The purpose/use of buffers

Discussion in 'Effects, Pedals, Strings & Things' started by jbgordon, Jan 8, 2008.


  1. jbgordon

    jbgordon Member

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    I've done a search, and can't really find anything about this.

    I have a few questions?

    1)What exactly is a buffer?

    2)In what instance should a buffer be used and why?

    3)What are some good buffers?
     
  2. jbgordon

    jbgordon Member

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    No one? Seriously?
     
  3. bulbasaur_85

    bulbasaur_85 Member

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    From what I've read and I'm not sure if I'm 100% correct, I think most people use buffered pedals within and at the end of their signal chain to maintain a level of signal - the signal is degraded over long runs of cables/effects so buffers are used to maintain a strong signal. Most Boss pedals are buffered. Please correct me if I'm wrong! because I know I am!;)
     
  4. aaland_brian

    aaland_brian Member

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    buffeers are used to help cope with long cable runs that dull sound due to high capatence loading down your guitars pickups, they are one of the bonuses of using electronic switching on pedals. The only real downside is that if you have too many buffers in your signal chain it may actually cause slight clipping. Their are some buffers that are created better than others but I still wouldn't want to many in your chain as it effects your tone. Their are buffers out their designed specifically to change the impedance of the signal to help it go through the chain without as much tone loss. Check out Axess BS-2 and VHT valvulator. The internet is full of information, you just have to go out and do a little digging. I think pete cornish had a good article about it on his site as well.
     
  5. amz-fx

    amz-fx Supporting Member

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  6. StompBoxBlues

    StompBoxBlues Member

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    Seriously...you searched THIS forum and didn't find anything about buffers?

    I just did an advanced search (the regular kind too...with the Google search in the upper blue bar you can even do better) with buffer in the subject header and had 91 hits.

    It's fine with me, these questions come up periodically, but asking a question that gets asked often here, which many folks have replied to many times, waiting one hour and then complaining "no one? Seriously?"...um...

    Buffers are an attempt to keep the signal level strong. Guitars put out so little signal, it can easily be lost, highs first. Cable runs, etc. and just simplt wanting to get all the signal across you can and send it stronger down the line.
     
  7. jbgordon

    jbgordon Member

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    My apologies for the impatience, and thanks for the help guys.
     
  8. StompBoxBlues

    StompBoxBlues Member

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    No problem. The basics of buffers are pretty simple, but I think dealing with then, finding the best interaction...it's like voodoo.
    Those links from amz are really nice, I've read them before. There are a few threads on this forum too that went into more detail.

    I would suggest clicking on a John Phillips post on his name and clicking the "show me all posts by this person" and looking for buffers references. Like he mentions, sometimes a huge advantage of buffers is sounding the same (so you can adjust with confidence the amp, etc.) whether pedals are on or off. With TB there can be more variance between the clean sound and a pedal on.

    Some, like in the Klon, work great with some pedals and way too ice-picky with others. I say that, using a consensus approach...I mean when you have a buffer that sounds good alone, then put it with another pedal that has a buffer and it sounds bad...it still could be either buffer (or just they don't mix!)...but this buffer often has problems in my rig with several other buffered...all of which don't seem to have problems with each other.
     
  9. pgissi

    pgissi Member

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    Buffers maintain the proper impedance within a signal chain and are used in all audio processing and specificaly designed to work with a high or low impedance signal.

    The best way to understand impedance is that it is a method to promote proper voltage transfer between devices and here are some everyday examples of impedance.

    If you can remember these basic rules, you will understand how to route signal cable for instruments, audio processing, sound systems or home stereo properly avoiding and minimizing hum and noise.

    Instruments with magnetic pickups are Unbalanced High Impedance (high Z weak signal source)

    XLR Microphone Cables are Balanced Low Impedance (low Z weak signal source)

    Home Stereo connections are Unbalanced Low Impedance (low Z stronger signal source @ -10dbu)

    Pro Audio Gear are Balanced Low Impedance (low Z highest signal strength @ +4dbu)


    These are audio signal transfer standards that used to manufacture gear for a specific application



    The rules-

    Balanced Low Impedance Signals can be driven up to 100' with minimal degradation with proper preamplification

    Limit cables runs for Unbalanced Hi (guitars) or even Unbalanced Low Impedance (home stereo) to under 25 feet with the upper limit possibly introducing hum and noise

    Impedance is reffering to voltage transfer


    Current transfer is then broken into High and Low signal Strengths

    High Signal Strength is broken into 2 categories
    Line Level -10 dbm
    -consumer grade home stereo, some low end audio gear

    Line Level +4 dbm
    -sythesizers, audio rack gear, sound and recording systems

    Low Signal Strength
    -instruments and microphones

    Now why does it sound like sheet when you plug your guitar/bass/mic into your home stereo aux inputs..... impedance mismatch.

    All are unbalanced signals but the guitar/bass/mic is a high imp source where the home stereo is a low impedance source

    Can you use a buffer to interface your guitar to your home stereo, simplisitcaly yes, but only if its designed to provide the proper impedance match to the input and output

    Balancing is the key to driving a signal through a long cable

    So your thinking well why not just convert the guitar signal to a balanced low imp signal so I can have 50 pedals and drive a 50 foot signal chain

    Its been done, its called the Les Paul Recording model but due to increased cost of making instruments and amps Balanaced Low Imp, it was never adopted by industry.

    Converting it is not a good solution since there is loss in the conversion using transformer coupling, a better way is to do what Les Paul did, Low Imp from pickups to amp

    I am just doing my part to rid the world of hum and noise and promoting proper impedance matching
     
  10. enditol

    enditol Member

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    Great post. It's really too bad balanced audio isn't the standard for guitar equipment, when it would potentially reduce noise and signal loss issues so much. Of course manufacturers will go for the cheapest route.

    I think Pete Cornish systems might use balanced audio and power connections.
     
  11. RGB

    RGB Supporting Member

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  12. pgissi

    pgissi Member

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    Yes indeed, check this out
    http://www.petecornish.co.uk/jptt.html

    Main Page- he has articles on true Bypass etc
    http://www.petecornish.co.uk/


    There is a solution if you can afford this high end and custom engineered gear. Too bad its not common place in the retail industry, it would sure elevate the capacitvely coupled electric arts.

    Right now synth/digital piano and keys players are really the only ones who consistently get a hum and noise free tone thanks to the use of Low Z Balanced +4dbu direct boxes which converts the Low Z Unbalanced +4dbu outputs of the synths locally at the players position and sends it to the FOH.

    Of course balanced outs can be built into synths, its a matter of cost and consumer expectations, they just want to plug into an amp and they are all high impedance inputs, no conversion needed there and only required for live performance into a sound system.

    For the rest of us suckers, were swapping buffering pedals, cables, ac adpters or batteries, kicking the stomps or amp mid way through a solo.

    If you understand the signal in your application and its susceptibility to emi, rfi, insertion loss, impedance mismatch and loading, your ahead of the game and can work through how to use buffering and true bypass to your advantage.

    What I really want to know is what a true low z balanced system would sound like for the high gain tones we have today or distorted guitar in general since Les was/is primarily playing clean I suspect the hifi nature of low z balanced works well there but may not with distortion and od.

    The key to driving an Unbalanced High Impedance weak signal from a guitar or bass is the use of a Line Driver aka a specialized buffer that is the first interface the pickups see, and from their a long chain of pedals is easily driven.

    Lastly, Pete dislikes the use of "all True Bypass" ironically, he is all about the strategic buffering. The bottom line in his opinion and mine is simply,

    "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"

    Translation, some strategic buffering is necessary


    For me (and I think Pete's from reading his info) in my small stage applications, its a combo of both buffering and true bypass in a specific order that I worked through to suit my needs, as long as your not using 20 true bypass pedals with your total signal chain length over 25 feet and no line driver (buffer) is used and the question there is.

    Whats the proper line driver to use in larger signal chains, I think Pete has the answer and I am guessing it high quality select componentry tested for tolerances and hand assembled then tested.

    Electric Guitar is one finicky cat
     

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