Oh no. I did it. JBL 4520 related

[Lee in Montreal]

Will be renting a van next week to pick-up a pair of 4520. Current owner has 8 of them. He keeps 4 to himself and I get a pair. One pair up for grab, Eaulive...

They are empty and dirt cheap. Only catch is that they were painted white as they got rented for a movie that pictured the early 1980s disco era. Movie is called "Funkytown". I will load the 4520s with the 2225h I already have.

They can be seen here.

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[Eaulive]

I' going there at 5.... damn clock is so slow.....

[Eaulive]

Argh, delays, traffic, rush hour, guy still at work.
Going there later.

[Lee in Montreal]

I made some quick calculations.

The 4530 had a 7ft scoop - meaning 43Hz resonance at 1/4 wave
The 4520 is 12ft scoop - meaning 25Hz at 1/4 wave. And a mouth that is more than twice as big.

25Hz resonance would be a waste with drivers such as a 2225h which has Fs 40Hz and dies at 30Hz. I am not looking for sound pressure as the 4520s will be in my basement. I have four good 2225h currently in use and four 2225h baskets. Thinking reconing the 2225h baskets as 2235h with Fs 20Hz. It could be interesting. The 2245h I already have will be in a separate sub "to fill holes".


Hmm... Or maybe not. If indeed the 4530 is tuned to 25Hz and that the 2235 has a lower Fs, I will end up with excursion problems, pretty early. Damn.

[Eaulive]

The 4520 is useable down to 30Hz, below this the woofer is unloaded and will get damaged, unless you keep it at low levels. Of course, with this kind of hardware "low" is relative :D

[Ruediger]

...
The 4530 had a 7ft scoop - meaning 43Hz resonance at 1/4 wave
The 4520 is 12ft scoop - meaning 25Hz at 1/4 wave. ...


I know that these are the "official" values for the horn length, but I could not verify them. Get some construction plans and check Yourself.

The frequency response plotted in the 4520 brochure seems realistic to me. The 2225 seems to be a good driver for these horns. The 2235 would be killed in a minute.

Where are You going to place them? How big is the room?

Ruediger

[Eaulive]

Here they are...
50388

[Lee in Montreal]

Here they are...
50388


Ah, ah. Eaulive did it too. :D
In fact we are sharing the four remaining 4520s. I will pick mine up next week.
$200 a pair including speaker clamps is a good price... And they are now famous after showing up in a disco movie. :eek:

They will do the job until I build some modified versions with twin 18" drivers. Not Waldorf yet but taller than stock.

[Lee in Montreal]

Official JBL litterature claims a 13ft path for the 4520 vs 7ft for the 4530.

http://www.jblpro.com/pub/obsolete/low_frequency_enclosures2.pdf

I have a hard time understanding how it could be close to twice as long however I measure it. But Eaulive did gave measures of the respective mouths in a previous thread. 5650cm2 vs 3078cm2 and I think this is where the huge difference in tuning frequency comes from. The larger the mouth, the lower the resonance.

Mouth size and path length. Looking at Bertha's (simple W bins) with the Levan extension, it seems it makes sense. But don't worry. I have no intention to install Berthas in my basemement unless I want to end my couple. :D But damn wouldn't it be great to load them with two 2242... That sure would piss off all neighboors within a block.

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[Lee in Montreal]

Si I met Eaulive this afternoon while he was picking his set of 4520s. I have put my name on a set for myself. Eaulive went thru a dozen of K130 2220A and 2205A to test them. I will be going back to pick up my bins next week after I clear my garage (there's a racecar on jackstand in there). I will perhaps be selling my 4530s to Eaulive's friend. Therefore the number of enclosures will not be changing in my listening room as I am replacing a pair of 4530s for a pair of 4520s. I'm safe, my GF can't say a thing... ;)

Lee

[Eaulive]

Si I met Eaulive this afternoon while he was picking his set of 4520s. I have put my name on a set for myself. Eaulive went thru a dozen of K130 2220A and 2205A to test them. I will be going back to pick up my bins next week after I clear my garage (there's a racecar on jackstand in there). I will perhaps be selling my 4530s to Eaulive's friend. Therefore the number of enclosures will not be changing in my listening room as I am replacing a pair of 4530s for a pair of 4520s. I'm safe, my GF can't say a thing... ;)

Lee

Nice to meet you this afternoon Lee.
Yes, the speakers I tested didn't convince me so much. There was six 2205A, one K130, one K140, one 2231A and seven 2220A if I remember well, all reconed as 2225 except one 2205A that was having the original cone.

I tested the six 2205A with a pink noise and only two were matched in sound, all the others were sounding different... I won't be buying any of them :eek:

I just checked Lee, the 2231A seems to be the ancester on the 2234/5, a HIFI driver, rolled surround, same magnet and coil as a 2225 but heavier cone (almost as heavy as the 2235)

[Lee in Montreal]

Currently looking at ways to position the 4520s in my listening room. I was thinking laying them flat on their side, drivers on the outside, and mouths together (bottom to bottom), in order to double mouth perimeter from 32.75" x 26.75" = 10ft to 20ft in twin configuration.

So by doubling the mouth perimeter, by how many Hertz can a lower the cut-off? My understanding is that 20ft perimeter is 28Hz at 1/2 wavelength.

[jcrobso]

Here they are...
50388
The pair of 4520s that I used for the Church installation had 2226 in them.
The low bass was effortless, but I put most of my budget into speakers so I ended up using a PL700 to drive them. I figured I would upgrade the amp later but never felt the need to do so.
Soon after the system was setup in the Church we did a kids program based on the Indiana Jones theme. There was an earthquake scene in the program and the sound track had an earthquake sound for about 30 seconds. Little did anyone realize what was about to happen. The kids had been practicing to a boom box and had been instructed to just jump around when they heard the quake sound.
On performance day I added 15db of boost at 80hz from the mixer channel and opened up the channel to full gain,,, and the whole room shook!!!!;) The kids didn't have to jump around as the stage was shaking, the people were shaking in the pews.:bouncy:
Everyone loved it, so I got to keep my job.:blink:

[Ruediger]

Currently looking at ways to position the 4520s in my listening room. I was thinking laying them flat on their side, drivers on the outside, and mouths together (bottom to bottom), in order to double mouth perimeter from 32.75" x 26.75" = 10ft to 20ft in twin configuration.

So by doubling the mouth perimeter, by how many Hertz can a lower the cut-off? My understanding is that 20ft perimeter is 28Hz at 1/2 wavelength.

You're assuming the wrong "physics". Get Yourself either "Acoustics" from Beranek or "Acoustical Engineering" from Olson. A book which gives You an idea of how horns work, and that without mathematics (!), is "Hi-Fi Loudspeakers and Enclosures" from Cohen.

Ruediger

[Lee in Montreal]

You're assuming the wrong "physics".

Well, please explain, because PA guys do just that to lower the "reach" of their bass bins. ;)
Not to mention that any exercise in horn design goes thru the mouth perimeter to define cut-off frequency.

[macaroonie]

I'm not going to tell the old ' wide mouth toad ' joke here but Lee I am looking forward to seeing your Smiffy throats.
Good score on the bins though . cheaper than the plywood alone and with Mojo built in :applaud:

[Ruediger]

Well, please explain, because PA guys do just that to lower the "reach" of their bass bins. ;)
Not to mention that any exercise in horn design goes thru the mouth perimeter to define cut-off frequency.

The flare defines the cutoff frequency, and the perimeter together with the length determines the ripple. In the books I recommended there are plots which show that in much detail (book 1 and 2).

If You place the 4520 in the corner of a room (1/8 space) then the mouth area is sufficient anyway. If You want to gain something by placement or combining then corner placement is the most effective.

Ruediger

[Eaulive]

Me and my friend helped Lee bring home his new babies (4520) this morning and my friend took posession of Lee's 4530s.

We hooked them up this afternoon and rediscovered with pleasure the extra tight JBL bass :applaud:

I'm off now, got to prepare sand and paint my old 2370 horns.

[Lee in Montreal]

Picked mine this morning with Eaulive and Stéphane. Out went the 4530s and in came the 4520s. Spent a few hours sanding and fixing on of the 4520s. Now the paint is drying in my basement. Those things are huge compared to a 4530. . 7" taller, 6" deeper, 12" wider.

50536

[maxwedge]

You're not going to be able to play a record when you have those 4520's powered up!:p
I have always like those cabinets but have never owned any.:dont-know:

[John]

Picked mine this morning with Eaulive and Stéphane. Out went the 4530s and in came the 4520s. Spent a few hours sanding and fixing on of the 4520s. Now the paint is drying in my basement. Those things are huge compared to a 4530. . 7" taller, 6" deeper, 12" wider.

50536

I was kind of digging them in White!!! :(

Oh well "back in black":cheers:

[Eaulive]

Picked mine this morning with Eaulive and Stéphane. Out went the 4530s and in came the 4520s. Spent a few hours sanding and fixing on of the 4520s. Now the paint is drying in my basement. Those things are huge compared to a 4530. . 7" taller, 6" deeper, 12" wider.

50536

Man, you don't lose time! :applaud:

[Eaulive]

I'm off now, got to prepare sand and paint my old 2370 horns.

Nice :D
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[Lee in Montreal]

Nice horn.
Nice sticker. :bouncy:

[Lee in Montreal]

We hooked them up this afternoon and rediscovered with pleasure the extra tight JBL bass :applaud:

Yup. The 4530s have a very tight bass, which is not present in the 4520s. Similar design. Different sound.

[Eaulive]

Yup. The 4530s have a very tight bass, which is not present in the 4520s. Similar design. Different sound.

No? please explain, more bass extension but less punch?

[Lee in Montreal]

More bass extension. Way more. Less upper bass and less kick.

Here they are now. Installed. I am a happy camper. Until I build a set of modified 4520 for 18" 2240h drivers which go 10Hz lower and shall be a perfect/better match for the 4520 :eek:

On the opposite wall, I have a 2245h sub crossed over at 50Hz.

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[Eaulive]

More bass extension. Way more. Less upper bass and less kick.

Here they are now. Installed. I am a happy camper. Until I build a set of modified 4520 for 18" 2240h drivers which go 10Hz lower and shall be a perfect/better match for the 4520 :eek:

On the opposite wall, I have a 2245h sub crossed over at 50Hz.

50596

Wow, this is better than pr0n :bouncy:

Mine won't be finished before next week, and my four C8R2225 are in transit somewhere between Northridge and here :drive:

[Lee in Montreal]

One trick: bolt some casters underneath. They will make your life easier. Loaded, the 4520s are close to 280lbs each

[Lee in Montreal]

Received a pair of 2350 and 2397 adapters this afternoon. I made a quick draft and made a pair of adapters to fit some... 104h-2. Currently with open back, but soon with a deep salad bowl as a rear baffle. The result is surprisingly good.

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[macaroonie]

Lee are you doing anything WRT time alignment. Also I notice that for exmple you had the 2405 way bck on top of a flt surface. Probably not a good thing. Other than that you are a nutter

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[Lee in Montreal]

I have since revised the position and located the 2405 as far back as possible, barely ahead of the medium driver. I will close the back of the medium driver tomorrow. I bought some 6" Sonotube and will make a round sealed enclosure. Probably around 9" deep.

BTW I love the sound of a cone driver mated to a long horn. The L104H- rolls off at 7k, where it is crossed over with the 2405. Great match. And the horns gives it some efficiency and projection. Unusual combo, I know, but it works, while the driver is cheap. ;)

[Lee in Montreal]

I have been redesigning the 4520 enclosure to accept a pair of 18" drivers. I'd like to regain the tightness of the 4530 which is lost in the 4520, while reaching 15-20 Hz lower.

I checked out the 18" e155 bass instrument speaker. It has an Fs 30Hz (which I expect the new 4520 to be tuned to, and a Qts 0.2 which promises tight bass. What are you thoughts?

[Lee in Montreal]

Tonight, I removed all four 2225 drivers to inspect them closely. From the front, the cones and suspension have 100% the same texture, glue colour, and glue spread. The felts all around the basket are also 100% identical. It is when I turned them on their face to inspect the back of the cones that the differences became clear.

The good sounding drivers had "2225h" written in big white letters, and a smallish white round "JBL Pro" tag. Not so on the two bad sounding ones. Different textures on the back of the cone, no script, no tag. Gonna have to have a chat with that dude who sold them... ;)

So, I guess it does explain why one 4520 sounded good, and the other was anemic.

[Eaulive]

Tonight, I removed all four 2225 drivers to inspect them closely. From the front, the cones and suspension have 100% the same texture, glue colour, and glue spread. The felts all around the basket are also 100% identical. It is when I turned them on their face to inspect the back of the cones that the differences became clear.

The good sounding drivers had "2225h" written in big white letters, and a smallish white round "JBL Pro" tag. Not so on the two bad sounding ones. Different textures on the back of the cone, no script, no tag. Gonna have to have a chat with that dude who sold them... ;)

So, I guess it does explain why one 4520 sounded good, and the other was anemic.

They maybe not original cones :banghead:

[Lee in Montreal]

They maybe not original cones :banghead:

Definitely aftermarket recones of the most inferior quality soundwise.

[subwoof]

the only way to "tune" a folded horn lower is to make it longer - for your goal, a LOT longer. Unlikely you would be able to fit it through any door. The Fs of the driver is mostly irrelevant unless it unloads easily ( ex: 2235 ) when given a signal below the horn's cutoff.

Physics doesn't change.

[more10]

If you use 2 horns together, placed side by side, they should output a bit more energy in the lower end due to larger exit area.

[Lee in Montreal]

If you use 2 horns together, placed side by side, they should output a bit more energy in the lower end due to larger exit area.

Yes. My thoughts too. For now, I will replace the two akward 2225h with a good pair and keep them that way until I build a pair of cabinets that can house two 2440 each.

[Eaulive]

the two akward 2225h

What did the seller had to say about this?

[Lee in Montreal]

Ben busy lately. BUt I am purchasing either a NOS C8R2225 and a freshly reconed 2225h, or two god used 2225h with JBL cones. Waiting for prices. Then this summer I will build the 4520s for 18" 2240h drivers. Found a place in the US where they have them for $125 a piece with recent original JBL recones.

Lee

[Eaulive]

Ben busy lately. BUt I am purchasing either a NOS C8R2225 and a freshly reconed 2225h, or two god used 2225h with JBL cones. Waiting for prices. Then this summer I will build the 4520s for 18" 2240h drivers. Found a place in the US where they have them for $125 a piece with recent original JBL recones.

Lee

Good prices, if they are original.
Let me know if you want to sell your two "bad" 2225s

[Lee in Montreal]

Let me know if you want to sell your two "bad" 2225s

You'll be the first to know. I'll wait until I receive the other drivers.

Actually, I even thought for a moment they might have been 2227 recones in the 2225. The 2225 is known for its superior bottom end. No wonder the 2227 is a mid bass driver rated at 50% extra power if it lacks real 10Hz "down there"...

[1audiohack]

2227 kits will no way in hell work in 2225 baskets.

[Eaulive]

2227 kits will no way in hell work in 2225 baskets.

Don't think so either, VC won't fit in the gap.

[Lee in Montreal]

Don't think so either, VC won't fit in the gap.

So it must be something else that fits in but doesn't sound right. :D

[more10]

Then this summer I will build the 4520s for 18" 2240h drivers.

Why don't you build new Rog Mogale 18" cabinets (http://www.speakerplans.com/index.php?id=18superscooper) instead of modifying the 4520s?

PD1850 (http://www.precision-devices.com/ShowDetails.asp?id=15):
THIELE SMALL PARAMETERS
Fs 30 Hz
Re 5.4 Ohms
Qts 0.21
Qms 6.04
Qes 0.22
Vas 249 Litres
Mms 216.4 g
Sd 1150 cm2
Cms 133 μM/N
BL 31.57 T/m
Xmax 11.05 mm
Vd 1.271 Litres
Reference Effi ciency 2.88 %

2240HG (http://www.jblpro.com/pub/obsolete/2240.pdf):
Thiele-Small Parameters:
fs: 30 Hz
Re: 6.0 ohms (H); 2.5 ohms (G)
Qts: 0.23
Oms: 2.2
Qes: 0.25
Vas: 480 I (I7 ft’)
SD: 0.130 m2 (200 in’)
X max: 5.5 mm (0.22 in)
VD: 720 cm? (44 in?)
Le: I.4 mH (H); .65 mH (C)
q. (Half space): 5.0%
Pe(Max): 300 W Continuous Sine Wave

They differ in Qms and Vas. I have no idea if it is going to work well.

[Lee in Montreal]

Why don't you build new Rog Mogale 18" cabinets (http://www.speakerplans.com/index.php?id=18superscooper) instead of modifying the 4520s?

Because the Superscooper is a modified 4530 (single driver) and I am using two drivers per enclosure (4520).The 4520 and 4530 sound very differently. One is a kick bin (4530) while the other goes deeper (4520).

The Superscooper has a 2.22m pathway, while the 4520 I redesigned has 2.57m, and a lot more volume. Longer pathway and extra volume = deeper bass.

If I made the enclosure 4" taller, I could increase the pathway by 11" and reach 30Hz.

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[Ruediger]

Because the Superscooper is a modified 4530 (single driver) and I am using two drivers per enclosure (4520).The 4520 and 4530 sound very differently. One is a kick bin (4530) while the other goes deeper (4520).

The Superscooper has a 2.22m pathway, while the 4520 I redesigned has 2.57m, and a lot more volume. Longer pathway and extra volume = deeper bass.

50794

1.) You may scale the 4530 linearly by multiplying height and depth coordinates with a constant factor.

2.) Why not build 4 single scoops instead of 2 double scoops? Would be easier to transport.

3.) Have a look at
http://www.audioheritage.org/vbulletin/showthread.php?3765-Question-on-the-quot-double-scoop-quot-short-throw-horn.&p=76500&viewfull=1

ruediger

[Lee in Montreal]

I will read the whole thread tonight. But something tells me I am heading in the right direction.

http://www.audioheritage.org/vbulletin/showthread.php?3765-Question-on-the-quot-double-scoop-quot-short-throw-horn.&p=34779&viewfull=1#post34779

"Originally the E-155-8 is what we used in our upsized JBL copies! They were great, the punch, the bass articualtion, and fast transient snap were fantastic! But wasnt the greatest deep bass! The 2240 makes better deeper bottom!..."

"On an RTA I have usable response down to 30Hz, it actually is flat down to 30, and I can squeeze some response to 25hz..."

[Lee in Montreal]

I have quickly redesigned and simplified the AJ Design principle (adding one baffle to extend the pathway) that was mentionned in that old thread. The bin has the same height and depth as a stock 4520, only a few inches wider to accomodate a pair of 18" drivers in replacement of the original 15".

There not much to change as it is. It is tuned to the 2240h's Fs 30hz.

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[Eaulive]

Yes , I saw this design also but the LF cutoff is determined by the mouth area if I'm not mistaken so no gain here.

[Lee in Montreal]

Yes , I saw this design also but the LF cutoff is determined by the mouth area if I'm not mistaken so no gain here.

If the cut off was only determined by the mouth, then I would probably simply cut a big square hole in a 4'x8' and place a woofer behind... :D Just kidding.

Transmision lines speaker and tapped horns are closely related to the length of the pathway, which is what determnes the resonance. I might be wrong, but isn't mouth size only one of the elements that determine how low the cabinet can go?

[Eaulive]

If the cut off was only determined by the mouth, then I would probably simply cut a big square hole in a 4'x8' and place a woofer behind... :D Just kidding.

Transmision lines speaker and tapped horns are closely related to the length of the pathway, which is what determnes the resonance. I might be wrong, but isn't mouth size only one of the elements that determine how low the cabinet can go?

I think it's one of the elements, yes, not the only one probably, but nevertheless, if one of the elements limits the cutoff, there's no point in optimizing the others to go lower.

That's my understanding, I may be wrong. :)

[Lee in Montreal]

Some horn principles call for the mouth circumference being the length (or period) of the lowest wave length reproduced. The mouth above is .95m x .69m or 3.28m in circumference.

According to the principle previously mentionned, this should be good for 104hz... I understand that 4520s go much lower than that. Therefore I suspect that the principle that works for midrange horns might not apply necessarely to a bass horn as otherwise 30Hz, would require a 10.5 square meter mouth according to this other calculation.

SL = (c / (2 fc))2 / π

C is speed of sound
Fc is frequency cut-off
π is 3.1415.....

[1audiohack]

[QUOTE=Lee in Montreal;310474]Some horn principles call for the mouth circumference being the length (or period) of the lowest wave length reproduced. [QUOTE]

One wave length if operated in free space, sat on a plane you get to halve the mouth arra as the boundary is seen by the driver/horn assembly as another like unit, pushed up to a side wall and you get to halve the mouth area again. The type of unit you are building does not lend itself to eighth space loading so the party ends at 1/4 space, 25% mouth area.

[Lee in Montreal]

The type of unit you are building does not lend itself to eighth space loading so the party ends at 1/4 space, 25% mouth area.

If indeed the principle to follow is that the circumference shall be 1/4 wavelength of the lowest frequency, then 3.28 meters (the throat perimeter) is good for 26Hz. Good enough for a pair of 2240 woofers with Fs = 30Hz and a pathway tuned to 29Hz (maybe 30Hz).

[Lee in Montreal]

For those with no space limitation, i found that Gary Stewart Audio is making what looks like his own brew of Waldorf. Talk about a big mouth... ;) They seem to be based on the JA Horn with the extra vertical baffle.

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And a single driver version

50810

[Eaulive]

Big! :blink:

[Lee in Montreal]

Looking at the third picture, I can see some writing on the walls. "Sortie", "Entrée". I guess the cabinets and drivers must have been assembled in Montreal for a local bar. "Stereo" in Montreal had 8 of them, standing on Berthas with Levan horns. But that bar was set-up by SystemByShorty, not GSA. I wonder what bar has those tall cabinets in Montreal...

[Ruediger]

Some horn principles call for the mouth circumference being the length (or period) of the lowest wave length reproduced. The mouth above is .95m x .69m or 3.28m in circumference.


The recommendation that the mouth circumference should be one wavelength is meant for a circular mouth of equivalent area.

ruediger

[Eaulive]

Looking at the third picture, I can see some writing on the walls. "Sortie", "Entrée". I guess the cabinets and drivers must have been assembled in Montreal for a local bar. "Stereo" in Montreal had 8 of them, standing on Berthas with Levan horns. But that bar was set-up by SystemByShorty, not GSA. I wonder what bar has those tall cabinets in Montreal...

Good eye, is that company local?

[Eaulive]

Nope, I just googled them...Las Vegas.
http://www.gsany.com/

[Lee in Montreal]

Good eye, is that company local?

GSA is from NY, but cabinets and drivers must have been assembled in Québec for a local bar.

And they are definitely not the ones at "Stereo". They had regular 4520s and Berthas with Levan extensions.

http://www.systemsbyshorty.com/sbsstereo1.swf

And found this interesting thread with Shorty himself.
http://www.wavemusic.com/community/showthread.php?p=45333

[Eaulive]

On the last pictures, I don't recognize the city, and it's definitely not Montreal!
Unless the mountain vanished....

[JBL 4645]

Picked mine this morning with Eaulive and Stéphane. Out went the 4530s and in came the 4520s. Spent a few hours sanding and fixing on of the 4520s. Now the paint is drying in my basement. Those things are huge compared to a 4530. . 7" taller, 6" deeper, 12" wider.

50536

:applaud: :bouncy: Nice set-up! What Behringer EQ model is that?

[Lee in Montreal]

:applaud: :bouncy: Nice set-up! What Behringer EQ model is that?

This one is a CX3400 and love it. I also have a DCX2496.

[JBL 4645]

This one is a CX3400 and love it. I also have a DCX2496.

I noticed the DCX2496 in the other post. It’s a logical choice. I like watching the funky LED’s on mine moving up and down. Have fun with yours. ;):)




Mouth size and path length. Looking at Bertha's (simple W bins) with the Levan extension, it seems it makes sense. But don't worry. I have no intention to install Berthas in my basemement unless I want to end my couple. :D But damn wouldn't it be great to load them with two 2242... That sure would piss off all neighboors within a block.

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What are planning to do play Earthquake! You’d piss me off if that was playing below me LOL:p

[Lee in Montreal]

The AJ Horn plan and the pictures from the GSA/RLA cabinets make total sense. They found the way to make the path much longer than stock 10' vs 8', even in standard height. Looks like standard 4' height gives you a reasonable 27Hz, while to achieve under 25Hz, the cabinet must definitely be much taller to accomodate a bigger mouth and longer path. I guess I will settle with 27Hz. ;)

50820

[Lee in Montreal]

Found some interesting reading.

http://www.ibiza-voice.com/media/news/News/larry_levan/sound.html

"The first part of the new system consisted of 4 "Waldorf" bass speakers. First used in a rental at the Waldorf Astoria, it is similar to the JBL double 15" scoop enclosure but is based on the old Jensen Imperial design. The enclosure was made larger to accommodate a larger rear loaded horn, which was designed with a hyperbolic rather than an exponential flare. The high end consisted of the largest JBL horn lens for smooth wide dispersion and the system is electronically crossed over at 80hrz These replaced the corner home-type speakers."

Leading me to that http://www.decware.com/imperial.htm
"High Fidelity Playback - As shown above with special considerations or with a single 15 inch coax, using the 2nd woofer for 50 Hz and below."

Basically, despite the ressemblance with a 4520, the Waldorf, as designed by Richard Long, is an "adapted" Jensen Imperial. I still wonder how they made the cabinet go down in frequency if the tunnel is that short. BTW GSA's cabinets seem to be the same as RLA's as he was transfered the technology after Ricjard Long passed away. From the pictures I posted a bit earlier, the front view shows a deep recess behind the drivers, and the upper "ducts" as on the Jensen Imperial.


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[more10]

[QUOTE=Lee in Montreal;310387Then this summer I will build the 4520s for 18" 2240h drivers. Found a place in the US where they have them for $125 a piece with recent original JBL recones.
Lee[/QUOTE]

You can do other fun stuff with 2240: Diy 80hz mid-bass horn... drums never sounded so good! (http://inlowsound.weebly.com/diy-80hz-mid-bass-horn.html)

[Lee in Montreal]

You can do other fun stuff with 2240: Diy 80hz mid-bass horn... drums never sounded so good! (http://inlowsound.weebly.com/diy-80hz-mid-bass-horn.html)

I am close to finishing the design of the cabinets. Unlike the Waldorfs which seem to have a large back chamber (which is supposedly good for round bass), I am electing to use a small back chamber to promote compression and efficiency. The goal is to have a tight/fast bass (like a 4530) but down to 30Hz. The cabinet will be 5' tall and 30" deep. Still manageable at home.

50923

[Ruediger]

...
I am electing to use a small back chamber to promote compression and efficiency. The goal is to have a tight/fast bass (like a 4530) but down to 30Hz.
...

The backchamber acts as a low pass filter at the entrance to the horn. At, say, 150Hz+ it shall prevent sound waves from entering the horn, as that would lead to destructive interference together with the sound radiated from the front of the speaker.

ruediger

[Lee in Montreal]

According to DB Keele, one of the way to calculate the back chamber in a rear horn loaded bass cabinet is the formula below. It is one of the ways as not everyone seems to agree.
http://www.rocketsciencecanada.com/RocketScienceCanada/images/Sound/backvolform2.gif

VB is the back volume (volume of compression chamber)
ST is the throat area of the horn (590cm2)
FC is the horn cutoff frequency (30Hz in my case)
c is the velocity of sound (344m/s)

My calculations tell me I need 0.1076m3 volume. The volume can be reduced by lowering the thoat area, or raising the cut-off frequency.

[Ruediger]

http://www.rocketsciencecanada.com/RocketScienceCanada/images/Sound/backvolform2.gif

That is equation 14 from the Keele paper. It is about front loaded horns, not about rear loaded ones, or am I missing something?

Ruediger

[Lee in Montreal]

That is equation 14 from the Keele paper. It is about front loaded horns, not about rear loaded ones, or am I missing something?

Ruediger

I will check further. From memory it was for rear loaded horn, but I might be wrong. Being wrong is part of the explorative process :bouncy:

[Ruediger]

What You need is equation 24 in the Keele paper. The back chamber in the Keele paper is for reactance annulling - You don't have that. The front cavity in the Keele paper is Your back chamber.

Fhc = 2 * Qts * Fs * Vas / Vfc

Vfc = 2 * Qts * Fs * Vas / Fhc

For the 2225H and 150 Hz this yields 25 liters. Sounds okay.

Make a plot of the phase of sound from horn mouth and from front of diaphragm. then determine cutoff frequency, and thus chamber volume.

ruediger

[Lee in Montreal]

THanks very much. BTW I will use two 2240h. The 2225h barely reach 30Hz while the 2240 have Fs 30Hz.

[Ruediger]

THanks very much. BTW I will use two 2240h. The 2225h barely reach 30Hz while the 2240 have Fs 30Hz.

Driver resonance frequency is almost irrelevant. You should really have a look at the books I recommended in the past. The Keele paper tells You the Flc for a non-short horn. What You build is a short horn with resonances.

ruediger

[Ruediger]

Found an old article in two parts. Part 1 contains the plots which I meant.

See page 2 in part 1. The exponential horn and the hyperbolic horn have no useful radiation resistance at "cutoff". Above cutoff the hyperbolic horn has a high resistance, and the exponential horn has a low resistance.

See page 4 in part 1. The locations of the resonance peaks are determined by horn length. The magnitude of the peaks is determined by horn mouth area.

ruediger

[Lee in Montreal]

Thanks. That's some long reading for the weekend. :D

Lee

[Eaulive]

Yeah, I will let you guys design it, if it sounds good I'll build it :D

[Lee in Montreal]

Found a nice calculator to shape the horn's progression.

It does exponential and hyperbolic. The 4520 is exponential while the Waldorf is hyperbolic, which is a strange decision as, according to some reading, hyperbolic horns are rone to distorsion.

http://fullrangedriver.com/singledriver/exphypcalc.html

[Eaulive]

Look at this: http://www.flickr.com/photos/blowin/sets/72157626354448104/detail/

Looks like modified 4530s, with an 18" driver

[Lee in Montreal]

Look at this: http://www.flickr.com/photos/blowin/sets/72157626354448104/detail/

Looks like modified 4530s, with an 18" driver

...And a small mouth.

To make a modified 4520 go lower, one needs a longer horn and bigger mouth. For the mouth, there's no substitute to two side-side drivers like a 4520, but even taller. I am still working on it ;)

Thanks for the link.

[Eaulive]

Give us some news, how do you like them?
How about those "wrong" 2225Hs?

[Lee in Montreal]

Here's a little follow-up to the 4520 thread. My fetish is with Yamaha power amps, especially the late 1970s P2200 serie, and mid 1980s PC2002 serie. 230wpc workhorse that were used to crank dancefloors as well as monitoring studios.

I already have 5 of them and while browsing Kijiji late at night, I found a decent set of PC2002 (230wpc) and PC1002 (100wpc) for the price of one core. Both came from an ice rink and were never rack mounted. I spent $200cad for the pair and 1 hour of my day dedusting them and removing stains from 30 years of exposure to nicotine. The only mark is remaining glue from the original installer sticker.

I have now two identical PC2002 and each one will power each 2225h in the 4520. I will use the PC1002 to power my pair of 2441.

52811
52812
52813

[Eaulive]

Nice catch.

BTW, I will be ready for your yammies soon. I'm moving this weekend and my workshop will be up and running next week. :D


240W?
that's not enough for the 2225, I give them 450W out of two Crown XS700 :applaud:

I Like vintage speakers but recent amplifiers. Better technology, more silent, stable, powerful, light, small.
And they don't burn and take your valuable drivers with them. However I have to admit the XS series is one of the worst ever made by Crown. I have 6 of them, they were replaced by Crown in 2006 free of charge for the newer XTi series when those XS started to actup at a customer install in Punta-Cana.
They didn't even bother to claim them back.

I fixed them so they work, but they're not the most reliable thing, I wouldn't sell them to my ennemy :crying:

[reVintage]

This is what to expect in 1,0*Pi with a chamber volume of 80dm3.

[Lee in Montreal]

240W?
that's not enough for the 2225, I give them 450W out of two Crown XS700 :applaud:

Back in the days,the 4520s were powered by 150wpc Crown D300 :D
I don't play them at a high volume anyway, and if I need more juice, the amps can be bridged to 700w. Basically all I'd need is to find another pair of PC2002s...

[reVintage]

This is Imperial/K130 in 1,0*Pi.
At the bottom 1*2240/Imperial 1,0*Pi.

[Eaulive]

Back in the days,the 4520s were powered by 150wpc Crown D300 :D

You mean like this :applaud:
52821

This was my first system back in 1987, see the resemblance? :D
Those were not real 4520s, there were 24" deep and the horn was a lot shorter, loaded with cheap addison 15"
The midbass was an early attempt to a horn and the HF section was a lot of cheap tweeters stuck together.
I had a home made fixed electronic crossover, if I remember well it was 150 and 1500 Hz, the Crown DC 300 for the 4520s, a Sansui 100W for the mid and a homemade 40W amp for the highs.
I thought it sounded good at the time, that's why 20 years later I'm at it again :D

[Lee in Montreal]

Hi Olive

Start finding sources for some 2SC2608 and 2SA1117 output transistors for my new PC2002 as I suspect some of those are in bad shape or burned. Volume is much lower than my other PC2002, and both chanels aren't equal. :(

[Eaulive]

Roger that

[Lee in Montreal]

Not 100% sure, but I may have found the reason for the low output. I tried using the jacks and the sound was of the proper level. I then inquired on another forum and was told to check the pin selection switch when using the XLRs, as selecting the wrong set-up will only get you the signal from the crosstalk... ;)

[djmike]

Hi Lee -

Have you built this yet?

Mike


Found some interesting reading.

http://www.ibiza-voice.com/media/news/News/larry_levan/sound.html

"The first part of the new system consisted of 4 "Waldorf" bass speakers. First used in a rental at the Waldorf Astoria, it is similar to the JBL double 15" scoop enclosure but is based on the old Jensen Imperial design. The enclosure was made larger to accommodate a larger rear loaded horn, which was designed with a hyperbolic rather than an exponential flare. The high end consisted of the largest JBL horn lens for smooth wide dispersion and the system is electronically crossed over at 80hrz These replaced the corner home-type speakers."

Leading me to that http://www.decware.com/imperial.htm
"High Fidelity Playback - As shown above with special considerations or with a single 15 inch coax, using the 2nd woofer for 50 Hz and below."

Basically, despite the ressemblance with a 4520, the Waldorf, as designed by Richard Long, is an "adapted" Jensen Imperial. I still wonder how they made the cabinet go down in frequency if the tunnel is that short. BTW GSA's cabinets seem to be the same as RLA's as he was transfered the technology after Ricjard Long passed away. From the pictures I posted a bit earlier, the front view shows a deep recess behind the drivers, and the upper "ducts" as on the Jensen Imperial.


50842

[Lee in Montreal]

I am still holding on it. The drafts are done for twin 18" drivers. Progresion curve is nice but I am a bit puzzled by how short the horn is as it is tuned to 40Hz with a mouth that is able to handle much lower. I still have to make a sonic modeling thru winsrep.

Interestingly, it seems there are/were two variations of the Waldorf.

RLA from the Empire roller rink

53376

RLA from Club Zanzibar

53377

53378

If you wish to contribute to this project, then simply help with whatever insight you may have. BTW Drivers would be 2240h (fs30) for effortless oomph under 50Hz.

[djmike]

Looks like they were selling the prototypes and making improvements as they went. There is a guy on this forum that built the Studio 54 models. I asked him for the plans.


Here is the catalog info:



The Waldorf
tri-amplified speaker system featuring a front radiating, rear horn-loaded bass unit with two 15" bass drivers and two 15" mass-loaded passive radiators. The mid-range consists of a JBL horn lens coupled to a 2" compression driver while a gauss tweeter handles the high-end.
The Waldorf is also designed for use with the RLA X-6000 electronic crossover so that linear phasing can be obtained through the use of the special time-delay circuit. The Waldorf is also available in a bi-amp version and can be purchased with various compression driver/bass driver combinations. Designed for vertical or horizontal applications.
DIMENSIONS: 61.5"H x 36"W x 30"D (74" high with horn).
WEIGHT: 385 lbs.

Funny thing about sound installers is that, many times no one has trained ears like they do. They have to make changes to fit a particular venue. I read an article about Zanzibar some time ago that it has some particular challenge due to the size (seems like a low ceiling in one part) and that Richard had to make do. Sounds like they had a few options for the 15". I can't tell from the size of the GSA cabinets if they are 15 or 18, have you asked him?

Mike


I am still holding on it. The drafts are done for twin 18" drivers. Progresion curve is nice but I am a bit puzzled by how short the horn is as it is tuned to 40Hz with a mouth that is able to handle much lower. I still have to make a sonic modeling thru winsrep.

Interestingly, it seems there are/were two variations of the Waldorf.

RLA from the Empire roller rink

53376

RLA from Club Zanzibar

53377

53378

If you wish to contribute to this project, then simply help with whatever insight you may have. BTW Drivers would be 2240h (fs30) for effortless oomph under 50Hz.

[Ruediger]

... featuring a front radiating, rear horn-loaded bass unit with two 15" bass drivers and two 15" mass-loaded passive radiators ...

two 15" mass-loaded passive radiators ?

I do not see where the two passive 15 " drivers could go in this cabinet, and I can not imagine a construction with these components.

And a response flat down to 50 Hz can be achieved with much less effort.

I have heard an RLA system myself, in the Dorian Gray at FFM airport, but something does not fit.

About the time when RLA was in business, a quack here in Germany built similar systems: Hans Deutsch with his infamous "Horn-Resonator".

Ruediger

[Lee in Montreal]

I don't see either what passive rads can do in a compression chamber that needs to be stiff to... compress.

Interestingly, I always wondered why nobody has ever tried placing the woofers not on the top front panel, but on the 45° mid panel as it would greatly help enlarge the horn length by a good 2" feet. As long as the cabinet is used below 80Hz, radiaton of medium frequencies wouldn't be a problem.

[djmike]

You guys have photos of some of the more famous Waldorfs and they are both different. RLA only built five of the 6000 crossovers from the catalog. I doubt that very many Waldorfs were ever built. I think they were designed for the TAD or Gauss 15" woofers and made to go low by being tall and sensitive by being hyperbolic.

Mike


I don't see either what passive rads can do in a compression chamber that needs to be stiff to... compress.

Interestingly, I always wondered why nobody has ever tried placing the woofers not on the top front panel, but on the 45° mid panel as it would greatly help enlarge the horn length by a good 2" feet. As long as the cabinet is used below 80Hz, radiaton of medium frequencies wouldn't be a problem.

[djmike]

Three hundred and 85 pounds!


You guys have photos of some of the more famous Waldorfs and they are both different. RLA only built five of the 6000 crossovers from the catalog. I doubt that very many Waldorfs were ever built. I think they were designed for the TAD or Gauss 15" woofers and made to go low by being tall and sensitive by being hyperbolic.

Mike

[Lee in Montreal]

Here's where I am now. I will probably alter the first 90° bend on the upper right to make it smoother and remove any possibility of reflection. As you can see, the cabinet has 60" internal height and it is difficult to make the horn longer while keeping the simplicity of the path. On the original volume, only the 192L chamber is used, but it can be enlarged to 270L by using both volumes and probably allowing to go deeper.

53435

[louped garouv]

two 15" mass-loaded passive radiators ?

I do not see where the two passive 15 " drivers could go in this cabinet, and I can not imagine a construction with these components.

And a response flat down to 50 Hz can be achieved with much less effort.

I have heard an RLA system myself, in the Dorian Gray at FFM airport, but something does not fit.

About the time when RLA was in business, a quack here in Germany built similar systems: Hans Deutsch with his infamous "Horn-Resonator".

Ruediger

I don't think that the passive radiator version was ever actually offered commercially...
It was in development, but not ever refined enough to be offered to clients...

I believe that I read that on the wave music tech talk forum a few years back...
probably from Scotty, Shorty, or Ed in their more historical framework posting sessions....

Gary Stewart likely may have some knowledge of this prototype design also....
:)

[djmike]

Looks great!


Here's where I am now. I will probably alter the first 90° bend on the upper right to make it smoother and remove any possibility of reflection. As you can see, the cabinet has 60" internal height and it is difficult to make the horn longer while keeping the simplicity of the path. On the original volume, only the 192L chamber is used, but it can be enlarged to 270L by using both volumes and probably allowing to go deeper.

53435

[Lee in Montreal]

Build of a single driver Waldorf starts are picture #69

http://www.myspace.com/soundmanshorty/photos/43255154