Audio Asylum Thread Printer

Get a view of an entire thread on one page

FAQ / News / Events

High Efficiency Speaker Asylum

Vintage Field coil woofers in Reflex?

58.106.55.35

Hi everyone.I was going to buy jbl D123's But now I am wondering if I can enjoy some feild coils more. I just picked up a JENSEN F12-N Field Coil 12" Seemingly good condition too test. All I have is some huge well built reflexes with 15inch passives.I made them for jbl s8'r with 15's years ago.(I have a je lab ob to try but I am thinking that wouldnt work). I have axiom 301's mounted on baffle plates in them atm. There a little sloppy with my sloppy tube amps(think tubes an EI cores).I have been surprised by MI drivers with my tube amps before thus the interest in the D123's Most would understand why so I wont go into it. The enclosures are very good and inert.Of course I could seal off the passive.Internally they measure 490mm*440mm*750mm. I have searched this forum for anything on feild coils.I note most ppl are using them with other bass or horns.

I all so note the Magnavox 15's are probably more suitable for reflex bass if any are.Is there any chance of using JENSEN F12-N Or any other vintage fc for that mater in reflex or sealed perhaps with a inductor and resister to shelve the response.Or am better getting D123's.... Thanks for looking ppls.

Follow Ups:

F12N in a box - sser2 11:32:29 07/02/07 (7)
F12N is a wonderful midbass driver. However, don't expect low bass out of it as Fs is about 60 Hz. BTW, 15" Magnavox FC is also about 60 Hz.

Another problem is field coil heat. If run as recommended, F12N FC dissipates 25 W. It is even better at 40-50 W. In an enclosure stuffed with fiberglass, heat may build up. Remember, they were designed for open back cabinets.
- RE: F12N in a box - amnesiac 12:15:40 07/02/07 (6)
  Didnt realise it was that big a problem.I think I have seen supravox 15 inch field coils in ported boxes .Perhaps if I was keen I would bolt on a cpu water cooling sink and water coil them.I cool my cpu that way. But I am not. So I will try this one in the JE labs baffle first.Would you know if these vintage jensen replacemnt cones on ebay would fit these drivers? and thanks you have got me a bit more grounded on this project:)
  - ebay jensen cones (Open in New Window)
  - RE: F12N in a box - DHT 4 ME 14:05:10 07/02/07 (5)
    They are a much thicker paper. The A-12/ F-12 cones are very thin. I have replacements that I bought from the same Ebayer for the A-12. If you use the thicker cones you will loose a few db's. The F-12's are very good in an OB. I recommend 2 per side minimum. 15 -25 watts should do well.
    
    Bob
    - RE: F12N in a box - amnesiac 21:52:42 07/02/07 (1)
      Hi Dht Could you please elaberate on what advantages 2 per side brings.Are they limited in output? This will be blowing my budget.And all so any guess how the heavier cones may affect performance other then efficiency eg frequency responce. Thank you
      - RE: F12N in a box - DHT 4 ME 22:33:56 07/02/07 (0)
        
        In Reply to: RE: F12N in a box posted by amnesiac on July 02, 2007 at 21:52:42
        
        The bass response falls off fast in an OB so you need the extra output to compensate . I ran 2 and crossed one in at 300hz @ 6db . that worked well in my room. The first tweeter I used was a Sequerra ribbon crossed in at 1600. That was a little too high so I got a Radian 1.4" in a waveguide from Parts Express @ 1k. I would not use a heavier cone as it will screw up everything good in the driver.
    - RE: F12N in a box - nullspace 18:37:10 07/02/07 (2)
      Hi Bob --
      
      I think you said that you've moved on from the Jensen field coils, but could you tell us a bit more about your setup when you had them? You ran two of them in parallel? And what kind of high-freq driver did you use? And where did you cross them at?
      
      Thanks for the help. I have a quad of A12 I'm working with, and am thinking of using Altec 802's on AH 1000hz horns for the top end.
      
      Regards,
      John
      - RE: F12N in a box - DHT 4 ME 22:37:40 07/02/07 (1)
        
        In Reply to: RE: F12N in a box posted by nullspace on July 02, 2007 at 18:37:10
        
        That would work well. Biamp or use an autoformer and you will be amazed at the imaging. I also recommend a sub to lighten the load in the bottom .
        Really nice drivers with a little bit of tweeks. See my past posts on the A-12
        Bob
        
        RE: F12N in a box - nullspace 07:38:46 07/03/07 (0)
        
        In Reply to: RE: F12N in a box posted by DHT 4 ME on July 02, 2007 at 22:37:40
        
        Thanks Bob. I do have a pair of 21" woofers suitable for OB that will be doing <100hz.
        
        Regards,
        John

Post a Followup:

FAQ

Post a Message!

Forgot Password?

Moniker (Username):
Password (Optional):
	Remember my Moniker & Password (What's this?) Eat Me
E-Mail (Optional):
Subject:

Message:	(Posts are subject to Content Rules)

Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:	Automagically notify you when someone responds.

To view your new posting or follow-up, click on the RELOAD or REFRESH button on your browser.

This post is made possible by the generous support of people like you and our sponsors: