help with JBL 2360A project

[charly chile]

Yes, perhaps not having the sound of the reversed polarity rear midrange open baffle U-frame's output bouncing off the back wall and combining in an interference pattern requiring drastic EQ to be reasonably flat in the listening area may be preferable 😉.

Yep, that s what theory says, specially my case where I am not able to put baffles far away from the back wall.

Will be sort of inexpensive experiment, I should report back in a week more or less with empirical and qualitative results 🙂

 

[NBPK402]

Any reason to not use the EV DH1a drivers with the 2360A horns? I use them crossed over at 500Hz, and they sound great IMO.

 

[nhuwar]

If I were you I'd try and find a pair of jbl drivers with 4" voice coils. But I've also heard good things about the dh1a too. I'd use jbl 2446's if it were me. With aluminum Diaphragms of course.


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[SoundRight]

Yet to try/measure FR with my JBL 2360a's with EV DH1a's, but have used DAT's to test the drivers (consecutive serial nos!) and create impedance plots with horns attached which has enabled me to create a passive EQ circuit which also levels the impedance to present an easy load and maximise amplifier damping from Fs to 20KHz. (Yet to have the boards created for this project!)

I did the same though for my current system which is based on the P Audio 4525 (the 90 x 40 with the slot/circular throat..same as the Goldwood pb450..same horn!) with excellent results. I have found using science and getting the basics right bring rewards and rather more so than swapping cd drivers/horns etc or repeating the usual arguement about CD vs Tractrix vs spherical or whatever...so here are some plots (P Audio 4525/Beyma 750Ti at 15,30,45deg Horizontal, Impedance plot showing the +/- .5ohm deviation and 0 deg phase angle.. and a decay plot to enjoy! Crossover is around 900Hz with a Rane 23s active, delay was optimised using an analyser, to provide a flat response and minimum phase condition with the 10" mid. Vertical driver spacing as per Pi loudspeakers to provide nulls vertically at +/- 30 deg to suit the horns 40 deg vertical dispersion. The horn cut off is supposed to be around 450Hz so doubling this frequency ensures we are in the territory of full directional control..)

 

[grec]

Don't worry your not being difficult. No, the altec 515 would beat anything you put it up again in the midbass region. In my opinion. I forgot a out the omega pro. An 18 won't do as well when asked to produce higher frequencies. A 15 does much better do to moving mass. Plus there are more efficient woofers out there.. If you run a the workers on a separate amp of, I'd say 10 watts or a little more you would do ok with a 97 db woofer. But if you don't want to crank it up once in a while you can do with less Are they going into a small room or a large one?

Nick It will not. Altec 515 - beautiful tone, no kick. JBL will beat Altec easy below 600Hz. Take a look on JBL 2265HPL it got best from two - kick, tone and it's cheaper.

 

[SoundRight]

Not seeing anything but subjective here...a cone driver performs according to its Thiele Small parameters. No magic, no alchemy....18" cones and "moving mass"? No different to any other cone driver. It's all down to motor size and "power". We all know those with weaker magnets, resulting in high qts, are better matched to open baffle because of the matched air mass each side of the cone.

But I'll guarantee if you take any same size loudspeaker, and create designs with identical frequency response in either sealed or vented by varying cabinet volume and tuning...they will "sound" identical. Different cone sizes will have different dispersion capabilities of course, rule of thumb closing to around 90 degrees where the diameter is equivalent to around one wavelength....

True that stiffer cones will break up earlier but all such response anomolies should be dealt with and preferably avoided...?