Are electronics inside a loudspeaker sensitive for the airpressure, and can it measure worse because of that ?

[Tangband]

I have some questions that some of you might be able to answer.
This might be an issue or not - lets find out .

Is there any disadvantage to put a dsp crossover and amplifier inside a loudspeaker , because of the airpressure and high sound spl inside the loudspeaker ?

Will the electronics measure worse because of this ?

How are the reability in long term use ?

A feeling I have is that some subwoofers break down after 3-5 years, and I wonder If thats because of the airpressure inside the box is destroying the electronics, or is it just bad quality electronics in some subwoofers ?

Is it done any investigations regarding this ?

Some capacitors are slightly microphonic - does this matter ?

What about other electronics inside the speaker, like IC:s and microchips ? Is the SINAD lowered from the electronics if theres a high sound level inside the speakerbox ?

 

[Speedskater]

Any well designed active DSP crossover using modern parts should not be sensitive to air pressure, spl or vibration at the levels found inside a loudspeaker cabinet.
Legacy and boutique capacitors are a different story.

 

[Katji]

A feeling I have is that some subwoofers break down after 3-5 years, and I wonder If thats because of the airpressure inside the box is destroying the electronics, or is it just bad quality electronics in some subwoofers ?

Yes, but so far i know it's the amplifiers that fail...but they are enclosed in steel cases...so people say it's because of higher heat there, but decent/not cheap car amps don't fail so much...so therefore the problem [in the subwoofers] is the super-cheap low quality amps they use.
You don't hear of it with expensive subs like B&W. they get sold and re-sold on forums for like >10 years.

 

[Tangband]

How about SINAD and quality - is this compromised in the dsp crossovers and amplifiers in a loudspeaker box with spl:s of 100-105 dB inside ?
Has someone made measurements about this ?

 

[Speedskater]

It might be tricky to do SINAD and quality measurements. Those measurements should be made across the driver voice coil. Using a test microphone will tell you much more about the drivers than the electronics.

 

[Katji]

Not necessary, there cannot be such an effect. SINAD depends on noise and distortion...and that depends on circuit design and shielding and so on.
DSP crossovers used in the highest SQ speakers now. Passive crossovers will quite soon become obsolete and extinct. If vibration would be a probem, it would be a problem of system design, i.e. isolation/shielding.

 

[Tangband]

Not necessary, there cannot be such an effect. SINAD depends on noise and distortion...and that depends on circuit design and shielding and so on.
DSP crossovers used in the highest SQ speakers now. Passive crossovers will quite soon become obsolete and extinct. If vibration would be a probem, it would be a problem of system design, i.e. isolation/shielding.

…So there is no need to have a back box for a closed box subwoofer amplifier protecting it, because of the airpressure inside of the box ?

 

[FeddyLost]

So there is no need to have a back box for a closed box subwoofer amplifier protecting it, because of the airpressure inside of the box ?

If you don't have correct requirements about temperature range and vibration inside your DIY sealed box, I'd keep any unknown amplifier outside.
Typical efficiency of subwoofer driver is few percent, so at least 9/10 of applied power will stay inside. Without special measures it can significantly shorten life of an amp.

 

[Tangband]

If you don't have correct requirements about temperature range and vibration inside your DIY sealed box, I'd keep any unknown amplifier outside.
Typical efficiency of subwoofer driver is few percent, so at least 9/10 of applied power will stay inside. Without special measures it can significantly shorten life of an amp.

If this is true one shouldnt buy plateamps without backbox in a sealed suwoofer ?

 

[FeddyLost]

If this is true one shouldnt buy plateamps without backbox in a sealed suwoofer ?

I mean that at least at design stage you need to understand real situation about environment inside the box.
For example, pro subwoofers at good volume in vented enclosure literally pump hot air from bass reflex ports.
If you want to be on safe side or sell your sealed subs for end-users, you really need to calculate use cases or stress test your equipment with plate amps. Or make separate box ...

 

[KSTR]

Air pressure itself is not a problem for electronics, but vibration can be, structurally induced or excited by air pressure gradients.
Some capacitor types are vibration-sensitive to varying degrees (and some are even prone to crack and severly degrade under excessive vibration), as are crystals and crystal oscillators, voltage references and some other precision parts. With a bit of care in PCB layout, mounting style and general construction any sensitivity to vibration can be reduced to irrelevant levels even under harsh conditions (on-the-road/PA use), all of which increases ruggedness and long-time reliability.

But basically there is not much to worry about unless you run into cheaply designed and built stuff.

 

[Sokel]

That's an example of how the manufactures see it:

 

[Tangband]

Air pressure itself is not a problem for electronics, but vibration can be, structurally induced or excited by air pressure gradients.
Some capacitor types are vibration-sensitive to varying degrees (and some are even prone to crack and severly degrade under excessive vibration), as are crystals and crystal oscillators, voltage references and some other precision parts. With a bit of care in PCB layout, mounting style and general construction any sensitivity to vibration can be reduced to irrelevant levels even under harsh conditions (on-the-road/PA use), all of which increases ruggedness and long-time reliability.

But basically there is not much to worry about unless you run into cheaply designed and built stuff.

Interesting .
Regarding crystal oscillators - Maybe its not a good idea then to have a dac inbuilt inside the speaker ? Or is this a non problem ?

 

[Vacceo]

My subwoofers are around 15 years old, I use them daily and they still work quite well, so durability wise, either they are built like tanks or I got lucky...

At any rate, this thread is quite interesting and it may allow some of us (me at least!) to learn a thing or two. So let´s ask @amirm some technicalities.

I have re-watched a couple reviews on active speakers posted on the forum. Among the data provided we can check distortion, but not noise. This type of speakers include several amps, hence we can assume that there will be noise and distortion, but as usual, the key is knowing how much and if audible. Distortion is covered in the graphs but what about noise? Is it relevant in the particular case of active speakers?

And last but not least: if we hook up an active speaker to a source like an AVP that does not measure too well (let´s say a Marantz AVP reviewed over here), will the noise and distoritio of the device transfer and add up to the one inherent on the speaker? How does that transfer work? Does it sum or multiply?

 

[KSTR]

Interesting .
Regarding crystal oscillators - Maybe its not a good idea then to have a dac inbuilt inside the speaker ? Or is this a non problem ?

As always, the answer is "it depends", I fear. A minority of products might actually show significant (potentially audible) vibration artifacts when measured very explicitly for this, but that's just me guessing.