Top end monitors "box sound" vs OB

[jmf11]

Hello,

I recently viewed a Burning Amp video from S. Linkwitz, where he is "against" vented boxes because of box resonnance, port noise and so on (

). I wonder if this also affects top end monitors like Genelec, Neumann...

Can proper engineering and manufacturing allowtures to avoid 100% of the "box" adverse inconveniences compared to an Open Baffle, on related criteria?

I'm curious of those studio monitors that pack incredible performance, but would not like to be disapointed. I'm also curious of science and wonder if Spinorama captures the "vented box issues" or not. On one side I see great vented box products that objectively and subjectively perform extremely well. On the other side, I see knowledgeable persons like S. Linkwitz 100% against that same concept.

I currently have LX-Minis (and a pair of Tannoy Berkeley). My audiophile journey went through Open Baffle (with Supravox complemented with JBL compressions). I know the difference between monopole, dipole, cardioïd. So sure the bow will not in the room the same way as an OB or Cardioid.

Best regards,

JM. Fourneron

 

[tuga]

Here are some of Linkwitz' comments on box speakers which I posted in another topic:

• Box loudspeakers
• Typical box speakers have a generic sound due to their polar response, panel resonances, re-radiation through the cone and vented bass.
• Bass from box speakers has more "punch" than from open baffle speakers, but is less "airy".
• Vented bass speakers are resonant structures and store energy which is released over time. For accuracy, bass must be reproduced from sealed or open baffle speakers that are non-resonant.
• Closed box speakers are best listened to from very close distance to minimize masking from an uneven room response.

Siegfried Linkwitz' thoughts on loudspeakers and domestic reproduction

Linkwitz' thoughts on loudspeakers and domestic reproduction http://www.linkwitzlab.com/conclusions.htm A few clippings with which I concur: • Loudspeakers • The best one can hope for with 2-channel sound reproduction is the illusion of listening into the recording venue...

www.audiosciencereview.com

 

[jmf11]

Thanks tuga for that complement to my question. Which reinforces my interrogation, wether this can still be heard in top end monitors, or if those flaws have been addressed and are below the audibility threshold in good designs.

JMF

 

[thewas]

These two posts from KEF engineers give also some good insights in the topic:

KEF R Series with MAT white paper

Ref 1 Meta:

www.audiosciencereview.com

KEF R Series with MAT white paper

Ref 1 Meta:

www.audiosciencereview.com

 

[tuga]

These two posts from KEF engineers give also some good insights in the topic:

KEF R Series with MAT white paper

Ref 1 Meta:

www.audiosciencereview.com

KEF R Series with MAT white paper

Ref 1 Meta:

www.audiosciencereview.com

If one compares the response of sealed vs ported in the time domain the latter shows 'ringing' or longer decay (not different from room-induced resonances).
The amplitude and duration of that 'ringing' will depend on how the port system is tuned/designed.

 

[thewas]

If one compares the response of sealed vs ported in the time domain the latter shows 'ringing' or longer decay (not different from room-induced resonances):

A well engineered ported design doesn't necessarily need to have them as accentuated, for example from the same measurement set:

Source of above: https://dt7v1i9vyp3mf.cloudfront.net/assetlibrary/n/ns10m.pdf

Also like the KEF engineers wrote in my quotes above in the bass the loudspeakers are mainly minimum phase so the transient response is inextricably linked to the frequency response. If you EQ the closed box to have the same response as the ported (using minimum phase EQ) then they would have the same transient response as one another. And as I had added in that thread the nice thing is that this also works the other way around, meaning you can EQ the ported version to the same response as the closed one getting also the very similar transient response but with the advantage of lower distortions. It should be also added that in typical rooms the bass decay behaviour is strongly dominated by the room modes which anyway need special care in form of acoustic or minimum phase counteractions.

 

[JohnnyNG]

Closed box speakers are best listened to from very close distance to minimize masking from an uneven room response.

Do sealed subs in the nearfield count?

 

[tuga]

A well engineered ported design doesn't necessarily need to have them as accentuated, for example from the same measurement set:

View attachment 280799
Source of above: https://dt7v1i9vyp3mf.cloudfront.net/assetlibrary/n/ns10m.pdf

Also like the KEF engineers wrote in my quotes above in the bass the loudspeakers are mainly minimum phase so the transient response is inextricably linked to the frequency response. If you EQ the closed box to have the same response as the ported (using minimum phase EQ) then they would have the same transient response as one another. And as I had added in that thread the nice thing is that this also works the other way around, meaning you can EQ the ported version to the same response as the closed one getting also the very similar transient response but with the advantage of lower distortions. It should be also added that in typical rooms the bass decay behaviour is strongly dominated by the room modes which anyway need special care in form of acoustic or minimum phase counteractions.

I agree. A well designed reflex system performs better than a badly designed one but it's still not a speaker driver.
But my anecdotal experience has generally been that systems tuned to 30Hz or below have no audible issues.

It would be interesting to see e.g. a Reference 1 measured in the same way as was done by Newell above.

 

[tuga]

Do sealed subs in the nearfield count?

Unfortunately Linkwitz is no longer with us to answer your question. My anecdotal experience has been that when operating below 30Hz ports have not presented audible issues, but I don't listen to electronica so most of the programme I have probably rolls off at around that frequeny anyway.

 

[anmpr1]

I recently viewed a Burning Amp video from S. Linkwitz...

SL had ideas, for sure. How did his research and creations relate to the average consumer attempting to buy something he might like? Given his criteria, it's not a quick and simple thing to parse. How to compare, and is a direct comparison among competing designs even possible, for the consumer?

He argued that the problem with loudspeaker A/B comparisons is that they are typically done sans a reference. The reference should be a live (acoustic) instrument. But then the question is, which instrument? How many acoustic instruments? The type of music the instrument(s) is/are playing, the venue and listener position, and so forth. With not even a large number of instruments, it's pretty unworkable. Forget about A/B ing an orchestra with a loudspeaker. And what if you prefer Maxell Blown Away music? What are you supposed to do, then?

At least with a simple 'live' instrument v loudspeaker, one can make a local comparison. It's not exactly like hamburgers, where 75 out of 100 blindfolded people prefer a Big Mac to the Five Guys. Does that mean a Big Mac is the best burger, because most people like it? What can you use as the reference burger? However, the relation between burgers and a loudspeaker is not that far fetched, because of the abovementioned problem with selecting the appropriate 'live instrument' reference. And, to expand on SL, if you don't have the 'live' reference, you might as well be comparing burgers, as it comes down to which sounds (tastes) better to the 'panel', and how many people like this, as opposed to that.

Next, and most depressing, sans a true live comparison, all leads back to the recording, which is generally a mess, however you look (hear) at it.

Keeping with a food metaphor, in our modern times, a loudspeaker consumer is out to lunch. Where can he go in order to side by side audition? Unless one lives in a very large city, there are likely no audio dens available for direct, extended product comparison. And even if there are, choice is limited. Then he gets it in his living room, and it sounds different. Maybe he likes it more with time, maybe he doesn't. Is the 30 day free trial enough time?

Many by necessity buy mail-order, with the promise of a shipping label for return if they don't like it. This is workable for the smaller shoebox (the kind SL didn't like), but with larger form factor loudspeakers it becomes rather a hassle. And however it is, you won't find that mail-order deal with SL's LX--at least as far as I know.

SL admitted that what he was going for was ultimately a preference, delimited by vagaries of the recording, not to mention (and how can you not mention it?) the 'stereo' format, which he called (and rightly so) an illusion. Plus, as good as his system was/is (and it's a fine loudspeaker), it's not something you can order from Crutchfield, and then expect it to be delivered, the next day. His route to good sound is not a trivial pursuit, given the system's overall components.

In any case, IMO the idea of having 'real live sound' in your living room, using a recording, is, idiotic. Or, if I want to be kinder, it is just a confused goal. If that's what you want, learn to play an instrument, because you won't get it with your hi-fi. The best advice I've found is to buy something you think you will like, that you can afford, that fits your idea of living room aesthetics and integration, and then enjoy it for the music. Listen to the music as an illusion, and not your system.

 

[fpitas]

FWIW, I adjust the box size and port tuning for minimum group delay when I make a ported enclosure. I still like sealed better, but that helps a lot when ported is necessary.

Small woofers in a ported box are kind of an unfair comparison to OB.

 

[DVDdoug]

There are trade-offs and compromises with ANY speaker design. You can make a good sealed or ported speaker. But if you thrown a random speaker in a random box, a sealed design is usually going to work better.

(My DIY subwoofers are ported.)

The driver characteristics* also determine whether a sealed or ported box works better.

There are some generalizations - A ported box can generally have a lower -3dB point than a sealed box and you can tune it to go lower if you allow a small bump somewhere above the cutoff. For example a little +1 or +2dB bump that allows the bass to go lower is usually "worth it" (IMO). Below the -3dB point, most ported speakers drop-off at -12dB per octave.

A sealed box usually has a higher -3dB frequency. But below the -3dB point it usually drops at -6dB per octave.

This means that at very-low frequencies where both designs have weak-output, the sealed box can "win". With big woofers in big boxes (or multiple big woofers & boxes), a lot of amplifier power, and EQ, the sealed design may put-out more very-deep and subsonic bass.

...compared to an Open Baffle,

There are good reasons that open baffle speakers are not common.



* Thiele and Small did some experiments in the 1970s so drivers could be measured and performance in different boxes could be predicted. Later when computers became commonly available it was MUCH easier to design a good speaker with less trial-and error. Ported boxes today are generally better than they were 50 years ago.

For most woofers you can look-up the Thiele-Small parameters and plug them into a program like WinISD to compare and optimize a sealed or ported box.

 

[jmf11]

So, it looks like there are good reasons that most designs are ported box ones... as long as it is done well. I tried to read the KH150 waterfall graph to compare to the above (https://www.audiosciencereview.com/...mann-kh-150-monitor-review.39922/post-1406634), but the scale does not allows to see when the lower frequencies resonnance stop for that Speaker.

Other designs like OK have also their reason, but seems it would be more related to the searched for radiation pattern.

I downloaded the the Kef whitepaper. Have to dig in, but several sections deal with the design of the port, showing that this has to be taken care of.

Thanks for the shared elements.

JMF

 

[badspeakerdesigner]

Curious timing on this, I've been looking to delve into a little open baffle build just to see what the hubbub is all about. I'm a little skeptical of the results but it's something I just have to hear. One of the things that comes up a lot when researching OB is folks talking about getting away from the "box" sound. I had to ask myself though, what even is the box sound? Can I hear the box sound or the cabinets of my current speakers? I don't really think I can hear much of a sound of the box or a sound that I'd argue is translatable between other box speakers. All my speakers sound quite a bit different.

I've watched the video posted above and I agree with some of things SL said, like how moving left or right with traditional speakers causes one side to just kinda disappear. Some I did not, and some I did but questioned whether or not it's applicable to speakers, such as reflections being necessary for us to assess our surroundings but I question whether speakers would benefit from those reflections. I have dabbled with a tiny BMR driver in free air and it has some nice aspects (very enveloping sound), and some not so nice (diffuse as all hell, zero imaging).

I'm hoping that I end up with something I at least like enough to keep around.

 

[tuga]

So, it looks like there are good reasons that most designs are ported box ones... as long as it is done well.

What are those reasons?
Remember that the port is operating in the sub-bass region, also that ideally those speakers will be partnered with subs and high-passed above the port tuning frequency.
The port is no more than a crutch...

The first Bowers & Wilkins 801(F/Series 80) was a sealed cabinet design.
The following model, the 801 Matrix, switched to reflex allegedly at request of studios which wanted higher-SPL capabilities and increased low end extension. Probably better driveability too.
A pair of the sealed speakers with subs would have performed better in the test bench...

 

[tuga]

The following was taken from Neumann's "Glossary - Measurements Description":

 

[fpitas]

The following was taken from Neumann's "Glossary - Measurements Description":

That illustrates that a 4-way beats a 3-way (believable), but I wonder how big the woofer in the 3-way was.

 

[fpitas]

Talking about IMD, I can only imagine the IMD you get with open baffle woofers.

 

[thewas]

I agree. A well designed reflex system performs better than a badly designed one but it's still not a speaker driver.

Of course not and nobody claimed such, the typical comparison is ported vs closed baffle design.

 

[fpitas]

I still think the comparison is flawed, vented small monitors vs open baffle bass. Open baffle bass speakers are enormous by necessity, with relatively tremendous cone movement.