PDA

View Full Version : n2400 crossover



thymanst
05-30-2009, 06:19 AM
I have a question about the n2400 crossover - from what I've seen there is 16 ohm and a 8 ohm versions = from what I've read, the d130's are all 8 ohm... so is the 16 ohm n2400 really 16 ohm? - I'm trying to put together a pair of these to build d130/075 speakers this summer - I thought I had bought a pair in Canada, but the guy never shipped them and kept my money (Ross Mcknight AKA sam r i or fatonesam) paypal recovered a whole $2 from him - anyway if any leads on n2400 pls let me know (the d130's are 8ohm Signatures)

BMWCCA
05-30-2009, 07:27 AM
I have a question about the n2400 crossover - from what I've seen there is 16 ohm and a 8 ohm versions = from what I've read, the d130's are all 8 ohm... so is the 16 ohm n2400 really 16 ohm?
My D130s are labeled 16-ohm and use N2400s. There's been much discussion here about the actual impedance of the D130. I believe Harvey may have said they were all the same, regardless of label. If you check the brochures in the library, up to around 1966 the D130 and the N2400 were rated 16-ohm. From about 1969-on both were rated 8-ohm. I assume they are the same, regardless of label. :dont-know

Beowulf57
05-30-2009, 07:42 AM
This should not be an issue...AFAIK JBL changed the nominal impedance ratings on drivers such as the D130 from 16 ohm to 8 ohm, however the actual impedance remained the same, unless you are talking about early models which where rated at 32 ohms. Here is the N2400 schematic if it may be of use to you: note that the test setup used an 8 ohm load for standardization.

thymanst
05-30-2009, 02:39 PM
The best I can find right now is a one 8 ohm and one 16 ohm crossover - It look like there are some inexpensive JBL crossover with L-pads (crossed at 2.5 khz) that I could buy to hold me over until originals show up - I might even go the parts express route and make my own (would be first time doing a crossover) - I was looking at the c34 plans in the library ....

fecooper
06-01-2009, 12:39 PM
Baron030 did an excellent thread on the The N2400 Revealed. He basically refurbished an old N2400 crossover. I followed his lead and procured two used N2400 cerossovers on e-bay and refurbished them with new capacitors from Parts Express. By the time I was finished, it cost no more than if I had bought all new parts from Parts Express, plus I had the extra-plus of having a JBL crossover that matched my JBL speakers. My advice - by the time you buy a circuit board, terminal connectors, faders, capacitors, inductors - it's much nicer and easier to just get some used N2400 crossovers and replace the capacitors.

Baron030
06-01-2009, 04:04 PM
If you are going to build all new N2400 networks from scratch, then consider updating the original design to include charge coupling and bypass caps as well. Here is a revised schematic:

Baron030:)

fecooper
06-03-2009, 03:05 PM
Do you think the bypass capacitors on the LF really make that much of a difference? JBL never seemed to think the D130 speakers needed a bypass capacitor.

Baron030
06-03-2009, 04:16 PM
Hi fecoopr

You are probably right about not making a lot of difference in bypassing the LF part of the network.
But, it is not without precedence in JBL history.
Here is a link to a Bypass Cap thread:
http://audioheritage.org/vbulletin/showthread.php?t=3555 (http://audioheritage.org/vbulletin/showthread.php?t=3555)

Notice that the second generation N110A network as used in the JBL Model L110A 10-inch 3-way bookshelf loudspeaker system has a bypass cap for its woofer.

So, that is why I included bypass caps on the low pass part of the revised N2400 schematic. Now, if it was me building this circuit, then I would use cheap Dayton Film and Foil Polypropylene bypass caps for the D130 and then use the savings for some more expensive bypass caps for the 075. (Audio Cap Theta Poly Film, for example)

Now, there is one thing that will really improve sound of the D130 when used with a stock N2400 network. And that is replacing the small 20ga iron core coil with something better. Either a larger iron-core coil or better still a heavy gauge air-core coil. :yes:

Baron030 :)

ngccglp
11-02-2014, 02:37 AM
Hi,

sorry to have to revive this thread. May I know if I can use this schematic if my woofer is 8 ohms and my 2402 is 8 ohms?

thanks.

Baron030
11-02-2014, 08:27 AM
Yes, the N2400 network with a 1.0 mH coil is designed for a 8 ohm woofer (D130) and a 8 ohm bullet tweeter (075 = 2402). :yes:

ngccglp
11-15-2014, 04:51 PM
Thank you Baron.

Bumba
01-28-2020, 08:29 AM
Yes, the N2400 network with a 1.0 mH coil is designed for a 8 ohm woofer (D130) and a 8 ohm bullet tweeter (075 = 2402). :yes:
Hi Baron,
I recently got a pair of speakers with d130, n2400, 075 (diaphragms need to be replaced) from an estate sale. Theyíre all labeled 16 ohm.



Will it work if I use 8 ohm diaphragm and rebuild n2400 as you did in The N2400 Revealed?
​if not, I would use 16 ohm diaphragm and new caps but am not surewhat caps to replace the existing caps? The label on the caps didnít have part numbers.


I donít know much about speakers, but love to make these sing again. Thanks for your help and suggestions.

Baron030
01-28-2020, 10:39 AM
Hi
In the 030 system, the crossover network is rather simple and historically the main differences between the 16 ohm and 8 ohm versions has been the inductance value of the coil feeding the D130 driver. Which is why in some of the early 030 systems, JBL used the N2600 crossover. If I understand your question right, your D130 drivers have 16 ohm voice coils and you want to replace the 075 diaphragms with new 8 ohms diaphragms. Actually, you do not need to modify your crossover networks when making a change to the impedance of the 075 drivers. But, I suspect that the L-Pads will need to be replaced. As in they are very noisy and they cut in and out during adjustments. And I see that your crossovers do not have the 5 ohm, 11 watt resistors. Which were added to newer versions of the N2400 network to prevent people from over driving their 075 drivers by turning the L-Pads all the way up to 11. The two 5 ohm, 11 watt resistors form a fixed -8.4 db L-Pad before the variable L-Pad. These resistors are optional. But if you are going to spend the money for new diaphragms, then add spend a few extra bucks for the 5 ohm resistors, in a 10-12 watt range. Itís cheap insurance for the new diaphragms.


If you are thinking of a complete re-build of the crossover networks and you have 16 ohm D130 drivers, then the coil value is most likely 1.4 mH and all the capacitor values remain the same as the 8 ohm version of the N2400 network.


Baron030:)

script56
01-28-2020, 06:32 PM
If jbl speakers were really all 8 ohm despite label? Why would collectors demand the more expensive 16ohm version? And what tap do you use on amps for jbl speakers, 8 or 16 on amp?

Bumba
01-29-2020, 01:45 PM
So, the attached schematic would be correct for my case? Thanks.

Baron030
01-30-2020, 07:15 AM
Hi Bumba

I did a little looking around and it appears that 1.4 mH is not a stock off the shelf size. Which means that if you were to replace your existing JBL coils, you most likely need to order a larger 1.5 mH coil and then remove winding to bring the inductance down to 1.4 mH. To be honest, I am only guessing that your existing JBL coils has an inductance of 1.4 mH. If you plan on replacing the JBL coils with something else than you will need an inductance meter and would need to measure your coils. And order replacement coils according to the actual measured value. And keeping the DC resistance of the replace coil a low as possible (under 0.5 ohms).

If it was me, I would not replace the JBL coils and just replace the L-Pads and Caps and add the 5 ohm resistors.

Baron030:)

Bumba
01-31-2020, 12:00 AM
Hello Baron,

I noticed the missing 1.4mH while searching online too :confused:. Will keep the JBL coils, order other parts and work on it. Thanks for your helps and suggestions.

bumba