February 2012


World Premiere!
ModWright Instruments KWA 150 Signature Edition Amplifier
Calling out the big boys.
Review By Phil Gold

  There seems to be a glut of really high end stereo power amplifiers. Five figures will get you a Pass Labs XA100.5 ($16,500), an Esoteric A-100 ($19,000), a Soulution 710 ($45,000), a BAlabo BP-1 Mk.II ($77,500), a Simaudio Moon Evolution W-8 ($15,000), a Luxman M800-A ($19,000) or an ARC Reference 110 ($10,995). And that is just the single chassis stereo power amplifiers top rated this year by various print magazines!

Then there the power amps split into two monoblocks. In some cases the single chassis would be too big and heavy to move, or the designer may wish to create greater isolation for each channel than is possible in a single case, or the power draw is too much for a single power cable. Users may also prefer to position a monoblock near each speaker, keeping the speaker cables as short as possible. So you can add to this list the Classé CA-M600 ($14,000), Bryston 28B ($19,200), Cary 211FE ($20,000), Spectral DMA-360 MkII ($20,000),  Classé Omega ($35,000), conrad-johnson ART ($35,000), Ayon Vulcan II ($40,000), VTL Siegfried ($50,000), Soulution 700 ($130,000), Lamm ML3 Signature ($139,290), Constellation Hercules ($140,000), Ayre MX-5 ($18,500), Electrocompaniet AW400 ($12,500), Luxman B-1000f ($55,000), mbl Reference 9007 ($35,423).

We're not quite finished. Musical Fidelity's Titan ($30,000) is a two chassis stereo design but one chassis has the amplification, the other has the power supply. There are also outstanding amps for D'Agostino, Krell, Accuphase and others that may not have been reviewed yet by the print magazines, and some worthy competitors coming in below the $10,000 mark, like the Parasound JC1 monoblocks, Plinius SB-301 ($9045), Aesthetics Atlas ($8000), Boulder 860 ($9000) and Simaudio Moon Evolution W-7 ($9500).

From the price tag, you might think the ModWright KWA 150 Signature Edition ($8495 or a $2000 upgrade from your KWA 150) is competing head on with this last group but I'm guessing this is a no holds barred effort from ModWright and you can and should audition it against all comers.

Let us start from the beginning. ModWright is not a name you would necessarily put up there against Pass Labs, Classé or Cary. It just hasn't been around long enough to establish that kind of reputation in the industry, and in the early years it did not offer components designed and built in house. Here's a message from company president Dan Wright, taken from the website:

ModWright was founded in 2000 as a company producing modifications to digital products. The mods were cost-effective, yet high quality alternative to the audio enthusiast. Born from this, our Truth series of modifications, utilizing tube analog stages, won ModWright worldwide acclaim and led us to the next step: building our own equipment.

The 9.0 series of preamplifiers was introduced in 2003, continuing the trend of high performance audio with an emphasis on quality and value. This included a phono preamplifier and later a balanced tube linestage, the LS 36.5. In 2009 we proudly released the KWA 150 amplifier to round out a complete ModWright Electronics system.

We have continued on this path of building high quality and high value audio equipment, designed to provide the most natural and satisfying musical experience. We pride ourselves as much on the quality of our work as on our level of service and customer satisfaction. As founder of ModWright Instruments, I strive to maintain the message within our mission statement: Elegance. Simplicity. Truth.

To bring this up to date on the power amp side, ModWright added a smaller integrated amp, the KWA 100, which is also available in a Special Edition, and are just introducing their first integrated amp, the KWI 200. Let us look first at the KWA 150 ($6995). It puts out 150 wpc into an 8 Ohm load, or 275 wpc into 4 Ohm. It is a solid-state amplifier in a beautiful and distinctive chassis that weighs 84 lbs. It offers two bias options, runs fully balanced, with balanced XLR and unbalanced RCA inputs, uses top quality Cardas connectors and features a regulated power supply for the input stage. The single voltage gain stage was designed by Alan Kimmel. The amp is transformer coupled at the balanced inputs then direct coupled throughout, fully dual mono, fully-differential and uses no global feedback. It is designed and built in the United States.

ModWright offer the option of using the KWA 150 in bridged mode. There are separate binding posts for bridged mode mono output and the input should be connected to the left channel only. Note that operating in bridged mode increases the power per channel from 150 watts to 450 watts at 8 Ohms, enough to drive pretty much anything out there to peak volumes.

  Upgraded Lundahl input transformers with larger signal capacity.

  Revised input circuitry offering lower distortion and noise.

  Cryo-treated solid core ultra-pure input wiring and 12 GA Cardas litz output signal wire to the binding posts.

  Higher output current capacity and speed through a revised power supply.

An amplifier like this deserves the best partnering equipment if we are to see just how good it is. The EMM Labs XDS1 is the best digital source I have heard and a perfect match for the superb EMM Labs Pre 2 preamplifier. I used both the Totem Metal speaker, a very demanding animal capable of superb bass extension, and the YG Carmel, the most accurate speaker I have heard in my room. A Nordost Thor and Nordost Valhalla cabling complete the picture, creating a system capable of revealing layers of detail and pinpoint imaging along with superb dynamics.

The KWA SE has some unusual aspects. To power it up you press the flush MW logo in the centre of the front panel and wait a minute while the blue lighting flashes. You can start listening at once but I'd advise you to let it reach its working temperature first. There are some controls on the back panel that I should cover. The High Bias switch should be on at all times for best performance, but you can flip it off rather than powering down if you want to save electricity but want to avoid a long warm up. In High Bias mode, the amp stays in Class A for more of its operating range and that translates to a richer more musical sound. The mono/stereo toggle is mostly useful for bridged mode and I never touched it. I also left the LED switch in the on position. Not only does it illuminate the ModWright logo on the front panel, it also bathes the much larger logo in the top panel in the same blue light -- cool. The ground switch is one I did make use of. The standard position is down, tying the signal ground to chassis and earth ground. In my system that left a slight hum which was eliminated in the up position which decouples the signal ground from the chassis and earth ground, which are always tied together. Kudos to ModWright for offering this flexibility.

The switches on a power amp are pretty much set and forget. Unless you're a reviewer like me you will likely only use the power switch at the front or the low bias/high bias switch at the back between listening sessions. All that really matters is the reliability, the look and the sound. Now there are a lot of amplifiers which can produce excellent sound with some easy to drive speakers, but to be able to fully drive a wide range of speakers is a much less common phenomenon. Many tube amplifiers for example cannot adequately control the deep bass on some powerful speakers. With mega-buck amplifiers you are often buying into very elaborate stiff power supplies capable of delivering high instantaneous and sustained current to inefficient or demanding speakers such as electrostatic designs. Although rated at a mere 150 wpc into 8 Ohms, this ModWright amp will take such difficult loads in its stride and extract the full bass performance that the best modern speakers can produce. It never showed the slightest signs of strain with the Carmel, or the much more demanding Totem Metal speakers that had proved a challenge for the nominally far more powerful Bryston 4BSST² (300 wpc into 8Ω). For those very few systems that need even greater output, ModWright recommends using one KWA 150 Signature Edition per channel in bridged mode, which triples the peak wattage available.

So let us take a look at the three criteria on my list...

The Reliability
This comes from a conservative design which never puts undue stress on any of its components, the selection of high quality parts, build quality and protection circuitry. One look inside the amp will be enough to convince anyone of the build quality. The 5 year warranty is also a good sign. ModWright uses 12 ThermalTrak bipolar output transistors per channel. These incorporate a diode to regulate the bias automatically as the temperature changes. This allows a simpler circuit and that is usually a plus for reliability. While most manufacturers will select power supply capacitors off the shelf, ModWright roll their own M-Series Truth and T-Series Truth Capacitors. The M-Series Capacitors are made with a proprietary oil-impregnated metalized polypropylene dielectric with pure copper tinned leads. The T-Series Capacitors are made with the highest grade of ultra-pure Teflon film and tin foil. The KWA 150 uses four large caps per channel while the Signature Edition uses 16 smaller devices per channel. These are housed eight caps per PCB with two stacked PCBs per channel. This allows for a greater overall total capacitance and lower ESR (Equivalent Series Resistance or power supply impedance). That should translate into greater speed, transparency and detail. Caps are the most likely components to fail in any amp, so building your own is a good way to take control of this quality issue at the source. Transformer coupling on the inputs avoids any possibility of a DC bias entering the amp, which can be destructive to a powerful amplifier. The internal wiring and the external sockets are top of the line items from Cardas Audio, a byword for quality in this industry. The heat sinks are massive and ModWright claims they are oversized. Certainly I couldn't get them too hot to touch no matter how hard I worked the amp. A soft start is provided (about sixty seconds of silence) so there will be no sudden rush of current at start up to overload the device, and full protection circuitry is delivered outside the signal path so as not to impair the sound.

The Look
I won't dwell on this aspect, since what may seem beautiful to me might be plug ugly to you. Look at the pictures and make up your own mind. But not only do I really like the look, I'm also very impressed with the fit and finish which I'm certain would satisfy even elevated Japanese standards. It's a big beast to be sure, but no bigger than it has to be to hold all the components, and it is slightly less deep than many rival designs which makes it a better match for my custom cabinetry. I very much like the silver finish but if you prefer black, it's yours for the asking.

The Sound
Not a great deal to say here, since the ModWright imposes very little of itself on the signal. Dan Wright is known to many for his work with tubes, but while he prefers them for low level applications such as preamplifiers, he feels that for a power amplifier, transistors are optimal. So none of that tube warmth (which may be the result of even ordered distortions) here, but we do have a ruler-flat frequency response over a very wide bandwidth. The best qualities of the tube sound that we admire so much is the result of vanishingly low odd-ordered distortion, massive dynamic range and very high low-level linearity and detail. With the right design you can get all this from transistors too, and Dan is not the only guy to believe this and attempt to achieve it. I'm preparing a group test of high quality headphone amps and one of them, the Graham Slee Solo Ultralinear is a deliberate attempt to emulate a tube sound from transistors. As designers learn more how to measure and tame the distortions that power transistors can produce, and as manufacturers of transistors make design advances of their own, it becomes harder and harder to tell one type of amp from the other in any serious candidate for consideration. I certainly make no allowances in my review. It either sounds right or it doesn't, and I don't care how you get there.

What I can say is that the sound field is spacious, musical, tonally accurate and extremely dynamic. It doesn't feel bass heavy or bright, but wind and brass instruments exhibit their full quota of air, while the deep bass is both tuneful and full in level. What's special about the bass is not the amount of it – the response is flat after all -- but how agile it is. The treble neither spits at you nor become tiring after extended listening but instead is open, detailed and natural. The frequencies in between are rarely an issue in amps of this stature, but what is remarkable is how the sound is consistent across a vast array of frequencies and dynamic levels. Louder is the same only more so, softer does not imperil the musical drive. In fact all I have is a litany of what distortions and limitations the ModWright does not possess. I would say it is to amplifiers what EMM Labs is to CD players -- a truth teller -- faithful to the recording and incapable of editorializing.

So is this the holy grail of amplification? Of course not! There are amps with more explosive firepower, more thunderous bass, high maximum output levels or greater resolution. What the ModWright shares with other great amps is the sense of ease and the natural tonal reproduction of familiar acoustic instruments, the scale necessary to reproduce the 88 keys of the piano, and the ability to respond to every different kind of music. It's not a Class A amp, although it operates in Class A for the first few watts, so it may yield in presence and tone color to some larger chassis and hotter running designs, but it never sounds thin or uninvolving.

It is enormously impressive in smaller scale music, be it the Diana Krall Trio or the Tokyo String Quartet, where it's even handedness over the entire frequency range and its powerful and linear dynamics enables the recording to reach the ears without roll-off or hint of compression. It's the kind of amp that reveals the full depth and width of sound spaces, making it easy to follow complex musical lines as the size of the forces involved increases. It revels for example in giving precise location, size and body to the Monteverdi Choir in John Eliot Gardiner's limited edition box set Bach Sacred Cantatas [Archive 4778735]. Sticking with Bach but switching to the Linn Sondek LP12/Itok /Clearaudio Virtuoso Wood/ Aviva Pulsus front end, the KWA 150 SE digs deep on Peter Hurford's survey of the the Organ Works [Argo D2073D], but reveals major differences between the last two pairs of speakers I've reviewed, the Totem Metal and the YG Carmel. The Metal has the full measure of the lower octaves, effortlessly rolling out the pedal notes, while the Carmel shows greater alacrity and resolution but does not have the full bass impact.

Sticking to vinyl there are few finer sounding LPs than the Ray Charles / Cleo Lane recording of Porgy and Bess [Classic Records / Rhino JP1831]. On "It Ain't Necessarily So" the Carmel delivers a free and easy bass, an open top and the cleanest piano I've heard. The image is huge, the cymbals gentle and the balance ideal. Cleo's voice is silky while Ray Charles almost talks his way through the songs. The combination delivers almost unprecedented realism. While not as open at the top, the Metal has greater swing and energy in the bass. The amp can deliver the whole package, but then it is up to your room and your speakers.

I've spent a lot of time with the ModWright and if I'm not enjoying the recording, it's all down to the recording itself. I've been validating this assertion through some high end headphone setups which bypass the amp. This amp does not sugar coat. In fact it's quite unforgiving. This means the best recordings sound amazing and the worst -- well you won't want to listen. By worst, I'm not necessarily talking oldest. I've been enjoying fifty year old recordings and even some great Louis Armstrong from the twenties. I'm referring instead to recordings that have been compressed to sound great on radio stations. Comparing early CD pressings of the Beatles with the latest EMI remastering is most instructive. What was once harsh and flat is now clear and dynamic. Also unpleasant is a lot of early digital fare. Things have improved a lot now but there are some CDs that sounded less obnoxious when I had a less revealing amp, like the YBA Integré DT, driving the system.

I've been using the Bryston 4BSST² as my reference amp for the last two years, and truth be told, there isn't a great deal of difference between the Bryston and the ModWright with the YG Carmel or with Totem's "The One" or with the Wilson Benesch Act 1. Both amps are exemplary in this company. Yes the KWA shows some extra refinement, has a more articulate bass, resolves extra detail and is sweeter in the treble but the margin of improvement in each area is small, since the Bryston hits such a high level already. Both throw a large stable image and operate effortlessly with demanding material. The Bryston is also a less expensive component at just over half the price. Where the ModWright holds the more significant advantage is in its ability to drive the most difficult loads with ease, the Totem Metal being one example. It is also a better looking amp in my book, but takes up a few more inches in height and depth and weighs significantly more even than the heavyweight Bryston.

The law of diminishing returns sets in fairly early with power amps, sooner than with source components speakers or cables. The Bryston 4BSST² does a remarkable job for under $5000, and I'm sure it's not alone in that. ModWright has three other amps to prove the point. I can't promise the premium the Signature Edition commands over the KWA 150 is better spent here or on a better DAC or preamplifier, but I can tell you this is serious kit, remarkably refined, fully competitive and well able to partner the finest hardware. Just feed it some delicious music and let the fun begin.

Specifications
Type: Solid-state stereo amplifier
Power Rating: 150 Watts @ 8 Ohms (stereo) at .04% THD
   275 Watts @ 4 Ohms (stereo) at .04% THD
   450 Watts @ 8 Ohms (bridged mono) at .04% THD
   650 Watts @ 4 Ohms (bridged mono) at .04% THD

Noise Floor: -100 dB unweighted 
Gain: 26dB
Sensitivity: 1.5 V
Bandwidth: 10 Hz to 100 kHz (+0 dB, -1 dB)
Input Impedance: 20 kOhms
Total Capacitance: 220,000 uF
Inputs: Balance via XLR and unbalanced via RCA
Power Consumption: 1000 VA max
Dimensions: 17 x 17 x 8.75 (WxDxH in inches)
Finish: Black or silver, machined aluminum
Weight: 84 lbs (packaged)
Price: $8495
Warranty: Five year limited warranty

Company Information
ModWright Instruments
21919 NE 399th Street
Amboy, WA 98601

Voice: (360) 247-6688
E-mail: info@modwright.com
Website: www.modwright.com