Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on June 11, 2011, 09:57:02 am
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Has anyone tried to replace volume pot with a 12-position switch?
I think there could be some beneficial things e.g. regarding conduct.
/Leevi
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Some fancy Hi-Fi stuff does things like that. Even more than 12 position.
On the same lines... I got a request to install a volume pot that only goes to 4.
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Just get a multi-position single pole switch and connect the several resistors in series. I've seen a chart on the web somewhere for selecting the resistors so that it is still audio taper. Also there are volume pots with multiple detents that feel like a switch.The switch needs to be of the "shorting" (make before break) type to avoid pops and clicks.
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Usually that way is taken by HiFi guys
a "more than 24 position" rotary switch is often chosen for that application
Kagliostro
p.s.: I don't know if the game worth the candle, we are talking about a guitar amp, no HiFi
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Usually that way is taken by HiFi guys
Yes, that's true
Anyway a pot is a very important component in the guitar amp as well i.e. the signal goes through the pot.
Furthermore the quality of the pots varies depending on the brand and age. I think a switch would have
a more stable and lasting quality.
/Leevi
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There are high-end pots available. Some are sealed to keep dust out.
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I've just find (casually) this
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140560922408+&clk_rvr_id=239754792214 (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140560922408+&clk_rvr_id=239754792214)
I must say that I find those attenuators VERY nice
Kagliostro
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Just curious, what are the draw backs to using a pot. Seems like using a switch you'd lose the ability to fine tune. Isn't a pot really a switch with infinate settings? Why limit yourself to 12 or 24 volume "settings"?
Is this wired in a way that not on varies the voltage divider but also changes the total value?
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Is this wired in a way that not on varies the voltage divider but also changes the total value?
you know english isn't my language
can you put the question in an other way ?
about the choice for an attenuator instead than for a pot I think the principal reason is that this kind of solution give a constant response in the time because there isn't any aging of the resistor surface as in a pot
Kagliostro
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Just curious, what are the draw backs to using a pot.
I hope the picture tells that:
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Just curious, what are the draw backs to using a pot. Seems like using a switch you'd lose the ability to fine tune. Isn't a pot really a switch with infinate settings? Why limit yourself to 12 or 24 volume "settings"?
True - for audio pots that are really smoothly tapered. Most off-the-shelf 'audio' pots are simple '2-line taper' pots which have a one linear taper for the first part of the turn, and a second linear taper for the second part of the turn*. In this context a 'switching' attentuator with bazillions of settings could give a fairly infinitesimally smooth taper which would be a better taper than a 2-line taper 'audio' pot. But what a hassle to make? Of course you could buy one instead (but in a geetar amp, why fork out?). In a geetar amp, most peeps wouldn't be able to tell the difference between a fancy attenuator and a 2-line taper 'audio' pot.
On the other hand a linear pot would be 'superior' to a linear tapered attenuator in all respects (where you use a linear pot).
* You can make a better audio taper pot using a linear pot and a tapering resistor and a bypass cap.