Removing back chamber from SB26ADC

[skogs]

I want to experiment with different back chamber configurations on the SB26ADC, but i am already struggling with getting the plastic back cup off. I'm guessing heat is the answer, but i'm wondering if there is anything in the motor system that can be ruined by too much heat. If not then i can try baking it at 100C or so. Had no luck with a heatgun so far. The front plate with membrane and voice coil is disassembled prior to this obviously.

Any experience or tips?

 

[AllenB]

Heat is sometimes the answer, however there may be some dacron fill inside. Also, too much heat is not good for magnets.

This driver is unrelated but might be interesting in any case - Removing magnetic shield FE127E

 

[skogs]

Thank you, i might try twisting it off with two oil filter removal tools. Not sure that heat will help then. I used a heatgun until the plastic was uncomfortable to touch, that did nothing. If more heat than that can damage the magnets, then thats off the table.

 

[mainframe99]

While you’re at it, did your sb26adcs have a foam or felt piece behind the dome? Just curious as mine didn’t but have seen others that did

 

[AllenB]

I might drill a small hole or two in the back, careful not to go deeper than the thickness of the cup, and then probe the inside with a piece of wire. Maybe you can saw the cup off.

PS, dont probe straight up the middle because there may be a passage through a vented pole piece straight to the dome.

 

[skogs]

There is no felt or foam to be seen. I've seen pictures of the same driver with felt, so looks like SB have done some silent cost saving. At the bottom of the pole piece i can see there is a gap between the magnet and the plastic cup. So i could saw it off.

What kind of temperatures should i stay below for the magnets sake?

 

[celef]

Please post impedance measurements along your progress

 

[skogs]

I have ordered a DATS V3 measuring tool, I will definatly post my findings when i get to that.

 

[AllenB]

I'm not certain but if I remember correctly about 200-400C could be a problem for a ferrite magnet.

 

[TNT]

I think that mechanical shock is not good either...

//

 

[skogs]

I'm thinking if i heat the plastic cup up to around 150C with a heat gun, then attach a vice to the plastic cup, and use a oil filter removal tool to twist the magnet.

 

[AllenB]

What about sliding a razor blade under the lip, then progressing to a screwdriver? I don't know but I suspect the filter spanner would compress the cup, but it's worth a try.

 

[tamerlano]

on B&W Nautilus a general solution is adopted for the drivers, in fact they use an aperiodic load, where the length of the case is tuned to specific frequencies

 

[skogs]

Funny you should mention Nautilus. I am using B&Ws whitepaper on the Nautilus and 800 as a guideline. I will be 3d-printing different chambers.