Watts manufacturers doings to us - RMS vs Peak - it’s time to take a stand

[Cuzzie]

But they boast about who has the longest wanger 

[Lozz196]

On ‎16‎/‎11‎/‎2018 at 19:31, Bill Fitzmaurice said:

Google : 'Gain Staging'. The gain of the pre-amp and how the gain and/or volume controls are configured define how loud an amp will be at given knob settings. It doesn't affect actual output capacity. There are amps that produce full power with the knobs set at 3 or 4, but they don't produce any more power at higher settings. There are amps that are quite linear from zero to 10. In the case of the former some companies did so intentionally so in a music store their amp would be much louder at 3 or 4 than the one next to it, confident that they wouldn't be compared with both set at 8 or more, lest the store owner pull the plug. 

This is what was explained to me when I was at Ashdown, they said that they have their volume controls so that they go louder the whole way round, rather than peaking at 3 or 4. 

[ebozzz]

4 hours ago, Phil Starr said:

OK then that explains perhaps why you have concerns and why those of us who have dealt with these issues over a number of years are so frustrated with you. It's a simple matter of misunderstanding.

Measuring an amplifier's output is basically very simple. You connect it to a big resistor of 4ohms (say) put a signal into it and increase the signal until it starts to distort. At that point you measure the voltage the amp can do without distortion (less than 1% is the usual measure) and then the power is voltage squared divided by the resistance. Conventionally this is measured over the whole range of our hearing 20-20,000Hz. It's slightly more complex for a class D amplifier as this operates on high frequency pulses all at the same voltage but passing it through a low pass filter makes comparable measurement possible.

In the US there is long standing Federal legislation to stop misleading claims by advertisers and in Europe various standards exist with the DIN standard widely known. https://en.wikipedia.org/wiki/Audio_power There's some good links at the bottom of the article if you are interested.

You simply cannot design an amplifier without knowing all of the parameters and indeed specifying all the parameters of you amps so the claim of 'we don't know the rms power' or 'we don't calculate it that way' isn't credible.

Another factor is the input power, an amp cannot put more power into the speaker than it takes from the mains. In fact it will lose power both in it's power supply and in the amplifier itself. A class D design with a switch mode power supply is likely to be somewhere in the 80% efficiency range, so if the amplifier has indeed an input rating of 880W then it can only put out 700W. Then there is the long history of Behringer over claiming power outputs in their advertising. For example I own an old Behringer EP2400 PA amp, claimed output 2400W. When you delve into the manual as I did before I bought the amp I found it would produce 285W continuous into 8ohms with both channels driven. I was using 300W speakers at the time so it was an ideal match and a lot of bang for the buck so a good buy. The over -claiming was irritating but I'm a scientist and the data was all available. With the Beyron it isn't and Behringer are no longer publishing all the data on a lot of their gear. I think it's pretty stupid really as a 500W amp at this price is still beating the whole market and false advertising just makes the company look suspect and contemptuous of their customers.

As a 'Physics person' I come on here to repay all those who have helped me with my bass playing by advising them as best I can on technical stuff. I'm still enough of an old hippy to see the people here as friends and I don't want them conned. If someone delivered a Beyron to me it wouldn't be difficult to test it but I know more than enough to know that it makes way less than 2000W. If it is part of the decision of what to buy then I want people here to know what is true and what is incredible.

Thanks for this explanation. It's been the one most helpful to me on this thread or other. No sarcasm here. I'm going to ask you a direct question. As frustrating as you and others seem to think I am, I'm really not trying to be that. 

Bugera claims that the amp is 2000 watts peak at 4 ohms. You feel that it's not near that value. Could you please elaborate on why you feel so strongly that it's not? 

[ebozzz]

49 minutes ago, Lozz196 said:

This is what was explained to me when I was at Ashdown, they said that they have their volume controls so that they go louder the whole way round, rather than peaking at 3 or 4. 

I love Ashdown amps. With my Rootmaster 800 EVO without using the compressor, the gain stage is pretty smooth. With the compressor engaged? It gets a lot louder much earlier than either of my other two amps. 

[ianrendall]

I like to compare peak amp output to the Bugatti Veyron; yes, it WILL reach its claimed maximum speed of 253mph, but will only last 5 mins until the tank runs dry. I’d like to see amp manufacturers perhaps use - back to the motoring analogy - a sustainable cruising speed rating.

[Bridgehouse]

24 minutes ago, ianrendall said:

I like to compare peak amp output to the Bugatti Veyron; yes, it WILL reach its claimed maximum speed of 253mph, but will only last 5 mins until the tank runs dry. I’d like to see amp manufacturers perhaps use - back to the motoring analogy - a sustainable cruising speed rating.

Which is kinda what RMS is supposed to do...

[ianrendall]

8 minutes ago, Bridgehouse said:

Which is kinda what RMS is supposed to do...

I know. I was just desperate to get that anology in somewhere!

[Bridgehouse]

4 minutes ago, ianrendall said:

I know. I was just desperate to get that anology in somewhere!

Lol. My bad 

[itu]

1 hour ago, ebozzz said:

Bugera claims that the amp is 2000 watts peak at 4 ohms. You feel that it's not near that value. Could you please elaborate on why you feel so strongly that it's not? 

One thing is this power taken from the mains. If the unit takes less than claimed, the unit should be able to produce this amount of extra power by itself. Got it? It should be able to create power from, yes, where from?

Another thing is "peak" and its many forms. It may be possible, that this claimed peak power level is just calculated optimum output in milliseconds scale to some theoretical 4 ohm load - in theory. It does not exist in real life but it is nice to tell people incredible numbers, because there may be people who believe that you can get that much out of it.

Does this serve us customers? I don't think so.

[Phil Starr]

8 minutes ago, ebozzz said:

Thanks for this explanation. It's been the one most helpful to me on this thread or other. No sarcasm here. I'm going to ask you a direct question. As frustrating as you and others seem to think I am, I'm really not trying to be that. 

Bugera claims that the amp is 2000 watts peak at 4 ohms. You feel that it's not near that value. Could you please elaborate on why you feel so strongly that it's not? 

Fair enough.

If we assume the Bugera is a well designed class D amp with an efficient power supply and draws 880W from the mains and can run continuously at that level then it is probably around 80% efficiency and can supply about 704W. That's with an undistorted sinewave within the passband of the amp. That's the value of what is normally described as the RMS or continuous value. If you look at section 3.2 of the Wikipedia article then you see the peak power of a sine wave is twice the average power. So if it is a 704W amplifier than the peak power is 1408W. If you look at a range of amp and speaker specs you'll see that there's a fairly consistent description of things described as 500W continuous 1000W peak, 200Wrms 400W peak and so on. It's a simple mathematical ratio which enables those who want to boast that their system is 1000W but allows for fair comparison. Actually it is meaningless as it is always double so no extra information is being given. If any other figure is given then as the Wiki article says about PMPO there is no accepted way of calculating the figure and it is without merit. Basically the sums don't add up.

you can see my disquiet if you look at the advertising, here for example https://www.gear4music.com/Guitar-and-Bass/Bugera-Veyron-BV1001M-2000W-Bass-Amp-Head/1WNV

lot's of mentions of 2000W no mentions of peak power here, I suspect both Gear4music and Music Group know people will choose this amp on the basis of the 2000W and it looks a lot better than the Little Mark 3 https://www.andertons.co.uk/bass-dept/bass-amps/bass-amp-heads/solid-state-bass-amp-heads/markbass-little-mark-iii-bass-head 

In practice I suspect they would produce very similar power levels. Even if the Veyron is 700W and the LM3 is 500w that difference will only barely be audible. Sensibly you'd decide on tone (I hope!) reliability, after sales and price rather than power but for someone with no technical ability that 2000W looks so tempting. If we accept this then Markbass would eventually be forced first of all to sell their amps at peak power of 1000W and then start making up figures to compete. I think it's a better world where honesty is rewarded and we ask for proper measured ratings which can be compared fairly.

 

[Bridgehouse]

Hang on.. so Peak Power is double (approx) RMS. so that means that Bugera are effectively stating 1000w RMS. 

Furthermore they are stating 880w consumption - so the amp is, on average more than 110% efficient on average??

Where is this magic box creating the extra power from?!

[Bill Fitzmaurice]

PIxie dust.

 

[Passinwind]

On 16/11/2018 at 01:40, itu said:

By the way, went to see this "kilowatt amp". Its backplate clearly states, that the unit's input power is 200 W and 200 watts only! How could they explain this kilowatt if not using the word "peak"? Funny stuff.

https://www.trickfishamps.com/amplifiers/bullhead-1k/

In the US the unit's power consumption from the wall  figure is typically spec'ed at 1/8th duty cycle, although 1/4-1/3 is generally more realistic for rock or hard rock with some signal compression. You can easily confirm the relevance of this by recording some actual bass guitar playing and analyzing the crest factor.

[Jus Lukin]

-

Edited March 1, 2022 by Jus Lukin

[PaulWarning]

2 minutes ago, Jus Lukin said:

They aren't! It's just a fun thing people like to say on the internet. I have a real soft spot for Trace Elliot, but that 'Trace Watts' thing is nonsense.

think the Trace Elliot watts thing is a bit tongue in cheek, what it means is that Trace Elliot are very conservative in their ratings, and I suspect the volume control reaches maximum output way before 10, I don't know because I daren't turn mine up past 4, now if they took a leaf out of Bugera's book they rate their amps at a million watts peak 

[dyerseve]

17 hours ago, Phil Starr said:

Fair enough.

If we assume the Bugera is a well designed class D amp with an efficient power supply and draws 880W from the mains and can run continuously at that level then it is probably around 80% efficiency and can supply about 704W. That's with an undistorted sinewave within the passband of the amp. That's the value of what is normally described as the RMS or continuous value. If you look at section 3.2 of the Wikipedia article then you see the peak power of a sine wave is twice the average power. So if it is a 704W amplifier than the peak power is 1408W. If you look at a range of amp and speaker specs you'll see that there's a fairly consistent description of things described as 500W continuous 1000W peak, 200Wrms 400W peak and so on. It's a simple mathematical ratio which enables those who want to boast that their system is 1000W but allows for fair comparison. Actually it is meaningless as it is always double so no extra information is being given. If any other figure is given then as the Wiki article says about PMPO there is no accepted way of calculating the figure and it is without merit. Basically the sums don't add up.

you can see my disquiet if you look at the advertising, here for example https://www.gear4music.com/Guitar-and-Bass/Bugera-Veyron-BV1001M-2000W-Bass-Amp-Head/1WNV

lot's of mentions of 2000W no mentions of peak power here, I suspect both Gear4music and Music Group know people will choose this amp on the basis of the 2000W and it looks a lot better than the Little Mark 3 https://www.andertons.co.uk/bass-dept/bass-amps/bass-amp-heads/solid-state-bass-amp-heads/markbass-little-mark-iii-bass-head 

In practice I suspect they would produce very similar power levels. Even if the Veyron is 700W and the LM3 is 500w that difference will only barely be audible. Sensibly you'd decide on tone (I hope!) reliability, after sales and price rather than power but for someone with no technical ability that 2000W looks so tempting. If we accept this then Markbass would eventually be forced first of all to sell their amps at peak power of 1000W and then start making up figures to compete. I think it's a better world where honesty is rewarded and we ask for proper measured ratings which can be compared fairly.

 

Seems GFM can't even make up it's mind on the amps model number! It goes from a BV1001 in the title to a BV101M in the description. 

in the description it states Class D but in the video the guy from Bugera states it is Class C.

Maybe they are dyslexic or just plain forgetful...

[Count Bassy]

With industial servo amplifiers (to drive motrors) you tend to get a specification such as  6 amps continuous, 18 amps absolute peak for 2 seconds, 10 amps for 10 seconds etc. and generally get some sort of graph showing current again how long it it will deliver it for. However it is all very complicated, for example if you've just used 18 amps for 2 seconds, how long before you can do it again? 

If after the first 18 amps for 2 seconds it goes back to zero then you might be able to repeat it after 4 seconds (i.e. the average over 6 seconds is the continuous rating of 6 amps).

If after the 18 amps for 2 seconds it drops back to 5 amps then you might have to wait 26 seconds before you could do it again.

It all comes down to "Duty Cycle", but it's all very complicated. With servo drives you tend to work out what you think it needs, add a bit for luck, and see how it goes. This is why a lot of industial motors and drives are over specified - i.e. it's cheaper to over spec it than to underspec it and have to replace it.

 

[Chienmortbb]

On 17/11/2018 at 23:41, Phil Starr said:

Fair enough.

If we assume the Bugera is a well designed class D amp with an efficient power supply and draws 880W from the mains and can run continuously at that level then it is probably around 80% efficiency and can supply about 704W. That's with an undistorted sinewave within the passband of the amp. That's the value of what is normally described as the RMS or continuous value. If you look at section 3.2 of the Wikipedia article then you see the peak power of a sine wave is twice the average power. So if it is a 704W amplifier than the peak power is 1408W. If you look at a range of amp and speaker specs you'll see that there's a fairly consistent description of things described as 500W continuous 1000W peak, 200Wrms 400W peak and so on. It's a simple mathematical ratio which enables those who want to boast that their system is 1000W but allows for fair comparison. Actually it is meaningless as it is always double so no extra information is being given. If any other figure is given then as the Wiki article says about PMPO there is no accepted way of calculating the figure and it is without merit. Basically the sums don't add up.

you can see my disquiet if you look at the advertising, here for example https://www.gear4music.com/Guitar-and-Bass/Bugera-Veyron-BV1001M-2000W-Bass-Amp-Head/1WNV

lot's of mentions of 2000W no mentions of peak power here, I suspect both Gear4music and Music Group know people will choose this amp on the basis of the 2000W and it looks a lot better than the Little Mark 3 https://www.andertons.co.uk/bass-dept/bass-amps/bass-amp-heads/solid-state-bass-amp-heads/markbass-little-mark-iii-bass-head 

In practice I suspect they would produce very similar power levels. Even if the Veyron is 700W and the LM3 is 500w that difference will only barely be audible. Sensibly you'd decide on tone (I hope!) reliability, after sales and price rather than power but for someone with no technical ability that 2000W looks so tempting. If we accept this then Markbass would eventually be forced first of all to sell their amps at peak power of 1000W and then start making up figures to compete. I think it's a better world where honesty is rewarded and we ask for proper measured ratings which can be compared fairly.

 

As AGEDHORSE points out in a later post, I got my maths wrong as both peak  voltage and current are 1.414 times greater than their RMS values. Thersfore PEAK Power is almost twice "RMS". I have left the rest of the post intact but in the table below, Peak power should be 1414W and peak to peak 2827W all rounded to the nearest whole number.

 

Peak of a sine wave is 1.414  x RMS and Peak to Peak is 2 x Peak.

 

So can we believe that the Veyron is 707 Watts.  Are Uli's boys playing tricks on us? Well yes to both and it is the slight of hand that causes the problem. However as has been said already, it is a loud amp and is really good value. I have read most of the guff online about power and Rod Elliott has, as usual summed it up well on his site http://sound.whsites.net/power.htm

 

Incidently you will see a term Average power used on some HiFi sites and although not wrong, it is as wrong as RMS watts or RMS power. It should be just power but many, me included, like to say RMS to ensure that people know I am talking about the RMS voltage  X the RMS Current. Of course then you have the issue of distortion. If you quote a 10% figure it will still be inflated. I am happy for  1% figure to be quoted on a bass amp although I would like better than 0.1% for HiFi

Edited December 14, 2018 by Chienmortbb
Wrote somethimng stupid

[Guest gazzatriumph]

On 16/11/2018 at 01:09, chris_b said:

So you guys are saying that it doesn't matter how good an amp sounds, the only thing that matters is the design spec? Pull the other one!

TC were selling a 250 watt amp that was as loud as a 500 watt amp. The only "problem" you've got is they called it 500 watts. As it was as loud as a 500 watt amp then is anyone really going to feel short changed when they start gigging and find it is as loud as all the other 500 watt amps?

As I say the "noise" came from internet armchair experts. The guys who gigged those TC amps were happy their amps were performing well.

I have had TC RH750 head  and RS210 cabs for three years now and love em. Couldn't give a toss about figures I tried it,  liked it, and bought it and no GAS for anything else.  Its loud and sounds great.  Got rid of Ashdown ABM 500 and ABM 610 for it and never regretted it.  Louder and easier to move around.

 

Edited December 6, 2018 by gazzatriumph

[mcnach]

On 16/11/2018 at 01:09, chris_b said:

So you guys are saying that it doesn't matter how good an amp sounds, the only thing that matters is the design spec? Pull the other one!

TC were selling a 250 watt amp that was as loud as a 500 watt amp. The only "problem" you've got is they called it 500 watts. As it was as loud as a 500 watt amp then is anyone really going to feel short changed when they start gigging and find it is as loud as all the other 500 watt amps?

As I say the "noise" came from internet armchair experts. The guys who gigged those TC amps were happy their amps were performing well.

 

Indeed. I had one and didn't find it lacking in volume. I sold it because I preferred the sound of another amp, not because the TC felt underpowered. In fact, people used to comment how loud that little amp sounded when I first bought it... 

[Dan Dare]

Bill's right. It's pixie dust, really. Even RMS wattage claims are pretty meaningless. They may tell you how much an amp will heat an 8 ohm resistor for a few milliseconds, but into a reactive load like a speaker and across a full range of frequencies, that all goes out of the window. And that's before you start factoring in speaker efficiency, etc. Best to ignore all claims and audition stuff in real-world situations.

[ebozzz]

1 hour ago, Dan Dare said:

Bill's right. It's pixie dust, really. Even RMS wattage claims are pretty meaningless. They may tell you how much an amp will heat an 8 ohm resistor for a few milliseconds, but into a reactive load like a speaker and across a full range of frequencies, that all goes out of the window. And that's before you start factoring in speaker efficiency, etc. Best to ignore all claims and audition stuff in real-world situations.

👆 This......

[Chienmortbb]

23 hours ago, Dan Dare said:

Bill's right. It's pixie dust, really. Even RMS wattage claims are pretty meaningless. They may tell you how much an amp will heat an 8 ohm resistor for a few milliseconds, but into a reactive load like a speaker and across a full range of frequencies, that all goes out of the window. And that's before you start factoring in speaker efficiency, etc. Best to ignore all claims and audition stuff in real-world situations.

The only way to test and amp is into a resistive load and quote the continuous power (RMA amps x RMS voltage). That give s Average watts. Sadly some use RMS Watts. If you audition an amp or speaker it has to be against another amp/cab in the same room at the same time as our ears have no memory.  You may still get it wrong though as the room is a major component of your sound.

[JapanAxe]

I am sure everyone will be pleased to learn that this thread can now be closed, as I have confirmed in live tests that

|| AMPLIFIER WATTS ARE MEANINGLESS! ||

On 3 recent gigs I took out a 50W valve head where I normally would have used an 800W Class D head (with the same cab). Both were more than adequately loud, although different, but neither exhibited more heft than the other.

OK, please disperse to other threads, nothing to see here 🙄

[Muzz]

Ahhhh, but how did you know they were 50w and 800w? 😁