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stimpiew
07-13-2003, 05:29 AM
Hi, I've got a question: In the 3114 network there is the 0.16mh inductor parallel in the 077 network. In the text on the .pdf file it says 0.16mh or "-3dB resistor". What do they mean by this? Since I can't get my hands on this 3 wire 0.16mH inductor, how could I solve this best?
Simply 0.08 in parallel and a -3dB resistor or 0.08 series/0.08 parallel. Or 0.16mH in parallel and -3dB,..?
I was thinking an inductor in series with a tweeter can never be good?
Thanks,
Wim

4313B
07-13-2003, 07:55 AM
-3 dB means the tapped autotransformer is tapped at that attenuation position. If you can't use, don't want to use, or can't find, the 0.16mH tapped autotransformer then use something like a 0.05mH series inductor followed by a 0.11 parallel inductor.

In my 4315B Studio Monitors I added an additional -3 dB resistor pad on the 2405 (077).

Do you need schematics?

"I was thinking an inductor in series with a tweeter can never be good?"

There are plenty of decent systems that have chokes in series with the tweeters, one example that comes to mind is the L250 loudspeaker. Of course Greg did skirt the need with the 250Ti design :D

stimpiew
07-13-2003, 11:34 AM
No thanks, I've got the schematics,
thanks for your help, I'll give it a try,
Wim

boputnam
07-18-2003, 03:34 PM
Giskard....


Do you need schematics? If the offer still stands, I have a project using the L65 network which would benefit from having a schematic. Possible?

boputnam
09-04-2003, 09:46 PM
Ugh! Here we go...

Conditions of my homebuild using the N65:

HF - 075
MF - LE5-9
LF - LE14A

These are all negative transducers.

Using the Cricket polarity tester, the N65, wired-up "factory", in cabinet, with the above transducer assemblage yielded:

HF (+)
MF (+)
LF (+)

But, my read of the network suggests that, at the transducers the polarity should be:

HF (-)
MF (+)
LF (+) - unless the 126A is "positive", like the 123A, then this would be (-). Anybody got one to test? Please?

I'm as confused on the 075 as I am on the 126A. Test of the 075 out-of cabinet confirms it is negative. Why it yields (+) in factory wiring (red to Red) is bothersome, to say the least...

Ideas?

NB: Addendum - review of the N65A and N65B reveal the LF's run "reversed" compared to the N65, so there was shift in LF polarity mid-L65's...

boputnam
09-08-2003, 10:57 AM
From contributions to another Thread (N65 Duct Tube - Link (http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=727)) we have verified the 126A LF is POSITIVE transducer (i.e. L65 network), opposite of JBL convention.

Later versions of the L65 - the L65A and L65B - use LF's of JBL conventional (negative) polarity.

Here is the "L65 Variants" with fine print regarding the 126A, for posterity sake.

Now, everyone back to your cabinet phasing... ;)

4313B
09-08-2003, 11:55 AM
Originally posted by boputnam
Giskard....

If the offer still stands, I have a project using the L65 network which would benefit from having a schematic. Possible?

I see you already have the schematics that I posted in another thread :)
Did you get the LX30 schematic as well?

http://www.audioheritage.org/vbulletin/showthread.php?s=&postid=705&highlight=lx30#post705

http://www.audioheritage.org/vbulletin/showthread.php?s=&threadid=222&highlight=lx30

boputnam
09-08-2003, 12:16 PM
Originally posted by Giskard
Did you get the LX30 schematic as well? Yes thanks, friend. :thmbsup:

And, I've wondered if they would've been a bit better pick for my little format ;) cabinet project. But, the L65 fit SO nicely into the cabinet, with them cute little binding posts going right out the rear cut-out.

Maybe yes, maybe no...?

But, eBay was so forthcoming with the L65's...

4313B
09-08-2003, 12:29 PM
"Maybe yes, maybe no...? "

If the N65 doesn't cut it then move on to the N65A or N65B. If those don't cut it and another pair of LX30's show up then maybe they would be worth a try (a pair were on eBay recently). I just thought it would be interesting to everyone to know that the LX30 was out there and that it was used in the LCS version of the L65 (known as the S21).

http://www.lansingheritage.org/images/jbl/catalogs/1976-comp/page7.jpg

http://www.lansingheritage.org/images/jbl/catalogs/1979-comp/page06.jpg

http://www.lansingheritage.org/images/jbl/catalogs/1979-comp/page08.jpg