Reviewed by: Gary,  an Audio Enthusiast from audioreview.com   

Summary:
The Little Amp that can - a review of the DECware Zen Triode amplifier

Jan.  2000

I got into this hobby about two years ago, when I decided to purchase these awesome Snell C/V speakers. These speakers opened a whole new acoustic dimension to me. Since then I have slowly improved each part in my system, making small, but noticeable improvements in each an every one of them.

Recently I bought this little Zen Single Ended Tube amplifier - except for the above mentioned speakers it is the most significant improvement I have made to my system, and it has seriously changed my view of the way that I will approach (high-end ?) audio from now on. Here is the story:

Expectation
I wanted to outfit our study with a stereo system, and I thought I could do that by using a small tube amp, the one called ZEN that Steve Deckert at DECWARE builds, should come in handy. I had ordered it in mid November and it was supposed to be ready before the holidays, but that did not happen, and it was not so important, since I was fairly busy around that time of the year. It arrived in mid January, in a small box that the UPS guy had dropped off in front of our house, while I was still at work. Well, before installing it in the study I thought that I give it a test run in my stereo/HT room. I opened the box and in the midst of a lot of plastic chips and bubble wrap there it was my Zen Single Ended Tube amp, Number 111, hereafter referred to simply as No. 111.

Disappointment
I unhooked my trusty McCormack DNA 0.5 and swapped in No. 111 in it’s stead, inserted the tubes and fired it up. Well everything came alive ok, but before I could even turn on my Sonic Frontiers pre-amp, one of the output tubes became first very bright, and then very dark, while No. 111 emitted a sizzling noise into one of my Snell C/V speakers. When the pre-amp and the CD player came on, I had signal only on one channel - dang no test run that night. I sent off an e-mail to Steve, describing the problem, and he responded promptly the next day, that on Monday he would overnight a replacement tube. No questions asked, extra charge (cool - I thought he really stnds behind his product)

Redemption
As promised, the spare arrived on Tuesday, I inserted it, and the adventure began. Just on that previous Saturday I had bought a copy of Jimmy Scott’s latest CD, called "Holding back the years". It has been recorded very closely to the mike and generally is a very good recording that images wonderfully. Right from the start I felt that with No. 111 Jimmy was much closer. The midrange was so well extended I could clearly hear every time when Sammy took a breath or closed and opened his mouth. The information was undoubtedly there before, but No. 111 presented it in a different, much closer context. In went the next CD Jewel’s "Hands". This is another good recording, and an HDCD enhanced CD and it sounded great on my system before, but now again it was much closer. The same applied to Anne Sophie Mutter and Yo-yo Ma.

Sonic Frustration
So far I was driving the amp with my Sonic Frontiers Line 1 pre-amp. That way I was able to preset the Zen’s attenuator to about 80%, and open the volume control of my CAL CL-15 all the way, thus reducing any loss of information from the CAL’s digital volume control. This set-up also allowed me to adjust the volume in very fine increments (the Line 1 has 190 0.5dB steps). I always considered this pre-amp as one of the real keeper components, since it is very well engineered, and it does a great job in adding just a little tube glow to the SS amp I was using.

Just for kicks I decided to run the CAL directly into the Zen: holy cow - what a difference again. Now the artists were really all here. It was like just another very fine but important piece of information had been added. What was it though ? I switched forth and back a couple of times, desperately trying to hold on to the SF, but it was not possible. With the SF small nuances in voices and instruments, and in particular reverberation information was not as present as with the direct connection. I could not believe it. No. 111 had just "obsoleted" a $2500 pre-amp and a $1800 power-amp.

After listening again to the above albums, as well as to Eric Clapton and Neil Young’s "Unplugged" album I was completely taken. This amp would not go into the study, it would stay in my listening room.

Underestimations
My listening room is not very big (about 18x12.5x6.5), and it is currently filled with several items that do not really belong there (, but that ended up there because it is in the basement), resulting in a less than optimal acoustic environment.

My Snell speakers are rated at 90db@1W@1m, and I had not expected to get clean sound at higher volume levels from this "about 5W" (i.e. 6 or 7 dB) amp. Well guess what - I was wrong. While there is a point where the sound breaks of (right around 96dB I guess), it is so far away from my typical listening levels, which are not low either, that I should always have enough headroom.

And then there is the contentious issue of the bass. "Well ok tube amps and in particular these small ones will probably not produce good bass," I had expected. Wrong again - and don’t we love to be wrong when it’s to our advantage ? While on account of speakers and amp there was really no low bass audible, anything above 40Hz was just fine, and what may have been missing in the low bass was more than made up by the way the upper bass range is reproduced. In particular guitar, violin, and cello just sound awesomely alive and really like a wood instruments with strings, not like strings of metal attached to wood. I swear that Yo-yo Ma was hiding behind one of my speakers, and Eric Clapton was there also on another occasion.

Limitations
"Are you going to tell me that this $500 amp is better than anything else ?" Well not quite, there are a couple of things where other amps have the upper hand. The real discriminator, that will determine whether you can live with this amp may be how important these things are for you, which ultimately depends on what kind of music you prefer. This amp is accurate but to the extent of being a bit slow, and it seems to lose it just a bit, when the full frequency spectrum is being used, like in the case of big orchestras or life rock music performances. In all cases these limitations set on very slowly, and are not really upsetting. In fact some of them I might not have noticed at all, if I had not listened to some of the music titles dozens of times before.

For my taste of music (small ensembles, individual voices, Jazz) this amp sounds better in over 90% of the time. Definitely enough of a reason to keep it.

Also, regarding the above limitations, I am aware that though decent, the Snell Speakers are by far not as sensitive as some other alternatives that are available, and thus the issues I am raising here may well be addressed and overcome by using a 94 or 96 dB speaker.

Conclusions
If one digs into Steve Deckert’s Website (www.DECWARE.com) , one will find some papers that describe his approach when designing this amp. These papers are full of interesting ideas, and I found his thoughts about "the first watt" most compelling. Basically he thinks that with the introduction of SS circuitry, and in particular integrated chips, we have obtained enormous possibilities for power control, which allowed to design much stronger amps than previously possible. What got lost in this process though is the way that "the first watt" is being designed. This is where he sees his focus, since the "first watt" is really what everything else is based on.

Well I am a believer now, and I will probably get a second Zen (to monoblock and buy myself another 3dB), and in the longrun I may look into more sensitive speakers.

4.99 stars for sound and at least 20 stars for value. At 5 stars this amp is absolutely underrated.