- Written by Jared Rachwalski
- Published on 20 November 2008
The Jaton company has been around for over 25 years. They started with manufacturing PC video cards, and have since branched into home theater and hi-fi gear. Jaton's Lyra HD-661 DX speakers were recently reviewed at Secrets, and their interesting design and great sound made me want to try out their amplification. George Cheng from Jaton was kind enough to send me a rather large and heavy Class A/B Stereo amplifier capable of putting out 300 watts RMS per channel into 4 ohms. Initial problems with the amplifier has required Jaton to redesign it, and the revised version will be sent to me for review. In the meantime, here are some initial observations on the unrevised unit.
- Design: Class A/B Stereo Power Amplifier
- Power: 150 Watts RMS x 2 into 8 Ohms, 300 Watts RMS x 2 into 4 Ohms
- MFR: 16 Hz - 40 kHz, ± 3 dB
- THD+N: < 0.01% @ 8 Ohm, 1 kHz, 150 Watts
- Inputs: Unbalanced RCA
- Dimensions: 7.5" H x 17" W x 14.5" D
- Weight 80 Pounds
- MSRP $6,000 USA
Due to the inherently low efficiency of the Class A topology, in order to get 300 watts output (2 x 150 watts stereo at 8 ohms), you need to consume at least twice that, and the extra power is dissipated as heat. Big heat sinks are needed to expel this energy, and these take up lots of real estate. Jaton claims that the Operetta 2300a stays in Class A operation through about 90% of its operating range. While this is impressive, and may allow the amplifier to run in Class A for most of its operation, it is not a "pure" Class A amplifier, rather a Class A/B. Not that this is a problem mind you, unless of course you think you really need 300 watts of Class A power. While there is a theoretical sound quality problem when switching from Class A to Class B (crossover distortion) in practice this is not audible (depending on who you ask). What you do get is an increase in efficiency which allows you to reduce the overall size.
I wired the Operetta into the Front Left / Right outputs of a Rotel RSP-1069 surround processor, and then on to my Raw Acoustics OB2x Open baffle speakers. Source components included my HTPC playing lossless FLAC files via HDMI, an Oppo 981-HD for SACD, and an Onix XCD88 for CD and HDCD playback. The amplifier was given plenty of break-in time before I did any serious listening tests. For comparison, I used a Rotel RMB-1085 Class D amplifier rated at 100 watts x 5.
In these initial tests, I was very pleased with the sound. There was no lack of headroom, so the amp never broke up at high volumes. Music was very clean and slightly more dynamic in the high frequencies compared to the Rotel Class D.
Fan noise was objectionably high, but this was the only complaint I had.
The Operetta 2300a is a powerful, clean sounding amp, when the fan is not running, that is. Interesting design and use of Class A through most of the operating range provide a very nice warm sound that should work well with most speakers and electronics. I am curious as to what the new version will sound like, and will be keeping an eye on their future products. If the initial listening tests are any indication, this could be a serious contender.