Page 1 of 4 123 ... LastLast
Results 1 to 15 of 49

Thread: RLA style JBL/VOTT Club System, advice needed

  1. #1
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48

    RLA style JBL/VOTT Club System, advice needed

    I am looking on building a large hifi/club system for a party space I'm planning on opening, and was hoping for some advice on the finer details of this setup. A general plan that I have so far is 4 stacks around the room, each stack being:

    JBL 2395 lens horn with 2441 driver
    JBL 2404 or 2405 tweeter
    some form of altec box, can't make my mind up between the 828 or the 816, some advice here would be helpful
    some form of w bin, i'm thinking maybe double 18 berthas with eminence drivers, not enough room for a levan extension, looking for some advice
    4 x JBL bullet tweeters, 2402 or 075 for an array above the dance floor, not sure about which one, again some opinions would be great

    also dependant on the boxes I decide on is the available plans online, as I would be building all the boxes myself/locally

    I'm planning on running this system all analogue, with class a/b amps(crown, bgw etc), classic rotary mixer (og bozak or urei) analogue crossovers and eq (RLA/GSA, urei, bryston) and modified technic 1200s

    I'd always read about those old RLA disco sound systems from new york, and always thought it was in the past, until I went to a party and heard a high efficiency altec VOTT system with JBL acoustic lenses and tweeters. I was blown away by how great it sounded, and my plan is loosely based on what speakers I heard at that party. There's nowhere (that I know of close to me in the UK) that has all these speakers where I can A/B them, so hopefully someone on this forum will know the nuances of the speakers I'm looking at and can advise me on whats best.

  2. #2
    Senior Member RMC's Avatar
    Join Date
    Feb 2017
    Location
    Canada
    Posts
    596
    Hi budney,

    First, forget the "Hi-Fi" aspect this is all Sound Reinforcement stuff in a club system. Second, I don't know why (though I have some ideas about it) but way too many people, like in your case, keep repeating the same mistakes of mixing in same stacks short-throw and long-throw equipment without proper consideration to many acoustical issues involved. Since you're writing "a party space I'm planning on opening" my understanding is that this will be Inside, not outdoors. Therefore, long-throw stuff like the Altec 816/828 (equivalent to JBL's 4560A) are not really appropriate for normal-size indoor rooms, even if others do it, unless you have a VERY LARGE (HUGE) place, because the horn "concentrated" low frequencies will more likely be bouncing on opposite walls and everywhere around the place, while the mid/high frequencies with shorter throw will be dispersed according to the device's coverage angle and throw. It's not because you've seen it done elsewhere that it necessarily makes good sense acoustically...

    Since your top-end is already pretty much determined, with the most important of it being short-throw stuff (e.g. 2395 slant plates acoustic lens and 2404/2405 tweeters), then this is what you have to go with also on the bottom-end for it to be acoustically wise (i.e. technically sound) to avoid all sorts of sound quality problems. The 2402 bullet-type tweeters are more suited for long-throw applications. Mixing both types (short/long throw) close together is begging for trouble acoustically speaking. But then, it all depends on what you're trying to achieve: to impress the gallery with too loud bad sound or quality reproduction in a venue that MAY also turn out to be a difficult acoustical environment ?

    W bins, berthas and levan extensions, all of that is for long-throw... To be logical with the top-end you chose, and if you don't want to repeat the errors of others, you should be looking more, for low-frequencies, at JBL 4520/4530 type cabinets or even at vented-boxes which would make more sense than front-loaded horns/BR enclosures such as Altec 816/828, and the former are much less difficult to build.

    Based on some of the high/low-frequency choices you are mentioning, and with all due respect, it seems you have been improperly influenced by some of the technical non-sense circulated around here by some individuals who have clearly not done their homework. In simple terms, it's mostly a question of level, coverage and "reach" (i.e. spl, directivity and throw). I have written here before (in another thread) about some of this technical non-sense being thrown around here right and left, I quoted serious reference to JAES (and sent a personal copy) from some of the world-renowned JBL Engineers (Mark Gander and John Eargle) that what was mentioned by this member didn't exist (other than in his dreams) and guess what ? I still see that member here repeating again and again the same things as he did before in a new thread... Some people never learn! Or their ego refuses to admit they don't really know...

    To avoid repeating the errors of others and maximize return (sound quality) on investment, my best advice is do yourself a favour, consult some professionnal and respected manuals like: JBL's Sound System Design Reference Manual, Yamaha's Sound Reinforcement Handbook or John Eargle's Handbook of Sound System Design, or to some extent even JBL's Dance Clubs Systems Booklet 2003 (I tried to upload this last one for you but the file is too large to be allowed by this site, write me with an address I'll send it to you by e-mail). Regards,

    Richard

  3. #3
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48
    Hi Richard

    Thanks for the detailed reply, this is exactly the kind of advice I was looking for!

    In regards to mixing short throw and long throw equipment, that is just going from the system that I heard recently, which did use various different JBL acoustic lenses with various Altec vott boxes. I narrowed them down to the ones I thought sounded the best from listening to them in that room, but when listening to them I did think that it could have possibly been done better, that was just the first high efficiency club system I'd heard before and it inspired me to do it myself. It makes sense now that when you say the low range was long throw but the high short throw, I did notice some odd acoustical effects occurring when walking around the room. It's just that when comparing it to a normal modern club system, it sounds so much better, I was blown away by the clarity and not focusing on the shortfalls. Also I have nothing else to compare it to, all other systems I've worked with are awful modern digital things that are never set up correctly, with DJ's playing awful music from low quality mp3s.

    I was also going by some research I had done online, specifically for vintage disco club systems. These systems are spoke about as once being the best in the world, and I trust that the people who worked on them knew what they were doing. Some of the engineers who worked on them back in the day agree that what they did wasn't always technically correct, but it did sound the best...for instance they swear by the 2402 being hung in an array above the dance floor because thats what they want, full throw of the highs everywhere around the room. I think thats maybe perhaps why the system I heard recently still sounded really good. The highs were short throw, but the centre of the room was covered by the 2402's above the dance floor, with the long throw altecs being able to reach far into the centre.

    I have only been going by the advice/chat of professional engineers from that era, not someone who thinks they know audio in a forum. I have been told by modern professional engineers that pointing 4 stacks into the middle of the room is absolutely awful for the acoustics, but it makes for such a great party! Obviously I want to go for the best reproduction of sound I can, but I also want it to have that club thump and crack!

    Which sub would you advise on using? That is one aspect I am most unsure about, I wasn't convinced that the subs I had heard recently were the best for that room. I'm planning a decent size room, that could fit 300 people in at a push, and hopefully with some acoustic treatment budget permitting. I should also say that the kind of music I'm going to play is mainly disco/world music/pre 1990s dance music, which is why I'm trying to design it with a vintage aspect in mind.

    Thanks for the advice on the reading material, I had planned on picking up Yahama's sound reinforcement handbook as I'd seen the name thrown around a few times, I shall also look into the others. I've just had a glance at the JBL Dance Club booklet, and it does have useful information, but I feel like it was written with a modern dance floor in mind, which is something I'm trying to avoid. For instance the crossover I plan on using is in the DJ booth, so the DJ can change the levels of the subs and tweeters independently to great effect, you don't see these in clubs anymore. Also, I am trying to create a more 'hifi' club sound system, but without breaking the bank and going full class a. Is there anything that I could change/add to make it a bit more hifi and less PA?

  4. #4
    Senior Member Horn Fanatic's Avatar
    Join Date
    Jan 2013
    Location
    Boulder Creek, CA
    Posts
    399
    Quote Originally Posted by RMC View Post
    Hi budney,

    First, forget the "Hi-Fi" aspect this is all Sound Reinforcement stuff in a club system. Second, I don't know why (though I have some ideas about it) but way too many people, like in your case, keep repeating the same mistakes of mixing in same stacks short-throw and long-throw equipment without proper consideration to many acoustical issues involved. Since you're writing "a party space I'm planning on opening" my understanding is that this will be Inside, not outdoors. Therefore, long-throw stuff like the Altec 816/828 (equivalent to JBL's 4560A) are not really appropriate for normal-size indoor rooms, even if others do it, unless you have a VERY LARGE (HUGE) place, because the horn "concentrated" low frequencies will more likely be bouncing on opposite walls and everywhere around the place, while the mid/high frequencies with shorter throw will be dispersed according to the device's coverage angle and throw. It's not because you've seen it done elsewhere that it necessarily makes good sense acoustically...

    Since your top-end is already pretty much determined, with the most important of it being short-throw stuff (e.g. 2395 slant plates acoustic lens and 2404/2405 tweeters), then this is what you have to go with also on the bottom-end for it to be acoustically wise (i.e. technically sound) to avoid all sorts of sound quality problems. The 2402 bullet-type tweeters are more suited for long-throw applications. Mixing both types (short/long throw) close together is begging for trouble acoustically speaking. But then, it all depends on what you're trying to achieve: to impress the gallery with too loud bad sound or quality reproduction in a venue that MAY also turn out to be a difficult acoustical environment ?

    W bins, berthas and levan extensions, all of that is for long-throw... To be logical with the top-end you chose, and if you don't want to repeat the errors of others, you should be looking more, for low-frequencies, at JBL 4520/4530 type cabinets or even at vented-boxes which would make more sense than front-loaded horns/BR enclosures such as Altec 816/828, and the former are much less difficult to build.

    Based on some of the high/low-frequency choices you are mentioning, and with all due respect, it seems you have been improperly influenced by some of the technical non-sense circulated around here by some individuals who have clearly not done their homework. In simple terms, it's mostly a question of level, coverage and "reach" (i.e. spl, directivity and throw). I have written here before (in another thread) about some of this technical non-sense being thrown around here right and left, I quoted serious reference to JAES (and sent a personal copy) from some of the world-renowned JBL Engineers (Mark Gander and John Eargle) that what was mentioned by this member didn't exist (other than in his dreams) and guess what ? I still see that member here repeating again and again the same things as he did before in a new thread... Some people never learn! Or their ego refuses to admit they don't really know...

    To avoid repeating the errors of others and maximize return (sound quality) on investment, my best advice is do yourself a favour, consult some professionnal and respected manuals like: JBL's Sound System Design Reference Manual, Yamaha's Sound Reinforcement Handbook or John Eargle's Handbook of Sound System Design, or to some extent even JBL's Dance Clubs Systems Booklet 2003 (I tried to upload this last one for you but the file is too large to be allowed by this site, write me with an address I'll send it to you by e-mail). Regards,

    Richard

    RMC -

    More sensible words you have written are hard to find on this forum. Bravo. Frankly, I don't understand the fascination some folks on this forum have with that Jensen / RLA cabinet. Some kind soul on the forum a while back posted frequency graphs of the RLA box, and some dare to call it a sub-woofer. Odd, considering that dog begins to tank at 50 Hz.

    I agree with your advice for using the 4520 horn, or multiples of the 4530. IMHO, the ALTEC Stanley Screamer single and dual 15" bass cabinets make for outstanding sub-woofers. The drivers for those ( the 421-8H and 8H II ) are easy to find, and command less money than used JBL woofers. Plus, if re-coning is required, Bill Hanuschack has the correct kits for them.

    HF

  5. #5
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48
    Quote Originally Posted by Horn Fanatic View Post
    More sensible words you have written are hard to find on this forum. Bravo. Frankly, I don't understand the fascination some folks on this forum have with that Jensen / RLA cabinet. Some kind soul on the forum a while back posted frequency graphs of the RLA box, and some dare to call it a sub-woofer. Odd, considering that dog begins to tank at 50 Hz.
    It is my understanding that the RLA Waldorf, which is based on the Jensen, was not used as a sub? They were used on top of the big bertha/levan subs, as far as I'm aware. I've never seen or heard them, just going off what I've read online. I'm only looking at the RLA kind of speakers because everyone speaks of them as being the best dance systems in the world in the 70s and 80s.

    Quote Originally Posted by Horn Fanatic View Post
    I agree with your advice for using the 4520 horn, or multiples of the 4530. IMHO, the ALTEC Stanley Screamer single and dual 15" bass cabinets make for outstanding sub-woofers. The drivers for those ( the 421-8H and 8H II ) are easy to find, and command less money than used JBL woofers. Plus, if re-coning is required, Bill Hanuschack has the correct kits for them.
    So dual 15" will be sufficient? I only ask this because every club sub I've heard has been dual 18s.
    Would the 4520 scoop be a high fidelity speaker? The only scoops I've heard were awful and that put me off the idea of scoops, but that doesn't mean they're all bad. I'm just looking for a really efficient, dynamic system, would they provide that with the right drivers?

  6. #6
    Senior Member Horn Fanatic's Avatar
    Join Date
    Jan 2013
    Location
    Boulder Creek, CA
    Posts
    399
    Greetings Budney -

    I can understand why you were put off hearing some rear loaded enclosures. Typically, some folks have a habit of loading them with drivers unsuitable for use in horn cabinets with small chamber volumes such as the 4520 & 4520. Drivers with low Efficiency Bandwidth Product values do not operate well in small volumes. What you get is inarticulate bass. Not all cone drivers like to be horn loaded. Those with low EBP values tend to operate better in larger volumes. What you end up with is an enclosure comprised of more chamber volume than horn. For an enclosure of practical size, the horn would be so short as to be considered a discontinuity. To be honest, the majority of commercial folded horns behave more like a discontinuity, than a legitimate horn. As such, they perform much better in numbers.

    As long as horn enclosures are within half a wavelength from each other at the the flare rate frequency, at a full wavelength they behave as one.

    As for a vented sub enclosure, if dual 18" drivers are to your liking, there are scads of drawings on the internet for such enclosures. An 18" driver will move more air than a 15". A rear loaded bass horn such as the 4520 enclosure will be much more efficient than a bass reflex direct radiator.


    Good luck,

    HF

  7. #7
    Senior Member RMC's Avatar
    Join Date
    Feb 2017
    Location
    Canada
    Posts
    596
    Hi budney, and Horn Fanatic

    Since you are into vintage disco club speaker systems, here's how it looked like back then (having 60 yo soon, I was there often in the 70's and 80's, and had friends who build JBL horn-loaded enclosures for a living during that period). The top choice of the disco era, the king of the dance floor, was JBL's 4520 rear-loaded folded horn more often than not. BTW these are NOT subwoofers but rather high-efficiency low frequency enclosures (bass cabinets), they don't go very deep into the bass (-5 db at 42 hz), instead they provide some amplitude in LF response (60-100 hz range) to add punch or impact to some of the lows. They are short-throw cabinets (75 feet or less) and the horn provides maximum driver loading down to 42 hz according to JBL. In my view this is quite sufficient for the application.

    In terms of parts model numbers, the following is what it looked like most of the time in the good old days:
    4520 (2205 drivers)/2440 compression driver/2395 slant-plate (some 2390 folded-plate) acoutic lens/2405 tweeter(s).

    Now some comments regarding the above. First, though I really like their sound, I still think one has to be somewhat sadistic to himself to want to build horn-loaded cabinets on your own: too difficult, too much time, too large, too heavy, too costly, etc. I hope you have a large and well equipped woodshop along with a lot of muscle. Also, finding GOOD plans on the Web MAY be difficult. JBL never published official ones since this was probably a patented design. A German fellow has posted somewhere on the Web HIS plans for the 4530 (truthful to original?), but I don't recall seeing on the Net a complete and truthful set of drawings for the 4520. Former JBL Technical Director, George Augspurger did write a very long time ago about this type of cabinet in "The importance of speaker efficiency", Electronics World, January, 1962 (yes 1962), and on the last of his 3 page article he gave a drawing with most (not all) dimensions. Since the 4520 didn't exist officially until 1971 or so, the dimensions given by George are probably for the C-55 ancestor of the 4520. With that, along with JBL, Professional Series, Low Frequency Enclosures, May, 1980, you should be able to figure out pretty close dimensions using "reverse engineering" if need be. Nevermind the 4" pedestal shown by Augspurger if not required, these boxes were often placed directly on the floor.

    Second, finding proper drivers for these cabinets could be quite a job in terms of availability and suitable Thiele/Small parameters. JBL 2205 drivers are long gone (except for my still original and working pair from 1981!) and if you can find some they will probably have been reconed to something else like 2225 (not same Thiele/Small parameters, but some members have said they used it successfully). The other driver later recommended by JBL for 4520 cabinets was the E-140 which has T/S pretty close to those of the 2205. Again, they will probably have been reconed with who knows what. Adventurous fellows, like my friends who built these cabinets, did also use JBL's K-140/K-145/E-145 for their longer cone travel capability (X-max) so DJ's could extract from the cabinets every drop of bass output possible in use/abuse... The parameters of the K/E-145 were somewhat off for ideal performance but since it had even more cone travel capability that prevailed over reason and anything else... Fellow member Horn Fanatic did suggest in the past the 2220 driver was suitable here re T/S and I agree with that, however the 2220 would not survive long the abuses in the field(Xmax 2mm), and was never recommended by JBL for this application. However, 2220 was THE choice for front-loaded horns such as 4550/4560.

    Third, my advice if you want new drivers for these boxes is to look-up the T/S for 2205H/E-140 on JBL's driver T/S parameters list (jblpro.com) and try to purchase 15" drivers of proper dimensions and with as close as possible T/S as those of the two above, but preferably with higher Pe and X-max (min. 5+ mm) numbers since you seem to want to beat the hell out of the boxes to make lots of noise... Unless you use subwoofers, which personnaly I wouldn't do since it's not really required in Disco music, as in cinema sound for example, and not seen much in the good old days. Remember, Disco is more a matter of some amplitude in LF response, than very deep bass. Many people mix-up these two different things.

    Fourh, since you raised budget considerations and indicated being in the UK, you may want to look first at some new Fane drivers like the Sovereign Pro and Colossus lines; maybe Eminence or Peavey brands. Others from Europe could be too expensive since the Pound has lost some luster VS Euro: B & C, RCF, 18 Sound, Faital Pro, etc.

    Fifth, In any case, clever member Horn Fanatic gave you a pretty damn good suggestion with his idea of LF Stanley Screamers, which I didn't think of and haven't heard of for quite some time... Yeah, Stanley Screamers! If my memory is correct, these were developped by Altec Sound Contractor Stanal Sound USA in conjunction with Altec Lansing many years ago, right HF ? But they may not be easily available in the UK (location indicated by budney). BTW I'm glad Horn Fanatic (a knowledgeable horn guy around here) is keeping an eye on me in this Thread, this way I have to keep giving no less than 110%, otherwise he could be tempted to nail me to the cross, which is fine if I screw-up things. So far so good, HF ? My humble suggestion for subwoofer, which as said before I don't see as necessary, also to save some money, would have been something along the lines of JBL 4645C Cinema Sound Sub with 2242H 18" driver or even 2x15" cabs properly loaded (e.g. E-V DL 15W type, among many others).

    BTW from the Disco era I also remember seeing some Cerwin-Vega setups made around B36A and L48 something folded-horn cabinets. They still exist with different model numbers and some modifications. I can remember only one Club that used Altec Lansing equipment, it wasn't used much in Canada...

    "I am trying to create a more 'hifi' club sound system, but without breaking the bank and going full class a. Is there anything that I could change/add to make it a bit more hifi and less PA? " Yes, there is starting with your choice of equipment: rear-loaded horns, yes vs front-loaded horns, no. Compare frequency response curves of both types (e.g. 4520 vs 4560), it's evident; 2405, yes vs 2402 tweeters, no. Again compare frequency response curves it's also evident, you'll see the 2405 is a flatter (and "sweeter") device compared to the "gross" extreme output 2402 with 40° conical dispersion. 2405 tweeters were also often used by JBL in large Studio Monitors, I think this says it all for "Hi-Fi" aspect. Moreover, a "pack" of 2402 tweeters above middle of the dance floor, shooting in every direction, and far apart from the main boxes, may well raise phase and delay issues...

    In my view a 4520 cabinet loaded with proper drivers will certainly be more "High Fidelity" as you say than a front-loaded horn (e.g. JBL 4560 or Altec 816/828) in the application you are looking at. Finally, as for driver EBP value I could not have said it better than Horn Fanatic did. But I could say it differently (blink): these type of boxes are more compatible with such things as drivers having a low Qts number (e.g. 0.17 - 0.21 or so). Best Regards to both of you.

    Richard

  8. #8
    Senior Member Horn Fanatic's Avatar
    Join Date
    Jan 2013
    Location
    Boulder Creek, CA
    Posts
    399
    [QUOTE=RMC;406918]Hi budney, and Horn Fanatic

    A very well written and detailed analysis. It's nice to see someone in Canada who knows what he is talking about.

    I recommend using the 2220 in the JBL 4500 series rear loaded enclosures only for HiFi use. The 2220 is the commercial version of the 130A, and they both share the exact same T-S Parameters with the only difference being a more stout surround. The 130A was used in one model of the C34, and it works admirably in that enclosure.

    Regards,

    H.F.

  9. #9
    Senior Member RMC's Avatar
    Join Date
    Feb 2017
    Location
    Canada
    Posts
    596
    Hi Horn Fanatic,

    Thanks for you good words. I'll be out for a week of vacation. Going to spend some money on the beach in the USA. Good for your economy. I'm sure Budney will be in good hands. I'll read you guys when I'm back on July 15.

    Richard

  10. #10
    Senior Member
    Join Date
    Dec 2007
    Location
    wirral UK
    Posts
    658
    Quote Originally Posted by budney View Post
    I am looking on building a large hifi/club system for a party space I'm planning on opening, and was hoping for some advice on the finer details of this setup. A general plan that I have so far is 4 stacks around the room, each stack being:

    JBL 2395 lens horn with 2441 driver
    JBL 2404 or 2405 tweeter
    some form of altec box, can't make my mind up between the 828 or the 816, some advice here would be helpful
    some form of w bin, i'm thinking maybe double 18 berthas with eminence drivers, not enough room for a levan extension, looking for some advice
    4 x JBL bullet tweeters, 2402 or 075 for an array above the dance floor, not sure about which one, again some opinions would be great

    also dependant on the boxes I decide on is the available plans online, as I would be building all the boxes myself/locally

    I'm planning on running this system all analogue, with class a/b amps(crown, bgw etc), classic rotary mixer (og bozak or urei) analogue crossovers and eq (RLA/GSA, urei, bryston) and modified technic 1200s

    I'd always read about those old RLA disco sound systems from new york, and always thought it was in the past, until I went to a party and heard a high efficiency altec VOTT system with JBL acoustic lenses and tweeters. I was blown away by how great it sounded, and my plan is loosely based on what speakers I heard at that party. There's nowhere (that I know of close to me in the UK) that has all these speakers where I can A/B them, so hopefully someone on this forum will know the nuances of the speakers I'm looking at and can advise me on whats best.
    Look here, ask questions, Lee In Montreal who posts here was a contributor, have fun, there's a great thread(among others) here including layouts of Paradise Garage, cabinet plans etc from guys who do /have done it right down to the 4x2402 tweeter rigs; http://forum.speakerplans.com/levan-...957_page3.html

  11. #11
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48

    Wink

    Thanks RMC for the first hand detailed account of the good old days, great stuff! I've got a few comments/questions for you

    Quote Originally Posted by RMC View Post

    Now some comments regarding the above. First, though I really like their sound, I still think one has to be somewhat sadistic to himself to want to build horn-loaded cabinets on your own: too difficult, too much time, too large, too heavy, too costly, etc. I hope you have a large and well equipped woodshop along with a lot of muscle. Also, finding GOOD plans on the Web MAY be difficult. JBL never published official ones since this was probably a patented design.
    I agree that is a mammoth task to build a load of horn loaded cabs, but my brother in law is an excellent carpenter and the workshop where we work is well equipped for the task. Also the building next door to the workshop is a PA company that regularly build their own speakers so I feel confident I have the right resources, now I just need to find the time! but i'm happy treating this as a labour of love for quite a while.

    Quote Originally Posted by RMC View Post

    Second, finding proper drivers for these cabinets could be quite a job in terms of availability and suitable Thiele/Small parameters. JBL 2205 drivers are long gone (except for my still original and working pair from 1981!) and if you can find some they will probably have been reconed to something else like 2225 (not same Thiele/Small parameters, but some members have said they used it successfully). The other driver later recommended by JBL for 4520 cabinets was the E-140 which has T/S pretty close to those of the 2205. Again, they will probably have been reconed with who knows what. Adventurous fellows, like my friends who built these cabinets, did also use JBL's K-140/K-145/E-145 for their longer cone travel capability (X-max) so DJ's could extract from the cabinets every drop of bass output possible in use/abuse... The parameters of the K/E-145 were somewhat off for ideal performance but since it had even more cone travel capability that prevailed over reason and anything else... Fellow member Horn Fanatic did suggest in the past the 2220 driver was suitable here re T/S and I agree with that, however the 2220 would not survive long the abuses in the field(Xmax 2mm), and was never recommended by JBL for this application. However, 2220 was THE choice for front-loaded horns such as 4550/4560.
    All these stats and numbers don't mean much to me...but I've bought the yamaha handbook so will study up! I think I'll end up with what drivers I can find the cheapest/closest. Shipping and customs for 8 drivers from the USA will surely add up quickly...and that's on top of what I'd have to shell out for 2 pairs of JBL 2395s and drivers if I ever find them!

    Quote Originally Posted by RMC View Post

    Third, my advice if you want new drivers for these boxes is to look-up the T/S for 2205H/E-140 on JBL's driver T/S parameters list (jblpro.com) and try to purchase 15" drivers of proper dimensions and with as close as possible T/S as those of the two above, but preferably with higher Pe and X-max (min. 5+ mm) numbers since you seem to want to beat the hell out of the boxes to make lots of noise... Unless you use subwoofers, which personnaly I wouldn't do since it's not really required in Disco music, as in cinema sound for example, and not seen much in the good old days. Remember, Disco is more a matter of some amplitude in LF response, than very deep bass. Many people mix-up these two different things.
    I am planning to use subwoofers for this system, I may be designing it with disco as the main genre, but it will be a dance music system at heart. I feel like most dance music, especially from the 80s onwards like house music etc when drum machines arrived, would benefit from the extra reinforcement of the subwoofers. If it was purely 70s disco then I don't think I would bother, but I'm a big fan of the garage/new york style of 80s disco, which was written for dance floors with the huge subs! Also I expect that at some point more modern dance music may be played occasionally, and without subs the modern stuff would not hit as hard as it should.

    Quote Originally Posted by RMC View Post

    Fifth, In any case, clever member Horn Fanatic gave you a pretty damn good suggestion with his idea of LF Stanley Screamers, which I didn't think of and haven't heard of for quite some time... Yeah, Stanley Screamers! If my memory is correct, these were developped by Altec Sound Contractor Stanal Sound USA in conjunction with Altec Lansing many years ago, right HF ? But they may not be easily available in the UK (location indicated by budney). BTW I'm glad Horn Fanatic (a knowledgeable horn guy around here) is keeping an eye on me in this Thread, this way I have to keep giving no less than 110%, otherwise he could be tempted to nail me to the cross, which is fine if I screw-up things. So far so good, HF ? My humble suggestion for subwoofer, which as said before I don't see as necessary, also to save some money, would have been something along the lines of JBL 4645C Cinema Sound Sub with 2242H 18" driver or even 2x15" cabs properly loaded (e.g. E-V DL 15W type, among many others).

    BTW from the Disco era I also remember seeing some Cerwin-Vega setups made around B36A and L48 something folded-horn cabinets. They still exist with different model numbers and some modifications. I can remember only one Club that used Altec Lansing equipment, it wasn't used much in Canada...
    This is what I'm finding most difficult to understand...from the info I've found online about the Stanley Screamer subwoofers, they are a ported reflex box? Is that right HF? From what I've read online, again this might be completely wrong, is that you don't really want to use direct radiating boxes for dance floor subs. But again all I have experience of when working in clubs is folded horn double 18 subs, never of direct radiators. I feel like the full range system I want to build should be quite 'high fidelity', perhaps the subs don't need to be? Again I'm not experienced with different types of subwoofers so I'm not too sure what to go for. I gather from what you guys have told me that a folded horn/front loaded sub would not be right for me because of the throw/dispersion that cab produces? From what I've read, quite a few clubs in New York used Altec gear, is there someone out there who knows more?? I can only learn so much from reading online

    Quote Originally Posted by RMC View Post

    In my view a 4520 cabinet loaded with proper drivers will certainly be more "High Fidelity" as you say than a front-loaded horn (e.g. JBL 4560 or Altec 816/828) in the application you are looking at. Finally, as for driver EBP value I could not have said it better than Horn Fanatic did. But I could say it differently (blink): these type of boxes are more compatible with such things as drivers having a low Qts number (e.g. 0.17 - 0.21 or so). Best Regards to both of you.
    The final choice I'm trying to make is to go for the 4520 or the 4530. What are the benefits of having 2 drivers in one box compared to 1? Would I be able to run them linked to the same amp channel or would it be best to have a channel per driver for those boxes? and the same goes for if I were to make subs with 2 drivers in one cab, would I need to double the amount of amplifiers? The Stanley Screamer subwoofers are all 15 inch drivers, but every sub I have worked with previously has had 18 inch drivers. I guess since I plan to have a small dance floor with stacks of speakers surrounding instead of just at one end then 15 inch drivers should move enough air?

    Also will there not be phase issues with the 4520 when the front and rear waves meet? what are you opinions on that?

    thanks guys

  12. #12
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48
    Quote Originally Posted by cooky1257 View Post
    Look here, ask questions, Lee In Montreal who posts here was a contributor, have fun, there's a great thread(among others) here including layouts of Paradise Garage, cabinet plans etc from guys who do /have done it right down to the 4x2402 tweeter rigs; http://forum.speakerplans.com/levan-...957_page3.html

    Hi Cooky, yes I have read that thread thoroughly. I believe Lee In Montreal was planning on cloning the JBL 2395 lens, I shall definitely be in touch with him to see if he succeeded. Have you managed to do it too? I see you aren't that far from me, if you did manage to build any boxes based on the RLA style I would love to come and hear some of them.

    Thanks
    Budney

  13. #13
    Senior Member
    Join Date
    Dec 2007
    Location
    wirral UK
    Posts
    658
    Quote Originally Posted by budney View Post
    Hi Cooky, yes I have read that thread thoroughly. I believe Lee In Montreal was planning on cloning the JBL 2395 lens, I shall definitely be in touch with him to see if he succeeded. Have you managed to do it too? I see you aren't that far from me, if you did manage to build any boxes based on the RLA style I would love to come and hear some of them.

    Thanks
    Budney
    No Bud, just pointing you at another source,
    another direction.

  14. #14
    Senior Member Horn Fanatic's Avatar
    Join Date
    Jan 2013
    Location
    Boulder Creek, CA
    Posts
    399
    Quote Originally Posted by budney View Post
    Thanks RMC for the first hand detailed account of the good old days, great stuff! I've got a few comments/questions for you




    Also will there not be phase issues with the 4520 when the front and rear waves meet? what are you opinions on that?

    thanks guys
    Greetings, budney -

    Allow me to explain what I believe is the "phase issue" you're concerned about.

    Within a rear loaded horn design is the chamber the driver resides in. Technically, it is considered an acoustical low-pass filter, with a 6dB / Octave roll-off.

    The two elements that make the chamber an acoustical low-pass filter are the throat area and chamber volume. The throat area constitutes a mass, or as an electrical analogy, an inductance. The chamber volume constitutes a compliance, or as an electrical analogy, a capacitance. When introducing a cone driver in the mix, the acoustical properties of the driver must also be considered. It is in fact, another element in the acoustical impedance circuit treated no different than adding an extra inductor and capacitor to an electrical circuit. The math used to determine the roll-off frequency for an acoustical low-pass filter, and an electrical low-pass filter is the same. Both using values in Henries and Farads.

    When the acoustical reactance of the throat mass is at unity with the acoustical reactance of the chamber compliance, the result is a frequency that begins to roll off at 6dB / octave. Very much like a 1st order dividing network. It is at that frequency where the phase angle between the two is a 45 degrees, meaning, the front radiation of the cone is in phase with the radiation of the horn mouth. Above and below that frequency the speaker cone and horn mouth are not in phase. It doesn't matter, because high frequencies do not emanate from the horn, as low frequencies mostly emanate from the horn. Some on this forum insist the length of a rear loaded horn is 1/4 wavelength, but never define what the frequency is. I'm sure they mistakenly believe the 1/4 wavelength is based on the horn cut-off frequency, which in not correct. Such a condition would hold true for a transmission line, or acoustical labyrinth, but not a rear loaded horn. An acoustical horn is not a resonator. In order for a rear loaded horn to be in phase with the front of the cone, the horn length must be based on multiples of odd half wavelengths of the acoustical low-pass roll-off frequency.

    For example, consider a typical roll-off frequency of 300 Hz. The wavelength at 300 Hz is approximately 45". Divided by two is approximately 22.5". Three times 22.5 is 67.5". 67.5" is a typical length of a commercial rear loaded horn. If a longer horn is preferred, the next increment would be approximately 112". A longer horn will result in a larger horn mouth. A horn length of only 1/2 wavelength behaves more as a discontinuity, rather than a horn. Some might consider such, as a horn loaded port. There are however, different calculations for that arrangement.

    Now, consider a Compound Horn, where there will be a short horn at the cone front, and a long horn at the cone rear. The total length of both horns, not including the chamber dimensions, is still at an odd 1/2 half wavelength. If your front horn is 8 " long, then subtract 8" from the 67 ", which leaves 59" of rear horn length. At the roll-off frequency both horns are in phase.


    I hope I have been of some help.


    Regards, H.F.

  15. #15
    Member
    Join Date
    Apr 2017
    Location
    Uk
    Posts
    48
    took me a few days to process all that info

    Quote Originally Posted by Horn Fanatic View Post

    When the acoustical reactance of the throat mass is at unity with the acoustical reactance of the chamber compliance, the result is a frequency that begins to roll off at 6dB / octave. Very much like a 1st order dividing network. It is at that frequency where the phase angle between the two is a 45 degrees, meaning, the front radiation of the cone is in phase with the radiation of the horn mouth. Above and below that frequency the speaker cone and horn mouth are not in phase. It doesn't matter, because high frequencies do not emanate from the horn, as low frequencies mostly emanate from the horn.
    does that mean that any frequencies below the 'cut of' frequency emanating from the horn are not in phase with the cone? only at the cut off are they in phase?


    Quote Originally Posted by Horn Fanatic View Post

    For example, consider a typical roll-off frequency of 300 Hz. The wavelength at 300 Hz is approximately 45". Divided by two is approximately 22.5". Three times 22.5 is 67.5". 67.5" is a typical length of a commercial rear loaded horn. If a longer horn is preferred, the next increment would be approximately 112". A longer horn will result in a larger horn mouth. A horn length of only 1/2 wavelength behaves more as a discontinuity, rather than a horn.
    what do you mean by a discontinuity?

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Potential VOTT purchase - need advice
    By seven in forum Lansing Product General Information
    Replies: 15
    Last Post: 03-20-2007, 09:02 AM
  2. DIY VOTT A7 Info/Advice
    By camusmuse in forum Lansing Product DIY Forum
    Replies: 7
    Last Post: 06-26-2006, 11:39 AM
  3. Early Corner Horn Klipsch Style Help/ID Needed
    By david28613 in forum General Audio Discussion
    Replies: 5
    Last Post: 12-30-2005, 07:58 AM
  4. help! Advice for D131/075 system needed
    By jonathan z in forum Lansing Product Technical Help
    Replies: 1
    Last Post: 07-04-2003, 10:44 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •