Speakers need warm up?

[JMFahey]

if we are going to be serious about this...
as copper heats up the resistance goes up. this will change booth the impedance of the transducer and how the crossover its connected to behaves.

Yes, resistance, specially the voice coil one, changes a lot, because temperatura changes a lot.
Then efficiency/sensitivity, damping, TS parameters, change a lot and that is audible.
The first change and most noticeable is calles "power compression" and can make a speaker easily lose 3dB sensitivity ... which for a speaker is a lot.

so assuming for a moment there is a significant change in temperature of the transducers coil, lets say in the order of 10 degrees c or more, then, there is a true effect. what the effect is is greatly dependent on what the circuit looks like its connected to and how the resistance change effects its response curve.

Yes, but temperatire rise is even way higher if speaker is played LOUD.
Easily from reaching 90C to over 200C for some PA speakers (or Musical Instrument or Disk Jockey ones).
These voice coils reached some 200C (the still whole one) to over 260C (the multi split one):

An externally hosted image should be here but it was not working when we last tested it.

if the temperature is then transferred to the magnetic core, the resulting temperature increase also effects the the magnetic flux density of the magnet. this therefor will decrease the efficiency of a transducer as the temperature of the magnet increases.

Although the thermal magnetization effect exists (Curie point) here we don´t reach that high (we are talking 400C and higher *magnet* temperatures) but hot voice coils have a lot to say about sound performance.

likewise is true for the components in a crossover, but to a lesser extent as typically the resistance and capacitive comments are relatively temperature stable, the copper in the coils though will change resistance with temperature.

An inadequate wire diameter used for a low pass coil in series with a powerful woofer will heat up, no doubt; all other coils won´t handle much power so variation should be very small.

also since the wire leading to the speaker is seen electrically as a resistor, and current is pulled though the wire the wire heats up and increases the resistance. this will also effect overall impedance and the phase angle of the impedance seen by the amplifier at any given frequency, so you will be at the mercy of how that impedance change is handled by the amplifier..

same as above.

the problem here is that none of the current flows are constant in an audio system and therefor the temperatures are not stable. response curve changes would be dynamic not static

yes, but time constants involved are large, so system will verage dissipated power turned into heat.

unless the items are externally heated or cooled to make the temperature's stable and therefore the impedances and flux densities consistent.

Not done on regular Audio equipment, only on very unusual equipment such as VERY high power electromechanical actuators (think KW or even Horse Power ratings) used to, say, flex airplane wings up and down to check for metal fatigue cracks.
And somebody once made a large PA speaker where you injected compressed air around the Voice Coil to cool it, but it was too complex for practical use.

Some speakers use finned heatsinks bolted to the magnets and at least Electro Voice gave 2 different power ratings for the same speaker, depending on whether the cabinet was closed or open.

 

[scottjoplin]

Okay guys. What I was suggesting was a way to see if it was the speaker or your ears/brain that was changing. If the first thing you hear is a while into operation, if it is the speaker that is changing, it is hopefully done by the time you return, and successive plays will sound the same.
If it is your brain/ears you will notice the same change as going into however long from cold.

It's not well-controlled, but we may get a clue about one particular speaker/listener set.

That's pretty much what I thought you meant, makes sense, thanks for the clarification

 

[Panelhead]

One type in particular

I am currently using a conventional sealed box 3 way. If the sound “warms” up it is a very small change. When I used amps with Big transmission type triodes the sound changed during the first 30 minutes or so with every speaker.
But I ran Lowthers in a TQWT cabinet for about 10 years. If the drivers had not been used for a few months the sound was dead for about an hour. I had multiple drivers and changed them out from time to time. They always sounded lifeless if unused. Once played for a while the sound improved dramatically.
I suspected it was the surrounds but may have been something in the voice coil or magnetic gap.
These had speaker wire coming in and connecting directly to the driver. No crossover, no binding posts, no internal wire.
I suspect my current speakers with those three items may exhibit some change in driver response if sitting for a while. But the crossovers, binding posts, and internal wiring color the sound enough to hide the change in driver response.

 

[scoobis]

@JMFahey

to ther original point, is the effect plausible. and i believe the answer is yes, and every part plays a small role in the change.

but as far as actually doing something about it, ... don't make me go back to my suggested manufacturing techniques lol .. though might make for one visiting the manufacturing floor often quire enjoyable.

 

[scoobis]

I am currently using a conventional sealed box 3 way. If the sound “warms” up it is a very small change. When I used amps with Big transmission type triodes the sound changed during the first 30 minutes or so with every speaker.
But I ran Lowthers in a TQWT cabinet for about 10 years. If the drivers had not been used for a few months the sound was dead for about an hour. I had multiple drivers and changed them out from time to time. They always sounded lifeless if unused. Once played for a while the sound improved dramatically.
I suspected it was the surrounds but may have been something in the voice coil or magnetic gap.
These had speaker wire coming in and connecting directly to the driver. No crossover, no binding posts, no internal wire.
I suspect my current speakers with those three items may exhibit some change in driver response if sitting for a while. But the crossovers, binding posts, and internal wiring color the sound enough to hide the change in driver response.

how are you measuring the response?