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Old 9th July 2019, 04:17 PM   #71
Brian Steele is offline Brian Steele  Grenada
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Originally Posted by ICG View Post
You can learn to recognize it by listening to it. It's not difficult.
Unless you're troubleshooting in a live bar with all of its background noise, at which point you'll be limited to identifying only gross abnormalities, like a blown driver. It's much easier to just run the measurement if it's a passive speaker, THEN pull the device for further testing if the measurement shows that something is a bit off. Active speakers are a whole other story.

And don't forget that the Enigma is a bandpass sub - what are bandpass subs best at? Filtering distortion produced by the driver. The story about users running bandpass subwoofers ragged and not knowing something was wrong until the driver actually stopped working is an often-repeated one.

Anyway, the process works for me, and that is what's important.
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Old 9th July 2019, 11:53 PM   #72
BP1Fanatic is offline BP1Fanatic  United States
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No need to at this point. However, if they end up blowing the driver again, I'll likely end up designing something entirely different for their use.

Oh, I passed by the bar this weekend. Not unexpectedly, and against my advice, they were using the background music system at top volume again, instead of using the main system. The Enigma (V2) is located below the bar counter (not the best location - but they're wired it up and everything BEFORE asking for my input, sigh), and the counter and floorboards were vibrating, LOL. The subwoofer survived that onslaught intact. I'm sure that they are going to be many more such incidents to come...
That's what we bassheads do!
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Old 9th July 2019, 11:57 PM   #73
BP1Fanatic is offline BP1Fanatic  United States
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And don't forget that the Enigma is a bandpass sub - what are bandpass subs best at? Filtering distortion produced by the driver.
That's why I am a BP Fanatic!
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Old 10th July 2019, 09:40 PM   #74
ICG is offline ICG  Germany
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Location: I had a Déjà Moo - I've seen that BS before!
Quote:
Originally Posted by Brian Steele View Post
Unless you're troubleshooting in a live bar with all of its background noise, at which point you'll be limited to identifying only gross abnormalities, like a blown driver. It's much easier to just run the measurement if it's a passive speaker, THEN pull the device for further testing if the measurement shows that something is a bit off.
You can't measure in a live bar with all of its background noise either because then it's in use.

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Originally Posted by Brian Steele View Post
And don't forget that the Enigma is a bandpass sub - what are bandpass subs best at? Filtering distortion produced by the driver. The story about users running bandpass subwoofers ragged and not knowing something was wrong until the driver actually stopped working is an often-repeated one.
It doesn't 'filter distortion', it filters higher frequencies and mechanical noise still comes out of the port. The story about users killing BP subs are often in the end ppl would have killed everything regardless of what principle the sub is based on. With wooden ears and enough abuse you can destroy everything.

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Anyway, the process works for me, and that is what's important.
Sure but that's not the only way to do it like you were implying, if you listen to the sub you can clearly hear where it's at its mechanical limit while it's playing and prevent the damage. And yes, you can hear that even at a BP - unless it's a single note one.
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Old 10th July 2019, 11:10 PM   #75
Brian Steele is offline Brian Steele  Grenada
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It doesn't 'filter distortion', it filters higher frequencies and mechanical noise still comes out of the port.
Hmm, so what else is distortion but what you just mentioned ?? Good grief man, are you trolling me or something?

Yes, *some* mechanical noise may make it out of the port - most of it however is filtered like basically everything else above the bandpass subwoofer's upper cutoff frequency, because the vented chamber acts as the LP filter - and ANY sound that originates in that chamber is subjected to that filter, including any distortion and mechanical noise generated by the driver. The Enigma is actually pretty good at doing just that, as is measured out of band noise is 15~20dB below its passband, when measured with a sine sweep. Even when driven to its 10% THD limit in its passband (which occurs around 40 Hz, and at 23.3V, the equivalent of 70W into 8 ohms (the driver's power rating, btw), measured distortion at higher bass frequencies (where most bass in music is found) is significantly lower. At 50 Hz it's just above 2% and above that it's around 1% or less. Good luck hearing that when playing sine waves, much less music . When playing most music, the only indicator that this sub is at its limits is that it just stops getting louder.
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Old 10th July 2019, 11:47 PM   #76
BP1Fanatic is offline BP1Fanatic  United States
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Hence why companies provide DSP with sealed and BR speakers. If a speaker moves, then it distorts. Bandpass moves less than direct radiator.
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Old 11th July 2019, 12:20 AM   #77
Brian Steele is offline Brian Steele  Grenada
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Hence why companies provide DSP with sealed and BR speakers. If a speaker moves, then it distorts. Bandpass moves less than direct radiator.
DSP can be useful for bandpass systems as well. e.g. 4th order bandpass systems can be excursion limited near their cutoff frequency, so some dynamic eq or limiting around that frequency can produce good results. Also, at the resonance frequencies, it might be a good idea to limit any sustained power at that those frequencies because the driver's coil is basically stationery at that point. And there's also the question of the out of band noise that needs to be dealt with. The Enigma build has a low out of band noise level, but other bandpass designs could end up suffering badly from it.

I did some distortion measurements for my brother's KSubs, for example, and I'm pretty sure some form of filtering is built in to the amplifiers. The distortion profile suggests that at least there's some HP filtering going on, and it *might* be level-dependent (distortion at frequencies below its passband reduces as volume increases). The distortion profile of the KSubs is worse than the Enigma at anything up to the Enigma's peak output level BTW, but that might be a side-effect of years of abuse . I haven't really had a chance to pull one of them completely apart to take a closer look.
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Old 11th July 2019, 01:29 AM   #78
Patrick Bateman is offline Patrick Bateman  United States
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It's too bad they don't have more room. I've never built a triple reflex, but the sims seem to indicate that you can do some bizarre alignments with it. For instance, you can get them to play well under 20hz with small woofers. Or you can also use a triple reflex to get the efficiency very high, much higher than you can get with a single reflex.

On the downside, they're probably one of the most complex subwoofer enclosures
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Old 11th July 2019, 04:15 AM   #79
Brian Steele is offline Brian Steele  Grenada
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On the downside, they're probably one of the most complex subwoofer enclosures
That's usually the plan killer for me. I've looked at some pretty exotic designs to generate bass, but always end up applying the KISS principle.
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Old 11th July 2019, 05:43 PM   #80
BP1Fanatic is offline BP1Fanatic  United States
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Technically, a BR, BP4, BP6, and TH could all be a 7 board enclosure not including bracing.
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