Pro-197 Volume Control

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poppafred

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May 5, 2005
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I have had problems with the volume control on my Pro-197 since I bought it. It is very touchy and just 1/32 of a turn can take it from inaudible to blaring.

Tonight, I shifted the external speaker from the rear jack to the headphone jack. What a difference! What used to take just a touch now takes 1/4 turn. So much nicer.

My question is, should I worry about burning something out by using the headphone jack all the time? I know it sounds silly to some of you but I figured it wouldn't hurt to ask. Better safe than sorry and all that. I have no idea how well built the audio circuit is for the headphones and guess I am looking for reassurances that it won't mess something up.
 
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So Far Away....
in short,
No..

the H-Phone jack is your output,there is no draw on the line like with,,lets say....your house-where you if you put too much load on the circuit the breaker trips/or wiring burns up(mostly hoping the breaker trips...lol)
there your deallng with amps/volts..

the speakers a purely power driven,they will only give response to what theyre being fed with,,watts n ohms n such,,your more likely to blow the headphone/ext speaker...

now if your talking about your mic/audio input
Yes,you rcan over power that.and that can result in blowing your soundcard..

no clue as to the cause of your hinky volume dial..

cheers mate!
 

sjlamb

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May 27, 2007
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Location
Sarasota County, FL
no clue as to the cause of your hinky volume dial..

cheers mate!
This volume control issue is one of the few common complaints in the Pro-197/GRE-600. The cause of the problem is apparently GRE's inexplicable decision to use a linear taper potentiometer for volume control as opposed to the preferred audio taper type pot:

Linear and Audio Taper:

The taper of a pot refers to the way its resistance changes as the shaft is rotated. A linear taper pot is exactly what you would guess it to be, a graph of resistance (from one end to center) versus shaft rotation would be a straight line. If you tried to use a linear taper pot as a volume control you would be most unhappy with its performance. The sound level would go from nothing to almost full volume in about the first ten degrees of rotation and the rest would have almost no audible effect. This is because the ear responds to sound logarithmically rather than linearly. That's why sound engineers use the decibel which is a logarithmic function of power. An audio taper pot has a function which approximates a logarithmic function.

The way to identify an audio taper pot is to set it to half rotation and measure from center to each end with an ohmmeter. If the resistances are approximately equal you have a linear pot. If the resistance from the counter clockwise end to center is about 10% of the total and the resistance from the clockwise end to the center is about 90% then you are holding an audio taper pot.

Source: http://www.angelfire.com/electronic/funwithtubes/Amp-Volume.html
 
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