is it normal for subwoofer magnet to get warm? played for about 30min with somewhat high bass and when i touched the cone it was warm so i removed it and checked the magnet it felt warm not that hot but really warm so i was woried since if the magnet was that warm how warm would the coil be.

 

Hi PP,
What is the power rating of the Woofer speaker.?
E

 

Some of the large speaker/ driver/ magnets I have used have heat sink fins to cool them off.
When things heat up the size changes and will not work the same.
"Warm" is not well defined but expected.

 

A speaker has a fairly low efficiency. Most power into it is turned into heat.
"High Bass" could be 20W or it could be 300W.

 

Adding to what AD A explained, the efficiency of a standard speaker [s very low, less than 10% for the best trumpet/horn speakers that sound really terrible for music. So playing at 100 watts will give you 90 watts of heat, and that will make a magnet quite warm after a while.

 

Speakers are "Impedance-Transformers",
and there is usually a hideous "Impedance-mismatch" between
the average "Direct-Radiator" type Speaker and the surrounding Air.
This is what causes the gross inefficiencies in most Speakers.
Inefficiency = Heat.

Properly designed Horns can easily have ~30% or better efficiency,
and are amongst the highest Fidelity Speakers available.
This is because they have a "better" "Impedance-Match" with the Air.

Most "high-end" Speakers have Horn-Loaded-Tweeters.
The only reason they don't have Horn-Loaded-Mid-Ranges as well
is because of physical size requirements for a properly designed Mid-Range-Horn.

A properly designed Horn must be at least 1-Wavelength long at the
lowest Frequency that it is expected to reproduce,
and,
the Circumference of the Horn-Mouth must also be at least 1-Wavelength at the lowest-Frequency.
( Rectangular-Mouth-Horns have a special formula for calculating the minimum dimensions ).
( If these rules are not followed,
the horn will "Honk" at certain Frequencies,
( yes, "Honk" the "official" term for what poorly designed Horns do ),
and they may possibly resonate at multiples of those Frequencies as well ).

Compromised-Designs, or "gimmick" Horns, can sometimes sound really, really bad.

The JBL-Corp. knows what they are doing,
and they've been doing it really well, for well over ~50-years,
and all of their big "Professional" Speakers have both
Horn-Loaded Mid-Ranges and Horn-Loaded Tweeters.
.
.
.

 

Obviously we are talking about different kinds of horn speakers. I am talking about those aluminum re-entrant trumpet speakers that are used for cheap PA systems in some businesses, that can not reproduce any frequency below 350 H or so, and then somebody wants to play violin music through them. It seems like LQC is thinking of those very large wooden corner speakers that provide a sound path quite a few feet long, and can actually reproduce below 60Hz. Two totally different animals, although the same principle .

 

The old Altec-Lansing Voice-of-the-Theater speakers used a horn midrange-tweeter, and a horn-loaded woofer for the high efficiency needed to provide sufficient sound volume for movie theaters with the relatively low-power, vacuum-tube amplifiers available at the time.

 

The old Altec-Lansing Voice-of-the-Theater speakers used a horn midrange-tweeter, and a horn-loaded woofer for the high efficiency needed to provide sufficient sound volume for movie theaters with the relatively low-power, vacuum-tube amplifiers available at the time.

NONE of those were the tinny sounding short and small trumpets that would fit into a 7 inch cube, and had a cutoff of about 400 Hz.