Active Speakers - will this time be different?

steve59 said:
I think active is a good way to minimize cabinet size regarding bass, and eliminates the worry of component matching, but I listened to the atc active vs passive demo at axpona, last one b4 covid and tbh I didn't notice a difference in the 5 minutes it took to swap speakers
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Passives typically have a mid bass bump due to the crossover elements.



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Nikhil said:
Passives typically have a mid bass bump due to the crossover elements.
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That isn't inherent to passive speakers/components. In fact, the opposite, since "midbass" falls in the frequencies where the front baffle becomes small relative to wavelengths being emitted, resulting in an on axis loss aka "step" in output as the waves simply wrap around the baffle.
If a loudspeaker has a midbass hump, its by design. Inadvertent or not. I think a lot of audiophiles misread Stereophile plots...

cheers,

AJ
 
nearly every ported speaker design has a 10 db rise around 100 hx and if I'm reading you correctly you're saying because the wavelength is larger than the baffle it, what ? evaporates?? please expand.

The thing about those measurements is they are pretty consistent.
 
10db??
Where are you seeing this Steve, link?
Random sample, latest passive bookshelf review at SPhile:
422Fleetfig3.jpg

That's a 5db "hump" completely due to the nearfield measurement (mic <1 inch from woofer cone), as it states in the review just below graph:
The black trace below 300Hz in fig.4 shows the complex sum of the nearfield woofer and port responses. The boost in the loudspeaker's upper bass will be due to the nearfield measurement technique, which assumes the drive-unit is mounted in a true infinite baffle, ie, one that extends to infinity in both planes.
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IOW, measured at say 1m or more away, the "hump" is gone, the response will flatten, because the speaker baffle is finite, the waves wrap around it. This is in front. Measure to side or behind, its still there for most part.
Again, most audiophiles simply don't understand how to translate the measurements. That's there by design, its often called "baffle step compensation" (Google it). It has zero to do with any inherent feature of passive crossover components. Its by design, yes of course, using said passive components. A typical active (home audio) bookshelf will have it also, via EQ. Studio monitors may/may not, due to different placement requirements, atop mixing consoles, etc., rather than free standing.

cheers,

AJ
 
how about the jbl 4357? I ,look at floorstanding designs that attempt deep bass, your examples have nothing to do with my initial question
 
steve59 said:
how about the jbl 4357? I ,look at floorstanding designs that attempt deep bass, your examples have nothing to do with my initial question
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Presume typo and you mean JBL 4367. Perfect, thanks. Stereophile measurement using nearfield woofer technique
422JBLfig3.jpg

Per JA:
The nearfield response of the woofer (fig.3, blue trace below 350Hz) has the expected notch at the ports' tuning frequency, which is when the back pressure from the port resonance holds the diaphragm stationary. The 5dB peak in the upper bass is due entirely to the nearfield measurement technique, which assumes the drive-unit is mounted in a true infinite baffle, ie, one that extends to infinity in both planes.
Click to expand...
Same JBL measured with a Klippel, NOT using nearfield woofer technique:
CEA2034%20--%20JBL%204367.png

The "hump" has evaporated ;).
It is an "artifact" of the measurement method. JA doesn't/can't measure LF anechoically to get an accurate measurement, so he uses the correct alternate technique....which obviously leads to confusion unless one has read his measurements method article, buried somewhere on Stereophile. He does, as I quoted above, note it with each review.
Once again, no 'hump' is inherent to passive speakers. Just individual design. Not defending them, as this type of 19th century tech is one of many reasons why I came off the sideline and started rolling my own. Just wanted to set the record straight.

cheers,

AJ
 
AJ Soundfield said:
That isn't inherent to passive speakers/components. In fact, the opposite, since "midbass" falls in the frequencies where the front baffle becomes small relative to wavelengths being emitted, resulting in an on axis loss aka "step" in output as the waves simply wrap around the baffle.
If a loudspeaker has a midbass hump, its by design. Inadvertent or not. I think a lot of audiophiles misread Stereophile plots...

cheers,

AJ
Click to expand...


Point taken but what I really meant is perhaps related to the phase issues at the crossover points. I don't claim to be an expert on these things but I thought this (the mid bass "hump") was how passive speakers were affected at the crossover frequencies - the actual effect depending of course on the crossover network design. I've since been informed that this can also be heard as a smearing of detail or even a thinning of the sound.

p.s. Please leave out the graphs and snark on here. This isn't ASR.
If you say something nicely enough we will believe you. Honestly. :cool::cool:



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I'm not sure if I heard the same year demo as you, it didn't take long to switch systems, I think they just shared the source, I thought the active system sounded better. In fact, that active system impressed me, a lot. Outstanding reproduction of drums IMO

steve59 said:
I think active is a good way to minimize cabinet size regarding bass, and eliminates the worry of component matching, but I listened to the atc active vs passive demo at axpona, last one b4 covid and tbh I didn't notice a difference in the 5 minutes it took to swap speakers
Click to expand...
 
I have no doubt that had they been faster at swapping the speakers out I would have more readily noticed a difference.
 
AJ Soundfield said:
Presume typo and you mean JBL 4367. Perfect, thanks. Stereophile measurement using nearfield woofer technique
422JBLfig3.jpg

Per JA:
Same JBL measured with a Klippel, NOT using nearfield woofer technique:
CEA2034%20--%20JBL%204367.png

The "hump" has evaporated ;).
It is an "artifact" of the measurement method. JA doesn't/can't measure LF anechoically to get an accurate measurement, so he uses the correct alternate technique....which obviously leads to confusion unless one has read his measurements method article, buried somewhere on Stereophile. He does, as I quoted above, note it with each review.
Once again, no 'hump' is inherent to passive speakers. Just individual design. Not defending them, as this type of 19th century tech is one of many reasons why I came off the sideline and started rolling my own. Just wanted to set the record straight.

cheers,

AJ
Click to expand...

this is a clear difference on paper and I am seriously out on a ledge talking about measurements, which measurement would more likely predict in room response?
 
steve59 said:
this is a clear difference on paper and I am seriously out on a ledge talking about measurements, which measurement would more likely predict in room response?
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Unfortunately neither, except above the transition frequency of a couple hundred Hz where "speaker" dominates. Below, its entirely predicated on the rooms dimensions, construction/rigidity/lossiness of surfaces, placement, seat, etc.,along with the speaker design itself.
In the case of the wide JBL with 15" woofer, there is significant forward beaming of the response, which means it holds up ok about 200 hz (where even a 15 stops beaming):
422JBLfig7.jpg
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Something like your narrower Blade (yes, I know side mount woofers) will go omni a bit higher, so you will see room effects correspondingly higher in frequency.
The good news with both is that you know they are somewhat even (monopoles) LF output prior to any room effects.

cheers,

AJ
 
Nikhil said:
Point taken but what I really meant is perhaps related to the phase issues at the crossover points. I don't claim to be an expert on these things but I thought this (the mid bass "hump") was how passive speakers were affected at the crossover frequencies - the actual effect depending of course on the crossover network design. I've since been informed that this can also be heard as a smearing of detail or even a thinning of the sound.
Click to expand...
You're probably talking about the different types of crossover filters, affecting one or both of amplitude or phase. It's succinctly described and illustrated under the Common types section of the Linkwitz-Riley filter Wikipedia entry. I would not expect a speaker designer to pick a "wrong" crossover filter.

There is typically a time-offset between the different drivers of a speaker's different crossover sections, seen for example in Stereophile step response speaker measurements, which I would expect you could eliminate or compensate for using only active crossovers and the appropriate DSP. But I can't recall ever seeing a published measurement to confirm that.
 
NekoAudio said:
You're probably talking about the different types of crossover filters, affecting one or both of amplitude or phase. It's succinctly described and illustrated under the Common types section of the Linkwitz-Riley filter Wikipedia entry. I would not expect a speaker designer to pick a "wrong" crossover filter.
Click to expand...


Yes the crossover network used affects amplitude and phase at the crossover points. It's not that the designer uses a wrong crossover intentionally of course but is forced to make a design choice as the behavior of the crossover elements vary as frequency and temperature of the elements fluctuate. In actives the drivers just don't see the crossover.


NekoAudio said:
There is typically a time-offset between the different drivers of a speaker's different crossover sections, seen for example in Stereophile step response speaker measurements, which I would expect you could eliminate or compensate for using only active crossovers and the appropriate DSP. But I can't recall ever seeing a published measurement to confirm that.
Click to expand...

There is a nuance here i.e. time coherence and phase coherence which gets used interchangeably. Time coherence is when the drivers are acoustically aligned. All crossovers, active or passive, affect phase. But yes you are right in that crossovers can be designed to be phase coherent.




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steve59 said:
Same speaker, the nearfield measurements and in room. as an end user the second is easier to understand and looks much better. This pic does support your comment that JA's measurement doesn't really show actual response. I would rather see more of the second set of numbers as a consumer.
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Stereophile is one of the few publications that show both "at speaker" and "in room" response. However the caveat will be "that" room.
The measurements at LF should inform "how low" can you go, but not much else, especially in room.
Circling back, some active, especially typical studio monitors etc may have built in adjustable bass eq. Imperfect, but a start and better than none.

cheers,

AJ
 
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