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Jakob
10-19-2005, 03:07 AM
I have to start with something and I don't count on getting it a 100% right the first way around, I'm just asking for something to start out and experiment with that doesn't make me :barf:
According to some tests done on this forum the 2"-drivers starts to drop below 1kHz, and the 15" drivers get really "beamy" above 1.2kHz, so should a crossoverpoint somewhere in between be optimal?

Would it be worth looking at the Everest-network or maybe even the 4430?

Is there a kind of general formula for this kind of driver setup: 2nd order for the woofer and 3rd order for the driver f.e. or what would You recommend?

What impedance should be used in the calculations? To get it accurate, I guess you should use an average of the impedance at the intended crossover slope?

I would also want to know more about "shelving networks", how You lower the overall sensitivity of the driver, but get better high frequency capabilities.


Is there any good shareware or site to help You calculate crossovers?

Wow, that is a lot of questions.:o:

Any help greatly appreciated!

Thanks: Jakob

Earl K
10-19-2005, 04:33 AM
Hi Jakob,

(A) I've scanned all your old posts & here's the necessary info summary that I'm proceeding from ;

(i) You own a pair of 250ti(s)
( So why mess around with this other stuff ? / no need to answer )
(ii) You built a pair of 18" sub boxes but I'm not clear if they are loaded with 2245h(s) or anything for that matter. Since you were inquiring about tuning 2242 woofers back in June - I suspect you never did loadup those 140L sub boxes .
(iii) You messed around with a 2110 8" mid for some reason . I think you thought that a 4430 could be improved upon by adding an Audax style mid to it. I forget if you actually have a pair of 4430(s) .
(iv) You've owned or still own 2405 slots and are aware that a higher crossover point sounds best with them .
(v) As recently as two weeks ago you were looking for a pair of E145s.
- I guess you actually obtained some .
(vi) This summer you bought some 2441 drivers with what are likely 2445 diaphragms. They have a darker sheen than aluminum . ( You should have published some pics with your question in that thread. )
(vii) You've previously articulated your desire to build something like what John W created ( as well as his 1" Smith horn ).

(B) Here's my Conclusions :

(i) What to build ?
- Build something patterned on what John W has built .
- Use his cubic dimensions and box tuning .
- Prepare to build some 18" subs after that project is finished if you want bass that rivals your 250ti speakers .
- John W(s)' 3-way Project (http://audioheritage.csdco.com/vbulletin/showthread.php?t=5951&page=1&pp=40)

(ii) What crossover ?
- Use the modified N333 that Giskard posted somewhere in the archives .
- John W used this. It's a three way and should work with a 2441. Any necessary changes should be limited to load resistors in the horn circuit .


(iii) Sharware ; Crossover Calculators ( to design your own custom filters )?
- Forget about it . JBL components of all sorts need specially designed "contour filters" blended with the Classical Transforms ( Butterworth , Bessel , LR ) to be used in a HiFi setting .

(iv) You haven't mentioned what horn you are going to use in your project .
- If you have no horn at this time then obtain/build some 2" Smith or Westlake Horns .
- There is no 2" version of the Everest Horn or the H3100 / though maybe you could employ MatthiasA to design/manufacture/kludge one together for you.


:)

John W
10-19-2005, 08:23 AM
I have since swapped out the 1200hz smith horns with full scale 2397 replicas built from heavy beach-wood driven by 2440s. These mate very well with the E145s.

The original project only uses the high pass section of the N333 to cross over the mid and tweeter. I am using an 5234 active crossover with an 18db slope at 800hz to the E145 and a shallower slope to the N333 for the mid and tweeter section, sort of like the 4430 card.

Anyway, if you want to experiment with differing crossover points for the two drivers I would suggest trying to track down an active crossover like the 5234 and bi-amping. Its fairly cheap and easy to fabricate the cards for the different crossover frequencies, especially compared to experimenting with large crossover inductors and caps.

If you do, just remember to put a nice large cap in series with the 2441s to protect them from any turn on surges.

Earl K
10-19-2005, 08:35 AM
Hi John

Nice to hear from you . :)


I have since swapped out the 1200hz smith horns with full scale 2397 replicas built from heavy beach-wood driven by 2440s. These mate very well with the E145s.

- Did you make these full scale horns ?
- I always love seeing pictures of your work :D

Cheers

John W
10-19-2005, 08:39 AM
Thanks, and yea they were put together in my trusty workshop. I will post a picture tonight.

Earl K
10-19-2005, 08:43 AM
Thanks, and yea they were put together in my trusty workshop. I will post a picture tonight.

Wonderful ! :p

Looking forward to some new pics . :applaud:

Jakob
10-20-2005, 03:07 AM
Earl K,
Thank You for your comprehensive answer!

Ok, I will try to clarify my intentions with this project. I did load the 140l boxes with a pair of Italian Ciare-woofers. They sound very nice, but running them with my 250 tis, they never get to move a lot of air (there is a difference of about 8 dB in sensitivity). To get the most out of my woofers (and I also have a pair of basshorns I need new mids and highs to,) I decided to build something with a 15" and 2", the 2405's I already have.

So, I borrowed boxes with a JBL 2227H and a B&C 2" driver from a speakershop and I guess I found almost what I was looking for. Though the 2227 lacking midbass made me search for other suitable 15" drivers. I decided to get a pair of E145 to try out, and they are on their way (thank You George).

The 2441's I got was loaded with 2445 dia's (they will do for now) and I will use stereo lab's tractrix horns.

Thank You Earl and John for the info. I will look into it right away!


Thanks!