Backman's paper about mode excitation of different woofer radiation patterns is classic, but there are yher aspects to consider too. Psychoacoustics, spl requiremennt, power requirement, size restraint etc.
Using a monopole sub and OB woofer is wise compromise IMO. We have commercial and diy speakers made that way. With skill, dsp and outdoor measurements it's possible to have cardioid pattern in the very difficult (first reflectionwise) 100-300Hz range.
Using a monopole sub and OB woofer is wise compromise IMO. We have commercial and diy speakers made that way. With skill, dsp and outdoor measurements it's possible to have cardioid pattern in the very difficult (first reflectionwise) 100-300Hz range.
If you look here, there are two examples with a closed subs:
https://www.linkwitzlab.com/LX521/PhotoGallery.htm
Thanks again for the lively discussion. Lots of food for thought.
Whoa - 224 pages! That's a daunting read and will keep me busy for a while.
That actually looks quite promising.
Therein lies the crux. While I'm generally crafty, I'm a casual hobbyist and have never built a speaker let alone a XO before. I'd be happy to pay 1/10th of the price, but I don't have the knowledge and experience to make that happen and until this hypothetical speaker at 1/10 of the price is available as a kit or at least as a detailed plan and parts list, people like me will have to pay more. In that regard, I feel, the LX521 kit (or its open baffle part only) provides a good compromise between performance, feasibility and price.
As others have pointed out you can definently build a good dipole on a budget.
The LX521 uses very well build and very expensive woofers to achieve a very high output in a relatively small package. If you can accept say half the xmax or 3 dB in reduced low end output, price goes down by a lot. You can also usually reduce price by going with a slightly bigger woofer since they can get away with cheaper magnets, as they don't have to be pushed as hard to reach the same output due to more surface area vs smaller woofer.
The LX521 uses very well build and very expensive woofers to achieve a very high output in a relatively small package. If you can accept say half the xmax or 3 dB in reduced low end output, price goes down by a lot. You can also usually reduce price by going with a slightly bigger woofer since they can get away with cheaper magnets, as they don't have to be pushed as hard to reach the same output due to more surface area vs smaller woofer.
Both those used stereo subs, at least, which is sensible given the 120 Hz crossover. And one of them wasn't very happy with the outcome. (I know, because I bought the LX521 drivers from him when he dismantled them.)
Have you looked into the LX521 kit options? You'll need the plans/license too. If you add in the cost of a miniDSP Flex 8, your getting close to $2000. That's quite a bit, when you're planning to throw a part of SL's design out the window, turning it into a 2.1 sub/sat setup,
As others have said above, there can be a place for sealed subs with open baffle. (Siegfried himself designed the Thor sealed sub for use with the Orion.) But crossing a single sub at 120 Hz to the LX521 mid/treble baffle sounds like a poor plan to me.
Looking at the price of the LX521 option, I hadn't realised those Seas L26RO4Y woofer were so expensive now - $1800 for the four is a lot!
Here's a thought: if I were thinking of building the LX521 and needed to keep the budget tight, I'd be tempted to use the old Peerless/Tymphany XLS drivers that were used originally in the Orions. They're a third of the price of the Seas ones, and are still available from a few places.
They did very well in the Orions, and when Siegfried changed over to the Seas units, I don't think any alteration to the equalisation was required. The main benefit, if I remember correctly, was that the XLS units could hit their mechanical limits sometimes, and the Seas units were better at avoiding that. But that is probably only an problem with HT, not music.
Here's a thought: if I were thinking of building the LX521 and needed to keep the budget tight, I'd be tempted to use the old Peerless/Tymphany XLS drivers that were used originally in the Orions. They're a third of the price of the Seas ones, and are still available from a few places.
They did very well in the Orions, and when Siegfried changed over to the Seas units, I don't think any alteration to the equalisation was required. The main benefit, if I remember correctly, was that the XLS units could hit their mechanical limits sometimes, and the Seas units were better at avoiding that. But that is probably only an problem with HT, not music.
