Sub 1500 in 4625 Cabarets

I found a pair of 4625 cabs on eBay and loaded them with Sub 1500's. The results are surprisingly good, since I don't believe the tuning is optimal. Perhaps you guys will run the numbers for me?

Allegedly, the boxes are 4 cu.ft. The interior dimensions calculate to 4.3 cu.ft., but deducting for the bracing, ports, and speaker volume, 4.0 net seems about right, at least for the E-140's that came in these. Sub 1500 is a little bigger, it would appear.

The ports, a pair in each, are 4" X 5-1/4" deep from the face. Somewhere in the literature, I believe I saw the factory tuning was to 40 Hz. I was going to plug the ports, but I'm not so sure now.

In any case, the bass is tight, low, clean, and effortless. I'm running them on a Mackie M-1400i, with the sub filter set at 63 Hz. If I crank the full 300 W into each that amp will deliver, it's clear the cabinets aren't made of thick enough material, but that's WAY more bass than I need here.

I ran them overnight with the local "boosted bass" FM station playing to break them in. Big difference when I got up this morning. These babies throb oh so nicely now. :D

Why would You cut them at 63Hz????

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Why would You cut them at 63Hz????

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It's low PASS at 63 Hz.

The mains are 4412's right now, running without any high pass, so I just need sub.

Similarly, these will ultimately mate with other Cabarets having 15" woofers.

The other option on the Mackie is 125 Hz. I can switch frequencies easily on the rear panel. When I do that, I perceive directional content from the subs.

There's also a low cut filter on there. I trust I have it "Off." Gonna go check that now. [Might be good if I cleaned them grilles, too....] :p

JBL Cabaret literature calls these "4.5 cu.ft." boxes, so I went back and carefully measured the interior dimensions: 28" X 18" X 14-7/8" = 4.3385 cu.ft., less the port volume of 0.0654 cu.ft. = 4.2731 cu.ft. net.

It's 1 X bracing, so the 1" fiberglass insulation everywhere says ignore it.

While measuring, I found and removed a 5/16" flat washer floating in there. (Wondered what the rattle was....) ;)

So, what have I got transfer characteristic wise, and how can I "optimize" them? What happens if I plug the ports?

Test disk: "A Momentary Lapse of Reason"

Mackie actually delivers 425 W into 4 ohms, each channel....


Footnote: I once asked JBL Pro customer service about puting 2226H's in these boxes in lieu of the E140's that are standard, and if any change in tuning would be recommended. "No good. Totally different drivers requiring different boxes and tuning altogether," was the initial response.

When I pointed out that the 2226H data sheet response curve was spec'd using a 5.0 cu.ft. box tuned to 40 Hz, and that the SR Series equivalent that superceded Cabaret using 2226H was essentially the same volume and tuning, it became, "Should work, then. How come you're asking ME?" :confused:

Well, this is turning into a monolog, albeit instructive:

WinISD says these 4.0 cu.ft. cabs are presently tuned to 42.5 - 45 Hz. I am clueless as to why they sound so good. Apparently, the Sub1500's are "forgiving" in application, i.e., you can put them in just about anything.

It also says I "want" to tune them to about 27 Hz, which will require extending the ports to 20", achievable using elbows. Yup. Maybe use them clamp-on rubber elbows to test rather than ripping out the existing cardboard tubes. Group delay peaks at 22 ms. Not TERRIBLY terrible....

Plugging the ports gives essentially linear rolloff down from about 50 Hz. Seems this would require EQ to work well. I just don't get in my own analysis why others here suggest a 4.0 cu.ft. closed box is a viable option for Sub1500.

Part of the problem may be that we don't have firm T/S numbers, at least, not posted here. It's difficult to design using floating Vas and Fs. :mad:

BUT, it seems I can't go VERY wrong extending the port lengths to lower the box tuning. So, off to Home Depot and the plumbing supply store....

:rockon1:


Sidebar: I also don't understand why Cabaret gets so little play in this forum. There's few systems sweeter than 4628B with E145, 2118, and 2404, at least to the ears of those who prefer cone to horn midrange. A bunch of these have been appearing on eBay recently. Would only they were mirror-imaged....

And 4612B, with dual 2118's and 2404. Perfect rear/side boxes, no, aesthetics notwithstanding? [This from a 4425/30/35 B380/460 fan, LOL....]

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Well, this is turning into a monolog, albeit instructive

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Hey, I am enjoying it! I'll have to find something to house the two I bought at some point when I have finished my four 2235's project.

Please, keep us posted as you go:cheers:

Chas: Heh, heh. Maybe you'll help with my NEXT project, then, which is four LE 14A's in a triple-chamber bandpass box modeled on Control Sub5. :D

Just gotta refoam these last two, and start another thread, LOL....

Bought a fifth one as a spare on eBay, but the jerk seems to be stiffing me on shipment, going on two months now. :mad:

Giskard: Well, plugging the ports certainly WOULD be easier. I'll try that first.

Mackie Low Pass Filter - Switched: 63Hz/125Hz, 3rd Order Bessel

Alternatively, I have BX63A, which is 12 dB, if I recall, but with boost, and adjustable from 63 to 125 Hz....

Which is preferable with the closed box?




Bo: Yup, I used a combination of those and PE Clio numbers in WinISD, compromising on those that don't agree. There was some discussion of those being from one sample only, and PE numbers being from "not broken in" unit. Hard to nail down without the published specs, which must exist somewhere....


Alas, Giskard's very informative posts seem to have disappeared. He's a phantom poster in this thread, apparently. Heh, heh....

Giskard: Kindly repost, if you would, good sir....

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Originally posted by Zilch
There's few systems sweeter than 4628B with E145, 2118, and 2404, at least to the ears of those who prefer cone to horn midrange. [This from a 4425/30/35 B380/460 fan, LOL....][/I]

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Yeah, I think this system has potential, but not for hi fi (at least to my taste). If I am reading the crossover correctly, the E145 and the 2118 both run full, so I would expect a distinct midrange emphasis in the sound.

I think Giskard's comments about boxing the sub1500 should always be understood in the context of taking into account the effects of room rise in the VLF. It would be a matter of individual taste for how you want or need the subwoofer and the room to work together.

David

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Originally posted by speakerdave
Yeah, I think this system has potential, but not for hi fi (at least to my taste). If I am reading the crossover correctly, the E145 and the 2118 both run full, so I would expect a distinct midrange emphasis in the sound.

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Hmmmmm. I've never opened up the pair I have to see the crossover, or looked at the schematic, but they do sound good here. It's them I intend to mate with the Sub1500 Cabarets. If the woof and mid are running direct, it sounds like some effort in building or installing a suitable crossover would be worthwhile.

Seemingly, it's a killer combination of drivers in a right size box, as above, worthy of an appropriate "tweak" for home hifi or media room use. One 5-7/8" dia. port, 5-1/2" deep. Alas, multi-driver system response analysis is WAY beyond my expertise here....

YEEOOW, Dusty in there! Need to "exercise" them more. :D

I wasn't aware when you posted that you had the speaker. Personally, I wouldn't touch if I liked it the way it is. You're listening to it and I'm just looking at spec sheets, so already you know a lot more about it than I do. I was just interested because I've been thinking about that combination. That mid/tweeter combination was briefly discussed on another thread recently, and it may be that JBL's handling of it in the 4628 and the 4612 (mid run full and a nominal crossover frequency of 3k) is the only way to get them to work together. Gordon pointed out that when he ran the numbers on the crossover component values the true crossover was more like 4.5k. The problem is that the tweeter doesn't really go down to 3k and an 8," even at that frequency is beaming. The two sources paralleled in the overlap region may help with dispersion, I don't know. The result might be that even though on-axis response may have it's peculiarities, the balance in the wider field may be good. Besides, mid-frequency emphasis is more or less standard procedure for sound reinforcement, isn't it?

You might be interested to know that Gold Sound (you can find them on the web) used that mid/tweeter combination in their GS 11 kit, but I have not seen their crossover.

David

Here's the URL for that GS 11 kit.

http://www.goldsound.net/kit11.htm

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Originally posted by speakerdave
Besides, mid-frequency emphasis is more or less standard procedure for sound reinforcement, isn't it?

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"4628B Keyboard/Reinforcement - Specially designed for organ, piano, and synthesizer, with a superb bottom end for clean pedal tones, the 4628B is characterized by extremely low distortion and a wide frequency range"

JBL Pro's home turf is sound reinforcement, which particularly emphasizes clarity in the vocal range, with high SPL, low distortion. I'm not sure that translates to mid-frequency emphasis, per se, though.

Clearly, the current driver and system offerings reflect this; we don't see many standard full-range systems that port well to home use. Few audiophiles are building around the flagship 2226H 15" as their system woofer, I wouldn't imagine, respectable as it may be.

Assuming the design objectives of the 4628B stated above were realized, it's anomalous in this respect. If you wanted to cut through the band with vocals, you used the compression driver version, 4691B, the most popular. Successors to Cabaret refined and expanded upon that success in both portable and installed systems, as I see the evolution, at least....

We really need to see the 4628B system curves to know the actual outcome.

Well, I've drifted somewhat off-topic here, but Cabarets often show up on eBay at reasonable prices, and I think they're worth considering, even if only as convenient test boxes. Perhaps more here will give them a second look. The 4.5 cu. ft. units ship economically via UPS or FedEx ground.

I'll go plug my ports now.... :p

Well I don't know about 2226's but an E-145 is a great HiFi woofer. You won't get too much below 40hz and you definately need a sub but what you do get is great. Fast lean and clean. Great definition on notes and very good effciency at 98db. The 2118 can be a great midrange driver and the 2404 can also excel. All you have to do is limit there range a bit. Your right the 4628 box is not set-up the way many would like but the driver set is damn good. All it takes is a little imagination and you could make a killer speaker with that line up.

Rob:)

"Giskard: Kindly repost"

I can't remember what I posted.

"Plugging the ports gives essentially linear rolloff down from about 50 Hz."

Good! Exploit that.

"Seems this would require EQ to work well."

and/or proper bandwidth limiting along with proper room placement. They're going to exploit the natural roll-off of the transducer/enclosure and the natural rise of the listening room.

"I just don't get in my own analysis why others here suggest a 4.0 cu.ft. closed box is a viable option for Sub1500."

Because it is viable and we've been doing this subwoofer/ultrabass crap since the B212 first rolled off the line way back in 1977. Subwoofers are bandwidth limited devices by design. It is fairly pointless to evaluate subwoofers without various filters included. WinISD can't do that for you. Nor can it show the mechanical limitations of the transducer. What might look good in WinISD might mechanically fail under actual use.

The 1500SUB was designed for sealed enclosures. Everything about it is designed to withstand the pressures of operating in an airtight sealed enclosure. It is nice that it is versatile enough to also be used in vented enclosures with excellent results.

If someone posts that they are running 1500SUB drivers in 5 cubic foot vented enclosures or 1.5 cubic foot sealed enclosures and that the drivers are doing everything they could have hoped for, I take them at their word. If they post that the drivers aren't living up to all the hype then I know it's "user error". If they post that they prefer vented to sealed then I can understand that. If they post that they prefer sealed to vented than I can understand that as well.

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Originally posted by Zilch
Alternatively, I have BX63A, which is 12 dB, if I recall, but with boost, and adjustable from 63 to 125 Hz....

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I'm not sure how well the BX63 would work in this instance. I'd have to evaluate a vented enclosure volume with a 1500SUB that would work with the static EQ boost at ~ 26 Hz. Frankly, I see no reason to use assisted vented alignments with this particular transducer. If one went sealed, the BX63 might offer a bit too much boost unless the volume was really small so response was sufficiently down at 26 Hz to take proper advantage of the boost. Try it and see what happens.