Attack control

[Saturated]

Hi all,
Just wondering is there a simple way to add an attack control to a basic booster, ie LPB1?

[patrick398]

What do you mean by attack? That's a term associated with envelopes, not boosters. Do you mean gain by any chance?

[Saturated]

I've seen it on some fuzz pedals. I mean picking response. Not sure but I think I've seen then between Q1 and Q2?
Or am I dreaming?

[anotherjim]

I think it's when a pot is in series with the input as a variable resistor or used in conjunction with the input bias resistors. The idea is to change the input impedance without altering the bias setup too much. A lower input impedance tends to round off pick attack for a smoother fuzz while a high impedance allows more highs and a harsher, apparently faster, pick attack. Most traditional fuzzes have low impedance anyway, and the attack pot is used to raise it.
This only works if the guitar alone is feeding the input, although an unbuffered wah can work well in front of the fuzz with some useful interaction.

For an LPB-1, messing the input impedance with a pot will either be scratchy or noticeably cut input signal level  (a fuzz can usually stand losing some).
To get the effect with the buffer without having to experiment too much, you might try using a guitar tone control setup on the input to the circuit. That is a 250k or 500k pot as a variable resistor in series with a cap (22nF or whatever) to ground. Copy the tone control in your guitar.
Alternatively and closer to the fuzz attack approach, put a pot as a variable resistance in series with the input to the booster. 250k or 500k. The LPB-1 input impedance is a little under 100k, which may already be removing some highs from your guitar if it has high impedance pickups. If it is, turning the resistance higher with a series pot will restore the missing attack. If your guitar pickups aren't affected by 100k, then this mod won't make much difference except as an extra volume control.

[antonis]

Despite it's prefered name, you want to place a frequency depended control between two active items..
(you can't get away with frequency as long as there are rective lements, like caps..)

For a single stage booster, like LPB-1, you may try to place a pot, wired as varibale resistor, across input cap..

Such a configuration creates a High Pass filter with Gain, with -3db cut-off frequency(upper point) at 1/(6.28*R1*C) with -6db/octave slope and a lower-point at 1/(6.28*R2*C)..
where: R1 = Pot resistance value & R2 = parallel combination of bias resistors and h_FE*Emitter resistor and R1..

It actually is a High Pass filter with flat responce beyond two points (upper & lower) and variable attenuation..


edit: Arggg, Jim..

[duck_arse]

.....


edit: Arggg, Jim..

Antonis, the pirate.

[teemuk]

In an archetypal Fuzz-Tone circuit, the "Attack" control adjusts bias point of the first gain stage, therefore gain and overall asymmetry vs. symmetry of clipping in that stage.

It's a different thing than control for input impedance.

Of course the entire term is so subjective that it can mean pretty much anything in different designs.

[Saturated]

Thank you all. I will experiment with this.