Dipoles ?

Hello

I read www.linkwitzlab.com and my mind is totaly crazy about dipoles [for a long time, to be honest]

I think about making "el cheapo" version of SL Orions.

I read a lot [here and some other "places"] and these are the speakers that I'm thinking of right now:

- 27TDFC (H1189) or 27TBFC (H1212) as tweeter
- 205 WR [830884] driver for mids
- H frame 2x SLS 12" [830669] for bass


Now I'd like to ask some questions:

1. First of all - is that whlole "dipole thing" worth effort ? I don't have lot of money to experiment... I'd like to "build and enjoy". Four drivers for bass - its a lot.
Maybe it is worth more just to buy less but more expensive drivers [to go 2 way with Excel W18 and ScanSpeak 9700 for example] ?

2. Is enybody familiar with new HDS nomex Peerless drivers ?

3. Are those Seas tweeters MUCH worse than SS9700 or Excel Millenium ?

thanks for attention

best regards :)

Lenny
 
Sooo, soooo, soooo worth it!

I don't think I'll build another enclosed loudspeaker for myself ever again. My OB speakers are my third go at DIY and it was the charm alright. I'm planning on using acrylic to make my final design and am anxiously waiting for the summer to do this.

The sound is incredible, clear, articulate and with the right cross-over and drivers (EQ too), you will enter two worlds; Audio Nirvana and the "I love OBs so much that I would...".

From experience you want mainly two things for woofers: High excursion and a low Fs.
 

hobby1

Member
2004-06-11 8:20 am
paris
hi lenny

first,i use the same woofer,they work very well in dipole
for budget purpose,think about use only one woofer in U frame
because efficient is about 92Db plus 6Db for a equal lengh u frame then a H frame.
if your room is not too large it can be sufficient.....
about the 205 WR be sure it can go at about 1.5/2khz to cross tweeter
finally,like bose,i think dipole is far better than any enclosed things,read and apply all Mr Linkwitz's recommendations

greets
 
Only one problem with dipoles: if you make a good job of them, it's unlikely you'll ever be able to listen to a conventional box speaker again. There's no looking back... says me. I had someting vaguly similar to his Phoenix, albeit with full-range units on the main panels, which I had to sell, as it was physically just too big for my listening room. My ML TQWTs and corner horns are great substitutes, but dipoles still haunt my musical dreams.

Don't assume BTW that more expensive automatically means 'better'. In a dipole, you have to have specific requirements, such as very long-throw for the bass drivers. In fact, in my view the primary benefits of dipoles are in the bass-regions, not the midrange, and certainly not the treble (observe that none of Linkwitz designs have dipolar treble... for good reason), as they activate far fewer room-modes. This is rather ironic, because that's where they are hardest to get working due to the acoustic cancellation a low frequencies! Oh well...

Some try a hybrid enclosure -part dipole, part sealed / vented / TL box enclosure. Most use the box for the low-frequencies and open-baffle for the mids and highs -fair enough. Yet, given the choice, and following Linkwitz guidelines, the better bet for optimum hybrid sound would actually seem to be a sealed box for the mids and highs and dipole for the low frequencies!

Dipoles? Do it. You will not regret it.

Best
Scott
 
Scottmoose said:
Only one problem with dipoles: if you make a good job of them, it's unlikely you'll ever be able to listen to a conventional box speaker again.
I accidentally made this same mistake with a pair of midrange speakers leftover from an old set of Cerwin Vega's and a big piece of plywood.

I really like TL design, though, so I don't think I've been completely converted to the dark side yet. Of course, I haven't felt the power of the dark side, either; that's for my OB sub project.

Right after that, THEN I'll do another TL. I swear!

Dave
 
Hmmm...

Having built several dipoles, I have come to the conclusion that cardioid, or sealed box bass has the edge on diple bass.

It really requires tremendous ammounts of EQ to get it right and in a good room, equally flat response can be had with sealed.

The midrange however is where the magic is, especially 150Hz-1000Hz. The lack of 'boxyness' and the problmatic transition from 2pi radiation to 4pi radiation is where the magic happens IMO.

-Paul
 
Same here...

I agree completely with most all of the previous comments, although some comments seem more appropriate for line-source systems than dipoles.

Dipoles lose all the box coloration simply by virture of their design. I eluded to some of this on the "Drivers" page of my project website. Build a sturdy box, and put a boxed speaker inside of it. Crank up the speaker inside and just listen to the box "sing". If the backwave from the driver can vibrate a .75 or 1.0 inch piece of MDF, what can it do to the speaker cone itself?

No box = No Box vibration (noise) and no captured waves coming back through the speaker cone.

IMO, this is effect is most apparent in the critical midrange and upper-midrange from 300 to 5000 cycles. Instruments (particularly keyboards and horns) simply are unveiled by this lack of box noise. Voices are also greatly (incredibly) impacted.

I had great dipoles for a time, then was forced back to boxes. Now, I'll never go back.

Best of luck with your project.


The Ribbon Project
 
First of all -thank you so much for kind comments. I'm surprised how many posts.


Bose(o) said:

From experience you want mainly two things for woofers: High excursion and a low Fs.

That's why I'm afraid about those SLS speakers. They are not that powerfull as XLS. But in the other hand - I can build closed box subwoofer later, for realy low freq.


hobby1 said:

first,i use the same woofer,they work very well in dipole
for budget purpose,think about use only one woofer in U frame

Do you use this speakrer this way ? Is is enough ? Can you tell us what kind of music you like to listen ?
I like very different kinds of music, but I sometimes like to turn Pat Metheny off, go to "wild mode" and play Chemical Brothers. So bass is important.


sreten said:

Thank you for that link.


Scottmoose said:

Don't assume BTW that more expensive automatically means 'better'. In a dipole, you have to have specific requirements, such as very long-throw for the bass drivers.

That's why I think about my "el cheapo Orions" vs "normal" closed [or vented] box with more expensive speakers. If you don't have to buy that many bass units - you can spent more on good 2 way speaker.


Can we now discus more about the speakers that I mentioned ?

Anyone have comments about new HDS Peerless or 27TxFC Seas speakers [comparing to more expensive Excel/Scan Speak ones] ?

best regards

Lenny
 
hi,

"Do you use this speakrer this way ?"
yes,1 sls in U frame per voice and active eq

"Is is enough ?"
yes too...but my room is 18 m2

i listen to all kind of music,from classic to r'n'b (strong tr808 bassdrum) but Mainly live music
and this system is use as monitor in my home studio

the only limitation of the sls is fs (28hz) that it can demand big eq down this freq,but depend of your room too....

in my configuration 3 Db bassboost at 28hz is use and a Brickwall active hipass at 18hz to limit excursion

see the attach file it's comparison of xls and sls made whit "xlbaffle" spreadsheet

hope help you
 

Attachments

  • compar.jpg
    compar.jpg
    71.9 KB · Views: 2,370
It all starts to sound the same after a while, but what the guys above have said sound mostly pretty right to me ... I'd been fussing over enclosures for years - box after box - sealed, BR, TL, voigt pipes, back horns ... Then I built (and here "built" is a relative term) a pair of open baffles - 600 X 1000 mm with 300 mm wings on the sides, with a three way driver configuration, and I couldn't believe it - they sounded so REAL .
Now I am running a 15" bass driver and a Visaton full range (with active Xover and bi amp) in an OB that is simply a sheet of mdf with holes in it ... I still have my horns in my office, but for my main listening I can't see me ever going back to boxes ... this open sound is so good!:D
I don't think you can go wrong with the Linkwitz speakers, and by all accounts the NaOs are pretty amazing too.
Good luck ... keep us posted!
ALF in AUS:)
 

ScottG

Member
2003-02-04 12:23 am
US
PHilgeman said:
Hmmm...

Having built several dipoles, I have come to the conclusion that cardioid, or sealed box bass has the edge on diple bass.

It really requires tremendous ammounts of EQ to get it right and in a good room, equally flat response can be had with sealed.

The midrange however is where the magic is, especially 150Hz-1000Hz. The lack of 'boxyness' and the problmatic transition from 2pi radiation to 4pi radiation is where the magic happens IMO.

-Paul

Yup..

It really has little if anything to do with the radiation, rather its about:

1. resonances
2. resistance
3. compression

1&2 principally corespond with bad sound from 300 Hz up. All 3 however are important from the bass region up to 300 Hz.

There are some generalities however that can be "usefully" attached to the bass-300 Hz range:
1. the lower in freq. you go the less important resistance becomes (i.e. acoustic resistance from fiber fill)
2.the lower in freq. you go the more acoustic compression is usually DESIRED, and it can be advantageous at a lower sp level (than reference - i.e. flat on axis) up through to 300 Hz. For instance a driver that operates in dipole between 60 Hz and 300 Hz at reference level (or slightly less than reference level due to summing), can actually be improved upon by using a secondary driver (in perhaps an acoustic suspension) that covers most of this bandwidth (say up to 100 Hz) but at a lower level (say 6-9 db less). This subjectivly adds back a degree of "punch" that is missing via the dipole approach while minimizing the "forward" "bunched-up" imaging that results from acoustic compression.
 
LennyK said:
do you say, that dipole designs, like Orion for example, lack bass punch?

I haven´t heard Orions, but my own dipoles definitely don´t "punch" as much as most monopole designs. Which I see as an advantage, since "kick bass" in typical rooms seems to be enforced by excitation of room modes in the region from 80-120 Hz. This is a feature dipoles commonly "lack".

That´s IMHO. Would be nice if someone could explain exactly where the "punching" difference between monopoles and dipoles stems from.

Rudolf
 
The room, as you mention. Depends on the room of course, which is why I despise rooms as a pain in the neck, and try to circumvent their influence whenver possible. Most likely a horizontal mode, though in some cases the vertical mode will also come into play, especially if the speakers are near corners.

Below 40Hz dipoles are impractical, so I'd shift to bipolar operation for the subs, which also tend to energise less room-modes than monoples. That 'punch' might be subjectively impressive, but don't forget that it's rarely on the recording. Fair enough if you like it, but remember it's not accurate. Most rock is already tickled up in that range anyway during the mixing.

Beware the assumption of flat responses. It's very easy to get a flat response from both dipoles and monopoles -in an anechoic chamber. The principle advantage of dipolar bass down to 40Hz or so is that it excites far fewer room modes, with the result that you hear your drive-units more, and much less of the room. This is generally a good thing -rooms are far harder to predict, especially at low frequencies, than drive-units, which will almost invariably be better behaved.
 

reins

Member
2004-03-12 7:38 pm
Bayern
Scottmoose said:
s.

Below 40Hz dipoles are impractical, so I'd shift to bipolar operation for the subs, which also tend to energise less room-modes than monoples. That 'punch' might be subjectively impressive, but don't forget that it's rarely on the recording. Fair enough if you like it, but remember it's not accurate. Most rock is already tickled up in that range anyway during the mixing.

[/B]


I have no Problem to get flat response down to 25Hz with my 15" Lambda driver :)

I believe that many people think punch is equal to BOOOOOM. I don't miss the BOOOOM ;)

Stephan
 

reins

Member
2004-03-12 7:38 pm
Bayern
Rudolf said:


In the light of J.Ks examinations regarding dipole response
http://www.musicanddesign.com/roomgain2.html
would you mind stating your room dimensions and fr of the Lambda?
I´m curious to see John´s findings verified in real life.

Thanks
Rudolf

The article describes exactly the behavior in my room:
Room dimensions are 6m x 4m x 2m and below 25Hz is not much response left. I observed the rise in response around 30Hz too. Fs of the driver is around 20Hz.

Stephan