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The Truth...

- a big and bold title, I know - but it is...

Ever so often, someone claims that such-and-such pedal is true bypass, either having been told so by a salesperson, or having convinced themselves it is, or simply because the manufacturer says so. Quite often, these claims turn out to be untrue. In some cases, it is evident that the manufacturer has tried to use terms that come as close as possible, without actually claiming outright that the product is true bypass. In other cases, they simply don't seem to care. I decided to make a list of questionable cases I've come across, simply because I can. So here goes:

Boss has never before earned a place here, but now it is time. The stupendously large and expensive TU-1000 stage tuner has a "parallel" output jack (sitting in parallel to the input jack) which in the official Boss marketing video is said to output a "true bypass signal". Unless Boss has gone out of their way to make the electronic switching system also physically disconnect the tuner input from this jack when the pedal is inactive (which would be highly unlikely), it can simply not be true. Using this jack will place the same impedance load on the guitar signal as connecting the tuner to the "tuner out" jack on a volume pedal.

When Maxon released their "nine" series pedals - reissues of the classic Ibanez 9 series pedals from the early '80s - they claimed that they featured true bypass switching. They do now - all pedals produced after the early 2004 release of the second series pedals (AD-9, CS-9pro and FL-9) are indeed true bypass. But the ones made before that point in time wasn't. Read all about it here, where you also will find out what to look for if you're shopping for a Maxon AF-9, OD-9 or SD-9.

Meanwhile, it's the same story with the Vintage series (the large box pedals reminiscent of mid-to-late 70s Ibanez pedals) - Maxon advertises them as being true bypass, but no... most of them will also only switch the output signal, just like the pre 2004 "nine" series, MXR, Marshall et al. So while the "nine" series changed to actual true bypass wiring, Maxon is still mostly bulls***ting us about the "vintage" series. The only exceptions are the pedals that have a "4PDT" symbol (the new AD999 for instance) - those may well be wired for true bypass, the same way as the new "nine" series (also with 4PDT switches) are.

Ibanez states in the manual that their WD-7 "Weeping Demon" wah pedal is true bypass. This made me quite suspiscious, mainly because that would mean a big and expensive step away from the tried and proven electronic bypass system they've used for over 25 years now. Also, the pedal has an auto on/off function, which can't be combined with a true bypass system without the use of logic controlled relays to switch the audio. That would be even more expensive... Naturally, I had to check this out, so I headed for the music shop. Sure enough, they had a WD-7 on display. I didn't get to take it apart because it was mounted in a display rack, but I had a hunch I'd be able to figure this one out from the outside.

The pedal in question didn't display any of the tell-tale signs of relay switching (there were no clicks or anything coming from the inside of the pedal), so I went ahead and did the "power test" (taking the battery and power supply out, to see if it still passes signal). As we all know, you can't tell from that test if the pedal has a proper true bypass or the half-assed mechanical bypass found on Dunlop/MXR, DODs with stompswitches etc, since both bypass types will pass signal when the pedal is powerless. But if the pedal has an electronic flip-flop bypass system (as found on Boss/Ibanez etc), taking the battery out will most definitely make a difference - that type of system can't pass any signal at all without power.

And... without power, the WD-7 was completely dead - just as dead as any electronically switched and buffered Boss-type pedal would be without juice. So the WD-7 definitely does not have true bypass or any sort of physical link from input to output. Of course, that doesn't make it a bad wah pedal per se - if anything, when placed first in the chain, the fully buffered electronic bypass system it has is probably preferable to the mechanical crappy bypass system in a Dunlop GCB-95 Crybaby... But what it does mean is that Ibanez is misusing the term "true bypass".

Also, the LU20 pedal tuner is advertised as having true bypass. Now, I haven't seen this one in person yet (and probably won't, as my local dealer didn't think it looked solid enough to bother carrying) but I did take a quick peek in the manual. The only time the footswitch is mentioned is as a means to mute the signal, should you want to. IF the LU20 is true bypass, the tuner won't work at all unless you step on the switch - and if so, the first line in the operating instructions would read something to the effect of "to activate the tuner, step on the footswitch"... So, until I've been proven wrong, I'm going to declare this one most probably not true bypass.

MXR (Dunlop) is another example where there are plenty of myths and misconceptions around. Some were propagated by Dunlop themselves, while others thrive in various internet forums etc. The term "hardwire bypass" can be a little misleading, but in short it is the same thing that causes old Vox wah pedals to suck tone. The signal is simply split at the input, leaving the circuit constantly connected ("hardwired"), which places the circuit's input impedance in parallel to the input impedance of the next pedal, bringing the total down. Plug your guitar into one of these pedals, and the output into a 470K input impedance Boss pedal, and the total input impedance the guitar pickups "sees" will be below 470K. How low depends on the Dunlop pedal, but rest assured that this is no true bypass.

Lately, Dunlop has started using the term "true hardwire bypass" to denote pedals that are actually true bypass (not just "hardwire"), which is good. Some of the newer designs (Carbon Copy etc) are proper true bypass (using a variant on the Millennium circuit to control the LED), while the older ones tend to stay "hardwire" until they are due for a redesign for other reasons.

Marshall have not officially used the term "true bypass" in the advertising for their line of pedals. However, some dealers have taken it on themselves to add the word "true" to the official Marshall term "passive bypass". Inspections of both the pedals and the schematics prove that these pedals have the same bypass system as MXR/Dunlop and the others - the effect input is hardwired to the main input, and the switch only selects which signal to send to the output. The only difference is that some of them (mainly the distortion/overdrive pedals) have an extra feature that mutes the input to the distortion circuit, to avoid crosstalk in the switch (a common complaint with the output switching only system). Some confusion arose when people started finding 3PDT switches (normally associated with true bypass switching) in some of the newer pedals, but it turned out to be a red herring, as the pedals in question had stereo outputs. To do the "output only" style of switching on a pedal with stereo outputs, you need an extra set of poles - hence the 3PDT instead of a DPDT (as the mono output Marshall pedals have).

Hughes & Kettner has a reference in their adverts to something they call "hardware bypass" - which, of course, is the same thing as the "hardwire bypass" preferred by Dunlop/MXR. H&K even references the MXR system, to boast how good theirs is... No dice.

Zoom has a rather popular line of analog pedals - PD-01 Power Drive; TM-01 Tri Metal; HL-01 Hyper Lead; UF-01 Ultra Fuzz (link) - that among other things has been hailed for having true bypass. It was like a dream come true - great pedals (the PD-01 is sometimes called the poor man's Klon, and justifiably so), but as so many times before, if it seems too good to be true, it most likely is... I've seen a schematic (reverse engineered, though, not factory original) of the Tri Metal that most definitely wasn't true bypass, and the old power test also comes up positive for non-TB. These pedals will not pass any signal at all when the power is removed, which is a tell-tale sign of something electronic/active sitting in the bypass signal's path. Ergo: they are not true bypass, despite Zoom advertising them as such. Here's what the spec sheet for the PD-01 and TM-01 says:

"Mechanical/True BYPASS circuit passes a totally un-effected guitar signal."

Interestingly enough, the spec sheet for the other two pedals (the HL-01 and UF-01) has a slightly different version:

"True Mechanical BYPASS circuit passes the unprocessed guitar signal through intact."

Nevertheless, these pedals are most definitely not TB, no matter what the manual says... they are surprisingly good (especially the Power Drive), but that doesn't make them any more true bypass.

Radial makes a selling point with the claim that their Tonebone tube overdrive pedals have true bypass. Here's a snippet from the Classic/Hot British manual:

FOOTSWITCH: Toggles between effect and True-Bypass. i.e. when the Tonebone is off, the signal passes straight through without any effect.

If only... I recently got my hands on a schematic for the Classic, and it shows the input being hardwired to the circuit input as well as the switch, just like in most wah pedals and the MXR, Marshall etc pedals mentioned above. Half of the DPDT footswitch is used for the audio (selecting either the circuit output or the signal tapped off straight from the input jack), with the other half switching the LED on/off. So as far as that schematic is concerned, no - the Tonebone Classic is definitely not true bypass. The signal passes straight through to the output jack, yes, but it also taps off to the circuit input, which can lead to tone loss. And again - it isn't true bypass.

Someone (not me) e-mailed Radial about it, and their tech department had this to say:

"The Tonebone is true bypass. True bypass means that when the switch is in bypass mode the signal travels directly from the input to the output without going through any circuitry. This is what the Tonebone Bypass switch does."

Um, no. There are some nice semantics there... the author of that e-mail very nicely describes what their bypass system does, but avoids the real question by using the words "going through". That description will work for a stock Crybaby too, so it's not any conclusive proof regarding the Tonebone pedals. In the FAQ section for the Tonebone Classic, they describe the "true bypass" wiring in the pedal like this:

Q: Is Tonebone 'true bypass'?
A: Yes. When the pedal is off, the sound passes straight through it without connecting to any electronic circuitry, even if the power adapter is not plugged in.

The reference to the age-old "power test" - which we all know is not a valid test for true bypass - is a bit confusing. But if the words "without connecting to" are to be taken as gospel, Radial might have changed the design. A stock Crybaby can be said to have a bypass system where the signal doesn't go through any circuitry, but it most definitely connects to the circuit. So it is possible that there has been a change here - but I'd definitely want to verify this myself, before removing Radial from this page. In another post on the same FAQ page, they have a fairly correct description of what "true bypass" means:

Q: What is 'true bypass'?
A: The term 'true bypass' came about because of the problems associated with some pedals that even when off, were affecting the tone by loading down the guitar's pickup. This means that instead of 100% of the signal bypassing the effect pedal circuitry, some of some of the signal is 'sucked' into the pedal even when it is not being used. The perfect ‘true bypass’ switch completely disconnects the pedals circuit board from the signal path. Unfortunately, this type of pure mechanical switch causes pops in the audio path when switched in and out.

Note that they don't quite connect the two statements. The last sentence here (about the possible switch "pops") almost feels like it's missing a "therefore we don't..." bit. Oh well. What I'd really love to do - aside from taking apart a Tonebone (from the latest batch) myself - is to have a chat with Radial's tech department, where I can ask a few specific questions. That might put this puppy to rest. So Radial - feel free to e-mail me

Digitech has a nice brochure ready for download about their Whammy pedal (the Whammy 4, to be precise). And lo and behold, here's what they say:

"Rugged mechanical footswitch takes the Whammy pedal in and out of a true signal bypass"

Um... I can tell you with the utmost certainty that this pedal is definitely not true bypass. It is interesting to note their choice of words - so far, every time a manufacturer has stuck additional buzzwords in between the words "true" and "bypass" ("true hard bypass", "true hardwire bypass", or indeed "true signal bypass" as used above), the pedal in question has turned out to not be TB. Every time... It's almost like they know their pedals don't fit the bill, so they invent a slightly different term to avoid being called out as liars. Of course, bending the truth is still bending the truth, even if it's done by implying things rather than stating them outright. But it is an interesting observation nonetheless.

Planet Waves has a pedal tuner out, to which they've attached the term "true hard bypass". I have taken one apart, and it turned out to be sort of true bypass - the switch does disconnect the tuner circuit from the main signal path, but there's still a 680 or so Kohm path from hot to ground present in the bypass line. That doesn't qualify as proper true bypass. Sorry.

If you want a more detailed description of why the Planet Waves tuner doesn't qualify for being called true bypass (in my opinion), go here.

Peterson Strobostomp was long hailed as the first (and only) pedal tuner with true bypass. And all the stuff needed for true bypass is there - with the small switches set the right way (it ships in buffered mode) the footswitch does everything right. But... for some reason, Peterson has stuck a 1 megohm resistor from hot to ground in the bypass path, which of course ends up in parallel to the input impedance of the next pedal. As tuners tend to sit first in line, the lowered input impedance "seen" by the guitar can lead to treble loss.

Peterson claims that resistor is needed to stop the pedal making popping noises when switching - a good old pull-down resistor, thus, just like the Dunlop 535Q wah mentioned earlier. Once again, pulldown resistors should be located on the circuit input (as they're intended to pull the circuit input to ground during the switching operation), and therefore out of the bypass signal path. Placing them where Peterson did won't help pulling the circuit input to ground - all it does now is present a constant 1M input impedance in bypass mode. Still, it is entirely possible that Peterson had to do this to stop the popping (and it is also equally possible that removing this resistor, while stopping the treble loss, also makes the pedal "pop" when switched), but then they shouldn't have called it "true bypass".

Vox claim that their Cooltron series of pedals are true bypass. I decided to investigate, and borrowed one (a Big Ben Overdrive) from my local dealer. I started out by hooking the pedal up without any power source, and the pedal did pass signal just fine. While this is not a test that can help you determine if the pedal is actually true bypass, it will show if there are any active circuits in the direct signal path when bypassed.

I then took the pedal apart and was able to trace the signal from the input jack, through the switch to the output jack. That's how far you'll get with the "battery test" as well, so it was merely a confirmation of what I already knew. But... the switch didn't seem to have any other place to route the input jack's signal to, other than the output jack, which is a prerequisite for true bypass (the switch needs to route the input signal either to the circuit or straight to output). Only one half of the DPDT switch seemed to handle the audio signal, which meant that this was starting to look the same as all the others (MXR, Marshall et al). Now, the Cooltron pedals use tiny surface-mount components, so tracing the thing was not easy. But finally, I was able to determine that the signal from the input jack is split off in two paths - one leading to the switch (and from there to the output jack) and the other through R53, C11 and further into the circuit.

So, in conclusion, no. The Vox Cooltron pedals are not true bypass. They have the same bypass scheme as Dunlop/MXR, Marshall, Radial and the others mentioned earlier in this article. If Dunlop had built it, they'd have called it "hardwire bypass", because that's what it is.

Behringer use a variety of terms to describe the bypass system in their line of stompboxes, all designed to confuse the customer (if you ask me). Here are a couple of them:

As you can see, the descriptions range from fully electronic (Boss-style) switching to something that is intended to remind people of true bypass. And as it seems, the newer and more advanced the pedal (the higher the number), the closer to saying "true bypass" the descriptions seems to get. Now, I have of course not inspected all of the Boss look-alikes (mind you, some of them seem only to exist as vector drawings on the Behringer website), but the ones I have seen have all had a fully buffered electronic bypass system. Nothing wrong with that, so why confuse the issue?

Some of the Behringers use a mechanical stomp switch, and are described as having "true hardwire bypass", which seems reasonable. Not true bypass, of course, but they didn't say that either, did they? By the way, according to one owner of the PH9 (MXR-style phaser also advertised with "true hardwire bypass"), the switch is actually just an actuator pushing down on a micro switch on the circuit board - to me, that sounds like electronic bypass. Again, nothing wrong with that. But why call it something else?

...and one exception to the rule?

I have said it many times - every time a manufacturer has stuck something in between the words "true" and "bypass" ("true hard bypass", "true hardwire bypass", etc), the pedal has turned out to not be true bypass. So far, this has been the case - every time, without exception. But now there may be one exception after all. Digitech's new line of "Hardwire" pedals apparently use relay switching, and according to a Digitech representative the system disconnects the circuit at both the input and output. I haven't verified this for myself, but if that's true it is the first time the term "Hardwire bypass" actually means true bypass...

 

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