Help with a Hartsfield Tweeter mod.

[SureFire]

I have a pair of vintage Hartsfields with 150-4C Bass driver and 375 driver with H-5039 exponential horn and Koustical Lens and N-500H dividing network. This is in a early large folded horn enclosure, not the classic Hartsfield. To improve the top end I would like to install a pair of tweeter's. Any idea's which would be best? 075's? 077's? 2405's or ?? What cross over would be best and at what point?:)

[Rolf]

Hi, and welcome!

077 and 2405 are the same. (Public/Pro versions) I suggest one of those over 075. Crossover about 9000Hz

Regards

Rolf

[SureFire]

Thanks for the info Rolf. I have access to a pair of L-65's with 077's and the crossovers. Will the stock L-65 crossover work at 9000 Hz and up?:)

[Robh3606]

No it crosses to low and will pad it down too low. A simple 1st order with a cap may work better. The 2440 will rolloff above 10k. Looking at an old Pro Note from JBL they suggested a 1.5UF.

Rob:)

[SureFire]

Thanks Rob for the info. Is there a list of recomended stock JBL crossovers that I can use on the 077's and still keep my N-500H for the other drivers. Also, mounting the 077's, I have a pair of 075 brackets.....where would be the best place to mount them, directly above the 375's, beside, under or ???:barf:

[Robh3606]

If you look in the 1979 components catalog take a look at the N7000. That looks to be the suggested crossover.

http://www.lansingheritage.org/html/jbl/catalogs/1979-comp.htm


Schematic here if your inclined to build.

http://www.jblproservice.com/pdf/Network%20Schematics/N7000.pdf


I would try the series cap first as it is quick easy and may do the trick.

Where to place the 077/2405 ????? Not sure I have seen them on top. Under might make sense. The 2405 is directional so I would try to have them set-up at close to your seated ear height if that's possible. I also wouldn't do a thing to original cabinets that would decrease their value.

Rob:)

[GordonW]

Truthfully, I'd be inclined to find/build a pair of Angelus enclosures... these were made, back in the same era as the early Hartsfield, to place an 075 bullet tweeter on top of an existing cabinet. Here's a link to the catalog page, showing the Angelus (on the right side of the page):

http://www.lansingheritage.org/images/jbl/catalogs/1957/page7.jpg

You could easily put 077/2405 slot tweeters and N8000 crossovers (I'd use the N8000, instead of the N7000... the N8000 was MADE for the 077/2405, while the N7000 was made for the 075/2402 bullet) in the Angelus cabinets... it'd literally be a bolt-in...

Regards,
Gordon.

[Robh3606]

"(I'd use the N8000, instead of the N7000... the N8000 was MADE for the 077/2405, while the N7000 was made for the 075/2402 bullet)"

That may be true however that is not what JBL reccomends to use with a 375 midrange. The N8000 is set up to be used with the Le-85. Take a look in the catalogs.

Rob:)

[toddalin]

I have a pair of N7000s sitting on the shelf I could part with, not cheap but reasonable.