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RCA

6SN7 GTB RCA Red Logo AMPLITREX Matched Pair Black Plates D Getter Low Noise & Mic Tubes

6SN7 GTB RCA Red Logo AMPLITREX Matched Pair Black Plates D Getter Low Noise & Mic Tubes

654,00 RON
654,00 RON
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6SN7 GTB RCA Red Logo AMPLITREX Matched Pair Black Plates D Getter -  Made In USA - 1960s

Bridge Filament Edition

AMPLITREX Tested – VERY STRONG – Low Noise & Microphonics – Vintage American RCA Production

Test Results:

Tubes tested on Amplitrex AT-1000 Tube tester:

  • Test Conditions: Va = 250V, Vg = -8V
  • Average 100% Gm = 2600 ; Ia = 9.0 mA
  • Test Result: VERY STRONG

Tube #1

  • Section 1: Gm = 2800 ; Ia = 10.2 mA
  • Section 2: Gm = 2500 ; Ia = 9.0 mA

Tube #2

  • Section 1: Gm = 2600 ; Ia = 10.0 mA
  • Section 2: Gm = 2700 ; Ia = 8.8 mA

Additional tests:

  • Burn-in / Stability Test: 48h – OK
  • Microphonics and noise: Low. Tested and compliant for use in hi-fi equipment and guitar amplifiers, including the most sensitive audio stages.
  • Balance: Good. The sections present a consistent balance, fully compatible with use in hi-fi and musical amplifiers, in all applications where absolute symmetry between the sections is not required.
  • Emission: Excellent – Very strong and stable emission, without fluctuations.
  • Short circuits / Gas: absent

Description

Selected vintage pair of 6SN7GTB RCA Red Logo – Bridge Filament Edition, produced in the United States in the 1960s and carefully matched as a Matched Pair. Both specimens feature the characteristic Black Plates with D Getter construction, the original red RCA screen printing, and the distinctive Bridge Filament configuration, a hallmark of this version. The manufacturing codes identify two specimens produced respectively in October 1964 and May 1968, united by their construction characteristics and selected for their remarkable electrical uniformity.

The measurements carried out with the Amplitrex AT-1000 highlight a particularly interesting match. The transconductance of the four sections ranges between 2500 and 2800 µmhos, with an identical average of 2650 µmhos for both tubes, higher than the nominal reference of 2600. The anode currents range from 8.8 to 10.2 mA, with averages of 9.6 and 9.4 mA respectively, also higher than the 9.0 mA reference. The perfect correspondence of the average transconductances, accompanied by very close anode currents, confirms an accurate matching, while maintaining some differences in the balance of the individual sections.

Both tubes have been subjected to careful instrumental checks that confirmed very strong and stable emission, without fluctuations, short circuits, or gas presence. The checks also revealed low noise and microphonics levels, important characteristics for use in hi-fi equipment and the most sensitive audio stages.

The 6SN7GTB RCA Black Plates find application in hi-fi preamplifiers, headphone amplifiers, driver stages, and compatible audio circuits that do not require absolute symmetry between the sections. RCA production from this period is traditionally appreciated by audiophiles for a musical presentation generally described as full-bodied, natural, and well-defined, with a medium expressive range and a balanced, nuanced reproduction.

The value of this pair lies in the particular Bridge Filament Edition, in the authenticity of the 1960s American RCA production, and above all in the identical average transconductance of the two specimens, accompanied by well-matched anode currents. The well-preserved original screen printings and very good cosmetic conditions complete a particularly desirable set. Two authentic vintage RCA Red Logo tubes, carefully tested and selected, for enthusiasts seeking original American tubes with documented electrical characteristics and distinctive construction.

Condition

  • Condition: Vintage Tubes - Tested and perfectly functioning. Supplied in our custom box for optimal protection.
  • Functionality: Perfectly operational
  • Cosmetic condition: Very Good – Markings clearly legible with slight signs of age. See photos for details.

Manufacturing code:

  • AI → two-letter code → production October 1964 → Radio Corporation of America, Camden, N. J.
  • BZ → two-letter code → production May 1968 → 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.

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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.

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