Dipole vs Box speakers

[StigErik]

It's the perspective on the photo that's weird. The red ones have two 18" woofers, two 8" low mids, two 5" upper mids and one 80mm (?) AMT tweeter.
The dipoles have one 18" woofer, one 8" midrange and a 150 mm AMT.

 

[DanielT]

I can only speak for myself here - but here's two very different pair speakers I had in my room 15 years ago. One of them totally blew the other away when it came to pure listening enjoyment. Both were using active crossovers/DSP. Which ones would you vote for? The dark red closed box ones in the rear, or the flimsy pinewood dipoles in front?


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Since we are talking about dipoles here in the thread, I am guessing that they were the ones you said were the ones that totally blew the other away.

Congratulations on cool speakers. Looks really nice!

 

[StigErik]

Yes, one of them blew the other away. The question is - 1) The closed boxed or 2) The dipoles

 

[Blumlein 88]

Yes, one of them blew the other away. The question is - 1) The closed boxed or 2) The dipoles

There is a Japanese concept of a question being too small for the answer. I think this is an example. There is much more involved in which is the better speaker than either CLOSED BOX or DIPOLE. So your question is too small for the truth of the answer. The answer too big. Such answers according to the concept usually point to something outside what the question is considering. Something important is not in the question.

Time to un-ask the question and forget it or try again.

 

[DanielT]

Yes, one of them blew the other away. The question is - 1) The closed boxed or 2) The dipoles

But bass in box speakers with double 18" woofers vs dipole with an 18" woofer, provided they are well constructed and with the same model of woofer, the box speaker must be able to produce lower bass, better bass.

In addition to bass, looking at the entire register, it is probably largely a matter of taste which of the speakers you have that you prefer. If you like the dipole sound, you like them best.

 

[StigErik]

This was more or less a joke question from my side, but anyway - a very simple prototype made from a pinewood board was the start of my love affair with dipoles in general. Of course - both speakers I showed a picture of had it's own strengths and weaknesses. That being said, there were more things wrong with the big closed box towers than the dipoles.

 

[Burning Sounds]

It depends on your point of view and other references I guess. I have heard the LX521, and don't think it has great bass . Yes, it's quite good at low volumes and above 40 Hz or so.

IIRC you have a rather exceptional bass array so I can see why you think the LX521 bass is a bit weak in comparison. But compared to most box speakers the bass of the LX521 is exceptionally good in terms of articulation. I think its limit is about 96dB @30Hz, so not too shabby really, What it won't do is pressurize the room like a closed box speaker and that is important to some people.

I've taken my LX521s to numerous hifi get-togethers in various size rooms and one of the things I've learned is that its bass does need a good solid floor to provide the weight and impact of which it is capable. Put the speakers on a springy wooden floor and you're going to hear the floor and not the speakers.

I do own some (admittedly old) true ribbon Maggies which I still enjoy, but in terms of bass weight, tonality, soundstage and imaging the LX521 is far superior IMO.

 

[StigErik]

I have Maggies as well - 3.7s with active crossovers and DSP (MiniDSP flex) and Hypex amps. The Maggies are absolutely wonderful above 500 Hz, where they have exceptionably low distortion at any reasonable listening level. However... the lower you go in frequency, the more obvious do their shortcomings get.

 

[Burning Sounds]

Quite true!

I originally bought the plans for the LX521s from SL just to build the bass units for my Maggies as I could never get closed box bass to blend to my liking.

It was probably a good 6 months or more before I built the upper baffle and I was quite taken aback at how the speakers just disappeared - the more solid images were just not attached to the baffles at all which is not what I had experienced with the Maggies. Although that could be down to the room, too.

 

[StigErik]

Are you using the original passive crossovers in your Maggies?

I have a Double Bass Array closed box subwoofer system below 80 Hz, and also a dipole mid-bass system the same size as the Maggies with four 12" drivers in it, crossed over to the Maggie bass panel at 550 Hz. And as mentioned before, DSP and active crossover. It's a completely different speaker than an original Magnepan. The worst flaw of the Maggies is the crossover in my opinion. It's really something wrong there.

 

[fpitas]

I did ‘t have LX521 in mind when I said dipoles have little bass. But 4x Seas L26RO4Y (!!!) with DSP to get to 30 hz kind-of proves the point in a way.

With lots of Doppler distortion to go along with the huge cone excursion.

 

[Burning Sounds]

Are you using the original passive crossovers in your Maggies?

I have a Double Bass Array closed box subwoofer system below 80 Hz, and also a dipole mid-bass system the same size as the Maggies with four 12" drivers in it, crossed over to the Maggie bass panel at 550 Hz. And as mentioned before, DSP and active crossover. It's a completely different speaker than an original Magnepan. The worst flaw of the Maggies is the crossover in my opinion. It's really something wrong there.

No, they are active and I also use DSP. They are 2.5Rs so the ribbon goes down to 1kHz. The first 2.5Rs produced used a first order x-over which resulted in quite a few blown ribbons as I understand it. Later models used a 12/18 BW x-over. I use a LR4 which gives the ribbon more protection and sounds fine to me (and measures well in room).

 

[Burning Sounds]

With lots of Doppler distortion to go along with the huge cone excursion.

So what am I hearing from this lots of doppler distortion? In what way does it manifest itself?

 

[fpitas]

So what am I hearing from this lots of doppler distortion? In what way does it manifest itself?

Intermodulation, from the cone movement phase modulating higher frequencies.

Doppler Distortion in loudspeakers

Doppler distortion in loudspeakers - Real or Imaginary?

sound-au.com

 

[jhenderson0107]

Intermodulation, from the cone movement phase modulating higher frequencies.

Doppler Distortion in loudspeakers

Doppler distortion in loudspeakers - Real or Imaginary?

sound-au.com

In rebuttal to your assertion that Doppler distortion (aka PMD) is problematic on the LX-521, the very article that you reference states:

"The effect [Doppler distortion, i.e. PMD] is very small (to the point of being virtually inaudible by itself), and is usually swamped (or masked if you prefer) by amplitude modulation and intermodulation distortion, so could be considered immaterial in any typical loudspeaker system. "

"The methods that may be used to minimise PMD are exactly the same as those used to minimise intermodulation distortion, primarily, reduce the excursion of the mid-bass driver."

"Naturally, a 3-way system will outperform a 2-way in this respect, since the midrange driver's excursion will be minimal with no bass content."

The LX-521 is a four-way system and its 10" drivers cross-over to an 8" lower-midrange driver at ~90 Hz, much, much lower that the frequency used to illustrate the effect within the article. Linkwitz himself addressed the doppler phenomenon on his extensive website. Doppler distortion is practically inaudible and demonstrably below measurement thresholds on the LX-521 bass module. Additionally, these woofers are mechanically isolated from the midrange and tweeter subassembly.

 

[fpitas]

In rebuttal to your assertion that Doppler distortion (aka PMD) is problematic on the LX-521, the very article that you reference states:

"The effect [Doppler distortion, i.e. PMD] is very small (to the point of being virtually inaudible by itself), and is usually swamped (or masked if you prefer) by amplitude modulation and intermodulation distortion, so could be considered immaterial in any typical loudspeaker system. "

"The methods that may be used to minimise PMD are exactly the same as those used to minimise intermodulation distortion, primarily, reduce the excursion of the mid-bass driver."

"Naturally, a 3-way system will outperform a 2-way in this respect, since the midrange driver's excursion will be minimal with no bass content."

The LX-521 is a four-way system and its 10" drivers cross-over to an 8" lower-midrange driver at ~90 Hz, much, much lower that the frequency used to illustrate the effect within the article. Linkwitz himself addressed the doppler phenomenon on his extensive website. Doppler distortion is practically inaudible and demonstrably below measurement thresholds on the LX-521 bass module. Additionally, these woofers are mechanically isolated from the midrange and tweeter subassembly.

I think we were talking in general terms about open-baffle speakers. I'm sure Linkwitz is perfectly aware of Doppler distortion.

 

[Burning Sounds]

I think we were talking in general terms about open-baffle speakers. I'm sure Linkwitz is perfectly aware of Doppler distortion.

No, I don't think you were talking in general terms as you used a quote from @TurtlePaul about the LX521's bass drivers and then raised doppler distortion in the same post linking the two together. A bit disingenuous, no?

But I do thank you for the Rod Elliott link - I hadn't seen that article before and it is very good. He does note in it that SL was very much involved in looking at Doppler distortion and as @jhenderson0107 notes there is a section on Doppler distortion on SL's website.

 

[fpitas]

No, I don't think you were talking in general terms as you used a quote from @TurtlePaul about the LX521's bass drivers and then raised doppler distortion in the same post linking the two together. A bit disingenuous, no?

But I do thank you for the Rod Elliott link - I hadn't seen that article before and it is very good. He does note in it that SL was very much involved in looking at Doppler distortion and as @jhenderson0107 notes there is a section on Doppler distortion on SL's website.

But 4x Seas L26RO4Y (!!!) with DSP to get to 30 hz kind-of proves the point in a way.

 

[fpitas]

I'm through here. Things are too abrasive.

 

[jhenderson0107]

I'm through here. Things are too abrasive.

I did attempt to refute an assertion. I apologize if my reply seemed abrasive.