08 July 2012

Pedal Effects: Order and troubleshooting pedal boards - Part 1


Somed ay, we will have that kind of fever for having a big pedal board, with every kind effect ready to be used in that amazing song that we are going to create some day in the future. .
Some people will finally find a good use for each pedal and will wisely use them along a complete gig and, sure, that people needs a bunch of pedals in their chain, while others will end with one Wah, one Overdrive and one Delay and, will have their job done. Every guitarist walks his way in his tone chase.

But, even having just a couple of pedals we can face several issues. Put an old Wah together with an old germanium Fuzz and we start the tone sucking dance, by example. Even a single Wah or Phaser can be a mess.

This is time to see which kind of issues we can face when setting up our pedal board, which is the "normal way" to arrange pedals and what happens if we change that order.

Don't suck my tone,  please

Well, there are some many ways to go wrong with our tone that, sometimes, it seems better just to directly plug your guitar to the amp and forget all this but, ok, ok, we love pedal effects, right?.
Let see which kind of things are sucking our tone, first.

Cable, True Bypass and Buffers

In a previous entry in this blog, we already discussed which kind of issues are derived from a guitar cable
(see    ) so, I will not repeat that part. Just, think that a cable will roll off more high-end while increassing its real or virtual length.
Pedal effects are their own meters of cable inside. The wires that link their components to produce such an interesting effect are more cable virtually added to the length of cable that links our guitar with our amp. As we increasse that virtual length, we are rolling off more and more high-end frequencies, until the loss can be clearly heard.
True bypass pedals are linking input to output jacks with a very short couple of wires. That also increases the length of our virtual cable but, in way less amount than when the effect is switched on.
A True Bypass pedal isn't routing our signal inside its circuits so, we are saving some issues here.
The drawback is that if we have a bunch of pedals in true bypass mode and long cables between our guitar and pedalboard, patch cables between pedals and between our pedal board to the amp, we are building a really long virtual cable and, that can usually become in a clear lost of high-end frequencies.
That kind of issues derived from long runs of cables (virtual or real) can be fixed with a good Buffer, Line Driver or Booster and, lost of high-end frequencies can be restored with the use of some Treble Booster at the end. But a such a pedals can create other issues with old designed pedals if they are placed in the wrong spot.
Buffered pedals are affecting always to the length of the virtual cable, since the input is routed to the guts of the pedal effect. Since buffers change the relationship between input and output impedances, we can have impedance related issues and, we can have tone sucking issues, when the signal is being affect by part of the pedal's inner circuitry.
Impedance is a very complex thing, and it is from a mathematical point of view also. The Impedance is some sort of mix of a Resistance and a Reactance, where the Resistance is defined by the Real part of the Complex Number, while the Reactance is the Imaginary part of that Complex Number.
You can go so deep as you wanted with the complete physics behind that or, go simpler, as any common guitarist should do.
To make it simply, the impedance for AC current is somewhat the equivalent to a Resistor for DC current.
One ideal pedal effect should have an infinite output impedance and a zero output impedance, to achieve the most transparent tone, preserving the whole frequential content.
The guitar is a mix of an inductance, a resistance and a conductancy that finally delivers a complex signal, with an impedance of around 1 MOhm. Amps inputs are usually prepared to handle this level of impedance. This is usually called Hi-Z instrument level line.
Mics are usually working with way low impedance levels, of around 600 Ohm or less. Same happens to electronics instruments, as keyboards and so on.
So, when there is a high mismatch between the impedance that the pedal was designed for and the impedance that reaches its input, we are facing impedance issues.
Think on a chain of pedals. The first pedal needs to work with an impedance of at least 1 MOhm and, leave a low impedance on its output. Next pedal, should be prepared for a high impedance also on his input. If the input impedance of such a pedal is lower or close to the output impedance level of the first pedal, we are facing impedance issues.
When you start to stack pedals, a good practice is to first hear every pedal alone, to get the signature sound of that pedal. Then it's easier to see if once you insert it into the pedal board, the sound goes to worst.
This is not always an impedance issue but, to be sure, it's a good idea to read the technical specs of each pedal and to draw some chart seen which are the output and input impedance levels for each pedal.
The chain will work better with the highest input impedance pedal de first and the lowest output impedance pedal the last. This is very generic and you will be often forced to reach some compromissed solutions.
At this point, just get the idea that one of the things that can change the order in our pedal board is just the need to troubleshooting some impedance issue.
To use a Buffer or Line Driver, that usually creates a big difference between input and output impedance levels to better preserve the frequential range of our guitar' signal just before a pedal that was designed for a low impedance (like many fuzzes and vintage wahs) can be worst than the tone sucking produced by such a pedals. In that case, the Buffer can work better after those pedals. You just need a buffer in some point on your chain to rearrange the impedance levels. You should find the best spot, when it does its best and makes wrong nothing else.
Batteries, Current Adaptors, Power Supply
When you run all your pedals with batteries, usually, everything is fine. After or before, you will decide that you are expending too much money on new batteries or, that you are fed up of one or more of your pedals running out of battery while you were in that awesome solo (wasn't nobody there to record it? hell!).
And then our monster called Noise comes. One of the main sources of noises is coming from your mains plug. A bad quality ground is a bad reference for a clean signal, by example but, there are other kind of noises that can travel along your electricity lines, as Radio-Frequency noises, electrical parasites, inductions from powerful engines, etc.
If you are thinking on buy a Power Supply unit to feed your pedals, you should considere a quality unit that can provide isolation of your mains line. This is usually achieved with a toroidal transformer.  In the first part of "Guitar Amp: How it works" set of articles, I've described the basics of a transformer. A tranformer isolates the line on the primary from the line or lines on its secondary. So, you have a way to reject some of the noises that are coming in your mains line.
A better power supply unit will have isolated outputs,  so whatever that's happening in one output (one pedal) isn't affecting the rest of outputs (pedals). This is specially a MUST when you are mixing PNP and NPN devices, with oposite electrical polarity. When you mix an old Germanium fuzz, that works with oposite polarity than your rest of pedals, you need to run this pedal electrically isolated from the rest.
A good way to achieve this is to use a power supply unit with a transformer and isolated outputs.
A good example of such an unit is the Pedal Power 2 Plus by Voodoo Labs.
To better fight against the remaining noise, your entire rig can benefite of the use of some Voltage Adaptor unit. Those units, usually include high quality filters to minimize the impact of RF and other electrical noises present in your electrical lines. Additonaly to this, they have safety circuits to protect your equipment from Peaks, Overloads and other anomalies that can ruin your rig. Finally, they maintain a regulated constant flow of filtered voltage level, to let your rig to work within an stable electricity flow.
Voltage Adaptors are expensive, specially those specialized for audio (as Furman high-end line).
If you cannot go for a Power Supply of the quality of the mentioned one from Voodoo Lab, be sure you run in separated power supply devices your negative and positive polarity pedals.
By example, you can use as single AC adaptor with several not isolated outputs to feed your pedals (way cheaper than a Power Supply unit) but, if you have some pedal with oposite polarity (classically, a germanium fuzz), run one more separated AC adaptor for that single pedal. This will reduce your noise.
Finally, I would like to mention that to use the powerful and durable battery isn't always the best.
Paradojically, most effects seem to work best with the old radio shack batteries, nothing alcaline or rechargable, or long duration, etc.
Specially, old effects and reissues of such an effects work better with that kind of old battery designs and, even better if the battery is mostly worn (discharged). This is very usual with old fuzz designs, by example.
The Voodoo Labs Pedal Power 2 Plus unit, has two of its outputs that can be switched on to emulate the use of worn batteries, as a curiosity.
Anyway, noise reduces your dynamic range, because the floor noise goes closer to your signal average level and, usually not good for our ears. Therefore, noise can be considered as a kind of Tone Sucker.
You can take a look to the articles I've already posted about cables. I will not repeat its content.
It's just curious how many times we are expending a lot of money in Guitars, pedals and amps (usually in that order) and we forget the importance of a good cable.
I am not talking about to expend a big amount of money but, just to get a quality cable, that can preserve your guitar' signal characteristics without noise or microphonics.
If the cable that links our guitar to the pedal board and, the pedal board to the amp is usually being forget, we go even worst with patch cables, buying the cheapest cable we can find on the store.
Once more, moster Noise visits us.
Just be sure to link all your gear with quality cables (not necesarely the most expensive, just of quality).
Jacks are everywhere on our rig, linking everthing together. Please, use quality jacks and, maintain the contacts always shinny and clean, for a better transference of your signal's quality. Use that kind of dirty-remover for metals products for that or some contact-cleaner spray that can be found in a bunch of places.

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