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HAL-O III Stabilizer - Herbie's Audio Lab
HAL-O III Stabilizer - Herbie's Audio Lab
HAL-O III Stabilizer - Herbie's Audio Lab

HAL-O III Stabilizer

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From $46.15
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HAL-O III brings out the best potential in extremely hot-running audio rectifier, power tubes and other sensitive vacuum tubes. HAL‑O III subdues heater-generated vibrations and common microphonics, allowing a truer rectified current and truer amplified signal. A less-fuzzy, cleaner rectified current will typically cause other audio tubes in a component to render the music more clearly. Tube output will be more musical, more energetic and less vague, while maintaining your system's unique nature and character.

With spring-tempered titanium C-ring and annealed titanium isolation pads, HAL‑O III is appropriate for all vacuum tubes, ideal for extremely hot-running tubes, able to handle continuous tube heat in excess of 1000° F (538° C).

HAL-O III-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 size 9.)

HAL-O III-9: Fits miniature 9-pin tubes and all tubes 3/4" to 7/8" diameter (19mm to 22mm), including 10GV8, 12AT7/ECC81, 12AU7/ECC82, 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, 6900, 6922, 6955, 6973, 6AN8, 6BL8, 6BM8/ECL82, 6BQ5/EL84, 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, 6N2P, 6N30, 6N30P, 6N3P, 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, ECC802S, ECC803/S, ECC81, ECC82, ECC83, ECC85, ECC86, ECC99, ECF80, ECL86, EF184, EF800, EF86, EL821, EL84, EL86, EM84, EZ80, EZ81, M8162, PCC88, PCL82, PCL86, SV83(T-6 1/2 bulb).

HAL-O III-25: Fits all tubes approximately 1" to 1-1/16" diameter (23mm to 28mm), including metal 12SC7, metal 12SJ7, 5693, "slim" 5Z4, "slim" 6AU4, metal shell 6F6, 6J5, 6R7, metal 6SC7, metal 6SJ7, "slim" 6SN7, metal 6V6, 6X5.*

HAL-O III-30: 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, 6FY7, 6H4GT, 6J8P, 6K11, "slim" 6L6, 6N8P, 6N9P, 6R7GT (glass T-9 bulb), 6SF5-GT (glass tube), 6FM7, 6SC7 (glass tube), 6SH7, glass 6SJ7, 6SJ7GT, 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, OA3A (straight-sided), PL504, T-9 bulb, VT-231.*

HAL-O III-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.*

HAL-O III-40: Fits wide and bottle-shaped octals and all tubes approximately 1-1/2" to 1-5/8" diameter (37mm to 44mm), including 0A3 (bulb-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" or Fat Bottle 6CA7 (E-H, Sylvania, GE, 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 (bulb-shape), OC3, OD3, PL509, QS150/40, QS75/40, VR105, VR75/40.*

HAL-O III-50: 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, 6AS7G, 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 bulbST-16 bulb, U52.*

HAL-O III-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 size 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.*

HAL-O III-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 bulbT-20 bulb.*

HAL-O III-100: With extra-heavy-gauge stainless steel C-ring and pure titanium isolation pads, HAL-O III-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.

Customer Reviews
4.9 Based on 18 Reviews
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Clayton C.
United States United States
Halo-65 dampers

Recently purchased another pair of Herbie’s Tube Dampers for a new pair of 300B’s. I’ve used them on all my tubes for years. An excellent product. They are an obvious sonic improvement on every tube I’ve used them on, and I use them on all the tubes in my system.

Herbie's Audio Lab HAL-O III Stabilizer ReviewHerbie's Audio Lab HAL-O III Stabilizer Review
Thomas G.
United States United States
HAL-O III tube stabilizers: Great product and quick delivery

Installed five of the HAL-O III stabilizers in my Audio Note Meishu Tonmeister in two sessions. I saved the two AN4300 tubes for last, and this had the most significant affect. Clearer vocals, improved tonal clarity and focus. Helped reveal a significant difference in two good dacs that had previously sounded very much the same. I would recommend these.

Ricky W.
United States United States
Nothing to lose.

To the point. It works. I didn't expect much and I knew I could return them if I heard no difference. Unlike components and other items, there is no break in required for these. The difference was immediate and obvious. Much clearer sound.

James A.
Australia Australia
Lowers the noise floor on my power amp.

The Herbie’s HAL-O III stabilisers on the driver tubes and 50% of the power tubes in my SAP Anniversary OTL cleaned up the soundstage and lowered the noise floor, giving my special power amplifier an added X factor in my revealing system. Surprised and totally delighted with the result.

Thomas H.
United States United States
Hal o lll

On my first listen I noticed everything was more THERE....more refined and more clear....voices was much more focused and it wasn't a small difference....i also actually forgot I installed them since I was doin a makeover and cleaning job...also rearranging took me about 4 hrs to clear everything out and then put back into place....i had marked my speakers so to put them back in the same spot....well when I finally settled down I turned the system on to play some diana krall while I put everything back after about 30 min of playing music I finally was relaxed enough to sit down and listen to maybe tweak a speaker in and out of forward or back a bit but when I sat down to listen I was in shock....i was thinking damn this thing sound better than ever but didn't know why, then it hit me....omg could this be these Hal o lll tube I started to listen serious and was just first I couldn't explain it then I remembered....I have to say so far this is the best tweak I ever had....better than any power cable or speaker/interconnect.....truly shocked and amazed..!!

Martin J.
Australia Australia
Superb product and Customer Service

My story will focus on Herbie's excellent Customer Service, rather than the quality of the product (the other reviews highlight this already, plus I'm back for more, which speaks for itself). I previously used other tube dampers from Herbie's, the rubber parts of the dampers perished over the years and so I emailed to ask what could be done about it (I wanted to move up to the HAL-O III). Long story short, they let me use my lifetime warranty to move up to this model, minus the cost of my original purchase. Oh yes, I also needed one of the three rings to be made to a custom size (due to tight spacing in my DAC), so they did this free of charge for me. Always a pleasure to deal with and the dampers sound superb - thanks guys!

William V.
United States United States
Buy Herbie's tube dampers now

I have heard and read many positive reviews on Herbie's dampers over the years but never thought they would make a large improvement over the manufacture provided rings. I was way wrong. These made a huge improvement in SQ and are well worth the price. Per my title buy them now!

Poland Poland
They work!

I was skeptical before ordering as I was afraid the dampers would make the sounder cleaner but perhaps also more technical, no as smooth as what you expect a tube amp to sound like.. Nothing of the kind, the sound did not lose any of the smooth tuby character. However, the biggest surprise for me what a huge improvement in soundstage. These babies are expensive but well worth the money. On the downside, I'm not impressed by customer service - I wrote twice, no response (I used the form, perhaps I should have just copied the email address).

Anthony S.
United States United States

placement is critical there good for new tubes not N.O.S. but in the right spot they work great better focus better imaging better depth a+

Kristofer S.
Sweden Sweden

I ordered two tube dampers for my amplifier an ARC 75 SE. I put these tube dampers on the 6H30 tubes. I can only say wow what a difference it made. The sound picture got bigger, it was as if a film was lifted away from the speaker. The base became much tighter and with more texture. But where these tube dampers really perform amazingly is the ability to bring sound to life. Just as if everything comes alive and the treble becomes more relaxed and more accurate without being intrusive.

Andrew Y.
United States United States
Arc Ref 6 Huge sound improvement!

Huge difference using this on the rectifier 6550 tungsol tube in my arc Ref 6. Placed on the widest part of the tube. Improved bass and seperation. Also used on the input tube.

Halos are a game changer!

Felix Audio Euforia Tube headphone Amp:, the Halos reallly opened up the tubes, (vintage NOS Tung Sol 7236 Dual Power Triode Amplifier Tube from SAGE Mainframe Computer and 1955 CBS Hytron 6sn7gt black plate tubes) on my already fantastic Felix Audio Euforia! Without your Halos...sound was flat and lack depth and bass was thin...when I added the Halos...the tubes jumped up to a heavenly level of pure tonal balance and depth! It is just amazing how the Halos allow the electrons to be free to fly..without any glass envelope to restrict or add vibrations...the glass envelope just disappears! I will never remove the Halos..or the tenderfeet!