Why do passive speakers still exist?

[steve59]

I just got banned from another forum for saying that digital is better than vinyl

Saying digital is different than saying "I prefer digital to vinyl". The other hifi sites allow for a bit of individual preference and wouldn't ban you for stating a personal preference, right?

 

[Pearljam5000]

Saying digital is different than saying "I prefer digital to vinyl". The other hifi sites allow for a bit of individual preference and wouldn't ban you for stating a personal preference, right?

You can't say that digital is technically superior to vinyl and more accurate.
That's what got me banned .

 

[Bjorn]

So if the right question is "Would an active Salon2 be better than a passive one?", is that not analogous to the question of "Would an active Summa be better than a passive one"?

If so, then arguably the benefits may not be not very significant. I'm not saying they're non-existent, and agree that DSP enables design choices which would otherwise be impractical. But I'm not convinced that DSP is necessary in order to produce a very high quality loudspeaker, and nor that whether a speaker uses DSP is a primary determinant of sound quality.

(For the record, I'm developing a speaker that uses DSP, because it enables a couple of design choices which would otherwise be impractical.)



Earl did not use the Pioneer receiver to amplify the active version.

My understanding is that that cheap Pioneer receiver had very low crossover distortion and therefore scored quite high by the GedLee Metric, which is a far better predictor of subjective preference than traditional harmonic and intermodulation distortion figures. Here's another clip, cued up to the most relevant section which starts at 4:20, and goes to about 17:50:

If the Summa/Abbey were close to being physcially time aligned (I assume they were close to but not perfect), the difference between active and passive would be less vs a Salon2 or most other speakers. Time alignment is perhaps the biggest advantage with active. While it's possible to do that physically for all speakers with for example slanting the cabinet or placing drivers behind others, this comes with negative consequences. An exception would exactly be a short waveguide, where the driver is naturally placed behind the other and without the drawback of diffraction.

Other than that it become pure speculation how much Geddes' speakers would gain from being active without doing a test. I wouldn't put much trust in Geddes own testing or words here.

Yes, crossover distortion can be really hideous and very audible. But I still believe noise and other types of distortion needs to be at lower level than electronics like a low cost Pioneer surround receiver and the older miniDSP HD crossovers to be audible transparent.

 

[gnarly]

So if the right question is "Would an active Salon2 be better than a passive one?", is that not analogous to the question of "Would an active Summa be better than a passive one"?

I do think that is the right question....in fact I'd say it's the only valid comparison.

With regard to the Summa....i think it is an example of a simple two-way, where any potential differences between active and passive get diminished.
(I've tried to stress this point of number of times .)
It uses a single compression driver & waveguide, crossed over to a single well chosen 15" woofer. A relatively low order xover probably works fine.
Perhaps delay between drivers could improved a little via active, and bi amping might bring some extra life to it...but I wouldn't expect any major sonic gains to unless pushing the box to high SPL. (an underpowered amp is probably an issue with passive here, imo.)

With regard to Geddes take on THD, and it's lack of audibility due to masking....
I'd like to believe it, but one of his main points is that as SPL rises, masking increases.
Maybe it does,...... but i continually wonder why do (all) speakers get more strident sounding as their volume is turned up.?

Well, i know there's thermal compression and amplifier clipping on peaks.
But I don't see how those factors alone can be the whole story, when it comes to turning strident with SPL.

I know my DIYs with their multi-way amplification channels don't come close to thermal compression or amp clipping.
And are have very low THD and IMD at 115-120dBZ @ 1m throughout the spectrum. But somewhere above there, stridence begins to set in.
And the stridence can't be attributed to room resonances/reflections, or ears being overpowered, because this is heard outdoors where I just back up to maintain an equal comfortable SPl level.

And as audible stridence rises....well, so does measured THD.
So I dunno what to think about Geddes claim.

 

[Duke]

If the Summa/Abbey were close to being physcially time aligned (I assume they were close to but not perfect), the difference between active and passive would be less vs a Salon2 or most other speakers.

Good call. I was present for the design phase of an early iteration of the Summa's passive crossover, and the depth of the waveguide does indeed enable time alignment with a passive crossover. I take advantage of that same characteristic in all of my speakers, but don't emphasize it in my marketing because imo it's of less audible significance than the overall acoustic design.

Time alignment is perhaps the biggest advantage with active.

Very interesting to hear you say that. If time alignment is indeed the biggest advantage of going active (assuming generally competent design), I now understand why you see greater room for improvement in an active Salon 2 than in an active Summa.

While it's possible to do that physically for all speakers with for example slanting the cabinet or placing drivers behind others, this comes with negative consequences. An exception would exactly be a short waveguide, where the driver is naturally placed behind the other and without the drawback of diffraction.

Imo Earl's approach to loudspeaker design is a remarkably elegant one, primarily from the standpoint of radiation pattern uniformity but also in lack of compression, freedom from diffraction, and inherent ime alignment. My "target curve" is a bit different from Earl's, and an active system would facilitate adjustments to the frequency response curve.

 

[Duke]

With regard to Geddes take on THD, and it's lack of audibility due to masking....
I'd like to believe it, but one of his main points is that as SPL rises, masking increases.
Maybe it does,...... but i continually wonder why do (all) speakers get more strident sounding as their volume is turned up.?

I'm not an expert on the audibility of distortion.

My understanding is that there are types of distortion which ARE NOT SUBJECT TO MASKING, and these are often the ones which cause speakers to get more strident as the volume is turned up.

The ear/brain system's masking characteristic is effective when the distortion occurs at the same time as the signal (as is typically the case with harmonic distortion), but masking is not effective when the distortion arrives later in time. A classic example is a diffraction horn. The diffraction slot is in effect a secondary sound source which has a slightly longer path length, and therefore is not masked by the louder non-diffracted component of the sound. The ear/brain system has a NON-LINEAR perception of this type of distortion; that is, it becomes progressively more audible and objectionable as the SPL rises. People often attribute harshness at high SPLs from a PA system to "distortion in the compression driver", but that is very seldom the case; thermal or mechanical damage would occur if the compression driver were driven into audible distortion for hours at a time. The distortion component (the relative amount of sound that is diffractive) is not changed with level therefore it is a "linear distortion"; rather it is the ear's PERCEPTION of this type of distortion that is non-linear.

The in-room reflections themselves (especially off of surfaces near the speakers) could easily be a source of increasing stridency as SPL goes up, as they arrive way too late to be masked.

 

[Rmar]

An un-weighted list of one guys Hi-Fi quirks...(mine)

1. Risk of house wiring noise getting into the speaker
2. Less freedom to choose amp and other electronics in the signal path
3. Another point of failure in the system (another part to repair or replace someday)
4. Less freedom of speaker placement (not dependent on AC outlet locations)
5. One more cable in my system (actually two more - one per speaker in a system that has too many cables already))
6. One more step in my system's "turn-on/turn-off" protocol

 

[gnarly]

The ear/brain system's masking characteristic is effective when the distortion occurs at the same time as the signal (as is typically the case with harmonic distortion), but masking is not effective when the distortion arrives later in time. A classic example is a diffraction horn. The diffraction slot is in effect a secondary sound source which has a slightly longer path length, and therefore is not masked by the louder non-diffracted component of the sound. The ear/brain system has a NON-LINEAR perception of this type of distortion; that is, it becomes progressively more audible and objectionable as the SPL

Interesting. Doesn't that make a case for the value of time correction?

Dave Gunness at Fulcrum Acoustics advocates impulse-response correction of internal horn reflections.
https://www.fulcrum-acoustic.com/audio-technology-insights-resources/temporal-equalization-tq/
He along with TDanley, have been two of the men I try to keenly study. I work to add Dave G's processing techniques into T Danley's acoustic design methods.

Oh, btw....in one of the Geddes vids you linked, he discussed DSL's use of passives. DSL's main market is install...particularly large outdoor arena/stadiums.
Often requires speaker placements in difficult to service, weather exposed locations. And can be expensive to get code approved AC power to.
Passives often fit their biz model quite well, i think.
It's worth noting DSL's larger studio models have gone active.

 

[Duke]

Interesting. Doesn't that make a case for the value of time correction?

Dave Gunness at Fulcrum Acoustics advocates impulse-response correction of internal horn reflections.
https://www.fulcrum-acoustic.com/audio-technology-insights-resources/temporal-equalization-tq/

I can see how a very worthwhile improvement can be made using Dave Gunness' approach.

My preference is to use a non-reflective horn to begin with, which Gunness mentions as a possible solution but it requires more real estate than may be available in a prosound application.

...in one of the Geddes vids you linked, he discussed DSL's use of passives. DSL's main market is install...particularly large outdoor arena/stadiums.
Often requires speaker placements in difficult to service, weather exposed locations. And can be expensive to get code approved AC power to.
Passives often fit their biz model quite well, i think.
It's worth noting DSL's larger studio models have gone active.

I'm drawing a blank - who is "DSL?"

I work to add Dave G's processing techniques into T Danley's acoustic design methods.

Gnarly! (Sorry, couldn't resist!) I try to incorporate some of David Griesinger's thinking into my loudspeaker system designs, and in doing so I depart from Earl Geddes' approach.

 

[gnarly]

I'm drawing a blank - who is "DSL?"

Sorry Duke, Danley Sound Labs

 

[dannut]

Dave Gunness at Fulcrum Acoustics advocates impulse-response correction of internal horn reflections.
https://www.fulcrum-acoustic.com/audio-technology-insights-resources/temporal-equalization-tq/

It only works for the single mouth reflection, that is equally delayed wrt. radiation angle. Most horns are.. not properly designed. So they have complex reflections and a resulting complex interference pattern. Easy to spot on a detailed polar map (well who publishes that?!) - resonance-like phenomena that shifts around in frequency with observartion angle. By definition can't be equalized (1D DSP solution doesn't work for a 3D radiation problem)

About harshness... as Duke pointed previously, sadly there is so little research on the audibility of 'stridency'. All that has been done (all 2 of them ) point to the phenomena where suddenly a delayed-reflection type signal gets unmasked above a certain listening level. More thourough research not going to happen due to levels permitted on subjects.

Conversely - there are comprehensive studies on nonlinear distortion. Most recent ones (Voishvillo, Geddes) point to the same conclusion - distortion components in properly engineered electroacoustic transducers are of low-order, therefore harmless. They increase with drive level, but so does auditory masking. Until a limit is reached and they get annoyingly audible even on regular program material.

So concur with Duke's recommendation - clean wavefront is paramount to good sound. And design systems to be utilized in their linear operating range.

 

[NIN]

Let's rememeber that also with Geddes' speaker it was an objective improvement according to him. But how much that was subjectively, is impossible to know without testing it properly. Geddes used electronics in his system with quite high distortion (cheap Pioneer receiver), and his active crossover was an older miniDSP that wasn't transparent either. So he had bottlenecks. In his optinion that didn't matter and wasn't audible, something I disagree with.

I have nothing against active speakers. It is just the the cult-like behavior of people who can't understand why every loudspeaker isn't active.

 

[kma100]

I think people get swept up with absolutes. Perhaps in *theory* an active speaker is "better" (whatever that means) than a passive speaker, but there are some very well regarded passives...

 

[Anton D]

I have nothing against active speakers. It is just the the cult-like behavior of people who can't understand why every loudspeaker isn't active.

Audiophilia is rife with the hegemony of those who are frequently wrong but never in doubt.

 

[NIN]

Loads of reasons why passive designs still exist none of which pertain to sound quality.
Keith

Not true.

 

[gnarly]

It only works for the single mouth reflection, that is equally delayed wrt. radiation angle. Most horns are.. not properly designed. So they have complex reflections and a resulting complex interference pattern. Easy to spot on a detailed polar map (well who publishes that?!) - resonance-like phenomena that shifts around in frequency with observartion angle. By definition can't be equalized (1D DSP solution doesn't work for a 3D radiation problem)

Good point. I think 1D corrections that are assumed to work for 3D issues, are at the root of many errors.
From simple speaker design addressing acoustic offsets, refraction, and horn anomalies on the radiation end.....and room correction on the receiving end.

My simple minded way of accepting I don't understand what 1D can and cannot do for 3D issues, and still move forward, is to measure across acoustic space.
If 1D corrections hold well across polars, then I assume they are valid amd keep them. If not, they get tossed.

About harshness... as Duke pointed previously, sadly there is so little research on the audibility of 'stridency'. All that has been done (all 2 of them ) point to the phenomena where suddenly a delayed-reflection type signal gets unmasked above a certain listening level. More thourough research not going to happen due to levels permitted on subjects.

Conversely - there are comprehensive studies on nonlinear distortion. Most recent ones (Voishvillo, Geddes) point to the same conclusion - distortion components in properly engineered electroacoustic transducers are of low-order, therefore harmless. They increase with drive level, but so does auditory masking. Until a limit is reached and they get annoyingly audible even on regular program material.

Yeah sigh....I just can't accept that limited amount of research yet.

Hey, here's one avenue I've been exploring about stridency and clarity in general, that I find a bit amazing.
The more "ways" I've added to unity/synergy horns, the greater the clarity they have achieved. This is despite the added crossovers and complexity. (albeit I do use linear phase xovers). Don't even need to use all the ways, and can compare with or without some of them...that much overlap is available.
And not only just clarity, SPL capability before stridency increases with added ways too.

I'm really left thinking some form of modulation distortion is being reduced by decreasing the octave span each driver section has to cover.. But dunno.

So concur with Duke's recommendation - clean wavefront is paramount to good sound. And design systems to be utilized in their linear operating range.

Yep, I know Geddes believes a diffraction-less waveguide rules. I do too, other than so far they have only proven to hold up thru the top-half of the audio spectrum, if that.
I'm finding working with the bottom half of the spectrum to be more rewarding sonically.......cause really, the top half is pretty easy.

And YES, clean linear SPL including headroom, throughout the spectrum ? AMEN !

 

[JiiPee]

I have nothing against active speakers. It is just the the cult-like behavior of people who can't understand why every loudspeaker isn't active.

I have nothing against passive speakers. It is just the cult-like behavior of people who are spreading unfounded FUD against active speakers.

 

[Purité Audio]

If contemporary active loudspeakers ( constant directivity, full-range , adjustable bass output , inbuilt peq etc etc) had been developed first and then someone suggested ‘let’s make a speaker with limited extension no adjustment which is sensitive to the power amplifier, arbitrary positioning, ‘ the thought would be ridiculous.
Keith

 

[dannut]

My vote goes to hybrids. Passive xo between ways, phase linearization, eq/bafflestep in dsp. Not for performance reasons, but simplicity.

With actives, that houses the electronics in the speaker - the joy of retrofitting signal AND power for a multichannel install.
With actives, central amplification - the joy of 22-33ch of external amplification...

If only we had speakers that could be run off of an AVR... simple life.

 

[JiiPee]

My vote goes to hybrids. Passive xo between ways, phase linearization, eq/bafflestep in dsp. Not for performance reasons, but simplicity.

With actives, that houses the electronics in the speaker - the joy of retrofitting signal AND power for a multichannel install.
With actives, central amplification - the joy of 22-33ch of external amplification...

If only we had speakers that could be run off of an AVR... simple life.

Maybe I misunderstood something, but if You already have DSP for eq etc.., how does it make things simpler when You the add passive xo network, instead of using the DSP-capability that is already there ?