What to build??? 4560 vs 4320

[retro soulman]

im thinking of build a new pair of cabinets to replace my 4530! My 4530 are loaded now with Gauss 4580 (paper dust cap), 2390 lenses - 2445 driver and 2405 tweeter. The system is active using a BSS 2 way crossover (passive for the tweeters). Lows are driven by a crown psa2 and mid highs from a tube sound valves vta 70.
So here are some questions:
i really like the look of the 4320 in utility grey, i can find a pair of 2420 with burned diaphragms but i got also a pair of early 2425 with aluminum 2420 diaphragms so i can replace the bad ones of the 2420 drivers. Also i can find a pair of 2307 throats and i can buy from ebay a pair of lenses. I got also a pair of alnico 2402. For lows i could use the gauss drivers but i also got 2 pairs of k140 for now. Does it sound like a correct project? I can also find a 5234 crossover with 800hz cards ( i got a 5232 with 1200hz cards), btw how good or bad is the sound of these old crossovers? Can it be compared to my bss 310?
My second option is the JBL 4560. I will use the drivers that i got now and im waiting also a pair of 2220.... I love the warm mids from these cabinets but they are so big! Also the time alignment of the drivers is a big plus on these. Also they are much harder to build than the simple 4320...
if someone got plans from 4320 will be a huge help for me! Can find them online...
Best regards, Nick!

[Lee in Montreal]

Oh well. It all depends on what you expect from your cabs.

The 4560s are good for reinforcing vocals. Not much bass though.



The 4320 is just another bass reflex cab.

[retro soulman]

Oh well. It all depends on what you expect from your cabs.

The 4560s are good for reinforcing vocals. Not much bass though.



The 4320 is just another bass reflex cab.

The truth is that i love horns and all my cabinets until now where horn loading enclosures, but i would like to hear and something different also. What about these old crossovers?

[Lee in Montreal]

Well, if you like bass horns, then I suggest you look into newer design horns such as the Rog Mogale's Super Scooper using an 18" woofer. Could probably use an 18" 2240h in there.



Compare response with 4520. Way better bottom end on the Super Scooper.

[retro soulman]

Well, if you like bass horns, then I suggest you look into newer design horns such as the Rog Mogale's Super Scooper using an 18" woofer. Could probably use an 18" 2240h in there.



Compare response with 4520. Way better bottom end on the Super Scooper.

I don't care much about back loading horns, i was also a 4520 owner using k140 woofers, nice smooth bottom. But i prefer front loading horns

[RMC]

Hi Nick,

You like the grey look of the 4320, but you love the warm mids of front loaded horns like the 4560. These are as opposites as you can get... The first from the Studio Monitor Series with well behaved response and everything, and the second from the Sound Reinforcement Series with high output and not so well behaved response and manners... I know, they say that opposites attract. Maybe, but not particularly in this case...

"Does it sound like a correct project? " No, not at all, for the 4320, with the woofers you have on-hand nor for the up-coming 2220. All of these (4580, K140 and 2220) would be more suitable for a 4560 project than a 4320 project. JBL used the 2215 in the 4320 Studio Monitor for good reasons. Let's look at just a few T/S parameters of the above drivers (the very basic ones needed to design a bass-reflex box, I've added Xmax figures for another reason see further), as this should convince you there's little hope for an APPROPRIATE 4320 :

Gauss 4580: Fs 31hz, Qts 0.23, Vas 7.0 cu ft (198.1 Liters), Xmax 0.090 in. (2.286 mm), numbers from High Efficiency Speaker Asylum web site
JBL K140: Fs 30hz, Qts 0.21, Vas 297.3 Liters, Xmax 5.08 mm, taken from JBL T/S parameter Tables
JBL 2220A/H: Fs 37Hz, Qts 0.18 (H 0.17), Vas 297.3 Liters, Xmax 2.03 mm (H 3 mm), JBL's T/S Tables/Data sheet
JBL 2215A/H: Fs 20hz, Qts 0.21, Vas 736.2 Liters, Xmax 4.06 mm, from JBL T/S parameter Tables

Naturally, all the above numbers are valid providing your Alnico magnets are OK and drivers are original or have been reconed with original Kits, if not you're on your own for these T/S numbers...

Comparing woofers on-hand (up-coming) with the proper woofer for a 4320 (i.e. 2215), you can see the Gauss is "short" on low Fs but way off on Vas, same applies for the K140, the 2220 is pretty far on Fs, somewhat away on Qts and still far away on Vas... Also, for matching puposes with a compression driver/horn, keep in mind these woofers all have a different (higher or lower) sensitivity rating.

You may still decide to build something that physically LOOKS like a 4320, but don't necessarily expect the same cabinet/vent dimensions and low frequency performance as a real 4320 with the woofers you have in mind... The only way to know what you'll end-up with, is to run a number of scenarios in Speaker Design Software with the T/S data for your drivers in order to design an appropriate box.

Cabinet drawings or plans could be calculated from "reverse engineering" of 4320 spec sheet dimensions given, but more difficult for ducted port (vent tuning) since no info given.

Making yourself a Grey 4560 would probably match your tastes for cabinet colour along with the warm mids of the front loaded horn. I guess this would be about as good as you could get. Yes, still difficult to build, and to find GOOD drawings/plans faithful to the original. Plus, remember these are long throw cabinets usually for large halls and outdoors environments according to JBL. The 4560A's vented rear reflex chamber, with stated usable response to 45hz, provides a small improvement in the bass range, still not at the same level as the front loaded wave...

JBL Professionnal Series Low frequency enclosures 05/1980 has a paragraph on front loaded horns used with 2205, E140, E145. JBL warns about drivers with longer cone excursion (than 2220), cone may hit horn throat in front loaded horns if too high power input at very low frequencies (same applies to K 140 re Xmax).

Since the suitable drivers and 4560 cabinet are designed for maximum output SPL (high efficiency), not for maximum Fidelity, personnaly, because I don't like mid-bassy sound, I would apply an EQ cut of about 4-6 db on mid-bass frequencies (approx. 100-1000hz) for more natural sound as may be needed, specially if compared to a 4320's much more uniform response.

Highest recommended crossover frequency for Gauss 800hz, for 2220H 1,200hz. My K and E series documents don't specify that number for the K/E 140 but I would imagine the same range of 800-1200hz. BSS/JBL electronic crossovers I don't use so I cannot comment on them, I use Rane AC22 electronic X-overs. Regards,

Richard