Tubes, tone, and old age.
FWIW, just a short story about how things can change. 30 years ago I had two high power tube amps with SED KT88's. Bought a backup set (or two). Sold amp. What to do with tubes. Nothing, I just put them in a big drawer. Pulled them out every few years and always found them powerful but a tad bright. Never got an amp which served them well and I kinda forgot about them.
I got old. Needed new KT88's. What the hell, I pulled out the old SED's. Interestingly (to me at least) the upper frequency retained its clarity but what was bright in yesteryear, now matched the natural loss of some high frequencies in my hearing due to age. Hog heaven!
Point, if any, to this story is when you go out to buy tubes don't forget that the sound of tubes can and will vary because of the hearing of the seller as well as his knowledge of how they will sound in your system.
Carlsbad2 @llg98ljk Keep whipping that dead horse repeated by ss fans ad nauseum. Maybe you didn't pay attention to my post. I'm whipping no horse, dead or alive. My point is simply that audio perfection would mimic the source. The technology is irrelevant to the discussion. Many people spend inordinate amounts of money and time chasing a sound using a very imperfect instrument. Their ears. |
atmaspher
Yes. Look at distortion vs frequency- if it begins rising much below about 10KHz you will have a brightness problem since higher ordered harmonics will be higher than the THD suggests. The other thing to look at is the distortion profile. Smoother sounding amps have a greater degree of 2nd and 3rd harmonic than amps that tend to sound bright and harsh. This is simply because the 2nd and 3rd in the latter amps is insufficient to mask the higher orders. Our ears interpret the higher orders as harsh and bright using the same metrics that cause tone color in musical instruments. ********************
Thanks that's very interesting. So we can sort of measure these subtle differences but not really. And is the binaural nature of hearing ever part of it? The subtle phase differences of stereo?
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Ralph...this makes me want to if there is a level of distortion below which the increase in THD+N doesn't really matter as far as harshness is concerned?
Some examples might be the Pass XA25 where THD+noise starts to rise at 300 hz but starts from a level of .0015 and then hits .01 by 5khz and .02 by 10khz. Or, another example could be the Benchmark AHB2 where the increase doesn't start until 2khz and starts from .0004 and rises to .001...or the NAD 298 Purifi where the increase starts at 7khz and rises from .003 to .01. (All from Stereophile measurements). None of these amplifiers are usually described as harsh (although some feel the AHB2 or the NAD may be a little sterile)...and yet they all have increasing THD+noise starting below 10kz...and all are predominantly 3rd harmonic dominant.
So, is it possible that if the increasing THD+distortion starts below 10khz...but is at a low enough starting point and is predominantly 3rd harmonic, then the sound might not be harsh...or am I missing something else that could explain this? |
