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DevAvidon
24
Apr 7, 2017
It sounds from a lot of the back and forth that there's a fair bit of confusion as to the design goals and purpose of an amp like this, so I thought I'd add my two cents as an owner of two of them. I run a commercial studio in New York, specializing in jazz and classical music production, mixing and mastering as well as post and ADR for film and television. I use the Heron 5 as my primary HPA for tracking and mastering, on account of its genuinely unparalleled technical performance. For those saying this is an inferior amp to something like the Jotunheim, consider the following.
My studio employs a Merging Horus as our primary converters, a 5-figure unit considered among the best and best measuring in the world. The Horus posts a dynamic range of 126db A-weighted. The Heron 5 manages 130db. A-weighted SNR IS 132db. Jotunheim quotes 109. The Horus achieves a flat frequency response within .3db out to 20khz. The Heron 5 manages .2db to 100khz and .05db to 20khz. Most importantly from my perspective, the Horus boasts a 5 degree maximum phase shift as one of its most impressive specifications. Phase linearity across all frequencies is I believe one of most important performance aspects of any high fidelity sound reproduction system, as it translates directly to perceived speed, clarity, soundstage and accurate imaging. Most companies won't even publish their phase deviation specs as they're often as bad as 45 degrees off at points. The Heron 5 manages 2 degrees.
I rely on my Heron 5/HE1000 combo more for fine detail adjustments especially at the mastering stage than even my PSI mains. It is a ridiculously accurate, powerful, fast and transparent amplifier. And my favorite listening combination for pleasure of any rig I've heard is the Heron 5 with the Ebony TH-X00 Fostex cans. This is an endgame amp, balanced outputs or otherwise.
DevAvidon
24
Apr 13, 2017
I'm referring to primary audible band only in regards to their published phase deviation measurements, 20hz-20khz. And I am very specifically referring to in-band phase deviation in common amplifier designs, especially in the 10-20k band and 20-100 band. Flat phase within the audible bandpass is really, really hard to achieve. I've seen 90 degree phase rotation measurements within the Fletcher-Munson band on a couple designs. Remember also phase shift is additive. Not all headphone transducers exhibit extensive phase deviation (piston drivers yes, planars or electrostats often much less so). That said, let’s say maximum shift at the frequency extremes for a high quality transducer is 45 degrees. That’s well within a quarter wavelength and not likely to be hugely problematic. But then lets say the amp rotates another 45-60 degrees in the same bandpass. Now you’re likely to have audible cancellation and artifacts. So I would argue it’s not negligible at all!
To your latter point, not really entirely sure what you mean. The point of trying to achieve relatively flat wideband frequency response is to achieve ruler flat in-band response; this is not like designing a transducer where magnitude deviation can be somewhat arbitrary. You're usually looking at a predictable first order rolloff at the extremes; pushing that rolloff point further out is largely how one achieves in-band linearity. As far as junk up there you don't want to be amplifying, it's either EM or RF noise which this amp does an admirable job of rejecting wholesale or it's aliasing, which one should reasonably expect to be removed by the DACs' LPF when we're talking about this level of technical performance and the sort of chain it belongs in. So in my opinion it's not really the job of the amplifier to limit FR, nor should it reasonably be, as without FIR digital filters, any analog filter employed to limit FR would necessarily induce phase shift, which would defeat the purpose of a flat-phase amplifier circuit. I'm honestly not sure how far the amp goes before F3 but I'm sure it's pretty far up there.
To your final point in your edit, quoted THD+N number is 0.0015%. That is simply not audible; the second and third order distortion of the transducers themselves on most headphone designs is going to be much higher than that. It's also important to remember that this is a very powerful amp - 5 watts into 32 ohms if I recall. Distortion is never a static measurement in amplifier design, it is always relative to power draw.
K.T.N
1264
Apr 15, 2017
DevAvidonThanks for the input, Dev.
It's great to hear from someone who has personal, intimate knowledge of this amp.
Your info makes the anticipation even greater!
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