Music levels for triamplification

[Glen Orr]

I have a tri-amplified system with electronic crossovers at 800 and 3500 Hz. At present, the bass amp is 80 watts, the midrange is 30 watts, and the tweeter is 10 watts. They are all class B amplifiers and I am designing class A amps for the midrange and tweeter.

Since the new amps are going to be class A, I obviously don't want them to be any larger than necessary (I'm a little cramped for space.) Four (4) watts should be more than adequate for the tweeter, but I'm not sure about the midrange. Some time ago, I saw published somewhere the relative average spectrum of speech and music, voltage (power) vs. frequency, that I could base my decision on, but I can't find it anywhere.

Can anyone help me? Thanks.

[ebrewste]

I have a similar system. I am using 15 Watts on all three channels. It goes as loud as my neighbors will stand. You will need to know your driver sensitivities. All three of mine are 91dB/W/m. I figure, just get the sensitivity of your diver (let's say 90dB) and start with 1 watt. For every 3dB double the power. So:

90dB - 1W
93dB - 2W
96dB - 4W
99dB - 8W
102dB - 16W
etc.

I think that is right. It sounds enough like that in my system that I never looked it up. I suppose all this is at 1m distance, but my head hurts after all this math, so I will ignore that.

members.home.net/ebrewste1

[ejrmathews]

I have read that there is significant risk in in triamping of having too much power available to the tweeters. Some even recommend staying with biamping to avoid the risk of blowing them with an unexpected transient. I am not sure how maximum power handling applies to tweeter specs and how this relates to amplifier power specs. Can anyone clarify this?

[gehlhoff]

Read the biamp article and maybe the active crossover project. I believe that is where I have seen the information you are looking for.

http://www.sound.au.com/

[gehlhoff]

Don't forget to account for differences in speaker efficiency double the wattage for every 3 db.

[Glen Orr]

My tweeters are rated at a maximum of 5 watts rms, which is much higher than you would expect to find in music program material. Many tweeters that are rated, let's say, 150 watts (meaning they can be used in a 150 system) would be fried instantly if you tried to put a 150 watt rms sine wave through it. Most of the power in music, and hence in that part of you music system, is in the lower frequencies.

All my speakers are very close in sensitivity.

I'll check out the website in Austrailia.... thanks.