UltraSonic Rx-9 Tube Damper



UltraSonic Rx Damping Instruments help to bring out the microdynamic speed, linearity, and detail of your source material. Besides reducing microphonic anomalies, Rx allows a freer musical flow, curing a harsh and stealthy "electronics factor" or "dryness" that ultimately ails even some of the most finely honed audio systems. Your tube gear will achieve a fluid, dynamic musical potential like it was engineered to do.

Mildly spring-tempered titanium C-ring holds three modified PTFE isolation pads. Each pad holds a specially formulated polymer O-ring against the tube glass.

Herbie's most popular damping instrument, UltraSonic Rx is appropriate for all audio vacuum tubes, handling radiant heat up to a constant 482° F (250° C). Scroll down for size listings, from smallest to largest.

UltraSonic Rx-Mini

For sub-miniature and Nuvistor tubes approximately 3/8" diameter (9.2mm to 10.4mm), including 5703, 6111, 6112, 6020, 6021, 6088, 6CW4, 6DS4, 6DV4, 6N16B, 7586, 7587, 7895, 8056, 8058, T3 bulb.

UltraSonic Rx-Mini: $26.98 ea.
4 or more: $26.29 ea.

UltraSonic Rx-7

For 7-pin miniature tubes and all tubes approximately 5/8" to 3/4" diameter (16mm to 19mm), including 0A2, 0B2, 0C2, 1S5, 12AE6, 12FK6, 12FM6, 12X4, 304B, 3A5, 3S4, 403A/B, 408A, 5591, 5651, 5654, 5654SQ/W, 6005, 6186, 6AK5, 6AK5W, 6AL5, 6AN4, 6AQ5, 6AQ6, 6AU6, 6BH6, 6C4, 6ER5, 6FG5, 6FQ5A, 6FS5, 6FY5, 6GK5, 6J1, 6J1P, 6J1P-EV, 6J6, 6N4, 6P17, 6X4, 6Z4, 7543, 9001, DCC90, DL92, EC90, EF95, M8100, OA2, OB2, OC2, SBA6. (Most 7-pin miniature tubes, at about 19mm diameter [3/4"], can also use UltraSonic 9.)

UltraSonic Rx-7: $28.66 ea.
4 or more: $27.92 ea.

UltraSonic Rx-9

UltraSonic Rx-9 Tube Damper

Fits miniature 9-pin tubes and all tubes 3/4" to 7/8" diameter (19mm to 22mm), including 10GV8, 12AT7/ECC81, 12AU7/ECC82, 12AV7, 12AX7/ECC83, 12AY7, 12AZ7, 12B4, 12BH7, 12BY7, 12BZ7, 12DW7, 12FQ7, 2C51, 396, 396A, 417, 5670, 5687, 5751, 5755, 5814, 5842, 5879, 5963, 5965, 6072, 6189, 6201, 6267, 6350, 6385, 6414, 6519P, 6688, 6829, 6840, 6922, 6955, 6973, 6AN8, 6BL8, 6BM8/ECL82, 6BQ5/EL84, 6AW8, 6AW8A, 6BQ7, 6BZ7, 6BW4, 6C19P, 6CA4, 6C45, 6CG7, 6CS7, 6DE7, 6DJ8/ECC88, 6E5P/6E5PI, 6EJ7, 6EU7, 6FQ7, 6GC7, 6GF7A, 6GH8(A), 6GU7, 6GW8, 6H23N, 6H30, 6H6PI, 6N1P, 6N2, 6N2P, 6N23P, 6N30, 6N30P, 6N3P, 6N6/6H6PI, 6N6P, 6P1, 6P1P, 6P1P-EV/6II1II-EB, 6S19P, 6S4, 6U8(A), 6V4, 7025, 7044, 7058, 7062, 7119/E182CC, 7189, 7199, 7308, 7788, 7AU7, 7DJ8, 8416, CCa, D3a, E288CC, E80CC, E80F, E88CC, EC86, ECC189, ECC40, ECC802S, ECC803/S, ECC81, ECC82, ECC83, ECC85, ECC86, ECC99, ECF80, EL821, ECL86, EF184, EF86, EL821, EL84, EL86, EM84, EZ80, EZ81, M8162, PCC88, PCL82, PCL86, SV83, (T-6 1/2 bulb).

UltraSonic Rx-9: $28.69 ea.
4 or more: $27.95 ea.

UltraSonic Rx-25

Fits all tubes approximately 1" to 1-1/16" diameter (23mm to 28mm), including metal 12SC7, 5693, "slim" 5Z4, "slim" 6AU4, metal shell 6F6, 6J5, 6R7, metal 6SJ7, "slim" 6SN7, metal 6V6, 6X5.*

UltraSonic Rx-25: $29.15 ea.
4 or more: $28.35 ea.

UltraSonic Rx-30

UltraSonic Rx-30 Tube Damper Fits narrow, straight-sided octal tubes and all tubes approximately 1-1/8" to 1-1/4" diameter (28mm to 32mm), including 0A3A (straight-sided), 1266, 12AX3, 12J5/GT, glass 12SJ7, 12SJ7GT, 12SL7/GT, 12SN7/GT, 3CM, 437A, 4P1L, 5691, 5692, 5852, "slim" 5AR4 (G.E., Sovtek/Reflektor, T-9 bulb), 5Y3, 5Y3GA, 5Y3GT, "wide" 5Z4, 6106, 68HC, 6AH4, 6AU4GT, 6AU4GTA, 6AU5, 6AX4GT, 6AX4GTA, 6AX4GTB, 6BL7, 6C5S, 6CJ3, 6D22S, 6DA4/6DA4A, 6DN7, 6EA7, 6EM6, 6EM7, 6EW7, straight-sided 6F6G, 6FD7, 6FM7, 6FY7, 6H4GT, 6J8P, 6K11, 6L6, 6N8P, 6N9P, 6R7GT (glass T-9 bulb),6SF5-GT (glass tube), 6SH7, glass 6SJ7, 6SJ7GT, "slim" 6SL7, 6SN7, 6SN7GT-series (6SN7GT, 6SN7GTA, 6SN7GTB, 6SN7WGT, 6SN7WGTA), 6V6, 6V6GT (GE, Sylvania, Tung-Sol), 6X5G/GT/WGT, 6Y6, 7355, 7591, 7868, 7N7, C3G, C3M, EC8020, "narrow" EL34 (E-H, Mullard, SED "Winged C," Siemens, Svetlana, Telefunken, NOS Tesla, Tung-Sol), EL34/6CA7 (Svetlana), EL34B (Tung-Sol), GZ30, MT8 bulb, PL504, OA3A (straight-sided), T-9 bulb, VT-231.*
UltraSonic Rx-30: $29.36 ea.
4 or more: $28.59 ea.

UltraSonic Rx-35

Fits standard, straight-sided octals and all tubes approximately 1-5/16" to 1-7/16" diameter (33mm to 36mm), including 5AR4 (Amperex, G.E., Japanese "Mullard" copy, Mullard, JJ, Shuguang), "slim" 6CA7 (Tung-Sol), 6H6, standard 6L6/5881, 6L6B, 6L6GT, 6L6WGB, 6SF5 (metal shell), 6V6GT (RCA), 6V6S (JJ), E34LS, ECC33, medium-diameter EL34 (Amperex, Philips, JJ, some Mullards, Valvo), EL34B (Shuguang), GZ34 (GE, JJ, Mullard, Philips, Raytheon, RCA), KT77.*

UltraSonic Rx-35: $29.74 ea.
4 or more: $28.95 ea.

UltraSonic Rx-40

Fits wide and bottle-shaped octals and all tubes approximately 1-1/2" to 1-5/8" diameter (37mm to 44mm), including 0A3 (bottle-shape), 0C3, 0D3, 1626, 19, 27, 30, 37, 3DG4, 520B (near bottom of tube), 5881, "fat-bottle" 5AR4 (Amperex, Mullard, T-11 bulb), 5AW4, straight-sided 5R4-types, straight-sided 5U4 and 5U4-GB (T-12 bulb), 5V3, 5V4, 5Y3GB, 5Y4GA, 5Z4G, 5Z4P, 6080, "slim" 6550, straight-sided 6AS7, 6BY5/G/GA (straight-sided), 6C6, 6C8G, "Big Bottle" 6CA7 (E-H, GE, Sylvania, etc.), "Black Bottle" 6CA7-Z, 6F8G, 6HB5, bottle-shape 6J5 (ST-12 bulb), 6JN6, 6L6GC (E-H, Mazda, JJ, GE, RCA, Sylvania, Tungsol), 6L6WGC, 6LF6, 6P3P, Sophia Electric "bottle" 6SL7 and 6SN7, 7027/A, 7236, 76, 84, 8417, 85, CV3798, "Fat Bottle" EL34 (Big Bottle), EL509, G75/2D, straight-sided GZ32, "slim bottle" GZ37, KT90, OA3 (bottle-shape), OC3, OD3, PL509, QS150/40, VR105, VR75/30, VR75/40.*

UltraSonic Rx-40: $29.98 ea.
4 or more: $29.19 ea.

UltraSonic Rx-50

UltraSonic Rx-50 Tube Damper

For all tubes approximately 1-3/4" to 2-1/8" diameter (45mm to 54mm), including 10Y, 101F, 1610, 2A3 (Brimar, E-H, E-H Gold, RCA, Sovtek, Sylvania, Tung-Sol), 26, 274B (Western Electric), 307A, 35, 350B, 3A/110A, 3A/110B, 3D21A, 421A, 422A, 45 (RCA, Sylvania, TJ, Tung-Sol), 46 bottle-shape, 572-10, 5998, bulb-shaped 5R4-types, 5R4WGA/B (Tung-Sol), bottle-shape 5U4G, 5V4, 5Y3G (Sylvania), 5Z3, 5Z3P/A, 5Z4G (Brimar), standard and wide 6550 (E-H, GE, Philips, RCA, SED, Svetlana, Sylvania, Tung Sol), 6550A, 6550C, bulb-shape 6AS7, 6B4, 6B4G, 6BY5/G/GA (bottle-shape), 6CA7-Z, 6C33C (upper portion of tube), bulb-shape 6F6G, 6H13, 6H13C, bulb-shape 6L6G, 6N13P, 6Y6G, 71A, 80 bottle-shape, 801/801A, 807, straight-sided 811, 814, C327 ("bulb" 27), CX4, bottle-shaped octals like AZ4, CV181/ECC32, CV181TII (Psvane 6SN7), CV181-Z (Shuguang), CV378 (Mullard), EL156, EL37, bottle-shaped GZ32 (Mullard), GZ33, KT120, KT66, KT88 (E-H, EAT, GEC, Gold Lion/Genalex, JJ/Tesla, SED, Shuguang, Sovtek, Svetlana), PX4, ST-14 bulb, ST-16 bulb, U52.*

UltraSonic Rx-50: $30.29 ea.
4 or more: $29.49 ea.

UltraSonic Rx-55

For jumbo-size tubes 2-3/16" to 2-5/16" diameter (55mm to 59mm), including 101D/101F, narrow 211 (RCA), 211/VT-4C (GE), 2A3 (EML), 2A3-Mesh (EML), 274A, 300B "Balloon" (KR), Svetlana 300B, Takatsuki TA-300B, 45 (EML), 46 globe-shape, large bottle 5Y3GB (smaller Mazda uses UltraSonic 40), 80 globe-shape, "narrow" 805 (RCA, United), 829B, 841, 842, narrow 845 (Amperex, RCA), 845A (Shuguang), 872, GE211, "Big Bottle" GZ37, KT150 (specify size "60" in comments section of order form), SV811-10, ST-17 bulb, T-18 bulb.*

UltraSonic Rx-55: $31.89 ea.
4 or more: $30.99 ea.

UltraSonic Rx-65

With plenty of flex to accomodate a wide range of tube diameters, fits giant tubes from 2-3/8" to 3" diameter (60mm to 76mm), including 101D "tennis ball," 101J, 102B, wide 211 (Sophia, TJ), 274B (EML, Shuguang, Sophia, Valve Art), 2A3-40W (JJ), 2A3 Meshplate (Sophia, TJ), 2A3 Globe Meshplate (Sophia, TJ), 2A3C (Shuguang), 300B (AVVT, E-H, EML, JJ/Tesla, Sovtek, KR, TJ/Full Music, Western Electric), 300B-XLS (EML, KR), Meshplate 300B (EML, Golden Dragon, TJ, Sophia, Shuguang, Valve Art), 300B Globe Meshplate (Sophia, TJ), 32B, Globe 45 (TJ/Full Music/Sophia), 45C, 45N, EML 45-mesh, 50, 520B, EML 5U4G-Mesh & 5Z3-Mesh, 6C33C (wide portion of tube), 803, "wide" 805 (Amperex, Shuguang, TJ), 811A, 813, wide 845 (Sophia, Shuguang metal plate, TJ), 845B (Shuguang), F2A, GM70, PX25, ST-18 bulb, ST-19 bulb, T-20 bulb.*

UltraSonic Rx-65: $32.85 ea.
4 or more: $31.95 ea.

UltraSonic Rx-100

With extra-heavy-gauge stainless steel C-ring and four isolation pads, UltraSonic 100 thoroughly tames microphonics in super-giant tubes 3-1/2" to 4-5/8" diameter (89mm to 118mm), including 833, KR T-1610 (Kronzilla), and tubes using T-36 bulb.

UltraSonic Rx-100: $40.49 ea.
4 or more: $39.89 ea.


Tube diameters and shapes sometimes vary. To estimate your tube diameter, just place a wooden or metal ruler against the side of your tube and "eyeball" the size – if you align your sight in a straight line to one edge of the tube and then in a straight line to the opposite edge, the measured difference in-between will be very close to the tube's actual diameter. Or measure the circumference and divide by pi (3.14).

For tubes that fall in-between UltraSonic sizes, smaller size is the default recommendation (though either size will work). Tube size data indicates "maximum" tube diameter; tubes are often a little smaller than indicated. Titanium C-rings have some flex to them to accommodate variation in bulb diameters and can be bent to somewhat smaller or larger sizes.

Additional information, including bulb sizes, on most tube types and brands can be found here:

[ Frank's Electron Tube Data Sheets ]

inches millimeters 

Changing gear? UltraSonic Rx isolation pads can be slid off one titanium C-ring and onto another. If you need a different size than what you have, spare C-rings are available, so you don't have to buy a whole damping instrument to change sizes. Isolation pads are interchangeable among standard sizes (UltraSonic Rx-Mini thru 50), and amongst heavy-gauge sizes (UltraSonic Rx-55 thru 100). UltraSonic Rx isolation pads achieve a full upgrade to "Rx" for standard UltraSonic Damping Instruments.

 Titanium C-Ring Only (no pads) 
UltraSonic Rx sizes Mini thru 65
$3.95 to $9.98 ea.
(4 or more, one size: 10% off)

UltraSonic Rx Isolation Pad

$7.95 ea.
(12 or more: $7.49 ea.)

90-day no-risk trial. If not satisfied, simply return any item within 90 days for a complete refund of the purchase price.

Lifetime warranty. If anything ever goes wrong, simply return any Damping Instrument to Herbie's Audio Lab and it will be repaired or replaced and returned to you at no cost.

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