I watched a YouTube review last night regarding my beloved SE84UFO. Not as enthusiastic as others. I replied "I bought this amp in 2016. My path is - Amazon HD Music > Audiolab 6000N > Schitt Bitfrost MB > Decware SE84UFO > Omega high sensitivity speakers. Honestly, anyone can put up all the graphs they want - to me, it's about the sound. This setup sounds AMAZING. I don't know how to describe it like a pro, but I couldn't be happier. Just my opinion as an everyday average "ear"."

https://www.youtube.com/watch?v=6BEQnLnuzao

Yeah, I bought my UFO amps sight unheard, based on the discussions on this site. I watch Youtube reviews, and based on the waiting list a lot of people pay attention to them. But at this point it's people I've met online, at this site and a few others who are the ones I trust, or at least understand. Not someone trying to monetize a channel (not that there is anything wrong with that...).

These are my thoughts while watching the video:


Skunkie Designs

This is someone who “used the tubes that came with it” without actually testing the tubes before measuring the amplifier and then publishing her measurements on her Youtube channel in a "shootout" video with her own lower priced amp.  The measurements would suggest in part tired tubes.  Would be best to have a few new samples of each tube while measuring to see what the range is and rule out any weak tubes.  Almost seems like there was an agenda.



The distortion of the amp is determined by several factors, input voltage, input tube, output tubes, rectifier.  The range at 2 watts is between 2 and 6 % even order harmonic best case / worse case.  So if you’re pushing the 2 watt amp to maximum of 2 watts then you can expect this range.  On a 2 watt amplifier most people are listening with high sensitivity speakers at well below 1 watt which drops the distortion much further. That said this isn’t odd order distortion or high order distortion that we're even talking about and the fact that it makes this person speechless shows a lack of understanding about distortion in general and how it applies to low power triodes because even at the elevated levels it would sound fine, except in the bass where the measurements were simply wrong.

The frequency response test was pretty ridiculous again suggesting several worn tubes or an error in the testing process or equipment because these amps are extended past 70kHz.

The distortion of this amplifier does not vary with frequency by more than 1%. Her measurement system is applying more gain or dwell at 20Hz or has other issues.  To narrow of a spectrum bin depth setting in the software or something like that.

Of course if you set the output taps to the wrong setting the power drops and then if you turn it up, the distortion raises.  Distortion is always linked to gain and load.

There is nothing wrong with even 5% or more of this even order harmonic until the amp is pushed into clipping where you then pick up nasty odd and high order harmonics.  This basic misunderstanding of THD and harmonics is what leads so many people to the buy and sell merry-go-round with amplifiers.  Simplifying measurements, lack of understanding measurements relative to sound quality, measuring incorrectly and then marketing measurements like it’s simple math to the consumer are what fuel this misunderstanding - just choose the lowest distortion and you’ll have the best sound is far from true, yet that is the marketing and sadly it is the same story with the education in electronics amplifier design.

The only facts that are showing themselves are that this person doesn’t have a solid methodology and the testing procedure or software or hardware has some issues.  Even the small amp it was compared to would in reality measure better than it did despite the tiny power supply.

The reality is that at a 1 watt listening level on appropriate speakers the even order harmonic is well within her dream of 2.5% and maintains that from 20Hz to 20kHz with little to no variance.  The higher harmonics are inaudible at twice that level which is what you want.  

In the end I think her disappointment comes from the inexpensive test gear and from tired tubes but time will tell.

Steve

I have all I can do not to reply to the thread again. Minions are lock step. They clearly haven't put headphones on and listened to some of Steve's /Decware Youtube posts. Their loss.

I read some of the comments and its a island of ignorance.

I disliked and talked shit about Tom Waits when I was in high school.... until I actually listened to him. TW is now a King.

Im guessing my older standard Zen ufo has original tubes in it besides the rectifier I replaced myself. 2017 build. I hear nothing that reflects on the Skunksters jabber. It sounds detailed and alive with a good sparkle.

I watched Skunkie’s vid & the recent one posted by Mr. Deckert where he starts with red tipping tubes he selected that pass his standards. Doesn’t look like Steffie is culling any chaff BTW. Aren’t they saying the same basic thing? She had a couple, I think. She came to the conclusion that the amp is for high sensitivity speakers playing at half a watt. The Decware video shows 1/3rd watt with 1 watt peaks as the target power level. Holy Toledo it’s not like dime’in my Marshall (PTL). When I receive my SEWE300B I’ll be into Decware for well north of 10K. So let’s say I have some skin in the game. Right now I’m fooling around with a Z-kit 1 build but want to spurge on some premium iron. At the same time I want to hear what Skunkie’s amp sounds like. Maybe buy one. Life’s too short for all this shade being thrown. Baring National or Worldwide disaster I think Decware will continue to thrive. At Decfest, I listened to different speakers & amps. As much as I wanted it to be a sonic revaluation it was all just part of the journey. Perception of sound (music) is a personal thing. At the same time, I’m still a fan-boy though I’ve been riding tubes since the 70’s.
   There once was a note, listen.   Ralph

"Some things have been happening lately that have made me rethink: Is it time to start limited production of a simple, great sounding single ended amplifier."


LOL exactly ! Someone is tired of their current day job LOL