Richard Long's Waldorf restoration

[Lee in Montreal]

That is true. And another much larger one in the lower back, right?

Ruediger

The Jensen Imperial sounds great without a Boombox and Richie didn't have digital crossover. Therefore I can ^robably do much better in 2012 than Rich did in 1979. Also I don't have a boombox on my but used eq from the DCX2496 and the 4520s sound real good.

[louped garouv]

The Jensen Imperial sounds great without a Boombox and Richie didn't have digital crossover. Therefore I can ^robably do much better in 2012 than Rich did in 1979. Also I don't have a boombox on my but used eq from the DCX2496 and the 4520s sound real good.

I had thought his nickname back then was 'dick short' or something.....
but i wasn't there, don't really know nuthin... only have heard a few old timers talking...

anyhow.....

Please Don't discount the old gear Lee...

I have a few of the RLA and Acoustilog pieces mentioned in that AES paper that Long/Fierstein submitted back when... although not nearly as flexible as a DCX2496, they do still sound very nice when carefully deployed...

you don't need the flexibility of digital when you are having custom electronics manufactured for your installations -- is how I see it...

[Lee in Montreal]

Please Don't discount the old gear Lee...

1972 Technics SL1100a
1977 Technics RS-M85 Twin motors Direct Drive tape deck
2 late 1970s Yamaha P2200
2 early 1980s Yamaha PC2002 and PC1002

Plus the usual early 1980s JBL drivers.

Don't worry, I don't discount the old gear. Quite the contrary ;-)

[Eaulive]

only if you are playing the older disco, soul, and funk cuts...

those boomboxes can add too much synthesized
bass to more modern productions/works -- of course -- IMHO and YMMV

True. I have the DSP version of the 120A in my driverack and it sounds horrible on newer recordings with already lots of VLF material.

[Lee in Montreal]

That is true. And another much larger one in the lower back, right?

The tall gap at the back is a cost cutting measure. Instead of using a 60" tall rear panel, it is only 48" tall. Therefore a 48" x 96" sheet can do two rear panels.

Carl contacted me to know if he could start posting his progresses. Expect some pictures soon. Notice that I made the first bend differently from a Waldorf. It is rounder and therefore avoids any return/reflection. More difficult to build but bass shall be cleaner.

only if you are playing the older disco, soul, and funk cuts...

those boomboxes can add too much synthesized
bass to more modern productions/works -- of course -- IMHO and YMMV

May I add that such a boombox may be needed with bad vinyl pressings only. I have hundreds of 12" singles that sound much better than any CD. They are extremely dynamic and they go loooooooooooowww. No need for enhancement there.

[Ruediger]

The tall gap at the back is a cost cutting measure. Instead of using a 60" tall rear panel, it is only 48" tall.

I did not mean the tall gap at the back. I meant the SCOOP itself, it is the 2nd 90-degree bend.

I also did not mean to suggest that You integrate a boom box. I meant that what You remember as the sound of the Waldorf may be the sound of the dbx and the Bertha combined.

Ruediger

[Lee in Montreal]

I did not mean the tall gap at the back. I meant the SCOOP itself, it is the 2nd 90-degree bend.

There are many ways to end up with the exact same progression on that end, while the scoop has different configuration. Usually you gain or loose 5 or 6 inches of horn path. I designed mine so that it is not really a 90° bend anymore, and it is meant to avoid any possible cancellation. No wonder the scoop is often called a "slide"

[louped garouv]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

[Lee in Montreal]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

Back chamber determines upper cut-off. Very important if one wants to use the speakers in the midrange. In my case, I didn't even bother as I'd use them for bass. But the panel separating the back chamber and the "lost" volume will be removeable. Therefore some testing will let us know about that. Throat height is a copycat of the original Waldorf.

[Ruediger]

Lee,
Is there a math equation for determining/optimizing the back chamber's volume for a particular driver?

The phase at the rear of the speaker is shifted by pi which corresponds to 1/2 wavelength.

At the frequency where the horns length is 1/2 wavelength the total shift is 2 pi or 1/1 wavelength, which is zero under steady state conditions.

Down to the frequency where the horns length is 1/4 wavelength and up to the frequency where the horns length is 3/4 wavelength the sound from the speakers front and from the horns mouth will add to each other, below and above they will subtract from each other.

For a scoop the frequencies might be 40 Hz, 80 Hz and 120 Hz. The rear chamber should function as a low pass below 120 Hz and should block frequencies above 120 Hz.

There is a paper from D.B.Keele about how to design a horn from the drivers TS parameters. The calculations are for a front loaded horn. The front chamber of the front loaded horn is the rear chamber of the rear loaded horn, and the rear chamber of the front loaded horn has no counterpart in the rear loaded horn (is infinite).

The Keele paper is in the technical references thread of the general audio discussions forum.

Ruediger

[Carl_Huff]

The paper that Ruediger describes can be founds here on DB Keele Jr's personal website.

It's the 11th paper and 2/3rds down the page. "Low Frequency Horn Design using Thiele/Small Parameters" http://www.xlrtechs.com/dbkeele.com/papers.htm
____________
Best Regards,
Carl Huff

[Charles0322]

I have heard these style Waldorfs from RLA and believe this cabinet was meant to be used in a double configuration, utilizing 4 15" drivers.. with the real low end provided by the enormous "Bertha" cabinet

Great to see another fellow Montrealer dedicated to JBL and its mutations.. I fell in love with JBL for it's use in disco systems in local Quebec nightclubs.

All the best, Charles

I'd be actually very interested to hear from people who have factual experience with such Waldorf because numbers themself don't make sense to me. Let me explain. From redrawing a Waldorf, and with the confirmation from Shorty's restoration pictures, I can say with assurance than the horn path is not longer than a 4520. 8ft for the 4520 vs around 6.5ft, which is in fact even shorter than a 4530. So, theorically, the Waldorf is not designed to go low. The main differences that I see are as follow: bigger mouth than the 4520 and a bigger rear chamber which should translate into a rounder type of bass at, I suspect, a certain loss of efficiency.

The advantage of the Waldorf horn design compared to a 4520-4530 is that the Waldorf doesn't have two consecutive U shaped corners. In fact the Waldorf has only one 90° bend at the upper back (like the Jensen Imperial from which it was inspred), and that bend can even be easily rounded up to avoid resonance and cancellation.

I still think that a back loaded horn with a 2.9m path (9.5ft) tuned to 30Hz and using a pair of 2240 woofers with Fs30 remains a better alternative. But first I must hear from people who have compared the Waldorf with a 4520.

[Lee in Montreal]

In some ways, I prefered the sound from my 4530 over the 4520.

4530 have a tight articulate bass and impressive kick. It's missing some roundness in the bass though. The Waldorf has the same 7ft horn length as the 4530 but with larger mouth and much bigger rear chamber. which should allow to get tight yet deper bass. I think it will be an improvement over the 4520 and 4530.

[Charles0322]

In some ways, I prefered the sound from my 4530 over the 4520.

4530 have a tight articulate bass and impressive kick. It's missing some roundness in the bass though. The Waldorf has the same 7ft horn length as the 4530 but with larger mouth and much bigger rear chamber. which should allow to get tight yet deper bass. I think it will be an improvement over the 4520 and 4530.

I was an employee of Stereo since day 1, after the first fire.. I no longer worked there.. I have been recently and am not impressed with the changes.

I am looking into options for a smaller style system.. some flying stacks mixed with RLA emeralds..

was looking into driver options, JBL, TAD, BMS perhaps the homegrown Transparence..

2395 and walnut 2397 combo maybe.. within a 4350 style flying cabinet.

Some of the DIY work on here is on par with exceptionally fine cabinetry. I myself am a cabinet maker and although speakers often get dismissed as "boxes" the pride and craftmanship on this board is inspiring to say the least.

On the Waveboard I have been pouring over the thread where they are talking about mixing various types of cabinets

LansingHeritage is one of the most interesting and informative sites for my interests.

[Lee in Montreal]

On the Waveboard I have been pouring over the thread where they are talking about mixing various types of cabinets

LansingHeritage is one of the most interesting and informative sites for my interests.

Yeah. I tried to pitch in on that thread. But it seemed that some had the universal truth... Not fun.

Glad to discuss with somebody from Stereo. One of the "hot spot" around the world for scoop fans and RLA derived speaker systems. Been there about 10 years ago. Still need to go back to take measurements ;-) I don't remember what model of Levan horn was used. The 30" deep of 48" deep. I wonder how many stacks they now run. 3 stacks, 6 stacks. Also, those Waldrof, are they with 18" drivers now? They look odd in some way.

I am organizing a big indoor party this summer in Quebec City for 100 people, celebrating "Shoeclack déchainé" which was a punk/new wave bar that lasted from January 1980 to end of 1984. I'll bring my system and will probably rent some more on location. if there wasn't a racecar in my garage, I would store some PA equipment. ;-)