New digs for a classic system

[Beowulf]

Hello all,

This project is just so much fun, that I have to share it. Add to that the fact that this website has been so much of a help . . . here goes.

I have a client who owns a complete, intact hi-fi system from the late 1950s . . . it's a rare combination in a system of top components, decent system design, and wonderful workmanship. The original owner of this house bought most of the components in the mid-to-late 1950s (first mono, then a duplicate for stereo), and when he built this house in 1962, designed it specifically for the stereo system. He was a dentist who was afflicted with MS in his later years, and spent the last two decades of his life in a wheelchair, collecting classical music, and listening to this stereo system.

The current owner is just as much of a jazz freak as the dentist was a classical enthusiast . . . and we are very fortunate that he instantly recognized the value of the system when he bought the house. In his words: "we looked at three houses, and I didn't really like any of them . . . but this one had the stereo. So we bought it." But alas, the house is now simply too small, and the entire system is in the process of being moved.

Here's the original JBL speaker system:
8 D130s (4 per side), loaded infinate baffle to the garage behind
2 375s, affixed to 537-512 horns/lenses
2 075s, with L300-midrange-style slant-plate lenses (HL91?) stuck in front of them
2 N500s
2 N7000s

The whole system is absolutely invisible from the inside of the house, covered with a grillecloth that matches the paneling PERFECTLY. The wall they're installed is filled completely with sand . . . probably a couple thousand pounds!

[Beowulf]

I'll dig up some interior pix soon and post them.

But here's how it sounded right before it was dismantled . . . the 075s were intermittent (just look at the L-Pads!) and the traces were taken without them.

So the improvement list reads:
1. Rebuild all old flakey stuff for best performance/stability/reliability.
2. Fix the super-tweeter end of the spectrum.
3. Add some real bass.
4. Deal with that 250-cycle honk.

There is a plan for this . . . I'll post the cabinet renderings and system changes shortly.

[Chas]

Wow, very interesting. Please keep us posted on your progress. I have never seen a lens mounted in front of an 075. :)

[Maron Horonzakz]

That was the exact same speaker system I heard at DAVID BEATTY AUDIO..in Kansas City.. Awsome !!!:D

[Beowulf]

Hi Maron . . . it was Beatty who sold and installed this system. He and the original owner (Dr. Blender) were close friends.

Okay, here are some pictures of the inside. The flash makes the grilles WAY more apparent than they are in real life. Also, the homeowners don't normally have quite this much stuff in front of them . . . they were in the middle of packing for their move.

[Beowulf]

I found a bit more original-era documentation for the system - attached is the dealer's newsletter that highlights the system, from 1968.

[bigyank]

Very nice documentation and heart warming story. :D

Yank

[tensleep]

I certainly appreciated this story. It also makes me look at my home a little differently. I wonder how sheetrock filled with blown insulation works as a baffle? I've got the garage on the other side of the wall:hmm:..........

[Beowulf]

So here are photos of the electronics. The Marantz Model 2s are mounted in the basement, the rest in the cabinet at the opposite end of the room. The turntable is a Thorens TD124 with a SME 3009 and a Shure V15 type V. I rebuilt the Marantzes and the Thorens for him about ten years ago, and both are still running perfect . . . a new set of EL34s is all that's required. The preamp is a Mac C26, it probably replaced a pair of mono Marantz Model 1s in the mid 1970s . . . it probably needs a once-over. The commodity-grade tuner and CD deck will remain for now.

A couple of interesting things are the Dynaco stereo matrix-thingey built into the cabinet (the knobs to the right of the turntable) . . . this was long since disconnected. Also note the doorbell button here: this actuates a mechanism consisting of a very slow gear-driven motorized arm, some lever switches, and a Rube-Goldberg conglomeration of string and pulleys, all hidden behind and within the cabinet. The end result is that when you push the button, the turntable glides verrrry sllllowly out of the cabinet for cueing. Definately designed for somebody in a wheelchair.

[Beowulf]

And here are the plans for the new place. I worked extensively with John at Slice Speaker Repair in Kansas City to come up with the revisions . . . he's been an authorized JBL rebuilder for a couple of decades, and came up with some great ideas. For new custom cabinetry, I am very lucky to have a close working relationship with an incredible artist and craftsman here in town. Seems like a shameless plug, but his website is lots of fun to look at:

www.roundtreedesign.com (http://www.roundtreedesign.com)

First, just about all the JBL needed service, so it all came out and went to Slice. Since this system is for listening rather than for total eBay value, wax seals be damned . . . I want them to sound great, be well matched left to right, and stay that way for years. So the 075s and 375s were rebuilt with new diaphragms.

For the D130s, I was trying to come up with an enclosure to improve the bass response, at which point John had the idea to turn half of the D130s into 2235s, and run them as the low-bass in a bi-amped four-way system. I don't know exactly how he performed this feat, but it involved some work on a very expensive milling machine, and the results are very impressive. So I now have four "2235s", four D130s, two 375s, and two 075s that are fresh, perfect, and ready for another fifty years (maybe with a refoam for the 2235s along the way).

After much musing between myself, John, the homeowners, and Tim (of Round Tree Design), we came up with a workable cabinet layout, and those huge 537-512s simply wouldn't work in the new room, or they'd be so boxed-in that what's the point? We also don't have a garage behind it at the new location. Instead, the 375s will be mounted to new 2382s . . . which is perfectly suited to the new application. A pair of 077s will replace the 075s, as their pattern is a better match to the 2382.

The low-bass will be handled by a pair of 2235s on each side, in a box of about 8 cu. ft., vented at 31.5 Hz. The remaining pairs of D130s will be mounted in a 4.8 cu. ft. box to handle the mid-bass. Driver layout is shown below.

I wanted the D130s in a large box to make them sound as close as possible to the old infinate-baffle arrangement through the lower midrange . . . which I feel is part of the essential character of the old system. The D130s, 375s, and 077s will run all off of the existing Marantzes via passive networks . . . I'm planning on using a classic second-order Butterworth three-way arrangement, with the midrange wired anti-phase . . . but I'm going to measure the drivers in the installed cabinet before building the networks. For the bass, were adding a new McIntosh MC275 MkV tube amp, and an Ashly XR1001. I'll probably need a little EQ, so I have a Mac MQ107 parametric to add as well.

So right now we're waiting on cabinetry . . .

[Rusnzha]

Amazing system.:cheers:

[Beowulf]

It's exciting to see some progress -- we did quick mockups of all the cabinet panels and drivers today to ensure that everything fits. There are some pretty crazy angles on the low-bass cabinets . . . the top end has an extra little relief to clear the 375 on the mid-horn.

[JohnK]

That system is very similar to a built in one described in "Audiocraft" magazine in the late 50's, including the strange grouping of D130's and the Marantz 2's. The horn/lenses are the only thing different, the ones in the article were Hartsfield types. Actually, I think it's the same guy & the same system, I'll look it up.

In any case, your find is absolutely splendid. It's wonderful to see vintage systems in their original environ.

[Beowulf]

Hi John . . . I'd be really interested to see the article you describe, and I'm sure the homeowner would as well. By "the same guy", are you referring to the the dealer, David Beatty?

Beatty is actually the subject of some local folklore and speculation . . . the official story is that he committed suicide by jumping of a bridge (accounts vary as to exactly which one) into the Missouri river. But the body was never found, and it's still considered a cold case by the Kansas Buearu of Investigation. It's widely accepted that he was in financial trouble at the time of his disappearance . . . maybe he's just pulling a Richard Kimball act. But the parallel to James B. Lansing's death is an interesting one.

[JohnK]

The dentist. I think it's in the last issue of "Audiocraft". It was pictures from the first house I think, before he moved. I'm almost certain it must be the same system.

[Mr. Widget]

In any case, your find is absolutely splendid. It's wonderful to see vintage systems in their original environ.:bouncy:

I agree... I love that old stuff. Thanks for sharing it with us!


Widget

[boputnam]

...here's how it sounded right before it was dismantled . . . the 075s were intermittent (just look at the L-Pads!) and the traces were taken without them.

That, sir, is a damned respectable frequency response. I take it, without much, if any, EQ? Wow. There are guys here who would skin their teeth to get anything close to that.

Those 375's are just there, unsupported at the motor? Aren't they like 20-something pounds?

[John]

Those 375's are just there, unsupported at the motor? Aren't they like 20-something pounds?

Those horns are very solid and as long as the wall panel is as well, 20-30 LBS. is no big thing.

If they were mounted like that in cabinets, maybe???

But again if you have handled those horns they are very solid with thick walls:blah:

[Mr. Widget]

That, sir, is a damned respectable frequency response.Yeah... all the way out to 8KHz.:rotfl:

Actually it is outstanding especially when considering it's vintage. I guess the drop off above 8KHz is due to the 075s being intermittent or being way off axis. I wonder how well that lens worked with them?


Widget

[Beowulf]

. I guess the drop off above 8KHz is due to the 075s being intermittent or being way off axis.
Widget

Yeah, the L-Pads were crackly, and when the 075s were tested later, one side was kinda krispy, and the other side had very little output . . . as far as the trace is concerned, there was unlikely to be any sound at all coming from the 075s. And yes, this is without any EQ, about 25 degrees off axis from the 537-512.

The 375 as originally wired had no LPF, that is, it was driven directly from the HF side of the N500. Its output to me looks exactly like some of the published data I've seen for the 2440, clearly showing two slopes . . . but with the upper one shifted down almost an octave . . . I'm attributing this to probable metal fatigue and/or corrosion in the original diaphragm surround, lowering its resonant frequency. I originally thought that the 250Hz peak might have been an artifact of the transition from the D130s to the horns, but looking at the photos makes me realize that the width of the bookshelves corresponds pretty closely to a 250Hz-ish wavelength, and this is most likely to be a resonance from this cavity.

There are two things that really impressed me in this trace - first was how well the sensitivities of the D130s and the 375/537-512 matched each other - there's no attenuation on the horns. The other thing was how nicely the bass roll-off of the D130s seemed to be offset by their corner-loading in the room - below 125Hz-ish. Subjectively, it still sounds a bit bass-light, especially for a system with eight 15"s . . . but for mid-20th-century classical recordings (what it was built for), it's not really an issue, especially with judicious use of tone controls . . . which nobody frowned upon back then. What I was truly stunned by was how good this system sounded with speech . . . my jaw dropped when I heard an NPR newscast.

[Mr. Widget]

What I was truly stunned by was how good this system sounded with speech . . . my jaw dropped when I heard an NPR newscast.World's greatest radio speaker? :D

For years I had a pair of custom speakers out in my shop that were made up of Dynaudio, Focal, and B+W components... and a Dynaudio sub. When my audiophile friends would come over they would tease me about the overkill of the system since it played NPR about 90% of the time. Now I think I may have to upgrade to a new one now with 4 15s per side. ;)


Widget

[JohnK]

Found The Article. It was wriiten by David Beatty. It describes Dr Lester Blender & system. There are pictures of two systems, the earlier mono system & the stereo system. The house is the earlier house. It is the November 1958 issue. I sort of figured that there probably was only one system like that in the world, & you found it!


PM me & I'll send it to you.


JK

[Beowulf]

Finally, all of the cabinetry is completed, and most of it is installed, including the speaker cabinets. Couldn't be happier with the results . . . especially the perfect 1/4" gap all around the speaker cabinets themselves, which seems to have thoroughly decoupled them from the rest of the woodwork. The horizontal plane of the 2382s and the 077s ended up exactly at ear level when seated.

It's really interesting how HUGE the speaker cabinets are when they're sitting out in the open . . . something that 'normal' people would never have in their living room. But put a bunch of custom cabinetry around them, and they suddenly seem "very small", in the words of the homeowner.

[Beowulf]

So now I'm building crossovers. I originally thought that I would use 2nd-order filters, but after taking some measurements and playing around with a couple of different active crossovers I have lying around, I think that 4th-order slopes seem to work much better. The trace below is just the D130s and the 375/2382, crossed over at 818 Hz, 4th-order Butterworth alignment, wired out of phase with each other, with 12dB attenuation on the horn.

Also, since the mid horn has its own steep rolloff, I'm thinking that I'm going to run it without a LPF, and simply bring in the 077 at a (kind of) complementary slope.

[speakerdave]

That's a nice looking installation. What is the crossover frequency between the 2235's and D130's. Also, I'm surprised that 2 D130's are necessary. Could you go into the reason for that? I do like the idea of a large diaphragm working the midbass, but I would have thought one would be enough over a pair of 2235's.

David

[Beowulf]

Well, the main reason is that the old system had four 15" drivers per side, so the new system has . . . four 15" drivers per side. It did occur to me to halve the number of D130s, but once enough room was given to everything else, it wouldn't have really saved any space. And I had already sold the homeowners on so many other changes and a huge custom cabinetry bill . . . and it would have seemed weird to then justify why we weren't using all the speakers that we had.

In a purely technical sense, having two probably provides a bit of vertical pattern control in the upper bass, reducing the effect of early reflections off of the floor. :blah: And if you don't buy that, it at least increases sensitivity, and since the crossover between the D130s, 375, and 077 will be passive, that's definately a good thing, as the 375/2382 is still 12dB hotter than the D130s.

On the negative side, I noticed that when the D130s were crossed over to the horn at, say, over 1K, they produced some weird phase discontinuites (both audible and measurable) that I'm attributing to the interaction of the higher-frequency response from the two metal domes . . . this was one of the main reasons why I decided to go with fourth-order slopes, and keep the transition point just above where the 2382 starts to poop out. In retrospect, this could maybe have been avoided by putting an aluminum dome on the upper driver only, but I'm actually quite happy with the transition region as it is.

As far as the crossover point between the 2235s and the D130s is concerned, it will be in the range of 90-125, but since this is made with an active crossover, I won't have to decide until the final tweaking. The D130s actually seem to extend lower than I anticipated from the calculated box tuning, so the deciding factors will probably be much more due to room interaction than driver response.

[speakerdave]

Thanks for that. I've also found I like to lower the crossover point when using multiple woofers and have wondered if it is because of phase issues in the higher frequencies they cover, that is higher than the range in which effective acoustic coupling is occurring.

Perhaps the unexpected lower frequency response in the D130's results from acoustic coupling, which I think would increase response gradually in that setup from about 300 Hz down to about 150, and would be full from there downward.

David

[Beowulf]

By 'acoustic coupling', I take it that you're referring to the coupling taking place in the airspace immediately in front of the woofers? I suppose that that could be . . . but for some reason I associate this phenomonon more with higher SPLs - like in big line arrays. But those D130s are indeed very close to each other, and close to the floor . . .

I also have a bit of skepticism about the TS parameters I used for the calculations . . . since what I actually have are 16-ohm E130 cone kits in old Alnico D130 frames, and the published D130 TSPs are for 8-ohm versions. I tried to make some educated guesses about what would be different, which is why their box is bigger than a calculated Butterworth alignment for 8-ohm D130s. And there's the added bit that TS calculations only really work as intended if the driver behaves as a piston, and I thought the whole point of the "curvilinear" cone was that it doesn't. In contrast, the "2235" cabinet seems to measure very consistently to what the TS parameters predicted.

But whatever the cause, in this case the deviations from the predicted behavior is actually an improvement . . . :D

[jblwolf]

Great post!!:applaud:
I'm with Chad on the use of a lens on a 075,any comments on the affects of a lens on a 075?

[sssmokin99]

So was there any followup from BeoWulf on the final outcome of this project? It is fascinating from start to finish! As an aside, I believe that David Beatty (claimed to be) the "oldest" JBL dealer in the country. Or is my memory faulty?

I do remember their slogan: "Get the best and cry ONCE" :D

I wonder what Dr. Blender paid for it all in the beginning, too. It would certainly be priceless to him, with his career cut short by MS and being confined to a wheelchair.

[hjames]

Still, there's a lot of pictures of the final system on the cabinetmaker's site here -

http://www.roundtreedesign.com/portfolio/indoors/classic_stereo_cabinet.html (http://www.roundtreedesign.com/portfolio/indoors/classic_stereo_cabinet.html)

[sssmokin99]

Thanks, hjames! It is a beautiful installation and fantastic re-use of these components