Believe it or not, there was a time when the prevailing wisdom was that all power amps sounded the same. The only difference in the power ratings of the individual amps. I know this might seem incredible to many of you but, if you’re over forty-five or so, you’re not hearing this for the first time. This was the way it was in the days BAS, (Before Absolute Sound).
Fast forward to today; we all know much better than that. It only stands to reason that all amplifiers cannot sound the same given the various types from Class A to tubes.
Back in January, 2016 I reviewed and was favourably impressed by the GamuT D150 Limited Edition Integrated Amplifier [reviewed here]. I was not only impressed by the build quality, but by the outstanding sonic performance. I commented on the unique power supply that was principally responsible for its overall sonic performance.
The output of the GamuT D-200i is 50 watts more than the D-150 LE integrated but there is a great deal more to the story than that. They both utilize the one large MOSFET per channel, but this is where the similarity ends.
The D-200i is a traditional looking power amp that shares the understated elegance that is standard with GamuT products. Measuring 17" x 6.5" x 18.5" and weighing in at 68 pounds, suffice it to say that this is one hefty box. Outputting 220 WPC into 8ohms, and 700 WPC into 2 ohms, it should safely drive the most difficult speaker loads.
The D-200i should rightly be called a dual mono power amp. It uses the unique output stage that is common to all GamuT amplifiers. To briefly recap, the power supply uses only one MOSFET per rail. Both are identical industrial grade NPN mosfets, one for the positive and one for the negative rail. Each are capable of an output of 100 amps, 300 amps peak. This design means that a complementary PNP is not necessary, thereby effectively removing the shortcomings of the traditional multi-transistor output stage. The result is an output section without crossover distortion, no emitter resistors and a very low distortion, consisting mainly of even order harmonics.
The GamuT Single MOSFET design does not need to use a Class A bias. It is a Class AB design, biased to 14-watt Class A. This is in order to run the transistors at an optimum temperature that results in the best sound. GamuT also includes NPN bipolar transistors capable of putting out 25 watts of power which is needed to drive the huge 100 A MosFet NPN output transistors.
The two transformers of the D-200i are 60%, (this partly accounts for the amps 68 lb. heft) larger, 800VA as opposed to the 500VA for the D-150LE. Not only is the power supply much larger, it also exhibits a lower noise floor and is heavily shielded between channels. The result of this design was a 30db increase in channel separation in the high frequency area above 500Hz. In addition, the rectification circuit is balanced as opposed to single ended.
Another features include a non-magnetic chassis and common to every GamuT amplifier, an error-checking start-up sequence that goes through several condition checks lasting a few seconds before allowing full operation. A complex protection circuit can detect DC errors, high-level subsonic signals, long-term ultrasonic signals, high temperatures and low impedance loads. GamuT’s innovation and obsessive attention to detail and innovative design prowess is clearly evident with this amplifier.
Being well over 45, I enlisted the help of my friend and next door neighbor to help me lift the D-200i out of the shipping carton and then onto the bottom shelf of my audio rack. Since my friend is among the uninitiated, I had to explain why this amp was so heavy over a beer.
Making the connections are pretty straight forward. The IEC power socket is located along the top of back panel, dead center and well away from the speaker terminals. The balanced and unbalanced inputs are located at the bottom left and right corners of the amp. You’ll notice that there are two sets of speaker terminals on either side of the case. One set are marked “Direct” and the other is marked “Normal". Both will accept spades, bare wire or banana plugs.
The normal terminals are connected to a Zobel Network. This is a coil in series with a resistor that protects the amplifier from capacitive speaker loads but it tends to create a slight roll off in the treble. The direct terminals do not have this network and therefore leave the treble unaffected.
Symphonic music is a very good test of a system’s ability to produce the full musical spectrum. Listening to Strauss’ Also sprach Zarathustra (RCA Living Stereo 09026-61494-2), Fritz Reiner with the Chicago Symphony, with the D-200i, the full weight of the tone poem is unconstrained, forceful and dynamic. Every section was clearly defined yet it was presented as a musical whole.
Smoke is a premier jazz/supper club here in New York City. When the club was renovated it was done so with acoustics in mind. As a result, it is a favorite of musicians and a number of excellent live recordings have been made there. One of these recordings is Cyrus Chestnut’s Midnight Melodies (Smoke Sessions SSR-1408). This is an excellent live recording of his small ensemble. It is difficult to make a good recording of a piano. The D-200i does an excellent job of reproducing the clarity and recreating leading edge of the notes as well as their percussive weight. The timbre of the instruments ring true throughout the recording. Bass notes are full and resonate with a good deal of textural detail. Listening to this CD was a revelatory pleasure with the D-200i.
Roy Haynes is a master drummer who leads an all-star group on his 2011 CD, Roy-Alty, (Dryfus Jazz DRY-CD-36977). As the leader, Haynes’ drums are quite prominent, almost a lead instrument. The full boom and pop of the drums came through with ease. Roy Hargrove’s trumpet has the right amount of brassiness and bite. David Kong’s bass was ripe, full and due to the D-200i's grip on the bass, it was never bloated.
As I mentioned previously, there are different classes of amplifiers by design but I’m referring here to the different classes in terms of performance. The GamuT D-200i is a high-performance piece of kit that belongs in the upper echelon of high-end gear [and so good, I purchased the review unit]. It’s fair to say that the D-200i shares the GamuT house sound which is characterized by an open, airy sound with very good detail. It’s well balanced from the treble to the bass. It has an uncanny tube-like ability to present an almost holographic sound stage without edge or glare.
An added bonus is the firm grip on your woofers. This allows the user to take full advantage of the extended bass that the amp is capable of producing. Various types of music consistently flow through the speakers with ease. If you are looking for a stellar performer in this price range with the sonic qualities that I have listed above, do yourself a big favour and give the D-200i a listen.
Power Output: 220 wpc into 8 ohms; 400 wpc into 4 ohms; 700 wpc into 2 ohms
Input Impedances: 20 kohms unbalanced; 40 kohms balanced
Input Sensitivity/Gain: Adjustable: 0db/-6 db/12 db/-14 db
Frequency Response: 5-100 kHz +/- 0.1 db
Total Harmonic Distortion: @ 1 kHz ,0.05%
Signal to Noise Ratio: 100 db A weighted
Warranty: 5 years’ parts and Labor
Further information: GamuT Audio
Analogue – VPI Classic 1 Turntable W/Transfiguration Axia Cartridge
Pre-Amplifier – VAC Standard LE w/ phono stage (Rebuilt and upgraded by VAC)
Power Amplifiers – Gilmore Raptor Mono Blocks
Digital - PS Audio Perfect Wave Transport & Perfect Wave DAC
Cables – Audience AU24SX Interconnects and Speaker Wire
PS Audio P-10 Power Plant
Echo Busters panels