Since a long time, I have known exactly my priorities as a listener. Also, I had been intimately familiar with the many strengths of my monitor/subwoofer speaker system, but also with its weaknesses, especially since I had very regular exposure to other systems, most often to that of my friend Ian (WBF member Madfloyd).
So I decided that a new speaker (system) would have to improve on the weaknesses of my monitor/subwoofer speaker system while retaining all of its considerable strengths. I was not willing to compromise on that. And it would have to be priced at a level that I could afford. Based on prior experience, I thought that speakers which could do that would be far more expensive than these PranaFidelity speakers and probably would not quite fit into my room. More than probably many others, I am extremely sensitive to “boxy” sound, especially in the midrange, for example with chestiness of voices. Unfavorable speaker/room boundary interactions can also elicit this boxiness which I cannot stand, and this can be a problem especially with too large speakers for a too small room. Mine is relatively narrow at 12 feet (while length is rather favorable at 24 feet).
I therefore did not expect to change my speaker system when I visited T.H.E. Show in Southern California in June. Yet then my friend Jeff (WBF member jeff1225), his father and I visited the PranaFidelity room, with the Dhyana speakers. Steven, the designer of PranaFidelity, played some Muddy Waters from Folk Singer on vinyl and it blew me away. It had the same explosive macro- and micro-dynamics on voice and steel-stringed acoustic guitars that I was used to at home, and the timbre as well as fine detail were great. We also heard a track from vinyl with gutsy and full-bodied sounding saxophone sound that I was very impressed by. This system, as one or two others at the show, also belied the idea that class D amplification, here with PranaFidelity purna/ca preamp and purna/ma amp, cannot sound good; instead of a gray and grainy sound as I had heard from class D in the past, the sound was natural and colorful – obviously, class D now had matured (Steven himself would later point out that until recently class D just didn’t sound good). All three of us agreed that this was a great sounding room, and after Jeff and his father had left to see other rooms as well, I remained glued to my seat and was treated, along with other visitors, to one of the most dynamic, explosive sounding drum solos I had heard from any system. I knew I had to explore these speakers more, and Steven invited me to return after 5 pm when the session had closed and bring my own CDs. I tried a Beethoven string quartet and was treated to basically the same micro-detail and micro-dynamics as at home, but with probably better sounding cello and a completely effortless sound at a good volume. A Haydn piano sonata sounded great as well, and the piano sounded more of one cloth from low to high register than at home with monitors/subs, even though there it had been no slouch either. I then knew this was something special. I now was thinking about buying the speakers.
I decided that I had to test drive these speakers with all my CDs that I had brought, spanning many genres. This is what I did the next day, Sunday, instead of listening to some other rooms as I had planned to. Obviously, given the presence of all the other visitors to the room I could not do that in one go, but strewn over the sessions I managed to get in all my test tracks, which performed great and, also with all the other material that Steven played – from vinyl, CD or tape – over and over I was sold on the effortless sound, natural tone, outspoken dynamics and high resolution. Also Black Sabbath War Pigs from my Paranoid CD sounded great, with good weight on the drums that I did not quite have at home, as well as a cleaner rendition of Ozzy’s voice, and with everything else just as good sounding as I had been used to. Funny, after I had put on the song and cranked up the volume to a good level, the room was filling up, with one guy next to me playing air drum, and by the end of the song after 7 minutes it was packed with people, sitting and standing. Obviously, people hunger to hear some good rock at a show (exhibitors, take note).
At the end of it all I was sold and decided to order the speakers. They did all I wanted, sharing all the strengths of my monitor/sub system and greatly improving upon its weaknesses. Also, the narrow width of the speakers (the front baffle is just 10 inches wide, slightly smaller than width at the body) as well as the adjustability of the bass ports gave me enough confidence that they very likely would work in my medium-sized, rather narrow room, both in terms of avoiding speaker/room boundary colorations and of sonically disappearing in the room. Importantly, based on Steven’s assurance, backed up by comforting technical data that he provided on impedance and phase angle (listed above), I also gained confidence that my Octave tube amp would be able to drive the speakers well. Steven would be proven to be right, see below.
The Speaker
Retail price/pair: $ 19,500
Dimensions in mm: 1219 x 278 x 455 mm (H x W x D)
Dimensions in feet/inch: 4.0 feet x 10.9 inch x 17.9 inch (H x W x D)
weight: 45 kg (100 pounds)
Below data are largely based on personal communication by Steven Norber, the designer.
The Pranafidelity Dhyana is a two-way multi-driver speaker in a quasi-line array of the four 6-inch mid/woofers where all these drivers receive the same signal via the crossover. The cabinet is dual-ported.
The mid/woofer is made to Steven’s specs by SB Acoustics with proprietary damped and coated paper cones. The tweeter is a textile (soft) dome with dual neodymium magnets. The crossover is a mixed slope network (asymmetrical network combining different order slopes) with a high-order acoustic roll-off. This takes into account the natural roll-off of a driver (low pass and high pass), and when coupled to a crossover the combined result is: a steeper slope than the network specifications.
The cabinet is Baltic birch throughout. There is elaborate internal bracing, with proportions according to ratios of the Fibonacci series (see below). The front baffle material is a high-density, resin impregnated wood product.
The nominal sensitivity is specified at 88.5 dB/1 W/1 meter. Under those conditions (1 watt/1meter/88.5 dB) the distortion was measured at <1% THD, 2nd through 5th harmonics, from 25 Hz onward, which is very low distortion for a speaker. Nominal impedance is 8 Ohm, with a dip at 172 Hz to a still high minimum of 6.1 Ohm. Together with shallow and small variations in phase angle the speakers present a minimally reactive nominal 8 Ohm impedance.
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I asked Steven why the mid/woofers were only 6 inches in diameter. His answer: “Speed”. While 6 inches per driver may not seem much, the combined effective piston area (driver cone area) of the four identical mid/woofers handily surpasses that of 10-inch drivers and is very close that of a 12-inch driver for midrange and for bass. That is quite a bit of surface area for those frequency ranges!
The fact that the cabinet is made from wood avoids driving up the price by expensive metal machining as with other speakers. The sonic result as discussed below shows that the cabinet, with its elaborate internal bracing, is inert to a degree that allows for high resolution of detail, without blurring by resonances.
The nominal sensitivity of 88.5 dB/1 W/1 meter seems a bit low, yet there is no need to be worried by that number. In practice the sensitivity turns out quite differently, as discussed below.
The minimally reactive nominal 8 Ohm impedance is very friendly to tube amps.
The Speaker
