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RANT: Internal Trim Pots


mrbassie

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Why oh why must companies put internal trim pots on the INSIDE of pedals?

 

My Fulltone clyde wah - 4 pain in the $#@ screws embedded inside rubber feet to get to the bass/treble internal trim pot. Look at all the room everywhere to put a external switch. How about drilling a hole large enough for a flathead and a rubber plug!?

 

So I was thinking about getting a Barber Tone Press only to find out there is another internal trim pot. How do you know you are getting the sound you want without exploring all possible configurations? You just HAVE to go in there and adjust it.

 

That or spend $100 extra for the Keeley 4-knob compressor :idk:

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Some trimpots are crap, they cut out your sound completely unless theyre in exactly the right place, or they don't do anything at all. I messed up my Yamaha flanger cause it had 4 internal trimpots and i didnt mark them before changing them and now i havent a clue what it should sound like.

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Some trimpots are crap, they cut out your sound completely unless theyre in exactly the right place, or they don't do anything at all. I messed up my Yamaha flanger cause it had 4 internal trimpots and i didnt mark them before changing them and now i havent a clue what it should sound like.

 

 

Thats the point of them so there not crap. trims are variable resistors used for biasing components.Once set they don't need to be touched.

 

I use them to bias fuzz pedals because the right value resistors don't exist for what i need and a trim is easy, it gets spot on every time and allows me to hear the exact spot/what i want it to sound like.

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how dare those builders give you the ability to tweak their pedal to fit your rig. what were they thinking?

 

 

You are missing the point entirely. I love that we can adjust a pedal. The point is with the fulltone wah and barber tone press, for example, there is SO much room to put the pot external for EASIER adjustment. I adjust the internal trim on my fulltone wah pedal all the time it just becomes a nuisance.

 

Keeley 2 knob comp. Why in the world would the attack trim be internal?

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You are missing the point entirely. I love that we can adjust a pedal. The point is with the fulltone wah and barber tone press, for example, there is SO much room to put the pot external for EASIER adjustment. I adjust the internal trim on my fulltone wah pedal all the time it just becomes a nuisance.


Keeley 2 knob comp. Why in the world would the attack trim be internal?

 

 

point taken. i guess some adjustments only need to be made once and then you can forget about it but

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i need to get the dmm tuned up, it has four or five i think.

 

 

 

 

DO NOT TOUCH THEM. The DMM has to be one of the hardest (if not impossible)

pedals to calibrate by ear. I guess the only thing worse would be an AD999. Seriously you will try for hours and then just end up sending it to Howard Davis. You need an Oscilloscope and a calibration procedure. I have the calibration procedure and even with an oscilloscope it is no easy task.

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DO NOT TOUCH THEM. The DMM has to be one of the hardest (if not impossible)

pedals to calibrate by ear. I guess the only thing worse would be an AD999. Seriously you will try for hours and then just end up sending it to Howard Davis. You need an Oscilloscope and a calibration procedure. I have the calibration procedure and even with an oscilloscope it is no easy task.

 

 

Where did you find the calibration procedure?

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DO NOT TOUCH THEM. The DMM has to be one of the hardest (if not impossible) pedals to calibrate by ear. I guess the only thing worse would be an AD999. Seriously you will try for hours and then just end up sending it to Howard Davis. You need an Oscilloscope and a calibration procedure. I have the calibration procedure and even with an oscilloscope it is no easy task.

 

 

Good advice, and thanks for the recommendation.

 

Trimpots are necessary to allow the factory technician to set up the pedal to work properly. The delay chips and certain other parts vary considerably unit to unit, and trimpots allow an adjustment range so all pedals work and sound the same. They are on the inside because the user should NOT tamper with them.

 

Guitar pedal design engineering, repairs, and custom mods:

http://howard.davis2.home.att.net/

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trim pots in pedals can have two purposes.

1 factory adjustment to work correctly

2 user adjusable to tweak.

 

-in the case of factory adjusted pots, they are often used to bias stages, or compensate for wide tollerances of parts used... i believe the tonepress is a jfet compressor. Jfets can vary quite a bit, and in order to work correctly in a circuit often require either a much larger circuit to compensate for the jfet, or simply use a trim pot to adjust for the variations.

 

-for user adjustable pots, in many cases, many users may be uninterested in every touching them, or may just find their spot, and never mess with them again. Some people like to have a lot of options to tweak their pedals... trim pots allow the maker to make a smaller pedal where the people who dont want to tweak their pedals that much dont have to pay so much for all the extra knobs and the extra floor space.

 

It's a compromise, and sometimes it makes sense after you weigh the benefits vs the extra cost of all the extra knobs and space taken up.

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Trimmers can be a freebee. Sometimes one can replace two resistors -- vs. making it external and adding components to limit the range, maybe more to make it not crackle, and still end up being way less effective than the other knobs.

 

As to the wah, maybe fulltone thinks adding knobs external will be a turn-off for those comfortable with the simplicity of the normal wah.

 

To adjust trims, look up in the user's manual what it does and how to adjust. If it doesn't say anything, you're too lazy to look, or it says don't adjust, don't.

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