ED output power

[J.J]

Ok guys, I have been meaning to put this out for a while.

Whenever I get a new amp I measure its output power, mostly just out of curiosity.

My amp was two weeks old when I did the test, so the tubes were very fresh. The test was done with an 8 Ohm load. I should do the test agian with a 4 Ohm load to see there is any change.

Here is what I found with the ED.

45 watt mode:

18 watts RMS before clipping.
28 watts RMS heavily clipping.

90 watt mode:

67 watts RMS before clipping.
98 watts RMS heavily clipping.

I don't know how Mesa do the ratings on their amps, but you can see that 45 watt mode is quite a bit down on power compared to its rating. The differnce between 28 watts and 45 watts is only about 2 dB so for anyone worried, you would only just notice a difference in reality. Personally I like the lower power in 45 watt mode as I can get the amp singing more easily. My Express 5:25 only manages 2 watts from its 5 watts mode.

 

[Assumer]

amazing how loud 18 watts can be.

 

[>Photi G<]

It has to do with the bias. The resistors installed at the factory set a rather high [relative] voltage. Last I checked, Simul-Class amps had a supply of -57 to -61 volts, which leads to a cold bias, around 34mA for 6L6GC's, or only about 45% plate dissipation. That's why it is measured that low. Now if you swapped resistors, and brought the bias up to 43mA, you'd hit about 70% dissipation, which would be about 160W peak. These numbers are off the top of my head, so don't quote me. :mrgreen:

 

[YellowJacket]

amazing how loud 18 watts can be.

With how efficient guitar speakers are, even one watt is surprisingly loud. The ED also has a huge amount of horsepower given what the numbers say should be happening. I'm sure 18watts of Electra Dyne fury through a 4 x 12 would utterly annihilate a 1000watt home theater system with a sub. I get the impression the Electra Dyne is a particularly loud amp, as far as amps go.

 

[J.J]

Yes 18 watts can be very loud. A V30 speaker running at 18 watts would make 110dB one meter from the cone.

A typical home theater speaker would need 10 times that power, or 180 watts RMS to get the same volume just due to the lower speaker efficiency. Those cheap 1000 watt systems probably in reality don't even total 180 WRMS across 5 speaker and the sub.

The 18 watt figure is just before clipping, so that is really the clean headroom. It will still get louder as it gets into it's breakup.