My right woofer sounds different from my left?

Corbin Johnson · « **on:** 23 Aug 2004, 02:56 pm »

This weekend I was going to replace the fiberglass with lambswool when I noticed that the rubber seal was loose from the metal frame on my right RM40 speaker's lower woofer. This probably happened when I changed my caps a few weeks ago. I heard a slight distortion after the cap upgrade, but reinstalled the woofer and it went away.

I thought before I replaced the woofer I'd try regluing it my self. The rubber was both loose from the cardboard rim and the metal frame for about 20 degrees, so I pulled both apart and applied Goop glue to the metal speaker frame and glued the rubber diaphram back in place and then glued the cardboard ring on top of the rubber gasket. This seemed to work great. When I reinstalled it I inadvertently but it back into the left speaker. For the first time I noticed much deeper bass coming from the left speaker and it sounded great. So, I checked the right speaker's lower woofer to see if that diaphram was loose and it was, but only slightly from the frame, not the cardboard ring. I pulled this one and reglued the entire rubber diaphram and cardboard ring to the frame. When I reinstalled it, it sounded the same as before, not as deep as the other.

Then I switched the left woofers to the right speaker and vice-a-versa and the sound was what I rembered, with deeper bass from the right speaker, balanced with the bass from my larger sub next to the left speaker. But this exercise made me realize that the two woofers do not sound the same. I don't think my repairs made any change to the sound. Could it be that the right woofer is broken in more since the right channel typically sends more bass? Did I maybe tighten the diaphram more on one speaker than the other during the repairs, although I don't think they sound any different than before? My speakers are 1-1/2 yrs. old. I didn't notice any air leaks even though I had to reseal the right woofer twice until I didn't feel any air leaking around the seal to the cabinet.

Adding and subtracting putty didn't make the two sound the same. I don't have a problem with the sound, just wondering how I could make both woofers have deep bass. This way I wouldn't even need my larger sub for stereo to sound balanced. Any thoughts would be appreciated.

Thanks,

Corbin

Brian Cheney · « **Reply #1 on:** 23 Aug 2004, 03:42 pm »

Several years ago our then-assembler was not applying adequate amounts of epoxy to the surround/basket and surrounds were pulling loose. Regluing solves the problem but if you want to send in the woofer with the lower lowbass output we'll check it out. Send to Itone Service, 2031 Rumrill Blvd #6, San Pablo CA 94806.

Corbin Johnson · « **Reply #2 on:** 23 Aug 2004, 04:36 pm »

Thanks as always Brian. I'm going to listen to it a while longer and maybe I'll send it in for checkout in the future. The difference is subtle and not noticeably apparent. I'll keep tweaking and let you know.

Corbin

Corbin Johnson · « **Reply #3 on:** 24 Aug 2004, 01:56 pm »

Yesterday I took the lesser woofer apart again and reglued it in two steps just as I had done the other. It made a slight improvement, so I think both woofers are fine now. I'm done tweaking. I don't plan to try the lambswool since I have everything sounding wonderful and don't want to risk another screw up. Man do I love the auricap upgrade!

Thanks for the help.

Corbin

ekovalsky · « **Reply #4 on:** 24 Aug 2004, 05:45 pm »

Corbin, the chance of having another "screw up" by putting in the lambswool is about zero. The woofers are definitely on the fragile side and it is best to not manhandle them. The neo mids are much more robust... unless one is careless and sticks a screwdriver or other sharp object through the grill or breaks off the connection board

I doubt you will see a dramatic improvement from the lambswool but it is probably worth the modest cost of the material and the effort involved in putting it in. By far the hardest part of the upgrade is screwing and unscrewing the neo panels (four screws each) by hand. I didn't dare use a power tool and definitely got a good forearm workout!

audiochef · « **Reply #5 on:** 24 Aug 2004, 06:29 pm »

Corbin,
glad you're liking your cap upgrade. See if you can agree with me that they actually take along time to break in and get better.

After about a year now with my Auri upgrade, current system and surroundings, I find my RM40s still unmatched by most anything else I've ever heard. Including the Dali-Megalines I listened to last week in the south bay. They may have had tighter bass at the expenss of discontinuity with all those drivers though.

I've just varified this claim by letting my system rip ,as the wife and neighbors are away at work. I was like the "Maxell man" gripping the armrest and all.

Someone just posted that he purchased another speaker over the 40s for some silly reason, boy did he ever lose out. He'll never realise what a mistake that was.

Well I hope he's enjoying those ordinary speakers.

JoshK · « **Reply #6 on:** 24 Aug 2004, 06:37 pm »

As far as screwing and unscrewing the midpanels, I used a cheap $20 B&D cordless screwdriver. It really isn't powerful enough to jump off or strip the heads and then I tightened the last bit by hand. This sure did save a lot of time and forearm workout!

Corbin Johnson · « **Reply #7 on:** 24 Aug 2004, 08:08 pm »

Eric,

I'll probably get the nerve up to try the lambswool in the near future. My concern with removing and reinstalling the woofers is now that I've reglued the rubber diaphram I have to be very careful that the screws don't grab the little bit of rubber that protrudes around the screw holes, pulling a kink in the surrounding diaphram. I've already made this mistake once and had to pull the woofer apart again and repeat the regluing process.

A couple of questions on the lambs wool. How do you know when you've installed enough or too much? Could the difference in sound just be from packing in more or less lambs wool than original fiberglass? Can you pack too much in? Is the improvement really worth the effort or in my case the risk that I might have to reglue a woofer again?

Thanks,

Corbin

ekovalsky · « **Reply #8 on:** 24 Aug 2004, 08:19 pm »

No need to worry about the woofers, you won't have to touch them. The midrange drivers are in their own subenclosure, all you have to do is unscrew the panels and swap out the fiberglass behind them for the wool. The midrange panels are held in by four screws each which go through the metal case. Worst thing that can happen is you strip a screw, but you can buy a 20-pack of identical replacements at Home Depot for about a buck.

I found it pretty easy to put in the right amount. You want to pack as much in as possible without it protruding through the opening on the baffle. You have two pounds total, divide it in half so approx one pound goes in each speaker.

The whole job should take about 20 minutes per speaker.

Fiberglass is superior to wool around the woofers, so again no reason to mess with them.

jgubman · « **Reply #9 on:** 24 Aug 2004, 08:28 pm »

Don't replace the fiberglass around the woofers, only the fiberglass behind the midrange subenclosure.

Corbin Johnson · « **Reply #10 on:** 24 Aug 2004, 09:49 pm »

Thanks! This sounds simple enough.

Corbin

doug s. · « **Reply #11 on:** 25 Aug 2004, 09:34 pm »

has anyone tried blackhole-5 instead of fiberglas or lambswool in this application?

thanks,

doug s.