[Tyson]

I agree with you both about the Serenity 7's (which I subsequently bought and now own), and the TAD's.  Both are top flight speakers.  Usually the tradeoffs between the 2 designs are:

OB - more open and airy sounding, easier to integrate into a typical room due to radiation patterns and overall sound presentation.  More laid back sounding.  Bigger sound stage.  Clearer/cleaner bass.

Box speakers - More precise sound, laser-like imaging, more forward sound presentation, more punchy and percussive sound, harder to integrate into a typical room.  More propulsive and authoritative bass.

I think as a designer you really have to pick your poison and design around the strengths of each.  I think what made the Super 7's unique (for me) was they had bass punch that I'd never heard in an OB speaker before.  Without that, I think I'd have felt that they were just another good (but not amazing) OB speaker. 

[AJinFLA]

if we're talking about bass, the LW design suffers from the same problem as every other full range OB speaker - musical bass that lacks punch and impact.

You've heard every full range OB speaker?? Wow.

I only posted about the OB Servo subs because they are a better solution for people looking to build an OB speaker.

In a remarkable coincidence you happen to have chosen to own them too.
They are indeed very good and most certainly a viable option, especially for DIY (or even I, a manufacturer). "Better" just might be in the eye of the beholder.
Btw, in another remarkable coincidence, the guy (PDR) who posted under your post that I quoted, seems to no longer have a servo dipole sub based system in his avatar. I wonder how this can be reconciled?

cheers,

AJ

[Tyson]

You've heard every full range OB speaker?? Wow.
In a remarkable coincidence you happen to have chosen to own them too.
They are indeed very good and most certainly a viable option, especially for DIY (or even I, a manufacturer). "Better" just might be in the eye of the beholder.
Btw, in another remarkable coincidence, the guy (PDR) who posted under your post that I quoted, seems to no longer have a servo dipole sub based system in his avatar. I wonder how this can be reconciled?

cheers,

AJ

Obviously the "every OB design" has an implicit "that I've heard" attached.  Don't be a douche. 

I'll let PDR answer about his own situation.  For myself I'd say there's a couple reasons "I" could move away from OB Servo subs in the future.

1. I get a box speaker.  I do think that box bass sounds best with box speakers.  I feel that OB bass is best with OB mids/highs and box bass is best with box mids/highs. 

2. The best box bass is still more punchy and percussive than even OB Servo bass.  OB Servo bass is more punchy than any other OB (or IB) implementation I've heard, and it's more punch than most box speakers I've heard.  But not all.  The best box speakers/bass is definitely more impactful than the OB Servo setup.

My favorite setup is mine, using the Super 7's.  But my 2nd favorite setup is Pez's which uses the VMPS RM40's run fully active (box speakers) and my 3rd favorite is a variation of the Gedlee Abbey (box speaker). 

[FullRangeMan]

Back to the original quote:
 "It is difficult to screw up an open baffle speaker design to where it sounds worse than your typical box speaker." - Siegfried Linkwitz.

Proof that even smart people exaggerate for emphasis- or perhaps it's taken out of context.  If you read this to mean that some diy OB drivers thrown into a baffle will be better than a cheaply but professionally designed box speaker, I don't agree.

I have listen various top money famous loudspeakers big and small in rich people homes and all they sound sterile due xover presence and have a poor 2D soundstage due driver is working inside a box.
Even so I still had to tell the proud host> Wow these your speakers are wonderful

[AJinFLA]

Obviously the "every OB design" has an implicit "that I've heard" attached.  Don't be a douche.

No it wasn't obvious, but thanks for now clearly making it so even a "douche" can see. Well then I guess there might be plenty other OB systems with "punch and impact", including Linkwitz based ones. It's just that in your opinion, there are none you've heard.

My favorite setup is mine, using the Super 7's.  But my 2nd favorite setup is Pez's which uses the VMPS RM40's run fully active (box speakers) and my 3rd favorite is a variation of the Gedlee Abbey (box speaker).

Great. Everyone has their preferences it seems.

[Russell Dawkins]

I think the issue of bass quality and variability is a huge one—perhaps the biggest untamed region in the whole issue of the processing and reproduction of recorded sound. I also think a large part of that is due to the way bass response is measured, particularly not taking into account the settling time of the system in response to signals at various frequencies through the range.

In other words, two speakers that measured identically flat right through the range of, say, 200 Hz on down when fed by a slow sweep might sound very different through that same range when fed a music signal, due to the slower settling time of one compared to the other; the one with the slower settling time sounding louder, and perhaps more 'impactful'.

Naturally, one hears what the mixing and mastering engineer intended when the result is listened to on the same speakers in a similar acoustic environment. I think it may well be that OB bass, sealed box bass and ported box bass are fundamentally different in predictable ways. If that is the case, then I suppose you are more likely to hear what the mixing/mastering engineers intended by listening on speakers that are similar in this regard and, with few exceptions, that would be a ported box more often than not, with sealed boxes a close second. Very few recordings are mastered on dipoles (I can think only of Mapleshade who did, and maybe Kavi Alexander) and even they may have used sealed box subs for the bottom octave.
Here's an in depth look at the problem—"The elephant in the control room":
http://www.soundonsound.com/techniques/elephant-control-room

[Davey]

It seems the discussion focus has narrowed to low frequencies now?  SL's preference (and the OP's original comment) regarding open-baffles is not just for bass frequencies.

I've talked to SL numerous times about this.  He considers the open-baffle approach inherently robust and superior to boxes.  Even efforts that are butchered by designers with minimal skills can/will sound halfway decent.  The radiation pattern is inherently superior....there are no box issues like re-radiation, stored-energy....they're generally much cheaper to construct....etc....etc....etc.

It's somewhat analogous to power amplifier design.  Even folks with minimal skill and electronics knowledge can "design" a tube power amplifier and probably have it sound halfway decent and not go up in a cloud of smoke.  However, the same can not be said of solid-state amplifiers.  You really need to know what you're doing to achieve audible success and good reliability.

I've listened to some fine box speakers over the years too.  But they do have their trade-offs.

Dave.

[PDR]

Btw, in another remarkable coincidence, the guy (PDR) who posted under your post that I quoted, seems to no longer have a servo dipole sub based system in his avatar. I wonder how this can be reconciled?

Well, thats easy enough, the Avatar is a pic taken from the front, the Servos are placed behind, left and right of the listening position.
The PAP Trio (Avatar) use 15" drivers that cross high 450Hz, the servos are for 100Hz and down. I guess you could consider the 15"
woofers and the servos sub woofers......now you can stop wondering, no remarkable coincidences to reconcile.

I've posted this on a bunch of threads on this circle.

[Tyson]

No it wasn't obvious, but thanks for now clearly making it so even a "douche" can see. Well then I guess there might be plenty other OB systems with "punch and impact", including Linkwitz based ones. It's just that in your opinion, there are none you've heard.

Correct.

But of course I can only speak about the speakers I've actually heard.  That's a bit of a truism, isn't it?  I mean the opposite would be akin to saying "The Servo OB bass is the best I've ever heard, and that applies to all speakers in existence.  Even the ones I haven't heard.  ESPECIALLY the ones I've haven't heard!"

Hahaha.

[Russell Dawkins]

It seems the discussion focus has narrowed to low frequencies now?  SL's preference (and the OP's original comment) regarding open-baffles is not just for bass frequencies.

Then what frequencies does SL consider key? I consider lower midrange and bass (~300 Hz on down) to be the most affected by re-radiation, which I also consider to be the most serious liability of box enclosures—the muddying of the sound by re-radiation through the cone. Frequencies from approximately 300 Hz and up are more easily absorbed more or less completely and don't require much enclosure volume, so are much less of a problem in my experience.

I've been experimenting with dipoles since around 1973 and sometime around then I read some designer's notion that the sonic advantage of open baffles increased as the frequency lowered. At the time I was taken aback by the notion, but the more I've thought about it since, the more sense it makes to me.

I've talked to SL numerous times about this.  He considers the open-baffle approach inherently robust and superior to boxes.  Even efforts that are butchered by designers with minimal skills can/will sound halfway decent.  The radiation pattern is inherently superior....there are no box issues like re-radiation, stored-energy....they're generally much cheaper to construct....etc....etc....etc.

Dave.

At this stage it's only mildly interesting to me that I get no response from anyone to the meat of my earlier post.

[Tyson]

I agree with you Russel!  Not to mention how much easier it is to integrate OB bass into a room.  You still have to deal with front to rear and top to bottom resonances, but the side wall resonances are ameliorated. 

I think the observation about the easier nature of getting good bass in the speaker itself also applies just as much to the production of bass in the room.  OB's just have an advantage here. Part of the reason that OB bass is so musical (IMO) is because the room does not obscure it as much as it does with box bass.

[AJinFLA]

I also think a large part of that is due to the way bass response is measured, particularly not taking into account the settling time of the system in response to signals at various frequencies through the range.

In other words, two speakers that measured identically flat right through the range of, say, 200 Hz on down when fed by a slow sweep might sound very different through that same range when fed a music signal, due to the slower settling time of one compared to the other; the one with the slower settling time sounding louder, and perhaps more 'impactful'.

How are you defining "settling time" and its relation to audibility?

[AJinFLA]

I guess you could consider the 15" woofers and the servos sub woofers

Yep.

[AJinFLA]

I consider lower midrange and bass (~300 Hz on down) to be the most affected by re-radiation, which I also consider to be the most serious liability of box enclosures—the muddying of the sound by re-radiation through the cone. Frequencies from approximately 300 Hz and up are more easily absorbed more or less completely and don't require much enclosure volume, so are much less of a problem in my experience.

How do you separate that from the 6db less power/excitation and decay of room modes, when you observed? Was the listening done outside?

[Russell Dawkins]

How do you separate that from the 6db less power/excitation and decay of room modes, when you observed? Was the listening done outside?

The listening was done inside, in the near field when appropriate. It's not at all difficult to separate the sound of the internal box noise re-radiated through the cone from the sound of the room acoustic. They are very different sounds indeed. PM if you want more details, as this involves some proprietary and hard-won information.

[Russell Dawkins]

How are you defining "settling time" and its relation to audibility?

Any sonic imprint added to the signal will of course be audible and every speaker has one. It's partly a question of degree and partly one of the nature of the imprint. As with amplifiers, even order harmonics are relatively benign.

I have never attempted a definition of settling time, but here goes: "the time taken by the driver or the system (driver and box or panel) to stop generating acoustic output once the input signal stops".

In an ideal transducer, whether microphone or loudspeaker, settling time and its inverse—rise time—would be instantaneous. In an imperfect world we have to be satisfied with 'quick'.

It could be measured in terms like room reverb time—R60—where the time for the reverberation in the room to drop to 60dB below the triggering impulse is measured in fractions of a second.

Years ago I cleverly (not!) named my speakers "Quiet Speakers" in deference to this target characteristic. The idea that a good speaker would be quiet—ideally silent—in terms of producing no sound of its own in the process of converting the input electrical signal to acoustic output.

In Europe they sometimes include a revealing  multitone-graph which displays the amount of noise generated by the speaker (intermodulation distortion) quite clearly, when fed by multiple discrete tones. Here's an example from this page (click on 'Intermodulation Distortion'):
http://www.neumann-kh-line.com/neumann-kh/home_en.nsf/root/prof-monitoring_knowledge_glossary_measurement



I think this is a revealing measurement and should be as important as a waterfall plot in aiding visualization of a speaker's distortion characteristic. I'd like to see this included in Stereophile's measurements, for example.

[rabbit]

I have listen various top money famous loudspeakers big and small in rich people homes and all they sound sterile due xover presence and have a poor 2D soundstage due driver is working inside a box.
Even so I still had to tell the proud host> Wow these your speakers are wonderful

people need to stop believing in this stuff, i also did years ago. the absolute worst speaker is one consisting of a fullrange driver, polarresponse will be terrible and distortion goes thru the roof. + phase issues and...well virtually all problems you can get in a speaker = obvious coloration.
its not really an oppinion, its a scientific fact. would you use tweeters as woofers? no, you shouldnt use woofers as tweeters either. long wavelenghts = large cones and some excurtion, small wavelenghts = tweeters.
a crossover does not color the sound when its done correctly

[JohnR]

In Europe they sometimes include a revealing  multitone-graph which displays the amount of noise generated by the speaker (intermodulation distortion) quite clearly, when fed by multiple discrete tones. Here's an example from this page (click on 'Intermodulation Distortion'):
http://www.neumann-kh-line.com/neumann-kh/home_en.nsf/root/prof-monitoring_knowledge_glossary_measurement

Gosh, that seems like rather a severe test but also quite revealing (per the Neumann measurements at the link)!

[Russell Dawkins]

Gosh, that seems like rather a severe test but also quite revealing (per the Neumann measurements at the link)!

Yes, and since the frequency response characteristic is also displayed by inference (the curve implied by the tops of the individual tones) if I had to choose one graph by which to judge a speaker without hearing it, this might be it.

[Tyson]

I have never attempted a definition of settling time, but here goes: "the time taken by the driver or the system (driver and box or panel) to stop generating acoustic output once the input signal stops".

In an ideal transducer, whether microphone or loudspeaker, settling time and its inverse—rise time—would be instantaneous. In an imperfect world we have to be satisfied with 'quick'.

Hmm, so is this why planar drivers sound so much cleaner and more detailed than cone drivers?  Not because the material is "lighter and thinner", but because there's magnets at the front and back of the driver so it's physically started and stopped more quickly/precisely?