North Acoustics
Kitty Kat Revelator

Kitty_Pauduk_Lee_Right

Book Shelf Specific™ Reference Monitor

Welcome to the North Acoustics Web Site. We proudly present the Kitty Kat Revelator Near Wall Specific™ Reference Monitor, the world's first and only bookshelf-sized, reference level Near Wall Specific™ full range loudspeaker. North Acoustics' loudspeakers are designed by ear to be at their best when placed within three inches of a wall, are constructed with the finest cabinetry from hand picked veneers, and will look and sound wonderful in your listening room, recording studio or home theater.

"We believe that enduring quality is the most significant virtue of any product" - George E. Short III, May 1992

Image73

Above is the Kitty in African Pauduk by Lee Taylor and Co.

Design Goals

We conceived of the North Kitty Kat as something unique: a true reference level full range high efficiency bookshelf monitor. Kitty_Chery_Right

Those familiar with high end loudspeaker design will immediately recognize these as a family of competing goals. Never before has a full range monitor loudspeaker been built, neither has a reference level Near Wall Specific™ monitor. Both high efficiency and bass extension have always been the antitheses of a bookshelf-sized loudspeaker. In the Kitty Kat Revelator, we have successfully overcome these challenges.

The most difficult placement position to get great sound in any listening room is also the most convenient: a loudspeaker placed on a stand or bookshelf, with the back of the loudspeaker only a couple of inches from the wall. The aesthetic advantages of near wall placement are obvious: a loudspeaker that takes up less room translates to increased living space; a loudspeaker in a bookcase matches best with other elements in the room; and our informal survey indicates the quickest route to "spouse acceptance factor" is to place the loudspeaker where it blends in with the rest of the room.

However, most conventional "bookshelf"-type loudspeakers are actually designed to be placed on a stand in the acoustic free-field; that is, with the rear of the loudspeaker a minimum of two feet from the back wall and its face three to four feet out. Conventional loudspeakers sound best there because with slight changes in placement, one can optimize the room interactions to minimize early reflections and "tune" the bass to the room. The difficulty of course is that the best sounding loudspeaker position may be far enough into the room where they begin to infringe on traffic patterns or become visually obtrusive.

Kitty American Cherry Veneer

The central design element of North Acoustics' Kitty Kat Revelator Near Wall Specific™ loudspeaker family is based on a fresh new look at the performance vs. placement issue: by fixing one boundary condition and optimizing the loudspeaker’s performance for that boundary condition, the owner then has considerable placement freedom as long as the first boundary condition is kept. Specifically, the rear of the North Acoustics' Kitty Kat Revelator Near Wall Specific™ loudspeakers must be between two and eight inches of a wall. In this position, the presence of the wall directly behind the loudspeaker reinforces the output of the rear-mounted port by coupling of the woofer and port with the room, enhancing the loudspeaker's ability to pressurize the room and resulting in a smoother bass response over a wider frequency range. Despite its compact size, by taking maximum advantage of room placement the Kitty Kat Revelator loudspeaker system becomes both more amplifier-friendly and exhibits a smoother, deeper bass quality throughout the listening area.

Even though the Kitties have an explosive low end, they are very clean even at high volume levels while the midbass exhibits the resolution one gets only from a smaller woofer. The midrange is smooth and blends effortlessly into a sweet top end that is flat to 20kHz, but without any hint of sibilant emphasis. The harmonic balance is reminiscent of a much larger speaker, but a little leaner and with a lot more speed.

The North Acoustics' Kitty Kat Revelator Near Wall Specific™ loudspeakers are not particular about horizontal spacing or vertical placement. Whether resting atop 24" stands or placed high on a bookshelf, the Kitties will disappear into a spacious, convincing soundstage that appears behind the wall they are placed against. The Kitties are also magnetically shielded, making these fine loudspeakers equally suited for monitor, recording studio and multi-channel home theater applications.

 

Driver ComplementD28_A

The Kitty Kat is built around the unique North D28-III Silk dome tweeter, made specially for North Acoustics with our exclusive full Faraday Sleeve™ technology, mated with a custom version of the legendary Scan Speak Revelator 5.5" woofer, widely considered the most naturally musical small woofer ever built.

The North D28 silk dome tweeter is custom made for North Acoustics by hand, and exhibits a low fundamental resonance and more excursion capability than many midrange drivers, making it very well suited to mate with the 5 " woofer at the 1651Hz crossover frequency. Also, because it is constructed with a Faraday cap that extends above and below the voice coil’s maximum excursion, the D28 has a gently rising response with just a touch of sparkle at the very top end. The North D28 also exhibits intermodulation and harmonic distortion an order of magnitude lower than any conventional tweeter on the market.

A reference quality loudspeaker deserves a reference quality woofer. There are a lot of very good woofers out there, but we were looking for a driver could deliver both explosive bass in a modestly sized cabinet and a midrange that is super clean, and if it errs at all it must be on the side of being forgiving. Also because this is a Near Wall Specific loudspeaker design, no baffle diffraction step compensation would be required, therefore we needed a driver with relatively flat frequency response though the midrange. In the end, we were not able to find the exact woofer we required, but were able to fabricate a custom version of the Scan Speak 15W Revelator sliced-paper-cone bass driver.

This is a very special driver. Both the cone and dust cap are sliced in a rotated radial pattern, then rebonded with a damped adhesive. The slices and damping create a constantly varying mechanical impedance mis-match throughout the cone body, eliminating the possibility of standing waves between the voice coil and surround. This also allowed Scan-Speak to use a much stiffer cone than would normally be acceptable, pushing the cone’s fundamental break up mode well beyond its operating bandwidth. Terminating the cone with Scan-Speak’s unique variable thickness surround allows complete adsorption of waves travelling through the cone body. This combined with an optimized voice coil inductance result in a driver with remarkably flat frequency response, requiring a very simple low pass crossover topology with a minimum of response shaping circuitry.

15WSCScan Speak Revelator Woofer
Shown here with optional magnetic shield

The combination is dynamite. With a profile barely larger than one square foot, the Kitty Kat recreates a soundstage with exceptional height, width and depth, then vanishes within it. The voicing is absolutely perfect, and the Kitty Kats can purr like a kitten, growl like a tiger or roar like a lion.

 

 Frequency Response and Voicing Goals

The key to designing a great sounding loudspeaker is in its voicing. Simply put, voicing is the process of balancing a loudspeakers’ low end strength, mid-bass richness, midrange liquidity and top end sparkle such that the system sounds both natural and involving. Measurements are not particularly useful when it comes to voicing; it can only be done by ear. One can easily hear a small fault in voicing in 30 seconds of casual listening, but it takes months of serious listening and design time to get it right.

The North D28III tweeter is responsible for the top end, and here is voiced to be ruler flat 6kHz with just a tiny touch of sparkle in the top octave. A little sparkle here makes the overall sound of the system be more intimate on serious listening and faster when listening casually. Also because the slight rise in frequency response is built into the dome design, the crossover design is simplified which allows a straighter signal path and facilitates getting the most out of the highest quality crossover components.

Throughout the midrange, the Kitty Kat measures almost ruler flat and what tiny variations it exhibits are dips. Dips are always better than peaks, as a midrange with dips will err on the side of forgiving, where as those with peaks will err on the side of over-emphasis. Other than a tiny wiggle though the classic BBC "dip" region centered at 3kHz, from 200Hz to 20kHz the Kitty Kat measures an amazing 87dB +1, -1.5dB. This is a window of over six and a half octaves.

Based on independent measurements, the Scan Speak 15W woofer also exhibits the lowest harmonic distortion of any mid-woofer on the market, and it is this absence of distortion which allows the driver to be both revealing and forgiving at the same time.

We weren't shy with the low end, and the Kitty Kats are voiced with a bit of slam at the bottom. There are two reasons for this: 1) the Kitty Kat has very little output below 30 Hz, so voicing the loudspeaker without slam would make it sound lean overall. Therefore due to the absence of output in the lower half of the bottom octave, a little extra presence the half-octave above it balances the overall presentation, and in fact the Kitty Kat sounds like it goes a lot deeper than it does; 2) subjectively, on most music, slam factor is way for fun to listen to than the absence of slam factor.

Even with a box volume of only 0.5 cubic foot, the Kitty Kat is capable of extraordinary bass performance with solid extension well into the 30's. Dynamics are effortless, but with a wealth of textural complexity and timbral accuracy that most larger loudspeakers placed well into the room can not match.

Measured Performance

The Kitty Kat’s frequency response is shown below. The low frequency curves are taken with the close-mic technique, with the port output scaled via its area ratio to mate correctly with the woofer output. The midrange on up is measured at two meters under anechoic conditions with the exception of the rear wall, which is 3" behind the rear of the loudspeaker. The measurement is set up this way to properly reflect how the loudspeaker system would test in the actual listening room.

Kitty_Freq_Spread

North Acoustics Kitty Kat Frequency Response Spread

As described above, the Kitty Kat measures 38Hz to beyond 20kHz +-2db, and through the critical midrange is +1, -1.5dB. System sensitivity is 87dB, very high for a true bookshelf monitor.

The antiphase null is an excellent –24dB, indicating nearly perfect driver integration throughout the crossover transition region.

Big_Kat_Z

North Acoustics Kitty Kat Impedance Spread

The Kitty Kat’s input impedance is shown above, both with and without the (optional) impedance twister circuit. Without the twister, the system has impedance minimums of about 3.5 Ohms at 300Hz and 5kHz, while the impedance maximums are evident bracketing the 37Hz port tuning frequency and near the crossover frequency. All told, the Kitty Kat without the twister is a very easy load for most modestly powered transistor amplifiers to drive, and 15 Watts minimum is recommended.

With the twister in place, from 300Hz up the impedance measures 5 Ohms +- 1.5 Ohm, which is ultra-stable. This is a better match for valve electronics or transistor amplification that is picky about the loudspeaker load.

Sound Quality

The most striking aspect of the Kitty Kat’s sound quality is how riveting it can be. In fact, even when outside the listening room, the Kitty Kat’s have such a robust bass presentation and rich, wealthy midrange that it actually draws one in just to get a closer listen.

This loudspeaker even succeeds at this with older recording; Led Zeppelin’s "Kashmir" (from Physical Graffiti, Swan Song SS200-2) not only revealed layers of material but also communicated that the Led Zep boys were getting along very well at the time and had a great time recording the album. Similarly, the Beatles remastered recording of Rubber Soul draws one in for a listen because it sounds so naturally rhythmic and involving.

Sitting down with the Kitty Kats, listening seriously, one is immediately taken by its absence of distortion throughout the midrange and top end. It is a unique quality that the midrange can be fantastically detailed and revealing without being even remotely analytical. This contributes to the loudspeakers’ ability to be involving while it is still relaxing.

Janis Ian "Where the Silence Falls" (Putumayo 128-2) for example, the bass drums have extremely dynamic slams, yet the singer’s voice stays liquid, focussed dead center and well above and behind the loudspeaker positions. Way back at the far left edge of the soundstage, one can hear a rhythm guitar play about three measures and then vanish.

Kitty_C_Sapele_Lee-Taylor
Kitty Kat Rev/Rev Center Channel Sapele Veneer
Photograph courtesy of Lee Taylor and Co.

Rebecca Pidgeon performing "The Word Around Town" (Chesky CHE10), one is immediately taken not only by the vocal clarity but also the touch of humor that is easily communicated.

Lower down in frequency, Don Williams "I'm Just a Country Boy", the Kitty Kat also shines. Vocal inflections are carried with remarkable clarity and immediacy and a complete absence of coloration, and with just the right amount of robustness.

Voicing is definitely full range in nature, and even though the Kitty Kats 3dB down point is only 35Hz, their 10dB down point measures a very low 28 Hz and they sound like they are a much much larger loudspeaker. These Kitty’s can rock and roll. Beck's "Scarecrow" (Guerro Interscape B0003481), for example, the driving bass guitar effortlessly fills the room while Beck’s vocals are clear as day.

For those looking for a reference quality near-wall monitor that is capable of recording studio resolution while still being forgiving, the North Kitty Kat is their best choice.

Two_Kittys_Small_Dark_Cloth
Kitties  by Lee Taylor and Co.
 Naked Silver Face Plate no longer available.

 

Fully Assembled Kitties from North AcousticsKitty_Chery_Right

Kitty Kat Revelator loudspeaker system
(fully assembled, bi-wired, in American Cherry or Maple) ...$2499.00/pair Retired 2015

 

Kat Revelator Center Channel
(fully assembled, bi-wired, in American Cherry or Maple) ...$1499.00 each  Retired 2015

 

Kitty Kat Kits:

Kitty Kat Revelator Kit
(includes broken in, tested and matched drivers, fully assembled crossovers, all connectors, Dacron,
port tube, binding posts....everything except the wood)…. $1,699.00/pair   Retired 2015

(Scan Speak D2905/9900 Revelator Tweeter Upgrade add $329/pair)
 

 

Kat Rev/Rev Center Channel Kit
(includes broken in, tested and matched drivers, fully assembled crossovers, all connectors, Dacron, port tube, binding posts....everything except the wood)…. $1,199.00/each Rev/Rev $1429/each  Retired 2015

Center_Cherry_Small

 

 

 

Designer's Comments

Bending or breaking all of the rules made the Kitty Kat a very fun loudspeaker to design.

The crossover design was a bit of work. The modified woofer has a very powerful bottom end, and to keep it from overpowering the rest of the spectrum an absolute minimum of reactance was required until just below the crossover frequency. The best way I can describe the finished low pass network is that it uses a very gentle application of response shaping circuitry to get the required slopes.Kitty_Crossover_Small

Because the North D28 tweeter was designed with a very slight rise at the top end, the high pass network is a straight forward second order with only a single reactive element in the signal path. For this we use a full cascade-bypassed Crescendo film-foil capacitor bank.

All of this said, the most striking aspect of the Kitty Kat is its voicing. The bass goes so deep and it is so dynamic that it is hard to believe it is coming out of this little box. It just effortlessly energizes the room.

The midrange is perfectly balanced and the transition to the tweeter is seamless. Vocal clarity is simply stunning. All told, the Kitty Kat's have a sense of continuity about their sound that I have rarely heard in loudspeakers at any price, and never when stuffed practically against the wall.

North Kitty Kat tweeter crossover network

When we showed the Kitty Kats at the New York Vacuum Tube Valley show in May of 2006, we were playing them with a Consonance CD player and integrated amplifier driven through Igor Kuznetsoff's   cables (simply the best interconnects I have ever heard, and in my opinion the highlight of the show). Next to them, we had the .A.R.T. Metros with Usher and Belles electronics. Granted, the Kitty Kats operating on about $2000 in equipment was not as good as the Metro/Usher/Belles set up (at nearly six times the price), but in my opinion the little Kitty Kats held their own impressively. I could have gone with only with the Kitty Kats and still would have considered the show a great success. Kitty_Maple_Brown

Kitty kat in American Maple

Since the NY show, we have played the Kitty Kats to several individuals whom visited the North Creek Showroom, and opinion is unanimous that it is the best near-wall loudspeaker any of us has ever heard.

Listener's Comments:

 Hi George,

The North Acoustics Kitty Kat Revelator had my heart in the first few seconds of listening. This monitor had a large soundstage, excellent resolution, unbelievable transparency, and much more bass than I expected from a monitor. I heard no mistakes. The Kitty Kat sound had the quality of realness which it delivered effortlessly with authority; yet, there was also delicacy as if an artist were at work on the portrait of a stunning beauty.

The Kitty Kats are superb and easily the best monitors I have ever heard. The decision to buy them is a no-brainer.

Sincerely,
John F., Maryland

 

The Kitty Kats are amazing speakers. Their voicing is exactly what we've come to expect from George: they reproduce all kinds of music with precise detail and generate a sense of space around each instrument. And they seem to do this effortlessly. But what surprised me (in fact, shocked me) was the bass that these little speakers exhibit: not a hint of muddiness, very tight and controlled and plenty of it. Nothing short of remarkable.

Can't wait to set them up in my office.

Martin S., Ontario

 

Hi George,

I just wanted to thank you again for your hospitality last Sunday - I really
enjoyed our visit, and listening to the speakers you've created was a
delight.

The Kitty Kats were really beautiful in their even frequency response and
generally uncoloured sound - the bottom end was surprisingly full and warm,
and the way that they filled the room was impressive. The Metros were truly
stunning - your development of ribbon technology is remarkably creative, and
the results are astounding - I played a lot of different cd's from a lot of
different musical languages and sonic approaches, and the imaging, clarity
and warmth remained consistent throughout - it was a terrific experience.

Sound is such a subjective area, and there's so much voodoo mixed in with
the physics - i really enjoy your approach to the whole process, and my own
sensibilities definitely align with what you're going for...

Thanks again, and

Best regards,

Konathan G., Toronto

p.s. the huevos rancheros rocked, also.

 

 

George and Lee,

I just want to say that I am really enjoying the total Kitty Kat package. The quality and build of the cabinets were top notch. Especially since my wife liked the veneer.... Lee you were right on the grills, you are simple are not going to get any reflections from the grills. I am glad that I paid a little extra from them.

The quality of music coming out of the Kitty Kats is astounding. I have a pretty decent home theater set up with tower mains speakers. The tower speakers is a 4 way design with Vifa ring radiator tweeter, one 4" midrange, four 5.25" woofers, and 8" 350 watt powered woofer. I also use the tower mains for all of my 2 channel music listening. Well, my goal for the Kitty Kats is to use them for my main floor leaving room. Ideally, I was hoping for the Kitty Kats to produce the same level of dynamic sound but with better quality compared to my HT main tower speakers. I knew matching the tower speakers as far as dynamics is concerned was going to be a tall order. But I was surprised.

Over the weekend, I did some A/B music testing with the Kitty Kats and my main towers. As far as quality, the Kitty Kats came out on top. It was kind of weird, the Kitty Kats had a wide sound stage but the sound was very neutral. I can not think of any other words to describe it. Compared to my tower speakers, the towers also have a wide soundstage but the sound seemed to have some sort of surround effect. This surround effect made the music reproduction sound slightly colored. I did not notice this with the Kitty Kats. I guess this would make the towers better for HT rather than 2 channel music listening.

The the next major difference I notice was the bass response. With the powered woofers on in the towers, the bass coming from the Kitty Kats were not as loud but it was very close. This is pretty impressive for one 5.5" driver. The tower speakers I own can also be purchased without the powered woofer. So I shut off the woofers and compared the bass response again. This is were the Kitty Kats really shined. There was no comparison, my towers without the powered woofers could not compete. Even my wife noticed this.

I am so excited about the potential of these Kitty Kats. So much so that I am know looking to piece together a 2 channel music system. This is something I was not really considering on doing in the past.

Thank you George and Lee for all the help.

Regards,

Akono G

 

George,

... the Kitty Kats are simply awesome with the Nuforce reference amps and a ARC vintage SP6 preamp....they just blow me away. I hear the music, I put on my back brace and I just dance. Thank you so very much for your wonderful contributions to audio.

I hope you continue to sell some very high end speakers as I am definitely a convert and NCMS evangelist.

Robert H.,

Troy, Al.

 

> Hello,

> I purchased a used pair of Kitty Kat speakers from you about 5 months ago

> (the ones you had on your specials page). Happy to report I finally got

> them up and running in the mastering room at my studio facility an San

> Jose, ca. and I am very impressed with them! They sound great! I'll send

> you some pictures of the new mastering room soon.

> Just wanted to say thank you!

>

> Steven G.

Kitty_Production_1

First Kitty Kat Production Run

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