running a amp into a resistor (output loading)

[wakeguitar]

Hey, if anyone with experience can help me.

I want to run the rm100 with resistor in order to tap a speaker output signal whilst playing silently.

I bought a 100w 8ohm resistor, and wired it to the main speaker output. (the other output runs too a JDI).

I am still not sure what I should expect to happen, or if I'm doing damage to the power section or tubes.

I played like this, I noticed the amp (main volume knobs) were heating up more than usual, while the resistor was still room temperature.

Any info to share?

thanks

 

[mboogman]

For this to work safely, it's my understanding that you need an active, resistive load. Not sure exactly what that means, or what that is, but I'm pretty sure that's what you need.

 

[fishtank]

First of all, I would use a resistive load that is rated higher than the amplifier output - running one that is rated for only 100 watts with that amp is asking for trouble (I'd probably go double for extended use). Next, do you have the resistor mounted on a proper heat sink? There is quite a bit of power being dissipated into heat and it needs to go somewhere.

Now, if the resistor is not heating up and assuming the amp is not turned down, I'd say you have a problem. There should be plenty of heat generated.

FWIW - I would recommend picking up a THD Hotplate and using the line out to feed your JDI. The Hotplate has the proper load and proper heat sink to handle the amp and should be safer than what you are attempting.

 

[Julia]

Just buy a THD Hot Plate. That's what they're for. They have a line out.

 

[wakeguitar]

Ok thanks for the tips, I'm gonna look at Weber or THD to find something 'built' for the task.

My concerns is THD and some of the other have too many features I don't need (like multiple Ohm support, and actual attenuation which Randall's don't need), thus being too expensive for what I need.

I will try to investigate some variations as well, to try to find one that will offer a preferable sound as well as performance, it looks like Weber's custom builds these things.

cheers

 

[nomad100]

I used a 100W speaker motor sometimes and use the slave out to a dawn to practice and record. A resistor would work as well...

Like said above don't crank it with a resistor only rated for 100W. don't plug a DI directly into the speaker jack, or parallel with the speaker jack.

 

[Jerome Allen]

I've run various amps, including an RM100, into a Palmer PDI-03. The Palmer's one of the most useful pieces of gear I own. It's a passive load box/speaker simulator that can replace the speaker cab. It gives you an assortment of outputs to use live or for recording. It's rated at 100 watts and 8 ohms. It does get hot, like all resistors do. But I've had no problems at all with it handling an RM100 with Master up between 50-70%.

 

[wakeguitar]

In the end I got one Hoelectronics custom http://hoelectronics.com/. Perfect and sounds good too, for $100. Just a dummy load and a line out with a volume control.

very happy to use this instead of just send jacks which I was using before.

thx for all the advice.