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mbeards
11-21-2013, 04:11 PM
Hi Everyone,

I have asked this question once before without great response so I figured I would ask again...

I am now at the point where I am finishing up my stereo Hartsfield pair and am again thinking about bass woofers and crossovers.
Right now I have a pair of 130A woofers which I plan to swap with other 15" drivers for find what I like best. I fear the 130A cones my be to compliant for a horn loaded enclosure. (Also one suspension is much stiffer than the other so I doubt they are well matched)

My question is, what would be some other good woofers to try and swap in?

I do not have a wide range of experience with the JBL product line and could use advice from someone with experience. The 150-4c's are not an option, at least for now due to thier cost and I am willing to bet that most are tired and worn out since cones are unavailable. Also, it is difficult to find a suitable replacement without experience since there are no published or measured Thiele/Small parameters.

If anyone has woofers that may fit the bill and are willing to part with them, let me know.


As a side note, I have started to model the 130A speakers with my 3115 crossovers in Cadence using the approximate parameters found here:
http://www.jblproservice.com/pdf/thiele small parameters/theile parameters.pdf

The response is very peaky (+5dB at around 200Hz) with very nonlinear phase response.
I recently acquired the Dayton Audio DATS speaker test system which I will use to to characterize my final woofer choices and optimize crossovers.


Thanks for any help,
Matt

Robh3606
11-21-2013, 08:32 PM
Just use E-145's and all is good

Rob:)

subwoof
11-21-2013, 10:03 PM
2227H's if you can find them. These are JBL's last and best drivers meant exclusively for horn-type apps.

sub

Mostlydiy
11-21-2013, 10:40 PM
There are loads of diffent drivers to try out, the 2227 beeing the last of the original old "big motor light cone" heritage. If you have access to any of D130, K130, E130, 2135, 130A, 2220A/H, I would start from there. Maybe even the D,K,E 140 might work. They have a lower Fs though which will work against them in this application. (Often its newer = better so 2227H might be the best bet but I think that 2220A would be a real killer)

/Mostly

more10
11-23-2013, 07:40 AM
Just use E-145's and all is good

Rob:)

This is what I also have heard. I got my pair from a guy who planned to build Hartsfields, but gave up and build the other famous but inferior old school corner horn.

mbeards
11-23-2013, 10:57 AM
This is what I also have heard. I got my pair from a guy who planned to build Hartsfields, but gave up and build the other famous but inferior old school corner horn.

The Hartsfields are not for the faint of heart!:)
The wood work and geometry involved to do it right is mind bogging!

Any chance that you would be willing to sell your pair of E145's?

Matt

more10
11-24-2013, 08:59 AM
Any chance that you would be willing to sell your pair of E145's?


I have great difficulty parting with JBL drivers :), and shipping them across the Atlantic will be a bit expensive. I have to decline. Sorry.

JUNGLECATGEORGE
03-21-2014, 11:51 AM
i am using d 140's they seem to be ok. i tryed e 140's but the magnet wont fit properly in the cavity

Horn Fanatic
03-30-2014, 06:08 PM
What I have found through countless calculations is a simple indicator, but not the only. The Efficiency Bandwidth Product. The higher the number the smaller the chamber the speaker can reside in. The 130A / 2220A for example, work well in an chamber of approximately 2 cubic feet or slightly less, with a throat area of approximately 54 square inches. I loaded a K-Horn with a 2220A some years ago, and it performed admirably. The D130 would like to see an ever so slightly larger enclosure, and ALTEC woofers typically want to see between four and six cubic feet, and more. Remember the A7 and A11 enclosures? Lotsa volume with a short horn.

The Top Loader C30 had the smallest chamber I've ever seen to house a 15 inch driver. The chamber volumes for the Paragon, as well as the Coffin Back C30 are larger, and in turn have larger throat areas. The criteria for choosing a horn loadable cone driver however, goes far beyond the EBP. I typically like to design my folded horns for increased bandwidth rather than efficiency.

I wish that someday someone would take Thiele-Small Parameters on the 150-4C, because I would love to know what made that speaker tick. I feel that the 150 was the best cone horn driver ever produced, and why JBL chose to load the Paragon with the LE15 is truly a mystery. I'm glad the Hartsfield didn't suffer the same fate. I had the opportunity to reload a Paragon with a pair of 150-4C, and the difference between those and the LE15 was like night and day. Loading an LE15 in a horn enclosure allows it to produce mushy, ill-defined bass, flawlessly!

I don't consider the 140, and especially the 145 suitable horn drivers either. John Wolff at Classic Audio Productions uses the TAD woofer in his Coffin Back re-pro, but that model doesn't impress me either. I cringe when I see a 2226 in a Hartsfield, I have seen them on Ebay. I also cringe when I see folks using the D140 in the C55 enclosure. JBL didn't load the rear loaded horns with the 2220 for laughs. It's the correct driver the company had for that design. I can only imagine how well the box performed loaded with the 150.

I have been searching on the internet for several years to find a manufacturer who could produce a 15 inch driver that had the same or close T-S Parameters as the 130A / 2220A, but I have had no luck. If I could find a current production 15 inch driver that could perform well in a C34 or a K-Horn, I would definitely use it. I use those two designs as a base of reference.

I think using any JBL speaker in a Hartsfield or Paragon other than the 150 or 130 is nothing but a compromise in performance, although I haven't been introduced to the 2227 yet. It's the 4 inch voice coil that is a key factor, and there are few manufacturers making drivers with 4 inch voice coils that are suitable for horn loading. Nearly all manufacturers are making speakers which have mega-watt handling capabilities, which isn't necessary for domestic use.

Regards,

H.F.

P.S.

I just pulled up the data sheet for the 2227. I'm impressed! 100dB Sensitivity, low Q, EPB @ 181.8. The EBP for a 2220 is 205.5. An educated guess is that an fc of around 37Hz would make the 2227 driver happy. The Xlim excursion scares me, 2" ? I agree with subwoof & Mostlydiy, that the 2227 would be a safe bet for a horn enclosure. If I were to load that driver in a Hartsfield I would calculate the proper chamber volume based on the existing throat area to achieve reactance annulling. The existing Vb may be correct, but it never hurts to check.

Regards,

H.F.