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Lee in Montreal
01-16-2011, 11:22 AM
How would this combo differ from an original 2205a or 2225h?

From data sheets, it seems the 2205 is flatter than the 2225 for the same power handling.

TIA

Lee

Eaulive
01-16-2011, 12:17 PM
Since the frame of the 2205A has the same motor as a 2225H frame (1.2T magnet) and that the cones and frames are compatible according to the JBL goes into list, I guess it's safe to say that you will have the performance of a 2225.... if the Alnico magnet didn't lose any of its strength overtime, which they are known for.

Lee in Montreal
01-16-2011, 12:37 PM
My fears are also about the Alnico loosing some of its capacity. Otherwise, the 2205 seems to have different sound specs than a 2225. Lower Fs, and not a cut-off as steep as the 2225's (way more meat below 80Hz and less mids). And the 4530 enclosure was meant for the 2205.

2205 is said to have Fs at 30Hz vs 40Hz for the 2225.

Lee

Eaulive
01-16-2011, 02:16 PM
My fears are also about the Alnico loosing some of its capacity. Otherwise, the 2205 seems to have different sound specs than a 2225. Lower Fs, and not a cut-off as steep as the 2225's (way more meat below 80Hz and less mids). And the 4530 enclosure was meant for the 2205.

2205 is said to have Fs at 30Hz vs 40Hz for the 2225.

Lee

You're right, but to answer your question, a 2205 with a 2225 cone is a 2225. And about the 4530, I read somewhere that this enclosure was very forgiving about the kind of driver used, 2205, 2225, even 2226 I heard can be used with no problem.

Earl K
01-16-2011, 02:21 PM
The "EBP" formula ( Mass Break Point formula ) will help tell the story in how the voicing of the two speakers will be different .

(A) The formula for EBP is ;

( BL squared ) / ( 2*Pi*Re*Mms )

Notes ;

(i) Mms is expressed in Kilograms
(ii) The answer is stated in Hertz

(B) Example ;
- A new C8R2225 kit in an older 2205 alnico assembly ( partially demagged ) might give an EBP value of ( here I chose an arbitrary BL factor of 20 as a guesstimated value ) ;

( 20*20 ) / ( 2*Pi*6.3*.105 ) or,,, 400 / 4.156327081 for an EBP of ; 96.24 hz

versus ( a brand new 2225H ) of

( 23*23 ) / ( 2*Pi*6.3*.105 ) or ,,,, 529 / 4.156327081 for an EBP of ; 127.28 hz



BTW ; the 2234H ( using 120 grams as the Mms value ) has an EBP value of @ 92.9 hz while the 2235H is 72 hz .



- EBP is a handy starting point to predict the "voicing" of a transducer .
- With enough experience under ones belt one can see what the likely LF limit will be for a woofer .


<> cheers, EarlK

Lee in Montreal
01-16-2011, 03:09 PM
Hi Earl.

Interesting aspect indeed. So, where does "predictability" start? Below or above that calculated value?

Earl K
01-16-2011, 03:53 PM
It's easiest to use a simplistic analogy and compare the speaker motor to a car engine .

Most understand that any engine/drive-train has a sweet-spot where it likes to operate .

Simplistically, one can look at the EBP as the mid-point ( or median value ) of the transducers optimal operating range ( or torque curve ) .

FWIW, WinISD Pro calculates the EBP ( it places the value in the "advanced tab" of the TS parameters window in the Drivers Editor ).

I recommend playing around with WinISD Pro and entering a range of different BL numbers ( you must allow the program to auto-recalculate Qes, Qts, Vas ,,, or else it's "auto-check" feature won't let you save the new TS parameters / since they will be bogus ).

Once you have these new TS parameters, you can play around with different alignments using your new "Franken" woofer and observe the predicted LF response .


<> cheers

Lee in Montreal
01-16-2011, 04:08 PM
Thanks

toddalin
01-17-2011, 09:50 AM
I had OCS redo three 2205s as AlNiCo 2235s and had the magnets recharged. When we put one on WT-2, it "speced out" as a 2235.