The “stated” guitar amp wattage doesn’t really seem to mean much

MTN

Silver Supporting Member
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193
More watts = more volume every single time..other things equal.
Perhaps mathematically, but in terms of human perception, there’s a lot more to it than that. I have a 30 watt Hi-Tone that volume-wise absolutely obliterates many 50 watt amps. Why? Because the simple mathematical relationship between wattage and dBLs doesn’t capture the true nature of what we really should be talking about, which is “audibility”, of which volume is a part, but isn’t the be-all-and-end-all. Extra wattage doesn’t help if a poor circuit design leads it to go to waste in useless low frequencies that muddy the sound.
 

Solude

Member
Messages
125
Watts is purely the maximum amount of voltage and current that an amp can provide before clipping. Power wise if you double the watts you go up 3dB in volume. So a 15W amp into a 100dB efficiency speaker will be the same output as a 30W amp into a 97dB speaker, 60W into 94dB etc. Given speakers can range from 85-105dB in efficiency you can understand why a 100W amp may be quieter than a 10W amp if they have different speakers.
 

Deluzion

Member
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1,323
I have a theory that clean watts delivered does not translate to db effeciency pushed straight to speaker. Some amps are more effecient at transfering its statedwatts to speaker. On top of this comes speaker effeciency and eq
 
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Besides just liking amps in general, I like having different amps with different sizes, speaker configurations, wattages, etc.
A Peavey Backstage amp works fine for learning new tunes, but certainly not for gigging. My ZT Lunchbox also works fine for home use, but could work small restaurant soft rock gigs.
Boogie Mark V 25, although rated 25 watts RMS, can keep up with most drummers I've worked with, etc.
Wattage ratings don't mean as much as: "Is there enough clean headroom for me to hear myself adaqutely on the gig I'm playing ?" and "Can the rest of the band hear me in a good ratio to how well they hear themselves ?"
 

Figaro

Silver Supporting Member
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12,768
Some amps are more effecient at transfering its stated watts to speaker.
I agree that this is at least part of the reason, if not all of the reason. We all know that amplifier components are not created equal. Some components (transformers for example) are just “better“ at providing the “stated” wattage.

Or... some provide MORE than the “stated“ wattage and others less than the “stated“ wattage?
 
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LaXu

Member
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6,602
Hey guys... I now would like to talk about the difference between two (or more) amps that are “stated” to be the SAME wattage. I changed the title of this thread to better reflect my opinion.

If they’re the same wattage (as stated) why is there many times a volume difference if they’re compared through the same speaker(s).

Do builders rate their amp wattage differently, correctly or honestly?
Is there not a standard for the “stated“ guitar amp wattage that they have to go by?
Most amps are rated at X watts RMS with low total harmonic distortion. Basically the amp's max output without overdriving the poweramp. "Marketing watts" are less common nowadays but used to be common in the past where they stated things like peak wattage or "music power" or "program power".

How are you comparing volume? You cannot compare the position of volume knobs on two different amp models. The sensible way to test how loud two different amps get is to hook them up to the same speakers and use a decibel meter to compare. Their frequency response will still have an effect on the perceived volume.

With solid-state amps you also need to be aware of output at different impedances so hooking up a 4 vs 16 ohm cab will give you different results even if both have the same speaker models. The manual usually states what output to expect at 4, 8 or 16 ohms.
 

56Tweed

Ge Fuzz-o-holic
Gold Supporting Member
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2,756
I agree that this is at least part of the reason, if not all of the reason. We all know that amplifier components are not created equal. Some components (transformers for example) are just “better“ at providing the “stated” wattage.

Or... some provide MORE than the “stated“ wattage and others less than the “stated“ wattage?
Maybe you are turning it up too loud, or not loud enough to meet what the builder's target volume setting was?

If you are going for a cleaner signal, it will use less power. If you are going for a heavy, driven signal, it will use more power.
 

Tone_Terrific

Silver Supporting Member
Messages
33,022
Do builders rate their amp wattage differently, correctly or honestly?
Not always.
Is there not a standard for the “stated“ guitar amp wattage that they have to go by?
No. There is common practice but no rules.
I have a theory that clean watts delivered does not translate to db effeciency pushed straight to speaker. Some amps are more effecient at transfering its statedwatts to speaker. On top of this comes speaker effeciency and eq
Nonsense. Wattage is measured AT the speaker.
And a watt is a watt no matter how it is created.
HOWEVER, a watt at 1000hz will be perceived as louder than a watt at 100hz even though they are being delivered at the same power level.

Amps and speakers with strong midrange emphasis are perceived as louder at the same wattage.

If you want an amp to be louder you turn it up. It delivers more wattage. It sounds louder.

It's when this does not happen that you have an anomaly.
There are many reasons for poor coupling between the speaker terminals and the ears of the listener.

The proper test is to try the amp in your application. It's good enough or not.
 

Deluzion

Member
Messages
1,323
Not always.

No. There is common practice but no rules.

Nonsense. Wattage is measured AT the speaker.
And a watt is a watt no matter how it is created.
HOWEVER, a watt at 1000hz will be perceived as louder than a watt at 100hz even though they are being delivered at the same power level.

Amps and speakers with strong midrange emphasis are perceived as louder at the same wattage.

If you want an amp to be louder you turn it up. It delivers more wattage. It sounds louder.

It's when this does not happen that you have an anomaly.
There are many reasons for poor coupling between the speaker terminals and the ears of the listener.

The proper test is to try the amp in your application. It's good enough or not.
Ok i didnt know the wattage was measured at the speaker. Still at what THD?

I bet if you took 50 amps into a anachoic chamber set em to outout all out at totally same THD and EQ'ed em to output its frequency as close as possible with a EQ with alot of band adjustment the DB ratings you would get would be soooo diffrent to what the maker states on their webpage on ALOT of these amps
 

Tone_Terrific

Silver Supporting Member
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33,022
Ok i didnt know the wattage was measured at the speaker. Still at what THD?

I bet if you took 50 amps into a anachoic chamber set em to outout all out at totally same THD and EQ'ed em to output its frequency as close as possible with a EQ with alot of band adjustment the DB ratings you would get would be soooo different to what the maker states on their webpage on A LOT of these amps
Guitar amps have very shaped voicings (eq) built in and not adjustable, as well as tone control.
Guitar speakers have very ragged response curves and vary greatly model to model.

Tube guitar amp builders cannot get away with much lying because the standard tube configuration potentials are well known and the power range that they can produce well-proven. That does not mean that they have to sound exactly the same, however.
 
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Alan Wolf

Silver Supporting Member
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464
Perceived volume is closely related to distortion levels. You can test this with a dB meter, your ears and a few sources. Clean, undistorted peaks can be much higher than distorted ones, and “sound” quieter.

Also, in tube amps, the iron matters a lot also. OTs saturate, lose their efficiency, PTs can also, so they stop delivering their rated current.
 

HotBluePlates

Member
Messages
10,656
... the difference between two (or more) amps that are “stated” to be the SAME wattage. I changed the title of this thread to better reflect my opinion.

If they’re the same wattage (as stated) why is there many times a volume difference if they’re compared through the same speaker(s).

Do builders rate their amp wattage differently, correctly or honestly?
Is there not a standard for the “stated“ guitar amp wattage that they have to go by?
... the difference between two (or more) amps that are “stated” to be the SAME wattage. ...

If they’re the same wattage (as stated) why is there many times a volume difference if they’re compared through the same speaker(s). ...
The simplest answer is "All Things Are NEVER Equal..."

 

HotBluePlates

Member
Messages
10,656
Adding on to what others have said, I'd look at the power supplies: rectification, filtering, power transformer resistance.

I'd also look at the output section: class of operation, tube type, feed to the output tube screens.

I'd think about where/when the amp's power section distorts, when/how the preamp distorts.

I'd think about amp EQ, speaker EQ, speaker sensitivity.

... If they’re the same wattage (as stated) why is there many times a volume difference if they’re compared through the same speaker(s). ...
Provide an example two amps with the same rated power, but one sounds very louder than the other through the same speakers. Just so we know this isn't a, "Why does my Tesla only get 7 miles per gallon?"
 

Harald

Member
Messages
148
Hey guys... I now would like to talk about the difference between two (or more) amps that are “stated” to be the SAME wattage. I changed the title of this thread to better reflect my opinion.

If they’re the same wattage (as stated) why is there many times a volume difference if they’re compared through the same speaker(s).

Do builders rate their amp wattage differently, correctly or honestly?
Is there not a standard for the “stated“ guitar amp wattage that they have to go by?
Usually the wattage is advertised @ x% THD. What happens above this point is not advertised, but with a tube amp it usually sounds good. Regardless, if you have the same topology (say 4 EL84 tubes in push/pull and not to much saturation in the output transformer) then if you measure sound level with same cab you will be close.

The rest is psychoacoustics.
 

teemuk

Member
Messages
3,178
Usually the wattage is advertised @ x% THD. What happens above this point is not advertised, but with a tube amp it usually sounds good.
In certain applications. Yet one doesn't see too many low power bass guitar, acoustic instrument nor PA tube amps because ultimately THESE do not sound very good "above that point".

Band-passing mids of signal from electric guitar pickups, and distorting that, can sound good. Then again, Leo Fender (Fender amps), Everett Hull (Ampeg amps) or Robert Crooks (Standel amps) would have not agreed. ;-)
 

Hulakatt

Gold Supporting Member
Messages
13,713
More watts = more volume every single time..other things equal.
Aye, there's the rub as they say. All other things are never equal and so many things affect the perceived loudness of an amp from the voice of the amp (which frequencies are pushed in relation to others) to speaker design and efficiency and the number of speakers to wether the amp is running through an open or closed back cab.

I don't care for turtles all that much unless they eat a lot of pizza.
 

Harald

Member
Messages
148
In certain applications. Yet one doesn't see too many low power bass guitar, acoustic instrument nor PA tube amps because ultimately THESE do not sound very good "above that point".

Band-passing mids of signal from electric guitar pickups, and distorting that, can sound good. Then again, Leo Fender (Fender amps), Everett Hull (Ampeg amps) or Robert Crooks (Standel amps) would have not agreed. ;-)
Correct, however distorted bass is hardly new and last time I saw these guys live I found out that distorted trumpet with reverb is pretty darn nice, too.


Having said that, I do admit that I was being very guitar centric above. Its not something that would go ovet well at the audiophile forums. :omg
 

ripgtr

Member
Messages
9,214
It has everything to do with playing in a band.
In a room by itself a 15 watt amp can really sound loud.
On a stage with drums and bass you will get buried trying to play clean chords with that same amp.
But as others have already said...I like turtles.
Depends on the band. I gigged for years and years with a SFDR. Country and blues bands, playing bars and what not. Plenty loud - most of the time. I went down and sat in with a friends band one time, and it was fine, till they did Moon Dance, and I was thinking I could play this nice jazzy solo on the neck pickup on it, but yea, it didn't cut it. But those guys were louder than the bands I was gigging in regularly. Plus not miced, which I would be on a paying gig.

A loud rock band? No. But I've played a crap load of gigs with a DR.
So it just depends.
 

Tone_Terrific

Silver Supporting Member
Messages
33,022
I was thinking I could play this nice jazzy solo on the neck pickup on it, but yea, it didn't cut it.
Running out of headroom when you need it will spoil your sound right away.
And there is a very narrow range between enough and too little.
To get that extra 3db to cut through cleanly requires twice the power.
To stay at the same level, with twice the power, allows your amp to loaf along at half power.
This seems to be often overlooked by those who state that their 50w amp is only 3 db louder than a 25.
It becomes far more obvious when you actually play in a situation where the extra depth of 50w allows you to play what you want to play.
This happens in all power ranges.
 




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