Blew out the woofers on my brand new speakers, need help to find the cause

[ta240]

Ported (and active) subwoofers normally have this feature. Active speakers will also typically have that and/or active limiters to prevent you from frying the drivers unless you REALLY try.

Passive speakers typically do not have high pass filters. A 10 second continuous sine wave below the port tuning is a very different scenario than normal music, and is what I would consider an active attempt to ruin the drivers. The driver will flap around uncontrollably, bottoming out, possibly tearing the suspension. To even be able to hear a 30hz (not to mention 20hz) sine wave from a speaker like that is a pretty safe sign you're playing way too loud.

Excellent point. With a -6db of 48Hz to hear a tone as low as was being played back the speaker and amp were working incredibly hard.

I believe that if manufacturers don't implement a high pass filter, then I'm not responsible if the woofer smokes with 20 Hz signal, because not all audio devices have one.

I would prefer that manufactures didn't add more passive filters just to prevent people from destroying the speakers doing something they were never intended to do. A 20Hz signal as part of music would: not last as long as a test tone and not even be audible at most listening levels.
I'm guessing the volume level and power that it required to make a decently loud 20Hz sound out of those speakers would have created a deafening 1000Hz sound. That is the 'safety' feature that audio devices have to warn you that the amp output it too high...... when playing music.

 

[rdenney]

would this be a safe method to find out the limits of a subwoofer....provided a slow increase of volume?

I would think so in most cases. My own rule of thumb: If it sounds bad, TURN IT DOWN!

Note that most subwoofers present quite a bit of harmonic distortion at low frequencies, however. But harmonic distortion might actually be a good thing in smallish measure for tones in the 20Hz range, simply because that distortion makes them hearable in the first place. With a series of overtones spaced at the fundamental frequency, those overtones set up a difference tone in our hearing that still implies the root tone. So, a 20Hz signal in a subwoofer with 10% distortion (-20 dB relative to the signal) might have overtones at 40Hz, 60Hz, and 80Hz that are audibly loud. Our ears will see that 20Hz spacing between those overtones and interpret the sound as 20Hz. A 40Hz sound won't have the 60Hz overtone, and won't read to the listener as 20Hz.

Tuba players deal with this all the time. A "pedal" Bb, at 28 Hz, is the fundamental frequency of the open bugle of a Bb contrabass tuba (e.g., your typical wind-band tuba or sousaphone). No tuba player has the lungs to play a 28Hz sine wave loudly enough to be heard over other musicians, even if the tuba and embouchure could produce it. But that tone on a tuba may have far more than 10% harmonic distortion--it may be more like 200% where the overtones are, in total, 10 dB louder than the fundamental tone. Here's an FFT spectrogram of me playing a low Bb (58Hz) that I've shown here before:

(Yes, I did this at least 20 years ago.)

The third, fourth, and sixth harmonics are all louder than the fundamental. But people don't hear it as higher notes, they hear it as 58 Hz, because those overtones are all spaced at 58Hz intervals. The same thing occurs with flutes and (especially) diapason pipes on organs, even without adding stops to specifically add more upper overtones.

So, a sub with (barely) audible overtones is certainly not going to be adding what is not already there in any actual music.

When a tuba player or the instrument runs out of power (that is, sufficient air flow to sustain a pleasing mix of overtones in the vibration of the lips), lots of much higher overtones and untuned harmonics (aka, noise) get added to the sound, creating what tubas players call "edge". Edge is what makes a loud note read as loud, but tuba players minimize it as much as possible (for classical music) compared with other brass instruments. Too much edge sounds bad to anyone. A bass trombone playing that 58Hz Bb at real volume has, in the words of one noted physicist and tuba player, the harmonic characteristics of a hammer on a frying pan.

A loudspeaker that produces "edge" on low frequencies when playing too loudly is soon to depart this world (added to bring this sidebar back to topic).

Rick "occasionally plays stuff very loud" Denney

 

[Deleted member 48726]

I'm serious. There are thousands of DACs and amps without HPF.

Just don't run test tones in uncontrolled fashion and you are fine. When listening to music you are also fine. If you push the speaker when listening to music, you'll hear distortion and mechanical noises before the smoke appears.

 

[Mnyb]

I would think so in most cases. My own rule of thumb: If it sounds bad, TURN IT DOWN!

Note that most subwoofers present quite a bit of harmonic distortion at low frequencies, however. But harmonic distortion might actually be a good thing in smallish measure for tones in the 20Hz range, simply because that distortion makes them hearable in the first place. With a series of overtones spaced at the fundamental frequency, those overtones set up a difference tone in our hearing that still implies the root tone. So, a 20Hz signal in a subwoofer with 10% distortion (-20 dB relative to the signal) might have overtones at 40Hz, 60Hz, and 80Hz that are audibly loud. Our ears will see that 20Hz spacing between those overtones and interpret the sound as 20Hz. A 40Hz sound won't have the 60Hz overtone, and won't read to the listener as 20Hz.

Tuba players deal with this all the time. A "pedal" Bb, at 28 Hz, is the fundamental frequency of the open bugle of a Bb contrabass tuba (e.g., your typical wind-band tuba or sousaphone). No tuba player has the lungs to play a 28Hz sine wave loudly enough to be heard over other musicians, even if the tuba and embouchure could produce it. But that tone on a tuba may have far more than 10% harmonic distortion--it may be more like 200% where the overtones are, in total, 10 dB louder than the fundamental tone. Here's an FFT spectrogram of me playing a low Bb (58Hz) that I've shown here before:

(Yes, I did this at least 20 years ago.)

The third, fourth, and sixth harmonics are all louder than the fundamental. But people don't hear it as higher notes, they hear it as 58 Hz, because those overtones are all spaced at 58Hz intervals. The same thing occurs with flutes and (especially) diapason pipes on organs, even without adding stops to specifically add more upper overtones.

So, a sub with (barely) audible overtones is certainly not going to be adding what is not already there in any actual music.

When a tuba player or the instrument runs out of power (that is, sufficient air flow to sustain a pleasing mix of overtones in the vibration of the lips), lots of much higher overtones and untuned harmonics (aka, noise) get added to the sound, creating what tubas players call "edge". Edge is what makes a loud note read as loud, but tuba players minimize it as much as possible (for classical music) compared with other brass instruments. Too much edge sounds bad to anyone. A bass trombone playing that 58Hz Bb at real volume has, in the words of one noted physicist and tuba player, the harmonic characteristics of a hammer on a frying pan.

A loudspeaker that produces "edge" on low frequencies when playing too loudly is soon to depart this world (added to bring this sidebar back to topic).

Rick "occasionally plays stuff very loud" Denney

This is true for many bass instruments the overtones are larger than the fundamental note , which make the instrument possible to hear . You rather feel the fundamental if it’s loud .

 

[Mnyb]

Btw for reference.
The loudness curves aka equal loudness contour aka Fletcher Munson curves.
You be playing very loud to hear a pure 20Hz tone.

Equal-loudness contour - Wikipedia

en.m.wikipedia.org

 

[JLGF1]

if (smoke-involved)
then (yes);

 

[dualazmak]

Sorry to be a little bit out of the scope of this thread, but,,,

The more sophisticated/complex our audio system would be, the more/higher "safety measures" should be implemented and strictly performed, I believe.

EDIT: My intention of this post is that at least one or two of the following precautions would be hopefully somewhat worthwhile in your audio system; please understand that I am not intending to force/recommend all of them for you.

Just for your possible reference, and if you would be interested, please refer to my latest system setup as of August 3 2023, also please refer to my latest "startup/ignition sequences" and "shutdown sequences".

- Very careful "startup/ignition sequences" and "shutdown sequences" should be, have been, standardized and strictly performed (ref. here).

- In upstream DSP, I have high-pass (low-cut) filter at 15 Hz for the large-heavy active subwoofers (even it has own safety mechanism/circuit), and at 45 Hz for woofers.

- In upstream DSP, I have sharp (- 45 dB/Oct) low-pass (high-cut) filters at 25 kHz to shutdown/cut-off possible high-gain UHF noises for midrange-squawkers, tweeters, and super-tweeters (ref. here).

- I have high-pass (low-cut) 68 microF protection capacitor for midrange-squawkers, 10 microF protection capacitors for tweeters and supertweeters (of course, Fq responses "before and after" the protection caps were intensively measured/checked; ref. here and here).

- Total (whole sum) digital-line level signal and each of the amplifiers' SP high level outputs are always monitored by DIY large-glass-face IEC 60268-17 compatible 12-VU-Meter Array (ref. here).

- Any of test (tone) signals and/or reference music tracks should be played at first time with master volume/gain less than -30 dB or even lower.

- In some specific/special occasions (including the burn-in of amplifiers), I play test signals and/or reference music in complete silence by using 8 Ohm 100 Watt dummy speakers (resistors) (ref. here).

EDIT:
- Also, I always have been sticking to "All-in-ASIO" digital signal routing partly due to safety concerns (ref. here and here).

 

[antcollinet]

Sorry to be a little bit out of the scope of this thread, but,,,

The more sophisticated/complex our audio system would be, the more/higher "safety measures" should be implemented and strictly performed, I believe.

Just for your possible reference, and if you would be interested, please refer to my latest system setup as of August 3 2023, also please refer to my latest "startup/ignition sequences" and "shutdown sequences".

- Very careful "startup/ignition sequences" and "shutdown sequences" should be, have been, standardized and strictly performed (ref. here).

- In upstream DSP, I have high-pass (low-cut) filter at 15 Hz for the large-heavy active subwoofers (even it has own safety mechanism/circuit), and at 45 Hz for woofers.

- In upstream DSP, I have sharp (- 45 dB/Oct) low-pass (high-cut) filters at 25 kHz to shutdown/cut-off possible high-gain UHF noises for midrange-squawkers, tweeters, and super-tweeters (ref. here).

- I have high-pass (low-cut) 68 microF protection capacitor for midrange-squawkers, 10 microF protection capacitors for tweeters and supertweeters (of course, Fq responses "before and after" the protection caps were intensively measured/checked; ref. here and here).

- Total (whole sum) digital-line level signal and each of the amplifiers' SP high level outputs are always monitored by DIY large-glass-face IEC 60268-17 compatible 12-VU-Meter Array (ref. here).

- Any of test (tone) signals and/or reference music tracks should be played at first time with master volume/gain less than -30 dB or even lower.

- In some specific/special occasions (including the burn-in of amplifiers), I play test signals and/or reference music in complete silence by using 8 Ohm 100 Watt dummy speakers (resistors) (ref. here).

Yeah, but (and I say this in the nicest way ) you are a bit of an outlier.

I doubt (1% of) 1% of 1% of home audio systems have this level of protection implemented. In fact I doubt (1% of) 1% of 1% even have a wiring diagram created of the system like the one those that you have created.




EDIT - I've just looked in more detail at your post linked above. I'm adding an extra "1% of"

 

[Deleted member 48726]

Yeah, but (and I say this in the nicest way ) you are a bit of an outlier.

I doubt (1% of) 1% of 1% of home audio systems have this level of protection implemented. In fact I doubt (1% of) 1% of 1% even have a wiring diagram created of the system like the one those that you have created.




EDIT - I've just looked in more detail at your post linked above. I'm adding an extra "1% of"

We all know @dualazmak is representing the majority of audiophiles..

 

[Prana Ferox]

If a passive loudspeaker is not designed for low frequencies, why don't manufacturers implement a high pass filter for the woofers in the crossover, like the Arendal 1961?
Why should I be obligated into using Bass Management, if I prefer to send only the LFE channel to a subwoofer?

I believe that if manufacturers don't implement a high pass filter, then I'm not responsible if the woofer smokes with 20 Hz signal, because not all audio devices have one.

Implementing a passive speaker-level high-pass filter at the low frequencies relevant here tends to require large and expensive components, it's not really practical. This is also why crossovers to subs are almost always done line level (before the power amplifier) and usually digitally.

Also, as stressed in this thread, a) frequencies this low at meaningful magnitude are extremely rare in actual music content and uncommon even in SFX-laden movies, and b) most speakers sound distressed long before the physical damage point, to where a sober listener would turn them down. So it usually takes a kind of special mix of conditions to destroy a speaker, which the OP managed to get into perfectly

There are various things you can do as a speaker designer to provide protection against over-excursion, such as going sealed vs ported, selection of port tuning frequency, sizing the cabinet below optimal, etc but each of these can affect bass in the regions people do care about for music, so it's all a compromise.

 

[Sokel]

Implementing a passive speaker-level high-pass filter at the low frequencies relevant here tends to require large and expensive components, it's not really practical. This is also why crossovers to subs are almost always done line level (before the power amplifier) and usually digitally.

Also, as stressed in this thread, a) frequencies this low at meaningful magnitude are extremely rare in actual music content and uncommon even in SFX-laden movies, and b) most speakers sound distressed long before the physical damage point, to where a sober listener would turn them down. So it usually takes a kind of special mix of conditions to destroy a speaker, which the OP managed to get into perfectly

There are various things you can do as a speaker designer to provide protection against over-excursion, such as going sealed vs ported, selection of port tuning frequency, sizing the cabinet below optimal, etc but each of these can affect bass in the regions people do care about for music, so it's all a compromise.

Pro audio bass drivers almost always suggest a hi-pass down there but almost never is implemented as most of the pro audio amps for bass have a line level subsonic filter option.
So...

 

[Deleted member 48726]

Pro audio bass drivers almost always suggest a hi-pass down there but almost never is implemented as most of the pro audio amps for bass have a line level subsonic filter option.
So...

Most pro settings also deal with a whole different level of voltage and power than the typical living room situation. And pro meaning that you get money to keep the music playing. Problematic if voicecoils burn up or amps starts smoking.

 

[dualazmak]

Yeah, but (and I say this in the nicest way ) you are a bit of an outlier.

I doubt (1% of) 1% of 1% of home audio systems have this level of protection implemented. In fact I doubt (1% of) 1% of 1% even have a wiring diagram created of the system like the one those that you have created.

Yes, I assume you are almost right regarding the statistics of population in our ASR community...

Nevertheless, at least one or two of my safety precautions in my above post #47 would be of reference and worthwhile for everybody visiting this thread, I just hope; that is my honest intention of the post #47. Of course, you are free to ignore all of them....

 

[dasdoing]

I guess home users are just not expected to play loud music.
Even if music with much energy below 40Hz is realitvly rare, it does exist.
would this speaker survive a playlist of these tracks at "reference level"? https://www.audiosciencereview.com/forum/index.php?threads/bass.18999/

 

[Sokel]

Most pro settings also deal with a whole different level of voltage and power than the typical living room situation. And pro meaning that you get money to keep the music playing. Problematic if voicecoils burn up or amps starts smoking.

Fun fact,once in a small club where mostly amateurs play when the bass rig went down bass player got a mic and was going "bommp,bommp,bommp".
He got the applause of his life.

 

[Deleted member 48726]

Fun fact,once in a small club where mostly amateurs play when the bass rig went down bass player got a mic and was going "bommp,bommp,bommp".
He got the applause of his life.

Ha! Yeah easy job in a back to the 90's dance event. Just go uhn-tis uhn-tis uhn-tis.

 

[antcollinet]

I guess home users are just not expected to play loud music.
Even if music with much energy below 40Hz is realitvly rare, it does exist.
would this speaker survive a playlist of these tracks at "reference level"? https://www.audiosciencereview.com/forum/index.php?threads/bass.18999/

Probably, depending on listening distance. At 1m then reference level is peaks of about 40W, and average <1W

That goes to 1.6 and 160W at 2m

Reference at 3m probably becomes marginal if we ignore room gain.

 

[dualazmak]

Even if music with much energy below 40Hz is realitvly rare, it does exist.

Yes, fully agree. I, at least myself, need to go down fairly near to 15 Hz "music" sound; e.g. as I shared here showing the 3D sound spectrum of Adobe Audition 3.0.1. Also around 33 Hz in many cases e.g. as shared here and here.

would this speaker survive a playlist of these tracks at "reference level"? https://www.audiosciencereview.com/forum/index.php?threads/bass.18999/

I always follow that thread "BASS!" very very carefully; some of the tracks shared there are really dangerous and harmful, I believe.

 

[dualazmak]

We all know @dualazmak is representing the majority of audiophiles..

Spoiler: Please just ignore the content under this Spoiler cover!

Even though I appreciate and accept your kind (joke?) message, according to the above post #48 by @antcollinet, it looks I am representing the very rare species of audiophile.

 

[Deleted member 48726]

Spoiler: Please just ignore the content under this Spoiler cover!

Even though I appreciate and accept your kind (joke?) message, according to the above post #48 by @antcollinet, it looks I am representing the very rare species of audiophile.

You are. But in a good way from where we can learn and you are always willing to share your experiences and you do it in a calm and polite way.