this1smyne buffer - WoW!! Dan knocked it out of the park!!

Discussion in 'Effects, Pedals, Strings & Things' started by Delayed Delay, Jul 10, 2011.


  1. Delayed Delay

    Delayed Delay Member

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    So I just got my t1m mini buffer in today (I also got the TB option as well as an external battery snap applied). I wanted it for the loop in my Maz as that loop sucks some serious tone; I lose virtually all bite from my guitars and it sounds like I've got my tone pot rolled pretty far down. I've had to compensate by cranking the cut and treble knobs on my amp, and then it just doesn't sound natural anymore, and still sounds muddy.

    Well, I decided that for $45, there really was no reason not to try the t1m mini buffer (I think it's only $35-$40 without the TB option; battery snap was free). I e-mailed Dan, and he responded by telling me several Maz owners have used the buffer for the same reason I described, and that they reported back positively as well.

    So I plugged it in tonight straight out of the send jack on my amp's loop, and from the buffer, I went to my board, and then back to the return jack of the loop. WOW! It actually sounded like I wasn't even using the loop anymore; my tone returned completely. Just to be sure my ears weren't playing tricks on me, I quickly unplugged both the cables in the loop (while the buffer was on), and kept playing - not a difference at all. Next, I plugged those cables back in, and turned the buffer off - tone was muddy and lifeless again. As I was playing, I unplugged the cables from the loop, and my tone returned. Lesson? The buffer works. ;) ...

    Here's a little demo I did. Now I'll preface this by saying I was rushed (wife was waiting in the car) and sleepy. So I said a few stupid things (really stupid things actually :)) and didn't think about what I was going to play. The idea is that you just hear the difference with the buffer off and then with it on. It's a little difficult to tell because of the compression in the video; I just used my iPhone's video camera, but hopefully you can tell the difference. If not, I'll give it another shot tomorrow when I have some more time. ;)



    No pedal dirt or effects... just guitar and the Maz's natural dirt. Signal chain is: guitar > dirt pedals > lo input > fx send > t1m buffer > mod/delays > fx return ... lots of cable in there (2 30' cables for the fx send/return), so this buffer helps a LOT!
     
  2. Delayed Delay

    Delayed Delay Member

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  3. reddog112

    reddog112 Supporting Member

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    Well done....a very noticeable improvement in tone! Congrats!
     
  4. mdclark58

    mdclark58 Silver Supporting Member

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    Dan's a good guy, and does quality work! Glad your experience was the same!
     
  5. chervokas

    chervokas Member

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    Yeah, an unbuffered effects loop is problematic. The send output impedance varies as you adjust the volume of the amp, and it can be pretty high, meaning you need to plug it into a device with a really high input impedance. Personally I think an unbuffered effects loop is not a great design idea for a guitar amp because you're plugging into guitar type effects typically with 500K ohm or 1 M ohm input impedances. Something like the T1M -- with it's very high 10M ohm input impedance -- is great for that application.
     
  6. CBeeper

    CBeeper Supporting Member

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    Just curious... any difference if you put the buffer at the end of the signal right before the return?
     
  7. Delayed Delay

    Delayed Delay Member

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    Thanks! I know my playing was weak... but in all fairness, I HONESTLY wasn't focused. I'll make up for it with some other demos. ;)

    Thanks for explaining some of the science behind it! Much appreciated.
     
  8. Delayed Delay

    Delayed Delay Member

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    BIG difference. I tried that too, and it didn't help much, if at all.

    I'd imagine that there would be a difference, because I've got 3 buffered pedals already in the loop, but they're on my board.

    There's a ton of theories to work with in this instance... but the way I look at it (courtesy of John Mayer :horse and many others) is my cables are like a water hose, and my tone is like the water trying to be pushed through the hose. After a while, the water is gonna lose pressure through the really long hose - the more cable I've got, the thinner and worse the signal/tone is gonna be.

    But by putting the buffer IMMEDIATELY after the send jack, it acts as another 'pump', so to speak, and pumps the signal through much more clearly than it would if it were having to pick up the signal from an additional 30 feet of cable (if it were on my board instead). It makes sense in theory (to me at least), and the theory actually works... ;)
     
  9. Whiskey N Beans

    Whiskey N Beans Member

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    Thank you for this information. I am adding delay and reverb to my Budda Twinmaster's effects loop. Currently there is only a Fromel shape EQ in there. And I've been struggling with the "best configuration for adding effects in. Sounds like it'll go Shape-Delay-Verb.

     
  10. chervokas

    chervokas Member

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    The hose analogy is really inaccurate and gives you a completely incorrect sense of what's going on here.

    As I already explained, in the case of an unbuffered effects loop the problem is often one of an impedance mismatched between the send's ouput impedance (which can be as high as 300K ohms) and the input impedance of the first active device in the loop. In order to avoid signal loss the input impedance of a device should be at least 10X the output impedance of the device feeding it. If you have the master volume down and the output impedance of the loop is like 275K ohms, then the input impedance of the first active device in the loop needs to be at least 2.75M ohms. No guitar pedal has an input impedance that high. Most have input impedances of 470K ohms to 1M ohm. So if you're sending a 275K ohm impedance signal into a 1M ohm input impedance device, or worse a 470K ohm input impedance device, you're going to have some signal loss, which is probably what you're hearing as tone suck with the effects loop. I don't really know that amp's circuit but I suspect that if you're running the MV cranked, the output impedance of the send is lower and as you turn down the MV the output impedance of the send rises.

    That's why a 10M ohm input impedance buffer like the T1M makes an signficant audible difference in the case of the unbuffered loop.

    With respect to cables between the guitar and the amp or a buffer or whatever the first active device is you have to think about it this way: The inductance of the pickups, resistance of the pots, and capacitance of the cable forms a resonanting circuit with a peak at a certain frequency (in the range of the guitar's upper harmonics) and a steep roll off of all frequencies above that peak. The more capactiance -- either by virtue of longer runs of cable or cable of higher capacitance per foot or both -- the lower the resonant frequency, the warmer and more mid focused the tone will generally be. The less capacitance -- either by virtue of shorter runs of cable, lower capacitance cable, or both -- the higher the resonant frequency, the brighter and more open the tone will generally be. The effect is more pronouced with lower inductance pickups (single coils) and lower resistance pots (250K ohm). A buffer at the front of a signal change can be used to effectively shorten the cable that loads the guitar circuit, since only the capacitance of the cable between the guitar and the first active device is part of the resonating circuit with the pickups and pots.

    The length of the cable, per se, isn't the issue, it's the total capacitance of the cable loading the gutiar. A 50-foot run of 25 pF/ft capacitance cable between the guitar and amp would sound the same as a 25-foot run of 50 pF/ft cable.
     
  11. Stratobuc

    Stratobuc Member

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    So if the capacitance is equivalent to the diameter of the hose, how is that analogy irrelevant?
     
  12. Delayed Delay

    Delayed Delay Member

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    Yeah... this.

    I understand the science of it much better now, but the hose analogy still seems to work on some level at least...:munch
     
  13. chervokas

    chervokas Member

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    The capacitance is not equivalent to the diameter of the hose. The amount of voltage, which is the signal, that is passing through the cable -- the pressure in the analogy -- isn't changing at all and isn't affected by capacitance. The resistance of the cable -- which is what would be akin to the amount of flow that can pass through a hose -- isn't a factor with the kind of current being produced by and electric guitar. The capacitance of the cable is really a byproduct of it's construction. It's not designed to be a capacitor, but because it contains two parallel conductors separated by an insulator, it functions as one in this instance.

    You need to think of the electric guitar with passive pickups connected to an amp via a cable as a little passive circuit made up of an inductor, resistor, and capacitor. That circuit will have a characteristic resonance based on the values of those elements. And that resonance, in part, will determine how bright or dark the system will sound. But the same voltage is passing through the cable either way and no part if it is being lost over distance. The circuit is more like a radio tuner than it is like a hose.

    It's wrong to think of guitar cable as being akin to a hose with signal traveling from one end to the other. In fact when you connect the conductor to the output voltage, that voltage is almost instantanously present across the conductor. (There actually is a flow of electrons but the flow of electrons is much, much slower than the actual propagation of the signal). Yeah, theoretically in electronics you can have signal loss over distance due to heat, and friction and stuff like that, but that's not a factor with guitar cable at audio frequencies over the short distances we use.
     
    Last edited: Jul 12, 2011
  14. justnick

    justnick Gold Supporting Member

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    As usual Chervokas is super clear and completely correct.

    A fluid analogy can sort of explain how an AC circuit behaves, but you have to refine the analogy quite a bit. An AC circuit like a guitar pickup--cable--amp input stage, is sort of analogous to a hydraulic system which is tasked with powering an actuator that has to continually reverse direction. For instance, one might imagine a hydraulically actuated that stirred a liquid by moving quickly back and forth.

    Such a system would repeatedly pump fluid in opposite directions in a closed loop that included lines (cable), a pump (pickup), and the actuator (amp input stage).

    Voltage=pressure
    amperage=rate of flow
    resistance=opposition to flow depending on the diameter of the line.

    Inductive reactance=opposition to the CHANGE IN DIRECTION OF FLOW caused by the inertia of the moving fluid and the friction of the line.

    Capacitive reactance=opposition to the CHANGE IN DIRECTION OF FLOW caused by the very slight expansion of the line as you begin to push in the other direction.

    These are NOT perfect analogies, but they can at least partly illustrate some useful principles.

    The issue of impedance matching can be illustrated as follows:

    --Imagine a pump that is a double cylinder with a single piston that draws in fluid on one side as it pushes it out the the other. Imagine the actuator as essentially the same sort of thing, though it isn't driven; it's moved by the fluid the pump is pushing. If the pump has a very large cylinder it will move a lot of fluid. If the actuator has a small cylinder, then there will be much more fluid than necessary to move it. You might think this situation would be optimal, but consider that not much fluid can flow back and forth because it's limited by the small actuator. This is analogous to an impedance mismatch where a very low impedance source is connected to a high impedance load. Not much current flows relative to the voltage available to make it flow, so not much power is available to be dissipated in work.

    In the opposite case, imagine a very small pump attempting to supply fluid to move a very large actuator. Now there's plenty of fluid CAN flow but for the pump to be able to supply enough to move the actuator, it would have to have a very long stroke and would expend quite a lot of energy to move that fluid. This is analogous to an impedance mismatch where a high impedance source is connected to a very low impedance load. Plenty of current can flow, but much of the power is dissipated in the source itself.

    BUT...if the pump's cylinder and the actuator's are the same volume, now for every bit of work you put into moving the pump piston, you get the same amount of work out of the actuator (of course some energy is lost to friction/heat). That is analogous to an impedance match, the most efficient setup if you want to transfer power between a source and load.

    The thing is that two of the three components of impedance (capacitive and inductive reactance) vary with frequency. So with an audio signal impedance mismatches and matches also affect tone.

    One can even extend the fluid analogy to cable capacitance. If you are familiar with hydraulics, you may be familiar with a component called an accumulator. It can store hydraulic pressure, but is also used to absorb momentary surges, or supplement pressure during momentary drops.

    An accumulator is basically a chamber with a membrane or piston across the middle of it. One side is exposed connected to the hydraulic system (circuit), the other has either compressed gas or pressurized hydraulic fluid in it. For clarity we'll consider an accumulator charged with nitrogen.

    An accumulator of this sort is analogous to a capacitor. If you apply hydraulic pressure to the system, the accumulator "charges" by allowing fluid to flow into it's chamber and further compress the nitrogen gas on the other side of the membrane. If you release pressure on the system, the nitrogen gas is free to expand and the extra fluid in the accumulator is forced out into the system again. This is all analogous to a capacitor in a DC system. If you charge it it stores static charge. If you then "release the pressure" by applying a ground, it discharges.

    Now consider if this accumulator was connected somewhere in our earlier system with a back and forth movement of fluid, and a reversing actuator. The accumulator would be somewhere in the loop, tapping off a line ("in parallel.") Everytime you pumped in one direction the accumulator would fill with fluid and compress the nitrogen on the other side of the membrane. When you reverse the direction of flow, first the pressure moving the fluid in the initial direction has to drop to zero. During this period the accumulator would begin discharge but since it has completely filled this would take some time. And in this example, it would not have enough time to completely return all the fluid that it had take in, before the pressure in the system built up again and began to fill it.

    If you think about this case in terms of how much "work" the accumulator is doing (by compressing the nitrogen over and over), it's not doing too much because it never really gets to full discharge and then recompress the nitrogen. So not much energy is being dissipated by the accumlator--it's just sort of sitting there and not bleeding off energy from the system.

    But if you were to speed up the alternations--make the pump move fluid back and forth very quickly--the accumulator would not have time to fully charge--just a bit of fluid would enter it, compress the nitrogen just a bit, then when the pressure direction changed in the system it could quickly empty itself, and then charge up a bit again as the pressure built up in the system. The membrane would be moving quickly back and forth--not a big distance, but very quickly. In this case we've turned the accumulator into an...actuator. It's doing a good bit work, compressing the nitrogen over and over. So at low frequencies this accumulator doesn't rob the hydraulic system of much energy. But at high frequencies it does.

    This is analogous (though not perfectly!) to what happens with a guitar cable. The center conductor is like the line in the hydraulic system that connects the pump (pickup) and actuator (amp input stage). The dielectric insulator around the conductor is like the membrane in the accumulator. The shielding is like the nitrogen on the other side of the membrane. And...these same three elements are those that make up a capacitor--two conductive plates separated by an insulator.

    A low frequency audio signal will not cause the capacitor to dissipate much energy to ground by constantly charging and discharging. But a high frequency audio signal will find it easy to make the capacitor into an "electron pump" that is dissipating energy by passing current to (and from--this is AC) ground.

    Again, this analogy is imperfect, but hopefully it can help one visualize some of the dynamics present. Hopefully I got it mostly right, even as an imperfect analogy!
     
    Last edited: Jul 10, 2011
  15. shikawkee

    shikawkee Mad King Edmund Gold Supporting Member

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    I use my buffer after my volume pedal before my Pigtronix Keymaster which I use for the effects loop. Dan's buffer is fantastic.
     
  16. Delayed Delay

    Delayed Delay Member

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    So I just realized I made 2 threads... whoops... anywho... I figured I'd answer this dude's question:

    I've also got the PSU available... but I had him attach an external battery snap because I've got the buffer sitting on top of my amp, and while I'm sure I can find a 9vdc adaptor for it, I'm not sure I can find one that's long enough to reach to a power strip. So the external battery snap allows me to power it on top of my amp, far away from my power supplies. :aok
     
  17. USCGAMCKS

    USCGAMCKS Member

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    I'm new to the buffer discussion. Given whay you say above, should a buffer go before or after a compressor?
     
  18. chervokas

    chervokas Member

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    It depends why you're using the buffer. All a buffer is, is a unity gain amplifier circuit used to convert signal impedance. We use them in guitar signal change to manage the effects on the guitar of the impedance loading of certain devices or of the capacitance loading of the cable. Is there some kind of issue with the input or output impedances of your compressor that you're trying to solve by placing a buffer in front of or behind it?
     
  19. this1smyne

    this1smyne Member

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    justnick and chervokas are my hero's. when a man has no time, knowledgeable peeps speak their mind. LOVE it. thanks guys.
     
  20. airbags

    airbags Member

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    okay, so i'm late to this party, and started a thread about a similar issue at hc, which lead me to t1m, which just created more questions than it answered :crazy

    both cbeeper and delayed delay are using their effects loops... well, i run my board in front of the amp... how would the buffer sound between the board and the amp?

    guitar -> board -> buffer -> amp.
     

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