A few months ago, I decided to look around for a solid state amp to compare to my 45 watt EL-34 based tube amp. After enjoying the tube amp for a year, I was wondering if another amp would drive my speakers better on loud music and more intense rock and classical pieces. I really enjoy the "presence" that tubes give on jazz and female vocalists but when listening to rock, it sounded a little anemic. After looking around a little, I ran across the Odyssey amps and gave Klaus a call. After describing my system to him, he suggested the Khartago monos for their current delivery capability. In Klaus's words, the Khartago Monos would be better (if only slightly) than the Stratos and Stratos extreme for my system. He thought that to get a significant improvement, I would have to at least go to the DM or likely the Mono Extreme, which thanks to his amazing trade up policy, I will likely do in the next few years.
The specs that came with the Khartago Monos literature are listed below. I have not seen them anywhere on the web yet so I though it a good idea to provide them for reference.
150 watts into 8 Ohms class A/AB
300+ VA single toroidal transformer per channel
120,000 uF capacitance
>100 amps current RMS (as a comparison, the Khartago Stereo lists >30
>amps of current delivery).
Damping Factor >800 continuous @ 8 ohms
Now the Stratos line is also 150 watts per channel with capacitance of 60,000 uF (Std), 120,000 uF (Plus), 180,000 uF (Extreme) with current delivery of 45 amps and a damping factor of >500 continuous. Just looking at the specs, the Khartago monos compare very well to the Stratos. While the total capacitance is below the Stratos extreme, it has greater currently delivery capabilities. Specs aside, the real truth is in the listening and my guess is that a pair of Khartago Monos and a Stratos Extreme would sound a lot alike. Obviously, the Stratos are better looking.
My speakers are Green Mountain Audio Europas which are 6" two-way, ported, 4 Ohms load with a flat impedance curve and 88-89dB/2.83Volts @ 1 meter. They have a relatively unique 1st order cross over and love to be played loud. I have hear reviews where they were played in excess of 105 dB before distorting. The cabinets are made of a very heavy, inert marble-like material and weigh 43 lbs each. I am currently using a Bottlehead Foreplay preamp that I have heavily modified. My source is a Sony 555ES SACD player that I use with a Perpetual Technologies P-1a/P-3a DAC for Redbook. My room is rather small and about average as far as sound quality goes. I actually am in the process of building a new family room (15'x24') off the back of our house with 10'-14' ceilings, which I hope will provide a nice large home for my stereo set up. This is another reason why I figured it would be good to investigate better amplification
.
What I heard:
Bass was definitely tighter with the Khartagos compared to my tube amp. I would also say that it is more nuanced. What I mean is that not only was their more low frequency sound but I could differentiate different aspects to it. For example, with a stand up bass on some blue grass recordings, I could make out different low frequency notes whereas before, it just sounded like he was hitting the bass. I heard similar things with kick drum and other low drum sounds.
Quickness - The Khartagos definitely respond faster. This is especially true during dynamic sections of music or when the main singer suddenly raises the volume of his or her voice. In my mind's ear, this translated as a more intimate experience.
Warmth - this was an area where I was concerned when going from tubes to solid state. I originally went to tubes to escape the overly bright highs that made me cringe. I am happy to say that the Khartagos are not "analytically bright" in my system. I hear that this is also true with the Stratos which makes sense since they share some of the same boards. Female voices sounded intimate which is something tubes do very well and I enjoyed. I will say that my tube amp did have a more mellow and sweeter overall presentation which many would call warm but the trade off was dynamics in my system. I bet that the right tube amps with high efficiency horns would have both the dynamics and warmth if that is what you are looking for. I was pleasantly surprised that the Khartago monos are very quick (dynamic) and suitably warm in my system. My guess is that a system that tends towards bright due to cables, speakers or source, would probably still sound bright with these amps as they seem just a little to the warm side of neutral.
Sound stage - here is the other area were I figured the tubes would dominate and to a degree, the tubes did. I thought the overall width of the soundstage with the Khartagos in the chain was a little narrower (not by much) but at the same time was rock solid. The tubes had more of that magic rounded sound to different instruments from left to right which is very appealing but I think I like the more detailed and specific location for each instrument a little better. I think this is due to the quicker dynamics and greater detail.
Detail - speaking of detail. On complicated pieces, it was no contest. The Khartagos were much better at delivering more focused sound at higher levels. With softer jazz pieces with just a sax, piano and or brushes, the Khartagos sounded just as good as the tubes which is where the tubes excelled. I was very impressed with some drum solos where I very easily knew where the symbols were coming from when compared to the other parts of the drum set and other instruments in the music. I know a lot of this is due to the way the music was mixed, but with the tube amp, it was not as well focused.
Overall - well as you can tell, I liked the Khartagos Monos compared to the tube amp. Since I want to be able to listen to rock and dynamic classical as well as female vocals and jazz, I will be selling my tubes. I really like the way the tubes sound with relatively mellow music but, at this point, I will trade a little of the lush magic of tubes for more dynamics of solid state without giving up much (if any) of the warmth and intimacy. I was expecting to loose the "singer in you room effect" when removing the tube amp from my system but it really didn't happen.
P.S. - For anyone in the Washington DC Metro area who has a Stratos stereo or mono amp, I would love to compare the Khartagos.
