impedance/speaker questions

[jrc]

Please forgive basic questions. Is volume affected between 4,8,16 ohm speakers. For instance, if I have an 8 ohm 30w speaker is it louder or softer than a 16 ohm 30w speaker (of course matching the impedance setting on the amp)?
Also, would a 4x12 cab loaded with 4 15w speakers 16 ohm for example be louder or softer than a 1x12 cab with 16 ohm 60w speaker? Is a 400w cab louder than a 100w cab used with the same amp? et cetera
I ask because I like it loud. I recently purchased a Komet 60 and I want to get this thing as loud as I possibly can. Any ideas, comments, suggestions will be greatly appreciated. Thanks

[SteveO]

Speaker efficiency is what you want to look at. The higher the efficiency (SPL) level, the louder the speaker will be.

[jrc]

Thanks SteveO. I'm sure there is a point where I would lose some of the sweetness this amp provides. So I guess what I'm looking for is to get it as loud and good as possible.

[ChorusCrackpot]

Like an amp, a higher wattage speaker has more headroom, so stays clearer and cleaner (less breakup) while delivering a high volume signal. Because the signal is less compressed by the 'breakup', more of it gets projected by the speaker, so has a louder volume.

Although, some speakers breaking up sound fantastic at really loud volumes.

[Ronsonic]

There has to be a good FAQ on this somewhere that goes into more detail than I'm willing to type.

In general speaker efficiency is what determines how loud a speaker will be for a given amount of power. It is traditionally rated as loudness, measured in decibels at one yard with one watt of power, for example "93dB efficiency."

Efficiency is not closely related to impedance. For the same model speaker available in different impedances, they will all have the same efficiency rating.

The power rating of a speaker only tells you how much power it can accept from the amp before bad things happen, like it overheats and dies. Power comes from the amp, not the speaker.

Also, would a 4x12 cab loaded with 4 15w speakers 16 ohm for example be louder or softer than a 1x12 cab with 16 ohm 60w speaker?

If the four speakers each have the same efficiency as the one speaker, they will be louder. Again, the power rating is something different from efficiency.

Efficiency, power rating and impedance are three different, unrelated things.
The impedance number tells you how to match the speaker(s) to the amp.
Efficiency tells you how loud it is at a given power.
Power rating tells you how much power you can apply to it before it pukes.

[TweeDLX]

I could be a victim of my failing faulty memory, but I seem to recall looking at some of the new Eminence speakers and being surprised that there was a difference in efficiency between same model speakers with different ohms. I believe this to be the exception, rather than the rule.
EDIT: This nagged at me, so I checked the Eminence site. While there was no variation between most of their speaker models (and I didn't check every one!), I did notice that the Texas Heat (great speaker BTW) 16 ohm is rated at 100dB, while the 4 & 8 ohm versions are at 99dB. Not a huge difference, but a difference.

[jrc]

Thanks for the info! I think it's time to experiment with some cab/speaker arrangements. The best speakers I have right now are celestion vintage 30 and classic lead 80. Looks like I'll need to search around for a place with different types I can demo. Anyone know of such a place in/near Cleveland?