JBL 4520 speaker replacement.

The local skating rink I go to has four JBL 4520 cabinets used as subs.

One caused a woofer to self destruct by someone pushing frequencies under 30Hz through the cabinet at high levels and the horn unloaded causing the speaker to go into over excursion thusfore destroying itself.

I removed the blown driver and it is a Peavey Black Widow.

Pretty sure that is not a proper speaker for that cabinet.

What currently available driver would be a good choice for those cabinets?

The drivers are wired in parallel for a 4 ohm load, but I'm thinking a 16 ohm driver would be better as I would have an 8 ohm impedance per cabinet which will put less load on the amplifier.

http://www.jblpro.com/pub/obsolete/L...nclosures2.pdf

This will tell you, unless there is something newer that will work. I see lots of E140, 2220, and 2225 drivers for sale. The E145 is rare.

Ideally I would want a currently made driver if possible.

The cabinet with the black widows in it did actually sound ok, but not great. Seems like the bass under 40 Hz is not there much at all.

At another skating rink that has cabinets like these they had a pair of drivers in one cabinet that had concert on the dust caps. Now those sounded good and even had good bass under 40Hz.

If I cannot find a currently produced driver for these speakers I wonder if there's a car audio sub that will work?

Quote:

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Originally Posted by Tube Radio

The local skating rink I go to has four JBL 4520 cabinets used as subs.

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That would be a first mistake ;-) The 4520 is NOT a sub. It is a bass cabinet. ;-)

The ideal woofer has a low Qts. The original 2205 had something like 0.2 and good old 2225 have 0.28

I suggest not to go with 2226 which is clearly a bass reflex driver (and it would require major eq to cut 100+ Hz)

Or sell the cabs and get bass reflex cabs with modern drivers requiring gobs of power to feed. ;-)

When the place was originally built they were most likely used as bass cabs, but I just call them subs because they are used like a sub would be.

In that case most currently produced pro audio subs should be considered bass cabs given most only go down to 40Hz :D

Quote:

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Originally Posted by Lee in Montreal

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I suggest not to go with 2226 which is clearly a bass reflex driver (and it would require major eq to cut 100+ Hz)

</snip>

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The 2226 is very similar to the 2225. The params fs, Vas, Qt are that similar that each of them can be used as a plugin replacement for the other.

Ruediger

Quote:

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Originally Posted by Ruediger

The 2226 is very similar to the 2225. The params fs, Vas, Qt are that similar that each of them can be used as a plugin replacement for the other.

Ruediger

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I currently have half a dozen units of each and find they don't sound alike at all. While I consider the 2225 a bass driver, the 2226 is more a mid bass driver with hyper "enthusiastic" midrange requiring a lot of eq to give any decent bass. Looks like there's more to a woofer than just T/S specs.

But hey, the OP is free to experiment. He may well try a set of 2226 woofers,but he still wont get 30Hz sub bass from that driver and that cabinet.

Lee

In the past I have seen some drivers listed as being designed for horn loaded cabinets and scoops so maybe one of those drivers will work?

I'll look up some tonight and post them here.

The crossovers used have a high pass filter of 25Hz. Will that be enough to protect the speakers from the low frequencies this cabinet cannot handle.

I looked online and found a thread on here from 2013 where a member used these woofers in the 4520 bass cabs he built

http://www.parts-express.com/dayton-...oofer--295-034


Would that be a good choice?

More than likely I will power them with this amp as it has built in crossover and other processing things.

http://www.parts-express.com/yamaha-...ohms--247-6156#!

Fs is 31Hz and Qts is .27
And they are dirt cheap.

Why not try them? :)

But remember that by design those 30Hz cabinets have a 60Hz fundamental (where peak is).

Original 2205 woofers had Fs30Hz and Qts .20

4520 response

http://oi52.tinypic.com/29x6ly1.jpg

If you want some serious 25/30Hz sub bass cabs, you should perhaps look into building some Bertha horn loaded cabs w/ Levan horns. These will make you spill your guts on the dance floor. ;-)

http://a4.l3-images.myspacecdn.com/i...e1401241/l.jpg

Please, show us pictures of your 4520s... I had a set in my basement and loved them. But the restroom furnitures and cosmetics didn't agree on the floor above. ;-)

Very nice speaker stack there. :yes:



I will have to take some pictures next time I go to the skating rink.

The cabinets are in good shape. Just some wear and tear on the front bottom since these sit right at the edge of the skate floor.

I do plan on trying those drivers though. Will get two and see how they sound in one cabinet before buying more.


These will be paired with one BFI Bullfrog front horn loaded cabinet per bass cabinet which has a 15" driver and a slot port firing out the front and will be used from 120 Hz up to either 800Hz or if they will go to 1.7KHz that will be better as it will cut down on the cost of the driver needed to replace the compression drivers in the Yamaha 6115H horns.

The 4520 speakers will be used from 120Hz down to their lowest frequency. The amp does have settings for a high pass so I can easily set the high pass to whatever value works best with these cabinets to keep the woofers from reproducing any frequencies that will cause the horn to unload and damage the driver.

So basically I would need to set the EQ to reduce some of the 60Hz signal? Didn't read the manual completely, but I think that Yamaha amp may have an EQ in it. If so that will make setting it very easy.

You will have to boost 60Hz down to 30Hz. You can probably cut at 25/28Hz w/ a 48db/octave filter. The bass that people will hear is around 80Hz. Easy target. The bass people will feel is under 50Hz. That takes power and many cabs.

How many 4520 do you run in that skating ring? And how much bass do you expect? What type of music do you play?

Is that the Olympia ? If so, you may need many 4520s ;-) 8 maybe. or if you're enthusiastic about getting some great thumping bass, perhaps you could build some Berthas and load them with 18" 2242 drivers. A pair of these is all you need for such a large room... and you could keep on using whatever number of 4520 you already have.

On the picture below, I iinda see a pair of 4520s placed one of top of another. Maybe I am wrong. If you want to play lower, you should put the mouth of the cabs together. So, side by side to add mouth area. Four pairs of 4520s would be great. ;-)

http://www.olympiaskate.org/uploads/...37/4719707.JPG

That isn't the one, but is in the city where I live.

They also use four JBL 4520 cabinets and they used Peavey SP-1 speakers at one point, but replaced three of the 8 with other newer Peavey speakers. Not sure how they were originally set up but back in the 80's when all 8 Peavey SP1 speakers and all four JBL 4520 bass cabs were working the sounded nice and had decent bass.

Their system is in need of work as well, but I contacted the owner a couple years ago and she wasn't interested.


The one I'm working on the sound system at can be seen here starting at 9:05 in the video https://www.youtube.com/watch?v=cbfF9ezn2mU Unfortunately they don't have any good pictures of the floor.

There are four 4520 cabinets.

Music they play is whatever is popular at the moment so mostly rap and hip hop.

I know I will not get bass down to 20Hz which is ok. Saturday when I got one of the bass cabinets working the bass from just two cabinets sounded ok, but I need to get the other two working. One measures infinite ohms on the wiring exiting the cabinet so either a wire on each speaker is disconnected or the drivers are open. The other cabinet as I mentioned in the first post caused a driver to self destruct. Suspect the other cabinets do not ave the proper drivers in them either.

The type of bass I'm looking for is more quality versus loud.

At the other skating rink one of their 4520 cabinets had two speakers in it that had CONCERT on the dust caps and it sounded pretty good in the lower bass, althoug I'm sure it didn't go down to 20Hz.

Whoever helps with their system replaced those with different drivers, although I don't know what brand and model.

I do know one cabinet may have the original or proper drivers in it and it sounds fairly good and was very natural sounding and better quality wise than most subs I've heard. Even though it doesn't go down to 20Hz what is there sounds so good. Sort of makes you forget the bass that is missing.

That I believe is the bass I'm aiming for.

I've got one more question.

Given these cabinets will be used for bass only, what is the optimum crossover frequency I should use between these and what I'm using for midbass-midrange?

I saw it mentioned where 120Hz was a good crossover point, but I forget the reasoning for that. Think it may have had something to do with the front and back waves cancelling each other out or something similar.

Also given the resonance is at 60Hz my thought is to decrease the output at 60Hz then do any necessary EQ of the lower frequencies to get as good sounding bass as possible while still being able to go loud enough without causing damage to the drivers or amp.

The amp itself is rated at 500 watts per channel into 4 ohms. Given I will be using two 8 ohm 500 watt drivers wired in parallel in each 4520 cabinet will one channel of the 500 watt amp be enough or does that mean I need an amp of 1,000 watts?

The Yamaha amp series I'm going with has the eq, crossover, delay, filters, limiter and front panel lock built in.

That will make it easy to

1. eq the cabinets
2. Provide proper crossover point between the bass cab and midrange/tweeter cab
3. Adjust the delay to time align the bass cab with the midrange/tweeter cab
4. Set a high pass filter for the 4520s so frequencies below where the horn unloads will not reach the drivers
5. Limiter will help keep the speakers from being overdriven.
6. Lock the front panel controls using a code so only authorized people can change any settings.

It also has a USB port so its settings can be saved to a thumb drive.

That way I can set up one bass cab and midrange/tweeter cab then transfer the settings to the other three amps.

Don't lower the 60Hz fundamental, raise 30-60Hz instead.

On the 4530, phase cancellation is 120Hz which is 3 times the horn lower freq. The 4530 has exceptional kick bass, but not much lower bass.
On the 4520, which is a 30Hz horn, the lower bass is much better but not much kick bass, and I suspect that phase cancellation happens at 90Hz. That's when the wave from the horn fights against the wave from the woofer. The best way to be certain is to use a calibrated microphone and REW - Room EQ Wizard (it's free).

BTW Whatever comes out of the cabinet'S mouth is 180° out of phase with the woofer.

http://www.roomeqwizard.com/