Unpleasant noises from my IB

**toecheese** · **12-11-06, 11:57 PM**

My IB is a dual-15 Tempest setup, driven by an EP2500 (tuned by REW, of course).

The last two nights it is making some ugly noises. Of course, it is hard to describe, but I'd call it a 'muffled rattle'.

Suggestions on how to track it down and what to check?

Here are some pics of the back of the sub: http://farzanegan.org/ht/2006/07/tal...-backside.html

**Otto** · **12-12-06, 06:46 AM**

Hi toecheese,

If it were me, I'd probably try to recreate the problem with REW. See if it will happen with pink noise or tones or a sweep at a low volume. I would probably prefer tones, but a sweep will give you an idea of what tone might cause the problem, and pink noise will cast the widest net. Start turning it up (within reason, of course) until you hear it. If you can, good. Now try to figure out what's rattling!

Also, presuming that it could be a driver, you could disconnect one driver, and then the other, to see if the problem follows one.

Good luck!

**Darren** · **12-12-06, 08:58 AM**

Check the mounting screws, be sure the drivers are secure. Next check all the joints on the manifold to be sure none have separated, you might want someone to play some test tones while you are at the manifold and see if you can isolate the noise.

**toecheese** · **12-12-06, 03:48 PM**

I just got an email from the guru of IB (Thomas) and he suspects damaged voicecoils... time for some tests. :-((

**toecheese** · **12-12-06, 03:59 PM**

Well, one of the two has a rubbing sound when I push it in. Grrrr!

**toecheese** · **12-12-06, 04:01 PM**

Looks like they're doing the tempests again: http://www.acoustic-visions.com/~aco...mpest_classic/

Anything beat them price/performance-wise for an IB? I went to the link off the cult forum and there are 18" Canadian drivers for cheap... hmmm.

**WillyD** · **12-12-06, 04:13 PM**

Yes.

http://www.partsexpress.com/pe/showd...number=295-190

**toecheese** · **12-12-06, 04:17 PM**

Yeah, those are listed on the cult driver page: http://www3.sympatico.ca/bonaz/IB-Sub/IBdrv-01.htm

The xmax numbers don't match up to what's in the spreadsheet though...

**Darren** · **12-12-06, 04:45 PM**

You might consider doubling the drivers to 4 so you don't have the same issue again.

**toecheese** · **12-12-06, 05:25 PM**

Yes, if I don't get an exact replacement, I'll have to rebuild my manifold anyway- so I'd make it a 4-way.

**WillyD** · **12-12-06, 07:55 PM**

Quote:

toecheese wrote:

Yeah, those are listed on the cult driver page: http://www3.sympatico.ca/bonaz/IB-Sub/IBdrv-01.htm

The xmax numbers don't match up to what's in the spreadsheet though...

Thats cause they actually aren't on the the cult driver page, for whatever reason.

**Chrisbee** · **12-13-06, 06:22 AM**

What are the economics of driver voicecoil replacement if that is the problem?

**toecheese** · **12-13-06, 05:32 PM**

Not sure- yet. I'll see if they sell a rebuild kit.

**mrogowski** · **12-13-06, 07:48 PM**

Quote:

toecheese wrote:

Looks like they're doing the tempests again: http://www.acoustic-visions.com/~aco...mpest_classic/

Anything beat them price/performance-wise for an IB? I went to the link off the cult forum and there are 18" Canadian drivers for cheap... hmmm.

http://www.mach5audio.com/product_in...b928ce4f67e177

I assume you will want to replace them asap. I am currently working with a reseller in MD which will result in cheaper shipping costs for many. They won't be made available for at least a month tho...

Best,
Mark

**Exocer** · **12-13-06, 08:46 PM**

mr.ogowski, That is awesome news! the only thing holding me back from purchasing a driver were shippings costs...(yes all, I am THAT cheap).

toecheese thats strange, I was definitely going to consider tinsel slap as a possibility. If you're noticing something rubbing its probably not tinsel slap. Have you had a chance to try each driver free-air?

**Chrisbee** · **12-14-06, 02:43 AM**

Perhaps the Cult's advice on 2 x 15" as a start pack is just too optimistic?

4 x 15" or 4 x 18" offers a safety net for those dangerous moments in films when you watch them for the first time and don't know what to expect.

**Darren** · **12-14-06, 09:52 AM**

Quote:

Exocer wrote:

mr.ogowski, That is awesome news! the only thing holding me back from purchasing a driver were shippings costs...(yes all, I am THAT cheap).

toecheese thats strange, I was definitely going to consider tinsel slap as a possibility. If you're noticing something rubbing its probably not tinsel slap. Have you had a chance to try each driver free-air?

I don't think you can consider your decision cheap when the shipping doubles the cost of the driver

, it is good news that shipping charges will come in line with normal expectations. Too bad it costs so much from Canada.

**Ayreonaut** · **12-14-06, 10:20 AM**

I use the Mach5 MJ-18 drivers and they can dish out more than I can take. But keep in mind that the x-max on the MJ-18 is pretty low for an 18". For a fair comparison I say it's 4 x MJ-18 vs. 2 x Other 18" drivers. They're still a bargain if they give you enough output. Sounds like you might be pretty bass hungry though...

**Darren** · **12-14-06, 11:11 AM**

Actually 4 of those 18" drivers is equivilent to only two RL-P 15 15" drivers in displacement. A great bargain nonetheless for those who are budget minded. I found that the higher XMAX drivers produced a more natural sounding bass at higher levels. When using a 14mm XMAX driver I found the bass to be "one note-ish" and kind of hollow.

**mrogowski** · **12-15-06, 07:28 AM**

The one-notish sound quality you heard is not from the excursion of the driver, but rather the charateristics of the design and the enclosure the driver was in (if it was in an enclosure at all of course).

Best,
Mark

**Ayreonaut** · **12-15-06, 08:33 AM**

I'll have to agree with Mark. I haven't heard a high-excursion IB to compare, but I hear nothing one-note about my IB 4*MJ18. It has more than enough x-max for clean playback at reference level +10 dB of house curve, in my 1908 cf room.

One limitation of my system is that it naturally rolls off at 16 Hz. I have seen a couple graphs from other IB MJ18 builders and this seems typical. This characteristic of the driver's IB frequency response seems unrelated to its x-max.

**toecheese** · **12-16-06, 12:02 AM**

I'm interested in the 18s- the price is right- but the shipping to USA is insanity.

**toecheese** · **12-16-06, 10:28 AM**

Wrote to Mach5 and they said they'll have a dealer in Maryland in February... not sure if I can wait that long. Watched a movie the other night with the amp turned down and just the one woofer and it was definitely not the same.

**mrogowski** · **12-16-06, 04:01 PM**

Remember, perfection takes time.

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