There's a good bit of dissing and disinformation about Decware transformers out there.

I think one good source of info from Steve is on pages 10 and 11 of this Decware manual:

https://manualzz.com/doc/37360919/decware-se84ufo-owner-s-manual

What CAJames said. I was recently going through some old threads including when the UFO was launched and the feedback was almost unanimously positive.  I dig the white aesthetic.

The only other mod that seemed to rival the UFO in popularity (or perhaps even more popular) was the Christmas Come Early mod.  I had to reacquaint myself with it after Harley mentioned it in his Torii MKV review.

" I guess to me the biggest reason to be excited about pre-UFO amps is they can be upgraded to a current UFO amp."

Understood fully. But there's also a rich history of people "modding/upgrading" things only to rediscover the magic of original components years later.

part of this curiosity is that there are a few older Decware amps available locally and a 'shootout' comparison is poking me.

I dig the white chassis plate as well. But my new favorite is the SEWE300B color. Gorgeous in person.

"IMHO…once you hear a UFO amp…I don’t think you would want to go back to a pre UFO amp in a side by side comparison."

Valid point of view . BUT ???  do you know how many guitar amp techs in the 70s 80s even 90s  ripped out perfectly healthy Mullards , Brimars , small bottle RCA 6L6's in amps just to 'freshn' up' the amp with a nice new set of new 'pick your country' made tubes? Sure there were some decent current tubes but check prices today to determine what people consider to be 'holy grail'

What if someday?.... people covet early white or gray Decware amplifiers for 'that sound' .  Nothing wrong with having multiple choices in listening tools.

 ..'Many audiophiles are programmed that bigger is always better." Well, hope my way better half never says that to me!  [smiley=beer.gif] All the best everyone~ Mike

Dominick "Matched vs non matched…that’s a separate topic"

are you talking tubes themselves unmatched? or mono blocks with different transformers.

Larger often does seem to be better but smaller has been catching up for awhile now. In a collection of vintage tube amplifiers that sat in my shop ( early 90's ) there were a pair of immaculate pristine Fisher el84 monoblocks ( model 20? 30? ) just sitting there with factory paper tags on them,fully loaded with the stock bugle boys etc etc... not a single person ever asked about them as they were fixated on all the big boys ( 275's , Citation II's , Quads etc ) . I think today that may be a different story.

Was nothing wrong with original OPT´s but many were and are running them in parallel mono and then there is the matching impedance to speakers to take into account... The original OPT´s were designed for lower impedance speakers so finding a good match was not easy. They could drive just about anything at 9.8k impedance but when doubled in mono that drops to 4.9k which is still a bit short of the 3-3.3k that is optimal for a 8ohm speaker to produce low-end.

The original Decware output transformers were and are premium made from OFC on grain-oriented silicon steel cores made in the USA. These premium cores and the fact that the amplifier is designed for 2 watts is why they appear small to so many audiophiles.

Non-grain oriented low grade steel would require nearly double the laminations (size) to achieve the same bandwidth without hysteresis losses which is also known as 'saturation'.  

The difference between original Decware transformers, which by the way are proprietary, and the newer UFO transformers is in the interleaving.  Increased interleaving gave even wider bandwidth and flatter response.

The original transformers came in 9800 - 6 ohm which would drive nearly a dead short since 9800 is almost 3 times higher than needed for the output tube and speaker impedance is reflected backwards through the transformer to the plate of the tube, so as impedance dropped so did the primary impedance of the transformer which allowed the tube to couple more power to the speaker.  Additionally these transformers also came in 3300 - 6 which maximized power into higher impedances.  The amplifiers were ordered with either one or the other.

When bridged into the mono, the output transformer secondaries are wired in series on a Zen Triode amplifier.  This raises the secondary to 12 ohms which now operates with dual primaries and dual cores.  Because a 6 ohm speaker is 1/2 of 12 ohms, each output tube would see a reflected impedance of 1/2 the primary impedance, except there are now two primaries, each taking half the load - same thing as they saw prior to the amplifier being bridged.

The UFO transformers feature a secondary tap that allows us to have both HI and LO impedance speakers at the flip of a switch.