How many watts are you seeing, on the bench?

[Tone_Terrific]

Are Deluxes putting out 22W, sine wave at clipping, load resistor, meter, Vsquared/load? Classic 30's at 30W? JTM60 at 60?

Etc,. etc...are you getting rated or expected max power from most amps?
With the stock tubes, and how about with replacement tubes.....big variations?

[Ronsonic]

Generally, yes we see the rated power output. Often the rated output is not the same as the number in the Model Name. For example the GZW-100, might be a 72 watt amp according to the schematic.

But in general actual published power levels are for real, it's just the suggested or implied numbers you take with a grain of salt. And just because an amp has 4x6L6s doesn't mean it's a 100 watt amp.

There have been some power tubes that do not make rated power in some amps. The old Sovtek 5881 and variants produced lower power, especially in lower voltage amps.

For my testing, I use 3-400Hz, since that's where guitar music is, not the 1KHz that gives slightly bigger numbers. I test at the rated load and measure at the point of clipping or just before depending on the amp and application.

[torquil]

The Mesa Boogie Express 5:25 seems to have quite low output compared to its rated value. Check the second half of this thread:

http://www.grailtone.com/forum/viewtopic.php?f=30&t=42342&start=15

One guy in that thread (J.J) measured 1.3W in the 5W mode and 14W in the 25W mode...

I (tmac) measured around 2W in 5W mode. I didn't measure the 25W mode. All my measurements were for a 400Hz sine wave into 8ohm dummy load.

[RobRowland]

I'm sure the figures are quoted as 'nominal', but are manufacturers bound to any particular +/- when quoting watts?

[LowellH]

I'm surprised at how many amps measure spot-on their advertised output power. Deluxe Reverbs are usually 22-23W. Most classic Marshalls are conservatively rated - most 50 watters measure around 60W, 100 watters - 110-120W, at least in my experience.

I too measured an Express 5:25 about a week ago and got exactly 15W in hi-power mode. Can't remember what it made in low power mode but it was under 2W.

[Ronsonic]

Mesa are one of the companies that seem to not care much for power ratings. Them, I don't expect much power from relative to other amps with similar tubes.

[Roe]

generally, fenders put ut a little less than they are supposed to. marshall 50s a little less too. but the 100w tend to put out a little more

[Tone_Terrific]

Part2:
Do you find that if you vary the dummy load resistance, on some amps, you can pull greater wattage, or at least, closer to rated output?
I presume that it is possible to get closer to optimum power transfer even if off of nominal load value, under test conditions.
I just do enough of this stuff to keep myself confused.:bonk

[pdf64]

Old amps designed around the tubes available at that time don't put out the expected power levels with modern tubes. Eg late 70s/early 80s Fenders need STR387 Sylvanias, a Fender 75 will only put out about 60 watts with winged C 6L6GC.

[Ronsonic]

Part2:
Do you find that if you vary the dummy load resistance, on some amps, you can pull greater wattage, or at least, closer to rated output?
I presume that it is possible to get closer to optimum power transfer even if off of nominal load value, under test conditions.
I just do enough of this stuff to keep myself confused.:bonk

Don't do much testing like that unless there's an open question about the piece I'm working on. There's enough to get confused about already so mostly try to keep it simple.

[Roe]

Part2:
Do you find that if you vary the dummy load resistance, on some amps, you can pull greater wattage, or at least, closer to rated output?
I presume that it is possible to get closer to optimum power transfer even if off of nominal load value, under test conditions.
I just do enough of this stuff to keep myself confused.:bonk

yes a lower load can lead to more power and distortion. watch for redplating though

[phsyconoodler]

That's maximum output before distortion,right?I have a distortion meter to check that.
Funny,I find mesa amps to be above ratings.They are also louder than comparable models.

[JJman]

I'd like to know what people get from a 5e3 spec'd output. My homebrew uses a 5e3 output section and gets only 9watts clean.

[Jerry Glass]

Maybe I'm the odd man out here but I can't remember the last time a customer asked me to measure the output of thier amp.

[Ronsonic]

Since I'm going to run the amp up to full in testing anyway it takes little time to measure and add to the report. Customers seem to appreciate it. Especially if it's noteworthy. It's a useful test as far as general amp health and tube status.

[stump]

My Metro JMP50 puts out 51 clean watts and 85 watts at full volume.

[pdf64]

That's a bigger 'cranked/clean' ratio than I'd expect (usually 1.4 if tubes are clipping symmetrically) - how are you measuring it (true rms meter)?

[Roe]

My Metro JMP50 puts out 51 clean watts and 85 watts at full volume.

what's your tubes and plate voltage?

[Tone Meister]

I'm not a tech, but I remember just recently my tech telling me my EL34 Bogner Shiva with Winged C's was making well over 90 watts right at the point of clipping. The Shiva with EL34's is rated at 80 watts.

[stump]

what's your tubes and plate voltage?

Running Tesla EL34's(not JJ) at 460 Volts. My friend RussB did the measurement for me so I'm not sure of the specifics.

[TimmyP]

I find that most amps are about 15% low even on 120V to 125V mains. However I'm determining the onset of clipping by listening (via headphones tapped off of the dummy load) rather than on a scope, so I expect that on a scope I'd say the output is about to spec. Back in the 70s, using a scope (the same on I use today when needed), I got 95% to 105% of spec on the same load resistors.