Suggestions of using dipole subs with electrostats?

[AW]

Hi,
I have a pair of dipole subs based on the concepts shown in the Linkwitz webpage:

http://www.linkwitzlab.com/woofer.htm

but have never been able to get them sounding really good with my Acoustate Spectra 11 panels - or even close to as good as - let alone better than - sealed box subs.

The rom is not large (circa 20 sq. meters/200sq.ft) and the ststa sound great by themselves (their woofers long since tossed) but the closed box subs really help the low end and I'd like to gain the adnvantages the dipole subs should provide.

I've moved them all over the room - and played with all sorts of crossover points and slopes...

That the closed subs work well indicates it's not a basic room problem.

Any hands on experiences you''d care to share?

Allen

[MJ Dijkstra]

Hi,

Did you try putting the dipole subs in a large room?
They need room to breath.

[Bazukaz]

These dipole woofers require electronic equalisation.I would better go with a sealed system instead - it does not have dipole cancellation.
To avoid this cancellation , dipole sub must have very long transmission line of around few meters.For sure , a lot depends on driver you are using.

[Calvin]

Hi,

dipole subs, build right should be the best compagnion for an ESL.
Though SL provides lot of information about dipole-subs his subs are imo not the best concepts.
use the right drivers. One of the best is the SLS10 of Peerless. The XLS-series is too low in Q-factor and too expensive
use passive equalization for the notch filter. It always gave better results than active eq.
build symmetrical. SL´s design are not! Both drivers experience different working conditions.
build very small. The Fs drops more and it looks much prettier.
use active eq only to boost the lowest freqs if necessary

jauu
Calvin

[AW]

Thanks for the answers - bt putting the subs in a larger room is not going to help - that's the room I have and they need to work in.

Clavin,
>dipole subs, build right should be the best compagnion for an ESL<

In theory - yes.
.
Though SL provides lot of information about dipole-subs his subs are imo not the best concepts<

Can you link me to what you feel is better?

What is the speaker in the Pix you attached?
.
>use the right drivers. One of the best is the SLS10 of Peerless. The XLS-series is too low in Q-factor and too expensive<

I agree on the 'expensive" point for sure!

>use passive equalization for the notch filter<

DO you mean "notch" or "roll off" filter?

> It always gave better results than active eq<

OK, any reason why this is so?

>build symmetrical. SL´s design are not! Both drivers experience different working conditions<

Makes sense.

>build very small. The Fs drops more and it looks much prettier<

Pretty I understand but the idea that the FS is lower with a small box/cone? I don't understand this part at all...

>use active eq only to boost the lowest freqs if necessary<

OK. Passive makes them more universal for sure.

Very interested, Allen

[Calvin]

Hi Allen,

for some years now I´m using as well as building dipole-subs using the principles of AudioElevation of Germany. This subs were tested with remarkable success in Stereo and Stereoplay, even though in the latter case they never ordered any advertisement They built afaik the smallest dipole subs. One reason to build small is that the free air resonance sinks when built in (and this effect gets stronger with smaller volumes of the cavities). So it´s ideal to use drivers whose fs is between 25 and 35Hz (10" to 15")
The passive eq filters the first peak with an RLC-parallel-Notch, accompanied by a series inductance with high ohmic value (It´s not intended as Lowpass in first case, but as the working impedance for the notch and it filters noise coming from an amp) The roll off above app. 100Hz is done by the active Filter of an sub-amp module. So they are active subs featuring passive equalizing (just the notch). Experience showed that this solution almost always played better than completely actively filtered solutions. Don´t know why, but that´s our experience.

jauu
Calvin

[gnnett]

Hi Calvin

Like Allen I am looking for a sub to match a single Acoustat panel. Not sure where Allen needs the Sub to start with his Spectra panels, but I was targetting under 100Hz.

What frequency can this style of dipole sub extend up to and down to for that matter?

Is the small cavity at each face of the dipole acting as a band pass filter?

Does it raise or lower the resonance frequency from the free air resonance?

I suppose I had better order up a set of the SLS drivers before they are disappear like the DLP12 from Adire.

I like what I am hearing here and ended up at the Hobby Hi Fi Web site via the Audioelevation site. As an aside do you know if Hobby Hi Fi have an English version? Looks real interesting.

Kind Regards

Grantn

[Calvin]

Hi,

the upper frequency with this build of dipole-subs is determined by the size. The smaller the higher You may go, but practise showed that 150Hz (12" driver and bigger) -250Hz (8" and 10") are the highest points. This build is meant for subwoofers only.
The lower frequency is determined by the size and the parameters of the driver. In any case the free air resonance of the driver is lowered. In most cases roughly around 5Hz but You can achieve up to 10Hz.
The effect gets stronger with smaller chambers, but You have to compromise because a too small chamber leads to compression losses and -noises. The SLS-Series (8", 10" and 12") are near perfect drivers for this kind of build because they have Fs beteween 30-40Hz which is lowered in a small chambered dipole to ~20-30Hz. They have a progressive longthrow suspension, so You can´t destroy them even under these free-air working conditions. And best of all...the Qts is around 0.5 which allows for many rooms to be played in without any bass-equing (passive solutions possible). With a quad of 10"-drivers for each channel You have enough power for even big rooms and high sondpressure levels. With these 10"-drivers You´ll reach down to app. 25Hz with much better resolution and detail than with any other concept of this driver and volume class.
Another sub I built using one single 18" driver, the resonance dropped from 21Hz free air to 12.5Hz built in. But this low resonance is not useful in no way. So look for drivers between 25-35Hz Fs together with a higher Q (even Q >1.0 is ok!!)

jauu
Calvin

[ErikdeBest]

Very, very interesting thread

Calvin, are you talking about the 'ripole' concept?
Ripoles - Honey, I shrunk the dipoles! #1
What you are describing and what I've read about ripoles match in most aspects - and I am very interested in them.

I bought myself 4 18inch subwoofers with a Fs of 29Hz, a Qts of 0,6 (omnitronic AL-1800). My plans are to build a W subwoofer a la linkwitz (I actually am halfway the work) but now I read again that with this concept I can lower the Fs by some 5Hz, which would be very nice. The compact building is also very appealing...

Besides for myself I am also thinking about a good sounding system for the sister of my girlfriend. She studies music and needs some decent audio system... My idea is to buy two or four 10" car subwoofers (there are millions of cheap subwoofers with a Fs of around 30Hz and Qts of 0,5 or more) and build ripoles from them, which will serve as a stand for a small open baffle with a fullrange unit. The crossover point will than be around 250Hz...I won't need a big baffle to reach 250Hz... Well, just plans, but what do you think?

Many thanks

Erik

[Calvin]

Hi,

ripole is a term that I hardly ever use, because it is not Axels creation.
The subs were mearketed under BMC Attac and DRS. The first used for the commercial products build symmetrical with at least 2 drivers facing each other and sold under the Label AudioElevation, the second build asymmetrical with only one driver and used for DIY-purposes. This one was described in HobbyHifi. So I stay with the original terms.

Well over the years I got many questions like Your´s (and I know Axel got the same): "I´ve just a couple of drivers left and I want.....otherwise I´d drop them, because they can´t be used to any good anyway"
Please don´t be upset, but even with a lot of years of experience I just don´t know each and every driver on the market and there´s more to successful dipole building than just size, fs and Qts. One thing I can say is, that I still have to come across a car-sub-driver that is ok for a good dipole-sub. One more thing I can say is, that with this style of designing a sub, success will be missing very probabely.
As with any other project design carefully and use good material.
If You need help feel free to ask. But keep in mind, that a complete and sensible set of TSPs is much more worth than just a brand name.

jauu
Calvin