Decware Zen Triode Amplifier

[Argus]

I seen many reviews on the Decware Zen Triode Amplifier. Is it really as good as presented, or this hype?

Enquiringly minds want to know.

 

[Count Arthur]

Regardless, you're going to need some very efficient speakers to hear much:

There are headphone amps that put out more power than that.

 

[Jim Matthews]

Zero Global feedback implies higher distortion levels than state of the art.

Matched with wideband driver (no passive crossover components) it might sound pleasant.

The advantage of higher power amplifiers and digital signal processing is your loudspeaker choices are broader, easier to obtain and less expensive.

 

[DVDdoug]

This might be a perfectly fine amplifier, but...

To me, using 1950s technology is silly and it's uneconomical (high cost per-watt). Also, tube amps are less energy efficient than solid state amps and class-A is the worst! (In this case 65W of power consumption for 2.3W out!!!)

The design also features a self-biased output-stage which is 100% stable making bias-runaway and premature tube failures obsolete. There are no tedious adjustments making this amplifier virtually maintenance free.

This is a good design philosophy. Some tube amps are sensitive to tube changes (so people can switch tubes to change the sound). That's an unstable design and the sound will also change as the tube ages or with normal tube-to-tube variations with the same manufacturer and part number.

In addition to this extreme simplicity, there is also no negative-feedback giving you unlimited sound-stage depth.

And this is generally bad design philosophy. Negative feedback (corrective feedback) is the little steering corrections you make to keep your car in the lane. It's also how you (or your cruse control) maintains constant speed and it's how an airplane can fly half way around the world and land on at the right place, on the right runway, at the right airport, in the right city.

Since I seem to be stuck on the navigation analogy, an amplifier without feedback is like dead reckoning... Pointing your boat in the right direction and hoping to land at the right place.

Negative feedback in an amplifier works at "lightening speed" and it tends to lower distortion and noise, as well as flatten frequency response. Plus it makes it super-easy to very-accurately set the gain.

Of course you can build a perfectly-good amplifier without feedback but negative feedback is a wonderful thing!

 

[dfuller]

Single ended triode mode EL84, no feedback... This is absolutely silly even for a tube amp. You will need extremely sensitive horn loaded speakers to get any appreciable volume out of these. Further - "cryo treated beeswax film/foil" - what? Why!?

This is a good design philosophy. Some tube amps are sensitive to tube changes (so people can switch tubes to change the sound). That's an unstable design and the sound will also change as the tube ages or with normal tube-to-tube variations with the same manufacturer and part number.

It just means it's cathode biased, not grid biased. Nothing special here at all.

 

[egellings]

Negative feedback is not instantaneous, but close to it, because there is a delay between when the signal hits the amp's input and when the signal makes it to the amp's output terminals due to limited driving current dealing with reactive components & strays. This delay can cause instability if too much inverse feedback is attempted. Drink too much and you'll fall right over.

 

[LTig]

Negative feedback is not instantaneous, but close to it, because there is a delay between when the signal hits the amp's input and when the signal makes it to the amp's output terminals due to limited driving current dealing with reactive components & strays. This delay can cause instability if too much inverse feedback is attempted. Drink too much and you'll fall right over.

Except of extremely few models where a boutique designer failed to implement the proper amount of negative feedback all other amps are stable into almost all speaker loads on the market - full range electrostatic speakers being possible exceptions.

 

[dfuller]

Negative feedback is not instantaneous, but close to it, because there is a delay between when the signal hits the amp's input and when the signal makes it to the amp's output terminals due to limited driving current dealing with reactive components & strays. This delay can cause instability if too much inverse feedback is attempted. Drink too much and you'll fall right over.

This really only starts to apply at high frequencies, usually above AF.

 

[egellings]

That is true, but there is also low frequency instability called motorboating, a malady of tube amps using output transformers when too much feedback is attempted. I'm not aware of that being an issue with S.S. and OTL designs.

 

[JuliaCoder]

But still, I have a soft spot for Colin Chapman's simplify, then add lightness credo.

 

[levimax]

To me, using 1950s technology is silly

This is not 1950's tube technology which was way more advanced. Single ended triode technology dates back to 1930's and even earlier. This amp does not even use a triode tube (EL84 is a pentode tube which is "strapped" to make it act like a triode). This design looks like maximum hype and good looks using as cheap of tubes as possible.

 

[egellings]

S.E. amps supply basically table radio sound.

 

[Vini darko]

I seen many reviews on the Decware Zen Triode Amplifier. Is it really as good as presented, or this hype?

I think that would be a matter of taste and circumstance. The simplicity of these types of amp is charming. Not something I'd be willing to spend money on though.

 

[MakeMineVinyl]

I looked at this amp to drive my horn supertweeter which I sometimes use with dull sounding recordings, but ultimately passed on it.

This amp might be great for somebody who has extremely efficient speakers (>98db/1 watt), but for those buyers I'd just go with a real SET which uses 300B or 2A3 tubes. SET amplifiers may not be 'clean' with immeasurable distortion, but neither are your speakers.

 

[mhardy6647]

I seen many reviews on the Decware Zen Triode Amplifier. Is it really as good as presented, or this hype?

Enquiringly minds want to know.

I've had one of Deckert's "Zen" amp, the SE-84B morph, since the late 1990s.
It... actually sounds pretty good.
It is very quiet (in terms of hum).
It is very, very very low powered.

DSCN5766 by Mark Hardy, on Flickr

It would make a pretty good tweeter amplifier in a bi/multi-amped system.

It is not sufficiently sensitive to use with real (recorded) music to fill a room, even with loudspeakers of ca. 100 (or greater) dB/watt @ 1 meter sensitivity (e.g., in my case, Klipsch Cornwalls, Altec Valencias, and even my current "Frankenaltecs".

DSC_9988 by Mark Hardy, on Flickr

The little amp used to be quite inexpensive. Decware got subsumed by their own hype* and now they're not at all inexpensive. In fairness, they're hand made in Peoria, IL -- but dollar for dollar, stick with something a tad more practical (e.g., SE 2A3 amplification) and you'll likely be happier, and better off, in the long run.

SE84B zoomin by Mark Hardy, on Flickr
____________
* If you've ever read any of Deckert's "white papers", you'll see why I tired of his hyperbole and the whole Decware "scene" pretty quickly. "Sound signature" is perhaps even more meaningless and irrelevant than PRaT!
I will say, though, that (like monkeys and typewriters -- or perhaps blind pigs and truffles) he/they do seem to stumble on some pretty good sounding recipes now and again.

 

[mhardy6647]

Oh, there was a big kerfuffle in the late 1990s about the power output claims Deckert made for these amplifiers. He initially claimed 5 wpc, but his bluff was called. Long story short, the aforementioned SE-84B version was capable of about 1.2 watts per channel at "hifi" levels of distortion (ca. 5%). In my own hands, the "B" morph gets very strained sounding reproducing "little girl with guitar" music at moderate volume levels in a mid-sized (by American standards) room using the aforementioned Klipsch Cornwalls.


I would not believe the 2.3 watt spec (even at 10% THD), full stop.

https://audioxpress.com/article/a-beginner-6bq5-se-amp says "about two watts", though -- in fairness & in full and complete disclosure.

 

[MakeMineVinyl]

I would not believe the 2.3 watt spec (even at 10% THD), full stop.

My 2A3 amplifier has 57.06 milliwatts more power than your 2A3, and probably has better SINAD too (if I could only get my analyzer to settle down to get a stable measurement).

 

[anmpr1]

Not sure how good this is. It sells direct for a thousand dollars. 2 watts. The Randall RD1H has one watt, for six hundred dollars. But with the latter you also get some preamplification and tone settings, so 1+ for Randall. Strictly on a watt to watt basis, it's sort of comparable. I found the following 'subjective' description of the Randall, on line somewhere. I would tend to think his description is accurate. I'm not sure how the Decware would sound hooked to a 2x12. Probably a little more power in the clean, with softer grunge when overdriven. /s

Let me be clear and brief: This amp astonished me, after my ENGL Savage tube amp head, I had never been in such awe. This amp made for home (1 watt), has a killer sound. I plugged it to a 2x12, and it sounds wicked, with a somewhat dirty Crunch, just the way I like it, and with a metal distortion that's jaw-dropping.

 

[steve f]

I owned a Decware SE84B purchased directly from Decware. A few things I found out rather quickly. I doubt it produced 2WPC At less than 1% THD. At the time 2 different output transformers were available. I opted for the 8 Ohm version. (Modern versions now have a high low selector.) It NEEDED to have a preamp in front of it to sound decent. Also, a lot of high efficiency speakers have too complex of crossovers for the low output, and tiny output transformers. I got best my best results with either a single driver back loaded horn, or a 94DB efficient two way using an 8” woofer and the simplest first order crossover. This was the amp that got me to quit experimenting with SETs. Seriously, it’s just a bad choice for most speakers, and way too easy to overdrive. For very very efficient speakers only.

 

[mhardy6647]

I doubt it produced 2WPC At less than 1% THD...

I believe it's about 1.2 watts (per channel) at 5 or 10% THD (10% was the prevailing "hifi" spec when amplifiers like the Zen -- but using EL84s in their native mode as pentodes -- were widespread). It is a very low powered amplifier, even by my standards, which is why mine's packed up in its little box.

Only 1 OPT when my SE84B was new, FWIW (serial number 190, if memory serves...I could check). The secondary was 6 ohm, which Deckert touted as "optimal" (I am sure he used fancier words, and more of them) for either 4 or 8 ohm nominal loads. I can tell you it sounded pretty awful driving a pair of 15 ohm Lowthers.

PS You, perhaps, should've tried SE 2A3 before you gave up on SET amplifiers.