I’ve had the SEWE300B amplifier in use for about 400 hours now. I could write on and on about it but the truth of the matter is that there is a short and sweet answer to “how is it?” It’s a clear and dynamic amplifier that presents an accurate and vivid sound field in audio playback.

The only other 300B amplifiers I have heard were two Cary amps in the late ‘eighties and early ‘nineties. One was an amplifier, the other an integrated amplifier. Neither were heard in my own system. I was very impressed with the sound, the SET nature capturing me first, and then I think the sound of the 300B tubes themselves. The basic sounds of these amps were warm and forgiving and inviting. Hearing these sent me on a search for an SET amp that I could afford. I had grown up on my father’s Dynaco tube system, and had been listening for a few years to a 1959 EICO EL84 integrated stereo amplifier I had bought from a friend (who had been using it as a guitar amplifier and was unhappy with the sound). Eventually I found Decware, talked to Steve on the phone and bought Zen amp #27. It didn’t sound like the Cary amps, but that
Type to enter text was great as they sounded uniquely clear and dynamic and I spent over two decades with Decware amps and speakers revealing in the many different soundscapes and tonal universes they can deliver.

I never forgot that 300B sound though. . . and always wondered what a Decware 300B amp might sound like. And now I know. The SEWE300B sounds marvelous.

For the last five years I’ve used a pair of Decware SE84UFO3 Monoblock amplifiers with all the 25th Anniversary mods. These amplifiers trained me how to get the best out of them and became my time machine and escape platform, giving me thousands of hours of musical enjoyment. I never thought I would replace them. . . until Steve announced the development of the SEWE300B. I knew I would have to hear one, and trusting Steve’s vision and innovation, I knew it would be a spectacular amp and if I heard one I would have to have one. I managed to order one and my intuition about this amplifier was right on. It’s the best amplifier I have ever owned.

My direct comparison to the SE84UFO3 Monoblocks with the 25th Anniversary Mods initially surprised me as the amplifiers sounded so similar. There was a shared clarity and a shared dynamic feel, from micro to macro dynamic playback. And as I grew more familiar with the SEWE300B and as the amplifier broke-in and seasoned, its distinct character became more recognizable. There was a feeling of easy “power” delivered to the Decware HR-1 speakers I have used for over 12 years. The SE84UFO3 Monoblocks with the 25th Anniversary Mods worked surprisingly well with the HR-1 speakers, but the speakers were better matched with the additional “power” from the SEWE300B. There was a teaspoon more heft to the sound of the lower frequencies, and a similar bit more detailed portrayal of the sound of a contrabass violin, cello, or electric bass guitar, and a bit of sparkle to the higher frequencies, a tiny bit more transparency to the recorded sound of trumpets for example—their sound burst out from the collage of accompaniment a bit more than the quite satisfying way the SE84UFO3 Monoblocks with the 25th Anniversary mods portrayed them. And I enjoyed the same voltage regulation benefit shared with the Monoblocks which allowed me to tailor the overall amplifier sound by using different combinations of voltage regulation tubes. The overall sound can be slightly lush to very quick and clean and many different points in between those two end points using the three different voltage regulation tube types and different brands of each. I would think any owner could find the right combination for their taste and system needs. Like the SE84UFO3 Monoblocks with the 25th Anniversary Mods the SEWE300B also has two bias signatures switchable for the input tube, and two settings for the speaker connections, and these also offer flexibility to the overall sound. An owner of the SE300B can explore many sonic possibilities with these switches. These switches and the voltage tube regulation set this amplifier apart and aid the owner to find the right set up for his system.

As is my nature as a tube fancier, I rolled a number of tubes in all positions except for the 300B tubes themselves, as I only have one pair of 300B tubes to use at the moment, the Sophia Electric Classic 300B in blue glass. Any change of input, driver and rectifier tubes is easily recognizable—the clarity of this amplifier reveals the characteristic sound of each tube. I bought the SEWE300B from Decware without tubes, and I found an excellent tube complement from tubes that I had on hand after much experimentation. Having decided on these tubes as a foundation, for the last two weeks I have been listening with enjoyment to new and very familiar musical material, both CD and SACD, and also to LPs. The SEWE300B draws me in and commands my attention, and I am loathe to turn them off and end a listening session. And I’ve suffered no listening fatigue.

I have used the SEWE300B with my Decware ZTPRE and ZBIT and ZROCK2 and really enjoyed the dense, vibrant sound. As the SEWE300B has a built in preamp stage, I spent an afternoon listening to the system without the ZTPRE  preamp. The sound was very nice, I did miss a bit of the density and heft that riding the gain from the ZTPRE provides. I tend to darker, thicker sound overall than others, and it was predictable I’d prefer the ZTPRE in the audio chain, but I am sure others would enjoy sound without it—a preamp is certainly not necessary with the SEWE300B to enjoy deep audio satisfaction, yet another great feature of this amplifier.

The bottom line is: this amp is more than just a keeper, it’s going to be the foundation of my main music system going forward. I’ve sold my SE84UO3 Monoblocks with the 25th Anniversary Mods, something I would not have imagined a year ago. Even though I feel the SEWE300B has a bit more seasoning ahead of it to be all it can be, I’m deeply enjoying its sound and flexibility and thankful to have it for all the hours of listening ahead.

Nice review, Lon.  Thanks for putting these thoughts together.  Your review provides a unique perspective on the 300B, given your history and familiarity with Decware.  It sounds like the 300B either met or excelled at your expectations, which is noteworthy for those who have followed this amp's development and wondered how it might turn out.

Now, if they you could only get your electricity restored.

I too was waiting for this review.  The leap of faith was successful.  Makes my wait only harder! Congrats on finding new sonic bliss as well as finding your monoblocks a new home!

Thanks, Lon.

Randy

I sure will @Tony, though I suspect my review will be on the simple side. I'm really new to this arena and have been chasing a sound quality. I can't really describe it other than to say I really appreciate clear, crisp, and defined. To paraphrase Justice Potter Stewart, I'll know it when I hear it. But gosh, there are so many moving parts ! I listen almost exclusively to vinyl and what a sound is coming out of that little Zkit tonight. Transporting.

Wow, four days! I bet you can't wait to hear you new enchantment maker!

I love and hate how the computer decides what I am trying to say, especially with close ones easy to miss like reveling and revealing. But at least revealing works OK. Really glad your amp is such a pleasure!

Just got power back and took a shower! Relief!

It was really hard to be without music. I wore my laptop battery down listening a bit but it was not nearly as satisfying as listening to any of the three stereo systems.

It's clear that the amp has really begun to bloom. Since the power came back on and my front ends warmed up a day or so I am getting great sound. I did some tube-rolling and at the moment I'm enjoying an Amperex 6085 in the input, RCA Gray Glass 6SN7 with converters as the driver tubes, and an Amperex 5R4WGA rectifier (with an Amperex pinched waist 7062 in the ZROCK2) and getting a rich and silky sound. Wow.

I have I estimate over 600 hours on the amplifier now, and the resolution and depth of the sound have come into a new zone, perhaps its final plateau of travel.

I have a tube complement now that I feel is laid back and spacious, yet not lacking any detail or drive. My front ends have never sounded better either, which has me now enjoying the most profound sound ever.

Here are the tubes in use:

"Sun" labeled Holland made 12AU7
3 75C1 tubes
RCA branded Holland made 7308
Sophia Electric Aqua 274B
Sophia Electric Classic 300B

The team of rectifier and output tubes from Sophia Electric is a very good one, these work together so well. (It's important to note that he ZTPRE has six 6085 tubes with converter bases within it, and the ZROCK2 had a Steve-supplied National 5963 within).

I'm thinking less of the amp right now and just treating the system as I normally would at last, and really. swimming in excellent playback.

I have sold and shipped my Monoblocks so no further direct comparisons are possible.

My conclusions from direct comparison and a five year history with the Monoblocks: To be honest the differences are likely more pronounced in my system as the Monoblocks JUST work with my HR-1 speakers and the sound is shaped by the efficiency of the speakers--giving me a more forward and tilted upward sound than the sound with the SEWE300B which is much better suited with its power for the HR-1 and has a flatter frequency response as a result.

The other difference in "character" between the amps is I think related to the "dual mono" nature, the separate chassis and power supplies. There's a "specificity" to the two channels with the Monoblocks which leqds to just a slightly more chiseled image of an instrument and a slightly more precise left and right and center to the soundstage. The soundfield of the SEWE300B is a bit more center-filled and there's a tiny bit of relaxation to the sound. The fact that there's a preamp stage to the SEWE300B probably also contributes to subtle differences.

What they both share are many characteristics but one prominently: they are very transparent as far as signal purity and each change of tube in the tube conplement is very apparent and the many different ways these amps can sound is fascinating.

Not something I wonder about.

The treble cut circuit made the Monoblocks have the frequency balance I needed, and I did not need more power as a result.

The SEWE300B has plenty of power for my needs and has ended all my "wondering" about other amp possibilities. Now it's more about tubes. Biggest question is about 300B tubes. . . Western Electric? Wathen? Steve says the Wathen has a bit fuller sound, and a bit more bass weight. As shy as I am about ordering from Wathen again, I might.

These updates are exciting and very promising indeed. This will probably be my last attempt at a 300b amp. I'm looking forward to hearing things.

Thanks Lon

Charlie

Your jaw dropping comment reminded me of the UFO25 thread that I read recently and the notion of a jaw holder to prevent injuries and the rendition of what it would look like.  Maybe we need one for Sarah too!

Well I finally decided to try an "audiophile fuse" in the SEWE300B and chose a relatively inexpensive one to try first, the ACME Ag/Cryo Fuse 5A SB 5x20mm CFC Series, from partsconnexion. About 31 dollars including postage.

At first I thought perhaps I had it installed in the wrong direction and that may still be the case, but after about four hours of play the sound has shifted and the frequency balance is less tilted to the high fequencies than initially. I rolled a few tubes and now have an Amperex Holland Bugle Boy 12AU7 in the ZROCK2 again, and a "Sun" labeled Holland 12AU7 in the SEWE300B, a nice slightly warm combo.

It's early to make judgments but I do notice an increase in "punch" -- a dollop of more dynamic shift, and there is a tightening of the attack of notes. I'm listening again (second time this morning) to Betty Carter "It's Not About the Melody" and there's a real precision to the rhythmic sense and a sense of accuracy to each enunciated syllable from this master vocalist.

I have an AMR fuse on the way from Germany to try soon. .. but so far I'm liking this Acme.

It's only been about fifteen hours on this fuse but. .. it's a bang for the buck option for sure.

Now I have Audio Magic M-1 in the PS Audio P15, PST and DSD Mk II, and ZROCK2, and Synergistic Research Purples, in the ZTPRE, so quite some expensive fuses upstream that I heard as each was introduced. The basic ceramic fuse I had put in the SEWE300B was a tiny improvement and it seemed to me listening to the SEWE300B at first that perhaps that was a bottleneck.

This fuse has allowed me to hear a bit more depth to the sound and everything seems a bit more "breathing"--the dynamic information is a bit more pronounced and instrumental images are a bit more chiseled.

It's all about a lessening of noise. Paying attention to the electrical quality in any and many ways is always a good thing. This is a nice improvement from a cheap fuse.