True Bypass switching: myths, pro's, cons, alternatives...

All frequent questions on switching: true or not true bypass, transistor-based or mechanical.

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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby BJF » 18 Oct 2008, 01:57

Hi,

Well, as my distributor told me there are people who won't buy a pedal if it's buffered, but there are no people that ever complained about a pedal being truebypass.

Loading occours ofcourse since a guitar pick up is high impedance and any capacitance in the cables will affect, of course if the cables are short and of antenna style like George L there won't be much loss.......yet sometimes losses are wanted like in Jimi Hendrix' system.

On emitter/ source followers as used in many pedals with 'silent footswitch' systems, these inevitably have a voltage gain less than 1,typically something like 96% to 98%. This is evident from the equation of an emitterfollower. On the input impedance of an emitterfollower for AC signals it would be expressed as the total emitterload-that's both the DC emitterload in parallell with the load the emitterfollower is driving,and if this would be called Re AC, Then
ReAC X hfe+hie gives the AC inputimpedans that in turn would be paralled by the bias network that by all means could be bootstrapped but likely not in a japanes pedal.......
OK so a standard BOSS pedal would have about 380K IZ.
This would effect a standard guitarpickup in lowering the resonant peak a bit as compared to a load of 1M ohms that could be supplied by a J-FET source follower, but still the amplification factor being less than 1 and the considering there would be two at least in series and that's only with one pedal there will be a voltage loss.
OP amps on the other hand can as buffers have an amplificationfactor of 1,000 and voltagetransfer would the be just that i.e the same voltage put in as is put out.

Further read on topic on buffers
http://bjfe.org/viewtopic.php?f=3&t=868

And yes most often I'd find at least on buffer needed to keep loading at desired level and indeed I keep one in my personal system.

Have fun
BJ

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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby analogguru » 18 Oct 2008, 08:13

For all these reasons Analogguru´s Pickup Probe was developed more than 25 years ago:
http://www.freestompboxes.org/viewtopic.php?f=13&t=3239

Ok, maybe a Fuzz Face doesn´t like it.... but in 1983 nobody liked a Fuzz Face.

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Re:

Postby DavidRavenMoon » 27 Dec 2008, 20:14

R.G. wrote:There is an outfit called Creation Audio Labs that sells a box called The Redeemer. It's a very high class buffer. If you run your guitar into it and then into the rest of the signal chain, you'd be amazed at the added clarity of the bypassed sound. Other simple buffers get you most of the way there.


I had been curious about this thing, mostly because the maker was saying things that made it sound like a buffer, and then said it wasn't a buffer. The one claim that really bugged me was saying you got more sustain because it unloaded the pickups (true) and that caused them to interfere with the strings less (false).

I had someone from the TalkBass forum loan me one so I could check it out. It was a nice sounding buffer. I decided to do a semi blind A/B test comparing it to a simple JFET buffer derived from a Stratoblaster, and also compared it to an EMG BTC preamp with the tone controls set flat.

I posted audio samples simply marked A, B, and C. Most of the forum members guessed the JFET was the Redeemer and most preferred the way it sounded. I think the Redeemer sounded better on guitar than bass. I liked the low end better with the JFET circuit, maybe because it didn't have an input coupling cap.

Buffers do this by making the sum of cable and wiring capacitance not matter. The guitar sees only the buffer input loading, which can be very, very small.


I'm a firm believer in buffers. Most of my basses have a buffer built in. I know I can plug into anything and get a good signal with no loading.

My take on the whole true bypass thing is that if you look at older effects pedals, they often used SPDT foot switches, probably because they were cheaper. And often the pedal had too low of an input impedance. Since they left the input connected to the source, you got some loading. Add a few pedals like this in a chain, and there goes your high end! So for those effects, true bypassing is an improvement.

But I think buffered inputs with some type of electronic switching is often better for your signal chain.
"You give a better performance if you skip the eyes" - Raymond Scott
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby Fuzzer » 27 Dec 2008, 21:24

Did you take any pictures??
The Freestompboxes Forum search function is soo great, use the search function..., the S E A R C H function.
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby DavidRavenMoon » 28 Dec 2008, 02:37

Fuzzer wrote:Did you take any pictures??


Of the Redeemer? No, it's potted in a small mu-metal can.

But you can look up the patent application for the schematic. it's quite elaborate.

20080068049
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby bajaman » 28 Dec 2008, 09:01

20080068049

is this the US patent number - cannot find any patentwith this number????
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby ianZeds » 21 Apr 2009, 13:24

I've recently started using a buffer in a true bypass chain of about 5-8 pedals depending on my mood/gig

I've built one of these in the middle of a patch cable
http://www.muzique.com/news/jfet-buffer-on-stripboard/

I use this buffered patch cable after the last fuzz in my chain, this means I can order pedals, swap and change as much as I like but avoid the tinny tone you get with too many true bypass pedals
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby noirengineer » 23 Apr 2009, 18:21

i know this may seem contrived, but, I believe it's more dependent
on where this buffer will work best in chain, TB and Buffered bypass
both have their place in the chain -- errr at least in my chain. for example.
the Klon. Now, just for arguments sake, let's argue the klon's architecturally
designed to be used as a signal buffer --> First in the chain of effects (perhaps
boosting another OD or fuzz in front of it). This is designation #1 usually seen used.
or typical designation type #2 is using the klon as a buffer after said OD / FUZZ.
yet.. not typically designed to be put in after mod/delay but before reverb FX.

So it's only natural that it'd perform well as a boost to vintage pedal.. yet, I've not yet owned a Klon myself,
but from various others who've i talked with about it's performance say doesn't play nice in
chain before any Germanium tranny effects, -- obviously with true-bypass, you've got dulling,
and sure, the argument is to place the germ before your klon, but still, isn't the solution a mix
of TB and Buffered pedals in a board a 'common' and accepted practice of most pedalboarders these days?

It's also worth mentioning that a 50 ft guitar cable plugged directly into an amp will have the same dulling type effect..
wire capacitance and distance the electrons must travel to reach your amp is what is at the root of the high end dulling.
IMHO.. all the buffered pedals do vs TB is give it a bit of a boost in signal before going to their next destination.
Useful sometimes... but if all pedals used this, it'd probably be moot.?


i don't know.. :roll:
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby earthtonesaudio » 23 Apr 2009, 19:26

I was just imagining how to bypass a true stereo (two independent inputs and outputs) pedal... If true bypassed, you'd need at least 4PDT, and that's without an LED. Buffered bypass lets you do the whole thing, plus LED, with a 3PDT.
rocklander wrote:hairsplitting and semantics aren't exactly the same thing though.. we may need two contests for that.
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby Rocket Roll » 23 Apr 2009, 20:12

bajaman wrote:
20080068049

is this the US patent number - cannot find any patentwith this number????
bajaman


USPTO Application #: 20080068049

http://appft1.uspto.gov/netacgi/nph-Par ... 0080068049
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby Brian M » 08 May 2009, 06:45

The biggest advantage of true bypass is that you know what you are going to get.
All buffers are not equal. If you look at a single brand like boss their buffers are not all the same.

My CH1 seems to cut highs a little. My DD3 bleeds a little bit of delay when bypassed. My old TS9 added white noise. My rocktron austin gold sounds dead when bypassed, which makes the overdrive seem even brighter than it actually is. My old boss hf2 would clip if i hit the strings hard enough when bypassed.

If most of your pedals are truebypass and a couple others have solid buffers you can at least control where those buffers are... I'm not sure all guitarists know enough to make an educated decision though.
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby gabrieln » 17 Jun 2009, 00:29

There was any great diference on using JFET or MOSFET buffers?

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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby Paul Marossy » 17 Jun 2009, 00:49

OK, I have to ask if anyone has read this: http://www.petecornish.co.uk/case_again ... ypass.html

I think he has some valid points. But I don't how many of them apply to the average joe guitar player that doesn't have a massive and complicated rig to deal with...
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby m0jo » 18 Jun 2009, 16:00

Holy crap, my head just exploded!! Reading the first page, especially the post by analogguru :shock:

Anyway, I tend to keep as much a possible true bypass.
My first pedal in the chain is the Ibanez Weeping Demon, which is buffered .. how well I don't know because it is impossible to find schematics :( maybe time to reverse-engineer that! :) It sounds fine though.

After that it's all TB except for the NS-2, SD-1 and in the FX-loop the DD-20 and two GE-7's.
(TB: EH Doctor Q, Big Muff USA, Green Big Muff Russian, SHO+Muff Fuzz :mrgreen: )

I'm looking for a proper loose buffer, since I'm aspiring to replace the Weeping demon soon.
Has anyone noticed the Toadworks Big Banana? It looks awesome!
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Re:

Postby Electric Warrior » 05 Jul 2009, 02:05

bajaman wrote:Regarding "vintage" pedals such as the Dallas Arbiter fuzz face and Solasound (colorsound) Tone Benders etc., these circuits had very low input impedances by today's standards, and severely damped the guitar's pickups, even when bypassed because all those guys did was switch the output on or off, while the circuit input remained connected and thus loaded the guitar.


Ronsonic wrote:Here's something I consider important that never seems to get addressed. All the vintage pedals had some amount of tone suck, some were severe. The answer was to simply turn the knobs on the amp. No problem. Now we come along and we take this Fuzz Face (a near perfect example) and we wire in a DPDT and the tone suck is gone and we can turn the treble knob down. Except now our FF sounds like a mudslide because the thing was originally voiced so that the effected tone was well balanced to the tonesucked sound and we got rid of that.


Sorry guys, but this is wrong. All these pedals you mentioned were true bypass with the circuit input grounded in off-mode.
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Re: True Bypass switching: myths, pro's, cons, alternatives...

Postby reubster » 07 Jul 2009, 07:34

This is a great thread guys.
Good to see all pros and cons thoughtfully discussed and especially ...understood..

It has saved me from a long-brewing rant regarding the blind stupidity of those who believe everything they read without asking or even wanting to know why.

Our friends at TGP and the like, all jumped on this TB [or is that "true boutique"] bandwagon: refusing to purchase any pedal unless it was TB, slagging off any pedals with buffers without even hearing/trying them [well, they didn't need to, because they weren't TB].
Then they paid big money to have all of their buffered effects [boss, ibanez and the like] converted into a true bypass form.
It took [what I thought] was a surprisingly long time before someone noticed/realised/posted that this long succession of jacks, plugs and patch leads resulted in sucked tone...Oh what a surprise!.. :slap: so then they rejigged the signal path with the addition of loopers and the like and now of course the the latest trend is buy dedicated buffer pedals to put back onto their boards to restore the tone lost by removal of the buffers in the first place.

on another note
There's an interesting discussion going on over at DIY Stompboxes regarding replacing TB style footswitches with flipflop FET arrangements [prompted by mechanical reliability issues with some footswitches].

I can see how this discussion will be interpreted at TGP ....... TB will be passe, the latest boutique pedals must all have FET switching and input and output buffers ......
HOT TIP for you fellow freestompboxers!... :secret: .... Get your soldering irons out, there will be some serious $$$ to be made when they all scramble to have their TB modded boss and ibanez pedals converted to FET switched & Buffered.
Just dont let on,... we are simply putting their pedals back to their original stock form.

Sorry, I guess that long-brewing rant still needed to come out.
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Switching pops

Postby sinner » 07 Jun 2013, 16:09

Guys, what makes clicks in true bypass switching? It is something related with DC current right?
The who? The fuckin' Who, that's who!
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Re: Switching pops

Postby Dirk_Hendrik » 07 Jun 2013, 16:54

..... multiple possible causes.... and even when thinking you've captured em... they still show up.

The ones I know most commonly:
- stray DC. This is the one where the pops are there when the box was just plugged in and go to minor over time.
- DC buildup. Where the in and out caps leak and build up mV's in the inputs. Usually resistors to ground work. Just as usually they do shit
- LED current inrush causes a temporarary DC drop on the suppluy voltage line which in turn results in pop.
- voltage fluctuation due to the switches resistance not being 0. Especially with switches having become dirt cheap this often happens.

And the best solution? Would be to change over to decent electronic switching instead of TB.. but tell that to the world..
Sorry. Plain out of planes.

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Re: Switching pops

Postby Mbas974 » 07 Jun 2013, 23:43

x Dirk "decent electronic switching" ....any good example ?
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Re: Switching pops

Postby modman » 18 Jun 2013, 09:06

Mbas974 wrote:x Dirk "decent electronic switching" ....any good example ?

Just look at your average Boss pedal...
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