Description

This is a system we designed pretty much from scratch. It started by finding a small retirement house with a room that could be converted to a listening room/home theater. This proved to be quite a challenge since home theaters were almost unheard of in 1986, the year this home was built.

Removing a door & window, and covering what remained with a wooden wall made this mostly-rectangular room a good place to start. The old coat closet behind the right speaker now houses the turntable [sandbox platform] and stores vinyl LPs. The door is padded with acoustical foam and covered with a black long-fiber cloth to aid in corner resonance absorption.

This room dimensions and accompanying large TV screen literally dictated the maximum size [and their position to a great degree] of the speakers. Although the brand names and models of the gear in our system appear, know that none [yes, none] are not of original design. All have been updated, improved, and/or redesigned in some regard. I'm an EE and the first thing I do after buying something is to take it apart to see what cost-reduction methods were used to increase profit margins. The next step is to undo these compromises and give the gear the opportunity to be what the original design engineer hoped it to be.

Speakers are dipoles modeled after the old Infinity RS-1B using a single amplifier in an all-passive design. The woofers are not active but rather passive bass-reflex design with rear mass-loaded slot ports.

The subwoofer does have its own amplifier [behind the L channel speakers] but the rest of the system is designed to run off of one stereo amplifier.

The equipment rack is designed to accommodate the equipment in the space remaining between the speakers. It is constructed from 1.5" laminated bamboo sheets using 3"x3" legs also constructed from this same bamboo. 1/2" threaded rods run through the center of the legs fastening everything together.

There is a large diffuser behind the equipment rack, a gift from a friend for helping him upgrade the crossover network in his otherwise excellent Vapor Audio speakers. What cannot be seen is the acoustic treatment behind the wall-mounted TV, the hiding place of a very nasty room resonance.

Wall-mounted tapestries conceal the other room absorbers flanking the speakers. A sculptured rug on the right wall works very well as does the tapestry on the left wall just above the subwoofer. Artwork also contains absorbers and are gapped 1/2" from the wall.

The woofer boxes are still a work in progress. The large concrete pedestals provide the appropriate height for these boxes while waiting for the final cabinet design to appear.

The television is a Sony XBR-85X900H, an 85" 4k set that provides some pretty nice resolution for 4K movies and Over-the-Air content. Our HDHomeRun 4k OTA recorder connects to our Sylology 1515+, a 24Tb server. This server is also used for streaming of audio files and stores our ripped [MKV] 1k and 4k movies.

Explanations of modifications to each of the components are included in their individual descriptions.

Oh, BTW, this system is entirely powered by the sun.
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Components Toggle details

    • McIntosh MC2100
    I'm the original owner and have had this amplifier since 1972. Being an EE, I've rebuilt it four times, the last version upgraded all solid-state devices to current McIntosh versions. All internal wiring was changed to OCC with a total of 200,000uF Kendeil capacitors in the main power supply. All FWB were changed to Schottky diodes and all ground loops removed. Original EI power transformer was replaced due to a lightning strike with a high-current toroidal version.

    This is a very quiet and responsive amplifier rivaling some of the best designs of today. It is very tube-like in its sound, probably due to their high-quality output transformers [autoformers]. At 135W RMS per channel, both channels driven, it is a nice match to the 95dB/W/m sensitivity speakers connected to them.

    It still has the original unbalanced input stage and it is there that things could be improved. But as it is with a signal-to-noise ratio of 105dB, it is good enough until I can find something that is its superior.
    • OPPO UDP-205
    The OPPO is at the heart of our HDMI switching and also our only DAC. This model is fairly good from the factory but with a little help it can be transformed into something very respectable.

    Again changing out all of the electrolytics to Nichicon UKW series capacitors of twice the original value, and changing out the main analog power supply to Kendeil 20,000uF, the tonal accuracy, resolution, and dynamics were greatly improved. There were a lot of ground loops built into this model that were pretty easy to eliminate also.

    The digital power supply was replaced with a linear toroidal version and that brought everything into line. Audio and video greatly improved once the regulators were changed to the Belleson discrete versions and the bridges replaced with discrete Schottky diodes.

    One day I will address the clock jitter but that remains to be something off in the distant future.
    • Audio Research LS-27
    Being fond of tubes but having to use a small listening room, I decided on a tube hybrid to avoid heat build-up. The LS-27 is a nice piece of gear to fill that requirement.

    Being 10 years old when I bought it, it was time to swap out the aging electrolytic capacitors, again to the Kendeils increasing the power supply capacity from 2,820uf to 4,080uF. All others were replaced with Nichicon UKW series. I've also replaced key resistor styles to non-inductive versions and replaced the low-voltage regulators with Belleson discrete ultra-low-noise versions.
    • APC S20BLK
    Line conditioning is provided from a much improved APC S20BLK.

    I replaced all of the rear panel outlets with hospital-grade versions correcting all of the built-in ground loops and replacing all internal wiring to OCC at the same time. I had to make a new rear panel to fit these outlets since the room to accommodate them internally was physically not possible.

    Several stages of additional RF and EMI filtering was added to improve noise rejection.
    • Custom Design Planar speakers
    The speakers are of my own design modeled after the Infinity Reference Standard 1B. The old IRS models had an appeal to me from their birth and my versions indeed do them justice.

    The 12 midrange drivers were originally from Monsoon PC speakers. I had to completely rebuild each one of them since the magnets had all but disintegrated. With a lot of patience and some magnets from Bruce Thigpen [he licensed the driver design to Monsoon], they were completely restored and their sensitivity improved.

    The tweeter is a Mundorf AMT and the super tweeters are Monacor RBT-95. Panel layout took fourteen iterations in various lengths and widths before finalizing the design. A friend built the final panels after I was happy with the driver layout.

    The woofers started out as a cardioid design with some tips from a local manufacturer but the baffle step issues just could not be resolved passively. Weird phase issues ensued so the design evolved into a slot-loaded rear port. I still have to rebuild the prototype cabinets but they sound pretty good as they are waiting for me to finish other aspect of the system with a higher priority.

    The crossover networks are all phase-coherent Bessel fourth order using OCC wiring and of course quality components with the super tweeter network using all Teflon capacitors. Each network pass band is confined to its own external PC board so with a 4-way system, each speaker has four outboard crossover boards.

    Both speakers use hand-made star-quad wiring, one speaker wire to each crossover network board, and one speaker wire from the crossover network board to the speaker panel. Each network board uses non-magnetic stainless-steel 1/4" bolts, nuts, and washers with solid copper terminals and more OCC wiring.

    All panel wiring in this speaker is hand-made OCC star-quad and attenuators are all of 0.01% or better T-pad designs. This permits maximum power transfer and matching from the output impedance of the amplifier to the input impedance of each driver. If one measures the impedance plots for each driver through these T-pads, the impedance does not vary and is precisely what the crossover network expects to see. As one could expect, this takes a while to achieve since off-the-shelf resistor values may not be what is needed and series-parallel arrangements are required.

    As a side note, I have found that the best sounding resistors used in the attenuator circuits are of the Nichicon chassis-mount non-inductive variety. I've also used heat sinks on these resistors to maintain better resistance stability.
    • Schneider Electric Photovoltaic Power System Conext SW4048
    This is where the power comes from for our audio/video system. All AC mains power comes from these two 48V battery banks [[email protected]] and converted to a pure sine split-phase 120VAC inverter. One phase is dedicated to the audio/video system and the other phase runs the rest of the house with the exception of the air conditioner and water heater.

    The batteries are normally recharged from 2,400W of roof-mounted photovoltaic panels. This system will run our entire house for two days without the need for recharging the batteries. During prolonged periods without the sun, the inverter can also be switched to recharge these batteries.

    A dedicated distribution panel from this system provides short 8AWG runs to the home theater.

Comments 2

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Owner
It is literally a labor of love. Glad that you see this love and understand the importance in some of the things I've done. I encourage anyone to do the same.

inline_phil

128x128
Cool system and nice job modding it to wring the best performance out of everything!

jond

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