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hhibrownsbacker
12-02-2008, 05:26 PM
Im not to good at repairs but figured I could handle this one, maybe i was wrong:banghead: but I have had a set of mid 1950s C36s(D131 and 075 and N2600 crossover) for awhile now and have tried them with so many amps its not funny, everything from tubes to SS and the same results with both. Dont get me wrong they sound good BUT Im sure they could sound allot better. First off the highs are so high they are shrilling(appropriate word) and the Bass is lacking. The only time I really do enjoy them is with the bass turned up all the way on any amp and the tweeters almost shut down thru the crossover. SO I was gonna start with recapping the crossovers and see if that didnt help(they are over 50 years old so it cant hurt) and if that didnt help I was gonna have the woofers reconed and see if that helped. Well Im into the crossovers and I could use some advise on what the heck these grey boxes are. Ive never seen anything like them in any crossover Ive ever looked at, but then again Ive never opened up a crossover that was over 50 years old. Any help would be appreciated and thanks in advance.

Baron030
12-02-2008, 05:59 PM
Hi hhibrownsbacker

I see that this is your first posting. So, welcome to the Lansing Heritage site.
Here is a link that will get you a schematic of your network:

http://www.jblproservice.com/pdf/Network%20Schematics/N2600.pdf (http://www.jblproservice.com/pdf/Network%20Schematics/N2600.pdf)

The boxes are most likely the capacitors in the network and if you see what looks like a small transformer then that is the coil.
New capacitors and an L-pad can be ordered from www.partsexpress.com (http://www.partsexpress.com/)

But, before you overhaul it, please take the time to document with more pictures as to what you have got there.
Itís not every day that people get to look inside one of these old networks.

Baron030:)

hhibrownsbacker
12-02-2008, 06:33 PM
Thanks for the welcome, heres the pics you requested of the network, I really cant get a different angle other than straight in, hope it helps. Im just gonna put it back together for now, i think its over my head and i should probably just get another set of crossovers to screw up rather than this particular set. i though it was gonna be a easy clip and solder, and now Im not sure it will even address my concerns. Im gonna try a sub and see if together I cant get what I want. Im sort of stuck right now as far as what to do so rather than do anything I should probably do nothing

BMWCCA
12-02-2008, 06:47 PM
Nice project but don't expect too much out of the D131. The lack of bass may be more what you're used to than a defect. An 075 can be shrill if you hit it just right, plus they're really designed to be crossed around 7000 Hz as UHF elements. I'm curious to see how your crossovers work out since I have some equally as old in daily use. But mine should be even easier since they're N2400s.

Just for kicks, have you tried running the D131 full-range without the 075 or the crossover in the system just to check it? Sounds like you might even prefer it that way.




Well, I see now you've got Zilch's attention over at Audiokarma. As always, good advice and cut right to the chase.

Baron030
12-02-2008, 08:36 PM
Hi hhibrownsbacker

I forgot to tell you that if the L-Pad needs replacing then the most direct replacement has a 15 watt power rating.

Baron030:)

jkolze
11-27-2010, 09:08 PM
Hello,

I have a 2600 with caps just like the one in the prior posting with pictures. The same numbers on the caps. Both sets of caps read (2) 16 mfd's, this doesn't compare well to the 3 mfd in the schematic. I have to wonder what's going on as it seems odd that all the caps would drift off so much. I'm sure they are orginal. I measure a new cap with my Fluke at it's correct, so it's not the meter. Has anyone else seen this?

jkolze
12-03-2010, 08:18 AM
Just in case anyone is looking at this, I figured out that my the caps are 3 mfd. I think they have enough parasitic resistance that it through my cap meter off. I hooked them up in an R/C circuit and they act like 3 mfd caps.

Looking at the crossover, I find it odd that the tweeter is a first order network and the woofer is a second order network. Also looking at the schematic on the internet (Link below), the woofer connection 1 is not connected to the circuit, it really should be connected to the mid point on the switch. Also note that the switch is in the 16 ohm positions in both the HF and the LF.

When the switch is in 16 ohms, the values are 6 mfd and .7 mh. With a 10 ohm driver the cross over frequency would be 2.5k in a first order, and how the shunt cap would affect the crossover point Iím not sure. Does anyone have the software to graph what this would look like?

Here is the Link: http://www.jblproservice.com/pdf/Network%20Schematics/N2600.pdf