for each transistor and there's a very small range of resistance either side of that setting that would be workable. You'd need to build the circuit, find out what the resistance value was and then replace yoiu variable resistor with a fixed resistor at a value at the lower end of that range, and have it in series with a pot that had a value that spanned the extra adjustable range e.g. if the useful bias resistance range was 4.75k to 4.85k, then a 4.7k resistor and a 100 ohm pot in series would work. I have no idea what values you'd need, that's just to try and show the principle.

It could be done. but you'd have to fully understand the circuit by building it first to find out what non-optimal bias settings did to the sound.
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Re: Tone Bender building for dummies?

Post by Martin Walker »

Wonks wrote:Bias pots are almost always set and forget items. You wouldn't want to have them easily accessible for twiddling.

Agreed - a multimeter is recommended for setting up the optimum bias in many stompbox circuits where transistor gains vary from unit to unit. It's possible to adjust bias to what your ears prefer, but without a multimeter to check several voltages the chances are that the circuit won't be sounding as originally intended.

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Re: Tone Bender building for dummies?

Post by Martin Walker »

SecretSam wrote:I have in mind to look for an oversized casing in a junk shop, and add spurious controls labelled with words that might just be technical, such as 'mingle', 'fibulate' and 'squirt'.

That approach really appeals to the steampunker in me, but don't underestimate current price points! I'm often amazed at how much the average 'junk shop' (aka antique/curio emporium) is asking for battered old casings.

Also, a grounded metal enclosure makes more sense, as fuzz boxes tend to involve high gain amplification, and are therefor more prone to picking up stray hums.

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Re: Tone Bender building for dummies?

Post by SecretSam »

Wonks wrote:Bias pots are almost always set and forget items. You wouldn't want to have them easily accessible for twiddling. E.g. you don't have a big bias adjustment knob on the front of a valve amp, if there is one, it's hidden away.

You'd adjust the bias to achieve a certain output for a certain input for each transistor and there's a very small range of resistance either side of that setting that would be workable. You'd need to build the circuit, find out what the resistance value was and then replace yoiu variable resistor with a fixed resistor at a value at the lower end of that range, and have it in series with a pot that had a value that spanned the extra adjustable range e.g. if the useful bias resistance range was 4.75k to 4.85k, then a 4.7k resistor and a 100 ohm pot in series would work. I have no idea what values you'd need, that's just to try and show the principle.

It could be done. but you'd have to fully understand the circuit by building it first to find out what non-optimal bias settings did to the sound.

That sounds like a depressing amount of work. What about just including one of those tiny knobs that you adjust with a screwdriver and leave hidden inside the case? Just fiddle until it sounds right, then leave it alone.

You do see fuzzes with bias controls. But they are built by proper electronic geezers I expect.
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Re: Tone Bender building for dummies?

Post by SecretSam »

Martin Walker wrote:
SecretSam wrote:I have in mind to look for an oversized casing in a junk shop, and add spurious controls labelled with words that might just be technical, such as 'mingle', 'fibulate' and 'squirt'.

That approach really appeals to the steampunker in me, but don't underestimate current price points! I'm often amazed at how much the average 'junk shop' (aka antique/curio emporium) is asking for battered old casings.

Also, a grounded metal enclosure makes more sense, as fuzz boxes tend to involve high gain amplification, and are therefor more prone to picking up stray hums.

Martin

I fondly imagined that a metal box works like a Faraday cage. What is this grounding of which you speak?

There are still a few charity shops around here where people drop off junk like old clocks and radios and pans and stuff. If all else fails, maybe a small metal cashbox - which would handily hinge open for changing the battery.
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Re: Tone Bender building for dummies?

Post by Wonks »

Yes, certainly include a trim pot for that purpose.

You’ll probably find that those fuzzes with bias pots have been through a similar process to that I described. It’s not that hard to do. Just set the circuit up on breadboard so it’s easy to change components, work out what the useful adjustable range is and pick a resistor and pot as appropriate. It obviously helps to have a good range of basic components like resistors and caps to hand. Other bits you can order as required.

On the box thing, you were talking about cases, and without being more specific, a lot of those in junk shops will be wooden. If you only meant metal cases , then that’s fine.
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Re: Tone Bender building for dummies?

Post by Folderol »

I made an interesting discovery today. Farnell still sell 1N270 germanium diodes, and seem to have a large stock of them. With all this talk about fuzz, I was reminded of my (ancient) idea for an asymmetric fuzz effect :)
However...
Farnell's minimum order value for free delivery has shot up to £40, otherwise delivery charge is £10 (used to be about £3) :shocked:
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