Impression of Consonance KT88 SE Integrated Amp

Date: Fri Nov 30, 2001 4:48 pm

Posted by Tim

Just a few lines on my impression on the Consonance KT88 SE integrated amp - the "Cyber 10". I have never been comfortable about writing proper review but I will give my comments on this little amp which Stanley so kindly lent to me for evaluation.

First of all, some description on the basic features. I always like small tube amp and that is why my first amp is a VTL Tiny Triode (the Manley Reference version) and own so many EL84 amp. The Cyber 10 definitely fits in the category of small tube amp even as it is still probably slightly bigger than the Houston Mini 1998.

I have uploaded a few pictures of the Cyber 10 under our "Photos" section at:

http://photos.groups.yahoo.com/group/hktubeaudio/lst

As you can see, the amp look almost exactly the same the Reference Series from Opera Audio but it is actually much smaller. That's why I believe it is more appropriate for the model name to be "Mini Reference" rather than the cheapo "Cyber 10".

Instead of KT88, the Cyber 10 actually shipped with 2 x Chinese made 6550A tube as output (one for each channel since it is a SE amp) with 1x Japanese NEC 12AU7A as driver and 1x JJ ECC83 as input/pre-amp stage, in a pretty professionally packed box.

The manual mentioned that the amp can use KT88 as well as EL34/6CA7 and KT66. I measure the plate volatge at 360V which means that probably EL37, 6L6GC, 5881 can be used like the Wai Lee power amp (except 6V6 and 6L6G). The Cyber 10 operate the output tube in UL mode to give 12W power, which should be lower than the pentode connected Wai Lee power amp. There is also a switch to operate the amp in triode mode which halves the output to 6W. More about choice of tube and power later.

There is one feature which distincts the Cyber 10 with similar pentode SE amp such as Wai Lee, Audion Sterling, Air Tight M101 and the vintage Pye Mozart. While all of the above use a self-bias circuit, the Cyber 10 incorporate a fixed bias design. This is perhaps a good thing as fixed bias should give more power.However, Opera Audio decide, perhaps due to cost saving, to use a single bias adjustment mechanism for BOTH output tube, similar to what ARC used. This means that, at least in theory, we must use closely matched output tube, which is hard to find for NOS or used vintage models.

The bias adjustment is done by inserting a resistor connected to a phono jack (which came with the amp) and measure by a voltmeter and there is a trim pot for agjustment to get to 0.4mA bias current. This can get a bit tricky and not too difficult once you tried a few times.

Soundwise, I like the amp a lot. It does not sound particularly tubey but all the nice thing with SE tube amp are present. I do not perform any A/B comparison but I believe the amp is more powerful than the Audio Sterling and surely more powerful compare to the Air Tight M101. The sonic character is toward the cooler end of spectrum rather than warm compare to the Wai Lee and Pye Mozart.

As an entry-level tube amp, it is much better than the Houston Mini19XX series and ever better value than the Audio Sterling, particularly if what one after is an integrated amp. I would regard this as the best buy entry level tube amp in the market today (although I did not yet had a chance to audition the similar price new EL84 PP integrated amp from Spark which TKL seem to like so much.

But I know PP amp will most certainly sound different compare to SE amp).

Violin is a particular killer with this amp, especially with the Spendor BC-1, and a must-try in any audition.

Unfortunately, I did not have a chance to try the headphone output but that is no doubt a big bonus.

Now, all of you will expect I must have rolled different tubes in this amp, right? And for sure I did. But the result is very different from what I expect.

The first tube that I tried is the Valve Art "thick glass" KT88 borrowed from Stanley. This tube gives more warmth to the sound but at the expense of reduce punch and treble clarity. I used the stock Chinese 6550A in most of my audition.

I have used different vintage of GEC and Gold Lion KT88 on the Cyber 10 and while they all give better tonality and texture, power is much redcued even with proper bias adjustment. And I have also tried Mullard metal base EL34 and GEC KT66 on the amp and the power loss were even more dramatic.

So my suggestion is to stay with the stock 6550A and only focus on the 12AX7 (most senstive) and 12AU7 for any tube rolling fun.

That's all from me for now and please come to VS or Consonance for an audition yourself.

Highly recommended!


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