collapse

Author Topic: Watts vs Volume (db)  (Read 42109 times)

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3144
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Watts vs Volume (db)
« on: December 22, 2010, 08:56:56 AM »
Everyone seems to think that they need more watts to get more volume.  While it is true that more watts will be louder than less given the same speaker, it is also true that the speaker is more important than the watts in most cases.

For every 10db gain (double perceived volume) you need a 10x multiplication of wattage.  So a 100watt amp is only twice as loud as a 10watt amp.  The reason this doesn't normally seem so is that 10watt amps normally have poor spl rated speakers, making the 100watt amp sound more than double the volume.  Playing through a better speaker will help increase your db rating, and hence your overall volume.

I've attached a chart to give you an idea of how an efficient speaker is louder than more watts on a less efficient speaker.

With this chart you can see that a 90db speaker on 100watts is less volume than a 102db speaker cab with only 10watts.  Most inexpensive amps come with speakers of about 90-93db.

To keep up with an average drummer you will want about 110db.  To reach this level you could use a 100watt amp with a single 90db speaker or you could run a small 10watt amplifier through a cab with rated 100db or better.

The calculation for total db is this:
{log (watts of amplifier) x 10} + speaker spl rating in db at 1w = total db output

Or if you want to figure out what db speaker (or cab) you need to hook into to get a certain desired db output:
Desired db output - {log (watts of amplifier) x 10} = Necessary speaker/cab db rating at 1w

Here is an excellent calculator for adding up speaker db and finding what the total output is: http://www.sengpielaudio.com/calculator-spl.htm

And thanks to Roly, another good table:

Speaker sens. (1dB/W@1m) Required power (watts)
104db1
101db2
98db3
95db6
92db12
89db24
86db48
83db96
80db191
77db382
Listener range 8 feet, desired listener SPL 80dB, amp headroom 15dB
« Last Edit: April 10, 2013, 12:13:26 PM by joecool85 »
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

trialabc

  • SSGuitar Regular
  • ***
  • Posts: 37
  • Chip Points: 0
    • View Profile
Re: Watts vs Volume (db)
« Reply #1 on: December 24, 2010, 02:03:37 AM »
But for what I have seen, most likely, there will not be db marked on the speaker. Usually I see Ohm and Watts.
What can I do if I can just see the two information marked? Perhaps the size can help?

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4141
  • Chip Points: 429
    • View Profile
Re: Watts vs Volume (db)
« Reply #2 on: December 24, 2010, 08:25:43 AM »
The datasheet sure helps.  ;)
If the speaker was a "house brand" one pulled from a guitar amp, as a "Jaguar" from a Randall, a "Fender special design" or an unnamed one from a Crate or Peavey, etc., they are almost always an OEM Eminence; most probably available to the general public as one of the "Legends".
Generic "Celestion inside" boxes most often have "Rocket 50" , sometimes V60 or at best "Seventy 80", being the least expensive ones.
Beware, they all sound good, it's just that they were not "used by Hendrix"

rowdy_riemer

  • Legendary
  • ******
  • Posts: 264
  • Chip Points: 13
    • View Profile
    • www.riemer.us
Re: Watts vs Volume (db)
« Reply #3 on: December 24, 2010, 12:32:02 PM »
You could possibly rig something up to do the measurements yourself. You can put a sine wave through your amp and hook up an oscilloscope across the speaker terminals. Then adjust the gain until you have one watt across the speaker. You might need to put a known resistance in series with the speaker to measure the current to help determine power since the exact impedance of your speaker at that frequency isn't going to be known (I guess you should use a 1 khz frequency for your test signal).

After knowing the power put through the speaker, you can then measure the dB spl, which I unfortunately am not to sure about how to do. Has anyone here made such measurements?

I bet someone could rig up an arduino board to both generate signals at a variety of frequencies and take measurements of the current through the speaker by measuring the voltage across the sampling resistor. And maybe even read the signal level from whatever microphone you use for db spl measuerments. Maybe after measuring all this, you can compare the impedance and frequency response curves with those from known eminance (or other manufacturer's) speakers to figure out which model was rebranded for your amp.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3144
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Watts vs Volume (db)
« Reply #4 on: December 28, 2010, 10:03:45 AM »
My little Dean Markley which is running at 20watts on a 92db speaker is pushing 105db or so.  If I ran it through a 4×8 cab with four 93db speakers that would get me up to 112db – enough volume for me to do some small gigs with it.  Although more likely I would get a Fender Frontman 65R as it pushes 111db stock on it’s built in speaker, or 120db with a 4×10 cab loaded with 96db speakers.  This would do small gigs on it’s own and most larger ones simply by plugging in a 4×10 cab.  To get the 120db needed for a larger venue with my Dean I would need to plug it into 3 cabinets of the 8×10 cab variety loaded with 96db speakers…you can see at this point more wattage is necessary.  There is definitely a diminishing point and I would say that 4 speakers is it really.  Maybe 8.
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

trialabc

  • SSGuitar Regular
  • ***
  • Posts: 37
  • Chip Points: 0
    • View Profile
Re: Watts vs Volume (db)
« Reply #5 on: December 30, 2010, 04:37:59 AM »
Thanks, now I get the general idea of it.

Sadly, I don't have instruments to do those testing. Perhaps I should buy the speaker with specification provided.

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4141
  • Chip Points: 429
    • View Profile
Re: Watts vs Volume (db)
« Reply #6 on: December 30, 2010, 05:44:10 AM »
To measure at home, you need an amplifier (*any* amplifier), download a "Pink noise MP3" , there's a few around or, worst case, I send you a sample, and a SPL meter, there's a Radio Shack one which is very affordable. U$45 the analog one; U$49 the digital one.
It's available almost anywhere thanks to those guys who want to set perfectly their "5.1" home theater systems, maybe somebody you know has one you can borrow for an hour or two.
You play your pink noise into the speaker through the "line input/loop return/Pwr amp in" , straight into the power amp , not through the preamp, and set the volume so you send 2.83 Volts into an 8 ohm speaker, 2V into 4 or 4V into 16.
In all 3 cases you are sending a nominal 1 Watt to the speaker.
You put your meter at 1 Meter distance pointing at the speaker and take the reading.
*That* is the naked truth, forget Marketing embellished datasheets.
You'll be surprised !!!
That's what they mean when they say: "X" Db SPL at 1 Watt at 1 Meter.
Without an SPL meter you can't take a numeric reading, but still can compare speakers for your own use, just play your pink noise as before, set it to 2.83 V and switch between both speakers back and forth, let your ears be the judge.
You will not only hear "volume" differences, but "response" differences, no two speakers will sound alike (unless same brand, same model, and sometimes not even so).
Do the experiment, it's very useful and mind-opening.

sound-pro

  • Chipper
  • *
  • Posts: 2
  • Chip Points: 2
    • View Profile
Re: Watts vs Volume (db)
« Reply #7 on: February 17, 2011, 03:48:48 AM »
A factor seldom taken into consideration is that with higher power available for less per watt, speaker elements have grown less efficient because they have to be designed to handle more power.

There are a couple ways to make a dynamic element more able to withstand higher power. You can increase the voice coil wire size, which adds mass which lowers efficiency.

You can make a speaker able to handle further excursions of the diaphragm which presents a problem. The suspension of the cone needs to be more compliant, to be able to move to greater extremes. The means the concentrically of the voice coil in the pole piece(the magnet gap into which the VC is placed) worsens. At any given instant the position of the center axis of the VC and the pole piece is less known, with more variability. To solve the resulting rubbing that can result from less precise VC placement during it greater excursion, the gap is made wider. That decreases flux concentration which reduces driver efficiency a great deal deal.

The suspension can be made stiffer instead of increasing the pole piece gap. That also increases efficiency.

 High power speakers, as a general rule, are less efficient than speakers of the same size that are designed for less power so more power is needed for the same acoustic power coupled to the room.
An array of small, efficient speakers in appropriate cabinet at any mid point frequency will create more acoustic power per watt.
But guitars are not signal generators operating at a single frequency. The speaker/amp/guitar combination is interested in specific parts of the spectrum, not the full audio spectrum. Speaker specs such as sensitivity are general clues but since they are taken at a specified very easy to produce frequency, usually 1khz or 400hz, the spec does not tell you as much as you might want to know in predicting how loud a particular combination of cab/driver/amp will sound like.
Flat frequency response is not a major goal in guitar amps so cabinet tuning is usually not done, which can greatly influence speaker efficiency as a system. But the tone difference between cabinets becomes pretty dramatic when a driver is working into an restricted infinite baffle style cab, like open back combo's usually are.
The question is, what efficiency do you get get in the portion of the spectrum your music requires to produce the tone you want? The specs on a spec sheet for a raw driver tells very little about that. Almost any speaker can be made to sound like any other but not at the same efficiency. Compare the flat linear response from a tight pole piece system in a horn, such as the Klipshorn or even the Altec folded midrange horns, and their great efficiency to your current 200watt blaster master driver. 1 watt, through most of the audible spectrum will drive you out of the house, 60 watts fills auditoriums. But 100 watts would burn up their highly efficient drivers.
Guitarists can get a closer approximation of their desired tone character from speaker experiments than anything they can do with their amps. The harmonic spectra generated by a speaker in appropriate cab or baffle can be very muscial, particularly with tube amps because of the lack of damping tube amps with little or no negative feedback have to control the fidelity of the cone movement to the signal level. Solid state amps, usually have a high damping factor so control the absolute fidelity of cone position to signal instantaneous level much better. That means less distortion generated by the cab alone. That is great for "reproducing" sound but less desired in "creating" sound. More attention needs to be payed to the amp signal impressed on the speaker in solid state because of that great control of the sound produced than with a tube amp.
A tube amp might sound good in a particular style of play but not in another because the amp and speaker are pretty much free agents doing as they please despite the intent of the other. As a result of that fact, solid state is more versatile and can handle a wider range of material, but needs to take more responsibility for the resulting sound. There is a lot more potential, but underused, upside potential in good SS designs. Given that the speaker is less a free agent, not imparting its character completely on the sound as much as tube gear allows, the player is freer to experiment with speaker/cab designs that have greater efficiency, without worrying too much that some mysterious mojo smoke might escape.
If you can create the transfer function of the sound you want, you can get it from a wider range of speaker choices and designs, but get it you will with solid state.
Players usually do not know that they are in control of the tone and are responsible in solid state. A high power amp, much more powerful than the speaker can handle is not a bad thing....unless a player treats the combo like a tube amp/speaker.
If they focus on tone, at a moderate lower SPL, the power section will simply provide the drive and not impart any particular sound character to the signal. In that way, the same tone can be had at various power levels. So why try to overpower the speakers when you already have the tone dialed in at 1/10 th the power? Maybe because they grew up with tube gear that did not sound the same at different power levels, and the sweet spot for a lot of desired tone was between 99 and 110% of amp capacity. They HAVE to run high power to get tone. A solid state user only overpowers their cab or gets close to clipping the power section due to misunderstanding their system.
The usual comment is thst "I need to get over the drummer". That is not an acoustic power problem, that is a personality problem. The audience is not going to be left in the dark as to whether you are playing or not dropping to YOUR rig's sweet spot which is any level well under clipping of the amp and within comfortable excursion limits of the speaker. In the very few situations where the guitar just did not stand out because of volume level, it becomes a problem for the house PA system to fill the need. Because you have 400 watts of SS power does not mean any person in the audience will enjoy it any better running at clipping. In fact, just the opposite is the case, all improves with lower stage volume...vocals, guitars playing, dynamic range of the whole group etc. If the band can't "balance" themselves, but instead run flat out in all instruments, it is boring and not musical.
If the drummer can't play as a member of a team, fire them, they have no business in a team. Play in your sweet spot, not the drummer's ego trip. A club with 200 audience does not need much power to fully fill their consciousness. Anything bigger has a PA system that is designed to do that. But to sound good, you much take responsibility for the overall sound, not just on stage but also in the hall so be prepared to fire the sound guy if they are playing ego trips with power, his job is to compliment your sound by re-enforcing it, not creating it. If you are not having at least 20 db headroom in the house system your music is dead and lifeless in dynamics, but most systems by dead ear sound guys are pushed to have 3 or less total DR between average and peaks levels. Take control, it is your career.

All this comes back to speakers. With solid state the choice and design or even power are not the major tone consideration it is with tube gear, if sensible levels are used that compliment your music.

This is from the perspective of a recording engineer, EE, gear designer and audience member, not a player.




joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3144
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Watts vs Volume (db)
« Reply #8 on: February 17, 2011, 06:09:30 AM »
Holy cow!  I read that whole thing.  Very interesting indeed, and great first post!
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

sound-pro

  • Chipper
  • *
  • Posts: 2
  • Chip Points: 2
    • View Profile
Re: Watts vs Volume (db)
« Reply #9 on: February 17, 2011, 02:39:02 PM »
Sorry about the length, sometimes I get carried away with a theme, in a stream of consciousness text, typos and all.
In all music, I am more concerned with the audience than the players or sound guy since it is apparent in live gigs the only ones not considered is the audience. The band, roadies, monitor mixer and house mixer, all have their own tastes go by but no one actually consults with or goes out into the audience to see how it sounds or if the audience is even enjoying it.
In recording I always assumed that role of being the audience's representative in the session. It seems to have worked based on the records on the walls.

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3144
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Watts vs Volume (db)
« Reply #10 on: February 17, 2011, 03:15:50 PM »
Sorry about the length, sometimes I get carried away with a theme, in a stream of consciousness text, typos and all.
In all music, I am more concerned with the audience than the players or sound guy since it is apparent in live gigs the only ones not considered is the audience. The band, roadies, monitor mixer and house mixer, all have their own tastes go by but no one actually consults with or goes out into the audience to see how it sounds or if the audience is even enjoying it.
In recording I always assumed that role of being the audience's representative in the session. It seems to have worked based on the records on the walls.

Very interesting.  Can you share who you've done recording with/for?
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

Jack1962

  • Elite SSGuitarist
  • *****
  • Posts: 249
  • Chip Points: 4
    • View Profile
Re: Watts vs Volume (db)
« Reply #11 on: April 11, 2011, 11:56:59 AM »
Great 1st post indeed Sound-Pro
however , there are many way's to get more volume out of your amp , the easiest way is to add a more efficient speaker , or multiple speakers that works fairly well.
Joecool what 100 watt amp do you have that has only 1 speaker , to compare to a 10 watt .
my 100 watt amps blow away ANY 10 watt amp with as many speakers as you want to attach to the 10 watt amp with my 100 watt am on 1 lol lol lol

                                                Rock On

joecool85

  • SSGuitar Admin
  • Legendary
  • ******
  • Posts: 3144
  • Chip Points: 984
  • SSG Creator
    • View Profile
    • thatraymond.com
Re: Watts vs Volume (db)
« Reply #12 on: April 11, 2011, 04:29:17 PM »
Great 1st post indeed Sound-Pro
however , there are many way's to get more volume out of your amp , the easiest way is to add a more efficient speaker , or multiple speakers that works fairly well.
Joecool what 100 watt amp do you have that has only 1 speaker , to compare to a 10 watt .
my 100 watt amps blow away ANY 10 watt amp with as many speakers as you want to attach to the 10 watt amp with my 100 watt am on 1 lol lol lol

                                                Rock On

It was a theoretical situation pointing out how important speakers are.  That said, most 100w amps will have 2x12" speakers with a fairly high spl rating while most 10w amps will have a low spl 8" speaker, this makes the volume discrepancy quite large.
Life is what you make it.
Still rockin' the Dean Markley K-20X
"New" amp: Fender Frontman 25 DSP (FM25DSP)
thatraymond.com

J M Fahey

  • SSGuitar Global Mod
  • Legendary
  • ****
  • Posts: 4141
  • Chip Points: 429
    • View Profile
Re: Watts vs Volume (db)
« Reply #13 on: April 11, 2011, 06:31:50 PM »
Yes, that's where 90% of the discrepancy lies, 99.9% of small, cheap amps have *very* cheap (and poor) speakers.
The 10 to 100W comparison is acceptable if both are driving the same cabinet (say, a 4x12" Marshall) and there is no other loud sound source (such as a drummer) to confuse your ear.

bry melvin

  • Elite SSGuitarist
  • *****
  • Posts: 168
  • Chip Points: 13
    • View Profile
    • Recent Album
Re: Watts vs Volume (db)
« Reply #14 on: April 12, 2011, 04:00:41 AM »
one factor everyone forgets about is frequency!  I often use a Fender 25 R for my steel... you can definitely hear it in the mix.

My bassist however cannot use her 60 Watt Acoustic practice amp with it (the Acoustic Brand not FOR acoustic)
25 wats is then > 60. seemingly.

She does use that amp when we're doing unplugged stuff...doesn't own an acoustic bass. And to agree with what's said before...get a different drummer. Two dreadnoughts electric bass and a drummer works for our acoustic blues gigs. And actually when I switch to the 000 for a few songs it pierces through to the top as it is less bassy...have to back away from the mikes.

Because we simply don't hear bass as well.

On the same token, scooping the midrange out makes an amp apparently softer then the same levels clean because we hear midrange best...That's why my steel and mandolin can get through the mix with much less power.

Actually for a too loud drummer buy him electronic drums...turn his earbuds up and turn him down in the mix  :lmao:
« Last Edit: April 12, 2011, 04:03:22 AM by bry melvin »

 

* User Controls

 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?

* Recent Posts

Vintage 1967 Astro Amp by tigerzilly
[March 19, 2019, 08:17:21 PM]


Variable resistor on marshall scheme by Jazz P Bass
[March 17, 2019, 11:59:01 PM]


Operational Amplifier in Marshall 5010 scheme by Jazz P Bass
[March 17, 2019, 11:48:21 PM]


HELP Marshall 5203 Master Reverb 30 by g1
[March 10, 2019, 09:32:40 PM]


Help with Gallien-Krueger 200GT guitar amp by phatt
[March 09, 2019, 11:06:26 PM]

* Sponsors