Late in 1989, when my wife Lisa and I walked into Sound Goods, an audio video store in Mountain View, California, a nearly quarter-century-long love affair with the combination of Perreaux Electronics and Polk Audio SDA (“Stereo Dimensional Array”) speakers began. We had recently moved from Columbus, Indiana, to Palo Alto, California, and had decided that with a new home we needed a new stereo system.
While our aging AR turntable, Sony integrated receiver and Allison 6 speakers had served us well for almost a decade, the rise of digital music reproduction influenced us to make the transition to CDs from LPs and to upgrade our stereo system. This transition was motivated not so much by our conviction that the sound would be better with a digital system as by two other factors: First, our three-years-old daughter loved to play with the tone arm of our turntable – even as it was spinning -- and consequently had damaged most of our LPs. Second, I had begun working for NeXT Computer Inc., a company that was committed to facilitating growth of digital music recording and reproduction. The NeXT Cube, the company’s revolutionary computer system, in fact, was the first computer to be shipped with a magneto-optical drive as standard equipment.
Clockwise from top-left: Perreaux SA33 preamplifier, Polk Audio SDA SRS speakers, Perreaux PMF 5150 B power amplifier.
When we entered Sound Goods, nothing particularly notable occurred. Lisa went one direction and I another, as we “cased” the shop for a CD player, integrated amplifier, and speakers that appealed to us. Not until I encountered a very large (and, to my mind, beautiful) amplifier driving equally large and imposing speakers, had anything in the store drawn my serious attention. As I quickly learned, the preamplifier and amplifier were Perreaux’s then top-of-the-line SA33 preamp and PMF5150 amp, and the speakers were Polk Audio’s then top-of-the-line SDA SRS speakers. The source was a Sony ES CD player.
The Perreaux electronics and the Polk speakers were, to my mind, a perfect match with each other and with my desires. The sound was rich, deep, and palpably realistic, filled with nuances. The sound stage was broad and deep, and it appeared to be perfectly balanced. Regardless of the intricacies and dynamic range of the source music, the sound was reproduced with a sense of graceful ease, without any signs of strain or coloration. I had found the perfect system for me.
Then, of course, reality interrupted my reverie: Lisa, noticing that I had spent a considerable amount of time listening with undivided attention to this very large-scale system, inquired about what I was contemplating. After persuading her to listen to the demo system for a while, she acknowledged its extraordinary quality, but asked, “Where do you plan to put it?” She knew full well that our relatively small family room, where the system would necessarily be located, was not a reasonable space for this system, however remarkable its performance might be.
Clockwise from top-right: Sony CDP-C8ESD CD player, Perreaux TU1 tuner, Perreaux PMF 2350 power amplifier, Polk Audio SDA 1C speakers.
Later that afternoon we left Sound Goods with an excellent system for our needs and space: Perreaux’s TU1 FM tuner, SA33 preamp and PMF2350 amp; a pair of Polk Audio SDA 1C speakers, and a Sony ES C8ESD CD player. This system served us well for over 20 years, but I never forgot my infatuation with the Perreaux PMF5150 and Polk SDA SRSs – the sheer power and beauty of them, and the sound they produced with effortless command!
When our PMF2350 appeared to have developed a hum in late 2011, I set out to get it fixed and began exploring alternatives in case repairs were not feasible. My memories of the PMF5150-SDA SRS combination were as alive as they had been the day after we left Sound Goods some 22 years earlier; so, while the Perreaux distributor was diagnosing the PMF2350’s problem, I began casting about for a used PMF5150. Having moved into a more spacious home in New Hampshire, I simultaneously began looking for a set of Polk SDA SRSs.
Thus began a quest. While the PMF2350 was in the shop, I purchased a Perreaux PMF3150 on Audiogon (not quite the PMF5150 because none was available) and, shortly afterwards, a pair of Polk SDA SRS1.2s on eBay. As it turned out, there was nothing wrong with the PMF2350; even after 22 years it tested as operating completely within original specifications. Nevertheless, I had crossed a bridge to embark on an odyssey to find the best sound I could for my home system.
With the Polk SDA 1Cs the PMF3150 made a dramatic improvement. Most notably, at lower listening volumes, which Lisa prefers, there was little or no loss of detail or bass. However, because we began listening at lower volumes, the gradation of the volume control on our SA33 preamp became more critical, and this vintage preamp was not up to the challenge.
Clockwise from top-left: Perreaux SM6 preamplifier, Polk Audio SDA SRS 1.2 speakers, Perreaux PMF 3150 power amplifier.
I began researching Perreaux’s more recent preamplifiers. The SM6 preamp, introduced in 2006, jumped out as a potential, more contemporary replacement for our SA33. Coincidentally, one was available on Audiogon, and I quickly purchased it. Like the introduction of the PMF3150, installing the SM6 in our system made a remarkable difference. Not only did it provide far more satisfactory control of the volume, but it also made unmistakable improvements in the quality of sound reproduction in almost all respects. Even Lisa was becoming intrigued by my quest and its results!
Enter the Polk SDA SRS1.2s! Acquiring and arranging for transport of these 185-pounds-each speakers is a story in itself. Let me just say that, in my ignorance about the possibility of shifting driver magnets and other hazards, I blissfully engaged an antique shipper to package them, put them on a pallet, and ship them from Florida to New Hampshire. Perhaps, sheer dumb luck allowed them to arrive in uncompromised condition.
The huge, monolithic SDA SRS1.2s, brought another leap in performance to our system. The highs were clearer, more realistic, finer; the bass was incredible; the sound stage filled our room. Finally, after more than two decades, I had a very close approximation of the Perreaux-Polk Audio system I had coveted in Sound Goods. But, once the taste is whetted, the appetite is difficult to satisfy!
While we were clearly getting better and better sound, we were also exposing weaknesses in our system that had been masked by less capable components. As remarkable as the Perreaux SM6 and PMF3150 were in combination with the Polk SDA SRS1.2s, a “muddle in the middle” still appeared, for example, when I listened to one of my favorite recordings – Sir George Solti conducting the Chicago Symphony Orchestra playing Beethoven’s Ninth Symphony. It wasn’t that the sound was bad; rather, we just knew it could be better. But how to achieve the improvement we sought?
We tried two approaches: First, we acknowledged the limitations of our aged Sony ES C8ESD CD player. Second, as I had been exploring various audiophile sites on the Internet, I had become aware of the importance of interconnects and speaker cables, and suspected that our very basic cables could be improved upon.
Clockwise from top: Cambridge Audio Azur 840C CD player, Canare 4S11 Star Quad speaker cables, Audioquest King Cobra interconnect cables.
To address the first approach, after considerable research, we purchased a Cambridge Audio Azur 840C CD player to replace the old Sony. The 840C offered not only great performance as a CD player, but also provided a variety of inputs, including a Toslink port for use as a DAC with an iPod dock’s digital output. The latter was an important feature, not for serious listening, but to give us flexibility in having background music for dinner parties and other social gatherings. The 840C also fit our budget for this component.
To address the second approach, I had to overcome my prejudice that “copper wire is copper wire.” Again, after considerable research, I ordered Audioquest King Cobra interconnects and two different sets of speaker cables – a pair of Morrow Audio SP7 bi-wire cables and a set of Canare 4S11 Star Quad cables to use in a double-run bi-wire configuration.
The King Cobra interconnects were installed first, and we noticed an improvement. I say “we” very deliberately, because my wife is not subject to any “placebo” effect, and she is very discerning with respect to subtle variations in sound. This experience began to erode my “copper-wire-is-copper-wire” bias. Our experience with speaker cable alternatives further eroded my bias.
The Canare cables arrived first. I believed that I heard a significant improvement; Lisa heard a difference, but not one she considered an improvement. Rather, she judged the highs too bright and strident, and the overall sound harsh. As we let the Canares “burn in,” the sound improved, but not to my wife’s satisfaction.
When the Morrow cables arrived, they had already undergone a 200-hours-equivalent burn-in process by the manufacturer. Nevertheless, we wanted to give them more time to reach their full potential. At that point we invited a deeply experienced and knowledgeable audiophile friend of ours to join us for a “listen-off” between the Canare and Morrow cables.
He and I thought the Canares were more realistic, particularly in presenting vocal music – classical opera and operetta pieces. But Lisa still plumped for the Morrow cables’ warmth and depth – despite her initial predisposition in favor of the much less expensive Canare alternative. Lisa won. We have adopted the Morrow cables, which have gotten better and better over time. Lisa was correct.
The new interconnects and speaker cables, unfortunately, only emphasized the “muddle in the middle;” they did nothing to solve this problem. So, the quest continued to the next episode.
Lisa and I decided that our next step should be to audition contemporary speakers. Perhaps, the vintage SDA SRS1.2s just couldn’t resolve the complexity of midrange orchestral performances to our satisfaction. Without describing the intricacies of this stage of our quest, I will say only that in the course of auditioning various B&Ws, Thiels, Harbeths, Nolas, and Wilson Audios, among others, we were persuaded that before buying new speakers, we should look into contemporary preamplifiers and amplifiers. Could the Perreaux SM6 be improved upon? Was the Perreaux PMF3150 outdated?
From left: Perreaux Prisma 750 Monoblock Power Amplifier, Perreaux Prisma SM6 MkII Balanced Preamplifier.
I turned to the Perreaux web site to see what Perreaux had introduced since the mid-1980s. As I had been seduced by the top-of-the-line PMF5150 in 1989, in 2012 I was quickly attracted to the Prisma 750 monoblocks. The Polk SDA SRS1.2s could use up to 1,000 watts rms per channel. The combination of increased power and up-to-date components and engineering prompted me to begin looking for a used pair of Prisma 750s, which I found on Audiogon. They were demo units offered by a Perreaux dealer in the UK. The price was good, but they were set up for 240V, and although the seller would have arranged for conversion to 120V, I was concerned about the effect on warranty coverage.
Again, I turned to the Perreaux web site for help, and Managing Director Martin van Rooyen gave me the assistance I needed. Conversion to 240V would, indeed, present potential warranty problems in the US. Marty advised me not only to purchase the Prisma 750s in the US, but also simultaneously to upgrade our SM6 preamp to the current SM6 MKII preamp. Skeptical that I might be simply succumbing to the wiles of an expert salesman, I nevertheless accepted this recommendation. Then, we waited several weeks for the monoblocks to be built in New Zealand and shipped to the US distributor, but we were immediately able to pick up the new SM6 MKII preamp from the distributor.
Marty’s advice about the preamp was spot on. Once again, I cite Lisa’s testimony, rather than my own. She immediately heard a dramatic difference in sonic performance, even without the new Prisma 750s. Some, not all, the “muddle in the middle” was resolved, and the precision of transients and the clarity of highs were improved. These improvements heightened our anticipation of additional improvements when the monoblocks were installed.
We picked up the Prisma 750 monoblocks at the Perreaux distributor’s store, brought them home, and I promptly installed them. I called to Lisa, “Come listen to the inaugural CD on the monoblocks!” She came in the family room; I started the CD player, and we heard sound from the left channel and nothing from the right channel. Alarmed, I quickly switched off the system, and we heard a frightening “crack” from the right-channel monoblock. Fear and trembling!
Once again, I turned to the Perreaux web site for help. Marty and his technical staff did some research and told me that the SDA SRSs required common-ground amplifiers, but the Prisma 750s were non-common-ground design. I knew the SDA SRSs required common-ground amplifiers, but nothing in the Prisma 750 literature indicated that they were non-common-ground design. Marty put the issue to his technical staff, and they presented a solution to the problem. Interestingly, the solution joined the extraordinary interest in customers shared by Perreaux and Polk Audio.
The Perreaux technical staff had found the “Dreadnought” isolation transformer threads on the Polk Audio Forum and advised me not only to fabricate a Dreadnought amplifier interface to solve the incompatible grounding problem that Polk SDA owners had experienced many times before, but also directed me toward a supplier of the requisite toroidal isolation transformer to build the interface!
Clockwise from top-left: All parts for the Dreadnought build, the transformer and casework with Dynamat damping, finished Dreadnought front, installed Dreadnought rear.
Building the Dreadnought took some time, but the effort paid off. Once the Dreadnought amplifier interface was installed in the SDA interconnect between the right and left channel speakers, the performance of the Prisma 750s and of the entire system reached another higher level of performance. Not only did the Prisma 750s and the SDA SRS1.2s work together, they sang. Performance of the system improved on every dimension – but the “muddle in the middle” persisted, albeit to a lesser degree.
Perhaps, this would have been the end of the quest for a less tenacious spirit. The sound of our system had gone from a level that we had appreciated for over 20 years to a level of performance that we had only come to know because of our quest for better and better sound. Neither Lisa nor I consider ourselves experts or even accomplished audiophiles, but we have come to know what we like in sonic performance from stereo systems. At this stage our system delivered extraordinary sound with virtually all types of music – solo instrumentals and vocals, small ensembles including instrumentals and vocals, chamber orchestras and organ music. But, we just knew the “muddle in the middle” with orchestral music could still be improved.
Having been introduced to the Polk Audio Forum, for advice I turned to reading the abundant and generous contributions of knowledgeable participants in various threads. As they say on the Forum, I was induced to enter “the rabbit hole” of modifications to vintage SDA speakers that promised to bring them up to today’s standards of sonic performance.
Clockwise from top-left: SDA perfect-lay inductor parts, the SDA inductor installed, RD0194 tweeters and steel retaining ring, Black Hole 5 installed in cabinet, mid-range drivers with Dynamat applied, modified (top) and stock crossovers.
These modifications included completely rebuilding the crossovers with audio quality capacitors, resistors, and perfect-lay inductors; replacing the SDA inductors with perfect-lay inductors, replacing outdated tweeters (SL2000s) with updated RD0194 tweeters developed for the purpose by Polk, installing higher quality binding posts, applying Dynamat Xtreme to all driver and passive radiator baskets, applying Black Hole 5 in moderation to the interiors of the speaker cabinets behind the tweeters and midrange drivers, and installing “Larry’s rings” -- custom devices to secure the tweeters, drivers and passive radiators to the baffles. Trey Roseman at Vr3 Mods rebuilt the crossovers and binding post cups for me, and I completed the other modifications that required care and patience, but no technical skills.
Now, Lisa and I are enjoying extraordinary two-channel sound from a system that combines virtues of state-of-the-art contemporary electronics from Perreaux with unique characteristics of vintage Polk Audio SDA SRS1.2 speakers that have been brought into the 21st century with comprehensive modifications.
One afternoon, we experienced the joy of hearing profound improvement in our system as everything seemed to come together. Apparently, the “burn-in” time for the crossover modifications and new SDA inductors was over. The sound stage opened up, the sound became richer with highs lighter and airier and the bass deeper and tighter. The stereo imaging became focused with distinct placement on the sound stage. And, best of all, while the “muddle-in-the-middle” had not completely resolved itself, it had become far less noticeable.
Phillip's complete system, awaiting modification to cabinetry to complete the installation.
The quest is not yet completely over, but now we have only to complete extrinsic modifications to our cabinetry properly to house our components, but the important “stuff” – the primary factors affecting the sound – are set for now. Many thanks to the good folks at Perreaux Industries, to the many contributors to the Polk Audio Forum, and to Trey Roseman at Vr3 Mods for helping Lisa and me in our quest. It has been a challenge and a great pleasure that turned out well – very, very well.
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