Problem with Sub1500

[coherent_guy]

Hi Folks, I'm a new poster but long time reader of this forum and long time fan of JBL, I thought I knew something about JBL until I got here, quite humbling. I am looking for some advice regarding the Sub1500 driver, I have two obtained from Parts Express. I replaced the stock drivers in JBL PSW-D115 subs (I have two) with these drivers, with some minor cabinet modifications. I realize that simply putting these drivers in these enclosure/amp systems will be a haphazard experiment, but after reading the threads on the sub1500's and seeing the many different enclosures being used, I thought it would be worth a try. It works well at lower volume levels, but a moderate signal with low bass content causes them to sound like they are bottoming out, reaching their excursion limits, not a low pitched thud but a higher pitched, sharp "whap whap" sound. The cones do not appear to be reaching their maximun excursion, but that is hard to tell by eye. This occurs at a medium volume level, certainly less than the stock drivers were capable of, which are of much lower quality than the '1500's. The cabs are approx. 20" x 20" x 22", 5/8" thick, with a 4.5-5" diameter port of 12" length, the plate amp rated at 300 watts. I use the preamp level inputs with the crossover set to 80Hz. I checked the 1500's for orange glue and unglued spiders, not the case. I tried blocking the port to make a sealed enclosure, no difference. Are the drivers unloading in a mismatched enclosure? Amp clipping from impedance or other mismatch? Amp inputs being overdriven by preamp outputs (from each channel to Y splitter cable to L and R inputs on subs, or single cable to Center input, no difference). I highly appreciate any thoughts on this, it is frustrating me greatly. Is there an optimal enclosure volume/type? Is this driver power hungry and difficult to drive? Thanks much.

[chad]

I suspect that either:

1) the spiders are coming unglued (there are threads on this forum about this problem)

2) the drivers are causing a mechanical vibration in the cabinet (my band had a similar problem with our pro audio subwoofers, we had to add additional screws to the cabinet bracing).

Good luck, hope you can cure and enjoy them :).

[grumpy]

tried a subsonic filter? (below 20Hz)

amp is not clipping? a plate amp rated at 300w (4 ohms?)
could easily run out of gas... especially ~40Hz, where you'll have
a large impedance peak (remember, your amp puts out voltage, not
watts... could clip as low as 30w in this application).

loose/broken stuff (as Chad indicated)?
loose stuff nearby?
poorly routed tinsel leads whacking rear of cone?
Don't count on being able to tell excursion levels by eye.

I've run a pair in -roughly- the same config (volume, tuning)
with no such issue. Should take full rated power down into
the mid-low 20's (at least when modeled).

-grumpy

[Mr. Widget]

It doesn't sound like you have defective woofers... Based on your ball park figures it seems that you are using ~4 cu ft enclosures that are tuned to around 27Hz... any signal that is below that frequency can easily overdrive your woofers as ported enclosures unload below the tuning frequency. You need to tune them to a lower frequency, say ~20Hz and use a hi-pass filter, or use them in sealed boxes. The simplest and quickest thing to try would be to plug your ports and see if you like them in sealed cabinets. They are fairly low output this way and I am guessing that you are driving them fairly hard to bottom them out even in their improperly tuned cabinets so sealed boxes may not work for you... it can't hurt to try though.

You can also lower the tuning of the cabs by using a single 4" diameter port that is 16" long... you will likely need an L-bow as the box is too small for such a long tube and a single 4" port will likely have audible port noise.


Widget

[coherent_guy]

... for your suggestions, some have entered my mind earlier, such as the cabinet vibrating, it has one brace but is not the most solid cabinet around. I've lined the inside with damping material... has that become loose? The driver/power issue is one that gets beyond my abilites except to swap amps and see what happens, I have a Crown CE1000 that I'll try. I wish I had the impedance curve and TS specs of the original driver for comparison, it's not a great or common JBL model, stamped frame and two or three inch VC. The internal leads smaking the cone is to simple... so it might be true! A high-pass filter is a surprise, but I see the point. I'll post my results if I ever have any, and surf the sub1500 posts. Thanks again.

[Mr. Widget]

The internal leads smaking the cone is to simple... so it might be true! Is it a frightening and dramatic popping noise or something that is mildly annoying? When I overdrive my Sub1500s it is pretty dramatic. This occurs at high SPLs at very low frequencies. I did have one defective Sub1500 early on and it sounded like a typical VC rub... a mild grating sound. I would expect internal wires touching the cone to provide more of a buzzing sound.


Widget

[grumpy]

Had to adjust one of the leads on a SUB1500... and yes, it was more of a "huh?... it
shouldn't be making that sound" level of buzz rather than a wet-your-pants, voice coil
meets magnet sort of thing. Hoping the high-pass route will help, as the initial post
did seem to describe voice coil bottoming-out. -grumpy

[coherent_guy]

... the amp clipping, first suggested by Grumpy, I believe. I came to this conclusion after connecting one sub1500 in a PSW-D115 enclosure, directly to a Crown CE 1000 amp set to bridged mode, rated at 900 watts/8ohms, 1200 watts/4ohms. The input signal was a test CD with 50Hz, 40Hz, 32Hz, 25Hz, and 20Hz test tones. I was able to drive the sub1500 to the point where there was wind noise from the port, (which is flared inside and out!) which equated to high volume levels, with not one instance of the any distress from the driver at any frequency. I repeated this test with the enclosure sealed as well as I could manage, blocking the port, with identical results, the terrible sounds I heard that started all this never appeared. But this experience has brought new questions to mind, one being, what in the world do you folks that own these woofers drive them with? 1000 watt amps with 1/2 volt input sensitivities? These drivers are very insensitive, or technically speaking, power hawgs!! Connecting the Crown amp driven sub1500 to the rest of my system produced a whimper... where's the bass? I have the level control on the Crown wide open and set to its high gain mode, bridged, and the output level is no where near what the 'D115's plate amp could produce. I am using Revel Performa M20's as satellites, 6.5" 2-ways, at about 85db/1 watt spl at best, which should not be causing matching problems. I do realize that the plate amp likely has some EQ going on that helps things, and BTW, I have new found respect for that plate amp, in spite of the bad reputation of the PSW series. Until it seems to peter out, it produces tight, clean, and deep bass. I'm not talking about booming, sloppy bass, I'm using Krell preamp and amps, I love the "room lock" I was getting, the hall ambience that is more shuddering than air, the bass that is felt and not heard, I know what tight bass is, and I had it. For now, I'm going back to the plate amps(!), backing off on their level a bit, scratching my head, and trying to figure how to drive these things with another amp. Again, what in the world do you use to drive these things? I read in this forum about all the huge JBL floor standing monitors out there, all very sensitive with high spl capabilities, how do your sub1500's keep up? I just don't get it!! I used a second preamp for additional gain into the Crown amp, and it's still not enough. The crossover in that plate amp must really put out some voltage, I never had the 'D115's level control set wide open with the plate amp, always between 1/2 to 3/4, FWIW. What am I doing wrong :banghead:
Thanks everyone...

[Steve Gonzales]

If you want to stick with a plate amp, I suggest a 1000watt from Parts Express. It has some pretty cool feature like a parametric EQ. Here is a link.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-808

[reconed]

I'm using a Buttkicker BKA-1000 4A to power my Sub1500 in a 1.8 cu ft sealed box. This is a very low cost (~$250 on Ebay) Class D amp designed for low frequency transducers mounted to the floor or to furniture, but it works great for a subwoofer, too. It puts out 1100 W rms into 4 ohms, or 2100 W rms into 2 ohms. I plan to use it to power 2 Sub1500s in paralell as soon I get my second enclosure finished. I also am using an analog parametric EQ to boost the bass at ~22 Hz by 6 dB. I am running the amp's volume at the 12 o'clock position (half volume?) to allow headroom for the boost, and it is plenty loud for movies as well as music - in fact, I keep the volume down at least -6 dB on my receiver except when I want to crank it.

[johnaec]

I use one channel of a Crest CA-9, (900 rms/ch at 4 ohms), to power my Sub1500 for live bass guitar. Haven't run out of suds so far...

John

[coherent_guy]

Thanks for the suggestions gentlemen. Steve, I have been eyeing that PE amp for some time, it's not a clean swap fit with the existing amp, but not out of the running. Reconed, sounds like that Buttkicker was used with those so-called tactile transducers? No matter as you say, and the price is amazing, does that have a crossover in it, any EQ built in and what kind of inputs? I am amazed, Johnaec, that you use that driver for MI applications, but the proof is in the punch, right? Usually, aren't MI speakers very sensitive, like... oh... JBL's?!?! What kind of enclosure do you use, not sealed is it? Aren't MI bass enclosures almost wide open? Your experience tells me that I ain't overdriving that driver!
I'm trying an active crossover into my Crown after the preamp to see if I can get some more level out of it. Has anyone heard the Project Array 1500 sub, with the similar W1500 driver? JBL specs a 1000 watt amp in it, say no more! Before the D115 amps peters out, I'm telling you they sound incredible, I love these drivers, I'd love to hear a TiK sub, anyone out there hear/have one? Thanks again folks, I'll keep you posted.

[mech986]

... the amp clipping, first suggested by Grumpy, I believe. I came to this conclusion after connecting one sub1500 in a PSW-D115 enclosure, directly to a Crown CE 1000 amp set to bridged mode, rated at 900 watts/8ohms, 1200 watts/4ohms. The input signal was a test CD with 50Hz, 40Hz, 32Hz, 25Hz, and 20Hz test tones. I was able to drive the sub1500 to the point where there was wind noise from the port, (which is flared inside and out!) which equated to high volume levels, with not one instance of the any distress from the driver at any frequency. I repeated this test with the enclosure sealed as well as I could manage, blocking the port, with identical results, the terrible sounds I heard that started all this never appeared. But this experience has brought new questions to mind, one being, what in the world do you folks that own these woofers drive them with? 1000 watt amps with 1/2 volt input sensitivities? These drivers are very insensitive, or technically speaking, power hawgs!! Connecting the Crown amp driven sub1500 to the rest of my system produced a whimper... where's the bass? I have the level control on the Crown wide open and set to its high gain mode, bridged, and the output level is no where near what the 'D115's plate amp could produce. snip... I used a second preamp for additional gain into the Crown amp, and it's still not enough. The crossover in that plate amp must really put out some voltage, I never had the 'D115's level control set wide open with the plate amp, always between 1/2 to 3/4, FWIW. What am I doing wrong :banghead:
Thanks everyone...

Your setup sounds like it should definitely put out plenty of power. I'm wondering if something is miswired or set incorrectly? My thoughts bolded below:

I'm sure you have it but here's a link to the CE1000 manual at Crown's site:
http://www.crownaudio.com/pdf/legacy/125645.pdf

As you said, you should have the sensitivity switch on the back panel set to 1.4V (see figure 2.12) that would give the amp the most power for a 1.4V input.

Taken from the manual:
2.6.3 Bridge-Mono Mode
Make sure the amplifier is turned off and the level controls are turned down before you wire the system.

Typical input and output wiring is shown in Figure 2.11.

INPUTS: Connect input wiring to CH 1. (only)
OUTPUTS: Connect the speaker across the positive (+) output terminals. Do not use the negative (–) terminals when the amplifier is being operated in Bridge-Mono mode. Refer to Section 2.5 for output connector pin assignments. Make sure the Mode switch is set to the “Bridge” position when operating in Bridge-Mono mode.


NOTE: Turn down (full CCW) the Channel 2 level control when operating the channel pair in Bridge-Mono mode, as the Channel 1 level control works both channels.



Figure 2.11 shows a single sub hooked up to the left speakon for bridged-mono. I think you should follow the direction, if you hadn't already, to hook the speaker cable directly up to the two (+) outputs on the binding posts. The back of the amp pictorial shows language that says "For Bridged Mono, use ch.1 (+) for (+) and ch.2 (+) for (-) only" I think the figure is at odds with the directions if you leave the speaker hooked up to the left channel speakon connection only. That may be why you are getting such a low output.




I would assume that you have no clipping or fault indicators lighting up on the front. All your input wiring is via 1/4" plug or the barrier wiring is good and not shorted. Lastly, you may want to reverse phase at the speaker just to see if it a phasing problem with the sub and the rest of the system. I don't recall if the SUB1500 driver is a positive or negative for forward cone motion but its an easy check.

Also, if you are summing using a y-cable out of your preamp, could there be a miswire there where the low freq signal is out of phase and cancelled before it gets to the amp?

Something else I found in the manual:
4.1.5 Compression
A full-time compressor is in-line with the signal, reducing the risk of damage to your speakers. I wonder if by trying to feed maximum signal into your amp, its triggering the compressor to limit the signal?

4.3.4 Optional 0.775 V Input - Sensitivity Setting
The CE Series amplifier also provides an optional 0.775 V input sensitivity setting. If you determine that your application requires this sensitivity setting, please contact Crown Technical Support for more information.


That's all I could think of. Hope this helps.
Regards,

Bart

[johnaec]

I am amazed, Johnaec, that you use that driver for MI applications, but the proof is in the punch, right? Usually, aren't MI speakers very sensitive, like... oh... JBL's?!?! What kind of enclosure do you use, not sealed is it? Aren't MI bass enclosures almost wide open? Your experience tells me that I ain't overdriving that driver!Most MI speakers are fairly sensitive, mainly because most MI amps are relatively low power. I'm using 900 watts specifically because of the low sensitivity of the Sub1500. And the nights it gets used, it goes for pretty much 3-4 hours straight, (with short hourly breaks), so I can definitely attest to its reliability.

Right now, it's in an unmodified JBL 4628B cabinet, in place of the E145. That cabinet has a huge port, and I believe the tuning is around 30hz. Mids are handled by the 2118H, while the HF 2404H-1 is basically unused. I do have a design I'm going to build that will be using the E-110 for mids.

John (from remote, on vacation...)

[coherent_guy]

Again, thanks for your time gentlemen. Mech986, you sure put some effort into your post, even if it was cut and paste ;) Yes, there is much to get correct, or is that wrong, when setting that Crown correctly. The gain setting confused me the most, even after reading the manual, and I found little difference between the settings. I do think I had everything set as you spelled out, all in one page, a great cheat sheet! I think I found my problem though, more later. I had an odd thing happen, using one input on XLR to channel one only, configured as you described, with channel two's level set to off, at high input levels the clip indicator for channel TWO would blink! That was with an active crossover in the mix, a (cough) Behringer CX3400, which seems to have solved my input level problem. Back to your suggestions Bart, I have used both the Speakon and both + binding post outputs, although I will say I once had it set to bridged and connected to the Ch 1 + and - and it still played. BTW, in my CE1000 manual, it is Figure 2-10 (page 9) that shows the Bridge-Mono Mode connection with speakons, and the picture shows the sub connected to speakon output 1. There is an extra page supplied with the amp that instructs you to connect the wires to the Ch 1 and Ch 2 + connection points in the speakon connector for bridged mono use. It works, but is dangerous, isn't it, I have mine labeled to warn me. Anyway, I've been using the binding posts only lately, for easy phase switching. One problem I have now is the Behringer X-over only has balanced inputs on XLRs and I have only one XLR preamp output in my system, used on the main speakers amp. I was able to drive the Crown with a single ended RCA to 1/4" adaptor input jack, which likely explains my gain problem, running singled ended into balanced, I must confess :blink: . What did I loose gain-wise 3 or 6 db? I can't find this in the Crown manual. I did not notice that 0.775 V gain setting option, I hope it's easy to set, that may come in handy, thanks.
Johnaec, very interesting, so much for pro/MI and home speakers not mixing. I just don't understand why JBL abandon this driver. I guess they didn't with the new... W1500 is it? The original woofer in the D115 is a stamped frame, small voice coil unit, that JBL wants $450 in their replacement parts guide! More than I paid for the sub1500, as we know.
Any thoughts on driving balanced inputs with single ended sources?? Thanks.

[johnaec]

Any thoughts on driving balanced inputs with single ended sources?? Thanks.I mix and match balanced with unbalanced all over the place with adapters and no problems at all. Maybe I've just been lucky...

John