i love the klons buffer, how would I do something like this?

[stopstopsmile]

I am a big fan of the klons buffer, I also like the buffer in the visual sound and the crowther hotcake, hell even the sexdrive has a good buffer.

anyway the klon is the best.  What circuit could I build to make one of these into a stand alone pedal?  How complex is it to make a buffer like this?

Last question, if I want to implement this into a pedal and not use true bypass how would I do that.

Newbie, and I thank you

[aron]

Here you go:

http://www.muzique.com/lab/buffers.htm

[Bernardduur]

The Klon's buffer is a simple IC buffer

[aloupos]

I have to admit those buffers are pretty awesome! 

[Mark Hammer]

Last question, if I want to implement this into a pedal and not use true bypass how would I do that.

The advantages of having a buffered out, even in bypass, are clearly audible in the samples on the CD accompanying Dave Hunter's (otherwise somewhat mediocre) recent book about Effects Pedals.  The samples compare a buffered out from a Visual Sound pedal vs a true bypassed signal.  My guess is the samples were recorded in circumstances favourable to demonstrating the virtues of buffering, but that's okay by me because those circumstances aren't all that rare.

If you read some of the blurb over at Pete Cornish's site, and follow the true-vs-other bypass debate here, you may come to the conclusion that true bypass has its advantages (simplicity being one), but also has its disadvantages too.  The principal disadvantage - that of not providing any way to buffer the effects of multiple cables in series - is overcome by having a single decent buffer stage where the cable from the guitar first hits the pedalboard.  If that buffer is always present, and the guitar signal always passes through it, then it really doesn't matter whether any of the succeeding pedals have a buffer or not, since they will invariably have a low-impedance out which will not "challenge" the next pedal in line.

When pedals were young, designers naive, pedalboards tiny by modern standards, and stompswitches costly, manufacturers used SPDT switches that simply selected whether the output jack would "see" the signal coming out of the effect circuit itself, OR what was arriving at the input jack.  The effect circuit input stage was never lifted out of contact with the input jack, so if the terminating resistor was a smallish value, it remained as a load on the guitar signal at all times.  If you were using a cheap Asian guitar with fairly low-impedance pickups, and one pedal, that posed little problem, but if you had a higher quality instrument with more conventional output impedance, and had several pedals (e.g., wah, fuzz face and univibe) in series, then all the loads from the pedals placed in parallel with the guitar would suck a great deal of high-end away.  As both overwound pickups and bigger pedalboards started to emerge, we saw the arrival of the tone-sucking problem...big-time.

At the most basic level, the solution to this emerging problem was simply to lift the connection between the circuit board and the input jack when the effect was not in use.  A DPDT stompswitch could do both switching actions (input and output) simultaneously.  As Pete Cornish rightly notes, though, (and whatever you may think of his pricing and/or product, do note that he has been at this game since before the problem first arose), unless you have some sort of buffer in place, then all true bypass does is turn a pair of 20' cables into a single 40' cable with all the cable-capacitance issues (read the article in here: http://hammer.ampage.org/files/Device1-5.PDF ) inherent in that.

Keep in mind that no pedal-maker knows for certain where their pedal will end up.  They may advise you where to place it, but they cannot force your hand.  Consequently, if they do not know for certain that a buffer will ALWAYS precede their pedal, what they do is include a buffer, to assure that one will always be present.  In the case of FET-switched pedals like those of Boss and DOD, among many others, there is a certain amount of additional circuitry between the simple input buffer and the output jack.  In the case of other pedals (and I gather the Klon is one of them, since internal pictures show a stompswitch.  VS pedals may well do the same but I've never seen any inside pics of them, so I can't say.  Roger Mayer pedals use something similar.), a switch taps the buffer output directly.  Such pedals essentially uses the same SPDT switching employed by pedals from the 60's and 70's.  HOWEVER, where the vintage pedals would select from either the effect output or the input jack (complete with all loading), the newer ones select from the the effect output OR the buffer output occurring between the input jack and the rest of the effect circuit.  The overall effect pedal always remains "in-circuit", but in a manner that  is completely unobtrusive.  If the pedal is first in line, and the first cable of not especially high quality (and long-ish), a good buffer can make a huge difference.

Quite honestly, I find it hard to say which specific buffer circuit is "better".  They are all quite basic circuits, and bipolar vs FET, op-amp vs discrete, probably makes little difference.  Differences may well be simply the quality of the parts used, or things like supply voltage, or protections against overload (e.g., diodes from the signal to V+ and ground).  Audible differences may be negligible or only evident under certain conditions.  For example, most of us would find any basic buffer thoroughly able to handle a 20' cable to the amp, but not every buffer would necessarily be able to drive a 100' cable snaking around a large concert stage to a backline situated behind the drummer.

So how to design it.  If you have an effect with an input buffer, then it may simply be as easy as rerouting the switching such that the output side of your stompswitch selects between the effect and the buffer.  The challenge is to be certain that what comes after the buffer does not load down the output signal and defeat the benefits of the buffer itself.

On the other hand, if one has an always-on, always-in-circuit buffer as the gateway to the pedal-board, then you should feel free to use true bypass for all your pedals, since what emerges from your pedalboard will always be buffered, whether by the entry-point or by some subsequent pedal.  The nice thing about DIY is since it is predicated on YOUR circumstance and use, you can cut all unnecessary or redundant corners with confidence; you're not building for some unknown client using your product in unknown ways.

[MikeH]

Anyone have any thoughts as to which type of buffer they prefer?  Or more generally opamp vs. transistor?  Obviously, the more transparent the better.  I'm moving ever-closer to a 100% DIY effects rig and I'm going to have to start thinking about buffers soon.

[aloupos]

It looks like the Klon actually provides a seperate buffer out of the pedal.  I guess that could be useful

[frankclarke]

Do we mean booster when we say buffer? A stand-alone buffer isn't very exciting.

[PerroGrande]

Stand alone buffers can be plenty exciting if they prevent tone loss, enable long line runs, etc.  Buffers do not provide voltage gain (in fact, some produce a minor voltage loss).  What they produce is *current* gain.  While the signal isn't "louder" per se, it can travel long cables, leap tall buildings, and hit on your girlfriend with plenty of oomph left over to arrive at your 2KW stack tonally unaltered by its exciting trip...  All of this, while presenting the source (whatever that might be) with a nice, high, input impedance...  That is the "pro" to buffered signals.  The "con" being, of course, that an (another) active component was in the chain.

Preferred buffer type?  Well, I'm afraid that on this questions you may get as many answers as stars in the sky.  It is largely due to personal preference and what one finds satisfactory to their ear.  Op Amps, especially those designed for audio, have distortion and noise specs that thoroughly kick the posterior of almost any discrete design out there.  Yet in spite of this, there are folks who don't like the way they sound.  Discrete stuff, especially simple JFET or MOSFET followers, are small and elegant solutions to many buffering needs and lots of people like how they sound.  I use them extensively, and I'm also a big op-amp fan (no mojo for me, huh?).

I suppose one could add another switch on the input side of a pedal to opt between buffered bypass and true bypass...

[soulsonic]

I like opamp buffers powered by a true bipolar supply = super clean and can drive whatever you throw at it. A good FET input opamp like a TL07x series one is good because it gives a nice high input impedance that the guitar likes.

[Mark Hammer]

Do we mean booster when we say buffer? A stand-alone buffer isn't very exciting.

A buffer doesn't HAVE to be exciting.  All it needs to do is permit all the excitement inherent in one's original signal source be made full use of.

On the other hand, a double-duty circuit isn't such a bad thing.  One of the reasons I like the AMZ MosFet booster circuit is because one can use it as buffer OR booster.  You will note that the gain is set by a single variable resistance in series with an electrolytic cap to ground.  If one places a higher-value resistor between the cap and ground, the circuit serves as a close-to-unity gain high impedance buffer that you can leave on all the time.  If you want to turn it into a booster, all you need to do is reduce that resistance by means of a SPST that patches in a preset resistance in parallel to drop the overall combined resistance.  The nice thing is that by providing an unbroken path between the cap and ground at all times, the cap gets to discharge, so you shouldn't experience any popping.