This change just happened in the 2024 revision, and it was prompted by a comment from our friend Dennis Murphy of Philharmonic Audio
What does Dennis mean that many tube and SS amps cannot meet the 0.1% THD requirement??? I'm confused since I've seen these specs for years.This change just happened in the 2024 revision, and it was prompted by a comment from our friend Dennis Murphy of Philharmonic Audio
For the 1% THD+N change, see SUPPLEMENTARY INFORMATION: III. Analysis of SNPRM Comments and Rule Amendments
For Dennis' comment, see footnotes 21
https://www.federalregister.gov/doc...for-amplifiers-utilized-in-home-entertainment
For example, this amplifier would have zero output if 0.1% THD+N (-60 dB) is used as the limit. So they want the spec to be more lenient so some of these "audiophile" tube amps are eligible for an FCC power rating.
We need to recognize that the "ASR views" are not universally shared. Government regulations (after all, if it is in the CFR, it is US federal regulatory law) should try to keep the majority happy, and should be relevant to the majority. In terms of audibility of distortions and suitability for home entertainment use, IMHO a 1% THD+N limit is more defensible than a 0.1% limit.
I'd say the black line has ~350-375 Watts. I do allow some wiggle there, so it's hard to tell where the actual knee starts. Some amps and some frequencies have rising "normal" distortion when power increases, so the knee is not as pronounced. Maybe the measurement equipment can pinpoint it with higher accuracy, they should know when it's not producing higher voltage.@Jukka, I'm curious ... where would you place the knee for the 9040BA module power curve below for 8 ohms (black line)? From your reasoning, perhaps at 200W, where the distortion starts to rise? Or 300W or 400W, where it definitely shoots up to the skies? BTW, Purifi rates this module at 375W into 8R at 0.1% or -60dB THD+N. As I explained earlier, this is industry standard, and the FCC has not changed it, as far as I can tell. In fact, a manufacturer is free to rate their amp at any distortion level. Purifi would also be correct if they rated their 9040BA module at 200W with -130dB THD+N or 300W with -125dB THD+N. But that would be 'wasteful' and unrepresentative of the true performance of the module.
View attachment 511010
Also, a slight correction to a statement you made: "Harmonic distortion does not, however, make the fundamental (original input signal) any louder (except for H1, if there is such a thing)."
When you look at a 100W (~28.3Vrms into 8 ohms) waveform on the scope at -130dB THD+N, it will be clean. Increasing the power to 200W (40Vrms) or 300W(~50Vrms) at higher distortion levels, the primary waveform amplitude (H1 in this case) will linearly increase and will continue to do so at 200W or 300W. By the time it reaches 375W in this case, the input voltage amplitude will not cause a proportional change in the voltage output, but H1 will continue to increase along with higher harmonic products, just not at the rate as the input (and you'll still see a clean looking voltage waveform on the scope) ... until it just stops increasing when its peak voltage waveform is equal to the module rail voltage (typically +/- 46VDC for this module). Then, a rounded sine wave results, as I explained in my earlier post.
Good and interesting back-and-forth, @Jukka
I've never heard of such a definition. And frankly, it doesn't make sense to me. This would just be equivalent to a non-linear frequency response.
It looks like they put a 10 Ohm NTC thermistor at the input to limit inrush current. Worst case is going to be based on the 264VAC input (373V peak). 373V/10 Ohms~ 37A. With 132V input the max inrush should be about 19A. At 115VAC the peak inrush will be about 16A.
Is this true? LOL, I was going to order this, and I am in US, but I guess I will have to buy the buckeye or the vtv unit, however the apollonaudio unit looks so nice, and has so many adjustable gain options, too bad we have a moron in charge of running the country.
Where did you get the $2500 figure from?
Thank you for noticing this and for pointing it out.
Depends on whether you’re ordering it because you want an audible difference. If you’re after an audible difference, you’re wasting your money. If you’re buying it for a different reason, go ahead.Thanks ! That's a good news ! Just wondering if I take the Sparkos option now that it has decreased by half...
