Loudness When Using Extension Speaker

Robin Nahum · February 9th, 2005, 01:22 AM

I am wondering what happens to overall loudness when you use two speakers instead of one.

As a specific example, suppose I have a one speaker amp, like a Vibrasonic (just to give DRs a rest), and I then attach a second identical speaker using the extension speaker socket, how much louder will the overall output be in db?

Is there a way of calculating this?

The volume and tone controls on the amp and guitar remain unchanged of course, and it can be assumed that the second speaker is also in an open back enclosure.

Ringo · February 9th, 2005, 01:52 AM

Hi Robin
I've experimented with Fender amps using ext cabinets, didn't really notice a dramatic increase in volume per se, but the sound is bigger, fuller, you can certainly "feel" the difference.
I'm sure someone here or on the Weber amp BB can tell the scientific explanation, there was a recent post about volume vs watts, seems like you had to really increase the wattage of an amp for every few decibles in volume.

Daddy Elmis · February 9th, 2005, 09:42 AM

I'm no expert, but I believe the issue here is an increase in sound pressure level (SPL) with extension, or additional, speakers. This is not an actual increase in dB, but will be perceived as "louder" because the SPL is higher (you are moving more air with the sound waves). Also, you should get a bit more clean headroom as more speakers are sharing the load so speaker distortion will be less (the tube distortion will be the same).

The watt vs. dB formula does show the logarithmic relationship between an amps power in watts versus a change in dB (i.e., a 10 watt amp is 1/2 as loud, in dB, as a 100 watt amp), but this is only one facet of perceived "loudness" as we all know when we listen to 2 identical amps and one "sounds" louder than other. Tone stack, speakers, cab, guitar, and lots of stuff affect what we perceive as "loudness."

1612112 · February 9th, 2005, 08:30 PM

With the extra speaker you'll be moving more-air-less instead of less-air-more. Which is a good way to go.

dB is an measured increment of SPL and neither should be effected dramatically. It will appear louder but that's only because for once you'll be able to hear it over the drums and bass. The reason for this is that you are moving a larger "Volume" of air. The knob on the front of most amps marked "Volume" is misleading in that respect, because it controls loudness not volume.

pjb

February 9th, 2005, 01:22 AM	#1 (permalink)
Robin Nahum Tele-Afflicted Join Date: Mar 2003 Location: Sydney, Australia Age: 57 Posts: 1,732 13 Photos	Loudness When Using Extension Speaker I am wondering what happens to overall loudness when you use two speakers instead of one. As a specific example, suppose I have a one speaker amp, like a Vibrasonic (just to give DRs a rest), and I then attach a second identical speaker using the extension speaker socket, how much louder will the overall output be in db? Is there a way of calculating this? The volume and tone controls on the amp and guitar remain unchanged of course, and it can be assumed that the second speaker is also in an open back enclosure. __________________ RN

February 9th, 2005, 01:52 AM	#2 (permalink)
Ringo Tele-Afflicted Join Date: Mar 2003 Location: Memphis TN Posts: 1,927	volume vs fullness Hi Robin I've experimented with Fender amps using ext cabinets, didn't really notice a dramatic increase in volume per se, but the sound is bigger, fuller, you can certainly "feel" the difference. I'm sure someone here or on the Weber amp BB can tell the scientific explanation, there was a recent post about volume vs watts, seems like you had to really increase the wattage of an amp for every few decibles in volume.

February 9th, 2005, 08:30 PM	#4 (permalink)
1612112 Tele-Meister Join Date: Nov 2004 Posts: 229	Loudnes vs Volume With the extra speaker you'll be moving more-air-less instead of less-air-more. Which is a good way to go. dB is an measured increment of SPL and neither should be effected dramatically. It will appear louder but that's only because for once you'll be able to hear it over the drums and bass. The reason for this is that you are moving a larger "Volume" of air. The knob on the front of most amps marked "Volume" is misleading in that respect, because it controls loudness not volume. pjb

February 9th, 2005, 09:42 AM	#3 (permalink)
Daddy Elmis Tele-Holic Join Date: Jun 2004 Location: USA Posts: 961	I'm no expert, but I believe the issue here is an increase in sound pressure level (SPL) with extension, or additional, speakers. This is not an actual increase in dB, but will be perceived as "louder" because the SPL is higher (you are moving more air with the sound waves). Also, you should get a bit more clean headroom as more speakers are sharing the load so speaker distortion will be less (the tube distortion will be the same). The watt vs. dB formula does show the logarithmic relationship between an amps power in watts versus a change in dB (i.e., a 10 watt amp is 1/2 as loud, in dB, as a 100 watt amp), but this is only one facet of perceived "loudness" as we all know when we listen to 2 identical amps and one "sounds" louder than other. Tone stack, speakers, cab, guitar, and lots of stuff affect what we perceive as "loudness."