so why are 2 amps louder...

Dave Van Allen · Post by **Dave Van Allen** » 19 Nov 2002 11:34 am

than one amp of twice the wattage?

say two 50 watt amps versus one 100 watt?

I know there's a formula for how much power it takes to double perceived volume, that figures in it....

Please enlighten me. Thanks.

chas smith R.I.P. · Post by **chas smith R.I.P.** » 19 Nov 2002 1:34 pm

Because 2 amps would have 2 speakers and that would be twice as much air moving to your ears. Also, the 100 watt amp isn't twice a powerful as the 50 watt amp, the 500 watt amp is twice as powerful.

Buck Dilly · Post by **Buck Dilly** » 19 Nov 2002 2:20 pm

Twice the wattage does not mean twice the loudness. Wattage is a power rating. Two fifty watt amps will create more intensity and move twice the air as one-fifty watt amp. High wattage produces clean power which offers cleaner attack (less compression.) Wattage has a logarithmic effect. In order to get twice the loudness (db's), you will need a lot more than twice the wattage. However. The attack will be percieved as louder in one 100 watt amp.

Donny Hinson · Post by **Donny Hinson** » 19 Nov 2002 3:59 pm

Who says they are?

While it's true that two lower-powered amps may move more air, they still won't give you all the tonal capabilities (as far as bass response goes) that one big amp will! If it were true that multiple amps were such a good thing, sound-wise, we'd see the top steelers playing through four or five 40-50 watt amps...and this just ain't happenin'.

However, if you're not very interested in the low-end response, this can be a usable configuration...and that's why it's popular with some rock players. They are more interested in "how loud it will go" than they are with "how good it sounds".

John Bechtel · Post by **John Bechtel** » 19 Nov 2002 4:52 pm

Donny; As a matter of fact, the top steel players from Nashville do use two amps! And if not, they use one Stereo Pre-amp w/2 power-amps! "Big John" http://community.webtv.net/KeoniNui/doc [Not a top player!]

Donny Hinson · Post by **Donny Hinson** » 19 Nov 2002 5:28 pm

I've seen that , John. However, most all of them use 2 big amps (100 watts or more, each)...not 2 small ones (with 50 watts or less). I once saw Chalker playing through 2 Session 500's! Needless to say, it got the job done.

Bill Llewellyn · Post by **Bill Llewellyn** » 20 Nov 2002 8:00 am

JayDee Maness used two (Evans) amps at a recent jam I hosted. Some other players had dual amp or dual speaker setups, too, like David Wright and Frank Carter (both superb players as well).

Loudness and power are funny things. To double the loudness of a sound, you have to quadruple the power. So to get an amp which is twice as loud as a 50W amp you need to go to a 200W amp. Really. (It's a square law thing.) This brings up a few interesting points:

1. A 100W amp is not twice as loud as a 50W amp. It is only 40% louder.

2. If you put a 50W amp in a room and make it play at 50W, you get X loudness. If you put another 50W amp next to it and have it play at exacly 50W also, you will get 100W of sound but it will not be twice as loud (2X). (Huh??) It has to do with the mechanical impedance of the atmosphere as a transmission medium. (WHAT??? Stop right there, Bill!!! No more mathematical gobbldygook.)

Two 50W amps may seem more than twice as loud as one 50W amp, but that may have more to do with the fact that you can aim them for better dispersion or because you didn't make your experiment with both of them set to EXACTLY the same volume both before and after you turned one of them on or off. Too many variables! It's easy to get fooled when tinkering with amps and things whose operation depends on numerous knobs, the way the input source (guitar) is being played, the position of the speaker, closeness to walls, room carpeting, ceiling height, and so on.

Also, when I state that one amp is 50W and another is 100W, everything else about the amplifiers needs to be the same for an accurate comparison. If the 100W amp has a bigger cabinet and a different speaker, it may be more (or even less) efficient for reasons which have nothing to do with power levels, totally messing up the comparison to the 50W amp. Again, too many variables!

Isn't this fun?

Bobby Boggs · Post by **Bobby Boggs** » 20 Nov 2002 8:14 am

Ok I'm trying to learn here.Chas says 500 to double a 50 watt amp.Bill say's 200 to double a 50 watt.

Bill Llewellyn · Post by **Bill Llewellyn** » 20 Nov 2002 8:45 am

Bobby, it can be confusing. Remember that when you go from a 50W to a bigger amp like a 500W, lots of things change--speaker size, cabinet size, maybe the speaker impedance, even tone and effect features--which can effect how loud the amp sounds in addition to the wattage difference.

Regarding my statement about needing to quadruple the power to get a doubling in loudness, it's just a bit of engineering math:

Power = Voltage squared / Speaker resistance
P = V**2 / R (or P = V^2 / R)

Loudness varies directly with the voltage applied to the speaker. If your double the loudness (doubling the voltage), that factor of 2 gets squared in the power equation which results in a power increase by a factor of four.

I'll throw in another big confusion factor here. (Wait a minute, aren't I supposed to be helping clarify things?) In my discussions above, when I speak of watts (50, 100, whatever) I'm not talking about the amplifier maximum rating, I'm talking about a specific amount of power actually being delivered in an experiment. A 200W amplifier gets twice as loud as a 50W amp if and only if they are both rated for maximum power in exactly the same way. Is it 50W measured at 1% distortion versus 200W measured at 10% distortion? Or both rated at 0.01% distortion? There is no absolute standard out there for this. If I buy a 50W amp rated at 50W @ 1%THD and you buy an amp rated at 100W @ 10%THD (THD = total harmonic distortion), they may actually have the almost same true maximum power capability! (I'm not saying these two ratings are identical, I'm just using them as a loose example.) Confusing? Yes....

Anyway, twice the loudness = four times the power when comparing two amps in which all other factors are identical. Regarding whether one amp rated at 200W seems twice as loud as another rated at 50W, it depends on a whole buncha variables, including the way the manufacturer's power rating is determined.

Did that help?

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Bill L | My steel page | Email | My music | Steeler birthdays | Over 50?

[This message was edited by Bill Llewellyn on 20 November 2002 at 08:46 AM.]

Steve Stallings · Post by **Steve Stallings** » 20 Nov 2002 10:37 am

Bill,
I've spent a considerable amount of time studying audio and sound over the last ten years. I'm not sure I understand your statement as it does not appear to agree with fundamental audio engineering theory. Maybe I just missed class that day

A basic premise is that to simply increase the perceived loudness (a 3db increase) requires doubling the power. To actually double the volume is a log function of 10 requiring 10 times the power. We have to assume we are speaking of RMS and not peak power.
This actually is much more complicated than that, but that is trivia for sound engineers

Here is an easy to read and understand article with charts that specifically addresses this issue. http://www.gcaudio.com/Archives/volatgeloudness.htm

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God Bless,
Steve
John 3:16

Stephen Gambrell · Post by **Stephen Gambrell** » 20 Nov 2002 12:38 pm

OK, Bobby, here is the simplest formula I can find, maybe it'll help you sort through some of this. BTW, Steve Stallings has it about right, but he's left out some stuff that's relevant to YOUR case. Ready? OK!
1. If you can hear your wife on the phone, asking the club owner when the band will be through, you're not loud enough.
2. Average the volume of the last three shootings you heard on the job. If you could only hear ONE gunshot, you're about right.
3. If the bass player gets more good-looking girls than the lead guitar player, you're too loud.
In summation, if you play as good as Bobby Boggs, it doesn't matter if you're playing through a Vibro Champ, cause people WILL listen! God bless you, boy!

Bill Llewellyn · Post by **Bill Llewellyn** » 20 Nov 2002 2:55 pm

Steve, I took a look a the page you linked. Nice page! And it actually supports all of what I was trying to say, with no disparities I can see. I may just not have said it very clearly. They happened also to put the relationships between dBV, voltage, and power that I was trying to express into table form. Very concise.

What I think you are alluding to in the discussion here is the human perception of loudness--issues such as what constitutes "twice as loud", what constitutes the smallest perceptible change in volume, stuff like that--which was not quite what I was talking about. That involves perceptual studies, A-weighting curves, thresholding, and stuff like psychoacoustics. Those issues make comparing the apparent loudness of dissimilar amplifiers, even if they have the same power rating, kind of complicated.

Bobby Lee · Post by **Bobby Lee** » 20 Nov 2002 11:41 pm

There's no such thing as "twice as loud". There's "not loud enough", "loud enough", and "too loud". People disagree about those things all the time.

I can't imagine how a sound can be "twice as loud".

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<img align=right src="http://b0b.com/b0b.gif" width="64" height="64">Bobby Lee - email: quasar@b0b.com - gigs - CDs
Sierra Session 12 (E9), Williams 400X (Emaj9, D6), Sierra Olympic 12 (F Diatonic), Sierra Laptop 8 (D13), Fender Stringmaster (E13, A6), Roland Handsonic

Jim Cohen · Post by **Jim Cohen** » 21 Nov 2002 5:00 am

This all has to do with the "Stevens Power Law" or "Weber-Fechner Law" of Psychophysics. I used to know all about that. Ah, but I was so much older then, I'm younger than that now...

Dave Van Allen · Post by **Dave Van Allen** » 21 Nov 2002 5:29 am

There's "not loud enough", "loud enough", and "too loud".

you're right b0b... once again I've been "over-thinking" it.

thanks for the explanations and links folks.
<BLOCKQUOTE>quote:<HR>

NIGEL:
This is a top to a, you know, what we use on stage, but it's
very...very special because if you can see... 

MARTY:
Yeah... 

NIGEL:
...the numbers all go to eleven. Look...right across the board.


MARTY:
Ahh...oh, I see.... 

NIGEL:
Eleven...eleven...eleven.... 

MARTY:
...and most of these amps go up to ten.... 

NIGEL:
Exactly. 

MARTY:
Does that mean it's...louder? Is it any louder? 

NIGEL:
Well, it's one louder, isn't it? It's not ten. You see, most...most
blokes, you know, will be playing at ten. You're on ten here...all
the way up...all the way up.... 

MARTY:
Yeah.... 

NIGEL:
...all the way up. You're on ten on your guitar...where can
you go from there? Where? 

MARTY:
I don't know.... 

NIGEL:
Nowhere. Exactly. What we do is if we need that extra...push
over the cliff...you know what we do? 

MARTY:
Put it up to eleven. 

NIGEL:
Eleven. Exactly. One louder. 

MARTY:
Why don't you just make ten louder and make ten be the top...
number...and make that a little louder? 

NIGEL:
...these go to eleven. <HR></BLOCKQUOTE>
I think we can close this one now....

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"I AM Z-BOY!"

Zumsteel U12 "Loafer" 8&6 :: ZB Custom D-10

:: Fender Tube Amplification
www.voicenet.com/~vanallen/ :: vanallen@voicenet.com :: www.lasttrainhome.com

Bill Llewellyn · Post by **Bill Llewellyn** » 21 Nov 2002 7:29 am

Bob,

Early acousticians came up with a simple method of comparing two sounds. A sound that was perceived to be twice as loud as another sound was said to be one Bel greater in sound level.

This is from http://www.soundinstitute.com/article_detail.cfm/ID/128

I'd heard about that origin of the "Bel" as being an attempt to quantify what humans perceive as "twice as loud." The Bel turned out to be too large for practical use (see article, above) so it was decimated

and made into decibels (1/10 Bel), or dB.

Steve Stallings · Post by **Steve Stallings** » 21 Nov 2002 12:49 pm

Bill,
Thanks for the informative link. I always enjoy reading this stuff, but am still tickled to realize that b0b is right:
not loud enough, loud enough, too loud

As an aside, you really have to marvel at the design of the human ear. Of course, considering the designer...

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God Bless,
Steve
John 3:16

Michael Brewer · Post by **Michael Brewer** » 21 Nov 2002 1:29 pm

I'm not sure that this is the place to put this but, here is a gadget that will increase the sound of any open back amp at least 20% without any additional wattage.

It is called an "Enhancer". It captures the sound coming out of the back of the amp and redirects it forward while tipping the amp back about 30 degrees. All of us who use an open backed amp direct about 30% of our sound backwards.

I just bought one and it's a lot cheaper than carrying around two amps. It weighs only 29 lbs.

If any one is curious, email lawsounds@aol.com

Mike Brewer

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Mike Brewer

chas smith R.I.P. · Post by **chas smith R.I.P.** » 21 Nov 2002 1:50 pm

Sounds like sort of a "bolt-on" bass reflex enclosure without the tunable port.

ajm · Post by **ajm** » 21 Nov 2002 6:42 pm

Michael;

Not to second guess or criticize you, but if by chance the amp is pointed up towards your head and not at your knees it's probably going to sound louder. I trust that you took this into account when doing your tests.

However, I do agree that a lot of sound goes out the back of an open back amp. Kudos to you for noticing this. I was in a bar not too long ago and the guitar player was using an amp that I'd never seen before. I couldn't figure out what it was. The reason? He was using a Deluxe Reverb, but it was turned around facing away from the crowd. He was not mic'ed, and even though the band was about average in terms of loudness, you had no trouble hearing him.

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Artie McEwan

Michael Brewer · Post by **Michael Brewer** » 23 Nov 2002 5:57 am

Artie,

I don't want to take credit for this idea. I wish it was mine. I think the "Enhancer" is going to become very popular. Players have been tipping their amps back for as long as I have been playing and the people who are producing this unit are just incorporating this practice into their product.

Again, anyone who wants to find out more about it can do so by e-mailing lawsounds@aol.com.

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Mike Brewer

Kenny Dail · Post by **Kenny Dail** » 24 Nov 2002 8:17 pm

Damn! Who says "old dogs can't learn new tricks"?

I am always told to lower my volume followed by, "we can still hear you".

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kd...and the beat goes on...