Eminence bass guitar CB15, hopelessly "blown"?

[Osvaldo de Banfield]

I never reconed a speaker by my own. It seems to be a patience task.

 

[szegedin]

The Speaker Exchange can usually put together an aftermarket kit. They have pre-defined ones listed on their site for pretty much any Eminence speaker they have worked on in the past (And presumably can still get parts for). Average price is about $75. Some more, some less. You won’t always get exactly the same parameters but if you do get exactly the right voice coil and get the mass right it will drop into an existing cab with pretty much the same tuning. There are likely just a limited number of standard coils that Eminence uses, shared between different models. Much easier for them to source, rather than a unique coil per driver. High frequency response is anybody’s guess - even changing the dust cap will alter that a lot. In many cases, you will get the original manufacturers cone. They get them from somewhere, too.

If you have them recone it, it will be about the same price as the original driver retail. You do that when you don’t know what you’re doing and have an out of production driver that you want back. This is the perfect case for teaching yourself how to recone a speaker. If it goes badly you‘re not out that much money.

Just by shimming with three or four strips of thin plastic or cardboard/thick postcard paper or with the cylindrical shim that comes with some recone kits. You need to shim anyway with a recone kit that doesn't come preassembled to get the VC's position exactly adjusted with the magnet gap height. Afaik most, if not all Speaker Exchange aftermarket kits don't come pre-assembled, but in parts instead.

Best regards!

Seem you have experience. My eternal question about it is how to mantain the coil centered in the magnet's gap?

Indeed, the gap is extremely tight, I can see how a re-cone could be frustrating if it goes wrong. Glad I didn't have to do it! It's not the cheapest learning experience 😉 It would have to be a very good speaker to justify it in most cases. For guitar/bass speakers, I think the used price is usually around the price of the recone kit. After this most recent experience, my preferred strike price for music gear remains $0.

By the way, what is the recommended way to glue a new dust cap on? Cut this one out completely down to the cone, or leave a ridge and rubber cement the new one to the base of the old one? Would be nice to regain some HF response, although frankly I'm please just to have it working.

 

[Osvaldo de Banfield]

Could you remove all particles?

 

[szegedin]

Could you remove all particles?

I'm not sure, but I got a lot of them out, and it fixed the rattle - now it sounds great. I laid it upside down with 30hz going into it and ran a magnet around that gap.

Someone should invent some tool for this job- like a thin magnetic string that can "go fishing" in that gap and pull out particles.
Now I just need to put a dust cap on.

 

[Osvaldo de Banfield]

You can use a small piece of gummed paper to support the original dust cap. With a few of patience...🤔

 

[WhiteDragon]

if the dustcap has a lip on it, usually the typical contact cement, rubber cement or white pva glue since it dries clear.

likely original dustcap is paper without a lip so they use a pva or epoxy type glue with black dye.

any speaker repair vendor will have it.
otherwise using just a generic paper dustcap with a lip on it.
normal white pva glue or rubber cement.

I like white pva since it dries clear and not goopy

 

[profiguy]

The VC former you have is Kapton (polyimide), which tends to blister when overloaded but won't burn readily. Its often hard to tell if the VC was overloaded with a Kapton VC former. If the driver has been thermally abused even just once, it can cause these raised spots to form under the VC windings, sometimes lifting the individual VC windings just enougj to cause a buzz or rattle.

The glue used to hold the VC windings in place is often set with a short burst of high current DC, allowing the assembly to melt the thermoset glue to form a solid unit. Problem is the glue is prone to failing if the driver is pushed too hard despite the high temp Kapton former dealing with the heat. The other issue with Eminence drivers that use a Kapton VC former is the way they run the lowee return lead from the Vc along the gap inside the VC former, which is insulated with a strip of adhesive. I've seen these work themselves loose and rub intermittently on the inside pole piece, specifically on the 2" and 2.5" VCs.

One other problem with Kapton VC formers is they also distort in shape right at the area where the gap is, on the edges where they butt together. Kapton film has a memory that tends to want to straighten itself out when it thermally cycles. This is frustrating when trying to recone a driver and center the VC with shims. Once the shims are removed, the Kapton former edges can spring back and rub on the pole piece. To avoid this, its important to allow the epoxy to fully set before removing the shims and not placing the shims right under the overlap portion of the VC former when gluing the whole assembly together, spider, surround and all.

I dont ever purchase used drivers with Kapton or paper VC formers. This also includes compression drivers, unless i take the time to inspect the VC visually and sweep it beforehand. Its too risky otherwise, because you'll never know if the driver has been thermally abused. When sweeping a cone driver, you want to grab the cone and gently rock it back and forth with both hands to check if the VC is centered well and doesn't easily tip into misalignment so that it audibly buzzes while doing so. If the driver was previously mounted in a cab, it could have distorted the basket frame and cause the VC to rub when the driver isnt torqued down. This also goes for drivers that have been mounted on an uneven surface (thick carpet under the mounting flange) and torqued down unevenly (with excess torque).