The best Dipoles, Dipoles that can do bass?

Zero000

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Infinite Baffle - a word of warning about a Bohne setup.

My listening room is 35 by 14 feet. Not good for the Bohne system. I think 30 by 35 would be excellent. That way there's plenty of space for the side placement of the subs to give you the genuinely impressive sense of scale I heard.

Divas and subs. Those subs will need to cut in low. My guess is you won't like it. The only way to really learn this is to try it.
 

Duke LeJeune

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My listening room is 35 by 14 feet. Not good for the Bohne system. I think 30 by 35 would be excellent. That way there's plenty of space for the side placement of the subs to give you the genuinely impressive sense of scale I heard.

Did you get to try a Bohne system in your room? If so, can you describe your experience? I recall that they really impressed you in Munich.
 
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pjwd

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Since the topic of subwoofers and dipoles and speed has come up, I hope you all don't mind if I share some alternative views. Consider this to be opinion, and take it with a grain of salt because I'm commercially invested in these ideas.

TLDR version: Dipoles sound faster in the bass region because they have better room-interaction behavior than monopoles, but multiple monopole bass sources used intelligently can match the subjective "speed" of dipoles.

Too long version: "Speed" in the bass region is dominated by the in-room frequency response. At low frequencies speakers + room = a "minimum phase" system (according to Toole and Welti and Geddes and probably others), which means that the frequency response tracks the time-domain response. An in-room frequency response peak sounds "slow", and it is, in the sense that it literally takes longer to decay into inaudibility. The good news is, in the bass region when we fix the frequency response, we have simultaneously fixed the time-domain response (and vice-versa).

The problem at low frequencies is NOT that we have too many peaks and dips - it is that we have TOO FEW. Higher up the spectrum the peaks and dips from reflections are bunched together so tightly that they form a continuum (as far as the ear is concerned), but at low frequencies the peaks and dips are far enough apart that the ear picks up on them, and the peaks in particular stick out like sore thumbs. The ear tends to average out loudness over bands roughly 1/3 octave wide, but if the in-room peaks and dips are further apart than this (as tends to be the case in the bass region), then the ear's "averaging" mechanism cannot help us. (The larger the room the denser the modal patterns in the bass region, thus the more numerous and closer together the room-induced peaks and dips, which results in "faster" bass despite the longer decay times.)

One of the reasons the in-room bass peaks stick out like sore thumbs is that the ear has a heightened sensitivity to changes in SPL at low frequencies. If you look at a set of equal-loudness curves, you will see that they bunch up south of 100 Hz. This implies that a small change in SPL has a disproportionately large effect on perceived loudness, for instance a change of 5 dB at 30 or 40 Hz can be perceptually comparable to a 10 dB change at 1 kHz! Combine this with the mountains and valleys of typical in-room bass and, yuck. Incidentally, this heightened sensitivity to SPL in the bass region is also why it takes so long to dial in the correct level for your subwoofers - a small change in SPL results in a disproportionate change in perceived loudness.

In contrast to the ear's heightened SPL sensitivity in the bass region, the ear has extremely poor time-domain resolution in the bass region. The ear cannot even DETECT the presence of bass energy from less than one wavelength, and must hear multiple wavelengths to detect the pitch. If you think about how long bass wavelengths are relative to the reflection path lengths in our rooms, you'll see that by the time you hear the bass, the room's effects are all over it. Perceptually there is no "direct sound" in the subwoofer region in home-audio-size listening rooms. Why then do people report significant improvement from dialing in the phase and/or arrival times of their subs? I think they are improving the in-room frequency response. The ear cannot hear normal in-room arrival time differences as such, but it CAN hear in-room frequency response extremely well. (Related to this, research has shown that with an in-room peak in the bass region, which corresponds with "ringing" where the peak is, what the ear actually hears is the response peak rather than the ringing.) I have nothing against synchronizing the arrival times of mains and sub(s), BUT I would not compromise smooth in-room frequency response for arrival time coherence.

I realize that my prioritizing frequency response over arrival time in the bass region is probably counter-intuitive at first glance, but consider this: There is NEVER any arrival time coherence between the equally-loud backwave and frontwave of a dipole, yet dipoles sound exceptionally "fast" in the bass region. If arrival time coherence really was what matters most, then dipoles would sound slower than monopoles in the bass region.

As a general principle, the greater the number of widely-distributed in-room bass sources, the smoother the in-room bass - and this matters because SMOOTH bass is FAST bass. Each will interact with the room differently because it is in a different location, and the sum of these multiple dissimilar curves is smoother than any one alone. And this improved smoothness - speed - tends to hold up throughout the room, rather than being confined to a relatively small sweet-spot area. In fact what we end up with is more numerous but smaller in-room peaks and dips, which are closer together, and therefore the ear's averaging mechanism is more likely to come into play.

A word about other techniques for smoothing the in-room bass: EQ is great, but if you're EQing a single sub, the EQ will tend to only be beneficial in a relatively small sweet-spot area. Outside of that area EQ will tend to make the response worse, as the in-room peaks and dips will have shifted in frequency such that the EQ is boosting and cutting the wrong regions. Bass traps are also great, and primarily work in the time domain by reducing the decay times. This shows up as an improvement in the frequency response, as would be expected for a minimum-phase system.

In general, whatever you do that improves the in-room frequency response in the bass region pays disproportionately large dividends, whether it be adjusting placements or dialing in the controls or EQ or bass trapping or multi-subbing or combinations or whatever. The ear's heightened sensitivity to changes in SPL in the bass region makes small improvements more audible than one would expect from eyeballing before-and-after curves. Incidentally EQ works really well with a distributed multi-sub system, as the bass response is much more similar throughout the room so EQing a problem is probably addressing a problem that exists throughout the room.

Okay, now let's finally talk about dipoles specifically. You can think of a dipole as two monopoles, back-to-back, separated in PHASE (by 180 degrees) rather than in PHYSICAL DISTANCE. And as this model would suggest, a dipole has smoother (i.e. "faster") in-room bass than does a monopole. This is why most people who try to integrate a single sub with a pair of dipoles can hear too much of a discontinuity and usually get rid of the sub (or only use it for movies). And this is why maybe half of the people who try two subs with their dipoles do end up keeping them - the discontinuity is significantly less.

(When I designed a subwoofer system specifically to "keep up with" dipoles, I went with four monopole subs, as they can approximate the in-room smoothness of two dipoles. And in fifteen years of doing this, I've had zero returns... i.e. the concept seems to work. A distributed multi-sub system can be implemented with a wide variety of subwoofers, not just mine.)

So, finally getting back to @infinitely baffled's situation, he has four subs if I understand correctly. I don't know how they are set up, but he has what it takes to "keep up with" dipole main speakers. The place where ime dipoles may fall short of his Stellas is in impact. A good big dipole just does not convey the physical sensation of impact that a good big monopole does, and I think this is because the net in-room pressure sums to zero with a dipole, but not with a monopole.

Imo, ime, ymmv, etc.
Great post Duke
I am assuming if the room does not "leak" bass you still need to reduce reverb time with traps to get "fast" bass even when using multiple subs and reducing peaks and nulls.
Or in your experience does the flattening of the fr response and consequent reduction of "peaky" reverb make this less of an issue
Phil
 
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infinitely baffled

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Did you consider the SMC Interocitor transformer designed by Steve McCormack? I bought one to use with the cj premier 350, a friend borrowed it and never returned it - although he paid me for it, surely! See:

https://www.whatsbestforum.com/threads/rmaf-the-interocitor-saved-my-life.4248/
No i did not. I wasn't aware of such an off-the-shelf solution.
On advice of Rich Maez at Boulder, we rebuilt my balanced cable to connect into rca inputs.

Would the same device better adapt the pseudo balanced output of the Wavac pre to the Boulder power amp?
I will read the thread and report back.

Much obliged microstrip
 

Duke LeJeune

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Great post Duke
I am assuming if the room does not "leak" bass you still need to reduce reverb time with traps to get "fast" bass even when using multiple subs and reducing peaks and nulls.
Or in your experience does the flattening of the fr response and consequent reduction of "peaky" reverb make this less of an issue
Phil

Thank you, and excellent question.

Bass trapping tends to be far more effective at upper bass wavelengths than at typical subwoofer-region wavelengths.

The more reflective (less "leaky") a room is at very low frequencies, the less energy needed from the subwoofers down there in order to end up with "flat" response. So imo the more cost-effective solution would be to adjust the response of the subs accordingly.

I'm not convinced that decay times in and of themselves are normally a critical factor in the bass region. Note that the larger the room the longer the decay time, BUT in general the "faster" and "more natural" the bass. (If decay times were critical, the opposite would be true.) Imo this is because the denser modal patterns in larger rooms result in smoother frequency response. And imo it is the in-room frequency response which consistently dominates our perception in the bass region.

Perhaps there are unusual situations where the general principle of "fix the frequency response and you have fixed the time-domain response, and vice-versa" do not apply in the bass region, but I have yet to encounter such.

[self-promotional plug] I have at least one customer who spent well over twice the price of my Swarm system on bass trapping and then when the Swarm was installed the improvement was allegedly much greater than what the bass trapping had contributed. And here is acoustician Matthew Poes on the subject of bass traps compared with a distributed multi-sub system. Note that he MAKES MONEY by specifying and installing bass traps, NOT by selling subwoofers. He gets his point across in about forty-five seconds from where the clip should start:


[/plug]

Imo bass traps, multiple subs, EQ - these things can all be on the same team; it's NOT necessarily either/or.
 
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infinitely baffled

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We have similar but not identical approaches. I also prefer that the mains receive a full-range signal, as otherwise I'd have to put something in their signal path to roll off their bottom end, which I'd rather not do. I prefer the mains to naturally roll off between 60 and 80 Hz, as imo the distributed multiple subs I use do a better job up there, mostly for reasons described in my TLDR post above, but also because of the ability to manipulate the phase in that region to enhance spaciousness if your subs have continuously-variable phase controls (more on this if you'd like).

The first part I'm with you 100%, adding something uneccessary into the signal path is undesirable .
But as for crossing over to the subs above 40hz, because i have big speakers with excellent bass, they still sound better down to that frequency. Having even the very musical Velodynes playing above 40hz gave the impression of the Stella's toes being stepped on, in an area where they excel- that electro-magnetic bass driver really is excellent and needs to be given room to breathe and boogie. The character of the speakers at those frequencies is what i love about them, and that includes their delicate touch combined with stupendous weight

But herein lurks a potential solution to the dilemma of a dipole system with limitless bass, which, as i was walking dogs earlier i realised is what you are suggesting:
that the distributed bass array could be a better partner for dipoles?

Interesting....☺
 
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pjwd

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about forty-five seconds from where the clip should start
LOL
Thanks for saving me 38 min
He makes a good point
I wonder how many rooms retain bass down really low.. if there are windows ( not double glazed or fancy laminated ) your going to have a lot of low fr energy escaping
There is no one size fits all solution to acoustics sadly
 

pjwd

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The first part I'm with you 100%, adding something uneccessary into the signal path is undesirable .
But as for crossing over to the subs above 40hz, because i have big speakers with excellent bass, they still sound better down to that frequency. Having even the very musical Velodynes playing above 40hz gave the impression of the Stella's toes being stepped on, in an area where they excel- that electro-magnetic bass driver really is excellent and needs to be given room to breathe and boogie. The character of the speakers at those frequencies is what i love about them, and that includes their delicate touch combined with stupendous weight

But herein lurks a potential solution to the dilemma of a dipole system with limitless bass, which, as i was walking dogs earlier i realised is what you are suggesting:
that the distributed bass array could be a better partner for dipoles?

Interesting....☺
Here is something I am trying for dipole bass ... should have it running in 3 - 4 months and will let you know how it goes .. doubt that it will get chest thumping bass but as there is 4 of them I will be able to swarm them if needed IMAG2065.jpg

They will have 2 x 15" tempest X drivers in each and be shelved via a digital filter
Dipole peak is 170hz and i think the equivalent level of mid / tweeter is about 80db so there is a bit of headroom ... the red is sub and green is woofer woofer and sub.gif
 

Ron Resnick

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Here is something I am trying for dipole bass ... should have it running in 3 - 4 months and will let you know how it goes .. doubt that it will get chest thumping bass but as there is 4 of them I will be able to swarm them if needed View attachment 80023

They will have 2 x 15" tempest X drivers in each and be shelved via a digital filter
Dipole peak is 170hz and i think the equivalent level of mid / tweeter is about 80db so there is a bit of headroom ... the red is sub and green is woofer View attachment 80024

Dual 15" drivers X 4 works for me!
 

Zero000

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Did you get to try a Bohne system in your room? If so, can you describe your experience? I recall that they really impressed you in Munich.
At Munich they were like an antidote to many rooms responding entirely to user requests including mine and playing at good volume levels.

There aren't many rooms that have the confidence/balls to do that.

In another room, the Pnoe made a surprisingly good job of playing Unfolding by Etherwood. This track is seriously challenging in that it has some inherent distortion it it that some speakers make an absolute hash of. The BD driver in the Pnoe made an excellent job of it, tracking it better than my Apogees manage. That is a world class driver, unless it lives in an AxJet, where it sounds dreadful. A high risk driver for sure. If you don't get it right elsewhere in the parameters that are important for it to do well, it's dire. It'll literally rip your ears out.

However, this same track played on the Bohne system couldn't have been more different, really. Bass weight and scale in abundance in a manner the Pnoe could only dream of achieving. More raucous in the mid/treble than the Pnoe from the Bohne Apogee like ribbon, but in a way that sounded very exciting/full of life. These attributes were clear from track to track. I just loved it!

I actually quite liked the Pnoe bass, from what bass it had. It can't do weight/substance, though, sounding far more diffuse/lightweight.

WRT the Bohne system in my room I wouldn't go to the trouble of trying it. I do think it requires a big, wide room to shine. As I said above.

For overall sound quality I would rate my system as better than the Bohne system. But the Bohne system can do things my dipoles have no chance of getting near. And it was just bloody enjoyable for it. Respect is due there:)
 

Addicted to hifi

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Here is something I am trying for dipole bass ... should have it running in 3 - 4 months and will let you know how it goes .. doubt that it will get chest thumping bass but as there is 4 of them I will be able to swarm them if needed View attachment 80023

They will have 2 x 15" tempest X drivers in each and be shelved via a digital filter
Dipole peak is 170hz and i think the equivalent level of mid / tweeter is about 80db so there is a bit of headroom ... the red is sub and green is woofer View attachment 80024
Looking forward to seeing these when they are finished.
 
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Duke LeJeune

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The first part I'm with you 100%, adding something uneccessary into the signal path is undesirable

But as for crossing over to the subs above 40hz, because i have big speakers with excellent bass, they still sound better down to that frequency. Having even the very musical Velodynes playing above 40hz gave the impression of the Stella's toes being stepped on, in an area where they excel- that electro-magnetic bass driver really is excellent and needs to be given room to breathe and boogie. The character of the speakers at those frequencies is what i love about them, and that includes their delicate touch combined with stupendous weight.

Hey with totally different systems in totally different rooms we came to similar conclusions only about an octave apart. I can live with that! My subs are deliberately designed to work well up to 80 Hz (they have exceptionally powerful motors for 10" subwoofers which imo helps), but then I lose the region south of 20 Hz.

With your system, your approach preserves a pristine signal path to your mains by not rolling off their low end. Overlapping subs and mains can be brute-forced into working SOMETIMES, by adjusting the phase controls on the sub so that they sum kinda-sorta-outta-phase with the mains and don't thicken that region, and/or by aggressive use of EQ, but I see NO reason to change what is obviously working extremely well for you. It's further up the spectrum that you miss the spaciousness of a dipole, if I understand correctly.

Too bad the big Alons didn't work out, as imo that's arguably a very promising configuration for what you're looking for.

But herein lurks a potential solution to the dilemma of a dipole system with limitless bass, which, as i was walking dogs earlier i realised is what you are suggesting:
that the distributed bass array could be a better partner for dipoles?

Depending on room size and crossover frequency between dipoles and subs, you may or may not benefit significantly from a distributed multisub system.

But I'm skeptical that a dipole system will be able to replicate what your Stellas do well, ESPECIALLY if the "character of [the Stellas] at those frequencies" (presumably just north of your subwoofers) is what you love about them. And I can imagne why; their woofers probably have extremely powerful motors - something vented boxes can easily get away with - and ime woofer motor strength correlates with the perception of impact, assuming the frequency response is good.

If you could add dipole-like behavior to your Stellas without losing any of their performance in the bass through lower mids, might that be worth exploring? [commercial interest disclaimer] This isn't a purely hypothetical question. [/disclaimer]
 
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infinitely baffled

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If you could add dipole-like behavior to your Stellas without losing any of their performance in the bass through lower mids, might that be worth exploring?

Yes, 100%
Dream scenario would be 'Dipole Utopias'☺
 
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infinitely baffled

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No worries. There's a fairly significant game of footie on this side of the puddle, and I've been working with it on in the background☺
 

infinitely baffled

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christoph

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I have heard Stellas. And the much bigger brothers driven by Naim's best and also Vitus I think.

Stellas versus decent Duettas? I reckon Duettas. But I'm biased;)
I fear Gavin's (?) sound volume requirements would kill a Duetta within a day :oops:
 

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