ModWright Instruments KWA 100 Ampli er and LS 100 Tube Preampli er
Earlier this year, in the April/May 2012 issue of CANADA HiFi, Phil Gold reviewed the ModWright Instruments KWA 150 Signature Edition Ampli er. He was so impressed by this ampli er that it ended up nding a permanent spot in his audio system. His high praise of the ampli er also inspired us to bring in a couple of the more affordable pieces from ModWright, the KWA 100SE Ampli er and LS 100 Tube Preampli er. If you’re not familiar with the ModWright Instruments brand I invite you to read Phil’s review as it does a great job of introducing the company. All ModWright Instruments components are designed and hand-made in the USA.
So how did these two entry-level ModWright components fair? Let’s start at the very beginning. Both components were double-boxed for shipping. But I was surprised that the inner box of the LS 100 preamp was signi cantly larger than the preamp itself. Inside, the styrofoam inserts were smaller than the box and hence could not fully prevent the LS 100 from moving inside the box during shipping. The ve tubes included in the box were scattered loosely inside the box, three of them had fallen completely out of their paper boxes. Luckily none of the tubes were broken. I contacted the manufacturer to make them aware of these issues and was told that as long as the tubes worked when I rst power on the LS 100, then I shouldn’t have any problems. There were no issues with the packaging of the KWA 100SE amp on the other hand. Let’s look at each component in detail.
The LS 100 preamp has a single-ended tube design and strives to improve many of the qualities offered by the 9.0SE model, designed some seven years earlier. The brushed aluminium enclosure gives it an attractive industrial appearance, if you’re into this sort of thing. The front panel fea- tures two large dials (balance, volume), a series of sunken-in buttons for power and input selection (with corresponding LEDs above each) and 1/4 inch headphone jack. It is topped off by a large, blue backlit ModWright logo that’s anked by large ModWright Instruments lettering on the top and the LS 100 designation on the bottom. Its design features include a single gain/buffer stage, phase inverting and an upgrade slot for an optional in-board DAC or phono stage. The base LS 100 preamp retails for $3,700, or $4,500 with the built-in phono stage or DAC. My review unit was equipped with the phono stage. The LS 100 offers a bank of ve inputs (4 RCA, 1 XLR), three outputs (2 RCA, 1 XLR), one monitor input and tape out, as well as a home theatre bypass input. Two remote trigger outputs and an IEC socket, for a removable power cord, round out the rear panel. The supplied remote has a compact form factor, similar to remotes supplied with mini stereo systems, but offers nearly all the same functionality as the front panel buttons. Frankly, the remote looks and feels a bit cheap.
Like some of the other tube-based components on the market, the LS 100 preamp requires some assembly – namely placing the tubes inside the sockets. It’s a fun, engaging process that gave me the opportunity to get to know the component a little better. To get the tubes into place, the top cover of the LS 100 needs to be completely removed, which means undoing 20 hex screws with the provided longhandled hex key. The LS 100 uses three tubes: two 6SN7 driver tubes and a single 5AR4/GZ34 recti er tube. The optional phono stage board requires two additional tubes – a 12AU7 and a 12AX7. If you get
the LS 100 model with the phono stage, you’ll want to con gure the phono stage to have the correct loading impedance (to match your turntable) while the cover is off. This is accomplished by setting up two banks of boardmounted dip switches which provide loading impedances of 50, 100, 500, 1000 or 47 kOhm, with the option of 100 pf of capacitance. My Clearaudio Concept turntable has a loading impedance of 47 kOhms so I set the dip switches accordingly. Fitting the tubes into the sockets is very simple but setting the loading impedances may leave novice users scratching their heads since it’s not explained in the manual as well as it could be (a diagram would be nice).
The KWA 100SE amp ($4,500) has the same brushed aluminium enclosure, with rounded edges and corners. Its front panel is completely free of buttons, with only the blue backlit ModWright logo sandwiched by the ModWright Instruments lettering on the top and KWA 100SE on the bottom. The power switch is tucked away, out of view, on the left side, on the underside of the chassis. The SE designation at the end of the model number stands for Signature Edition and demands $800 more, over the base model. The KWA 100SE features a solid stage design but promises to combine the advantages of both tube and solid state designs. The SE edition of this amp offers a little more power and less distortion than the base model. Its power is rated at 120 watts per channel (at 8 ohms, 0.07 % THD) or 210 watts per channel (at 4 ohms, 0.07 % THD). The SE edition offers higher grade resistors and ModWright’s proprietary capacitors (also found in the preamp), as well as ve pairs of Mosfet output devices per channel, compared to the three pairs in the base model. Total capacitance is rated at 180,000 uf, compared to 90,000 uf of the base model. At the core of the KWA 100SE lies a single voltage gain stage called the “Solid State Music Stage”, a circuit designed by Alan Kimmel, creator of the vacuum tube “Mu” stage. Highlights of this amp’s design include a high-low bias switch and true balanced oating inputs. Its rear panel accepts both XLR balanced and RCA unbalanced inputs. A master power switch, silver multi-way speaker binding posts and a power IEC port round out the rear panel.
Powering on this ModWright Instruments pair has to be done in the right order – the preamp rst and then the amp. Otherwise, the protection circuitry in the amp might be tripped up and in the worst case, you might damage your speakers. The preamp takes about 20 seconds to start up, while the amp takes closer to 55 seconds. I had the ModWright Instruments pair hooked up to my trusty Focal Electra 1008 Be II speakers and used the Bryston BDP-1 Digital Player / BDA-1 DAC and the Clearaudio Concept turntable as my sources.
During the rst two months this duo spent at my house, I listened to plenty of different types of music and gave the components ample time to burn-in. Unfortunately when I was about to sit down and begin my critical listening for this review, an issue surfaced with the LS 100 preamp. Suddenly it began
introducing a noticeable noise into the signal chain and also became ultra sensitive to any kinds of vibrations – the smallest tap on the case got ampli ed right to the speakers (even walking in front of my system caused this to happen). It turned out that one or more of the tubes had become microphonic, something that can happen with tubes. However ModWright quickly recti ed the problem by sending me a new set. After going through the burn-in process again, I was nally ready to give this pair a proper listen.
I have to admit that I was pretty excited about the combination of a tube preamp and a solid state amp working together to produce sound – I gured that if they worked well together I could potentially have the best of both worlds. It’s become somewhat of a tradition now, that every time I test a new component I go on a new album shopping spree. Among the new artists, now loaded on my SSD drive and played by the Bryston digital player, were Sonoio, Alabama Shakes, City and Colour, The Lumineers and Alex Clare. As part of my tests I of course included numerous albums that I’ve listened to before on many other components.
I began my listening session with Rebecca Pidgeon’s “Spanish Harlem” from the Best Audiophile Voices Collection. I was immediately captivated by the realness of the sound produced by this duo. Rebecca’s voice was silky smooth and echoed gently in the originally recorded environment. The strings of the double bass were well articulated and produced rich bass notes. Similarly piano keys and the violin played with rich overtones. Everything about this presentation had a lifelike quality, as if I was listening to a live show. The highs had just the right amount of sparkle, while the bass line played tunefully and never lacked in depth. The midrange offered great clarity and rhythm.
Tracks from AIR’s Moon Safari disc presented an expansive soundstage that I’ve come to appreciate from this album when played through capable audio equipment. The ModWright duo resolved the numerous, often complex sonic layers of this music with ease, while delivering all of the ne details of each and every layer. The dynamics of the presentation never disappointed.
Next I jumped to the Jagged Little Pill Acoustic disc from Alanis Morissette. All of the tracks on this album offered rich, full-bodied acoustic guitar notes, with remarkable harmonics that one would expect from a real guitar. Different guitars offered clearly distinct sound characteristics. I could also easily determine the strumming pattern of each guitar on most tracks. Alanis’ quirky voice was reproduced with all the veracity of a live performance. The ModWright components presented me with a properly laid out, three dimensional soundstage where the vocals and every instrument had a precise position and a good amount of air around it. Tracks from City and Colour’s “Little Hell” once again recon rmed all of my conclusions about the imaging and soundstaging.
Having a tube design, the LS 100 does not offer as low of a noise oor as a non-tube preamp design. If you’re close enough to the speakers you will hear a little bit of a constant noise. This however is completely expected and in my opinion does not take anything away from the listening experience.
As mentioned earlier, the LS 100 preamp provided for this review included the optional on-board phono stage and this is what I turned my attention to next. The LS 100 offers a gain of 70dB and is capable of handling both MC and MM turntable cartridges even though it doesn’t have the typical switch for this selection. That’s because it offers plenty of headroom for both cartridge designs. Once again I listened to a large variety of recordings, ranging from rock to classical. Regardless of the musical selection, I was consistently presented with amazing resolution and precise imaging within a vast soundstage. The LS 100 allowed my Clearaudio Concept turntable to deliver delicacy and smoothness from classical recordings and great dynamics from hard rock recordings like I’ve never experienced before from my turntable. Thanks to its tube design, this phono stage added yet another level of realism and uidity to each song that I listened to.
During its stay on my audio rack, the ModWright Instruments KWA 100SE amp and LS 100 tube preamp provided me with many hours of enjoyment. What started as tapping my hands on my knees often ended in air guitar or air conducting. There is no question that there is a great synergy between these components – what I was listening to was truly a fantastic combination of both tube and solid state designs. Despite the issue that I experienced with the LS 100 preamp at the start, my overall experience with the ModWright duo was very positive thanks to the excellent sonic presentation achieved by them. I communicated the packaging issue to both the manufacturer and the Canadian distributor and I’m certain that both will address this accordingly for future shipments. The LS 100 is a exible pre-amp that offers plenty of inputs, both balanced and unbalanced, and thanks to its tube stage is capable of breathing the textures and realism that exist in real voices and instruments. The KWA 100SE is an amp that offers the control and dynamics that one would expect from a high quality amp, while offering a great depth of details. Together there is a sense of musical magic between these two components, that’s for sure. Bravo ModWright Instruments!