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Scooter
03-17-2005, 03:56 AM
I have been giving some thought as to how to proceed with the network that I am going to use with my L110s, and I decided on an "upgraded" N110A. Tentative plans call for Mundorf caps (not the Silvers--yet), 14 gauge air core inductors, and Eagle resistors. I have been advised to avoid low DCR inductors in the shunt portions of the mid and high sections of the x-over, as this will alter the circuits Q to a degree that can cause harshness in the tweeter. True? Is it better to stay with the original values in this section? Input appreciated.

Scott

4313B
03-17-2005, 04:19 AM
N110A


I have been advised to avoid low DCR inductors in the shunt portions of the mid and high sections of the x-over, as this will alter the circuits Q to a degree that can cause harshness in the tweeter. True? Is it better to stay with the original values in this section? Input appreciated.Actually it is mandatory that you maintain the original DCR values of these special inductors.

The DCR of L3 is ~ 7.5 ohms. L3 is actually an LR conjugate filter that reduces the effects of the LE5/subenclosure resonance characteristics.

The DCR of L4 is ~ 7.5 ohms. L4 (as part of the LCR conjugate circuit) reduces the effects of the resonance characteristics of the 066.

4313B
03-17-2005, 04:34 AM
Impedance plots of LE5-9 in "standard" subenclosure with and without conjugate filters.

4313B
03-17-2005, 04:40 AM
For those who might be interested -
The N110A network can be used in the 4313B system as is.
The N110A network can be used in the L96 system as long as the value of C5 is changed from 18 uF to 14 uF.
Some might like to explore the differences between the various networks, how they impact the performances of the systems.

Scooter
03-18-2005, 01:28 AM
Thanks much Giskard. Glad I asked.

Do you know the wire gauge of the inductors mentioned? I have the N110, but not sure if the A version is the same. I need this info to get a cost estimate from Madisound.

Gratefully,

Scott

4313B
03-18-2005, 02:30 AM
No, I don't know the gauge off hand, I'd have to go measure them.
I have quite a few of the 3.5 mH somewhere but very few of the 1.0 mH.
Here's the N110 schematic for comparison.

Scooter
03-19-2005, 02:22 AM
I took a look at the coils corresponding to L3 and L4 on the N110 network, and the wire size is very small, which I now know one would expect with a relatively high resistance like this. L4 I would guess to be 24 ga. and L3 22 ga. However, Madisound says that they can wind as small as 26 ga., but that this will not be adequate for 7.5 ohms. So much for my guesses, I guess. Looks like the best course is to send them the N110s for salvage, and hope the coils are usable.

Out of curiosity, if you were starting from scratch on the N110A crossover, and you did not have spare coils, or a way to obtain the winding of such small size for the 7.5 ohm requirement, what would you do for an improvise?

Love those graphs! Thanks.

Scott

4313B
03-19-2005, 05:05 AM
Out of curiosity, if you were starting from scratch on the N110A crossover, and you did not have spare coils, or a way to obtain the winding of such small size for the 7.5 ohm requirement, what would you do for an improvise?I would use the smallest air core I could find and put a series resistor with it to get the required DCR (Solen Perfect Lay 20 AWG comes to mind). JBL did just that in later system designs.

DavidF
03-19-2005, 10:27 AM
Out of curiosity, if you were starting from scratch on the N110A crossover, and you did not have spare coils, or a way to obtain the winding of such small size for the 7.5 ohm requirement, what would you do for an improvise?

Scott

Giskard suggestion is right on track. This gets you the same result as with the small-wire coil. You should not consider this a compromise. The reason to use the small wire winding is to combine the resistance and inductance in one piece for cost saving consideration.

DavidF

Scooter
03-20-2005, 01:17 AM
The person at Madisound that I am consulting with thought that a series resistor might do it, but he seemed to dismiss this, as he felt the resistance should come from the coil itself. I will tell him to read this thread. Great advice as usual--and VERY much appreciated.

Scott

Scooter
03-21-2005, 12:13 AM
Some further exchange on this subject has made me aware that when considering using a series resistor with e.g., a 20 ga. coil, that it is not just DCR, but AC impedance too, and that they do not react quite the same. Does someone have some insight on this? It was also pointed out that we do not know the actual values of the coils without measuring them (referring to my N110 network). So I think it best that I send them the networks for testing-- and some certainty. Scott

4313B
03-21-2005, 07:04 AM
Does someone have some insight on this?Perhaps...

4313B
03-21-2005, 07:05 AM
Ok.
I took time out of my day to run this.

Load is JBL Model LE5-12 in free air (Don't compare it to the graph above. I didn't feel like digging out a subenclosure today. The LE5-12 was just laying on the bench.)
1st run is ubiquitous JBL 3.5 mH inductor with 7.5 ohms DCR.
2nd run is JBL 3.5 mH inductor with 1.1 ohm DCR in series with a JBL 6.2 ohm resistor.


So I think it best that I send them the networks for testing-- and some certainty.I think it's best you build the damn things yourself dude. http://audioheritage.csdco.com/vbulletin/images/smilies/wink.gif

Scooter
03-22-2005, 03:39 AM
Giskard, you are truly a human Encylopedia 'O JBL!! You have my gratitude once more. Building the crossovers myself is my goal on the subsequent JBL project, whatever that may be. Still pillaging knowledge at this point.

It feels like I have gotten myself in the middle of some disparity as to how to best proceed with this network... but some things are self-evident. Not a good place to be...people can get annoyed and pissed-off at you...makes for a "dividing" network.

Scott