Dude explains how active speakers work

[jhaider]

He's lying or just a buffoon.

That’s not fair or accurate!!!






You need to change the “or” to “and.”

 

[fpitas]

No it won’t. The tweeter is not going to emit a 50/60Hz or 100/120Hz hum. It will therefore not affect the polar pattern. The contention here is that a low frequency signal of sufficient amplitude will affect the tweeter’s ability to reproduce high frequencies with low distortion. Whether or not that is true would depend on the driver. In any case, the simple answer is: don’t use amps that hum in active speakers! Or anywhere for that matter.

I'm not sure why you addressed me. Kongwee contends that everything reaches the tweeter, including the midrange. It's a dumb argument and I'm going to stop discussing it.

 

[theREALdotnet]

I'm not sure why you addressed me. Kongwee contends that everything reaches the tweeter, including the midrange. It's a dumb argument and I'm going to stop discussing it.

I did not address you. I quoted your statement and disputed it. I don’t care about your tussles or historical arguments with other ASR members.

 

[fpitas]

I did not address you. I quoted your statement and disputed it. I don’t care about your tussles or historical arguments with other ASR members.

Uh huh

 

[theREALdotnet]

Uh huh

Not sure what you mean. When I got my education, science and engineering wasn’t about who said what, or who likes/hates whom, it was simply follow the evidence, be guided by the facts.

Back on topic, your assertion that low frequency artifacts ending up at the tweeter would show up in the polar radiation pattern of the speaker is not true. The tweeter would be unable to emit them at the required SPL. However, sending those low frequency artifacts to the tweeter may or may not affect its ability to produce clean HF output. This I believe was GR’s argument, for which I haven’t seen any evidence (I think a distortion plot would tell the story), but it certainly shouldn’t be dismissed purely because Danny‘s been talking a lot of nonsense in the past.

 

[fpitas]

Not sure what you mean. When I got my education, science and engineering wasn’t about who said what, or who likes/hates whom, it was simply follow the evidence, be guided by the facts.

Back on topic, your assertion that low frequency artifacts ending up at the tweeter would show up in the polar radiation pattern of the speaker is not true. The tweeter would be unable to emit them at the required SPL. However, sending those low frequency artifacts to the tweeter may or may not affect its ability to produce clean HF output. This I believe was GR’s argument, for which I haven’t seen any evidence (I think a distortion plot would tell the story), but it certainly shouldn’t be dismissed purely because Danny‘s been talking a lot of nonsense in the past.

I'm ignoring you because you're misattributing me. I don't know if you're trolling, or what.

Here's a rabbit with a pancake on its head.

 

[TheBatsEar]

However, sending those low frequency artifacts to the tweeter may or may not affect its ability to produce clean HF output. This I believe was GR’s argument, for which I haven’t seen any evidence (I think a distortion plot would tell the story), but it certainly shouldn’t be dismissed purely because Danny‘s been talking a lot of nonsense in the past.

I think that is what Danny thinks, yes.
To which i said, even in an active speaker, one would certainly protect a tweeter from all that low frequency nonsense with a capacitor.

Engineer, thinking about LF artifacts, 1974, colorized.

If there is no such capacitor it means the engineer was confident that either there aren't any LF artifacts in the first place, or they don't matter.

 

[Ken Tajalli]

Back on topic, your assertion that low frequency artifacts ending up at the tweeter would show up in the polar radiation pattern of the speaker is not true. The tweeter would be unable to emit them at the required SPL. However, sending those low frequency artifacts to the tweeter may or may not affect its ability to produce clean HF output. This I believe was GR’s argument, for which I haven’t seen any evidence (I think a distortion plot would tell the story), but it certainly shouldn’t be dismissed purely because Danny‘s been talking a lot of nonsense in the past.

This is what I think:
We have two scenarios 1- passive implementation 2- Active
Danny (is that his name?) is arguing against Active, in favour of a dual amp, split passive crossover (did I get that right?)
A second order (most common) passive crossover for tweeters, does pass some low frequency to the driver too, and from top of my head it is going to be far more than any residual hum a power amp may produce.
Distortion, what distortion? if an active filter is used before amplification to the tweeter, how could the output have distortions at frequencies that are not in the signal, or have been reduced.
Even at crossover frequencies, the bass driver may be fed some distortion patterns which are above the xover freq., however, the bass driver would naturally not be able to radiate them all that much. Remember, first artefact is at twice the frequency @ -70-90 dB (approx). The tweeter would not have any artefacts below the Xover frequency, bar what the filter lets through. How is that any different from passive implementation?! His argument is not valid.
As another member correctly has already mentioned, just don't use crap amps! with lots of hum and distortion.
Besides, in active mode, it is far far easier to implement complex filters, even 48dB/octave ones accurately.
And connecting the output of the amp directly to voice coil, means much better damping, efficiency, phase accuracy.
Overall, he is trying to sell something, his arguments are "way down here" , his commercial interest are "right up there" ( as he demonstrates with his hands )

 

[Ken Tajalli]

If there is no such capacitor it means the engineer was confident that either there aren't any LF artifacts in the first place, or they don't matter.

I never used a capacitor, in 30 years I have not blown a tweeter.
Using a capacitor messes with the whole idea of precise frequency and phase control.

 

[abdo123]

Same for the woofer

What?

a big Woofer can defintely produce high frequencies at high volumes. it's just not as linear and the directivity is really high.

 

[fpitas]

I never used a capacitor, in 30 years I have not blown a tweeter.
Using a capacitor messes with the whole idea of precise frequency and phase control.

Some amps have huge turn-on and turn-off thumps. I've talked to people who had tweeters destroyed by that.

 

[abdo123]

Some amps have huge turn-on and turn-off thumps. I've talked to people who had tweeters destroyed by that.

a big turn-on and turn-off thump is a big red flag for a terribly designed amplifier.

 

[fpitas]

a big turn-on and turn-off thump is a big red flag for a terribly designed amplifier.

Well, sort of. A solution is an output relay that only closes when the output stabilizes. That's what a lot of amps do. It's a rare amp that doesn't have some thump. Generally no one cares a lot because woofers are kind of indifferent, within reason.

 

[Ken Tajalli]

Well, sort of. A solution is an output relay that only closes when the output stabilizes. That's what a lot of amps do. It's a rare amp that doesn't have some thump. Generally no one cares a lot because woofers are kind of indifferent, within reason.

OR
leave it on 24/7 - as we did.
And a big capacitor hardly helps anyway.

 

[fpitas]

OR
leave it on 24/7 - as we did.
And a big capacitor hardly helps anyway.

JBL thinks it does, in any event. They suggest a value that places the pole an octave below the crossover. Me, I just bought an amp that only has about 1mA thump

 

[Rick Sykora]

JBL thinks it does, in any event. They suggest a value that places the pole an octave below the crossover. Me, I just bought an amp that only has about 1mA thump

Diving a bit deeper, this protection cap typically needs to be 20 uF or more. Could easily be twice that depending on crossover frequency and filter order.

Those are BIG caps when you buy something nicer than an electrolytic.

 

[ROOSKIE]

Not wrong if the active speaker do not filter the unnecessary frequency for the drivers. All ASR review doesn't tear up the studio monitor to measure if the driver are receiving full range or filtered frequency.

Howdy are you trolling here? Seriously, an active speaker uses active filtering. That is why it is called an active speaker and an active filter is called 'an active filter' because it use power(needs to be plugged in). Passive filters are called such as they filter without needing additional power supplied. This is not complex. Sorry, I have to assume you are trolling, if not so be it. These GR based threads!

I think that is what Danny thinks, yes.
To which i said, even in an active speaker, one would certainly protect a tweeter from all that low frequency nonsense with a capacitor.

View attachment 261958
Engineer, thinking about LF artifacts, 1974, colorized.

If there is no such capacitor it means the engineer was confident that either there aren't any LF artifacts in the first place, or they don't matter.

Diving a bit deeper, this protection cap typically needs to be 20 uF or more. Could easily be twice that depending on crossover frequency and filter order.

Those are BIG caps when you buy something nicer than an electrolytic.

A munfacturer might use a capacitor but some may not. In my DIY I have never used one and have never had a problem.
The reason as suggested by several to avoid using one is the cost of using a large high quality cap which may cost more for DIY than a decent tweeter. Obviously losing a $400 Be tweet would suck but I have never had any sort of even slight issue. I just work carefully and make sure I never fire the speaker up without the proper programming activated and I don't use amps with lots of on/off pop.

 

[fpitas]

Diving a bit deeper, this protection cap typically needs to be 20 uF or more. Could easily be twice that depending on crossover frequency and filter order.

Those are BIG caps when you buy something nicer than an electrolytic.

When pushed to it, I've used polypropylene motor run caps.

 

[TheBatsEar]

a big Woofer can defintely produce high frequencies at high volumes.

Yes, but we are talking background hiss levels of an amp in an active speaker, not high volumes of high frequency content.
It's just not the problem Danny tells us it is. He invents it to sell his wares, that is all.

 

[fpitas]

Someday if Danny starts selling active speakers, all these "problems" will mysteriously vanish