Re: Marshall Speaker Reactance Emulator

Posted by traktop on Oct 11, 2016; 11:31pm
URL: http://guitar-fx-layouts.238.s1.nabble.com/Marshall-Speaker-Reactance-Emulator-tp31283p33469.html

induction wrote

Tabbycat wrote

... what do you use for your dummy load? is that a build of your own design or adaptation? a decent dummy load build is still on my list, but i feel fairly incapable of sorting crap designs from good ones, re the diy options out there. and destroying my amp would be too high a price to pay for experimentation along these lines.

My dummy load is very similar to the Weber Load Line with a slightly more sophisticated tone control. (SWTC V3, though after implementing my reactance emulator, I keep the tone control on the lineout flat anyway.) I'll post the schematic and layout here if you like. Except for the tone control, no vero is necessary, it's just a power resistor in parallel with volume pot and series resistor. The trick is that you have to build the dummy load circuit specifically to suit the amp you want to use it with. The power resistor has to be able to handle twice the output wattage of the amplifier, and the lineout voltage divider has to give the appropriate range of output voltages. My amp is a tiny (1-4 Watt Class A), so it was very simple. If you want a dummy load for a 100 Marshall, you'll probably spend one or two hundred clams on power resistors alone.

My DIY dummy load with 12" speaker impedance curve "emulation". It has 2x150w 8ohms power resistors in series for better heat disipation, so pretty much any 16ohms tap guitar tube amp should work here.
I use it as a resistive/inductive/capacitive atenuator for my 100w amp, (sometimes just as a paralell dummy load along with my cab). Planning on adding a line out to record with my audio card.