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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

¥1,211.00 CNY
¥1,211.00 CNY
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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 →

Condizioni di vendita e sicurezza

Anti-Tamper Security Seal Policy:
Each product is sealed to guarantee quality and integrity.
The right of withdrawal is subject to the seal remaining intact, as provided for by the Consumer Code.

Eco-Friendly Packaging:
The tube will be shipped with protective packaging to ensure safety during transport.
We use recycled and recyclable paper for packaging, along with brown ECO-KRAFT adhesive tape, eco-friendly and solvent-free.

Important Notes:
This tube, manufactured according to the standards of its era, is designed to operate in equipment compatible with vintage tubes.
It is recommended to follow standard safety guidelines to avoid malfunctions or damage.

Safety Assurance:
Although not tested according to modern GPSR regulations, this tube was designed to operate safely under the conditions for which it was manufactured.
We recommend using it only with equipment that supports vintage tubes, in order to avoid risks of malfunction or damage.
Technical data note:
In some cases, the technical data provided may be based on datasheets from other manufacturers or on equivalent historical specifications, when a specific official datasheet for the production batch of the listed item is not available.
Electrical characteristics may vary slightly depending on the production batch and manufacturing period, as is typical for thermionic components.

Safety Information:
Warning: Keep out of reach of children.
To be used under adult supervision.
Use the product only with equipment designed for vintage tubes.

Shipping & Returns

Shipping & Returns

Shipping Costs

Shipping costs vary depending on the total amount of the items in the cart and are calculated automatically during the checkout process.
All shipments are fully insured. The courier is automatically selected based on destination, weight, and shipment characteristics.

Shipping Times and Delivery

The indicated delivery times are purely indicative.
Any delays, storage issues, or operational changes made by the carrier (for example during peak periods such as holidays) are not attributable to Vacuum Tubes Treasures.

In such cases, we will nevertheless provide the Customer with all necessary support to open claims or assistance requests with the appointed courier.

International Shipping (Non-EU Countries)

For orders shipped to countries outside the European Union, any customs duties, import taxes, or additional charges are the sole responsibility of the recipient.
Vacuum Tubes Treasures has no control over these costs, which may vary from country to country. Customers are therefore advised to contact their local customs authorities prior to placing an order.

Warranty

All products sold by Vacuum Tubes Treasures are covered by the legal warranty of conformity, in accordance with Italian Legislative Decree No. 206/2005 (Consumer Code) and the Italian Civil Code (Articles 1490 et seq.), under the conditions set out below.

Warranty for Vacuum Tubes

Vacuum tubes, being components subject to wear and of vintage or specialized nature, are covered by a specific warranty of 6 (six) months from the date of delivery.
The warranty covers exclusively proven manufacturing or conformity defects that arise during proper use in accordance with technical specifications.

The warranty does not cover:

  • normal wear and tear,
  • subjective sound preferences,
  • use in incompatible equipment,
  • tampering or improper use.

Right of Withdrawal

Purchases made on the Vacuum Tubes Treasures website are governed by Italian regulations on distance contracts (Legislative Decree No. 206/2005).

Consumers have the right to withdraw from the contract within 14 (fourteen) days from the date of receipt of the goods, without providing any reason.

Conditions for Exercising the Right of Withdrawal

The right of withdrawal may be exercised only if:

  • the product has not been used,
  • the product is returned in its original condition,
  • the tamper-evident security seal is intact and not broken.

📌 Returns are not accepted for reasons related to sound preference, tube rolling, or subjective audio evaluation.
As with a music recording, a vacuum tube cannot be returned simply because its sound does not match personal taste.

Effects of Withdrawal

In the event of a valid withdrawal:

  • all payments received, including standard shipping costs, will be refunded,
  • refunds will be issued within 14 days from receipt of the returned goods,
  • the refund may be withheld until the goods have been received and inspected.

Refunds will be made using the same payment method used for the original transaction, unless otherwise agreed.

Return Shipping Costs

Return shipping costs are borne by the Customer, except in cases of:

  • verified defective products,
  • errors attributable to Vacuum Tubes Treasures.

In such cases, return shipping costs will be fully covered by us.

Damaged or Incorrect Items

If the Customer receives a damaged or incorrect item, it must be reported within 5 (five) working days from delivery, by email or telephone, clearly stating the issue.

Uncollected Parcels, Storage, and International Shipments

It is the Customer’s responsibility to monitor the shipment and promptly arrange for collection or customs clearance.
Any costs, delays, or losses resulting from:

  • failure to collect the parcel,
  • prolonged storage,
  • abandonment of the parcel at customs,

do not entitle the Customer to any refund.

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.