5% THD to .000 THD SOUND

yogiboy
1,321 posts
07-31-2016 7:02am
How would you know that a manufacturer is not fudging the specs ? If an amp is not reviewed and tested you would never really know if the listed specs are accurate.
Just sayin’

good point, but I doubt they would be quite so bold, you know, what with audio magazine reviewers who do measure amplifiers for THD among other things. It probably wouldn’t be too good for business if it turned out they fudged the specs. And if the amp mfgr intends to be a viable business he needs reviews, no?  But more to the point, we (editorial we) found out almost 40 years ago that THD specs are meaningless. That was when certain amplifiers with exceptionally low THD sounded terrible and certain tube amplifiers with relatively high THD sounded sublime. So, this debate was actually concluded 40 years ago, regardless of it’s troll appeal over the years. Amps won’t sound the same in different rooms and different systems, anyway. There are too many variables.

Well said.

derrickengineer OP
31 posts
07-31-2016 3:16am
geoffkait3,776 posts07-30-2016 4:58pm

"I went out for a mild mannered troll and got a sucker on the line."

to which drrekengineer replied,

"Well since you said it mr. kaits, is there a bit of quilt coming out from your magic clock thingy or by stating " got a sucker on the line" you know full well there's nothing magic about your magic clock? 

That was almost a complete sentence. When you cast the bait out there you never know who's going to bite. - old audiophile expression

:-)

This is an interesting topic personally as I’ve had the opportunity to hear the Kondo Kagura at CES a couple of years ago. It was in the context of an all Kondo system to best of my knowledge. Verdict, superb natural sound is what I experienced. Pure,clean and transparent with full body tonality and harmonics.

Derrickengineer where did you see/verify the THD specification of 5%? That seems high and I wonder how that was measured. I believe that the Kagura has a switch to adjust NFB levels (output impedance ). I recognize that 2nd order distortion is congruent with nature and is readily tolerated by human hearing (unlike upper order odd distortion ) , Ralph (Atmasphere ) has clearly and thoroughly covered this subject very well on several occasions.

I’m skeptical about the 5% THD stated by the OP based on what I heard. There wasn’t a hint of an euphonic, colored , overly warm character at all. Stings,brass,woodwinds and piano were exceptionally realistic in presentation. Shortly after this listening session I visited the Pass Labs room,. This consisted of the XS 300 amplifiers driving the Marten Coltrane (Supremes I believe ). Without question the XS amplifiers will spec at much lower THD than the Kagura.

IMO the Pass and Marten combo was quite good but this system lacked the tactile flesh and blood realism compared to the Kondo suite. I was more aware of the fact of listening to a fine collection of electronic audio components. In contrast the Kondo seem to put me in the presence of live musicians. The two systems were very distinctly different. However the THD is determined there is certainly more to this story that is unexplained with numbers /measurements. Bottom line, the Kondo system was more emotionally engaging and convincing in that it simply pulled me deeper into the music.

My gut feeling is that although the Kagura has higher THD than the esteemed Pass XS 300 I suspect that the number is very likely less than 5% as reported by the OP. This is just my opinion after listening to these two ultra expensive systems virtually back to back. Inna is right, you just have to actually listen to components and decide based on what you hear. That’s why YMMV will always ring true. That Einstein quote posted by Eric is so on the mark.  Audio components are built based on science and engineering principles  no doubt whatsoever,  yet there is a genuine component of "art" at play as well. We can clearly hear things that can't be fully explained at this juncture. 
Charles,

Charles, you raise a good question about the 5% THD number. I looked into it a little, and as you can see here, near the bottom of the page, that is what the manufacturer specifies. And that set of specs is quoted in various reviews.

As I’m sure you realize, the Kagura is a SET amplifier utilizing a parallel pair of 211 tubes. In looking further, I found datasheets for some incarnations of the 211 stating operating conditions in class A audio frequency applications that include an output power (per tube) of typically 12 watts **at 5% second harmonic distortion.** See the following:

http://www.tubeampdoctor.com/images/File/ER-211%20Datasheet.pdf

http://www.diyparadiso.com/datasheets/211-vt4c.jpg

I’m just speculating, of course, but perhaps the manufacturer wanted to release specs prior to concluding developmental testing and/or evaluation of a meaningful number of production units, and therefore simply chose a very conservative number that they could feel completely confident would be met. And perhaps they chose that number simply based on what appears in the 211 datasheet.

On the other hand, though, the 5% number in the datasheets is just second harmonic distortion, so presumably a corresponding spec for THD would be at least slightly worse. And the fact that the Kagura’s 50 watt power capability spec reflects 25 watts per tube, rather than the "12 watts typical" indicated in the datasheets, would also seem to suggest that the 5% THD spec may not be all that conservative.

Regarding your and Inna’s philosophy that "you just have to actually listen to components and decide based on what you hear," I of course agree (aside perhaps for the word "just"). However there is only so much equipment that any individual will have an opportunity to hear, i.e., that can be put on his or her short list. Given that, my own philosophy is why take chances by including on a short list components for which there is cause for concern, whether it be due to specs, published measurements, widespread controversy about its sonics, excessive criticality of system matching or setup, manufacturer reputation for customer service and support, or any other such factor. Especially if the short list indeed needs to be "short" in a particular case, or if an audition needs to be relatively limited in scope or duration.

Simply put, my preference is to play it safe when it comes to deciding what to short list. But that is just my own preference, and I don’t consider it to be any more valid or less valid than anyone else’s approach.

Best regards,
-- Al