This system doesn't actually belong to me . . . but I designed and built it in its current form for the owner, so I figured it would be appropriate for me to post it here.
I feel that the origins of true 'high-end' audio are in systems like this one - built in the mid-20th-century as comissions from wealthy music lovers, who themselves don't really care too much about equipment. This system was originally purchased by a midwestern dentist who was an avid classical music enthusiast, and simply wanted the best possible sound in his home. So in about 1954, he put his faith in his local custom stereo dealer, and had a top-notch monaural system custom-installed in his modest 900 sq. ft. suburban house. Speakers were all JBL -- 4 15" D130 woofers, and a big slant-plate 537-512 horn with 375 driver. Preamp and Amp were Marantz (models 1 & 2), with a Scott turntable, Grey tonearm, and Fairchild cartridge. He was thrilled.
About two years later, "stereo" was the new thing that he had to have. So of course, he bought a duplicate set of the JBL speakers and Marantz preamp and amp - with an Ampex 121 tape recorder . . . and all of this was again custom installed into the walls of his home. In 1960 he added 2 JBL 075 super-tweeters, and this would be the driver complement for the next 47 years.
In 1961, the dentist was becoming increasingly confined to a wheelchair due to the affliction of Multiple Sclerosis, and was spending most of his time at home with his music collection and his hi-fi system. He decided to build a new house with two goals in mind -- first, to have everything accessable from a wheelchair . . . but also (probably more importantly), to build a dedicated listening room.
This installation is what is shown in my "before" pictures. The loudspeakers were installed in an infinate-baffle arrangement, using the two-car garage (!) as an enclosure. The demising wall (used as a speaker baffle) is 3/4" plywood screwed and glued to the studs, and then filled with a couple thousand pounds of sand. A very thin grillecloth placed over the front of the speakers is flush with the room's wood paneling and matches it perfectly - making the whole system completely invisible. The power amps were mounted in the unfinished basement below, and all of the source equipment was hidden in a cabinet at the opposite end of the room, at wheelchair height. At this time, the Scott turntable was replaced with a Thorens TD124/SME 3009 with an Ortofon cartridge.
The dentist enjoyed this system until his death - I'm guessing sometime in the early-to-mid 1980s. His widow didn't use it at all, so it sat dormant until she died in the early-1990s. Fortunately for the classic hi-fi, an attorney was looking for a new home, and looked at several . . . in his words: "I didn't like any of them. But this house had the stereo, and that's what mattered." The attorney had a passion for jazz very much like the dentist's passion for classical - and upon moving in, turned on the system. It crackled and popped, but came back to life and started to play music again. The attorney connected his existing CD player and cassette deck and used it.
It was around this time that I first became involved, as the main high-end audio servicer in town. The original pair of Marantz mono preamps had been replaced with a McIntosh C26, but everything else was unchanged from when it was installed. I rebuilt the Marantz power amps and the Thorens TD124, and installed a Shure V15-V. A shot of cleaner on the crossover L-Pads was all that was required for the speaker system.
The dentist's old system continued this way for many more years, running on average about 5-10 hours a day. Except for a few new sets of EL-34s and an occasional scratchy control, no service was required. I left the business of servicing high-end audio, but would still perform maintainance on this system, mainly just to make sure it was preserved. And then in early 2007, the attorney informed me that his house was simply getting way too small for his family (and his CD/record collection), and they would have to move. And he wanted to take the stereo with him . . . and since it had made one move already, I thought, why not? But in the tradition of the dentist, we'd have to improve it a bit in the process, without ruining its essential character.
Conceptually, it would still be a built-in system, integrated with custom cabinetry around it - fortunately, I had the talents of a master cabinetmaker at my disposal. But there was no chance that a garage or attic could be used for an infinate-baffle arrangement, so I had to design enclosures to get as good (or better) bass response from a much smaller volume, and still use the same drivers! The other issue was that the 537-512 slant-plate horn is huge, and requires considerable clearance behind it - which was simply not available at the new home.
My solution was to turn a three-way system into a four-way. All of the drivers were rebuilt with new cones/diaphragms, as they had deteriorated a bit in their 50-year-plus lifetime. So two of the 15" D130s (per side) were rebuilt with original-style cones, which were put in a sealed box to handle the mid-bass - these would preserve the midrange quality of the old system. The remaining two were rebuilt with 2235 cones (heavier with much lower Fs of 20Hz), mounted in a reflex cabinet to handle the low bass, and make an improvement over the old system. The rebuilt 375 midrange drivers were mounted to new 2382 constant-directivity horns (solving the depth/size issue), and the 075 tweeters were changed to 077s, which have a wider coverage angle that's a better match to the 2382.
I designed and built new fourth-order passive crossovers for the mid-bass, midrange, and tweeters - these are all run from the original Marantz amplifiers. A new McIntosh MC275 MkV was added for the bass, with an Ashly electronic crossover. The speaker cabinets were built as separately from the surrounding cabinetry, and have a 1/4" gap around all sides for vibration isolation. The turntable platform extends through the back of the cabinet and is anchored to the wall to isolate it from both the speakers and the cabinetry.
So what does it sound like? Not suprisingly, the sound is very much like a pair of big JBL studio monitors - they have the timbre and punch of a pair of 4350s, but the midrange and high end has the smoothness of something like the 4435s (big butt-cheeks). Big, effortless dynamics, and it plays WAY loud, but I enjoy their presentation of solo classical piano as well. The dentist would have been proud.
Finally, I'll put in a shameless plug for my cabinetmaker, who for the most part, made it all possible:
Mid-1950s vintage midrange compression driver. The 375 was the first with a 2-inch throat and a 4-inch voice coil, and was also used in JBL's flagship Hartsfield and Paragon systems. This is an early "hump-back" pair.
JBL 2382A
Modern constant-directivity horn, 120°x40°. 2
JBL D-130
Mid-1950s D130 baskets and Alnico V magnets, with modified magnet structure to use a new JBL E130 cone kit. Very lightweight curvilinear cone with an aluminum dustcap to extend the frequency range. These are 16-ohm versions, wired in parallel, mounted in a sealed box about 4 cu. ft. in volume, to handle the mid-bass.
JBL 2235
Mid-1950s D130 basket and Alnico V magnet, with modifications and installation of new JBL 2235 cone kit. Heavy, straight-sided cone with high-compliance suspension and mass ring, for low-bass use. Each pair is mounted in a reflex cabinet of 7.9 cu. ft, tuned to approx. 33 Hz. 8-ohms, wired in parallel.
JBL 077
Horn super-tweeter with Alnico V magnet structure. The 077 was also used in JBL's L300.
Marantz Model 2
Stunning, rare vintage amps. I also have a pair in my own system, and can't say enough about how good they sound . . . so I won't even try. These amps run the mid-bass (D-130), mid horns (375/2382A), and tweeters (077) through a passive crossover. This photo is from their previous installation in the 1961 house, taken in 2007.
McIntosh MC-275 reissue
Current model tube amp, runs the low-bass 2235s.
McIntosh C-26
Mid-1970s vintage solid-state preamp - fully single-ended class A discrete throughout. Tube guys turn their nose up at the C26, but I think they sound much better than the tube-type C20 and C22. An AC wall adaptor is plugged into the swiched outlet, which triggers a McIntosh PC-4 relay power controller located by the amplifiers in the basement. Turning on the preamp thus exerts power control on the amplifiers.
Thorens TD-124
Classic idler-drive turntable. Mounted at convienent cueing height.
SME 3009
This is a special version of the 3009, with a fixed mounting collar instead of the usual sliding type, and branded with both the Shure and SME names. These were allegedly distributed by Thorens, and sold to dealers as a package including a TD-124 armboard, as a bolt-in, pre-aligned setup.
Ortofon 2M Blue
A recent replacement for the Shure V15, which was damaged. Mounting geometry is identical to the Shure, which was essential as this tonearm has no overhang adjustment.
Denon CDR-W1500
Dual-transport CD player-burner.
Nakamichi BX-150
2-Head cassette deck
Ashly XR-1001
Fourth-order stereo two-way electronic crossover. Set at about 100Hz, Butterworth alignment -- lows go to McIntosh MC275 to drive low-bass, highs go to Marantz Model 2s to drive mid-bass/midrange/tweeter. After careful adjustment, the crossover is placed at the bottom of the equipment cabinet under a cover, to prevent accidental changes.
Custom Passive Crossover
Fourth-order, Butterworth alignment. There wasn't the budget for super-fancy parts, but still all Solen film caps, air-core inductors, and 1% resistors. Mid-bass to mid-horn crossover point is 820Hz, and the tweeter high-pass is at 9.5KHz. No low-pass filter is used on the mid horn, as it has a natural approximate fourth-order rolloff. A conjugate network was used to offset the voice-coil inductance of the woofers, and all filters were calculated to the actual measured driver impedances in the transition region.
Custom Level Controls
I was nervous about the homeowner possibly wanting the overall timbre a bit brighter or darker, so as part of the passive crossovers I included precision stepped level adjustments, allowing both the mid-horn and tweeter to be adjusted from -3dB to +4.5dB in 1.5dB increments, all set by a series of 1% precision resistors. Actual attenuation at 'Flat' 0dB setting is -12dB on the mids, and -6dB on the tweets. But in the end, I needn't have worried . . . it measured flat on the '0dB' setting, and we both liked this setting the best. Oh well.
Transparent CL2TW
Transparent's standard 12ga custom-installation speaker cable, used throughout.
1961 Installation back view of
This is the view from the garage of the 1961 home, used as an infinate-baffle enclosure for the loudspeaker system. The left channel is shown - photo is circa 2007.
1961 Installation midrange horn
This the front of one of the 537-512 midrange horn that was built into the wall of the 1961 home. It's big - the slant-plates are 36
Measured response of mid-bass and midrange
Quasi-anechoic response of just the mid-bass drivers and midrange horn. Crossover point is at 820Hz.
Under construction, low-bass cabinet
Low-bass cabinet by itself, during construction . . . this is the left channel, viewing from what will become the top. The notch in the side is to clear the compression driver for the mid-horn.
Thank you Kirkus. This is probably one of the best posts on this site and a fond reminder of what audio / hi-fi used to be like. You've managed to capture a bit of history here and make it timeless.
I loved the refurbed Marantz 2s in your other post. Must sound good too as Warren looks quite content on his perch.
I started out with the 275's original Russian-sourced, McIntosh-branded KT-88s .... But one developed a short immediately out of the silly 90-day warranty. So I replaced them with some unused American-made (Richardson?) GrooveTubes-branded 6550s that I had lying around from the mid-1990s, and it's been perfect since. Keep in mind that since the 275 only handles the bass, it's hard for me to asses the sonic character of the tube-swap.
You should be proud. That phase plot looks pretty smooth. I expect the crossover at 800 Hz was probably the trickiest piece.
When you have so much raw SPL power output available and no concern about trying to squeeze efficiency from low cost drivers (as in consumer designs which compete with eachother) then you can make all the right choices. Like using the port for what is should be used for - to damp and control the driver at extreme LF - this must sound great on a kick drum. Your design is opposite from the consumer box speaker approach. You started with uncompromising raw materials (high quality drivers with plenty of clean power) and then adjusted them to work together. In a consumer speaker the design approach is all about balancing compromises to get good sound out of low cost drivers and hit a good value price point with more money available for the important veneer and aesthetics. In your case, there is no expensive veneer. Thanks for the update.
Shadorne, I am of course happy to spout off about how I designed the speakers . . . glad you're interested.
The first thing I did was work with the cabinetmaker to figure out exactly how much frontal area and cabinet volume would be required, in general terms. I then did approximate volume calculations for the cabinets, and we went back and forth a few times to get the dimensions right, and to end up with both the mid horn and the tweeter at ear level, and on the same horizontal plane.
In my experience, JBL-Pro's published Theile-Small parameters have been very accurate, and the 2235 cone kits used for the low-bass drivers come pre-assembled with spider, voice-coil, and surround, so I could be pretty confident about most of them. The exception was Bl, because of the modified Alnico magnet structure . . . so I simulated the cabinet, while varying driver Bl . . . and came up with a slightly over-damped port tuning that made this parameter less critical.
The speaker box is actually two separate cabinets, both trapazoidial, and locked together to make a rectangle. So once I had the volume for the low-bass, the mid-bass simply got the rest . . . and it ended up being way more than enough to prevent a response peak. The mid-horn, its driver, and the crossover network actually sit in their own space on top of the mid-bass cabinet, and the tweeter is actually inside the low-bass cabinet. I have a picture of the low-bass cabinet on its own, under construction, that I'll put up.
After the installation, I played the 2235s full-range with a number of familiar recordings, and varied the amount of stuffing inside the box until I was happy with the bass room/speaker interaction on its own. The mid-bass drivers actually then had more low end than I had expected . . . and the Ashly crossover I used has a very handy transition-band tuning control. The result was that on the final crossover adjustment I could choose between a couple different types of mid-bass (D130s and 2235s) and had LOTS of control over the level and transition between them - and this was more than enough to get good results without any EQ. Bass traps, from an aesthetic standpoint, were completely out of the question.
Where I actually spent most of my design time was getting the transition between the mid-bass D130s and the mid-horn. I started by measuring the magnitude and phase response of D130s in their finished cabinet, then the horn in a baffle board; I did this in an elevated position and windowed the FFT for a quasi-anechoic measurement. I then measured the individual driver impedances across the whole audio band, and through experimentation came up with a conjugate network that flattened out the D130's impedance curve. The compression drivers, for all intents and purposes, had flat impedance curves.
I then designed an equivalent model of both the D130s and the mid-horn in SPICE, such that the magnitude (and thus phase) and impedances were approximately similar to my averaged response from the respective drivers, averaged across about 60 degrees on the horizontal plane. From there, I played with a couple of different crossover slopes and alignments until I was happy with the results in SPICE, then built the filters for these drivers, and re-measured the two together, in the finished cabinet. I'll put the resultant quasi-anechoic curve in a picture above.
Since I don't feel that my phase-domain measurements are accurate at higher frequencies, I simply designed a high-pass filter for the tweeter that was the complement of the mid-horn's natural roll-off, then adjusted for the sensitivity difference, and left it at that. And I figured if I was off a bit, I could compensate with the adjustable stepped tweeter level control. In practice, the mid-horn extends high enough in frequency where the tweeter is just the "icing on the cake" . . . it's not like a typical direct-radiating application where this transition is super-critical.
Anyway, there it is. Just a combination of careful measurement and design, lots of educated guesswork, and a bit of good luck.
BTW - I am sure you are aware of this - but when you place woofers into a wall (in your case a half wall) then you tend to eliminate rear wall quarter wavelength cancellation in the bass. This happens with all free standing speakers and results in comb filtering such that certain notes disappear (or are very weak) for the listener. My limited experience is that the bass and lower midrange is unequalled in this type of in wall speaker mounting, however, a downside is that you do get stronger room modes. FWIW - I found that bass trap treating the rear wall behind the listener became more necessary in this "soffit" mounted configuration. How did you deal with these issues ? Perhaps you did not experience a "before and after" sound test where teh room modes become more apparent. I am able to contrast the in wall sound to free standing by simply removing the speakers from their in wall mounting and placing them in the room.
I was quite lucky to have some pretty amazing documentation on this system's past . . . I found a quarterly newsletter from the original dealer, dated "spring 1968", that had a multi-page article featuring this system. Rumor also has it that this same system, but from the VERY first house, was featured in a 1950s Hi-Fi magazine called "Audiocraft", but I have yet to locate this one.
One thing that struck me many times during this project was how close the relationship must have been between the dentist and his audio dealer . . . and how we tend to reserve the highest suspicion for those people whose craft it is to separate us from our money: the "salesman".
But it really is a beautiful thing to take somebody who could just as easily spend their disposable income on a diamond Rolex, a boat, or a weekend in Vegas . . . and sell them a wonderful music system insted, that is used every day, and is loved and cherished for decades.
I agree with Garryh and Ekobesky. This is a prime example of good music and good design coexisting without sacrificing either for the sake of audiophilia.
Extremely impressive. Subtle and aesthetic yet no doubt has the dynamic capabilities, imaging and ultra low distortion of a full blown dedicated pro studio (pretty much all prestigious high end studio main monitors are installed the way you designed this system and these studio systems are used to impress the best artists and producers).
I find it surprising that in a hobby where nearly everyone makes a pretense to chase the best possible sound that we find so few purpose built systems like this.
Kirkus...what a great story! I don't think I would ever leave home...I have run into a couple similar houses that had wonderful sound systems built in. I think that is a great way to express a persons love of music. Makes me want to go out and build a custom house....
I agree with Garryh, and more than that, I think this is the kind of system we need to see more of. Audiophiles focus too much on cabling and tweaks and pinpoint imaging and perfect soundstaging at the sweet spot. But there are plenty of music lovers who could care less. A system like this reproduces music beautifully and yet makes sense for someone who doesn't want to arrange their living area around their audio system, and who wants to move around the house and enjoy music at the same time. This system disappears in the room and works in the real world. All that, plus lasting quality. What's not to love?
Bravo, Bravo! Really fascinating to see how this one system lasted and evolved. From a design point of view - simply stunning. This has to be the ultimate sleeper system - I not seen anything like it on the 'Gon.
