amplifier DB meters

Arthur, nice answer.
To expand on that, when listening at 2 watts, if you want to double your perceived volume, you need to increase volume by approximately 10db. Each 3db required a doubling of power. That translates into about 18-20 watts continuous to just double from "mellow" to more. That's why we need 100/200/300 watt amps just to handle the dynamic peaks which can be much louder...

Helio, When my system is playing and I only ever see 4 watts on the meter with the loudest peak, I can figure that the amp is using more watts, than the meter is reading, but how much more? Assuming that the meter is correct - a big assumption I gather - I know I would need a more powerful amp than 4 watts.
I know that this is one of those impossible to answer questions when you figure in the variables ; probably impedances, speaker type etc. I can be pretty well assured though a 400 watt amp can handle the peaks, but what about 100 watt or 40 watt? Any ideas of how much headroom is needed?
Bob

Hi Bob, VU meters usually have averaged response and don't show the peaks. LED-style units exist that do show the peaks; having watched a lot of these it appears that your typical peak is 3-6 db above the reading on an averaging meter, IMMV (definitely not cast in concrete)

6 db is 4x amplifier power, in your case 16 watts, to be safe in this case I would allow for at least double that.

Since our ears operate logarithmically, that's not a huge increase and is the root of the term 'gold plated decibels'. This is why speaker efficiency is such a big deal.

When my system is playing and I only ever see 4 watts on the meter with the loudest peak, I can figure that the amp is using more watts, than the meter is reading, but how much more?

4 watts metered power (referenced to an 8 Ohm load) is;

1) is actually 60 watts into a 0.5 ohm load. In this case, the limiting factor, however, will NOT be the watt rating of the amplifier but the current limitation (11 amps of current is required at 60 watts when driving a 0.5 ohm load and most amps will not deliver anything close to this level of current unless they are rated 1000 watts or more and designed to handle very low impedance loads and high current output...so basically your amp will be current limited at some point ...usually around 7 amps for a 200 watt amp and the meters on the display will, of course, never exceed 4 watts)

2) is actually 15 watts into a 2 Ohm load.

The above is a hypothetical example but it illustrates how power meters can be completely misleading.

Are your woofers in parallel or series or a mixture of both?

Hello, Atmasphere and Shadorne, thanks for your responses. Meters are good and useful I believe, just perhaps we should have better ones on our amps.
My woofer system is wired - parallel groups in series. There are 32 drivers in total. 8 forward facing and 8 rear facing per channel, each bank gets its own channel from one amp. This way one stereo amp drives the front 8 with the "left" channel and the rear bank is driven by the "right" channel. Each bank is then 4 ohm. So am I actually seeing double the power than on the meters? If the meter is reading 4 watts it is actually 8 watts, is that correct? I am using two 200 watt per channel amps.
Also FYI after really studying the meters since I wrote my original post the most I see is quite a bit more than 4 watts I originally cited, it is actually 18 watts. Going by Atmaspheres example of 4X and then doubling that, I need 144 watts to be safe. Guess I need to have my 200 watt amps. Though I could get away with 100 to 150 watt amps perhaps.
The interesting point also is just how small the excursion is at each driver, just a few millimeter at the most. The sound is also quite different due to this, ultimately giving great bass detail and no room shaking.

Atmasphere, I understand that you have/like Laverda motorcycles is that correct? I have a few and have ridden them since the early eighties.
Bob