EL84 6BQ5 Baldwin/SYLVANIA Matched Quad Gray Plates Halo Getter Tubes Made in USA '55

EL84 ( 6BQ5 ) Baldwin/SYLVANIA Matched Quad Gray Plates Halo Getter Tubes Made in USA '55

This matched quartet of Baldwin branded EL84 (6BQ5) tubes produced by Sylvania USA in 1955 represents one of the finest examples of post-war American production.
The construction with gray plates , ring getter (Halo Getter) and compact frame with black base offers an exemplary combination of robustness, tonal balance and dynamic precision .
Baldwin/Sylvania tubes were selected for use in professional audio equipment and high-end electric organs, where low microphonics and absolute electrical stability were required.

Sound Characteristics

• Bass: solid and controlled, with excellent anchoring in the mid-low register; no tendency towards emphasis or resonance.
• Mids: Authentic and full-bodied, with natural timbre and realistic presence of vocals and acoustic instruments.
• Highs: extended but never aggressive, with a refined brilliance typical of 1950s Sylvanias.
• Dynamics: responsive and well-proportioned; excellent microcontrast that enhances detail without being harsh.
• Soundstage: Wide and deep, with stable and coherent imaging; it delivers a sense of three-dimensional realism that is rare in modern EL84s.

🎧 Use in Hi-Fi Amplifiers

Ideal for high-end push-pull or single-ended amplifiers, these Baldwin/Sylvania EL84s deliver smooth, natural musicality while maintaining quiet operation and tonal accuracy .
Perfect in vintage American or European gear (Dynaco, Eico, Leak, Fisher), they deliver a balanced, effortless sonic presentation, with an extraordinarily natural and transparent midrange.

🎸 Use in Music Amplifiers

In the musical field, they offer a harmonious, warm and full sound, with generous headroom and constant dynamic response even under load.
Particularly suitable for Vox AC15/AC30 , Marshall 18W , Matchless amplifiers, or boutique replicas, where their American sound texture provides body, sustain and definition in the harmonics.
The low background noise also makes them excellent for studio recording and professional use .

🎯 Note for Audiophiles and Technicians

A quartet with a noble, warm and natural character, capable of combining timbre precision and authentic vintage charm .

Test Results

Valves tested on Amplitrex AT-1000 Tube Tester
Test conditions: Va = 250 V, Vg = –8 V
100% average value: Gm = 11.3 ; Ia = 48 mA
Test Result: STRONG

• Valve 1: Gm = 9.6 ; Ia = 41.4 mA
• Valve 2: Gm = 10.2 ; Ia = 42.6 mA
• Valve 3: Gm = 9.8 ; Ia = 39.2 mA
• Valve 4: Gm = 9.8 ; Ia = 38.0 mA

Additional Tests Performed:

• Microphonics: Low. Tested and approved for use in hi-fi and guitar amplifiers.
• Output Quality: Excellent – Strong and stable output, no fluctuations.
• Short circuits and GAS: Absent.

Conditions:

• Condition: Vintage tubes - Tested and in perfect working order. Shipped in our custom box for optimal protection.
  
• Functionality: Fully functional.
  
• Aesthetic condition: Very good – Clearly legible writing with minor signs of wear, no obvious defects. See photos for details.
  
• Manufacturing Code: 312 526 → 312 indicates the manufacturer, i.e. Sylvania Electric Products Inc., Emporium, Pa. - 526 → 5 (out of three digits) → 1955 - 26 → 26th week of the year

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