Larry-n-Robben [mkII]

Just in case I come over as the most negative poster in Z/G, I thought I had better come up with a more positive game plan.
After showing SWMBO a picture of a JBL 4311 [a speaker I am am not very enamoured with - except for the horizontal box layout] I think I have the go-ahead for the replacements for my Morduant Short 817's.

People at Rory's bake off will have seen the cabs which I am using. These are fairly hummungous [though not quite Merlin's "disco in a shed" type of system] at about 100 litres outside dimensions.
Minus the mid-top box, wall thickness [18mm - with lots of bracing], and large slot reflex; I reckon they are about 60 to 70 litres internal for bass.
I am only using about 1/3 of the reflex slot [tuned at 25 - 28 Hz hopefully].
The remaining 2/3 slot will house the X-over. For bass I am using the Peerless XLS 10" drivers. These are optimised for use with an ABR. In my speaker they are used in a very oversize [overdamped] reflex enclosure.
In an overdamped box, the port output at 25-28Hz is dominant with a nice 2dB port peak below 30Hz..
Since the response is flat to below my music range [eg 33Hz = killer B - a 5 string bass], with minimal delay [because port tuning is below 30 Hz], I'm happy.

The bass driver will X-over at about 300Hz [2nd order] to the 4" bass-mid and treble drivers from a pair of JBL control 1's. Since these produce a high quality of mid/treble it would be stupid not to use them [at the £69 that Richer sounds used to sell them for, of course].
I have both the Control 1G [with a plastic tweeter] and the Control 1X [with a titanium tweeter] so I can try either tweeter.
Those who are troubled by theory might speculate if I should reverse my polarity, when using 2nd order filters to allow "integration at X-over"...
The correct answer to me is of course "Why??".
Since my bass driver is ~260mm and mid driver ~100mm, then the closest spacing is about 90mm and the furthest spacing about 450mm. Since 90°@300Hz = 283mm [ie less than the driver spread], how can the X-over be measured to within 90-180°??
In the Control 1[whatever] the bass driver is run "full range" with a compressor formed from a filament bulb to limit the bass. The treble crosses over at either 4 or 6KHz depending on whichever JBL leaflet you read... In my system I will keep the treble X-over values, but substitute better components.
I'll try to post as the speakers take shape. The total cost is coming in at about £350 so far. They should output from about 25Hz up to to whatever..The only downside is a sensitivity of about 85dB [but flattish to 25Hz] and an impedance nearer
4 ohms. I might need a bigger amp

cheers,

Graham C

 

pah nothing but a tiddler

 

You know, I've got the 2 cabs stacked in the bedroom. I reckon they look mighty fine.. I asked the boss if I should buy another pair [4 in total]..

Well, if she gives me any grief, I'll tell her mother what her reply was [and I wouldn't rumble with my mother-in-law...]