JBL 4520 question

[Tube Radio]

I got to thinking about the JBL 4520 tonight and had a couple questions. What driver was it that was recommended for the JBL 4520? I'm thinking it was a driver made by Pyle, but I cannot remember which one.Also where can I find the plans to build them if I cannot find any for purchase online at a reasonable price?

[RMC]

Hi Tube Radio,

Drivers for 4520 were not from Pyle. They were JBL, initially 2205 and later added the E140. More recently 2225 was added to the list.

There's very little official plans for these boxes. JBL probably didn't want people to copy their bass horn cabs. A number of people have nevertheless tried and did copy those with more or less success in some cases. They're not all great since its a big job.

I have 2 or 3 of this type of plans from official and reliable sources. I don't charge a dime for one, and don't push selling. But you gotta be really serious about this, i don't want to spend my time if you're just looking or thinking about those. So find the proper woofers first and when you get them then we can talk about specific plans. Regards,

Richard

P.S. I hope you do realize these are NOT subwoofer boxes, but rather sound reinforcement enclosures with some response amplitude in the bass range in oder to provide punchy bass, not very deep one.

[Tube Radio]

I seem to remember someone on the forums here a few years ago using a Pyle or Pyle Pro 15" 500 watt woofer in these cabinets and getting the same or better results as the proper JBL woofer.

[RMC]

Tube Radio,

I don't remember seeing the Pyle thread or post you refer to.

To be honest i don't hang around with Pyle and Pyramid type speakers. This is low-cost, so so quality China stuff. Plus i can't recall seeing a set of specs and T/S parameters from them, while looking at a model someone else tried without success it seemed, never mind getting a response or impedance curve for crossover purpose.

There's nothing wrong in having a low budget or wanting to save money, i can understand this. But there's a limit on how low one can go in order to get acceptable performance and tech data. When money matters there's other brands/models to consider, e.g. Peavey, Eminence, SB Acoustics, Dayton, Selenium (for what's left of it), etc. In my view, though not high-class, drivers from those manufacturers are probably better quality than Pyle & Pyramid...

Moreover, not all drivers are a proper fit for these rear-loaded folded horn, since the cavity housing the two 15" for the rear wave is pretty small. i measured it and posted before based on the plans and as i recall it was about 1.9 cu. ft. for two 15". Hence the low driver Qts for these.

Richard

[Tube Radio]

My bad I was wrong.It was a Dayton Audio woofer.Specifically this one.https://www.parts-express.com/Dayton...034?quantity=1

[1audiohack]

Hello T.R.

When you say say “same or better results”, what specifically do you mean? Better in what way?

Barry.

[Tube Radio]

The Dayton Audio driver used is found in this topic. Also the cabinet is slightly different as well so am not sure how these would work in a stock cabinet. https://www.audioheritage.org/vbulle...hlight=PA380-8That said would there be a modern currently produced JBL driver that will work good with these horns?Or maybe I should try any one of the plans for the 18" scoopers?

[1audiohack]

Hi TR

OK but what are you looking to improve? Do you want to use them as the original design intended?

2226’s are current and would work fine in them. There are others for sure. What you want to do with them is going to decide what if any driver is suitable.

Barry.

[Tube Radio]

The goal would be to have them produce whatever bass they are capable of.Now if I were to place four cabinets side by side would that be of any benefit far as the lower bass is concerned?Also would putting two upside down side by side and two on top side by side so that the horn mouths are together be any better than putting them all side by side or would it be the same?If I got the 16 ohm version I could parallel two cabs for a 4 ohm load and parallel the other two cabs and I could then use one amp.I'd use a QSC 2450A amp to power them

[RMC]

Tube Radio,

RE post # 5

I had a quick look at the Dayton PA 380 woofer and it appeared to be good value (price vs specs offered).

I compared it quickly with JBL 2225H and a number of specs are comparable or close. For $135. ($121. when buying 4) its certainly not a rip-off. Plus it seems to come with a real gasket, not those tiny tubes JBL gave or the thin cardboard molding style "gasket" i got with the 2214H (an insult, i never used).

In terms of cone travel (Xmax) the Dayton and JBL 2225 have the same capability. But the latter also has an Xlim (limit before damage) of 11 mm. This number is unknown for the Dayton. I mention this because countless woofers were abused in this type of cab, mostly used in discos and overpowered in the LF. Depending on your intended use, i would be somewhat prudent about beating the crap out of them.

Dayton probably saved on cost by having them made in China (like all the rest), and not having a cast frame. The stamped frame used shows having a number of reinforcements for rigidity and preventing warping, so that's ok. Nonetheless they seem to be well made for the price tag.

Not the dream LF driver, but for $121. each to load your cabs with acceptable woofers i'd say its a good deal.

Richard

[Tube Radio]

I suspect many discos used the bare minimum they could get by with and get acceptable sound when had they used more, they would have gotten better sound and not had to run them so hard.Also I suspect many didn't use a high pass at the frequency the horns unloaded at and maybe even boosted the lower bass to try and make the lower bass be reproduced which would have done damage. Now where I would be using these is at a skating rink with 10,000 square foot floor with each corner having a curved wall. If I place one or two cabs per corner where the cab is flush with the wall, what effect on the bass would the curved wall have?However, I asked about the four currently in use subs (Yorkville ls-1208) on another forum and it was suggested to try them in a different position in rhe rink so I'll do that first before going with these. Now OAP makes a nice single 18 W bin that when used in multiples can go below 40Hz so if the Yorkvilles cannot do what is needed perhaps the 4520s for now and adding the OAP later on for under 40Hz reproduction.

[short_circutz2]

We had to replace the subwoofer/lf section of the house pa at the club I teched at. We scored on 8x Martin 115 bins. When we got them, they were loaded with a mixture of 15" drivers, mostly 2225. They had been used previously without a high pass filter, and as a result, I had toreplace several cloth surrounds on a few of the 2225 units.

After doing some research, the most economical North American replacement had the Eminence Kappa Pro 15lf listed, so thats what we reloaded 6 of them with, and never had a failure (also had them hi-passed thru the Driverack PA). 3 cabs per side was all that was needed for the room and gave enough spl to feel my pant legs tickling my legs at the mix position.

Was funny to see the ocassional band engineer trying to get the kick sound they were looking for, because they werent used to the sound of a horn loaded bass system.

[Tube Radio]

The 4520s at the other rink in town produced the most natural sounding bass I've ever heard. I'll look up the Martin 115 as well and see if that would be a viable option. Therein is the thing.Even though the yorkvilles are horn loaded, the bass doesn't sound nearly as natural as the 4520s.

[Tube Radio]

Someone on a vintage audio group on Facebook has two JBL W bins each with a 18" driver.Would those work better in this application provided I can find some or plans to build them?

[Riley Casey]

It would be good to describe exactly what your application is. Large folded bass horns are a relic of the days when high powered amplifiers delivered 100 watts to speakers that barely survived 60 watts. They made a great many compromises to achieve maximum output with minimal electrical input. While the W18 has a 40 hz flair rate the mouth area is a quarter of what's needed to support full 40hz horn performance so yes four W18s in a stack will give you fairly good performance for a folded horn if you really need 40hz. Certainly better than a big stack of 4520s but... A lot has changed since the days when these horns were designed. Modern power amps and drivers in vented boxes make for a much more powerful and reliable bass reproducer if indeed you're installing these in a roller rink. Unless of course the whole point is to have a 'vintage' sound system in which case forget everything I said. That said however I'd think that an emphasis of 40 hz performance is misplaced. Vintage sound systems didn't produce much 40 hz, vintage recordings didn't contain much 40 hz at least in the music you'd likely play at a roller rink.

Someone on a vintage audio group on Facebook has two JBL W bins each with a 18" driver.Would those work better in this application provided I can find some or plans to build them?