I've made no claims to being an expert listener, or even that my AB testing is accurate. I have simply stated my findings as a designer / manufacturer of top-end audio recording gear over the last 30 years. The fact that we are the leading analog front-end for the world's most critical recording applications (film scoring, classical music, sample houses, archiving, etc.) could be a wild coincidence. I really don't know. Think what you wish.
This might be helpful. I'll share the story of how the company got started. It's tightly aligned with AB testing.
I started building audio gear when I was 12 years old. Guitar amps and pedals mostly (have played instruments since 5 years old). By the time I left high school, I had built a near-complete recording rig: preamps, EQ, mixers, etc.. with mentors such as the Burr Brown OpAmp handbook and Walter Jung. After Cal Poly, I spent close to 10 years in the Silicon Valley. Was one of the 3 original startup employees at Multitech USA, and grew my division to be the world leader in OEM PCs -- licensed to IBM, NEC, etc. We changed the name to Acer America, and I left the company in 1989.
After Acer, I wanted to return to my audio passion, so I started producing classical music recordings around Northern California. Did this for 25 years, mostly symphony orchestra and chamber music recordings. Easily 500 symphony recordings (I lost count), probably closer to 1000 total recordings. Very early on (1990), I realized that my purchased recording equipment was not giving me the highest sonic performance, so I set about to design my own.
I spent about 1.5 years experimenting with micamp designs, constantly iterating, trying new active and passive devices, layout topologies, architectures, and so forth. This is when I first developed an AB listening test strategy. I used a B&K high voltage microphone (mono) and recorded "difficult sources" such as bell tree, jingling keys, and my own voice. I recorded each trial test into my well-aligned multit-track tape machine at 30ips, no noise reduction. Its usable FR extended to 40kHz. I then played back each trial thru a box that I designed that allowed me to "self-blind" the test. I didn't know which signal I was listening to w/o looking back at the box. I learned fast that AB levels must be -precisely- aligned (no more than 0.02dB differential) to do a valid AB test.
After 1.5 years of circuit iterations and AB testing, I got the circuit as neutral and timbre-correct as I could make it. It turned out to be an extensive variation on Grahame Cohen's seminal "double balanced" design at Philips Microelectronics. I've shared his papers with countless souls over the years -- his was a brilliant breakthrough in audio signal path. He recently passed away.
Anyway, I kludged up 8 channels of my final design and started using it for my remote classical recording work. It was like night and day compared to my former "store bought" signal path. Just gorgeous. I was elated.
Around this time, my friend who recorded the San Francisco Symphony (Jack Vad) heard about my micamp design. He asked to borrow some channels, so I lent them. He called back a couple weeks later, asking me to build him 8 channels. So I did, in my garage. Not long after, I got another call from an L.A. classical music producer asking to build him some channels, simply on Jack's advice. Around this same time, Jack told the editor of a top pro audio magazine (Nick Batzdorf) about my micamp design. The editor called me and said, "we're doing a comparison shootout of top outboard mic preamps and Jack said we should check yours out." He continued, "don't worry, if it doesn't do well in the test, we'll not mention it."
So a couple months went by, and then he called back. "You know, your mic preamp was, hands down, the best sounding preamp of the 8 others we tested." That review was written up in Recording Magazine, and I immediately started getting orders, opening dealers, and starting a real company. Our first dealer was Sam Ash Music in NYC (David Prentice). Today we have over 100 dealers and distributors, worldwide. That sames HV-3 microphone preamplifier was recently inducted into the Technical Hall of Fame (2019) ......
Write-up in Forbes.
That's the foundational story, and that's how I learned to do blind AB testing. I've continued to refine my art of AB testing over the last 30 years. Today's method is far better than the old multi-track days. And, like you, I'm still learning, still growing, often being humbled by my lack of knowledge, or being proven wrong by real science. Heck, just the other day I was adjusting a 14k EQ bump for a little extra air (DAW). I turned the knob slightly and heard the air I wanted. Then I looked down at the screen and realized the EQ band was OFF.
Audio can fool you. Science never lies.
