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PETE CORNISH ON TRUE BYPASS

Discussion in 'Effects [BG]' started by MAGUS®, Mar 7, 2005.


  1. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    From the UK's king of custom FX boards...



    THE CASE AGAINST "TRUE BYPASS"

    "Hey Pete, do you use True Bypass?"

    Look out there's a lecture coming:

    The "true bypass" function, which is promoted by some, can create dreadful problems with a system that uses many pedals. Take for instance a 15 ft guitar cable linked to ten pedals, each linked by a 2 ft cable, and then onto the amp by a 30 ft cable. If all pedals have "true bypass", and are off, then the total cable length hanging on the guitar output will be 63 ft. This will cause a huge loss of tone and signal level particularly if the guitar is a vintage type with low output and high impedance. The amp volume is then turned up and the treble control increased to compensate for the losses. The inherent background noise now increases by the amount of the gain and treble increase and is usually, in my experience, too bad for serious work. If one of the pedals is now switched on, then it's (hopefully) high input impedance (and usually low output impedance) will buffer all the output cables from the guitar and the signal level will rise due to the removal of some of the load on the pickups (i.e.: 17 ft instead of 63 ft of cable). The treble will rise and the tone and volume will not be as before. If that pedal was say a chorus or delay, devices which are usually unity gain, then your overall signal level and tone will vary each time an effect is added...not a very good idea.

    Some pedals have an input impedance which is far from high in real terms; the input impedance of the vast majority of amps is 1 Megohm (one million ohms) and in my experience there are few effects pedals that have the same input impedance. A load on the guitar of less than 1 Megohm will reduce the volume and high frequency content of the pickup signal thus giving rise to complaints that "this pedal looses tone/volume" etc. Many effects I have tested have an input impedance of less than 100 Kilohms (ie: only one tenth of the amp input impedance) and cause serious signal losses in the effects chain.

    My system, which I devised in the early 70's, is to feed the guitar into a fixed high impedance load, which is identical to the amp input, and then distribute the signal to the various effects and amps by low impedance buffered feeds. This gives a constant signal level and tonal characteristics, which do not change at all when effects are added. The proof that this works are in the recordings of our clients: Roxy Music; The Police; Queen; Pink Floyd; Bryan Adams; Lou Reed; Dire Straits; Paul McCartney; Sting; Jimmy Page; Judas Priest; Black Sabbath....

    So the answer to your question re "true bypass" is no, I do not use this system in my Effects Boards/Racks as it can seriously degrade your sound. All my effects pedals which are derived from our large systems have, as the main input stage, a fiendishly clever pre amp that has the same characteristics as the input of a tube amp (1 Megohm/20pF), a highly efficient filter to eliminate the possibility of radio breakthrough and a low output impedance so that any following pedals/ cables etc. will not impose a load on the guitar signal. This pre amp is fitted to all our large stage systems and has always met with huge approval; not only from the guitarist but also the PA operator who is so happy to have constant level and tone presented to his mixing board. I go further with large systems and provide several inputs, each with the isolating pre amp and a gain compensation pre amp so that many different guitars can be level matched into the system. In addition a 20 segment PPM type display provides visual indication of signal level in our Effects Boards and Rack Systems.

    PETE CORNISH
    Unit 5, Silveroaks Farm, Hawkhurst Lane, Waldron, Heathfield, E.Sussex, UK, TN21 0RS
    Tel (0)1435- 813393, International - 0044 1435 813393, From US - 01144 1435 813393
    VAT Reg. No. GB 241 7291 72

    ©Pete Cornish 2003
     
  2. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Two foot cables to connect effects? :eyebrow: Most effects are not 1M? Most true bypass effects are at least 1M, it is the buffered effects (e.g. most Boss) that are not.

    Basically, what he is saying is that you cannot have 63' of cable without a problem. This is true. Get a buffer. Don't see what it has to do with true bypass though. :scowl:
     
  3. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    I'm afraid i didnt understand it either
     
  4. RAM

    RAM

    May 10, 2000
    Chicago, IL
    To me, it reads like someone who doesn't use true bypass to think of ways it's detrimental. But, with my eyes, that same scenario with NOT true bypass is not going to help the situation he described. I still fail to see why true bypass *hurts* the signal going from bass to amp. :confused:
     
  5. Heckxx

    Heckxx

    Nov 2, 2004
    Libertyville, IL
    made sense to me when i read it..am i missing something?
     
  6. I take it to mean true bypass ie. no electronics between input & output, just a straight connection, leaves the signal open to degradation along the way.
    and if there's a chain of true bypass pedals then the signal will be buffered by the first in the chain that's switched on, and the impedance changes due to which pedals are on can alter the tone.

    so his effect switching systems always have a buffer to meet the instrument signal, even in bypass= it's not a true bypass system.
     
  7. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    After rereading it, I can see his point. He wants consistency by having each effect always present the same impedence whether on or off. True bypass effects break this rule. They present a high impedence when on and no impedence when off.

    Note that the guitar loading point is moot since he could put the same preamp in front of the true bypass effects.
     
  8. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    I've read elsewhere about this, and the writer explained that he used a buffered pedal first in the chain, and TB pedals after it.

    Did that make sense to anyone ?
     
  9. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
  10. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Yes, this makes sense. The buffered pedal acts as the preamp that Pete Cornish uses. Assuming you don't have 10 pedals with 2 foot cables ;) then you should be ok.
     
  11. MAGUS®

    MAGUS®

    Dec 23, 2004
    UK
    That sounds more logical to me sean.

    2 ft cables though ? I dont know ANY player that uses such long FX ped cables.
     
  12. BassyBill

    BassyBill The smooth moderator... Staff Member Gold Supporting Member

    Mar 12, 2005
    West Midlands UK
    +1 on that.

    It seems to me that some players think "MUST have true bypass... don't want anything messing up MY tone" without questioning closely enough what it actually means. The words "true bypass" have an appeal for a reason that's fairly obvious, but unfortunately it ain't that simple.

    Got thinking about it and realised that a long chain of "true bypass" pedals won't magically preserve your pristine signal all the way to the amp... just the opposite, in fact. Surely if you're using a lot of pedals then true bypass is going to result in signal degradation for the reasons outlined above? Any chain that goes lead-connector-pedal-connector-lead-connector-pedal-connector-lead-connector-pedal-connector-lead-connector-pedal-connector-lead-connector-pedal-connector-amp (just 5 "true bypass" pedals!!) is going to have a lot more resistance/capacitance than a single lead of ordinary length, and hence mess up your signal. You're going to need some buffering (like from a pre-amp or your first pedal in the chain) going on, even with all effects off or "bypassed", to counteract this. Seems like true bypass may be a good thing from a sales point of view without necessarily being the best engineered solution, at least if you're using several pedals. Or have I got it wrong?

    PS I was thinking of starting a thread about this, and guess what... hey!! The search function works! Although I did have to just search just thread TITLES for "true bypass" to narrow down the number of hits a bit.
     
  13. Basstyra

    Basstyra Commercial User

    Apr 3, 2005
    France
    CTO @ Two notes Audio Engineering
    He is right for the 63 feet cable, of course. He's right for the buffer at the begining of the pedal chain, either. He knows what he's speaking about. But I don't see why condamn totally true bypass.

    Personnaly, I am against those who search absolutely for true bypass, there are other way to efficiently bypass pedals. But I have as many TB pedals as possible. I think some buffers only are enough, cascading buffers, that are not always good quality ones, unfortunately... can damage the sound, too.

    Because in fact, a buffer should only make the signal stronger, with less hiss, and so on. But... Buffers are physical systems, with bandwidth, a certain precision, active components, power (that can be hissy), and so, is as weak as a physical system can be. It can be great, or terribly bad.

    I put all in my LS-2 loops, and have about 3 TB and 3 non TB. Works perfect for me.
     
  14. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Boston, MA
    Does Pete's opinion still stand if one would be using a true bypass strip with their pedals?

    [​IMG]
     
  15. Basstyra

    Basstyra Commercial User

    Apr 3, 2005
    France
    CTO @ Two notes Audio Engineering
    The strip would reduce the length of wire, so reduce the signal loss. But with a cable before and one after, I think yes, it still stands.

    A buffer before the strip would be enough for me.
     
  16. emjazz

    emjazz Supporting Member

    Feb 23, 2003
    Boston, MA
    Is there a buffer that you'd recommend?
     
  17. BassyBill

    BassyBill The smooth moderator... Staff Member Gold Supporting Member

    Mar 12, 2005
    West Midlands UK
    That makes complete sense to me. I wasn't condemning true bypass pedals (or anything else I hope). Just pointing out that having a long chain of TB pedals won't guarantee no signal degradation. Also, avoiding the use of any sort of pedal that isn't TB doesn't necessarily make much sense - you need to think about how they all work together in the chain. ;)
     
  18. Basstyra

    Basstyra Commercial User

    Apr 3, 2005
    France
    CTO @ Two notes Audio Engineering
    Yep ! ;)

    Emjazz : well... I personnaly use the Boss LS-2 at this first place, just afte my bass. I think a good preamp (aguilar, sadowsky...) would be great.

    I don't think there are lots of buffer only pedals !! A clean boost is maybe the closest to a buffer (used without boost, of course...)
     
  19. Petary791

    Petary791

    Feb 20, 2005
    Michigan, USA
    Yeah, i've read that before. Pretty interesting stuff.

    If you care that much, just throw a preamp on there or something. ;)
     
  20. rockstarbassist

    rockstarbassist Banned

    Apr 30, 2002
    The Woodlands, TX
    Endorsing Artist: HCAF
    Having moved from a Loooper with "true bypass" (with 6 pedal, all Boss and 1 Ibanez) now to a Boss LS-2 line selector (with 5 pedals in the loop, and now my tuner before the LS-2), I honestly can't notice a lot of difference in my sound. Before, it was very noticeable when I'd switch the Loooper off/on, volume had to be adjusted per pedal, etc.. With the LS-2 now, there's no click and no volume jump. Granted I know you can get a Gain knob on most Looopers, but mine didn't have it.

    The article makes actually good sense to me. I wonder why guitarists don't have this problem... Most of them have anywhere from 3-7 pedals (on average), and seem to have minimal if no signal loss. I donno. :meh: