Members elsupermanny14 Posted July 17, 2008 Members Share Posted July 17, 2008 Bear with me as I try to explain my question (sorry). Ok I'm curious as to how an attenuator decreases the output of an amp. For example let's say I had a 20watt amp with no attenuator. I would be cranking out 20watts, duh... Ok no let's say that I put an attenuator on it to lower the output. If I turned down the attenuator to half power would the amp decrease its wattage to 10watts which is half of 20watts numerically, or would it decrease its power output but a half? So if the amp had 20watts of power would the attenuator bring it down to 2watts of power, which is exactly 50% output at 20wattts? Sorry if my question is a little unclear, but if anyone could please help me out that would answer a lot of my questions! Thanks guys! Link to comment Share on other sites More sharing options...
Members Wyatt Posted July 17, 2008 Members Share Posted July 17, 2008 It's rare to never that attenuators are mathmatically exact in their numbering, it's all about how they are designed. Often it's a n amount of attenuation as measured in decibels (for examble see the Dr.z one and others say -3db, -6db, etc.), and often they are logarithmic offering a lot more nuance when attenuation is minimal and creating much broader changes when using a lot of attenuation, because at that point the tone is altered significantly anyway. Just know that as you turn up the attenuation, the more of the amp's output is run through a resistor or speaker dummy load to be absorbed and dissipated before it reaches the speaker (wattage is merely a measurement of heat dissipation). How much attenuation is enough is all dialed in by hear. A 20-watt tube amp (because a SS amp needs no attenuator) is 20 watts RMS. That means at maximum *CLEAN* output, the amp is consistently putting out 20 watts. Once you start to overdrive the power amp, you beginning peaking far above that RMS rating. So a 20-watt tube amp can peak at over 30 watts. Link to comment Share on other sites More sharing options...
Members guitarcapo Posted July 17, 2008 Members Share Posted July 17, 2008 "power" is rated in watts"volume" is rated in decibels So I would assume the power would be reduced to 10 watts if it was initially putting out 20 I was under the impression that the way an attenuator worked was by absorbing some of the output of the amp, shunting it away from the speaker. In theory you could just wire a bunch of resistors in series and in parallel to your speaker to offer up resistance and convert the power to heat instead of moving the speaker. The problem is that resistors don't react to the amp's output dynamically like other speakers would and the sound coming out your speaker doesn't sound as good. The perfect solution would be to convert your amp to a 4x12 and run 3 of the speakers into a closet somewhere where they couldn't be heard. The one speaker left would be putting out 1/4 of the sound when the amp was cranked so you get the cranked sound at lower volume. Attenuators are the more practical solution. They act more like an actual speaker load to the amp. This is different than a master volume situation in that the power tubes and output transformer are moving the speaker as designed. You get a more realistic cranked amp sound at lower volume. Somebody correct me if I explained it wrong. Link to comment Share on other sites More sharing options...
Members ~Abstract~ Posted July 17, 2008 Members Share Posted July 17, 2008 In technical terms... It takes power in. It feeds a small portion to the speaker. It feeds the other part to a large resistor...which turns the sound into heat. Link to comment Share on other sites More sharing options...
Members Runn3r Posted July 17, 2008 Members Share Posted July 17, 2008 http://en.wikipedia.org/wiki/Attenuator_(electronics) http://www.amptone.com/powerattenuatorfaq.htm Link to comment Share on other sites More sharing options...
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