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RCA

5693 ( CV3699 ) RCA NOS SPECIAL RED AMPLITREX Matched Pair Tubes MADE IN USA '52

5693 ( CV3699 ) RCA NOS SPECIAL RED AMPLITREX Matched Pair Tubes MADE IN USA '52

€149,90 EUR
€149,90 EUR
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5693 ( CV3699 ) RCA NOS SPECIAL RED Matched Pair Tubes MADE IN USA '52

AMPLITREX Tested – VERY STRONG

General Description

This extraordinary pair of 5693 (CV3699) RCA NOS "Special Red" tubes, manufactured in the United States in March 1952 (same date codes 3-52), represents one of the most iconic and sought-after versions of the 6SL7 family.

The 5693 Special Red series is universally recognized for its selected construction and superior quality standards compared to standard versions. The characteristic red coating is not only a distinctive aesthetic element but identifies a special production, designed to ensure greater stability, durability, and reliability over time.

This pair stands out for:

  • RCA USA – 1950s production
  • 5693 / CV3699 – selected special version
  • "Special Red" body
  • Same Date Codes 3-52
  • Matched Pair NOS

This is an NOS matched pair, tested and perfectly consistent, with perfectly matching electrical values between the two units, an element of great technical and collectible value.

A top-tier offering, combining historical prestige, selected construction, and reference sound performance.

Sound Characteristics

Bass

Deep and controlled, with a solid and authoritative structure that brings balance to the soundstage.

Mids

Rich, refined, and three-dimensional. Vocals emerge with great naturalness and presence, with an extremely elegant harmonic texture.

Highs

Sweet and silky, with natural extension and always fluid, never fatiguing rendition.

Dynamics

Linear and controlled, with extremely stable and consistent response.

Soundstage

Wide, airy, and well-focused, with excellent separation and credible depth.

🎧 Use in Hi-Fi Amplifiers

Ideal for:

  • high-end preamplifiers
  • input stages
  • systems where maximum stability and consistency are required

Thanks to the Special Red selection, they offer extremely reliable behavior, with refined and controlled sound performance.

🎸 Use in Musical Applications

Perfect for:

  • tube preamplifiers
  • quality instrument amplifiers

They offer:

  • balanced dynamic response
  • great definition
  • elegant and musical sonic character

🎯 Note for audiophiles and technicians

  • RCA USA – year 1952 (same date codes 3-52)
  • 5693 / CV3699 – Special Red
  • Selected Matched Pair NOS
  • Perfectly matching values between the two units
  • VTT Classification: VERY STRONG

A pair that represents not only a technical choice but a true cult object for enthusiasts and collectors, capable of offering a refined sound experience and a unique aesthetic presence, in the full style of the great American tubes of the 1950s.

Test Results:

Tube tested on AMPLITREX AT-1000 Tube Tester:

  • Test Conditions: Va = 250V; Vg2 = 100V; Vg = -3V 
  • Average 100%: Gm = 1.6 ; Ia = 3.0 mA
  • Test Result: VERY STRONG

Tube 1: Gm = 1.5 ; Ia = 2.7 mA

Tube 2: Gm = 1.5 ; Ia = 2.7 mA

Additional Tests Performed:
  • Microphonics: Low. Tested and compliant for hi-fi use, including phono stages and guitar amplifiers.
  • Emission Quality: Excellent – Very strong and stable emission, without fluctuations.
  • Shorts and GAS: Absent.

Conditions:

  • Condition: NOS - New Old Stock - Tested and functional - Supplied in our custom box for optimal protection. 
  • Functionality: Perfectly operational, with excellent test results.
  • Cosmetic Condition: Excellent – Markings excellently preserved, minimal signs of age. See photos for details.
  • Manufacturing Code: 3-52 → RMA/EIA Open Date Code → manufactured the 52nd week of 1953 → Radio Corporation of America, Camden, N. J.

Discover why our tubes are different →

Terms of Sale & Safety

Sales Terms & Product Safety

Each vacuum tube is carefully selected, tested, and verified in our laboratory before shipment. Where stated in the listing, test results, matching data, and declared characteristics refer to measurements performed using the specified test equipment and operating conditions.

Sound descriptions are provided for guidance only and reflect the characteristics generally associated with that particular tube type. Personal sound preferences, tube rolling, or perceived differences between audio systems do not constitute a product defect.

Before installation, please verify the tube’s electrical and mechanical compatibility with your equipment and follow the manufacturer’s instructions.

New production and NOS tubes are shipped with a tamper-evident security seal and internal technical documentation to ensure traceability of the product’s condition at the time of shipment.

Product Safety (GPSR)

Vacuum tubes are electronic components intended exclusively for use in compatible equipment and must be installed in accordance with the equipment manufacturer’s instructions.

Due to their historical or vintage nature, certain technical specifications may be based on original datasheets or equivalent technical documentation when documentation from the specific manufacturer is unavailable.

Use only with suitable equipment. Keep out of reach of children.

Shipping & Returns

Shipping & Returns

We ship worldwide using carefully selected express carriers and protective packaging specifically designed for vacuum tubes.

If you change your mind, you may exercise your right of withdrawal within 14 days of delivery, where applicable under the relevant consumer protection laws. The product must be returned complete with its original packaging and accessories, in the same commercial condition in which it was received. Return shipping costs are the responsibility of the customer.

Every returned item undergoes a technical inspection. Installation, use, tube rolling, or any other handling may reduce the product’s commercial value and may affect the refund amount, in accordance with applicable law.

If you believe the product has a lack of conformity, our laboratory will carry out the necessary inspections and apply the remedies provided by the applicable consumer protection legislation.

For further details, Customers are invited to consult the “Terms and Conditions” and “Refund Policy” sections of our website, or to contact us before placing an order.

Vacuum Tubes Treasures
www.vtt.store | www.vacuumtubestreasures.com
📧 info@vacuumtubestreasures.com

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  • ATTENTION PLEASE

    Please understand that the writing on the glass of vintage valves has become very delicate over the years and comes off easily. You must handle them with extreme care to avoid this. Wear and damage to the writing on the valves reduces their market value and causes damage. Please exercise extreme caution.

  • ATTENTION PLEASE

    We wish to inform you that any attempts to manipulate shipping destination information in order to obtain lower shipping rates may be considered fraudulent acts. Please provide accurate information and contact us if you have any concerns. We reserve the right to review and, if necessary, cancel orders that we deem to be in violation of our conditions. Thank you for your understanding and cooperation.