Doesn't GB's testing methodology differ from other manufacturers when defining the output wattage of an amp? Static load testing vs. reactive load, or somesuch? And can/does this account for people's perception that the GB amps are "softer per watt" than other amps?
Edit: I'm thinking of the dust-up that followed Bass Gear Magazine's bench test of the GBE1200, but I didn't really follow that thread at the time, and it's Mega, so it'll take awhile to pick through it...
We use the area under the power curve method, because the output tube emulation limiter alters the waveform analogous to the way a tube power stage overdrives. This means that a standard meter (even a "true RMS") meter will not read correctly. True RMS is a math function conversion on most meters that applies only to pure sine waves. Any alteration of the shape of the waveform will result in an inccurate measurement. We also use a regulated 120 volt source (240 volts for export) so that numbers are repeatable regardless of AC power source.
There were numerous errors in measurement and methodology on the first set of reviews, we are all in agreement on this.
I have been working with Tom on how to corrolate power measurements across the various product types (including a more appropriate duty cycle based approach that does a better job of approximating dynamic power in the real world) and I hope to meet with them at NAMM to continue the progress. If we can make the tests practical to complete, I think it will help to make the test results more in line with real world experiences.
To expand a little on the power thing, my thoughts are that a continuous power number is pretty useless because a bass signal (like all music) is not a steady state signal. The FCC requires us to do all product testing at 1/8 rated power because that's pretty representative of a signal with 9dB(pwr) of dynamic range. I typically use between 1/4 and 1/3 power for all of my development testing (5-6dB) which is really at the most stringent end of heavily compressed signal. What is most important to the feel of an amp is how it handles the dynamics, and IF it has the potential to deliver higher dynamic power due to the power supply voltage, can it really deliver the goods with matching current delivery from both the power supply as well as the power amplifier. Unfortunately, this is a bit difficult (actually very difficult on the AP-1) to measure, though I am working on a mathamatical model that may give acceptable results. This is what I hope to discuss with Tom and his technical folks.
If this works out, it will give a more practical way to corrolate some numbers with how loud an amplifier sounds and just as importantly how it is likely to feel under dynamic signal such as bass guitar, in a much more simple, one or two number result.
Is this sort of thing of any interst to the readers of a magazine such as Tom's, or would it be too confusing?
