Saturday 25 July 2020

SUMMER MUSINGS: Post Hi-Res Audio. Why hi-res is often not for the best. Resampling, dithering and de-clipping.

It has been a good summer around here thus far with time off, working around the house, and of course time to enjoy the warm weather for a bit. Here in Vancouver, the late fall to early springs are typically dark and rainy so I'm happy to catch a few photons when I can :-).

With the pandemic, this will certainly be an unusual summer/year. Unless things change substantially, this will be the first year in 2 decades that I won't be traveling off the continent for vacation or work - heck, I can't even visit the USA at this point without at least 2 weeks of self-quarantine back in Canada. In that spirit of staying put and cleaning up this year, I thought I'd talk about a few related items that have been on my mind pertaining to my music library.

A few months ago, I wrote an article about remembering that for home audio, we must always think about the big picture triad of PRODUCTION - REPRODUCTION - PERCEPTION. So often, we in audiophilia spend disproportionate amounts of time on the hardware aspects of reproduction (what's new? how do these devices measure/perform?), or speak of subjective perceptual experiences. Much of that I think is a reflection of what our magazines, online sources, and forum topics revolve around. Maybe that's what the Industry also wants us to think/talk about. We so often forget that in fact, a huge amount of what we perceive - or can perceive - has already been "baked into the cake" from when favourite recordings left the studio (or perhaps specifically the mastering engineer's workstation).

Saturday 11 July 2020

OWNER'S COMMENTS: Pass Amp Camp Amp (ACA) 1.1 by Mitch Barnett

[What follows are comments from Mitch Barnett, the owner of the Pass Amp Camp Amp 1.1s that I listened to and measured. I appreciate Mitch's input on the matter, it's a great example of how owners of the ACA might put them to use in one's system, recognizing one's needs.]

Thanks Arch for the great time with your family for a fun night of good food, wine and of course music and movies. Great job on the objective measurements and subjective listening impressions, “It actually sounds good…” with the caveat of not asking too much from the amp. In my mind, this is the dichotomy between objective measurements versus what sounds good to our ears.

MEASUREMENTS: Pass Amp Camp Amp (ACA) 1.1. The crossroads between objectivism and subjectivism, and reconsidering von Recklinghausen.

Back in 2012, Dana Brock, Nelson Brock, and Mark Cronander (aka Variac) organized an "Amp Camp" in Northern California at the Brock's ranch. Nelson Pass, well known among audiophile circles, contributed with one of his designs and I'm sure they all must have supervised the participants as they went about soldering and building those first kits. The result was a simple, solid-state, Class A amplifier to take home. This amp was of course the Amp Camp Amp (or ACA) which we'll be talking about and measuring here.

You can see Pass' article introducing the amplifier with schematics and measurements. What a great idea! There is no substitute for the value of experience and the memories of building something, especially while sharing with a loved one; regardless of the subjective or objective performance of the final product.

The ACA has developed a healthy following over the years - check out the long-lived discussion thread on diyAudio. Nothing official, but I heard over the grapevine that there have been >2000 kits sold, suggesting conservatively >2500 actual stereo amps out there with no accurate way to estimate non-kit PCBs, unofficial "clones", or just completely DIY builds with the published schematics.