JBL 4520 speaker replacement.

[Tube Radio]

I'll talk to the owner when he is ready to do the sound system and see if he wants to go with the 4520 or the version posted here that uses a single 18" driver.

I suppose some are using the 4520 as bass and the long throw cabinets as midbass perhaps.

Its nice that people have taken a design and improved on it. Shows that it was a good basic design to begin with.

I do agree the 4520 isn't a subwoofer.

I like how it sounds though. Brings sort of a realism to what bass it does produce and the bass sounds so natural and effortless probably due to less distortion and such because the speaker cones barely move while producing loud bass levels.

The other local rink has four and they sound ok.

One of theirs at one point was loaded with two drivers labeled concert on the dust caps. Probbaly car audio subs. That one would go deep far as bass response was concerned, but it didn't necessarily sound as natural as the other cabinets.

So here's what I'm thinking.

1. 4 of the 4520 or 8 of the 18" version for the bass
2. 4 bullfrog or Altec 816 cabinets or 8 of the same for 90-800Hz
3. Horns for the treble 800-16KHz
4. New Yamaha amps with built in DSP.
5. Either a passive crossover on the midbass and treble horns or double the amps and the built in active crossovers.

EDIT:

Now if I build the 18" version of the 4520 what frequency should the speaker be crossed over at?

Also what driver should I use since the PD-1850 is not available in the USA?

[Lee in Montreal]

Your challenge will be with your choice of horn/driver for 800Hz-16Khz
I suggest you look at the JBL 2360. It will do that. Easily.

BTW Contrary to what was pretended in the post before yours, the 4520 doesn't have a 13ft horn. Who ever wrote that never had or worked with these cabs. They are 8ft vs 7ft for the 4530. Which is why they shift the pass band slightly lower. Gaining a bit of bottom end, loosing a lot of kick. ;-) 8ft horn is 35Hz cut-off and peak at 88Hz (frequency of the "round" bassline) with phase reversion at 105Hz. While 7ft is 40Hz w/ peak at 100Hz The frequency of the kick) and phase reversion at 120Hz

BTW Here's what I had in my basement. Therefore talking from experience and recognizing what these cabs are, and what they are not. ;-)





Which is why I suggested that if you want really deep bass from a bass horn, you will have to go BIG and build some Berthas as they reach an easy 25Hz with the long Levan extension. You need to experiment by yourself before starting to give advises to that investor. So, go out and listen to as many systems as you can... And remember that what as great for 1984' music might not fit in 2017 ;-)

[RMC]

Sorry, I have not been able to post the attachements, I have tried many ways as indicated on the site but it just won't work... If you have an e-mail address I can forward them directly to you for posting if you wish.

As for Lee's comment about the length of the 4520 folded horn, he should read what the designer/manufacturer of that horn says: JBL, Professionnal Series, Low frequency Enclosures, dated May 1980, page 2 where it specifically states " Model 4520 dual driver horn, thirteen-foot folded horn ..." Yep ! At the same time having a look at the frequency responses provide by JBL for 4520 showing it is already down -5db at about 42-3HZ, -10db at 37-8HZ and -15db at 32HZ ... JBL also warns about excessive cone excursion and possible damage, suggesting power input be restricted at very low frequencies. Is Lee pretending to be more knowledgeable or smarter than JBL Engineering ?

Richard

[Tube Radio]

Lee, my plan is to go with the 18" scoop you posted the plans to and do two per speaker stack as you suggested. That would get me to 30Hz and I can set the high pass crossover of the Yamaha amp at that frequency. I will need a suitable driver for that cabinet though as the one recommended on the plans isn't available in the USA.

For the 800-16KHz frequency range in a thread I started about the 811B horn (fairly easy to get for not much money on ebay) someone mentioned the BMS 4550 as a suitable driver.

I have indeed heard some 4520 cabinets at the other local skating rink and they sounded good far as bass goes. They did not reproduce the extreme low bass though, but still sounded great.

Figure 30Hz with two of those super scoopers per stack is plenty low enough for a skating rink.

I've been to many different skating rinks and what always sounded best to me were the ones with the older systems.

The current rink I'm designing the system for I went to about 5 years ago when everything worked and I thought the 4520s sounded so good.

In a way I think the quality of the bass somewhat makes up for what isn't being reproduced due to the 4520s not going low enough.



EDIT:

Ebay is my friend.

Found four 811B horns and four 4560 cabinets. Without drivers of course.

Forwarded the info to the new owner to see if he wants to buy them.

If so the horns and midbass will be taken care of.

All that will be left is to build the super scoopers.

[RMC]

From the latest pictures provided by Lee of his former 4520 cabinets, the black glue job on the dust caps is a sign that something went wrong... Dust caps were probably cut open for some reason. Are these 2205 reconed to 2225 ? Or 2225-6 repaired ? Or rotten foam or other debris removed from the gap? If 2225-6 drivers or 2205 reconed to 2225 then one must realize the parameters of the 2225-6 are different from the original intended driver for 4520 the 2205. The 2225 at 5 mm Xmax has a little more cone excursion which may explain why he could hit them harder (not much deeper) in the bass range (the 2226 has even more Xmax at 7.6 mm). The following example illustrates some evident differences in the following sequence (2205/2225/2226): Fs 30/40/40HZ; Qts .21/.28/.31; Vas 297 l/170 l/175 l. As can be seen the 2205 had a much lower Fs (free air resonance) and much larger Vas (suspension compliance equivalent volume). This is why I suggested a possible E-140 for replacement driver in addition to market availability...

With regards to the stacking issue "... my plan is to go with the 18" scoop... and do two per speaker stack ... That would get me to 30 HZ... Figure 30HZ with two of those super scoopers per stack..." The cruel reality is that if one cabinet doesn't go down to 30HZ then two won't go either, regardless of whishes. Speaker engineer Drew Daniels of JBL has explained that a long time ago in Modern recording Magazine. Moreover, the additionnal document, from John Eargle and Mark Gander both world-renowned engineers from JBL, I transfered to you (Tube radio) today was also for that purpose. Look at pages 5 and 6 in PDF numbers or pages 416-7 from the original Journal of the Audio Engineeering Society, more specifically Fig. 9 on page 416 and the "Mutual coupling" section on page 417 to realize that what you plan to get (deeper bass) by stacking two of the same cabinet doesn't exist. Same frequency respose but higher output, that's it, no further bass extention from mutual coupling or stacking. Sad but true... Sound is a science.

As for the 4560 enclosure your best bet is probably again the E-140 driver (but see JBL low-frequency enclosure document). Regards,

Richard

[Lee in Montreal]

Dear RMC

I have absolutely no clue where you are going. Have you ever owned or measured a 4520, or are you just one of these internet experts? 8ft is what the horn is.

If you can get 12ft out of this horn, we have a new genius.



As for the dust caps missing or repaired from the 15" woofers, again, I have no clue what you're talking about. They are still there, and the coils never bottom out.

And BTW I really don't see what you're doing in this conversation. Do you have any background related to the topic that you wish to share with us?

BTW Junior member should learn how to behave... ;-)

[1audiohack]

No budget yet.

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.

I have and I agree, they can sound good. I am a high efficiency guy too.

I am guessing it would be out of the budget but you could swing a single Danley J1-94 in a corner and never have to work on anything again. But what's the fun in that right?

All the best,
Barry.

[Tube Radio]

RMC, the cabinets would be side by side not stacked.

[1audiohack]

Hi Tube Radio;

I want to clarify that I am not trying to talk you into, or out of anything.

I just know that there is some smashingly good sounding new stuff out there, that's all

Hope your fun continues.

Barry.

[Tube Radio]

Agreed there are good new things out there, but to get as good as the vintage stuff would it cost more?

[RMC]

Hi Justin,

Unfortunately for you, mutual coupling of identical bass cabinets means "closely spaced driving units", so no matter if it's on top, under or side by side... However, you will gain in output, though not in deeper bass.

I'm glad to have contributed relevant and valid info to help you make an informed decision, this is what this site is all about, regardless of whom/where it comes from. It's great to have many point of views and various sources of info before committing to such an important project. No one (including me) has exclusivity of knowledge or expertise. I hope the numerous documents I sent you will be helpful.

Finally, that my colleague "senior member" misbehaves himself by loosing his cool and politeness over other contrary contributions tells a lot, it's a very old trick used when painted in the corner or not having a valid argument to debate or undo well established facts: you attack the messenger... Doesn't bother me.

By the way, the length of the 4520 horn as stated by JBL does make sense if you really think about it, however one has to know how to calculate it too !

Regards,

Richard

[Lee in Montreal]

Hi Justin,

Unfortunately for you, mutual coupling of identical bass cabinets means "closely spaced driving units", so no matter if it's on top, under or side by side... However, you will gain in output, though not in deeper bass.

I'm glad to have contributed relevant and valid info to help you make an informed decision, this is what this site is all about, regardless of whom/where it comes from. It's great to have many point of views and various sources of info before committing to such an important project. No one (including me) has exclusivity of knowledge or expertise. I hope the numerous documents I sent you will be helpful.

Finally, that my colleague "senior member" misbehaves himself by loosing his cool and politeness over other contrary contributions tells a lot, it's a very old trick used when painted in the corner or not having a valid argument to debate or undo well established facts: you attack the messenger... Doesn't bother me.

By the way, the length of the 4520 horn as stated by JBL does make sense if you really think about it, however one has to know how to calculate it too !

Regards,

Richard

Well. Where to start...

Placing 4520s side by side, or stacked on top of each other, as long as their mouth are together does use the coupling effect that raises the overall output, but it will also increase the output of the lowest frequency the horn can play. It is one of the rules from the Keele papers where the circumference of the mouth needs to equal half the wave length of the lowest frequency the horn can play. With its 8ft horn that allows 35Hz as the lowest frequency, the mouth's perimeter needs to be (344m / 35) /2 = 4,9m... Otherwise that 35Hz will be weak. 4,9 meter is far from what the mouth is with its 33" width (0.84m) and 28" height (0.7m) = 3 meters. Far from 4,9 meter... But put two 4520s together and the combined perimeter becomes 4.76 meters which is pretty close from half the 35Hz wave length and will get you that stronger 35Hz. This is exactly why bass horns are positioned in groups. To increase their combined mouth perimeter. Not just for coupling.

As for the 12ft horn of the 4520, if we agree that the 4530's horn is 7ft, then compare the drawings of a 4520 with the ones of the 4530, and let's try to find that 5 extra feet of horn. ;-) It is common knowledge among 4520 afficonados that JBL published a typo that time. ;-)

4530 - 7ft / 40Hz horn -



4520 - Where are the 5 extra ft compared to a 4530 ? ;-) If it were indeed a 12 ft horn, then the 4520 would be a 28Hz horn. Which it is obviously not.



Tube Radio, if you can make four groups of two 4520s in your rink, you can have fun. Put them in the corners to get some extra loading and they can sound great. You can find some well built 4520s for cheap these days. But perhaps you should have them built better than originally. Thicker outer panels and more bracing.

[1audiohack]

Agreed there are good new things out there, but to get as good as the vintage stuff would it cost more?

For sure. Big vintage stuff can be had for pocket change.

I have not been in a roller rink in ages but don't remember any of them sounding too good. Loud is easy, multiple sound sources and lots of reflective surfaces act to degrade the sound quality.

For what it's worth, a single Danley J3-94, a 90 x 40 degree fully horn loaded box costs about $23,000. USD and you would need a sub for that one. It's been too long since I priced a J1-94 but they are more.

The only reason I brought it up was that just one of these will, eq'd to run with no sub in an enclosed space like yours would play way louder than any remotely sane person would ever tolerate and as such not be in danger of being damaged, and sound spectacular doing it.

I have one system comprized of RCA 9462 bass horns with Community M80 mid bass horns and Community RH60's that sound stunningly good. But, they are seven feet wide and 11 feet tall, and one J1 will best them in any metric, except cost.

I hope you get to play there again.

All the best,
Barry.

[Tube Radio]

Lee, would it be better to pair two super scoopers versus two 4520s?

Sure I could probably buy some 4520s, but shipping would be expensive.

With the 4520s though I already know what driver will work, but for the super scoopers I have no clue what driver works unless I can import the drivers listed in the plans.

What I need to do is look at all the components I have selected and see how tall the speakers will be. If they are taller than a normal person it may be that I have to suspend the 811B horns from the ceiling or mount them to the cabinets at a downward angle.

1audiohack, many don't sound good, although I was in one in Atlanta GA a few years back that used older three way speakers that had an aperiodic chamber for the midrange (electro voice I think) and it blew me away with how good it sounded.

What I wonder is this.

If instead of building two super scoopers I have one built twice as wide and have both 18"s in the same cabinet would it be any better?

LOL wow the 4560s are 7" deeper than the super scoopers and 12" taller.

Looks like the speaker stacks will be fairly tall minus the 811B horns.

Length 30" 2 1/2'
Width 60" 5'
Height 84" 7'

Going to be some impressive speaker stacks.

That's provided I go with the super scoopers and the owner did buy the 4560s.

If he didn't buy those then I'll see if that one bullfrog cabinet is still there and have four of those made.

With the DSP built into the Yamaha amp I am using I should be able to make these speakers sound good.

I can set the high pass to the frequency at which the horn starts to unload at which will keep the driver from self destructing itself.

I noticed on the plans for the super scooper it lists a cutoff of 38Hz which is only 4 Hz lower than the 4520. That said what is the real benefit to the super scoopers?

Also the speakers don't necessarily have to all be stacked on each other.

I could stack the super scoopers with their mouths together then on the right or left put the 4560 and 811B on top of it and I could make a place under the 4560 for the amp to be mounted in as I'd need to raise the 4560 up some off the floor so it can be at ear level for the average height person.

Three of the corners won't be a problem to arrange the speakers like that. The fourth corner would require altering a wall which shouldn't be that hard to do.

[Lee in Montreal]

Hi buddy

You already know what the 4520 sounds like. That's a first step. It will sound even better once you start shaping the sound with a digital crossover. But hey, you already understand some of the limitations.

Now to the 18" Superscoopers. You will never how they sound from simply reading articles on the internet. You need to step in and build a set. Then only you will understand what they do. Or don't do. Sure you can load them with brand new and expensive drivers, but you can also experiment with some JBL 2240 w/ Fs =0 and Qt=0.23 or equivalent.

Only by experimenting will you know what works best. Or go to exterior events, see what is used for sound reinforcement. Compare. Is that the sound you like? Also, considering that you will most like play CDs and newer music where there's a lot of content below 60Hz, I'd make sure that the bass cabinets you use will give you plenty of "meat" in that range. And BTW, I would still consider building and installing Berthas for deep basses. Check on the net if there's a club using them in your state. Then go travel.

BTW Have fun reading this.

http://www.whathifi.com/features/ins...d-sound-system



And that was the original Ministry of Sound stack that was sold off a while ago and restored by an enthusiast in England.