Colorless writings, part 5 – The Bypass Surgery

Bypass surgery? Are you referring to bypass systems found in pedals?

You got that right. True-bypass seems to many as a something that will make them play better. I thought i’d like open up and let you know what i think about different bypass and switching methods. From outside, sort of generalizing, there are just couple of ways to create bypass switching on a effect pedal. We all do want to have bypass option on our pedals, right? At least i do. The unusable options are mechanical switches that have input of the circuit connected all the time. This method always results is this mythical “tone sucking” that so many of you are talking about around the internet. I haven’t come accross any modern pedal, boutique or factory made, that would use this method as main bypass switching, so we can safely leave that be. The usual two ways are magical “true bypass” that will set you free and save the world from certain death and the “buffered bypass” that is demon’s work and will *always* suck your signal dry before it hits the amplifier’s high impedance input. Or that’s exactly how i’ve seem people act on this issue.

Let’s start with the myths about true bypass. It will not make you play better, nor will it save the world. It’s just a method that will let your signal travel through the pedal without touching any part of the circuit. Yes, there are things that are good with this method. First of all, it doesn’t change the impedance of your signal when effect is not engaged. This means that your signal will travel happily in tact from your guitar to your amplifier. In addition, i can quickly think of two things that are not so good.

  1. Switches may be and are unreliable
  2. The lack of buffering will have your signal travel through 6 metres of guitar cable -> pedalboard with about 20 connections -> another 6 metres of guitar cable

No matter what you say. The standard 3PDT stomp switch used in almost every single boutique pedal will at least once or twice in its life span leave one or more of the poles unconnected. This usually fixes itself on the next stomp, but it is still very annoying.  It’s not the matter of build quality of these switches, but a simple fault in a way switches work. Many modern factory pedals are also using 3PDTs or 4PDTs as stomp switches – because it is hip to have this mythical thing called “True-Bypass”. Old school 2PDTs are known to be more reliable, but they limit switching options and usually leave the LED indicator out. Or address the issue in some other manner.

The example above leaves you with approx. 15 metres of guitar cable between your guitar and your amplifier. There are many jack/plug connections on the way too. Do you really think your signal generated by the guitar is strong enough to travel that many connections and that much cable without being degraded? Didn’t think so. This is what makes true bypass bad. You’ll have to rely on your cable quality and the connections on pedals.

So you’re saying that true bypass is a bad thing?!?

Oh yes i am. The impedance is the key. Guitar output impedance (or Z, or AC resistance) is always low in Ohms. Usually around a few thousand Ohms, less than 10K. The next item that takes the signal in will need to have a high impedance to catch the signal and pass it on. Usual amplifiers and pedals have input impedance from around 500K (which is lowish) to 1M Ohms (which is good) and up. Longer the cable, higher the output impedance for your guitar’s signal. Two six meter cables and and a pedalboard seems like quite standard setup for many. In this setup your signal can be degraded before hitting the amp due to long cables and lots of connections in the way.

Now let’s think about putting a simple buffer in there, middle of the pedal board. Buffers are just very simple semiconductor devices that transform the impedance back to low value and still keeping the signal in tact. If we have one of those in the middle of the chain, we’ve basically cut the cable lenght in half. The guitar “sees” the high impedance input of a buffer after first six meters of cable. The amp “sees” the low output impedance coming from the buffer’s output and percieves that as only 6 metres of cable. Good buffers can push you through even considerably longer cables without a problem.

So you’re saying buffered bypass is a good thing?

Yes and no. Like most things in life, it is just not that simple. Well designed bufferes are always more than welcome to my pedal board. Bad designs with even worse electronics switching.. Not that much.

The other reason for buffered bypass (or buffered pedals in general) is the electronic switching. As the JFET switching will need at least reference voltage of ~4.5V to work, the designers can’t just take the input to JFET switching “buffer” – that would take the voltage to the pickups, and that’s not what we ordered. So there needs to be a buffer to separate (or decouple) the input, JFET electronic switching and the next phase, which is either output buffer or the effects circuit. On the other view, some otherwise perfectly working circuits will need an input buffering to get the incoming signal just right. If there isn’t input buffering, the too low input impedance will cause something called “pickup loading”. In essence, it means that the guitar pickups are giving out too hign output impedance and the signal doesn’t get picked up by the circuit input well enough. Result will sound bad. Effects with too low input impedance do exist. And in numbers.

This brings us to the real issue and real practice. I don’t think that having true bypass in every single pedal in my board is good practice. Í also don’t think it’s a good idea to have in/out & bypass buffers in every pedal. Some sort of middle ground should be sufficient.

Does one exist?

Yeah. I think so. If you put your mind to it and think about how you want to build your pedal board.. You’ll get the hang of it.

Oh. There’s one more thing that popped in to my mind. Some people will probably remember when everyone wanted to modify their cheap pedals for true bypass? I have one question regarding that.. Did it make any of those pedals better than they were? I suppose there could be a case here and there where the TB’ing a pedal will help with the mythical tone sucking, but in general? Does it really help you to sound better?

I’ve had couple of pedals where i’ve heard the highs die when the effect was disengaged. I do think there is some psychoaural symptoms going on with that one too. What if the effect slightly boosts your highs? Then the buffered/bypasses signal would sound dull when disengaged. Have you used a/b testing to see if you can hear a difference between true bypassed signal and a buffered bypass?

In my opinion, the greatest solution to this age old, highly puzzling and opinion raising subject is the one we can today find in BJF Designed Mad Professor brand pedal, the Ruby Red Booster. This pedal has true bypass and buffered bypass switchable inside the enclosure. Ingenious. There should be more pedals with this option. Would be a big help for those who are designing or redesigning their pedal boards.

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