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Positive Feedback ISSUE 42
march/april 2009


Pictorial Visit to Lotus Group USA/Prana Wire
by Ryan Coleman


I've known Joe Cohen, El Presidente and Dictator for Life of Lotus Group USA, for a few years now despite our having never met face to face. On a recent visit to San Francisco, CA, I took Joe up on an invitation to visit the global HQ of Lotus Group USA, as well as bit of listening to his reference system.

Factory Visit

Regardless of any personal camaraderie I have for Joe Cohen, I wouldn't have spent one red cent on the products Lotus Group imports if it weren't for the fact that they've blown me away with their performance and repeatedly reset my reference for what is possible in audio. Some of the lines that Lotus Group carries like Oyaide, are the de facto standard in AC connections; you will find more high-end power cords outfitted with Oyaide plugs than plugs from any other manufacturer, and the R-1 AC outlets are downright amazing and the best bang-for-buck upgrade I can recommend for any system.

However, Lotus Group also imports other brands, some of which are still trying to gain the widespread acceptance and praise that their performance deserves. One of them, Acoustic Revive, is a brand that I've extensive experience with, and I've simply fallen heads over heels for. I will always recall getting the RTP-4 AC conditioner + accompanying power cord in and thinking “there is no earthly way I'm paying my hard earned $ for a metal box with fairy dust inside." Well, proof was in the listening, and it was so audibly superior to anything else I've heard that I bought it, and so did the other serious audiophiles in my area who auditioned the RTP-4, all of whom ditched far more expensive active-AC conditioning products to upgrade to the passive Acoustic Revive RTP conditioner. I've also had the pleasure of auditioning (and buying) a few other Acoustic Revive products, such as the RGC-24 Ground Conditioner (indispensible on digital sources), the RR-77 low frequency generator, and the DSIX digital cable with outboard power supply (anyone with high dollar digital separates needs to audition this cable). Ultimately, Acoustic Revive products are tweaks, but in my experience the difference between a good system and a great one is how the system is optimized; in other words, has the system been 'tweaked' to extract maximum performance from its major parts? Well, Acoustic Revive products do just that and I can offer a universal “must audition" recommendation for all of them (though I dare say that the RTP-series of AC conditioners is so good that one could buy them without an audition).

Lotus Group also imports a few other lesser-known brands, to which I have no experience and cannot comment on their performance: Audio Replas (more AC and vibration control tweaks), Sound Mechanics (various footers and shelves for vibration control), and fo.Q (for vibration control of software, along with component shelving). For further information, I'd simply direct you to the importer's website, .

Oh, and Lotus Group also imports the Feastrex loudspeaker drivers, but I'll cover that later in this report.

Another lesser-known line for Lotus Group is Prana Wire Cables. Unlike all the other lines for Lotus Group, this is not an imported line, but one that's manufactured in house, and if my finances permitted I'd be the proud owner of. In my audiophile experience, I've auditioned speaker cables from Jorma, Transparent, Kubala-Sosna, Synergistic Research, Isoclean, and a host of other brands that I cannot recall. I can state that the Prana Wire Cosmos speaker cables were the top of the heap; they were simply the ideal combination of tonality, frequency extension, soundstaging, PRAT, and microdetail. Each cable in the above list did some things well, and some perhaps better than the others, but in this hobby it's always a choice of compromises and in my auditioning the Prana Cosmos had fewer compromises than any of its competitors.

The Prana Wire Cables are not adorned with huge esoteric networking boxes like the Transparent, they don't weigh a ton like the Kubala-Sosna cables, and they don't employ a few thousand dollars worth of Bybee devices like the Jorma (quick aside: Bybee devices can bring startling improvements in the proper application). So what is it about the Prana that makes them unique? Well, a few pictures with accompanying text can help address that.

The mad scientist Joe Cohen points out that all Prana Cabling gets a healthy burn-in via a Cable Cooker prior to shipment. The break-in of silver cabling was a lesson taught to me by the late Bob Crump (RIP), who had his TG Audio cables on a cable cooker for 30 days prior to shipment. Silver cables would be unlistenable without such treatment.

Here's the humidity-controlled chamber where the raw foils are cured with their micro-thin dielectric to prevent oxidation.

Above is a snapshot of Prana cables in various states of construction. As the photo shows, the conductors are heavily adorned with additional non-synthetic insulating materials, to provide spacing between the conductors and the shielding that will be layered on afterwards. The care by which a three quarters inch to four inch wide ribbon gets fashioned into a RCA, XLR or spade termination cannot be overstated. What I found interesting is that the Prana Wire speaker cables come closest to the ideal of 'no wire' as it does not employ any connectors or solder joints in the signal path (whereas the Prana interconnects do, though I understand an upgrade is offered where non-soldered connectors are available). I've little doubt that's one of the reasons I found it so exceptional, but certainly its only one parameter in the design that influences the performance.

Here's a balanced cable after shielding but before termination. Notice all those drain wires for the shielding. For those who believe unshielded cables sound better, Prana Wire Cables presents their disagreement.

This photo is of an almost-complete 26.5 foot (8 meter) Cosmos RCA cable. Joe Cohen says he's been building it for almost 4 months, and it's still not done. That statement is instructive. The Prana Wire Cables are not wound and spun off a machine, but hand-constructed by artisans. Yes, you pay a lot, and it takes a long time for them to be built, but no one rushed Michelangelo to finish the Sistine Chapel. Think of audio as art, and it will make a lot more sense.

Now, as an avowed DIYer and cheap bastard let me state unequivocally that there is no earthly way I could construct cables even remotely close to this standard of production. Modifying gear? Sure, that's easy—simply drop in more expensive parts and you've an instant upgrade. Building cables? No problem, anyone can do that. But assuming you can build cables that sound as good as someone who's perfected their technique and their material selection over decades is akin to someone taking a trip to the dentist and thinking they can be a dentist. There's a gap in knowledge that you don't see, but it will be obvious when you listen to the results.

Listening to the Lotus Reference System

I always find it comical to read someone's impressions of how 'X' component sounds when listening to a system. No one listens to a component; we can only listen to systems, and the only way to audition a component is to plug it in and out with various other components to try to ascertain its character.

With that background, my wife and I were invited back to Joe Cohen's home to have a little listening of his reference system: a very dated (but heavily modified) Teac CD Player, the H-Cat Preamplifier, Lamm ML2 amplifiers, home made speakers using the incomparable Feastrex drivers, with all cabling provided by Prana Wire and Acoustic Revive, and AC conditioning by Acoustic Revive. I've no prior experience with any of these components, so my comments will be directed to my general impressions; specific where possible.

Now, that's what I call tweaking! Talk about vibration control—I've never seen such a vibration-absorbing sandwich in all my years. This is as obsessive-compulsive as I have ever found, and frankly that's what getting maximum performance out of your system demands…an obsessive compulsive drive to optimize for AC, vibrations, and overall synergy.

Here we see the Acoustic Revive RTP-4, providing juice to one of the Lamm ML2 amplifiers. The RTP-series of conditioners is one of the only ones that I'd recommend for amplifiers as they are not active devices, having no active circuitry. They simply remove AC noise by passive means, and do not regulate or limit current from the wall in any way. In the above photo, we also see the Audio Replas IEC base at the far right, the Kemp Elektroniks SNS plug at the far left, and the Acoustic Revive Outlet Stabilizer in the center. I have no idea what the effect of these tweaks on the already-tweaky RTP-4 is, but I dare not try it myself …I haven't the budget for all these things!

The rear of the loudspeakers shows the Prana Wire Avatar speaker cable, along with an AC connection to the Feastrex driver. Feastrex drivers are unique in that do not use permanent magnets attached to the driver; as they are field coil drivers (no magnets), they require an outboard power supply to provide AC to magnetize the coil.

Talk about a mismatch: here we see the $32,000 MSRP, 5" Feastrex D5e Type II driver housed in a 15lb, $200 speaker cabinet. When I think about some of my favorite loudspeakers (Wilson and Rockport), I immediately think of their inert 200lb cabinets, and that's for the entry level models! Point being, I didn't expect much given how inadequate these cabinets appear to be to the casual eye.

Here's a close up of the Feastrex driver. These 5" Feastrex Drivers, the D5e Type II with phosphor bronze frames coated with traditional Japanese urushi lacquer, are near the top of the Feastrex range. On this particular driver, the plate and pole piece are made from Permandur the most magnetically permeable alloy available. Joe Cohen states that it is fiendishly difficult to machine and crazy expensive. For those looking for something more upscale, Feastrex also makes the even more expensive Type III field coil where the plate, pole piece and yoke (the entire magnetic structure other than the voice coil) are all made from Permandur.

So, given a brief rundown of the altogether unfamiliar components in a system I've never heard before, how did it sound? Well, I was able to listen to some well-engineered recordings I'm very familiar with (Jack Johnson, Ella and Louis), so can draw some distinctions from my reference rig.

I've always found that when you correct for vibration and AC, it pays dividends in imaging. From the sweet spot, the Lotus reference system absolutely floated, with no sense of room boundaries or speaker placement. And what was all the more puzzling about it was that this was despite $200 speaker cabinets. Another distinct impression I had was that the 5" Feastrex driven by a paltry 18 watts presented a shocking amount of bass depth, impact and dynamics. Did it match my reference Wilson Watt Puppies hooked up to 500 watt per channel monoblocks? No, but it was surprisingly close. Granted, no one is going to buy a single driver speaker so they can listen to AC/DC (just as one wouldn't buy multi-driver monkey coffins to listen to choral groups), but a good speaker should do all things well (and certain things exceptionally well). The Feastrex drivers will surprise with their frequency extension and dynamics, which I've no doubt could be extended further by a less-compromised cabinet (a folded horn might be ideal). Now, all this would be little more than a parlor trick if the system couldn't give a tonally accurate rendition of the midrange (which is where the music lives). Well, the Lotus reference system certainly did that, with an uncanny reflection of voices and instrument timbres. (Having communicated my impressions of the system's strengths and weaknesses, Joe informs me that he is hard at work on a cabinet that will take full advantage of the driver's capabilities and that will produce enough bass to satisfy any AC/DC fan. Look for it at RMAF or before.)

With lots to do on my trip to San Francisco, my time with Lotus Group drew to an all-too-quick end. But listening to the Feastrex-based reference system only confirmed what I already knew given my extensive experience with Acoustic Revive, Oyaide, and Prana: the ultra-artisan, esoteric products that Lotus Group imports and builds are reference-setting products that must be auditioned to be believed.