Very interesting, thanks! The change in D2 for the HD600 doesn't look too bad. Based on what I'd heard/read about tubes, I was expecting worse! I've always wondered if a properly designed tube amp would still have a noticeable increase in harmonic distortion (again, based on what people have told me about tubes and distortion), and that does not look to be the case. (This is not a topic I know too much about, so excuse my ignorance!)
Quote from: hans030390 on August 06, 2013, 11:26:00 AMVery interesting, thanks! The change in D2 for the HD600 doesn't look too bad. Based on what I'd heard/read about tubes, I was expecting worse! I've always wondered if a properly designed tube amp would still have a noticeable increase in harmonic distortion (again, based on what people have told me about tubes and distortion), and that does not look to be the case. (This is not a topic I know too much about, so excuse my ignorance!)Keep in mind that the Vahalla is on the extremely low end of tube amps. I saw no significant differences between measurements from the BA or the O2 when taken at the transducer level. Yes, tube amps do have more distortion than discrete solid-state than chip solid-state. But such distortion is still a magnitude or more lower than that distortion from a transducer.
I am not familiar with Schiit Valhalla but seems like its just the output tubes running out of steam for the Low Z load that the HD598 presents.
While the ratio is linear, the transfer function it describes is second order harmonic oscillator.As in here, zeta (ΞΆ) is the damping coefficient: http://en.wikipedia.org/wiki/Damping_coefficientTransistors, diodes and vacuum tubes can be reasonably well described in V/I by two second order functions, one for positive part, the other for negative. (The correct one is actually exponential.)
I have always noticed that the hd555/595/558 that I owned would never sound good out of integrated amps or OTLs. It maybe the impedance curve crossing over from low impedance all the way to around 250ohms
Keep in mind that the Vahalla is on the extremely low end of tube amps. I saw no significant differences between measurements from the BA or the O2 when taken at the transducer level. Yes, tube amps do have more distortion than discrete solid-state than chip solid-state. But such distortion is still a magnitude or more lower than that distortion from a transducer.
GJ Ultrabike! I've often thought of synergy as 'reactance' and one can clearly see why here. There's much more going on here than taking a thin/bright phone and pairing it w/ a warm/lush amp. That's the basic type of synergy people tend to strive for.
Yeah, there's much ink spilled on the damping factor significance, but I haven't been able to find a sufficiently simple explanation for me to comprehend. Also I'm unsure if the explanations I've come across extend to directly driven single driver solutions as much as multi-driver crossover systems.
The fact that it is a non-feedback design with a low current tube output stage (I reckon) won't help in linear behaviour of the output stage at higher currents though but a 15dB increase in 2HD is a bit much and can't be contributed to a slightly higher current alone. IM distortion might also give some clues.
The FR differences are caused by the relatively high output R of the amp and occurring voltage division. The fact that the HD558 sort-of depends on electrical damping as it is intended to be fed from low output R amps will also increase THD. Damping factor could play a role in this particular case.The fact that it is a non-feedback design with a low current tube output stage (I reckon) won't help in linear behaviour of the output stage at higher currents though but a 15dB increase in 2HD is a bit much and can't be contributed to a slightly higher current alone. IM distortion might also give some clues.
Tubes has less higher order distortions and do not generate as much complex(spikes as opposed to smooth curves) distortions as SS ones do? Theres a Pass article on this that is on 6moons as well, also related on NFB which objectivist love so much.
