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Volume pedal question

beej

beej

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Personally I like the Jr, it's smaller (not small though, it's a good size). Personal preference.

Yes, with a Luke (or after a buffered pedal) you'll want the 25k version. You can try the other one and see how it works for you, the taper will be off but you might like it.
 
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marsguitars

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The smaller one still has a nice heavy feel to it (doesn't slide around like cheap plastic ones) - I use a 25k one in my effects loop rather than in-line with the guitar.
 
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martyhk0

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beej said:
Personally I like the Jr, it's smaller (not small though, it's a good size). Personal preference.

Yes, with a Luke (or after a buffered pedal) you'll want the 25k version. You can try the other one and see how it works for you, the taper will be off but you might like it.
Click to expand...

OK, HERES A STUPID QUESTION. HOW DO i KNOW IF A PEDAL IS BUFFERED?
 
beej

beej

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martyhk0 said:
HOW DO i KNOW IF A PEDAL IS BUFFERED?
Click to expand...
Not a stupid question at all! Normally the vendor will tell you - if it's "true bypass" (non-buffered) you'll see it listed somewhere. Else it's probably buffered.

You can tell by looking at the output specs- buffered pedals will have a low output impedance, usually less than 10 kOhm. For reference, all of the Boss pedals are buffered.
 
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martyhk0

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beej said:
Not a stupid question at all! Normally the vendor will tell you - if it's "true bypass" (non-buffered) you'll see it listed somewhere. Else it's probably buffered.

You can tell by looking at the output specs- buffered pedals will have a low output impedance, usually less than 10 kOhm. For reference, all of the Boss pedals are buffered.
Click to expand...

ok, here is my next stupid question. Why is the 25k pedal recommended if using a buffered pedal. I will almost always be using buffered as well as non buffered pedal(s) in my chain and the volume pedal will be at the end. And what if I change my setup and there is no buffered pedal? Can I still use the 25k or do I then have to use a 250k? I am totally confused and not sure what difference in sound will be due to the change in pot resistance.
 
beej

beej

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martyhk0 said:
Why is the 25k pedal recommended if using a buffered pedal ... if I change my setup and there is no buffered pedal ... Can I still use the 25k or do I then have to use a 250k?
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All good questions. Stop me if I'm nerding out too much here.

The guitar is an LCR circuit

A guitar's sound is affected by the electrical properties of everything it encounters. It's an "LCR" circuit- affected by inductance (L, a property of the wound pickups), capacitance (C, from capacitors used on the tone pot and shielded cable) and resistance (R, from wires and pots). Change any one property (like using a longer cord or higher value pots) and the frequencies produced by your guitar will be affected.

In a guitar, the pots used for volume and tone are said to be in parallel. They're connected to the signal at one end and ground at the other. When you have resistors in parallel you add them like so: 1/R1 + 1/R2 = 1/Rtotal. If you have two 500k pots in the guitar the total resistance is 250k.

Each one of these properties has a tonal effect

Typically, the higher the resistance, the brighter your guitar will sound (the "resonant peak" of the guitar's output is shifted to higher frequencies). That's why humbuckers, which are darker, use larger pots (R) to brighten them up while single coils, which are brighter, use lower pot values and don't need as much brightening. The humbuckers are darker because they have more inductance (L) which means they pass a smaller range of frequencies, and so on.

Normally the input impedance of an amp is very high (on the order of 1 MegOhm). From above, we know that it too affects the guitar's tone and would be in parallel with the other resistors. So now you have total resistance of 1/R1 + 1/R2 + 1/Ramp = 1/Rtotal. So- as the input impedance of the amp increases, 1 divided by this value becomes very low. That is to say, the guitar's signal is not "loaded down" by the amplifier, and so it doesn't suck tone from your guitar.

Okay, so what about the volume pedal?

If the guitar's signal hits something with resistance on the way to the amp, the signal will lose high end. (1/R -> the lower the R, the more the effect is noticable.) A volume pedal does this - it's just a pot, same as the volume pot in your guitar.

A 250k volume pedal is like another 250k pot in your guitar. It will load the guitar some and affect your tone slightly. But a 25k volume pedal will drastically reduce the resistance and thus take off a lot of high end.

That's why you don't want a 25k volume pedal for a passive guitar or non-buffered signal.

Active, passive and buffers

Active guitars (have an on-board amplifier) have much lower output impedances than passive ones. One of the advantages is that you can drive a lot of cable without any loss of high end (the capacitance of cables is a problem with the higher impedance passive signal). The frequency curve of the guitar isn't affected by the passive electronic components down the line. (You can also use an on-board amp to mix the signal from magnetic and piezo pickups, like on some of the MM guitars -> the blended output is active.)

A buffer serves much the same purpose- it has a high input impedance for a guitar (so as to not affect the tone too much) and it's output is low impedance. Basically acts as an external pre-amp, but doesn't chance the volume.

For active and buffered signals, you don't need to worry about the tone suckage from an external volume pedal like you do with a passive signal.

So why use the 25k pedal with an active/buffered signal then?

Taper. Again, it's the parallel resistance thing. As these loads act on each other they'll have an effect. Here, the effect will be to change the sweep of the volume pedal so it's not as smooth as you expect. Using the 25k volume pedal here will provide a more useful taper.

So what do you do if you have both active/buffered and passive?

Good question. Some think the best bet is to put a buffer in line with your signal. A good high quality buffer (Boss pedal included) will allow you to drive longer cable runs without losing high end. And then your signal won't be loaded down by the volume pedal the way the passive signal would be.

But you can also go the other route and try the 250k pedal with the active signal. I haven't tried, so not sure how the taper will be.

Or ... you can just use your guitar's volume pot for volume swells and not use a volume pedal at all. Or just the FX loop to control overall amp volume.

Anyway ... very wordy response here ... hope this was useful.
 
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Spudmurphy

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There will be an exam on this on Monday, so I want you all to revise this.

There will be no excuses for not taking the exam.

- and no Travs if as you say "what would happen if I had a night of unadulterated 5ex and passion would I still have to sit the exam?"

I'm afraid the answer would be yes - because you could still write the exam with the other hand. :D
 
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travs

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Spudmurphy said:
There will be an exam on this on Monday, so I want you all to revise this.

There will be no excuses for not taking the exam.

- and no Travs if as you say "what would happen if I had a night of unadulterated 5ex and passion would I still have to sit the exam?"

I'm afraid the answer would be yes - because you could still write the exam with the other hand. :D
Click to expand...

I will take the 'F' I am too sore and exhausted. and besides that quantum physics stuff is for the pros.
 
roburado

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So, let's say I want a volume pedal for both the overall volume and for the effects loop. If I've got passive electronics, I need the 6180 for both, right? And if I get a Luke, I want the 6181 for both?

Man, that's a lot of pedals. :eek:
 
Spudmurphy

Spudmurphy

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Colin

Off topic I know but if it's any use - we've had threads asking how to remove tremolo arms (and opening cases!! ;)) so here is a small video clip showing how to do it.

It may be useful - it may not.

Click on the image to play it.

 
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