The ABH2 works with European voltage, 220v, or a non-US version is needed?.
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The ABH2 works with European voltage, 220v, or a non-US version is needed?.
2015: https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifierFolks, this amplifier got reviewed when it came out in 2016 and the news of it got lost literally in the noise. Let's not let that happen to it again with this review. People need to know about exceptional audio products and the Benchmark AHB2 is one of those.
The ABH2 works with European voltage, 220v, or a non-US version is needed?.
I admire this amplifier, but I have two questions:
1 Will it handle electrostats, and my Quad 2805s in particular?
2 Will the impressive measured performance translate into audible superioity compared to, say, a Quad QSP?
There are some very interesting short articles on the amp on Benchmark's website: https://benchmarkmedia.com/blogs/application_notes/tagged/ahb2AHB2, not ABH2... From the Benchmark website:
A.H.B.
The letters A, H, and B allude to the unique topology of the amplifier's output stage. The AHB2 combines class-AB, and class-H topologies using a feed-forward error correction system.
But there is much more to the story -
The initials A.H.B. can be found on many of the circuit diagrams of Benchmark's early products dating back as far as 1983. These are the initials of Benchmark's founder, Allen H. Burdick. He personally designed many of Benchmark's early products.
Allen had a life-long passion for audio, and he became one of the leading innovators in the pro-audio industry. The AHB2 is named in his memory.
I think this generally refers to the phase the harmonic has when the fundamental phase is zero. Since the harmonics are multiples of the fundamental they will be back to the same relative phase when the fundamental starts its next cycle, though will have been through 'n' cycles of their own. Different distortion mechanisms produce different harmonic phases. Here are examples of 10% 3rd harmonic with phase 0 (which starts to look square, as one might expect) and with phase 180 degrees, which is quite triangular. What either has to do with "depth" is beyond me, though.I am maybe stupid but I struggle with the concept of an out of phase odd harmonic. Surely, even if it is out of phase for the first cycle of the fundamental it will be in phase for the second and so on?
Are we saying we can tell which cycle of the fundamental is in phase with the harmonic and which isn’t, or is it bollox?
Feedforward compensation has been around "forever" and I have often used it in a design. I am not sure it has been applied to audio amps before, though I have a vague memory of seeing it back in the 1980's.
I think Denon used it in their non-NFB amps in the 90s, @restorer-john should have more insight.
Q24-Q27 is the correction amp - correct?Sansui loved their "super feedforward" AU-Dxxx series in the early 1980s.
AUD-11 implementation:
View attachment 26729
Here is the schematics of the Quad 405 and the service manual.I think the most famous would be the Quad 405 from the 1970s.
These sweeps start at 20 kHz and go down so the amp has been enduring full power at higher frequencies for 30 seconds or more prior to it shutting down this way.Whats with the amp going into protection mode at only 133W@4ohm @45hz? You telling me if i play something from a bass guitarist at nearly full noise it will keep shutting down? I thought it was rated at 190w at 4ohm.
It's already supremely difficult to tell the difference between amplifiers that are in the 0.01% (-80dB) and 0.001% (-100dB) ballpark in tests designed to reveal distortion. Most would argue it's even inaudible for music. Even some of the most excellent loudspeaker drivers have distortion components around 0.01%.
Ahh - so these power ratings published by benchmark are also not continuous as per the (insert standard here), as per the similar discussions in the hypex NC400 thread? Im not bothered whether the are or arent, just pays to be transparent.
Does it mean that valve amps, ~0.1% distorsion (-60dB), are not suitable for classic music, specially orquestral, since they are fully unable to reproduce much of the dynamic range?.