driver advice for 2360 horns on Altec A7/828s

[JeffW]

If you go with an active crossover, diaphragm impedance isn't as big of an issue as it is with passive crossovers.

There are guys on here who prefer the coated diaphragms to Be diaphragms if used in a 2 way, if going 3 way where absolute top end extension isn't needed, then Be has a little smoother response.

[Earl K]

<<<<SNIP>>>>I still want a traditional 800Hz xover for immediate future. Looking at a pair of JBL LX13 16 Ohm xovers- do you know if these would be decent, compatible?

The LX13 is the consumer equivalent to the JBL-PRO 3110 network .

There are a couple of pairs currently for sale ( on that auction site ). The lowest priced pair is pretty attractive .

That said, they're barely worth that cost when compared to modern replacement parts.

- ( With the LX13/3110 ) some sort of crossing-over action will certainly happen > though the results will hardly be optimal since your custom setup will need a network designed explicitly for it .

If purchased, the Zobel circuit in the woofer section should be tweaked to work with you Altec woofers ( so-called 16 ohm JBL woofers from that era were still lower in real impedance than their Altec counterparts, more like @ 12 vs 16 ohms > & that's reflected in the LX13's Zobels value using a 10R resistor ).

You might also need to add a bit of capacitance to actually achieve even the stated 800hz target .

One attraction of these networks is of course their inclusion of autoformers.

Attenuating your horn circuit by the max ( 10db ) and then restoring the HF via a bypass capacitor ( a la the 3110A network ) will offer some much needed midrange EQ to HF rebalancing .

[kip.duff]

If you go with an active crossover, diaphragm impedance isn't as big of an issue as it is with passive crossovers.

There are guys on here who prefer the coated diaphragms to Be diaphragms if used in a 2 way, if going 3 way where absolute top end extension isn't needed, then Be has a little smoother response.

This is important info. Let me see if I have it right. (No intent to spark controversy here )

2-way: Aquaplas may be on par with Be and good choice. To me this implies that some believe Aquaplas does the top end better, so overall, performs well between 800 Hz to top.
3-way (at this point, I have no intentions of 3-way): Be does midrange best in both 2-way and 3-way- but does not do very top end quite as well as Aquaplas.

Thanks so much for your input......

[kip.duff]

The LX13 is the consumer equivalent to the JBL-PRO 3110 network .

There are a couple of pairs currently for sale ( on that auction site ). The lowest priced pair is pretty attractive .

That said, they're barely worth that cost when compared to modern replacement parts.

- ( With the LX13/3110 ) some sort of crossing-over action will certainly happen > though the results will hardly be optimal since your custom setup will need a network designed explicitly for it .

If purchased, the Zobel circuit in the woofer section should be tweaked to work with you Altec woofers ( so-called 16 ohm JBL woofers from that era were still lower in real impedance than their Altec counterparts, more like @ 12 vs 16 ohms > & that's reflected in the LX13's Zobels value using a 10R resistor ).

You might also need to add a bit of capacitance to actually achieve even the stated 800hz target .

One attraction of these networks is of course their inclusion of autoformers.

Attenuating your horn circuit by the max ( 10db ) and then restoring the HF via a bypass capacitor ( a la the 3110A network ) will offer some much needed midrange EQ to HF rebalancing .

"That said, they're barely worth that cost when compared to modern replacement parts". Can you clarify?


One attraction of these networks is of course their inclusion of autoformers." Briefly, what in an "autoformer"?

I am considering both LX13 and 3110As. In the case of the LX13, there is no indication anywhere on them (and in JBL specs I found online) as to what the nominal impedance is. Nor do the vendors seem to know. In the first doc you posted, it states that the Z is 16 for the 3110A. So, are both LX13 and 3110A 16 Ohms Z?

OK- on further research and info from a vendor, 3110 is 16 ohm and 3110A is 8 ohm. At this point, I believe LX13 is 8 Ohm.

Thanks......

[Earl K]

Briefly, an autoformer is a tapped inductor ( coil ) .
- Within a crossover, it combines the function of an inductor with the possibility of voltage loss ( attenuation ) through the various taps ( iow; this attenuation is usually performed by resistors ).
- Some ( those who claim to be able to hear the sound of resistors ) sometimes prefer it's ( autoformer ) "sound" .

The LX13 = an 3110 ( according to JBL's schematics ), therefore the implication is that it too is meant to be used with the older ( so called 16 ohm ) drivers .



PS; Go to Parts Express; Cross-over Parts to figure out the relative worth of pre-made crossovers .

[macsic]

Whoa. Thanks to you and sguttag, I've been starting to scratch the surface of the DSP thing. A small door opening to a room with 100 doors kinda thing. Just been looking at MiniDSP products- WTF. How can I buy something that's inexpensive and small? Brings to mind my Sonos Play 5 iPhone streamer- which I am very impressed with. These products are something I'm gonna get involved with- but for now, may probably get conventional crossover box just to get into a 800Hz setup.

Are your horns the Tony Kahn replicas?
And you're not using the 2328 throats?
Does your XTA have RCA connectivity?

MiniDSP was in my list but I had luck to buy the XTA at a good price.
Yeh! they are a perfect replica but I don't have the name of the guy who made it.
Yes a JBL 2328 throats.
XTA have only XLR connections.

[kip.duff]

After seeing the mixed and confusing info on LX13 impedance specs, I thought: 1200 Hz is also an option, so I'll look for JBL N1200 on eBay. Again- all over the map on whether 8 or 16 Ohm. I found JBL "instructions" which clearly showed them at 8 Ohms- also, a diagram stating same . Early versions actually are branded on the front as 16 Ohms. Several on eBay are representing newer ones as 16 Ohm. There are some very nice 80s looking clean sets at good price just a few miles from me on eBay. One seller said the speaker cabinets he removed them from were original JBLs and they were driving JBL woofers labeled as 16 Ohms. It's as though N1200s and LX13s were a "line" of crossover that came in different variations and versions. Amazing lack of specificity here.

Based on Earl K's point that JBL woofers had lower real world Z than the Altec/GPAs 416/515 types, maybe I'll stop looking at used JBLs crossovers for now- barking up the wrong tree. Thanks Earl! I am going to complete reading of the links you sent now. Also considering 1200 Hz crossovers from GPA- I think he can configure in 16 Ohm- and obviously is familiar with 416 and 515 series woofers. Also, I can look at used Altec crossovers- which I haven't done yet.

Just to be clear- I'm not looking for ultimate, final crossover at this point. Just want to get going with any acceptable 800 to 1200 Hz crossover to try out in place of my repaired original 1966 Altec 500 Hz crossovers. Plenty of time to educate myself on fine points of a "dream" crossover and carefully plan an educated build later.