Performance Testing Protocols

We used a testing protocol that allowed for a systematic, hybrid method for setting cartridge azimuth − the left−right rotational alignment of the stylus in the groove − by combining mechanical alignment, electrical measurement via a Fozgometer, and critical listening with musically revealing program material. The goal: minimize crosstalk, maximize phase coherence, equalize groove wall contact, and optimize stereo imaging and soundstage, tonal purity, and high-frequency smoothness.

Correct Azimuth sounds like:
∙ Smooth sustained harmonics, natural HF air
∙ Precise spatial localization & depth
∙ Increased low-level detail retrieval
∙ Higher perceived resolution without harshness
∙ Maximum center focus
∙ Reduced listening fatigue
∙ Minimum crosstalk, repeatable results

The Fozgometer finds electrical symmetry.
The music finds perceptual truth.
True azimuth is where both agree.

Azimuth Calibration Testing Protocol

Stages 1–3 establish mechanical and electrical baselines: set VTF, VTA, and visual azimuth, then use the Fozgometer with a test LP to minimize crosstalk and equalize channel leakage through very small incremental adjustments.

Stages 4–8 are critical listening passes − mono lock-in, music verification, channel symmetry, stereo imaging, and high-frequency stress testing − each refining position by ear around the Fozgometer-derived setting.

Stages 9–10 re-confirm electrical measurements, verify alignment convergence with listening results, lock the setting, and re-check VTF/VTA for stability.

Cartridges
For the initial comparative listening tests, a variety of cartridges were used for testing diversity:
1. Audio Technica AT33PTG/II
2. Ortofon Kontrpunkt b (upgraded by Joseph Long with a Fritz Gyger S stylus and a boron cantilever)
3. Denon DL-103R (upgraded by Joseph Long with a Nude 5/75 line contact stylus, and hardened tapered aluminum cantilever)
4. Hana Umami Red

Reference Recordings
Evaluation tracks were selected on the basis of tonal diversity and deep resonance of selected tracks.
1. Pink Floyd, Dark Side of the Moon (1979 pressing)
2. Dire Straits, Brothers in Arms (Mobile Fidelity Sound Lab)
3. Joni Mitchell, Court and Spark (Nautilus Records UNAU 11)
4. Joni Mitchell, Don Juan’s Reckless Daughter (Overture, Cotton Avenue tracks)
5. David Crosby, If I Could Only Remember My Name (Mobile Fidelity Sound Lab, Ultra Disk)
6. Ricki Lee Jones, Gravity (1979 pressing)
7. Eagles, Hell Freezes Over (Hotel California track)
8. Steely Dan, Aja (1979 pressing)
9. Simon and Garfunkel, Bridge Over Troubled Water (Mobile Fidelity Sound Lab, Ultra Disk)

Turntable | Tonearms
Technics SP-10 with a Unified Theory UA-101 tonearm, and custom AST stabilizer for the AX-1 armboard.
Micro Seiki DDX-1000 with a Unified Theory UA-101 tonearm, and custom AST stabilizer for the AX-1 armboard.
Micro Seiki DDX-1000 with an upgraded Audio Technica AT-1010 tonearm (upgraded by Angus MacDonald, UK), and custom AST stabilizer for the AX-1 armboard.

Results
Objective (Instrument-measured)
1. Left-to-right channel crosstalk level (dB of leakage)
2. Right-to-left channel crosstalk level
3. Crosstalk symmetry (balance between L→R and R→L leakage)
4. Channel output level balance (equal amplitude from L-only and R-only test tones)
5. Phase correlation between channels (in-phase vs. out-of-phase signal content)
6. High-frequency crosstalk at 10 kHz
7. Channel separation at 1 kHz
8. Vertical tracking force stability (measured before and after adjustment)
9. Stylus rake angle / vertical tracking angle measurement
10. Mechanical azimuth angle (visual or measured deviation from perpendicular)

Subjective (Critical Listening)
1. Center image focus and solidity (phantom mono lock)
2. Stereo image stability (freedom from lateral drift or wander)
3. Harmonic smoothness on sustained tones (absence of grain or "spit")
4. High-frequency air and openness (sweet vs. sharp/etched)
5. Breath noise naturalness on flute (integrated vs. harsh or exaggerated)
6. Tonal symmetry across channels (no brightness or texture shift when panning balance)
7. Soundstage depth, width, and layering clarity
8. Transient cleanliness on cymbals/piccolo (shimmer vs. splash)
9. Listening fatigue level (ease vs. tension over extended passages)
10. Low-level detail retrieval (subtle spatial and harmonic cues emerging naturally)

The testing protocol's main philosophy is that these two lists should converge − the Fozgometer gets you into the right zone, then your ears confirm and fine-tune within it. When measurements and listening impressions point to the same setting, you've successfully optimized your system.

(to be updated)