JBL 2405 for Jamborees

[Srinath]

I have a Jamboree set that is a little work in progress.

I have been holding onto 2 JBL 2402's that were modded to be 2405's for use in the horn section to be mated to the jamborees.

Am I on the right track ? Is the 2405 a good one to mate to a 402 or similar horn and mate it to the jamboree.

[capo72]

What midrange driver do you plan to use? If you plan to use a JBL 2405 tweeter, then I'm assuming this is a 3-way project.

[Chris A]

17 hours ago, Srinath said:

Am I on the right track?

If you're talking about a three-way using the Jamboree bass bins (good to ~500 Hz) and the JBL 2505 tweeters (good from ~5-20 kHz), the problem really is "what is going to provide the SPL between 500-5000 Hz?".

 

If it were me, I'd use a dual-diaphragm 2" compression driver to go from ~500 Hz --> 20 kHz and find a good horn to cover that range (a K-510 would just barely do it) and sell off the 2505s.  The BMS 4592ND drivers will cover that band easily, or more if you can find a horn with a larger mouth size.  The cost of two BMS 4592NDs is about $1100.

 

You could also try a winged/stacked set of ESS AMT-1s for a much lower price (about $650), and sell off the 2505s to foot most of the bill for the AMT-1s, the wood for the wings, and a DSP crossover (such as a miniDSP 2x4 HD).  That would be a pretty good approach. 

 

Any way you go, you'll need a calibrated microphone (e.g., UMIK-1, $95) and USB cable to your computer running REW (freeware) to dial everything in using a DSP crossover.

 

17 hours ago, Srinath said:

Is the 2405 a good one to mate to a 402 or similar horn and mate it to the jamboree.

The K-402s and K-691 drivers would work really well (i.e., a KPT-402-HF assembly -- which you can buy from someone like Cory at Paducah).  You could mount the 2505s on top, but you'll need two miniDSP 2x4 HDs (or one miniDSP 4x10 HD for everything).  Note that you'll need 6 channels of amplification to use the Jamboree bass bins, K-691 midranges, and JBL 2505 tweeters.

 

Chris

[Srinath]

I was hoping to do 2 way but if 2 way well then I guess its 3 way. The 2402 (modded to be 2405)'s are good 2400 hz and up. But Jamboree bins with eminence Omega's aren't good to 2500 like some of those 15 EV/Altec's were ?

I will have to think it over a bit more, I can do a grill vane face on the 2402 like someone on AK has developed, and use a soft dome mid that works 700 to 5K - but again for 3 way I have better options than the 2402 I guess.

I have ESS amt 1b's sitting around too BTW. But they're promised to someone else in case he does some other stuff.

[PrestonTom]

I can't imagine 15 inch woofer being good up to above 2kHz. That is asking quite a bit from a woofer. If it does make sound, it may not be very good sound (harmonic distortion but IMD would be the big worry). IIRC, the Jamboree is a folded horn design. Those typically cut off the highs due to the folding geometry (whether or not the woofer puts out much energy). So swapping woofers will probably not help and besides the back volume and throat were designed for a specific woofer specification. 

 

More optimistically, if you were able to extend the bandwidth from the bass bin to get an extra octave (or two octaves is better re: 500 Hz), then the Klipsch K-510 (as mentioned above) would then become a great option for a two-way design. The horn would (or should) be small enough to fit inside the cabinet (you would need to check this). The K-510 measures 9x15.

 

Good luck,

-Tom

 

I just remembered that the Jamboree is a bi-furcated mouth. That design, similar to the Jubilee, can cause some problems when you cross too high. The problem is the polar dispersion (output as a function of angle) can drop off as you go to the side (as normal) but they can pop backup again ("petals" if you looked at the polar map). I have no idea whether anyone has measured the Jamboree. I know for the Jubilee, this can be a headache if you were to cross at higher than 700-800 Hz. I can't comment specifically on the Jamboree.

[Srinath]

IIRC the Jubilee was a 2 way. Or am I mistaken ? Maybe the jamboree is not. Let me look.

[capo72]

Move on from the JBL tweeter and use Chris A's advice. I think you will be disappointed in the JBL tweeter response on the low end. They are fantastic from 5 kHz and up, but thinking you are going to get good response @ 2.4 kHz is wishful.

[Srinath]

Yea I'm pretty OK with taking the 5K and up for 2405. I have excellent mids that do 700 - 7K.

The worry is the 500 to 700 if my bass bins can go to 700 or I need different mids.