Posting about this has really made me want a couple of these for my own stereo and makes my 12" subs seem quite inadequate, but I don't have the space.
Posting about this has really made me want a couple of these for my own stereo and makes my 12" subs seem quite inadequate, but I don't have the space.
Let us know how you are progressing with the rink's sound system.
Unfortunately I cannot do anything until they get the money to put in the sound system.I do agree on using two amps per speaker versus a single amp and passive crossover.
Time for a much needed update.
Had some bad news that the rink was closing for good after this past Sunday night session which it did do.
The good news is that in talking to someone associated with the rink they have someone lined up to possibly buy the rink and I told the person I'd offer to help the new owner in any way I can so it is still possible for the sound system to be realized.
Going to present the new owner with two options.
1. Two amps per speaker stack no passive crossover for $5,380.32
2. One amp per speaker stack with a passive crossover for $3,780.32
What I might do is this. Get one woofer and one horn driver and try the 800Hz passive crossover just to see how it sounds. If it is good enough then I may go with that option in order to save the new owner some money as there's a lot he/she will need to do to the rink and that will cost a lot of money.
That said later on the system can be upgraded with separate amplifiers for the Yamaha horns when the owner has the money.
Another thought is this.
Use one amp per speaker for the 4520 and Bullfrog then use one amp per pair of speakers to drive the Yamaha horns. That way only 6 amps are needed versus 8.
Also if the drivers in the Bullfrogs are good I may not replace them, but I will see if the drivers have a number I can look up to find the maximum power they can handle. That way I'll know if I still need to replace them. I know that most likely the system will never run over 100 watts of output, but at the same time the system needs to be fairly idiot proof.
I will talk to the new owner and perhaps work out some sort of guidelines for using the PA such as only allowing people who know what they are doing to operate the PA and having it to where if something breaks and it is determined to be from abuse, whoever was supposed to be operating the PA at that time would pay for the necessary repairs. I would also suggest to the owner that he/she put it in writing and make each employee and guest DJ sign a copy.
A further update.
Found out the building had went into foreclosure and that the owner took all the sound system stuff claiming it was his.
Don't know the legality of what he did given he isn't the original owner and didn't buy the stuff with his own money, but if the potential new owner can't get it all back I'll have to start over from scratch on building the system.
My temptation is to have some 4520 cabinets built with modified plans that extend their low end down lower than the stock cabinets.
Then perhaps have some JBL midbass horns built and find some 811B horns unless another horn would be better.
Is that a good idea or would something else be better?
What I don't know is if the owner took the empty Bullfrog cabinet. If not it could be possible to have a good speaker box builder duplicate it.
Build a set of Berthas with Levan horns. They house two 18" each. Load them with JBL 2442 woofers. They are the best bass horns on earth. Make a little internet search. ;-)
Buy four 4530, not two 4520. The single 4530 has a much better kick than the 4520. Those are dirt cheap on the used market and not worth wasting time building.
That would work, but space is limited so I'd have to stick close to what was there or smaller.
Now of course if I can find some 4520 cabinets used that would be good.
Now concerning the bullfrogs if a similar Jbl horn loaded midbass cabinet is readily available used I might go that route.
If you want to reach (slightly) deeper with those 4520s, you will need to increase the perimeter of the 4520s mouth. That is done by placing them side by side. So, you'll need two cabinets per side.
If you build them, then nothing can keep you from adapting them for 18" drivers. Get some JBL 2240 with Fs30, they are usually quite cheap.
How to build 18" a superscooper. Have a CNC shop groove the side panels for you. You make 8 of them, grouped by 4 units for deep 30Hz bass.
4' tall x 2' wide x 2' 6" deep
https://www.youtube.com/watch?v=pYy-iitwY6I
Grouped 4 x 4
https://www.youtube.com/watch?v=UyMCbrECAow
Very nice.
Will have to keep in touch with my contact and see if they get the sound system back and if not I'll present them with the option to build the cabinets or go some other direction.
If the sound system cannot be recovered and I do not have a Bullfrog cabinet to duplicate would building or finding some JBL 4550A speakers be ok for frequencies from 90-800Hz? If I have to build them would the same drivers I planned on using for the 4520 work for these?
Perhaps then for the treble horns some 511B horns with a good quality driver.
The new owner is just going to buy everything new so I'm going to present him with this idea:
Buying 4520 cabinets or building the ones you showed the plans for here.
Buying Altec 816 cabinets or building them from plans or if the empty Bullfrog cabinet is still there having someone duplicate it.
Buying 811B horns and some BMS 4550 compression drivers.
I could of course do a search for the Yamaha horns and buy them and the eminence drivers or perhaps find some other vintage horn that can load down to 800Hz and fit the BMS driver.
It may be easier if I were to use a super tweeter like some of the Altec three way cabinets used with the horn loaded woofer or perhaps find four of those cabinets with all the drivers.
I still am thinking of the 811B and Eminence PSD-2002-8 driver as I know that driver on that horn is flat from 1.2-16KHz, but I know the horn loaded midbass cabinets will not go up to 1.2KHz and as such that driver cannot be used.
That said if I do go with the 811B horns I will need to have them painted unless I can find four black ones.
I'm going to try and make a good case to the owner as to why new speakers aren't the best way to go far as ultimate sound quality is concerned.
This is very budget dependent.Originally Posted by Tube Radio
Much has been learned in the 40+ years since all the enclosures talked about here were made and used. It seems for a time things got worse and the big old stuff really did sound better but those days are now past. There are point source boxes with well defined pattern control that will absolutely smoke the big old black stacks of yesteryear. I have lots of the old stuff and some of the new stuff and the old stuff almost never comes off the mezzanine anymore.
I have not been able to see in the pictures any details about where in the room and how the system is deployed. Do you have any pics with the lights on?
Is there a budget yet?
Barry. (Who is not an audio equipment sales person).
If we knew what the hell we were doing, we wouldn't call it research would we.
No budget yet.
Here's a video showing the speaker locations https://www.youtube.com/watch?v=8cNCbA3srl4
Also as seen in the video there are some speakers in the wall and hanging from the ceiling. Should I put speakers back in those locations or will one in each corner be enough?
The rink is the typical oval shaped skate floor and one speaker stack is in each corner.
I've thought about new speakers, but the older horn loaded speakers were so efficient and don't require much wattage to go loud.
I'd prefer to stay away from new speakers as the older speakers do sound so good.
If you have ever heard a JBL 4520 cabinet with the right drivers installed producing bass at extremely high levels with the cones barely moving you'll understand why I prefer to go vintage.
With all due respect to my fellow members, I've seen some questionable technical stuff going by here...
I know a thing or two about these cabinets because many years ago I knew people who earned a living making those in their shop, as well as 4530, 4550, 4560 plus others and selling them to sound contractors. I've also been around these cabinets for as long as I can remember in clubs or other places, as well as having a lot of technical info in my library on them. By the way, I've read sometime ago (can't remember where) that JBL had supposedly sold the patent for these enclosures to Ampex ???
4520/4530 type of cabinets are rear loaded folded horns (13 ft. and 7 ft. respectively) basically designed for short-throw applications (e.g. clubs, discos). 4550/4560 type of cabinets are ported front loaded horns basically designed for long-throw applications (e.g. stadiums, outdoor concerts). None have deep bass.
"Mixing and matching" these two types of cabinets in the same stack in random ways, as seen on some pictures in this thread, doesn't make sense acoustically speaking, though different stacks for each type, at different locations (apart), could make sense to reach different audiences (close-by and further away people).
JBL's low-frequency enclosures document (see attached) is pretty clear on intended purpose of these cabinets plus on the go or no go issues related to bass frequencies, very interesting and will dissipate misconceptions about them. THEY ARE NOT SUBWOOFERS, contrary to popular belief, they are not designed to go deep (30-40HZ), but rather for efficiency and "punch" amplifying some part of low-frequencies giving impact to the beat in dance music. People routinely try to extract high level deeper bass from it than what it's really capable of. Proof in the Xmax of the most suitable JBL drivers: most limited at 5mm or less, far from subwoofer range. Therefore, to avoid busting other drivers and distortion a steep high-pass filter in the 40-50HZ is a must. EQ should then be applied as required with the 63HZ slider (no less). Better be safe than sorry...
George Augspurger (a former technical director at JBL) wrote about these speakers as far back as in 1962 (see attached) with construction plan and dimensions on page 3).
The widely used setup with with these short-throw cabinets in the 70's and 80's was with 2205 woofers which I have original (obsolete) replaced by the 2225 (obsolete) now replaced by the 2226... not the same T/S parameters but the nearest JBL has in the catalogue... Moreover, a number of guys did load these short-throw cabinets successfully with the higher efficiency/sensitivity K-140/E-140 musical instrument bass driver since the parameters of the 2205 and K-140/E-140 were pretty close. Be aware the latter has a more rising mid response for bass guitar sound harmonics, hence a 100 db sensitivity rating compared to 97 db for 2205 but has a flatter response. These drivers were made for smaller volumes (e.g. inside 4520/4530).
The rest of the usual setup was JBL's 2440 horn driver/2390 folded-plate or more often 2395 slant-plate acoustical lens, again for short-throw applications, and 2405 tweeters.
JBL's Acoustic lens family document along with their intended purpose is also attached here (see)
Again, mixing randomly long-throw radial horns with acoustical lens in very close proximity as seen in some pictures here is begging for trouble since it isn't acoustically wise... (see attached document by Augspurger also from 1962 ! , about acoustical lens and how they work). A LOT of people don't really know how these project sounds. Some pictures here in this thread show lens way up there on top of a tall stack of cabinets/drivers, a configuration more common for long-throw devices, probably thinking the slant-plates project sound downwards, which is not the case, thereby creating a sound coverage problem). Extremely clever horns made to increase horizontal dispersion !
As a general simple rule-of-thumb, for long-throw you want more directivity, while for short-throw you want more dispersion of sounds. Cinema sound/home theater sound is somewhat of an exception to this for reasons related to the perceived location of sound (like dialogue). John Eargle(RIP) from JBL wrote a short but interesting article on this. Klipsch's home theater speakers, with Tractrix horn, illustrate that point.
Finally, I'm not surprised the Peavey driver died since it may not have been suitable for this application, in addition to the fact that most people beat the hell out of these boxes. Before choosing, one must find something with comparable T/S parameters/specs, as I have done above re 2205/K-140/E-140. You should try to have two of the same driver in a 4520 cabinet for enhanced performance. Here in point form some notes on that: used 2205 same specs if original(?) but probably reconed to 2225, same specs?; used 2225 probably reconed, same specs?; new 2226 expensive, same specs?; used K-140 probably reconed (to E-140?), closest specs; used E-140 probably reconed, closest specs; used K-145/E 145 probably reconed, specs not far off. Most probable JBL candidate? E-140 i guess, for availability, if in good shape and $ ok.
I hope this helps you in getting a good old 4520 back in shape for a long time. I liked them. Regards,
Richard SORRY, GOTTA GO I'LL POST THE ATTACHMENTS TOMORROW.
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