Huh? Did you perform a blind listening test on this benchmark?
No I haven't JR. But I've done enough DBLTs to bet money that it would sound "cleaner, faster bla bla" than any 100W 8R competitor with conventional PSU.
That is a significant logical leap that PSU alone could predict such a result.
JR, the results of a DBLT tell you what those who aren't deaf prefer. (A good DBLT will have measures in place to weed out the deaf ones too)
The Man in the Street's preference is surprisingly consistent with true golden pinnae. It's the deaf Golden Pinnae who hear "chalk & cheese" that are (totally?) inconsistent.
I can well believe that lots of people (including true golden pinnae) prefer a certain amount of clipping on certain types of music (?!) It's the same phenomena that makes the DJ turn up the music until ALL the lights on the amp flash in time with the music. They equate loud with distortion.
Of course on other types of music, even a very small amount of clipping is detectable and objectionable to most people.
, we found music (???) where clipping 50% of the time was undetectable
When I do DBLTs, the victim ALWAYS chooses the music & playback level.
The type of clean Peavey clipper you describe would appear to make the sound softer cos it 'turns down the volume control'. I've not done DBLTs on this type.
neither have I but single blind tests, using typical listeners revealed a preference for louder over cleaner. PS DDT is not a clipper but fast attack-fast release limiter using OTA for gain reduction.Result of this limiting is less average output power
I have on crude diode soft clippers which tend not to do that but change the character of the clipping. Here, the 'soft clipping' is preferred.
I did some bench work in the late '70s looking at alternate ways to extend headroom by modifying the clipping waveform that was VERY unsuccessful. It sounded much worse than normal clipping (to my unblind single puppy listening test). My design philosophy for recording consoles was to sample at multiple stages of the audio chain so clipping could be completely avoided.
Severe clipping in sound reinforcement is caused by the all to common newbie practice of "not bringing enough rig for the gig". An amplifier driven into hard clipping will put out significantly more average power than when driven conservatively which can drive speakers into power compression (voice coil impedance goes up while overheated leading operator to turn up even more). ETC... Effective clip limiting is most useful for inexperienced operators (i.e. Peavey customers).
Unless you roll PFC into the regulated switcher it's six of one half dozen another as you still have PS caps charged at the mains frequency.
I would expect PFC in any amp SMPS today. Cordell & one or two others talk about this on another forum.
and what exactly did they say? PFC is significantly more expensive than a simple SMPS amp, that just chops the mains voltage at HF to take advantage of smaller magnetics. PFC involves significant front end electronics and has pretty much been ignored after the Euro regulators backed off making it mandatory for professional power amps. Note: PFC in Euro zone is mandatory for consumer products but there are cheaper ways to manage power line harmonics at modest power levels.
Also a reminder that a Class A amp would benefit most from a regulated supply cos
In a class A amp, the same PS ripple is present for low power output as high so not masked by loud audio so arguably more audible and/or dirtier at low level when normal amps clean up. IMO a class D amp that has near zero PSR will benefit the "most" from regulation. FWIW Mark Levinson and probably others used regulated rails in their Class A amps.
[*]amp is smaller so will be overloaded more often[/list]
In line with my philosophy of avoiding audible clipping the use of modest power points seems inconsistent for serious listening. The argument that a low power class A amp allowed to clip sounds cleaner than a larger amp that never clips is dubious, but perhaps a personal preference and I don't argue about what other people hear or prefer.
Not to veer back on topic but I think I now understand why they combined class H with their class A amp. The class A output stage biased up for the same class A current at idle as peak power will sit at idle with huge heat dissipation if the power devices see full PS rail voltage too. By using a modulated rail voltage that only makes the PS available when needed will indeed reduce that signature dissipation that class A amps are notorious for. The rationale for pursuing class A design is to eliminate the turn on-off problems associated with crossover distortion. While a class A output stage will not be subject to crossover distortion, the class H introduces another distortion mechanism associated with turning on and off the rail as needed. So instead of a clean DC PS rail, this design sees large switching components. From their FAB I read that they are using fast MOSFET devices for these PS switches (Just like Hitachi did when they introduced class H decades ago). Note: miller capacitance in bipolar power devices will cause some distortion from modulating the PS rails. I saw this in my old boosted rail design. I had to make my modulated PS fast enough to get there in time for a 20kHz tone bust, but not so fast of an edge rate that the miller capacitance feed through was unmanageable. This trade off compromised how much efficiency gain I could actually realize with acceptable distortion levels.
I posted a hypothetical schematic for a class Ab (big A little b) using my 3 device LTP to keep the power devices from ever cutting off. viewtopic.php?f=6&t=679&start=40#p7907
This "should" completely eliminate crossover distortion without the penalty of excessive heat sink dissipation. I might be tempted to run 1A of class A bias to keep the audiophools happy, but I am not suitably motivated to bread board one up, because amps are already suitably clean enough to not be the weakest link... IMO
PS: I would be surprised if my class Ab hasn't already been done. I think the Japanese designers were looking at something along these lines decades ago. Selling power amps into this market is perhaps more about story than reality. I gave up long ago.
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