Dipole midbasses?

[Feandil]

Well I've been reading about the advantages to a dipole setup (though I've never heard one to compare)

I plan to purchase a cheap cheap pair of pro audio 12" to make a "test" subwoofer to see if I like Dipole sound

I would, however, like for someone to give me a link to a dipole midbass solution

if it works out and it sounds like everyone boasts, I might make a 8-10 speaker bass array with 10" drivers....

but I've been reading and there are certian baffle design problems with a midbass dipole solution. any calculators or programs to help me figure it out would be appreciated

also is there any set distance between the dipoled woofers and each other?

What's the difference between W-shaped and H-shaped?

I believe H-shaped will not allow for use up to 300 hz like the midbasses would play... so I dunno what I need to accomplish this...

[Paul W]

Jessica,
Dipole mid-bass is quite achievable. Suggest you look up S Linkwitz site...then read through it about three times He has excellent reference material there, including a baffle calculator.
Paul

My dipoles

[ScottG]

http://www.t-linespeakers.org/downloads.html

most solutions require active eq. - some drivers however (if they are sufficently eff. in comparison to the pairing midrange) can work with a "mechanical" eq. via a high Qts.

I haven't had time to play with mine yet, but these are the drivers I selected for just this solution (2*16ohm per side):

http://store.steelsound.com/Detail.bok?no=478

specs here:

http://madisonspeakers.netfirms.com/rawdrivers.htm

as to IF they meet specs and are suitable for this application - well maybe you'll get there b4 me.

[Feandil]

His explanation seems rather poor...

and I couldn't find any calculators...

he shows you how to build a dipole but no info on a dipole past 100 hz...

when he takes his dipole outside the response after 100 hz is terrible... I would need that flat reponse to 300 hz or more...

I understand how to make the dipole H-shape etc... but I don't understand in a W-shape or some shape how to create the baffle to work up to 300hz

[Feandil]

Originally posted by ScottG
http://www.t-linespeakers.org/downloads.html

most solutions require active eq. - some drivers however (if they are sufficently eff. in comparison to the pairing midrange) can work with a "mechanical" eq. via a high Qts.

I haven't had time to play with mine yet, but these are the drivers I selected for just this solution (2*16ohm per side):

http://store.steelsound.com/Detail.bok?no=478

specs here:

http://madisonspeakers.netfirms.com/rawdrivers.htm

as to IF they meet specs and are suitable for this application - well maybe you'll get there b4 me.

those drivers are very impressive... tell me what you think of them

I would like to do 16 10" midbasses per tower or 8 15" midbasses in a dipole... and those knights look good especially the price

I've seen dipoles in a push-pull pattern... any info on this??? also the classic w-shaped...

I don't really understand how you calculate the distance between drivers in the w-shaped... and the distance to the ends

[ScottG]

SL's is quite "technical" and you realy have to read it numerous times b4 the info really starts to make sense.. that said, most of his information is with regard to active eq. - NOT an acoustic solution.

In particular he DESIRES dipole operation (its cancelation effects) up to 300 Hz + (which is covered by the main panel in the phoenix - NOT by the subwoofer).

In this instance you want a solution that is quite different - a dedicated midbass driver to handle freq.s from about 55 Hz to 300 Hz (correct?). If so then you don't want a "baffle" per se. or rather you don't want anything more than to mount the midbass drivers too. (i.e. don't concern yourself with "W", "H", or "U" channel loading).

(Note that you will still need a subwoofer solution for freq.s below the bandpass mentioned.)

[454Casull]

Originally posted by JessicaG
His explanation seems rather poor...

and I couldn't find any calculators...

he shows you how to build a dipole but no info on a dipole past 100 hz...

when he takes his dipole outside the response after 100 hz is terrible... I would need that flat reponse to 300 hz or more...

I understand how to make the dipole H-shape etc... but I don't understand in a W-shape or some shape how to create the baffle to work up to 300hz

http://www.linkwitzlab.com/images/graphics/p9.gif

Dipole Scan-Speak drivers with a Scan-Speak 9800 tweeter. The crossover points are 100Hz and 1400Hz.

[Feandil]

Originally posted by ScottG
SL's is quite "technical" and you realy have to read it numerous times b4 the info really starts to make sense.. that said, most of his information is with regard to active eq. - NOT an acoustic solution.

In particular he DESIRES dipole operation (its cancelation effects) up to 300 Hz + (which is covered by the main panel in the phoenix - NOT by the subwoofer).

In this instance you want a solution that is quite different - a dedicated midbass driver to handle freq.s from about 55 Hz to 300 Hz (correct?). If so then you don't want a "baffle" per se. or rather you don't want anything more than to mount the midbass drivers too. (i.e. don't concern yourself with "W", "H", or "U" channel loading).

(Note that you will still need a subwoofer solution for freq.s below the bandpass mentioned.)

right I understand the subwoofer thing

I don't understand how you can make a main panel act like a dipole... his explaniation isn't very good and his drawings aren't good either....

I see from the first posters dipole that he just mounted them to the front baffle and that was it... but all the dipoles I've seen are push pull or some thing like that so I don't understand how that would work....

either way... I'm still trying to understand this lintwitz page

[ScottG]

Originally posted by JessicaG


those drivers are very impressive... tell me what you think of them

I would like to do 16 10" midbasses per tower or 8 15" midbasses in a dipole... and those knights look good especially the price

I've seen dipoles in a push-pull pattern... any info on this??? also the classic w-shaped...

I don't really understand how you calculate the distance between drivers in the w-shaped... and the distance to the ends

they appear well made, but require EXTENSIVE break-in to "loosen-up" the surrounds - any measurement taken under at least 300 hours of dynamic playback would be erronius.

I thought I heard some buzzing comming from the surround on one of the drivers during a very heavy bass track - but I could have been mistaken (in any case the remedy is fairly easy - rubber cement in the appropriate area). They are quite dynamic for your average dipole solution (in large measure due to the B (of Bl) and the mms for the given operating bandwidth), when compared to most other dipole solutions. The trade-off of course is that they don't go as low, but that IS a benefit in a dipole design because of the excursion required.

Again, the baffle configurations are utilized to essentially REMOVE dipole effects for a given freq. - unless I'm mistaken, this is NOT what you are after so you don't need to concern yourself with it (i.e just make a baffle wide enough to support the drivers - no wider).

Push-pull is used to cancel distortion as freq. decreases. You could incorperate this opperation in several different manners. You could even do this so that the driver becomes MORE directional and approaches a 2nd order gradient.

Moreover IF you wanted to do this and extened the response of the driver you could:

Operate the drivers in phase but with their magnets back to back. The front facing driver will be facing the listener. The rear driver will "face" into a T-line.

[Feandil]

Originally posted by ScottG



they appear well made, but require EXTENSIVE break-in to "loosen-up" the surrounds - any measurement taken under at least 300 hours of dynamic playback would be erronius.

I thought I heard some buzzing comming from the surround on one of the drivers during a very heavy bass track - but I could have been mistaken (in any case the remedy is fairly easy - rubber cement in the appropriate area). They are quite dynamic for your average dipole solution (in large measure due to the B (of Bl) and the mms for the given operating bandwidth), when compared to most other dipole solutions. The trade-off of course is that they don't go as low, but that IS a benefit in a dipole design because of the excursion required.

Again, the baffle configurations are utilized to essentially REMOVE dipole effects for a given freq. - unless I'm mistaken, this is NOT what you are after so you don't need to concern yourself with it (i.e just make a baffle wide enough to support the drivers - no wider).

Push-pull is used to cancel distortion as freq. decreases. You could incorperate this opperation in several different manners. You could even do this so that the driver becomes MORE directional and approaches a 2nd order gradient.

Moreover IF you wanted to do this and extened the response of the driver you could:

Operate the drivers in phase but with their magnets back to back. The front facing driver will be facing the listener. The rear driver will "face" into a T-line.

What kind of transmission line???

I would like to operate this dipole midbass towers to 55 hz or so... maybe to 40 if possible

I'm unsure what you mean about the t-line though....

What I see a lot with dipole towers is:

Front of driver>>>>>>>> opening out <<<<<<<<front of other driver

would this be what I would do??? :unsure:

and about those knights... that seems like a massive amount of break in time... that makes me question the quality