Crazy 2108 4" question

[Aaron]

I followed Rock Cobbs instructions and used the tone.

Also, I pulled out every last vestige of the foam filter on top of the pole piece using an MEK dipped rag wrapped around my finger...I'm gonna die of cancer aren't I?

[quindecima]

Probably

[speakerdave]

No, but if you're made of glue you'll have only nine fingers.

[Flodstroem]

One idea could be to move a 2123H magnet to a LE8T basket. The important thing when doing that is to reach the same hight over the magnet pole piece in relation of the spider mounting face so you get the same hight over the magnet as in a 2108 motor or same hight as in the 2123H motor. Then one idea could be to use a 2123H cone kit (or an old parted cone from 2123H) and cut the diameter down for the 8" foam surround (for 2108/112A type surround) I dont know if its possible, it depends on the 2123Hś cone angel but that is a simple thing to measure. Then you will get a smaller copy of a 2123H and as a midrange I think its at least as good as an old 2108/112 or maybe better due to the longer voice coil and the Aluminum ribbon equipped voice coil

[bldozier]

As I mentioned earlier the magnet is a different bcd.
if the baskets could be machined I wouldmbe incline to think a transfer would be possible. I took photos of all components on the 1st page.
Brian.

[Flodstroem]

Yes it has to be machined for a new 2123 bolt circle pattern and you have to reuse the LE8T spider because the 2123 spider have a to large diameter
If you could make some type of drill template this machining would be a simple job

[bldozier]

The baskets would need to be widened for the larger magnet, and four screw holes added along with the pin mounting hole. I dont think its to difficult of a job. The rear plate as shown in the photo has the recessed area for the magnet sit.
The area needs to be wider I think a shop could do this work. Then the 3" motor would fit, the 2" motors has some play in the fitting its not super snug. Btw.

[Flodstroem]

The baskets would need to be widened for the larger magnet, and four screw holes added along with the pin mounting hole.

Why does it need to be widened? if the outer rim surface is flat and you have the two pin mounting holes fixed (drilled) then the magnet will sit exactly where it should
What I suggested in my earlier post was the main important thing is: the spiders outer mounting surface hight over the magnet,it has to be checked out (if you choose to use the 2123 cone assembly) It also could be the case that you have to mount some shims for to get the right hight for the spider........
The LE8Tś spider hight (mounting surface) over the magnet seems to be 9.4 mm (or 0.3701") I imaging the 2123 spider sit higher than that?

Now, this is valid only if you choose to use the 2123 cone assembly for to get an 8" substitute for the 2108/112

[bldozier]

Why does it need to be widened? if the outer rim surface is flat and you have the two pin mounting holes fixed (drilled) then the magnet will sit exactly where it should
What I suggested in my earlier post was the main important thing is: the spiders outer mounting surface hight over the magnet,it has to be checked out (if you choose to use the 2123 cone assembly) It also could be the case that you have to mount some shims for to get the right hight for the spider........
The LE8Tś spider hight (mounting surface) over the magnet seems to be 9.4 mm (or 0.3701") I imaging the 2123 spider sit higher than that?

Now, this is valid only if you choose to use the 2123 cone assembly for to get an 8" substitute for the 2108/112

I see, but if the le8t is 9.4mm from magnet to spider, mounting directly to the outter ring would enlarge that number. To use the larger motor the ring diameter needs to be widened and pin holes added, to keep the figure at 9.4mm.

[bldozier]

here is the le10a basket w/ ap motor & the le8t basket w/ the same motor an no seat. See how it sit further off the frame. Is the proximity of the motor height on the frame to the spider not of any importance?

[Flodstroem]

Is the proximity of the motor height on the frame to the spider not of any importance?

Its the most important thing.
If you are going to use the LE10/2123 magnet motor and voice coil with cone you have to check what height there is on the LE10 motor and LE10 spider and apply that to the new 8" basket

The important thing with hight of spider is to have the voice coil in the right position in the magnet gap and not disowned down or upwards.....

[FE3T]

I am looking at the same project but have the type of LE8T basket where the terminals are on one of the spokes, wich sadly enough makes the use of my LE10H motors (the ferrite motor are to large too clear the terminals) impossible without a lot of modifications to the basket. So there is where I am stuck. if I had the version you have I could succeeded.

[bldozier]

Its the most important thing.
If you are going to use the LE10/2123 magnet motor and voice coil with cone you have to check what height there is on the LE10 motor and LE10 spider and apply that to the new 8" basket

The important thing with hight of spider is to have the voice coil in the right position in the magnet gap and not disowned down or upwards.....

Ahhh, I understand now. The le10 baskets do have a slightly taller spider height, with that and the height of the le8t frame without modification it maybe closer to the le10 spider height, true, if we are using the le10 as our measurement in height. The height of the le8 frames 112&2108 included seem to be the same fro. The photos I've seen lower the the relationship to le10a

Fe3t, did you try mounting directly to the frame of the basket with the le10h magnet. Can you tell me the height of the le10h magnet from the spider, the difference...

[FE3T]

If I measure the height from the spider landing to the magnet on the LE8T basket i get 9.25mm or 0.364"

If I just place the LE8T frame on top of the Le10H magnet the height up to the spider landing are 10.9mm or 0.429"

If I measure the height from the spider landing to the magnet on a Le10H basket i get 15.7mm or 0.618"

Measured with some cheap old calipers, so minor faults can occur.

[Earl K]

Can I suggest a redirect ( for both of your energies ).

I understand the desire to create a killer midbass driver / I really do .

The problem here is the 122/2108 magnetic structure uses a .35" thick top plate with a .17" voice-coil centered within it .
- This defines an under-hung voice-coil topology .

The kicker is that these (3" vc style thick ) top-plates were unique to the 122/2108 drivers.

What you're currently struggling to adapt ( the le10 mag-structure ) has only a .28" thick top-plate.
- (IMHO) you won't be able to create an effective ( useful ) underhung vc topology that has enough travel ( Xmax ).

I'd suggest using the complete le8t structure ( basket & magnet ) and utilizing it's super deep top-plate as is ( @ .47" I think ) to create an under-hung mid-bass with a .2 - .25" ( generic 2" ) coil and a generic 8" paper cone.

I think you have a higher likely-hood of creating something worth using going this route ( as well as getting a pro-reconer interested in your project / since you're going to need an infinitely patient professional to supply you with all the "soft parts" )