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the-destructor
Silver Member
USA
334 Posts |
 Posted - 11/15/2008 : 03:33:49
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Questing & trolling for volume pedal input. I own one, but it is best suited as en expression controller. What do you love & why?
 T-D |
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DeFrag
Moderator
USA
3409 Posts |
Posted - 11/15/2008 : 05:45:05
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| I went with the Boss FV-500H that doubles as an expression pedal for my Moog effects. I wanted to get the FV-500L with its stereo-outs & modify it with a switch between low & high impedance but alas, I did not. I LOVE the tank that is the FV-500. |
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Right Foot Boss
Gold Member
USA
881 Posts |
Posted - 11/15/2008 : 06:28:35
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A related question about this that I have had for some time now is the difference between high and low impedance.
In best layman terms what is it? |
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DeFrag
Moderator
USA
3409 Posts |
Posted - 11/15/2008 : 07:09:07
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Impedance is a measure of opposition to time-varying electric current.
Impedance matching is the electronics design practice of setting the output impedance of a signal source equal to the input impedance of the load to which it is connected, usually in order to maximize the efficiency of power transfer and minimize reflections from the load.
In general audio as relevant to our use, passive pickups require high impedance characteristics in order to minimize current loading on the coils which would manifest itself in frequency losses & perhaps even lower output amplitudes. For instance, a DI (Direct Injection) box is typically used to connect a bass guitar directly to a mixer. The DI box takes the high impedance side & converts it to the lower impedance expected by the mixer input. Low impedances are also required for long cable runs to minimize signal losses & are standard for mic-level sources.
You'll notice that the inputs on Boss effect pedals are high impedance whereas the outputs are low impedance. I've always wondered about a chain where the 1st pedal output is a low impedance feeding into the 2nd pedal input which is high impedance. Apparently there is no concern or little consequence as most pedals are buffered (amplified) anyway & the short runs are a wash. |
Edited by - DeFrag on 11/15/2008 07:11:37 |
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gurran1928
Gold Member
Sweden
650 Posts |
Posted - 11/17/2008 : 08:39:21
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| I like the FV 100. |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 11/17/2008 : 09:13:05
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quote:
Originally posted by DeFrag
Impedance is a measure of opposition to time-varying electric current.
Impedance matching is the electronics design practice of setting the output impedance of a signal source equal to the input impedance of the load to which it is connected, usually in order to maximize the efficiency of power transfer and minimize reflections from the load.
In general audio as relevant to our use, passive pickups require high impedance characteristics in order to minimize current loading on the coils which would manifest itself in frequency losses & perhaps even lower output amplitudes. For instance, a DI (Direct Injection) box is typically used to connect a bass guitar directly to a mixer. The DI box takes the high impedance side & converts it to the lower impedance expected by the mixer input. Low impedances are also required for long cable runs to minimize signal losses & are standard for mic-level sources.
You'll notice that the inputs on Boss effect pedals are high impedance whereas the outputs are low impedance. I've always wondered about a chain where the 1st pedal output is a low impedance feeding into the 2nd pedal input which is high impedance. Apparently there is no concern or little consequence as most pedals are buffered (amplified) anyway & the short runs are a wash.
Taking it somewhat off topic for a minute 
As you noted, matched impedance gives maximum power transfer. This is important when you are transfering substantial quantities of power around, like in a power-amp to speaker connection.
In pedals, however, the thing we are most interested in is signal transfer. Assume the guitar is input to a high impedance pedal input (pedal #1) - the pickups won't be loaded down and will perform as required. Now imagine a second pedal connected to the output of the first pedal (pedal #2). Here are two situations that illustrate the concept.
Situation 1: Assume the pedal #1 has a low impedance output and that pedal #2 has a high impedance input. In any circuit like this the maximum voltage is developed across the highest impedance in the circuit. If pedal #2 has an input impedance 100 times bigger than the output impedance of Pedal #1, then 100/101 of the signal will be applied to the input of pedal #2 (and 1/101 of the signal will drop across the output of pedal #1).
Situation 2: Assume the pedal #1 has a high impedance output and the pedal #2 has a high impedance input. Again, the maximum voltage is developed across the highest impedance in the circuit, but if both pedals are the same impedance, then half of the signal will be applied to the input of pedal #2 (and half of the signal will drop across the output of pedal #1)...
Summary
In situation 1 the input voltage to pedal #2 is 100/101 (or close to 100%) of the output of pedal #1. And 100% = no signal loss.
In situation 2 the input voltage to pedal #2 is 50% of the output of pedal #1. And 50% = 3dB signal loss.
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Edited by - Laurie on 11/17/2008 09:21:21 |
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DeFrag
Moderator
USA
3409 Posts |
Posted - 11/17/2008 : 09:57:47
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Tks for the explanation by example Laurie!  I knew low-impedance outputs were there for a reason but didn't have the numbers to explain it. I was hoping you'd step in here. |
Edited by - DeFrag on 11/17/2008 09:58:14 |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 11/17/2008 : 12:31:09
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I had a lend of an ernie ball volume pedal for a while...pretty good for what it did..i can't remember the model,it was a good while back so i reckon it was the original one,i know some of the top guys swear by the Sho Bud pedals if you can get your hands on one,mostly used by steel players..but i think the ernie ball is the most widely used......
Nice one on the impedance thing guys..... |
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zentropa
Gold Member
USA
837 Posts |
Posted - 11/17/2008 : 16:27:30
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quote:
I had a lend of an ernie ball volume pedal for a while...pretty good for what it did.
out of the standard readily available non-boutique volume pedals, i've found ernie ball to be the best of em... at least vs. the other stuff that is available at most music stores. |
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PaulH
Gold Member
535 Posts |
Posted - 11/17/2008 : 21:38:25
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I had a FV50H and hated it.
Made of rubbish plastic.
The volume curve/swell came in way to soon.
I'm sticking with my trusty FV300H |
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FRANZONI
Double Platinum Member
Ireland
3543 Posts |
Posted - 11/18/2008 : 16:35:11
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| I ment to say that the reason i never bothered with one in the end was i got into Danny Gatton who uses the volume on the guitar for swells and violining on notes and i also forgot a few times to push the volume pedal up with my foot..... i've gotten so used to the strats volume control that it would be hard for me to change i think..... |
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Topic |
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Best volume pedal? and why
