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miatagreg
08-25-2004, 08:32 PM
I recently acquired a pair of C-50's with the 8SR speaker group.I was thinking about moving one of the 075 tweeters in order to make the speakers a mirror- image pair.I would welcome your comments about this and also help in accessing the inside of the enclosure,as the 075 is mounted from the inside of the baffle.Is the inside of the enclosure accessible from the bottom?Help!:confused:

LE15-Thumper
08-25-2004, 09:05 PM
Usually most of the work is done with the woofer removed for access to the inside of the box. Also, some of those cabinets had removeable backs.

Anyone please elborate or correct me if I am wrong.

HTH

miatagreg
08-25-2004, 09:15 PM
Thanks for the info Thumper.I tried removing the woofer.It is VERY securely attached to the baffle....it almost appears that the cork attached to the back of the speaker rim is glued to the baffle.After rimoving all of the mounting screws tried to gently pry it away from the baffle but I got concerned that I might damage something.Any ideas?

Zilch
08-25-2004, 09:45 PM
I've never seen a C-50 with removeable back or bottom.

The woofers do take a "seat" with the cork over time, but they can be persuaded loose. Use a wider, thin, beveled tool, like a painter's "5 in 1" tool to distribute the pressure and not damage the frame or baffle. The cork usually remains intact....

While you have the woofers and passive radiators out, consider refoamng them to restore the bass response. If they are original, it's unlikely they retain their requisite compliance. Your JBL Service Center can advise you regarding their condition. Have them look at the spiders, as well....

Mirror-imaging them is a worthwhile endeavor.

miatagreg
08-26-2004, 06:33 AM
Thanks Zilch!! I appreciate the info and I will give your method a try.As to the surrounds, they are not foam but appear to be treated fabric.They are fairly compliant and appear to be in good condition.Should I still consider replacing the surrounds?

Thanks again....:)

Zilch
08-26-2004, 09:35 AM
Originally posted by miatagreg
As to the surrounds, they are not foam but appear to be treated fabric.

S8R should have LE15A woofers and PR15 passive radiators. The original surrounds would be light-colored kinda rubbery-looking foam. Typically, these harden and crack over time, requiring replacement. The best choice is new foam surrounds to restore the original performance.

It may be that your surrounds have already been replaced with fabric ones, or you have different woofers, perhaps LE15B, which do not have the foam surrounds. See what the actual models are once you get them out, from the labels on the backs of them, and maybe post a pic here of the surround for the forum to review.

I wouldn't replace anything until you know what you actually have, and the condition. This is kind of a diversion from your original intent. It may be that it's all good, but, for your own satisfaction, it may also be important to know what's going on there....

miatagreg
08-26-2004, 09:51 AM
I took a closer look, and the LE 15 does appear to have a foam surround.The surround on the PR 15 is a reddish brown color and looks to be a resin treated fabric.I will remove all and have them reconed.The surrounds on the LE 15's are rather stiff.Thanks again for your help.:)

Zilch
08-26-2004, 10:20 AM
Originally posted by miatagreg
I will remove all and have them reconed. Just reFOAMED. ReCONEing them gonna be WAY expensive, and likely unwarranted....

The PR15's with fabric surround are probably fine.

NOTE: JBL does not sell just the foam surrounds. It's gonna be an aftermarket deal, but it's commonly done with successful result....

miatagreg
08-26-2004, 11:37 AM
Oops...I did mean to say refoamed....the cones are in very good shape....

I continue to marvel at how good the c-50's sound.I have been involved with audio gear since 1970 and have owned lots of speakers.They may not have the most accurate sound available,whatever that means.But boy they have dynanmic range like I have never experienced.And the imaging is first rate.It's as good as my Apogee ribbon hybrids,which are well known for pinpoint imaging and soundstage depth.

Thanks again for your invaluable advice.

Greg:)