reconing 2220

[jaybird]

I read a thread that subwoof posted in 11/03 that stated you can't recone
2220's into 2235's, (deep gap types). Was he talking about pre-assembled oem kits or would it be possible to do it with aftermarket parts from scratch and get an acceptible result?

[Earl K]

Don't do it unless you're into making a "one of a kind" franken-woofer . :blink:

- While an experienced and motivated reconer could get the 2235 kit to fit properly ( the whole shebang needs upward shimming to center the coil in the deeper gap ) - your new hybrid will have sonic characteristics you'll probably not really appreciate ( since you seem to be after the deep-bass authority of a 2235 ).

- A higher Fs, more midrange output, with an overall "voicing" that is tilted into the bass/midbass area are just a few examples of the changes to expect.

- And then you'll also need to pay someone to run new Ts parameters for you, assuming you want to do some meaningful system tunings for this project woofer .
:cheers:

[GordonW]

Yeah, I'd be looking to find someone willing to trade you a 2205 or 2225 for the 2220. Those things seem to be pretty common. Then, you can properly recone it as a 2235 (correct magnet assembly)...

Regards,
Gordon.

[jaybird]

Thanks for your replies, but I was planning on assembling with aftermarket parts and centering the voice coil by hand. Know anyone with 2205 baskets??

[subwoof]

Actually you would need to shim *down* the cone to re-center the coil in the gap since the 2220 gap is deeper ( and therefore the center of it is further away from the magnet mounting surface ).

This of course isn't practical. I did have a machine shop mill down the entire surface of a ferrite 2220 magnet once ( while still magnetized ) to see if it would work.

Boy did I piss off a bunch of machinists - seems that every bit that touched it became magnetized and the iron "curlys" stuck themselves all over that poor bridgeport...

:)

Since the frame's ribs meet at the magnet mounting surface, there isn't enough material to spare.

sub

[GordonW]

Well, if you're making a 2220 frame into a FrankenWoofer anyway...

A 2240 voice coil has the same winding length as a 2235 (3/4"), just on a 1/4" longer former. This could allow shifting the coil downward in the gap, getting it centered vertically.

With the 2220 basket, if you were to use an aftermarket 2235 cone, spider and dustcap, and 2240 voice coil, you should be able to at least get a woofer that was "functional", in a non-misaligned-coil standpoint. It'd still have WAY different parameters than a standard 2235, though... as was said, it'd be higher efficiency, more midrange, but less low bass extension.

Another possible option, that MIGHT wind up giving parameters CLOSER to a standard 2235 (ie, less midband output and more low bass), would involve using an aftermarket 2245H voice coil, with the 2235 cone and spider, and a slightly bigger dustcap (a 4.406" cap rather than the "standard" 4.125" cap). The 2245 coil has a 1 inch long winding rather than the 3/4" winding of the 2235; this could "counteract", at least somewhat, the X-max-reducing effects of the thicker magnet top plate. The potential downside, would be that you would slightly reduce the available mechanical travel, before the coil former bottomed out into the rear plate; but, you should be able to get a woofer that would at least be MUCH CLOSER in parameters to a 2235H. Maybe the resonance might be a bit lower (due to the heavier voice coil assembly), the Q would probably still be slightly lower (due to the thicker top plate)... and those parameters might just "offset" enough to give about the same bass extension and efficiency in the same size box...

All of this is total speculation, though... until someone tries it. And I definitely won't be responsible if the results don't pan out. But, if you've got access to aftermarket parts, that's the best plan I could come up with given that basket and the stated goal...

Regards,
Gordon.

[tomt]

Earl K Don't do it unless you're into making a "one of a kind" franken-woofer
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

the real point here i feel is being overlooked
while the members of this forum have only
the Best intentions for you and every one
a stronger warning should be announced.

the creation of some thing so un natural
will have serious and quite dangerous
side effects(post #5)
subwoof got off easy- he's not even dead'
but you know were that could have lead
to.

http://www.filmsinreview.com/Images/A_G/frankenstein.jpg

and ultimately

well you know

[duaneage]

You can't make a race horse out of a mule. Buy the driver that works and Epay the one that doesn't

[jaybird]

Thanks for all the wonderfull info, all this hard speculating caused a pair of 2235s to pop up out of nowhere so I think i will put the 2220 kits in and leave things as they should be. Now I.need plans for B380s!

Is it true Peavey 1501 and 2s make great 2235s??? LOL!