02 May 2013

Pedal Effects: Hardwired, True Bypass, Buffered, Impedances: pedalboard madness


Note: this entry was already published in my old Spanish version of this blog, around March/2011. I am just revisiting it here for its possible interest.

If your pedalboard loads just Boss or Maxon pedals, you wouldn't probably know about the issues we are going to talk right now. Boss and Maxon effects mostly have quality buffers.
Usually, if your pedalboard loads pedal effects of the same maker, it's very possible that all them are compatible, presenting no issues.
But, lot of boutique pedals that try to reproduce some vintage units can sound nice by themselves and be a real mess when trying to integrate them on your pedalboard.

In pedal effects world, you will often hear or read about Hardwired (HW), True Bypass (TB) or Buffered (BF), even Buffered Bypass (BB).

Let try to understand what is behind those concepts, pros and cons but, to make it short, when you mix those categories in same pedalboard you could have some tone issues.

I will present a practical example, with the fight I had with my current pedalboard (note: not my current pedalboard but, what I had in March/2011), trying to fit some vintage designed units.
We will see also the procedure to recognize our "tone-sucker" pedals and, how to insert them in the chain.

Interested?. Let go ahead...

Hardwired or True Bypass

Both words mean more or less the same and, both refer to a direct connexion from the input to the output jack, bypassing the effect's circuitry.

Well, that's true in part. Reality is that the input and output jack wires go to a pedal switch (DPDT on/on if no led or 3PDT on/on if led) and, that switch put both in contact or send both to the corresponding input and output spots in the pedal's circuitry.

The idea behind TB or HW is to completely bypass the pedal when it is being switched off so, your guitar's cable physically is being prolonged up to the next pedal in the chain (if any).

The pros of TB are that your guitar will never shut up if your pedal's battery dies or if your AC transformer provides no current (broken wire or whatever) and, that since your cable "bypasses" the pedal circuitry, your tone is being "preserved." No electronics component can affect your tone (well, we will discuss about this a bit below).
If the pedal is being switched ON, our tone will be affected by pedal's circuitry. Evidently.

The potential drawback of TB is that, since it's virtually prolonging our guitar's cable, its capacitancy (that increases with length) will be increased and, depending on the length (about 30 feet, 10 meter, it's clearly notable but, can happen even before) of that "virtual cable", the higher content of your guitar's tone will be rolled off. Your sound will loose sparkle, punch, bite and definition, turning to dark, dimmed and lifeless.
So, when you have all your pedals TB, the virtual length of your cable includes: the guitar to pedalboard cable, patch cables between your pedals, wires from jacks to pedal switches and your pedalboard to amp cable (or cables).
By example, if you had 20 cm patch cables, the inner wires jack-to-switch were about 10 cm and, you had a couple of 4.5 meter cables (guitar, amp) and 5 TB pedals, you will have a virtual length of: 4.5 + 4.5 + (4 * 2 * (0.20+0.10)) = 11,4 m
Even that TB is being designed to preserve your guitar's tone, my own experience says that not all TB pedals in bypass mode work the same. I made a comparison with three Buffer/Line Drive pedals, one at once (and the only pedal between guitar and amp) and, I was surprised seen that except for the Wampler's one, the rest were slightly sucking the tone (one clearly more than the other) in bypass mode!.

I've opened the Wampler's unit and the other two to understand what could make the difference. Despite of the makers of each jack and switch, Wampler's pedal had it's pedal switch inserted in a PCB circuit, while the others had jack wires directly soldered to the switch (shouldn't it be "purest path"?).
I dunno what makes the difference, quality of jacks and switch? that PCB? wires?.
I have no clue but, this is a repeatable experiment that gives every time same results and... yes... it's weird, indeed!.


A buffer is an unitary amplifying circuit which the goal of re-strenghtening your signal while preserving the original tone and, adjusting the input and output impedances to the needs of pedal's circuitry.

Buffered pedals run both, the input and output jacks thru the circuitry. When the pedal is off, the signal goes just thru buffers (some pedals have input buffer, some have output buffer, some have both).

The pros of a buffered pedal is that it shortens that "virtual guitar cable" and restores full signal strength and frequential content.
Main drawback is that a buffered pedal, since some electronics components form part of the buffer, will die if it receives no current (died battery, wrong AC plug), even if it's being switched off. So your guitar will completely shut up if you don't remove such a pedal from the path or if you don't restore current there (new battery, by example).
That seems a good approach, right?.

Well, if you remember my past entry The Cost of the Cup of Tone, we've already seen that as soon as you introduce some amplifying component in a signal path, your original signal deads and, new signal is being generated in such an amplifier. Therefore, the quality of a buffer design is essential to preserve your guitar's tone. A bad buffer can work as a real tone-sucker and be a worst election than to have it in True Bypass mode.

There are dedicated Buffer pedal effects, designed with high quality buffers that can restore the signal strength and tone to be delivered to the rest of pedals in the chain. But, even between Buffer pedals there are clear differences.

By example, I've found MXR CAE MC401 or even Wampler's Clean Buffer to make the sound thinner and treblier, making the sound to loose some body.
Mad Professor's Ruby Red Booster is a very good one (and the versatiler you can find) but, Wampler's Decibel+ is the one providing the most useful tone, in my honest opinion.

Visual Sound's pedals have quality buffers and, they call them "True Tone Bypass" but, don't be fooled. They are buffered pedals, all the way.

Buffered Bypass

This is just how a lot of pedals work. Even if they are True Bypass when swtiched off, as soon as you switch them on, signal goes thru buffers before or after the circuitry. This helps to the own effect unit to have a good signal and impedance levels to do its job in the best way.
Once again, depending on the quality of buffers and rest of components, the results of the effect unit will differ in sound quality.


This beautiful and bombastic name is the responsible for most of the issues we can find in a pedalboard (among many other audio environments)
Impedance is a concept for Alternating Current similar to resistance for Direct Current. It's being mathematically expressed by means of a Complex number, where its Real part is the resistance while its Imaginary part is the Reactance.

Wait... what the heck are you talking about?

While in DC world, things are very easy to measure, because current goes in a single direction, in AC world, current fluctuates in both directions and changes in phase and polarity cyclely. So, in order to use same concepts in AC like in DC, we need to measure "average values" that will behave in a similar way as the same component with such a value in a DC circuit.

While inside pedals current is DC, our pickups generate AC current that must be adapted to the DC current inside the pedal and, readapted at the pedal's output to be converted to AC again (for next pedal or amp's input).

The impedance is an AC "average value" that corresponds to the resistance concept for DC, but isn't exactly the same.
Ideally, every pedal should have an infinite input impedance and a zero output impedance but, this is impossible in real world. The use of buffer stages in pedals allow to interface between the guitar impedance levels and the impedance levels that need the components of the pedal effect.

Quality buffers often achieve an input impedance of about 1 MOhm (or higher) and output impedances around 600 Ohm (or lower).

Most of the early designed pedal effects weren't designed with buffers and, wasn't really concerned about interaction with other pedal effects. During that early times, there were very few pedal effects available and, usually, you wouldn't see more than one or two effects in a rig. The clean sound was more important than any processed sound. Effects were more common in Recording Studios, were a technician or engineer was adjusting everything together for a good recording.

The input and output impedance levels of the several pedals (even of the same maker) are the main source of issues to arrange your pedal chain.

Modern, Vintage and Boutique pedals

Have buffer every modern pedal effect?
Are all  vintage pedals tone-suckers?
Are boutique pedals free of issues?

You should already realized that makers, once they have some successful pedal effect in the market, they start to produce new versions or evolutions of such a pedal, from time to time.
Those new versions can occurs because two main causes:
  • Maybe, some key component cannot be sourced anymore (usually, some chip or transistor). This obliges to the maker to produce a new version, with a substitute component and, to re-adjust everything trying to get as close as possible to the sound of the original version.
  • Maybe, its pedal is awesome when played alone but, as soon as it's being stacked together with other successful effects in the trend, they suck and then, people starts to remove it from his pedalboard, what affects to their sales. In that case, a re-design can be necessary to make that pedal more pedalboard-friendly.
In both cases, the original sound will be altered but, sometimes, the lost justifies the benefices of such a re-design.

Usually, the main tone-sucker pedals are the very early pioneers of Vintage pedals. Those pedals often weren't True-Bypass. Some even hadn't buffered output/input and, some were even designed for Keyboards instead of Guitars (impedance levels on those instruments is way different!).

Vintage Wahs and Fuzzes hardly compete for the Price to the Most Tone-Sucker Pedal.
Those pedals often sound good just when they see the guitar directly connected and, they often work ugly when some other pedal is between that pedal and the guitar.
Those kind of pedals are always competing for being the first in your pedalboard chain.

Rest of vintage tone-sucker effects can better support other positions in the pedalboard.

Some vintage effects already had buffers but, not all them had quality buffers. Boss and Maxon pedals were designed mostly with quality buffers, by example.

In the Boutique world, we have a bit of everything together.
In one side, most of Boutiquers try to bring back to life a vintage unit, being absolutely faithful to the original design and components. That achieves the sound, indeed but, carries on the original drawbacks, also.

Some others, include small variations, as to add a Led light to know when the effect is on or off and, even a True Bypass switching system. They can even add some buffers to get rid of impedance issues, when the effect is on. This clearly affects the tone but, they go so close as possible, while making the pedal more friendly.

In general, well established pedal makers, with a long tradition in the effects world, were constantly enhancing their designs to solve the issues with vintage units, as soon as they started to be stacked with modern designed units (of the same or other maker).
This brings a more consistent pedalboard but... elves exist in musical gear. Many of such an "enhancements" ruined the original tone and, therefore, there is a lot of people searching the original units, because is there were the tone was.
Those makers, seen how the boutique market spreads, started to reissue their own "custom shop" or "reissue" versions of their own mythical units, at an expensive price (but always below the boutique price).

So, we have again the dog eating its tail. We bring back the "tone" and all the issues to insert that da-bomb pedal in our pedalboard.

Don't loose your head!

Most of pedalboard headaches are coming for the fight for the very first place in the chain of pedals. If that goes wrong, the issue is being propagated to the rest of the chain.
As soon as we have a vintage fuzz or wah (goes worst if we have both), they should go first in the chain.
When we have both, best solution is to have a fuzz-friendly Wah (like Real McCoy wahs), that is, a wah that includes some buffer to fool the fuzz that follows the wah.

Probably the worst pedal to deal with is a fuzz and, very concretely those fuzzes based in vintage germanium transistors. Those pedals are a real headache in every sense. They work with reversed polarity (what forces you to use separate AC transformers or isolated outputs), they are very sensitive to temperature changes and, they are very sensitive to the input impedance level, what can drastically change their voice and, go from organic to synthetic. Also, those fuzzes love worn batteries (and old ones, no modern high performance ones)
Usually, some looper pedal removes this kind of pedals out of the chain, as soon as they are switched off.
Other pedals that can compete in the pedalboard head are a vintage compressor and a tuner, by example.
This is the process I've followed myself trying to determine the pedalboard head:

I had the following candidates:
  • Tuner: Korg Pitchblade
  • Wah: Real McCoy RCM4 Picture Wah
  • Compressor: MXR '76 Vintage Dyna Comp re-issue
  • Fuzz: Hudson Electronics Stroll On (clone of Tone Bender MKII)
Step 1: to test guitar with each single pedal alone

First, I've directly plugged the guitar in the amp and, adjusted controls to taste.
Then I've tested each pedal, separately to check how they sounded alone and how they affected my tone when switched on and off.

Every pedal, while off, leaved the original signal unaffected, except for the Dyna Comp. It seems that the circuitry of the Dyna Comp produces a drop in level and some lost of lows or increase of highs, while off.
An small touch in the amp's gain got rid off of such an issue.
So, first tone-sucker was identified: the Dyna Comp.

Step 2: Adding pedals step by step and, swap positions

Because of previous tests, I was clear that this fuzz stacked immediately after that wah wasn't an issue. The Real McCoy is fuzz-friendly. Fortunately, this part of the job was already done.
My main doubt was were to place that Dyna Comp, to be in the less harmful place.
I've tested it first after and before the tuner, taking notes.

Compressor -> Tuner = weaker signal, enhanced high end.
Tuner -> Compressor = same results

Therefore, the order between those pedals affects not to results so, I leaved apart the tuner and, checked the position before and after wah-fuzz.

Compressor -> Wah = weaker signal, enhanced high end
Wah -> Compressor = same results

So, it's the same where to place it. It will suck the tone anywhere.

After trying several combinations, I've found the less harmful the following order:
Wah -> Compressor -> Tuner
I've called this chain of pedals Block A.
An small increase in amp's gain was enough to make the guitar to sound better.

Then, I wanted to test the Vibe effect. I usually like vibes before gain pedals. Specially after the fuzz, it sound really ugly.
The Roger Mayer's Voodoo Vibe+ has one of the smarter designs that you will find. It's not offering just a switching system but both, at your will. It has one Hardwired and two Buffered outputs so, you can easily choose the type of output that better works in your chain.
I've tested both outputs with the pedal alone and, the buffered one sounded way better so, I've used such an output and stacked it after Block A.

Block A -> vibe = Block B.

Then, it was time to insert the Phaser. Usually, I like Phaser after Vibe but before any gain pedal.
Phaser was a MXR '74 Phase 90 reissue.
Tried both output types in the vibe and, even that both worked well, the sound was better with the buffered output so, I leaved it.

Block B -> Phaser = Block C

Time to see where to insert the fuzz and, this is where the fun starts.

While off, the fuzz presented no issues, respect to how the Block C was arranged but, as soon as the effect was switched on, what I've achieved is some kind of weird electronics feedback.
Even that the Phase 90 sounded best with the buffered output of the Vibe, I suspected that this was the issue for the fuzz and, therefore, I've used the hardwired output, instead.
Clearly, that fuzz doesn't like a signal coming from a quality buffer. Fortunately, the versatility of the Vibe pedal allowed me to get rid of this issue, this time.

Once, those potentially problematic pedals were arranged, rest of pedalboard is often way easier.
Overdrives and distortions are the following candidates in the chain and, even old designs as the RAT often work without issues.
I've arranged gain pedals from the dirtier to the cleaner:

RAT 2 -> MXR Distortion III -> OCD -> EP Booster

Between Vibe and Phase 90, I've inserted an EH Small Stone Nano, because I have pending a comparison between both Phase effects.
The original Small Stone is a true tone-sucker. It drops a lot the signal level and sharps the highs. This issue wasn't present in the Nano version of such a pedal and, it's even smaller.
Between the Nano and Phase 90 there is some incompatibility, both work better if the Nano is being stacked before the 90.

Another couple of pedals that have issues when stacked together are the Ibanez TS-808 reissue and the Fulltone OCD V3. You have to check one before the other to minimize the issue.

The pedalboard was arranged as follows:

  1. Wah: Real McCoy RMC4 Picture Wah
  2. Compressor: MXR '76 Vintage Dyna Comp re-issue
  3. Tuner: Korg Pitchblade
  4. Vibe: Roger Mayer Voodoo Vibe+
  5. Phaser: Electro-Harmonix Small Stone Nano
  6. Phaser: MXR '74 Vintage Phase 90 re-issue 
  7. Fuzz: Hudson Electronics Stroll On
  8. Distortion: ProCo RAT 2
  9. Distortion: MXR Distortion III
  10. Overdrive: Fulltone OCD V3
  11. Booster: Xotic EP Booster

To get the right order in your pedalboard is a matter of patience and, something you should do every time a new pedal cames.

You can foreseen issues when vintage fuzz and wah are in your pedalboard but, also with certain vintage mythical units, as the Dyna Comp or the Small Stone but, also with boutique pedals as the Fulltone OCD.

It's a good practice to read pedal technical specifications to know their input and output impedance levels.
When two pedals are in conflict, your sound will be better (or less damaged) if you stack first the one with higher input levels. Take into consideration that some pedals deliver a very high output level and, this can be a mess if its output level is higher or close to the input level of the following pedal in the chain.

Sometimes, a nice pedal that sounds awesome alone can be the worst we can use, because it ruins the rest of the chain. Use a looper to insert it only when strictly necessary or, remove it from your chain.

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