Peerless dust cap removal

[ashok]

I have a Peerless 850490 8 inch bass driver. I wnt to remove the dust cap without damaging the cone.
Would anyone know what solvent will soften the glue used to stick the dust cap ?

Looks like a polypropylene cone. Will Benzene or Acetone damage the cone material ? The dust cap seems to be paper based (?).

Thanks .

[pinkmouse]

It's always a bit iffy working on a speaker where you don't know the adhesives used, but I would try gentle warming first to see if that softens the glue. I use a hot air gun, but I've had practice, I recommend a hair dryer, or a temperature controlled soldering iron with a wide bit set to very low and rubbed gently along the join. If that doesn't work, you can start on solvents, but try them with a tiny amount on a test patch first. I've had most luck with acetone applied directly to the seam with a 000 size artist's paintbrush.

Whatever you try, work slowly and carefully - patience is definitely a virtue here.

[ashok]

Thanks for the suggestions.
I'm afraid of the hot air gun as the cone is plastic. I do have a temp controlled hot air gun !

I have Amyl Acetate and Benzene and Xylene right now. If they are no good I'll have to get a bottle of Acetone.

On the topic of solvents. I found some liquid 'enamel remover' for enamelled wires. It is pretty corrosive I think . Any idea what chemical it could be? It's looks almost like petrol in colour.

I'll report my progress on the cone. I want to take off the dust cap as I intend replacing it with a metal plug. I think the dust cap introduces some 'cuppy' sounds as the frequency goes up.

Cheers.

[AndrewT]

Hi,
the dust cap does what it says on the box.
It keeps dust and debris out of the pole gap.

[David Gatti]

I removed the dustcap off my old dynaudio 21w54s (polycone with inverted dustcap) just by using a sharp blade and carefully lifting up the joint. No solvents were necessary.

[ashok]

I used a small paint brush to apply Amyl Acetate along the joint of the dust cap and the cone. After 15 minutes I tried to lift off one corner with a sharp blade ( typical box cutter blade ). It did lift off but the glue layer did not lift off together ! I noticed that it looked like a rubber based glue. So I then applied Xylene all round and waited for half an hour and then applied some more again. After some time I lifted off the dust cap by going round with the blade and made sure that it came off 1mm at a time.

You can see the end result. The good thing about this was that the dust cap is fairly intact except for some patches where I was in a hurry and some fiber layer has peeled off. The exposed side looks fine . So I can put it back if I find that it has not helped.

Thanks for all the suggestions.
Cheers.

[pinkmouse]

Originally posted by ashok
...the dust cap is fairly intact except for some patches where I was in a hurry and some fiber layer has peeled off...

What did I tell you!

[ashok]

I couldn't wait again !!

First I tested the driver in as is condition without the dust cap.
Lots of resonance in the open voice coil area.

Next I put in a nail polish bottle over the pole piece. The only thing which approximately fit in there.

Much better sound. Far better than with the dust cap in place.
So I'm happy the effort was worth it. Now the dust cap will not go back on. I'll have to deal with the dust problem , but no more dust cap here. I'll have to try out several different phase plugs to see what sounds best.
Any suggestions guys ? I've seen several different types being used by manufacturers. I will be making it out of aluminum.

Cheers.

[ashok]

I just noticed that the cone has small holes at its base. That is an air leak between the front and rear .
I plan to use the driver in an open baffle configuration.

Would anyone know how this would affect the performance ?
At higher frequencies it shouldn't matter much I think. But at low frequencies could it generate noise ?
I'll have to run a frequency response check. Heck , that's a lot of effort right now !

[rl guy]

hi, very interested. you mentioned that it sounds much better. what frequency range benefits the most and what freq. benefit the least?

i have the NHT m5 with the peerless 5.5". i'm also interested in removing the dustcap if there is benefit. however, the peerless 5.5" is crossover at 400mhz.

thanks for your time.

Originally posted by ashok
I couldn't wait again !!

First I tested the driver in as is condition without the dust cap.
Lots of resonance in the open voice coil area.

Next I put in a nail polish bottle over the pole piece. The only thing which approximately fit in there.

Much better sound. Far better than with the dust cap in place.
So I'm happy the effort was worth it. Now the dust cap will not go back on. I'll have to deal with the dust problem , but no more dust cap here. I'll have to try out several different phase plugs to see what sounds best.
Any suggestions guys ? I've seen several different types being used by manufacturers. I will be making it out of aluminum.

Cheers.