boosters question

[nero1985]

hey guys i wanna build a boost pedal but it doesnt have to be a 10 or 15db high gain or anything im just looking for a full range boost to shape my Clean sound a little bit, i was thinking about the purple peaker, what do you guys think??? is it worh building it for clean sounds? or does it distort, i built a AMZ mini booster but it was too dirty for clean sounds, whats your advice? LP

[Arn C.]

Have you thought about AMZ's Dual Booster?  You can build it as a single boost.  Super clean with high boost capabilities.  Email me if you need the files. 

arn.conklin@ametek.com

Peace!
Arn C.

[vanhansen]

I would think that for what you're after, rather than a booster on the clean sound that a buffer of some sort would do the trick.  Maybe the IC or Discrete Buffer from GGG would add some sparkle and a mild boost as well.  They're both small parts count.  Wouldn't hurt to try either one out on the breadboard.

[d95err]

Try the AMZ Mosfet Boost. It's crystal clean and you can also use it as a unity gain buffer.

[burnt fingers]

Try the clean mosfet boost from this page. I buile one and am very happy with it.  (By the way, this is not my site, I just happened to find it a while back and found some worthwhile stuff on it.)
http://www.kilback.net/homebrewtweaks/pedals/pedals.htm

[Satch12879]

Simple non-inverting amplifier based around a good low noise audio op-amp.  A little high and low end filtering, tailor the gain via a pot in the feedback loop to your exact specs, and call it done.

Been working on one off and on; someday it'll be finished...

[mac]

A fet booster is very simple. I built one with a BF245A, using a 1M at the gate, around 10k at the drain (or a 20k trim to get Vd=4.5v is better) and 1k pot at the source. Input & output coupling capacitors 0.1uf. The bypass capacitor is up to your taste. Around 0.1uf you'll get some treble boost, and at 1.0uf - 10uf full boost. You may choose not to use the baypass cap.

mac

[brett]

Hi.
Like Mac, I reckon JFET boosts have excellent qualities.  They also give you about 1M of input buffering, and only a few k of output impedance.  Try 6.8k on the drain and 2.4k on the source for a subtle 3dB booster, or 4.7k and 2.4k for an almost imperceptible boost.

You could use the stratoblaster pcb etc over at general guitar gadgets and leave out the capacitor that bypasses the source resistor.
cheers

[d95err]

For a really clean boost, you need a booster that varies the actual gain of the circuit, not one that boosts the signal a lot and then uses a volume pot to bring the level down again. If the actual gain is variable, you can always push the signal to the headroom limit, regardless of the input level. With a fixed gain circuit, there will almost always be distortion unless the signal level is very small, or if the voltage used is high (e.g. 18V or more).

The AMZ Mosfet Boost and a simple opamp gain stage with a pot in the feedback loop are variable gain circuits. Most other boosts suggested here are fixed gain boosts.

In conclusion, it's a matter of taste of course, but to get a really clean boost, you need variable gain.

[brett]

Hi.

If the actual gain is variable, you can always push the signal to the headroom limit, regardless of the input level. With a fixed gain circuit, there will almost always be distortion unless the signal level is very small, or if the voltage used is high (e.g. 18V or more).

Both the simple JFET booster and the Stratoblaster that I mentioned above have fixed gain without distortion (as do most boosters).  Their low gain (about 3 and 10 to 15, respectively) ensures unlimited headroom for signals from normal pickups.  (even 300mV p-p and a gain of 12 results in only a 3.6V p-p output signal.)
cheers