Photo-cell pedal Vs Pot type?

Al Marcus · From: Cedar Springs,MI USA (deceased)

I did an A-B test with a Goodrich light beam photo cell volume pedal and a Pot type pedal.

Although the pot pedal was very good. There seemed to be a difference to me.

The photo Cell sound was clean and clear and the tone did not change, full on or less.

It also seemed to take less power from the amp, in effect making my small amp sound more powerful.

This is not a scientific test, just my own impressions. I just plugged the guitar in one pedal or another with no other changes.

I am curious if anyone else has tried this test, and what were your impressions?...al

Jack Stoner · From: Kansas City, MO

Al, you say "It also seemed to take less power from the amp, in effect making my small amp sound more powerful"

How can an external device "suck power" from an amp?

The difference in volume level is due to the fact that most pot pedals do not have a 1:1 gain at full volume so there is some signal loss and probably the photo cell unit has some amplification in it, or at least no loss, and with the higher signal you were getting more volume out of the amp.

Al Marcus · From: Cedar Springs,MI USA (deceased)

Jack- It sounds like you have it figured out right. I just maybe should have said the photo cell pedal seemed to have a little less loss in volume?.....al

Chip Fossa · From: Monson, MA, USA (deceased)

Al,
While I have never done a side by side test as you have mentioned, I have owned/played both types of Goodrich pedals.
Lightbeam & pot.

This is just my preference, but the LB seemed
to have a harsher quality to it [like what you are saying about it seeming louder, drawing more volume]. I just didn't care for the way, I also thought, that it altered the tone. Whatever my tone settings were, they were altered by the LB. When the pot pedal was put back in, the sound was much smoother
and not as 'in-your-face'. I had both pedals
at the same time, however, I never really sat and switched them back and forth. I just would play thru one or the other for a week or two, and then, gradually the difference between the 2, was becoming more and more apparent. IMHO, I just favor the pot over the LB.

chipsahoy

Donny Hinson · From: Glen Burnie, Md. U.S.A.

I don't think there's so much a "loss of gain" with a pot pedal, rather there is "an increase in gain" with a photocell pedal, due to the powered electronics (preamps) in them. With a 1/2 Meg. pot, there probably is negligible loss of gain when the pedal is wide open.

Jack Stoner · From: Kansas City, MO

Pot type pedals can have a lot of "loss" at max volume, and have as much as 25% of the pot resistance remaining at max. This is due to how the pot was initially set, the physical travel of the volume pedal, etc.

Keith Hilton first mentioned this as common among pot pedals and having worked on many pedals over the years (replacing pots) I had never given it a thought.

But I measured my Goodrich 120 and found there was 70K ohms resistance at the "max volume" position. I was able to get it down to about 2K ohms by removing some slack from the string. I have a Goodrich L120 and it too had quite a bit of resistance left at max volume and by working with it I was able to get it down to about 5K. If I set them at 0 resistance then they would not completely shut off so it was compromise and I went for the shut off. I can live with the 2K and 5K at max.

Bob Knight · From: Bowling Green KY

Wayne Wallett · From: Shermans Dale, PA USA - R.I.P.

Have had Photo, reg pot and pot no loss
new one from Goodrich. For my money the Pot No Loss is the best, no tone change from low to high. No power loss. A friend of mine showed me on a scope that about 20% is lost on pot pedal when wide open without the no loss circuitry. No Loss means what it says...100% in and out. Just my preference...
Wayne

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

A light beam pedal is a pedal that contains a Cds cell. A Cds cell acts like a variable resistor reacting to light and darkness. It is the same thing that turns on street lights at dark. Cds cells are excellent for transmission of audio signals. Poor sound quality occurs when they are not arranged properly. Sound quality depends on the guy who designed the circuit! The "biggest" mistake is not using a pre-amp, and putting it in the right place in the circuit, although there are many other "pit-falls" in designing a circuit using Cds cells. One major problem is ambient light. Since pedals are made of two parts, with a huge open space between the two parts, ambient light can enter. This becomes a problem in bright sun light, or on a brightly lit stage. Many of the light beam pedals would not go all the way off in bright light.
Let me again say that Cds cells are excellent for audio, if the circuit is designed correctly. Let me point out something; My infrared pedal is "NOT" a light beam pedal. My infrared pedal does not contain a Cds cell of any kind. My infrared pedal contains no pot. It is therefore different from a light beam pedal and different from a pot pedal.

[This message was edited by Keith Hilton on 02 March 2001 at 09:13 PM.]

richard burton · From: Britain

Jack Stoner:
Why do you want your volume pedal to shut off completely? In my opinion this is fatal for tone. I have at least 20% volume going through when my pedal is at minimum.

Jack Stoner · From: Kansas City, MO

Richard, when my volume pedal is in the "off" position I do not want any signal from the steel. That is the "normal" setup on a volume pedal manufacturers and how most people want their pedals setup.

I used to do amp repair in Nashville and replaced a lot of pots in pedals. Everyone wanted their pedal setup so that it was "off" in the off position. I never had one request for anything different.

Your setup is not the usual setup but it is yours and you can adjust it however you want.

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Good point, Jack. Also, if your pot pedal won't go from full-off to full-on, there are two ways of correcting this problem. Modify the pedal for more travel, or reduce the size (diameter) of the pot's pulley. This can be done with a lathe, or (in a pinch) with a drill and a file. The preferred setup is, as Jack said, to go from full-off to full-on.

Steve Feldman · From: Central MA USA

Well - maybe it's just me, but I don't feel like hassling with sending the pot pulley out to a machine shop for turning. However, at the same time, I DO find it extremely frustrating that of the 3 pedal I have, not one opens and closes fully with the string-controlled pot. The Emmons I bought not too long ago is particuarly bad. There is no way to get that pot open fully without having the derned thing also stay 'on' at the pedal off position. I've got it set to where it's tolerable, but I am loosing a lot of signal. Still seems like 'caveman' technology to me...

Lee Baucum · From: McAllen, Texas (Extreme South) The Final Frontier

You're right, Steve. This whole pot pedal thing really is "caveman" technology. There must be a better way of making a volume pedal. Hmmm.

Lee, from South Texas

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Jack, there is a control on the bottom of my pedal that sets the on and off starting point. You can set this control where the pedal will go off ,or on, at "any" point. You can leave as much sound "on" in the "off" or back position as you want. Jack, I'm like you, I like my pedal to go all the way off. This has been my experience; about 60% like the sound to go all the way off. 40% like a little sound left on in the off position. Just my observation from talking to customers. Don't matter what you like, you can get it instantly by turning a adjustment on the bottom of my pedal. That is a lot easier than fighting strings and pulleys. Just my opinion.

Steve Feldman · From: Central MA USA

Keith - get rid of that wall wart, and I'll be knocking at your door.

Steve 'Caveman' Feldman

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Steve, I wish I could get rid of the wall wart. If something draws over 5 to 10 mili-amps it is really not realistic to use battries. Two good 9 volt battries cost around $4.50. Two good 9 volt battries have a life of about 125 mili-amp hours. If the device drew 40 mili-amps, then you would divide 40 into 125 to see how much time you would get out of your $4.50. Dividing 40 into 125, you get a little over 3 hours. This means your battries would run down in a little over 3 hours. Any device that has any kind of "light" draws quite a bit of current. One solution to wall warts and batteries is the passive potentiometer, or pot. Some people compain about the cost of gasoline for their car. One solution, but not a perfect solution, is to get a horse. Just kidding Steve.

[This message was edited by Keith Hilton on 06 March 2001 at 10:53 AM.]

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Anyone "stuck in the stone-age" (like myself) might want to try an old Fender (pot-type) volume pedal. I have tried most other pot pedals, and (IMHO) nothing even comes close.

(If I ever buy a powered pedal, though, you can bet it will be a Hilton.)

Keith Hilton · From: 248 Laurel Road Ozark, Missouri 65721

Thanks for the kind words. Here is something interesting concerning battery life. I just bought a Boss DD3. I usually use a Peavey ProFex II when I perform out. I bought the Boss DD3 for two reasons. If my ProFex II every quits working I will have the DD3 for a emergency. I also bought it because a lot of people use it with my pedal. They are always asking me about hooking my pedal to a DD3. Now that I own one, I can give a much more informed answer. I was reading the DD3 instruction papers ,and it says the DD3 draws from 45 to 65mA at 9volts. mA means mili-amps of current. The instructions then said a manganese battery would last from 30 minutes to 2 hours. A alkaline battery would last from 5 to 10 hours. I really don't understand their math. If a alkaline battery lasted 5 hours ,and the DD3 drew 45mA. Then you would multiply 5 times 45 and get 225 mili-amp hours in the life of a 9 volt alkaline battery. I thought most 9 volt batteries were rated at 125 mili-amp hours? Is my math wrong ,or don't I understand how 9 volt batteries are rated? In reading the instructions I didn't understand the use of the HOLD function? Could someone who uses a DD3 unit tell me what the HOLD function does? I also noticed in the instructions it said: "System--Analog logalithmic compression and 12 bit quantizing system." The front must be analog before it goes to the DSP.

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