amp hiss impact on speakers

IMHO, this would lead over some extensive time to a premature aging of the part.

Hi Davey,

It seems to me to be self-evident that there must be **some** power level, other than zero, below which continuous application of that power to a tweeter will not significantly affect its longevity. Assuming, of course, that the frequency content of that power is within the tweeter’s rated bandwidth.

Based on the assumption I stated earlier, that the hiss level the OP described corresponds to an SPL of 40 db at 1 meter (and I would feel pretty certain that the actual number is much less than that), and based on the specified parameters for the tweeter I used as an example (which is used in a small stand-mounted speaker), it would mean that the tweeter is being driven by one five-millionth of its rated power handling capability.

Given the assumption that there is **some** power level, other than zero, below which continuous application to a tweeter will not significantly affect its longevity, it seems to me to be a very safe assumption that one five-millionth of rated power handling capability is small enough. And again, the actual number in this case is probably much less than that.

Regards,
-- Al

Tweeters are usually specified as being able to handle many watts, within their specified frequency range. For example consider this datasheet for a tweeter that is used in a very small stand-mounted speaker made by Salk (model WOW1). The datasheet indicates that the tweeter is rated to be able to handle 100 watts when used with an appropriate crossover network that would keep low frequencies out of it.

Since you only hear the hiss when your ear is very close to your speakers it would seem safe to assume that at the usual 1 meter measuring distance the hiss level is **well under** say 40 db. But let’s assume it is 40 db. Given a tweeter sensitivity in the area of say 87 db/1 watt/1 meter, which is the spec on the tweeter I linked to, it can be calculated that the tweeter is producing the hiss in response to an input in the rough vicinity of one fifty-thousandth of a watt, i.e., 0.00002 watts!

The bottom line: It’s a non-issue.

Regards,
-- Al