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Topic: Vol pedal problem |
Tony Harris
From:
England
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Posted 18 Feb 2000 4:46 am |
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| I have an 8-string lap steel (an Otwin). Plugging direct from the guitar to an amp - there are no controls on the guitar - gives an INCREDIBLE amount of treble. This is not a problem as I want a bright modern sound (like a pedal steel, rather than the mellower old 40s/50s western-swing tone). Plugging through my Goodrich pedal softens this down a little -this is fine but there is a tonal difference across the pedal's travel - the last little bit really brightens up. I guess this is something to do with the impedance of the pickup (which I don't understand). Is there a modification I can do to help this? |
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Jack Stoner
From:
Kansas City, MO
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Posted 18 Feb 2000 5:34 am
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Tony, that is typical of what happens through a volume pedal, because of the potentiometer that is in the pedal reacting with the pickup. On some pickups, the volume pedal has little or no affect on the tone, on others such as your case it has a noticeable affect.
You can minimize this by using a buffer device, such as a Goodrich Matchbox, Hilton Digital Sustain unit or an MXR Microamp (and probably other similar units). They all perform signal buffering and a low impedence output (plus some do other things such as a tone control).
Another approach, if you have an amp with a volume pedal input/output such as a Peavey Session 500 or a Peavey Session 400 that uses the effects loop for that same purpose. In those cases, the guitar is connected directly to the amp input and then the volume pedal is run in the effects loop. This eliminates any affect the volume pedal has on the tone.
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 19 Feb 2000 5:18 pm
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| I thought all the Goodrich pedals were lightbulb/photocell units? If this is the case, it doesn't have a potentiometer. If it's an "old" pedal ("old" is 10 years or more) it probably isn't up to today's standards anyway, or it could be going bad from age. Unless you're sentimentally attached to it, get another pedal. It's probably not worth the $50 or so it might cost to fix it. |
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ajm
From:
Los Angeles
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Posted 19 Feb 2000 8:38 pm
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If it's a passive pedal with just a pot inside and no other electronics, trying the ol' "capacitor on the input to wiper of the pot" may make the range seem more evenly tapered. This way when you turn down the volume the highs will not seem to disappear like it sounds like they are doing now. Then you can adjust the EQ at the amp to get the basic balance that you want. (I am going to assume that you don't know much about electronics. If it seems like I am talking down to you here that is not my intent.)
To do this mod open up the pedal. There are 3 terminals on the pot: one from the input jack of the pedal, a center terminal that connects to the output jack, and one that most likely either connects to the case or is soldered to the bottom of the pot (same thing electrically). All you need to do is add a small value capacitor on the pot from the terminal connected to the input jack to the center terminal (output jack) of the pot.
The pot in the pedal is most likely between 250K ohms and 1 Meg ohms. (If it's a smaller value pot, which is unlikely, then this may be your problem.) Go to Radio Shack or any electronics supply store and buy an assortment of cheap capacitors. Ceramic disc types will work fine and you can usually get a pre-packaged assortment for way less than 5 bucks. You will probably only need values from about 300 picofarads (pf) up to about 1500 to 2000 pf. Start with about 1000 pf and work up or down from there as your ears tell you. You can attach some clip leads to the two terminals and try different values (without soldering) until you find the one that you like. When you find the right value just solder it in. As long as you turn the volume down before changing caps it is almost impossible to hurt anything.
The caps will probably be marked in picofarads with three numbers. The first two are for real; the third is the number of zeroes after the first two. 1000 pf would therefore be "102", 330 pf would be "331", and so on.
Whenever I get a new 6 string guitar or work on one for a friend I always do this modification inside the guitar. Most manufacturers don't do this and it costs a grand total of about 2 cents.
Hope this is the solution. |
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Jack Stoner
From:
Kansas City, MO
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Posted 20 Feb 2000 3:22 am
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Donny, the Goodrich 120 and L120 pedals are the standard 500K pot type volume pedals. Goodrich made a light beam pedal years ago, but I don't think it's made anymore.
Goodrich also has newer models 10K and L10K that have basically a matchbox in them and use a 10K pot.
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