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Watts; the worst measurement unit ever for amp output?

N

nukes_da_bass

Inactive
Feb 19, 2006
2,220
1,967
west suburban boston
#1
I currently own two amplifier heads; The first one is an Eden WTX 264. The other is a Mesa boogie 400+.
Both of these heads are rated at extremely similar power output into 4 ohms. Between 264 and 275 W.

Using the same cabinet, a Schroeder BMF 212, the Eden's maxed out i.e. will begin to distort unpleasantly with all my knobs at about 2 oclock with the bass boost pulled out and the mid shift pulled, utilizing every single bell and whistle, I can barely play bass in my band to a medium-size room.

With the Mesa boogie into the same 4 ohm cabinet, master at three volume three I never ever ever can crank the controls on the same bass past halfway and I'm already too loud for the same room!

Watts mean nothing!! The first statistic an amp manufacturer should list is DB at 10 meters, 50 meters, 100 meters with minimum acceptable harmonic distortion.
What I'm trying to say is...I don't care what the power output wattage rating of any given amplifier is, before I plug it in to a known cabinet and get a chance to tweak the settings of the amplifier and see what it's actually capable of, that wattage measurement means nothing to a practical working musician. At best, watts are an indicator of what not to plug into an underrated cabinet so one doesn't blow it up.
Thoughts?
 
#4
Pilgrim said:
It sounds to me like you just haven't found the right settings on the Eden.

Try the same thing with no bass boost and the knobs set as close to neutral as possible.

Many amps have very different treatments of such things as "bass boost".
Click to expand...

Tried it- bass boost off, master cranked, gain at 10 oclock (anything under 10 oclock sounds anemic with this amp and cab combo).
Id hand you a $50 bill if you could get the WTX 264 to put out 75% of the punch the 400+ does at well under half max output!
I feel like you're about to tell me "a watt is a watt" which is exactly the point I'm making in this thread... watts are auseless measurement for bass amplification for real life working musician.
 
#6
I think the OP means "maximal" rather than "minimum" in the statement "The first statistic an amp manufacturer should list is DB at 10 meters, 50 meters, 100 meters with minimum acceptable harmonic distortion," since most people would be likely to prefer as low a harmonic distortion number as possible.

That said, as long as the amp manufacturers specified the speaker cabinet used to measure the dB levels, this sounds like an excellent suggestion.
 
#7
You also have no idea of how the maker sets the controls. Just the taper of the volume pot can make a huge difference in the output at the same knob position. When we design consumer products, we always design in the ability to over-drive the control a little bit, so the buyer feels he is getting his money's worth.

ALSO - The Wattage rating needs to be at a specific % THD to be able to compare apples to apples. We produce many plate amps for powered speakers. Our power ratings are at 1% THD. Other manufacturers rate theirs at 10%, so it appears that theirs has more power.

Said distortion can also make an amp seem louder as it adds more harmonics to the signal.

In addition, adding boost or cut via the tone controls can also greatly change the gain, and again, the result at the same knob position is totally inconsistent from one brand to another. The tone control could have 6 dB of boost or 20 dB. The pot curve could be totally different.

Finally, the difference in SPL created by different amounts of power are inaudible until there is at least a 2:1 difference, and it takes 10X the amp power to create twice the sound output from the speakers. Amp power and SPL do not increase the same. Amp power increases as the square of the voltage and SPL increases as the CUBE of the power. That is why it is always better to add speakers to increase your level - just FYI.
 
#8
A Watt is a Watt but an amp is not an amp.

That is, companies will rate amp specs differently. Some are known for under rating their amps power output. So when compared to another product of equal published specs, theirs will sound louder.

Also, volume pots have different specs. They are usually log pots meaning that they follow a log curve as you turn the pot. Pots are not all alike, they have different log curves. What this means is that on one pot you could be at full volume at a very low setting relative to another pot. That amp is going to sound louder at a lower volume. This is a marketing thing.
 
#11
beans-on-toast said:
Bassamatic types faster than I do and made similar points. :p

It is hard to know when you on a level playing field when comparing amps. Test equipment can help you see what is really going on.
Click to expand...

"Watts; the worst measurement unit ever for amp output?"

No. It is a great measurement.

"Watt" is a unit of measure - and defined as Volts times Amps. A Volt is a Volt, and an Amp is an Amp - that can't change, and since it can't change it is locked down and solid.

It would be practical, informative, and easy on the consumer, if they all published specs with everything equal, like SPL data when using the same cab, but that won't happen. Who gets to make the golden cab that everyone tests with?

Beans and Bassamatic are right on about ratings.

Amplifier manufacturer have been making a money for years by the confusion created by different measurement techniques. That is not just for musical instruments, but stereos too.
 
#12
Not being a tech, this all seems about right, or wrong
depending on how you want to look at it.

What about speaker power rating?

The guys that made the early JBL speakers estimated
their power handling capabilities by just turning them
up until they distorted and estimating how much that
was.

I'm sure the Eden WTX 264 and Mesa boogie 400+
don't sound equal.

I've got another one for you;

The Fender Rumble 350 head is rated at 350 watts
at 4 ohm. The Gallien Krueger 400RB-III is rated at
240 watts at 4 ohm.

Put them side by side using the same cab/cabs, it is
a wash, and GK sounds bolder.

That's a total difference of 110 watts and it seems
insignificant,

Tabdog
 
#13
tabdog said:
Not being a tech, this all seems about right, or wrong
depending on how you want to look at it.

What about speaker power rating?

The guys that made the early JBL speakers estimated
their power handling capabilities by just turning them
up until they distorted and estimating how much that
was.

I'm sure the Eden WTX 264 and Mesa boogie 400+
don't sound equal.

I've got another one for you;

The Fender Rumble 350 head is rated at 350 watts
at 4 ohm. The Gallien Krueger 400RB-III is rated at
240 watts at 4 ohm.

Put them side by side using the same cab/cabs, it is
a wash, and GK sounds bolder.

That's a total difference of 110 watts and it seems
insignificant,

Tabdog
Click to expand...

BOlder is a very good way to put that, tabdog! I have played both of the amps you speak of and I agree… The GK sounds bolder than the fender rumble 350 which in my opinion over distorts far too early.
 
#14
nukes_da_bass said:
I currently own two amplifier heads; The first one is an Eden WTX 264. The other is a Mesa boogie 400+.
Both of these heads are rated at extremely similar power output into 4 ohms. Between 264 and 275 W.

Using the same cabinet, a Schroeder BMF 212, the Eden's maxed out i.e. will begin to distort unpleasantly with all my knobs at about 2 oclock with the bass boost pulled out and the mid shift pulled, utilizing every single bell and whistle, I can barely play bass in my band to a medium-size room.

With the Mesa boogie into the same 4 ohm cabinet, master at three volume three I never ever ever can crank the controls on the same bass past halfway and I'm already too loud for the same room!

Watts mean nothing!! The first statistic an amp manufacturer should list is DB at 10 meters, 50 meters, 100 meters with minimum acceptable harmonic distortion.
What I'm trying to say is...I don't care what the power output wattage rating of any given amplifier is, before I plug it in to a known cabinet and get a chance to tweak the settings of the amplifier and see what it's actually capable of, that wattage measurement means nothing to a practical working musician. At best, watts are an indicator of what not to plug into an underrated cabinet so one doesn't blow it up.
Thoughts?
Click to expand...

I and some friends once compared a Honda Civic to a VW jetta. We felt that the Jetta with less horsepower felt faster than the Civic. There are a lot of variables that could account for this. The Jetta has more torque, the gearing is different, the weight of the vehicles are different, the power curve on the Jetta is at a lower RPM than the Civic, Hondas love to be reved high, not to mention that VW and Honda uses different methods of rating and testing their engines. Now this has nothing to do with bass amps, but I think maybe its relavent.
 
#15
nukes_da_bass said:
Tried it- bass boost off, master cranked, gain at 10 oclock (anything under 10 oclock sounds anemic with this amp and cab combo).

Id hand you a $50 bill if you could get the WTX 264 to put out 75% of the punch the 400+ does at well under half max output!
Click to expand...

Dang.

nukes_da_bass said:
I feel like you're about to tell me "a watt is a watt" which is exactly the point I'm making in this thread... watts are auseless measurement for bass amplification for real life working musician.
Click to expand...

That's not my implication at all. I'm simply thinking that there must be another factor (or more than one) causing the difference in sound. It could be a number of things, including an amp malfunction.

Watts do matter, but I agree with the spirit of your post in that I understand Brand A claiming 300W vs. Brand B claiming 300W can result in two very different kinds of performance.

That doesn't mean wattage is irrelevant; one has to have some measures by which we can at least place equipment in different categories.

Electrical devices are measured in very different ways, and it's normal for each manufacturer to manipulate their specs in such a way as to make their equipment look as good as possible. That's true for cabs as much as for amps, so of course both matter.

I guess you can sum it up with the old cliche: Figures don't lie, but liars figure.

I suggest that we can think of it a bit like horsepower in car engines. 300 HP in 1965 was measured a very different way than 300 HP is measured today. And 300 HP through a differential of 4.10 gears results in drastically different acceleration and gas mileage than 300 HP running through a differential with 2:10 ratio.

That doesn't mean HP is irrelevant - but you need to know the rest of the story about how that HP is applied. Kind of like wattage ratings. Like most things in life, they're not as simple as we'd like.
 
#16
I started this thread for a reason… I don't disclaim the science at all, in fact I am the son of an electronic engineer. I don't have his engineering abilities, but I don't negate the science involved. It's the presence and the attack of the amplifier that is in question, SPLs and DB not being equal from 300 watt amp to 300 watt amp for the most part.
I feel bad for newbies that think that a certain wattage output rating is going to get them a certain DB volume level equally from amplifier to amplifier into the same 4 ohm cab.
 
#17
The real measurement for an amplifier is voltage swing at whatever level of distortion. That then gets calculated to various amounts of watts depending on the impedance of the load.

The voltage measurement results in smaller numbers though, so they don't look nearly as impressive. ;)
 
#19
One way to standardize output power ratings, (which will never happen), would be for manufacturers to agree on a "Standard Speaker", (which would be comprised of a driver, and cabinet system), measured in a "Standard Room", while operating under some standard of defined maximum distortion when operated by a defined standard input signal, as measured by an agreed upon standard measurement method. If a group such as ISO administered such a system, manufacturers would still try every trick they could think of to give them some advantage in the minds of consumers.

Best thing to do, is consider that a reputable manufacturers claims of power ratings will put any particular amp, or speaker in a "class" of similarly rated equipment, and assume actual performance will fall within a range.

It is more like an estimate. There are too many (valid) ways to make a technically accurate statement about some physical parameter that can be measured in the lab, yet which does not translate into actual real world amplification of a complex electrical signal of a musical instrument, (that will end up in any (typical?) human brain by way of any (typical?) human ear).

If we all wanted to use our amps, and speakers to listen to pure sine waves, we could probably define a standard that would be more able to compare one system to another.

I expect my 500 Watt amp to be louder than my 25 Watt amp. That's a good enough practical concept for me to know what to expect from each amp. I don't really care if my 500 Watt amp would be measured to be putting out 450, or 550 Watts.
 

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