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 !!!

[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

[Mr. Widget]

That, sir, is a damned respectable frequency response.

Yeah... all the way out to 8KHz.

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?

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

[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.

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..........

[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

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 . . .