Where to mount the075/077?

[jblwolf]

I will be using le15a's,my sub will use 2-2245's,the rear channels will use le14a's or le15's(I'm using 5.5 cuft cabs),375's (1237-1290)also mounted on top of the cabinet and 075 or 077,I always liked the stock x-overs,this will be the first time I used the ac23's,first on the agenda is getting the front channels up and running, using the passive x-overs.

[Mr. Widget]

Thanks for the update Ian.

I have quite a bit of respect for Nelson Pass and his work. I am sure that what ever they put out will be technically excellent as well as actually good sounding and thoroughly listened to. So many designs are theoretically excellent and the designers believe in their theory more than their ears.

Scott, I have read your posts condemning 24dB slopes before. I am not sure if it is the slope or the design, but in the case of Rane I must agree I don't find Audio Nirvana in their crossovers. In my dedicated 2 channel setup I am using a 12dB Audioarts crossover. I like it's sound a heck of a lot more. When I first saw the ads for the new Pass Labs variable crossover, my first thought was GREAT- then I checked my checkbook. A Passdiy project would certainly be welcomed.

The problem with active crossovers is that they must be as good as your preamp or you will hear the signal degrade. Of course with passive crossovers there are all of the well known problems associated with them.

[Kevin McDonald]

I'm probably goiung to cut the baffle tomorrow (nice hard maple stock) and I don't wanna do it twice.

Same beaming issue as the 2405's? I had been planning to mount them slightly higher than ear level, above the mid horn.

[Mr. Widget]

I don't have personal experience with the 076s but on paper they are very similar to the 077/2405. I would bet they are the same.

As you probably have thought about, the further away your listening position the more off axis you can be. (In inches not degrees.)

[4313B]

The 077/2405 is spec'd at 140 x 40 at 10 kHz. The 076/2403 is spec'd at 90 x 60 at 10 kHz. The 075/2402 is spec'd at 40 conical at 10 kHz. The 075/2402 is "good" to about 15 kHz and the 076/2403 and 077/2405 are "good" to about 20 kHz.

The direct radiators, such as the 066, are spec'd at 140 conical at 8 kHz and falling roughly 80 degrees per octave above 8 kHz. The 066 is "good" to 21 kHz and the 044Ti/046Ti are "good" to 27 kHz. If I remember correctly, the 033 is "good" to about 16 kHz and the 044 is "good" to about 18 kHz.

The direct radiators are significantly flatter in their response than the ring radiators at the expense of extreme SPL, but they are lower in distortion content as well. EQ and careful baffle placement can compensate for some of the "peaks" and "dips" experienced with the ring radiators. (I personally prefer using the 2504 bracket and forgoing baffles altogether unless mounting flush on the back wall in built-in applications) The design of the ring radiators hasn't really changed since their inception (with good reason, they're tough to beat) whereas JBL has continually tried to improve their direct radiators (also with good reason ). The addition of the 2404 was quite nice in rounding out the ring radiator family.

[4313B]

"I will be using le15a's,my sub will use 2-2245's,the rear channels will use le14a's or le15's(I'm using 5.5 cuft cabs),375's (1237-1290)also mounted on top of the cabinet and 075 or 077,I always liked the stock x-overs,this will be the first time I used the ac23's,first on the agenda is getting the front channels up and running, using the passive x-overs."

You'll kill a pair of LE14A's in that large of an enclosure unless you tune them quite high or keep the power down, you might want to stick with the LE15A's instead. Are you using 075's because you have them or are you going to buy some? They'd be ok for surround I guess but I can't see using them for mains unless you have nothing else to use instead. If you're going to use 2245H subs I'd have to recommend looking at using the LE14A's/LE15A's in sealed enclosures to increase their transient response. Keep their Q in the 1/sqrt(2) to 1/sqrt(3) range.