All kinds of things are getting scrambled in their sequence, compared with recent plans; this is just one more... in this case, I'll put the responsibility on the shoulders of an HT Guide member from Singapore who has strong interest in building something like the Isiris three way design study. And this was on my moderately near term list of to-do's, so it got pushed forward a bit.
Let's summarize some issues:
Running the numbers looks pretty good in the same sealed enclosure- and of course could easily be improved with even just a modest 3dB Linkwitz Transform:
So, what are we waiting for, other than 4 drivers from PE?
I'm going through the archives, and pulling out the stuff that could constitute a build guide, and updating the CAD drawings to add Metric values and clarify a few points...
This one should move pretty fast... can you say, "Isiris summer camp"?
Let's summarize some issues:
- Like many older designs, component availability may be an issue- in this case, the new builder has recently acquired a pair of Jantzen JDT0-1024, so scratch that issue off the list.
- The Accuton C173-6-090 is still the best part to consider for this application out of their entire series of similar drivers, and a review of the data sheets and graphs will show why... and with care, they can still be sourced.
- Aurasound woofers... no way. Long discontinued.
- But that brings us to the option I had been pondering a long time, the conversion to using the Dayton Audio RSS315HFA-8 woofers, connected in parallel. This driver has T/S parameters not all that dissimilar to the NS12-513A, and wiring two 8 ohm drivers in parallel, instead of connecting two four ohm drivers in series, can give a pronounced sensitivity boost, 6-7 dB.
- The RSS315HFA also can deliver 40% greater Xmax, not to be sneezed at.
- Both drivers have their resonant breakup mode near 2kHz, and the big Dayton has pretty smooth response out to 1200Hz, making it quite suitable for a 300-400Hz crossover point, given the motor design and modest impedance rise.
- Mechanically, the RSS315 is just slightly larger, but the gods of fate smile upon me, and it fits in the original cabinets OK. Well, an RSS315HF-4 does, and I don't think it's going to be any different in size than the four RSS315HFA-8 winging their way toward me since the middle of last week.
- There was a Test Article 6 crossover developed but not yet built- all the parts are on hand, but obviously some components will need to change, especially the woofer crossover.
Running the numbers looks pretty good in the same sealed enclosure- and of course could easily be improved with even just a modest 3dB Linkwitz Transform:
So, what are we waiting for, other than 4 drivers from PE?
I'm going through the archives, and pulling out the stuff that could constitute a build guide, and updating the CAD drawings to add Metric values and clarify a few points...
This one should move pretty fast... can you say, "Isiris summer camp"?
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