'Pi4'- JBL 4507 cabs with 2226H drivers. Cabs are tuned to 40Hz with all four ports open. DIY Pi4 crossover.
In my (wisdom?!) I decided on a couple of alterations, and would welcome comments as to whether they may be detrimental to the original design parameters.
Pre-assembly parts
1. Modified JBL waveguide (part #338800-001) on B&C DE250 drivers were used in place of Eminence H290 waveguides. H290 is 90deg X 40deg and JBL is 90deg X 50deg- there was some concern as to whether nodes/crossover design would be affected.
Thread-on section removed. Driver bolted to flanges.
2. Also, the waveguide was moved closer to the woofer than in the original Pi4 baffle cutout plans. Reading suggests that close is a good thing- but for the current project it is a deviation from the original Pi4 design.
3. Finally, after reading much discussion on flush mounting, a 15mm MDF 'over-baffle' layer was added. This brings the front edge of the waveguide forward (VC alignment issues?) and adds and extra 90mm to the length of the ports. No problem in removing 15mm from each port tube, if necessary.
Please note waveguide center to woofer centre distance.
Still too soon to decide whether the finished version is better (or not) than pre-assembly test versions with driver/guide just squatting on top of cabinet (which was exceptionally good).
Can definitely conclude though that the $20 Pyle PLXR2 sub crossover ( http://www.audioroundtable.com/Semiconductor/messages/359.html ) project is a very positive addition.
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