driver advice for 2360 horns on Altec A7/828s

[kip.duff]

I've decided that I would like to try JBL 2360 horns on my Altec Voice of the Theater A7/828 speakers. I've picked up a few basics in these threads: crossover around 700Hz and TAD 4002 is the best HF driver. I'm not against buying a used set of 4002s- just not yet. I see there are some decent looking 2446Js available very affordable and I am on the brink of buying a pair. JBL lists 2446, 2450, and 2485 as the drivers for these horns.

Until I decide to get the TADs, is the 2446J a decent approximate 2nd best for the 2360 horns? Diaphragm changes helping?

Does the TAD 4002 bolt up to the 2360 throat?

My A7/VOTTs have GPA 416-16B Alnico LF drivers, Emilar EH800 horns on Altec 802D HF drivers, 16 Ohm. Original N-500-E Xovers rebuilt with Russian capacitors. They are driven by Bottlehead 8w 300B SET monobloc amps. My A7s seem heavy on the high end- I have the Xover attenuation knobs on max, -6dB. I don't know why this is- would prefer to have a system that does not HF need attenuation. I figure, at minimum, I will have to get Altec or GPA 515B Alnco LF drivers to try to match the SPL of the JBL 2360/2446Js. Also will need to make a new Xover at 700Hz.

I apologize for fact that this topic has been touched upon in various threads- I have been looking thru them for a couple of days and they have become a bit of a blur. I am hoping the accelerate the decision process by asking this question fresh to people who are WAY ahead of me in knowledge on this stuff.

Thanks, Kip......

[sguttag]

The 2446 (or 2450) are a good match to the 2360 horn. The response is smooth and very predictable. I've only used or worked with about 500 or so of them as they were very popular in movie theatres since the early 80s (noting that the driver in the early 80s would have been the 2445 before the 2446 came out and some VERY early 2360/24xx drivers would have been earlier forms of the 2400 series but the first one I worked with was the 2445/2360).

In cinema, we crossover at 500Hz to keep dialog out of the crossover region. The 2360/2446 will have no problem going down that low. Note too, unless you plan to have the horn be proud to the LF cabinet, you will likely need to introduce some form of time-delay on the LF section to get time-alignment at crossover.

My personal recommendation for a large-horn A5 (because if you are considering a 515 and a large format horn...it isn't an A7 anymore) is the MR94 with a 288G-L (I like the Tangerine phase plug). The 299 is also a good HF driver (same as the 288...just differs in the aluminum versus Pascalite diaphragm). To my ears, it just sounds better.

As for Bill's LF drivers, I REALLY like the 515-LF. I know you are indicating a like for Alnico drivers but this driver seems to be just incredibly smooth and better responding than other 515 incarnations and I think I've used them all, at some point (definitely, I've used or worked with the 515B a lot). The last time I got the 515-8LF, Bill made them with vents on the dust dome so it has the proper "look" though it is normally issued with a rear-vent.

[macsic]

I've decided that I would like to try JBL 2360 horns on my Altec Voice of the Theater A7/828 speakers. I've picked up a few basics in these threads: crossover around 700Hz and TAD 4002 is the best HF driver. I'm not against buying a used set of 4002s- just not yet. I see there are some decent looking 2446Js available very affordable and I am on the brink of buying a pair. JBL lists 2446, 2450, and 2485 as the drivers for these horns.

Until I decide to get the TADs, is the 2446J a decent approximate 2nd best for the 2360 horns? Diaphragm changes helping?

Does the TAD 4002 bolt up to the 2360 throat?

My A7/VOTTs have GPA 416-16B Alnico LF drivers, Emilar EH800 horns on Altec 802D HF drivers, 16 Ohm. Original N-500-E Xovers rebuilt with Russian capacitors. They are driven by Bottlehead 8w 300B SET monobloc amps. My A7s seem heavy on the high end- I have the Xover attenuation knobs on max, -6dB. I don't know why this is- would prefer to have a system that does not HF need attenuation. I figure, at minimum, I will have to get Altec or GPA 515B Alnco LF drivers to try to match the SPL of the JBL 2360/2446Js. Also will need to make a new Xover at 700Hz.

I apologize for fact that this topic has been touched upon in various threads- I have been looking thru them for a couple of days and they have become a bit of a blur. I am hoping the accelerate the decision process by asking this question fresh to people who are WAY ahead of me in knowledge on this stuff.

Thanks, Kip......

Hello,
I also have VOTT with 416, I tried 515-16G and I prefer 416 for my home use, you have to consider this because there are often good products but used in the wrong places. Ah yes I doubled the VOTT to increase because the 2450 are really effective and applied a - 5db gain on 2450 to balance everything, I'm still besides tinkering with these parameters now. I have had several drivers for different horns over the years and what I prefer among what I have tried are 2450 with 2397, I have tried 2360 with different drivers like 2440, 2441, 2450 and I kept the 2450, take note that the 2450 are IMHO better if the diaphragms used are the aquaplased because the Ti Ribbed are definitely worse and they would never have replaced the 2441. Let's go back to the 2360 that I had also, these are big horns that were designed for large listening rooms and once again for my use these give me a less good image than the 2397 which are what I have preferred so far. A friend who also had 2360s replaced them with 2395s yet the 2360s have an excellent reputation, I think that the listening room has a lot to do with it because the 2360 projects much more forward then you have to have a large room for the image to build.
I have no experience with TAD but with what I currently have I really don't need it maybe until I listen to it :-)
With time and experience we sometimes realize that where they are used is very important.
P.S. Thanks Google translate.

[macsic]

sorry for the duplicate

[kip.duff]

Thanks guys. I'm gonna research your answers and reply.

[kip.duff]

Hello,
take note that the 2450 are IMHO better if the diaphragms used are the aquaplased because the Ti Ribbed are definitely worse and they would never have replaced the 2441.

"Aquaplased": I've done some searches, I'm not seeing a supplier. Are these original JBL or aftermarket?

[Mr. Widget]

"Aquaplased": I've done some searches, I'm not seeing a supplier. Are these original JBL or aftermarket?Others can pop in with the particular model numbers, but most of the JBL 4" diaphragms are interchangeable. Some of JBL's drivers came with a 4" titanium diaphragm that was coated with a damping compound called aquaplas by JBL. They use this coating on a number of woofers as well.


Widget

[kip.duff]

Others can pop in with the particular model numbers, but most of the JBL 4" diaphragms are interchangeable. Some of JBL's drivers came with a 4" titanium diaphragm that was coated with a damping compound called aquaplas by JBL. They use this coating on a number of woofers as well.


Widget

So these are JBL parts. I can research that. At this point, I'm steering towards 2450- and when I get one it may already have those- or I can install some.

This Aquaplas thing sounds important- my concern with the original 511B horns on my A7s was aggressiveness and glare- were harsh sometimes.

[macsic]

So these are JBL parts. I can research that. At this point, I'm steering towards 2450- and when I get one it may already have those- or I can install some.

This Aquaplas thing sounds important- my concern with the original 511B horns on my A7s was aggressiveness and glare- were harsh sometimes.

I got these diaphragms in 2451.

https://nsa40.casimages.com/img/2019/12/20/191220035706227919.jpg (https://www.casimages.com/i/191220035706227919.jpg.html)

I interchanged the diaphragms of the 2451 which are 1.5 inch but the motor is the same, with those of the 2450 which originally had Ti Ribbed.

https://nsa40.casimages.com/img/2019/12/20/19122003565742911.jpg (https://www.casimages.com/i/19122003565742911.jpg.html)

I have not tried it but I doubt if you compare 2446 and 2450 using the same diaphragms that you will notice a difference. If you have the money there is another option the Be diaphragms which are unanimous.
So, yes the diaphragm is really important.

[Mr. Widget]

This Aquaplas thing sounds important- my concern with the original 511B horns on my A7s was aggressiveness and glare- were harsh sometimes.Aquaplas helps, but the horn, crossover frequency and type, and how hard you drive it will also contribute to the harshness you mention.


Widget

[kip.duff]

So, at this point, I'm eBaying for 2446Js- I prefer the terminal connection style. There's a pair in FL, but description is vague. Will get Aquaplas after I get the drivers. Chances seem slim that they will come with Aquaplas.

For now, looking for the 2397 horns: more practical way to get started. Still believe I will get some 2360s, but my space is limited. Where there's a will, there's a way- even though the 2360s will be a tough fit in my room:) These would probably have to be local considering shipping- but at least I'm in SoCal where there's probably a few of these floating around.

[kip.duff]

I got some very nice (as new) 2446s with close serial numbers off eBay for $260 + $50 shipping for the pair. Will be trying the original Ti diaphragms for now, but am going to get at minimum the Aquaplas- or possible the Truextent Be frams ($1500?) I'm looking at both 2397s and 2360s on eBay- and I had a question about 2360s.

So far, I have not got much/any info on different versions of 2360. I am close to buying some that are the split type, which I think is later version. Two questions: 1) of the different versions of the 2360, are some considered significantly better? 2) Does the split make it easier to ship (they are in US but far from me)?

I also need to revisit the issue some brought up about my desire to increase output of the A7 boxes to come closer to the SPL of the horns. It seems you believe the 515B, though more efficient, would not be a satisfactory or synergistic way to bring Dbs up in my A7s to be on par with the horns. I thought the 515B was designed for A7 boxes.

Thanks, Kip.....

[kip.duff]

As for Bill's LF drivers, I REALLY like the 515-LF. I know you are indicating a like for Alnico drivers but this driver seems to be just incredibly smooth and better responding than other 515 incarnations and I think I've used them all, at some point (definitely, I've used or worked with the 515B a lot). The last time I got the 515-8LF, Bill made them with vents on the dust dome so it has the proper "look" though it is normally issued with a rear-vent.

Squttag: your audio experience sounds amazing- thanks for response.

I have heard others say that GPA have scored with the 515LF. My mention of Alnico is just a vague superstition that they might sound better- not married to the idea. At this point, I am on a JBL 2446J/2360 and 2446J/2397 path for better or worse- I'm not against MR94/288- just on the JBL path for now. As mentioned in original post, I want to up the efficiency of the A7 boxes- currently, they have GPA 416B (Alnico) drivers. There is not direct efficiency specs comparison for for GPA 416B, 515LF, and 515B Classic. The 515B and 515LF both show 102 dB in a 828 cab. All list Gauss: 11,000, 14,750, and 14,750. So, by comparing Gauss, I see that in theory both 515s should be considerably more efficient. My plan was to get some of these 515s for the A7/828s- any problem with that? Macsic also mentioned possible lack of compatibility.

Thanks for your time, Kip......

[sguttag]

What is your need for the extra efficiency? That isn't necessarily the key to good sound. The 515-8G is a more efficient driver than the others but it at the cost of cone mass (take a feel of the 515-G compared to any other 515 driver. The 515-G, while more efficient, isn't as good as the GPA 515-LF, in my opinion, in terms of frequency response and power handling and overall sound. I'd give up the 1dB of efficiency in a heartbeat.

[macsic]

Hi,
I compared the 515-16G with 416-16 and despite several trials and combinations I always preferred the 416-16 but I do not know more for the other versions of the 515, regarding the efficiency I simply doubled the boxes and an adjustment on my DSP XTA and voila.

https://nsa40.casimages.com/img/2020/01/06/200106021747438984.jpg (https://www.casimages.com/i/200106021747438984.jpg.html)

Currently I'm looking for an amp to power the 416 because my PP2A3 lack a little juice for my rockier days. About the 2360 that I also owned for a while, I liked it but I much prefer the 2397 for the listening room that I have, with 2360 you have to be much further to appreciate, which is why they were designed so in a very large listening room the 2360 would be at their best. With the 2397 the image is better and they disappear, I like.
Keep going, you're on a good track.

[kip.duff]

What is your need for the extra efficiency. That isn't necessarily the key to good sound. The 515-8G is a more efficient driver than the others but it at the cost of cone mass (take a feel of the 515-G compared to any other 515 driver. The 515-G, while more efficient, isn't as good as the GPA 515-LF, in my opinion, in terms of frequency response and power handling and overall sound. I'd give up the 1dB of efficiency in a heartbeat.

You are speaking about 515-G which I believe is a circa 1994 Altec Lansing ferrite version in the 515 line. I have not mentioned this model as one of the models I was considering using- but that could change. At this point, it's not clear to me why you brought this model up. The 515 types I'm considering are the GPA 515-LF and GPA 515C. I see now that I had wrong info in my previous post- when I wrote "515B", I meant GPA 515C ("Classic")- my apologies. So, the two LF drivers that came to mind for my A7/828s are GPA 515-LF and GPA 515C.



"need for extra efficiency". About 2 years ago, I got a set of drivers that were originally belonging to some 1966 A7/825s: 416A LFs, N-500-E Xovers, 511B horns, and 802D HF drivers. The Xovers were not working, so I repaired them with some MBGO Russian caps- otherwise original. I bought a pair of 828s to install the components into. The 416As were pretty tore up, and rather than getting them reconned, I bought some 416-16Bs from GPA. The porting is original 828 spec- 205 sq in (I think)- not the more popular 90 sq in. Frequency response curves I generated showed overall same efficiency for the two port configurations- with some difference in the tow, of course.

This setup has always been aggressive in the high end- I believe for more than one reason. And HF attenuation knob on the Xovers almost always at max attenuation position. With the JBL 2446/2360 or JBL 2446/2397 horn setups I am substituting, I believe the SPL gap between LF drivers and HF drivers will even widen. In any event, I would prefer my A7s not to need any attenuation- and I had assumed that's possible. This is based on an uneducated hunch that the horns will sound better without a resistor in series. That's why I want more efficient LF drivers. I already know I'm a dumbass:), and that some (many?) people may believe my hunch is silly.

This has been a long-winded way of asking: do you believe the GPA 515-LF or GPA 515Cs are appropriate drivers for my A7/828s? Other LF drivers I should consider? TAD? Also, FWIW, I've noticed that in original LF driver specs, 416As and 515s types are designated for 825/828 box use.

Thanks.......

[kip.duff]

Hi,
I compared the 515-16G with 416-16 and despite several trials and combinations I always preferred the 416-16 but I do not know more for the other versions of the 515, regarding the efficiency I simply doubled the boxes and an adjustment on my DSP XTA and voila.



Currently I'm looking for an amp to power the 416 because my PP2A3 lack a little juice for my rockier days. About the 2360 that I also owned for a while, I liked it but I much prefer the 2397 for the listening room that I have, with 2360 you have to be much further to appreciate, which is why they were designed so in a very large listening room the 2360 would be at their best. With the 2397 the image is better and they disappear, I like.
Keep going, you're on a good track.

Thanks so much for your response. Really getting at the heart of my situation. I was teetering on the brink of getting some 2360s, but I am a little more hesitant now, considering my small space. I almost got a set of local 2397s yesterday, but they were pretty beat. 2397s will be my priority. I have some 2446s with original Ti frams and will get Aquaplas or Truextent.

I have assumed that because my A7s are efficient, that my 300B SET monoblocs are adequate. I think I'm gonna abandon that theory and get something like ANK Interstage 300B parallel monoblocs. Not sure- I listen sometimes at loud levels.

I am gonna research your mention of DSP XTA and PP2A3. Are the drivers for the 2397s in your photo attenuated?

[macsic]

Thanks so much for your response. Really getting at the heart of my situation. I was teetering on the brink of getting some 2360s, but I am a little more hesitant now, considering my small space. I almost got a set of local 2397s yesterday, but they were pretty beat. 2397s will be my priority. I have some 2446s with original Ti frams and will get Aquaplas or Truextent.

I have assumed that because my A7s are efficient, that my 300B SET monoblocs are adequate. I think I'm gonna abandon that theory and get something like ANK Interstage 300B parallel monoblocs. Not sure- I listen sometimes at loud levels.

I am gonna research your mention of DSP XTA and PP2A3. Are the drivers for the 2397s in your photo attenuated?

Hello,
There are 300B and 300B ... I have different and they sound different and I use them for mid and high now, depending on the style and level of the 300B can do the trick. A Push & Pull 2A3 is also very good for mid, it's all a question of tastes and needs. For the vast majority of the time a PP 2A3 (do not research it is a DIY) is sufficient on the 416 but I am still looking for the perfect wedding amp for these, I will surely try soon McIntosh, or KT88 or 845 as soon as I get them.
On my 825 or 828 I calibrated the port and I also arrived at around 200po².
On my XTA DP448 I applied a -6db on my 2450J / 2397 for the moment and it's ok but the final is not decided since I will surely change amps soon and the gain on these influences this choice. I cut at 800 on the lowpass and 7,200 on the highpass with the 2397, as you know you can cut lower with the 2360.


"I already know I'm a dumbass, and that some (many?) People may believe my hunch is silly."
If you are crazy then you are not the only one ;-)

[sguttag]

You are speaking about 515-G which I believe is a circa 1994 Altec Lansing ferrite version in the 515 line. I have not mentioned this model as one of the models I was considering using- but that could change. At this point, it's not clear to me why you brought this model up.

I brought it up because you seemed interested in efficiency. The 515G was designed and built to be the most efficient Altec driver. Check it out in the various cabinets (GPA still produces this driver in both HP and conventional forms...or they did the last time I checked). It uses aluminum v.c. wire and a really lightweight cone.

If you are trying to balance out HF to LF then fix it in the crossover, not by driver efficiency. Let the speaker's performance dictate the driver(s). If it were me, I would Bi-amp it and be done with the worry over sensitivity differences. But that is me. I'm not into the passive crossovers like others (no knock against them as I think of passive crossovers as an art form...it just isn't something that I delve into much...I've been using active crossovers for decades now).

I can say, for any future projects where I would be using a classic Altec horn cabinet (210, 211, 825, 828, 816), the GPA 515 LF is going to be my first pick...not to the exclusion of the other models just that it is my first choice.

[kip.duff]

Based on a talk I had with Bill at GPA and input from this thread, I've decided to address something I should have addressed a while back: crossover. I'm going to raise the crossover from 500 to 800Hz. The treble with my new turntable setup is even more aggressive than it was. Must be dealt with.

I've seen a lot of talk about Hiraga, but I believe it's 600Hz. Is there a decent stock JBL crossover for this application that can get me going till I scratch build one? I don't think I'm prepared to go bi-amp- but I don't know. Actually, REALLY don't know! I get that you use two stereo amps. But is there still a crossover in front of the amps? Using equipment like Pioneer SF-700?

Thanks......

[sguttag]

Yep, you us an active crossover before the amplifiers (two stereo, one 4-channel, 4 monos...whatever works for you). You can DYI the crossover if you want (a simple L-R 24 isn't too hard to build out of common parts) or go DSP with something like miniDSP (were they have both standard and HD grades) or some other brand of active crossover, analog or digital.

[Earl K]

Here's where you can get some Aquaplased diaphragms ( currently on sale for $80.00 > which is a great price ) .

JBL D8R2450SL diaphragm from Speaker Exchange (https://reconingspeakers.com/product/jbl-d8r2450sl-diaphragm)


:)

[Earl K]

Here's a good thread ( from Barry ) on how to EQ your 2360/2446/2450 horn-driver combo ( for a nice flat, listenable response ).

JBL 2360, Getting it Flat (http://www.audioheritage.org/vbulletin/showthread.php?37629-the-2360-Getting-it-Flat)


:)

[Earl K]

Here's another thread ( from Jerv ) about EQing the 2445 on a 2360. (http://www.audioheritage.org/vbulletin/showthread.php?27226-Converting-2445-to-wider-range-more-extended-HF)

Note; the 2445 has a couple of db less midrange output than the newer 2446/2450 type driver ( therefore Jerv's EQ advice is specific to the 2445 ).

:)

[Earl K]

Good Stuff here ( from our German + Norwegian members Gibber + oks81 & many others ) about their 2360 experiences (http://www.audioheritage.org/vbulletin/showthread.php?39033-JBL-2360-Compression-Driver) ( using various drivers ) .

:)

[kip.duff]

Here's where you can get some Aquaplased diaphragms ( currently on sale for $80.00 > which is a great price ) .

JBL D8R2450SL diaphragm from Speaker Exchange (https://reconingspeakers.com/product/jbl-d8r2450sl-diaphragm)


:)

Thanks for tip! but I need 16 ohm.....

[kip.duff]

Hi,
I compared the 515-16G with 416-16 and despite several trials and combinations I always preferred the 416-16 but I do not know more for the other versions of the 515, regarding the efficiency I simply doubled the boxes and an adjustment on my DSP XTA and voila.



Currently I'm looking for an amp to power the 416 because my PP2A3 lack a little juice for my rockier days. About the 2360 that I also owned for a while, I liked it but I much prefer the 2397 for the listening room that I have, with 2360 you have to be much further to appreciate, which is why they were designed so in a very large listening room the 2360 would be at their best. With the 2397 the image is better and they disappear, I like.
Keep going, you're on a good track.

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?

[kip.duff]

Yep, you us an active crossover before the amplifiers (two stereo, one 4-channel, 4 monos...whatever works for you). You can DYI the crossover if you want (a simple L-R 24 isn't too hard to build out of common parts) or go DSP with something like miniDSP (were they have both standard and HD grades) or some other brand of active crossover, analog or digital.

WOW. Just been looking at internet stuff on MiniDSP and XTA. Blowing my mind- bit of a learning curve but it looks exciting and worth getting into- and I plan to. Looks like similar technologies used in the Sonos Play 5 iPhone streamer I just bought and really like. One downside is need for extra cables. I have an Audio Research Classic 30 power amp I could use for LF.

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?

[JeffW]

Thanks for tip! but I need 16 ohm.....

They have them, but they are a bit more expensive

https://reconingspeakers.com/product/jbl-d16r2451sl-diaphragm/

[kip.duff]

They have them, but they are a bit more expensive

https://reconingspeakers.com/product/jbl-d16r2451sl-diaphragm/

Right- saw em $125. Teetering on them or coughing up $1700 for Truextent. Before I buy any fram, I wanna get horns so I can hear the originals Ti for comparison. Hunting for JBL 2397s and 2328 throats as I write.

[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 . (http://www.jblproservice.com/pdf/Network%20Schematics/3110%20Network.pdf)

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 ) (http://www.jblproservice.com/pdf/Network%20Schematics/3110A%20Network.pdf) 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 . (http://www.jblproservice.com/pdf/Network%20Schematics/3110%20Network.pdf)

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 ) (http://www.jblproservice.com/pdf/Network%20Schematics/3110A%20Network.pdf) 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 (http://www.jblproservice.com/pdf/Network%20Schematics/LX13.pdf) = 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 (https://www.parts-express.com/cat/crossover-components/21) 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.