How does wattage relate to decibel level?

[jdfarrell81]

Hi all.

I'm assembling a new rig (300T, 610s, Concert Bass 215). The only complication is an impedance mismatch between the two cabs. The 2x15 is wired for 8 ohms; the 6x10 runs at 6 ohms. The 300T won't have any trouble accommodating the combined load--around 3.4 ohms or so--but I'm wondering how noticeable the difference in output between the two cabs will be. I'd like as close a match as possible.

I'm admittedly clueless concerning how wattage relates to decibels. Can I expect a significant difference in sound level between the 6 ohm and 8 ohm cabs? I know the 6 ohm cab will be louder, but if any of you can tell me how much louder, I'd really appreciate your help.

Cheers!

- James

[Wally]

IF you were to measure the resistance on that 2X15 cab, the 8 ohm cab will probably read about 6.3 ohms. I would think that the two cabs are fairly balanced in impedance.
I am not the one to educate you on wattage and decibels....other than the efficiency of the speaker/s and the amount of air they move (1X8 being much different than 6X10, for example in surface area of the cone/s) will determine how much volume(decibel level) any certain amount of power will produce.

[basiklybass]

As in the other post; there are no hard and fast rules about watts/decibels. What speakers? How many?

Some say; twice the power will be louder but not twice as loud whereas twice the speakers can sometimes make it seem twice as loud. Being a speaker guy, I say add speakers before you add power....once you are past 100 watts or so and especially if you are in the 300 watt range. Also look for efficient speakers rather than more watts.

As in auto racing, sometimes it takes 10 times the power to make it twice as fast/loud...and it gets expensive up there.

[EdBass]

As in auto racing, sometimes it takes 10 times the power to make it twice as fast/loud...and it gets expensive up there.

Great analogy! Several years ago I overheard the service director at a Porsche dealership respond to rapid fire questions about how much specific modifications would cost by politely interupting the customer and replying;
"Sir, speed is expensive. Now; how fast do you want to go?"

[Brianna1]

Hi all.

I'm assembling a new rig (300T, 610s, Concert Bass 215). The only complication is an impedance mismatch between the two cabs. The 2x15 is wired for 8 ohms; the 6x10 runs at 6 ohms. The 300T won't have any trouble accommodating the combined load--around 3.4 ohms or so--but I'm wondering how noticeable the difference in output between the two cabs will be. I'd like as close a match as possible.

I'm admittedly clueless concerning how wattage relates to decibels. Can I expect a significant difference in sound level between the 6 ohm and 8 ohm cabs? I know the 6 ohm cab will be louder, but if any of you can tell me how much louder, I'd really appreciate your help.

Cheers!

- James

When getting this technical I almost always refoer to my Indianapolis electrician.  However, my opinion is I don't think there will be a monumental difference but you will likely be able to hear it.  Are you going to be performing under these circumstances or recording?  If mixing or mastering I would suggest you fix the problem as you will need to be able to hear quality levels.  Good luck.

[noel]

The 610 will sound louder than the 215 but I suspect your ear will "blend" it pretty well because they'll be right next to each other.  Plus 10s and 15s have different sonic character so they should round each other out pretty nicely.  Ideally you'd want the exact same impedence but this shouldn't hurt...unless to your ears it just doesn't sound right.  The impedence the amp sees follows your calculation but the 610 will pull more of the current: P=(I^2)/R.  The impedence of the 610 is less so it will draw more current.   


Regarding your question about units, Watt and Decibels are both measures of power...just different scales.  One can convert between between the two easily:
10 log db(Pw)=Pdb

Just wiki decibels if you're really curious but the coloquial use of decibels in the guitar world is talking aobut db (SPL) which is the sound pressure level.  Basically how loud the amp is percieved to be.