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Anyone build an amp load box

Started by BryGuy, January 12, 2018, 01:49:57 AM

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BryGuy

Friend of mine asked me if I could build an amp load box for his amp. He basically wants to run the amp silent and just use the direct out. So anyone have any advice or a goby designs/schematic? Can it be as simple as a resistor in a box? I guess the biggest concern is getting rid of the heat. He says it's a 15 watt amp but I should know more when he sends me all of his gear info.

gordo

It can be, but the results are sometimes under-whelming.  I have a simple resistance load box that's switchable for 4/8/16 so I can bias tube amps without blowing out a speaker.  I also have load resistors built into most of my "public" amps I leave at church so that if someone fires it up without plugging in a speaker cab it won't smoke an OT.

If looking for recordable line out it's hard to beat the Weber/THD/Riviera boxes but they're pretty pricey and in that order.
Gordy Power
How loud is too loud?  What?

flanagan0718

I'm building one for a friend (hopefully) this weekend. The resistors are kind of pricey. I got 4 ohm 50 watt resistors. He has a 30 watt head so 50 will be more than enough. I'm putting a 4 / 8 / 16 ohm selector switch in it so he can use it for other heads too (50 watt max). I'm also going to see if i can get an output volume control for his headphones.

gtr2

I have a weber mini mass that wasn't too much more than what it would have cost to make it.  It has a reactive load.
It works great but if you want to use the line out you'll need some sort of speaker sim to run it through.

Josh
1776 EFFECTS STORE     
Contract PCB designer

HamSandwich

#4
Quote from: gtr2 on January 12, 2018, 04:07:43 PM
I have a weber mini mass that wasn't too much more than what it would have cost to make it.  It has a reactive load.
It works great but if you want to use the line out you'll need some sort of speaker sim to run it through.

Josh

I have their mass lite, 100W. Highest wattage amp I used it for was a JTM45, which has varying wattage estimates, but certainly not over 50W. I can run it silent into cab sims on a computer with really great results. I've read you're supposed to shoot for 2x the wattage if you're going to turn the amp down to silent, FWIW.

OTOH, I have tried a resistance based load and while I'm sure you can find a sound in there with enough processing afterwards, the Weber product blows it out of the water (based on my amazing and unbiased memory  :P :P :P :P :P )

I believe it was FSB that had schematics of the Weber load boxes. Quick search has this one with the reactive loads on the front page, might have to search a little deeper for the resistor ones,  but I'm sure I've seen them on there somewhere.

http://www.freestompboxes.org/viewtopic.php?f=2&t=2287