El efecto del buffer en mi cadena de pedales de efectos

Sí a los buffers y a los efectos de guitarra

Estimados lectores,

Como vieron en la entrada anterior, he instalado un buffer al final de la línea de mis pedales, si bien no tengo "tantos", tengo bastantes más pedales que el promedio de los guitarristas que conozco.

Amigos, la diferencia es IMPRESIONANTE, respecto a no tener un buffer. Los ruidos propios de una cápsula simple o single coils, casi han desaparecido. Magia. Los niveles de los efectos están perfectamente balanceados. Procuren que el buffer sea unitario (1:1).

Siempre me había pregunta ¿Porqué Gilmour tiene poco "ruido"? (los fuzz son ruidosos (Ge, Si) , igual que los flangers; que Gilmour usa en extenso a través de su carrera) ... duuh !!!!, usa buffers entre cada etapa de pedales, es decir, intercala un buffer entre cada pedal. Además de ser todo modificado por el glorioso Cornish, son buffers a tubos, lo que explica la calidez in-between de los efectos.

Pienso que la clave es: pedales con un selector true by-pass y un buffer entre cada pedal.

Trataré este fin de semana, de grabar ambas situaciones, para que compartamos su sonidad, posiblemente, lo haré con cam, y lo subiré a youtube.

No sé si puedo expresar lo radical de la "mejora". ¿Qué pasará si agrego otro buffer por ahí?

Suena MUCHO MEJOR.

Carlos

Looper + Buffer

ISIKE, me ha construido un nuevo pedal, es un Buffer con un loop.

La idea es no agregar los pésimos separadores de señal propios de un delay de pedal.

La señal de la guitarra llega al looper, separa una porción que pasa directo al ampli, y que además está con buffer, por lo que hay mínima degradación.

La otra porción, va al delay, que está al 100%. entonces se suman: la señal inicial (sin delay)+ la repeticiones del delay (sin señal original)


http://microjunkers.blogspot.com/

Yes, another true bypass story...

Every so often, the topic of the virtues of true bypass comes up, and it is always surrounded by lots of questions. One particular question that keeps returning is wether the whole true bypass thing is completely misguided or not, seeing as some players (like Jimi Hendrix) sounded pretty good without it... Some players even seem to rely on the treble loss casused by using a long coiled cable.

But really, true bypass and treble loss due to coiled/long cables are two entirely separate items that need to be looked at separately. This rant - as so many others - started its life as a reply in a thread at Harmony Central's effects forum, and I decided to save it for posterity. I figured I might as well, considering the amount of time it took to put it together... Anyway, back to the topic at hand:

Cable losses
The treble loss associated with curly cords and pedals with the old-style half-assed bypass (old vox wahs, for instance) is well known. Some players even use/used it to their advantage, to tame an otherwise too bright and brittle sound. Albert Collins used to run a Telecaster into a Fender amp with the treble on 10, and with a 100' cord in between it sounded pretty decent. With a shorter cord... ouch. Brian May used the longest curly cord I've ever heard of, and it helped him get his trademark tone (along with his homemade guitar, treblebooster and AC30TBs, of course). It's all in the combination, and how you put your chain together.

But not all of us want to depend on treble loss in the cables, to get our sound. For instance, most people don't run their amps wide open, and would therefore lose too much treble with a 100' cord or spiral cable - enter the buffer. Let's investigate what that thing actually does...

The buffer
We often call it a device that converts the guitar's fragile high impedance signal to low impedance, making it more durable. While this is true to some extent, what really happens is that the buffer disconnects the source (guitar pickups) from whatever follows, by placing a transistor in between them. Very roughly, the transistor uses the power source to create a copy of the source/input signal. The copy is then sent onward, while the original signal is discarded (if the transistor is asked to amplify the signal, it simply makes the copy more powerful). Since the output impedance of the transistor is much lower than that of a guitar pickup, the new signal can travel much easier through the cords ahead. But the source signal is gone forever, though...
Equal gain buffers are generally pretty good at reproducing the incoming signal, though, and when we compare the sound of a 30' cable to the sound of two 15' cables with a buffer in between, the gains (increased treble response and dynamics) associated with the buffer usually far outshine any losses. But keep in mind how the transistor works - it hears a story (the guitar signal), and then re-tells the same story, but in its own voice. Have you ever told someone a story, and weeks later the story comes back to you via someone else? It usually has changed quite a bit, from all the people adding their "voice" to it...

Stacked buffers
Now, ever since the late '70s, the standard for Boss/Ibanez type pedals have been to have two buffer stages, plus a transistor-based switching system. If we only count buffers, and figure that the pedal is bypassed, what happens? Your original signal is lost at the input buffer, which sends its copy/version forward to the output buffer, which copies that signal, and sends it out via the output jack. Now imagine you combine five such pedals in line, all bypassed. Count 'em... You have the input buffer of the first pedal, where your guitar signal is being copied, and then [b]nine[/b] additional stages, all making a copy of a copy of a copy of.... (ad infinitum). With each step, you move slowly but steadily further away from what was your original signal. You might like the changes, or not, but there's no denying that the difference is there.

But what does all this have to do with true bypass and coiled cords, you may ask? Well, while true bypass removes the "stacked buffer" effect, it will also expose your signal to the treble loss caused by long cables. To a certain extent, some of that signal can be saved by using low capacitance cables like George L's or the Klotz GY107 LaGrange. Remember that the treble roll-off Brian May relied upon only happened between his guitar and treblebooster - after that, the signal was low impedance, and not as sensitive to cables anymore. Thus, the most important cable, tone-wise, is the one from the guitar to the first effect (as long as it is active, that is - if it is true bypass[ed], the following cables may count as well).

The art of compromise
To get the perfect compromise - if there ever can be such a thing - you can insert a permanent buffer stage somewhere in the chain (but just the one instead of 10-20 of them), while keeping the other effects on a true bypass diet. That will help smooth out the signal differences when you bypass and activate the TB pedals, since it will always provide a stable low impedance signal, regardless of what pedals are active or not. At the same time, the true bypass switching on the pedals will keep the number of stacked buffers to a minimum. To drive a long pedalboard-to-amp cable, place it last in the chain. To help push through the pedalboard connections (up to the first active or buffered pedal), place it early, but not before fuzz pedals that don't like low impedance signals. This buffer stage can be a dedicated buffer unit (such as the Axess BS2 or VHT Valvulator), or a booster or eq pedal you always leave on. But it can also be just an ordinary Boss/Ibanez type pedal, left in bypass mode. Of course, if you already have a buffered pedal elsewhere in the chain that you keep permanently active, you are already there.

Again, it's all in how you combine the elements - true bypass doesn't solve any world problems, and neither does a good buffer. But if you put them together (in the right proportions), and couple them with a good low-capacitance cable, they will improve your tone and impact quite a bit. Unless you rely on treble loss for your tone, that is, and can't find your sound by simply turning down the treble knob...

http://www.stinkfoot.se/andreas/diy/articles/bypass2.htm

Rz

What are buffers and how are they used?

Buffers are extremely important in a multi-component system. They are often misunderstood and often get a bad rap by those who are uninformed.

In a CAE system, a buffer is a unity gain (input level equals output level) impedance converting circuit. It essentially protects your high impedance guitar output (or any other high impedance source, such as an amps' effects loop send) from being loaded down by the input it is connected to. In effect, it converts high impedance to low, which means subsequent stages are then driven by a low impedance source (the buffer's output). High impedance sources such as your guitar's output (assuming you have passive pickups) has very little current drive capability and it's signal is subject to a harsh environment once it leaves the guitar. You already know the adverse affect a long cable has on your tone. Same thing happens if you pass your signal through a bunch of effects pedals. Even if they have "true bypass" (an ugly, over-used term), each one will suck a little more of your signal along with the cables and connectors, mainly due to capacitive loading of your high impedance guitar signal. The end result is a muffled weak signal that lacks clarity.

But once your high impedance guitar signal hits a properly designed buffer with a high input impedance, the buffer takes over, and uses its higher current capability (remember, its an active circuit that requires a power supply) to drive all subsequent stages, thus preserving your instrument's tone. This brings us to buffer quality.

Buffers come in all types of designs, from discrete transistor, op-amp, to esoteric tube designs. All have their own unique sonic stamp. At CAE we use the op-amp approach. It has served us well for years, is low noise, and is extremely transparent to our ears. Buffers often get blamed for causing an overly bright sound, but we feel if its designed properly, any perceived "brightness" is because now the guitar is not being loaded down by subsequent stages!

Buffers can cause problems, too. There are some effects devices that don't like to see the low output impedance of a buffer. These are typically discrete transistor designed fuzz circuits (such as the Dallas Arbiter Fuzz Face). They react better to the high impedance output of the guitar. In fact, the guitar output, cable and input stage of the Fuzz Face complete a circuit that is highly dependent of those 3 components to work correctly. Fuzz Faces clean up nicely when you roll back the guitar volume control... not so if a buffer is between the guitar and Fuzz Face input. So if you have a pedal board with a Fuzz Face on it , put it first! Other pedals may react the same way. Experiment to see what works best for you. Keep in mind all active pedals (such as Boss, Ibanez, etc...) act as buffers and will impart their own sonic stamp even when bypassed. This is what started the whole "true bypass" (ugh! that term again) craze. See? Too much of a good thing can be "bad". Which brings us to how we utilize buffers in CAE custom switchers. We only use buffers where absolutely necessary.

Typically, in a pedal based system we will not buffer until after the first 4-5 loops, which is usually just prior to sending the signal down to the pedal board (via a long cable run, hence the need to buffer) to hit the wah/volume pedals. Any more than 4 or 5 loops, and the guitar signal may be affected by capacitive loading. So the first few loops is where you would put any impedance sensitive effects. This also means your guitar will go through fuzz, overdrive or distortion pedals BEFORE the wah. We prefer this order because the wah then has a more harmonically rich signal to filter. Try it yourself.

Of course, if a specific order is required, we will do everything we can to make it happen. Buffers are also necessary to drive isolation transformers, since the relatively low primary impedance of the transformers may be detrimental to whatever circuit is feeding it. This is also why amp splitter circuits must be buffered. You can't drive multiple amps with a relatively high impedance source. So there usually is a buffer somewhere in the output stage of your custom switcher. That's usually it. 2 places minimum. There may be more active stages depending on your system requirements.

http://www.customaudioelectronics.com/frequently_asked_questions.htm

Rz