Speaker Dummy Load Question

[Gage2k5]

Hi,

I want to connect a dummy load to the output of my Crate GTR80DSP amp so that I can safely disconnect the speaker. Power will be kept at very low levels. I thought I could connect an 8 ohm 80w WW resistor in place of the speaker. I know dc resistance is different than impedence, but they are pretty close for my purposes. I probably will go to a 10 or 12 ohm just to be safe.

The amp is a hybrid, and I do not have a schematic, but I do have a block diagram that shows a tube ( I think a 12ax7 or 12au7)) along with a mosfet in the output section.

I also thought of using another speaker and cutting the cone out and using it it in place of the amp speaker to act as a load.

What do you all think?

[cbarrow7625]

Is the output solid state? If so you don't need to attach any dummy load, you can really just unplug the speaker (unless you need an 80W heater because you're cold or something). Tubes need to have a dummy load on them to reflect back the proper impedance through the transformer so that the output tubes are working into the proper impedance. If there is no load & the power tubes are working into a high impedance they will die premature deaths. Solid state amps don't care. They make a constant voltage output regardless of the load attached (or lack thereof) down to their rated impedance limits.

Don't cut the cone out of a speaker. That will not work very well. Once you cut the cone out all you have is 8 ohms of very light wire that will no longer move back & forth in the gap the way it is meant to. It will just burn up over time.

Chris

[Gage2k5]

Hi Chris,

I found the answer in another thread in this forum about dummy loads. The answer is a wire wound resister will work.

Thank you for your reply,

Lon

[Enzo]

Actually, you found the answer here too. Your amp has a solid state power amp, and they DO NOT require a load. A dummy load is a waste of your money here. Only tube power amps MUST have a load.

[Gage2k5]

You are right, but I had to make sure. The tube in the final is a driver for the Mosfet.

Thanks for your response.