Tell me why this won't work...

[plumcrazyfx]

https://www.harborfreight.com/router-speed-control-43060.html

I'm dumb enough to try it.  It says 15A.  I was thinking it looked like it could be similar to a VVR, but external.  Tell me why I'm a moron.

[sluckey]

Bahahaha!

[plumcrazyfx]

Okay, at least tell me how I'm being an idiot.  Looks to be using a Triac.

[sluckey]

It's only 20 bux. Get it and give us a report.

[NewYorker]

My assumption is that it operates like your basic light-dimmer, i.e. by turning the AC waveform on and off at varying points in the + and - swings of the waveform.  (Triac's do this.)  A light bulbs will see this as varying levels of energy coming in with each waveform, and thus varying levels of power, in effect.  The light build averages this out and thus gets brighter or dimmer.

A guitar amp, on the other hand ...  isn't a light bulb.

Somebody with a better understanding of the engineering principles at work here can explain in more detail.

My guess is that this control would, at best, introduce a lot of noise into the amp, or, at worst, do something really bad.

If I were to try this, I'd start at the FULL setting and then back down slowly.  The first indication of trouble may be that the amp starts to hum or buzz, because the rectified voltage doesn't stay high enough, long enough, on each cycle to keep the filter cap's charged.

Ed

[JayCobie]

There are plenty of gut shots of this thing on the googles if you search for "Harbor freight speed control".
It uses a triac.

Here is an instructable mod guide that has plenty of shots of the guts:
http://www.instructables.com/id/Harbor-Freight-Router-Speed-Control-Mod/

[Willabe]

Anything that drops the voltage to the power transformer primary will drop the voltage on ALL the secondaries. 

That would drop the heater voltages, if their on the same power transformer.

A VVR/Power Scaling only drops the B+ and some track the -bias dcv too.

Tubes don't work well or at all with out the correct heater voltages, +/- 10%.

 

[plumcrazyfx]

A bucking transfomer lowers everything.  Just using it while roastibg coffee so it got me thinking.  Usually causes problems.

[jjasilli]

Back to the AC motor speed control:  https://electronics.stackexchange.com/questions/244591/can-i-run-audio-signals-through-a-dimmer-switch-to-control-volume


I use one of these; works for me:  https://www.parts-express.com/cat/speaker-l-pads/306

[sluckey]

I usually take my really stupid questions straight to google. Usually get a good answer in just a few minutes. That way I don't have to listen to a ration of shit from real crazies like me!