Saturday, September 19, 2009

Kingrex T-20U

I have had the Kingrex T-20U for a few months now and so a post about this is long overdue.

The Kingrex has been around for sometime and has garnered a reputation for being one of the best sounding of the many low powered Tripath chip powered amps out there.

The designers of Kingrex must have paid careful attention to the many tricks that the DIY community were incorporating in Tripath amps as many of these tweaks and part changes can be found in the Kingrex such as :-

1. Film coupling caps
2. Premium air core inductors
3. Uprated low ESR local power supply caps
4. Heatsinked Tripath chip
5. Socketed op-amp for ease of opamp rolling (for the DAC only)

The icing on top of the cake is the Burr Brown PCM-2702E DAC with USB interface. Looks like this amp is clearly targetted at the PC audio crowd and you can say is perfect for powering small speakers on a computer desktop.

The T-20U is based on the Tripath TA-2020 chip which is capable of about 10-20 watts per channel into 4 Ohms (power varies depending on measured distortion level).

Rather than try to make this a detailed analysis of the circuit design and features of the T-20U, you would be better served to refer to the 6moons review on the T-20U at

I didn't plump out for the matching linear power supply (hi-fi has a mysterious way of emptying the wallet ... so it has to wait for the time being), so any observation on the sound is based on the supplied switching power supply provided.

The Kingrex sounds like most other Tripath based amps. Quite similar in balance to my Trends TA-10.1, the Kingrex has a weighty and slightly full bass. I prefer Tripath bass compared to Icepower bass which is extremely tight and extended, to the point that I find the bass too prominent, attention grabbing and somewhat unnatural.

The midrange and high frequencies are fairly neutral and the slight lack of depth in the midrange and air in the high frequencies differentiate the Kingrex from its much more expensive competitors.

I don't do PC audio, so I did not have a chance to evaluate its USB input and DAC.

Keep the load easy (stick to a speaker between 4-8 Ohms and sensitivity of at least 89 db/w/m or higher) and the Kingrex represents a good value amp with clean and musical output that belies its price tag.

Comparison with my modded Trends TA-10.1 were most interesting. My Trends amp is moderately modified, with the following changes made :-

1. Coupling caps changed from Bennic metalised polypropylene to Auricap
2. Stock volume control changed to Panasonic miniature pot
3. Inductors shielded with copper
4. PCB tracks cut for direct wiring from RCA input to pot and back to coupling caps

The Trends was clearly better in every aspect and was also much cheaper to start off with. Sound was clearer and more coherent with low level resolution superior to the Kingrex.

I don't think this means that the Kingrex is a bad buy. However, it indicates that a stock standard T-amp (check out the many cheap T-amps on ebay nowadays) is capable of performing just as well, or even better than the Kingrex with some judicious modding.

The Kingrex is therefore suitable for the audiophile who does not have the desire or ability to mod the unit, or one who attaches a premium to the professional finished look of the Kingrex.

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