Sovtek is a brand, not a factory. Either these are Russian NOS tubes, simply rebranded, or they are new made tubes from the REFLECTOR FACTORY in the Ukraine, Russia.

REFEECTOR tubes are sold under a range of brands, but in the end it is all from one factory. Brands seen to far are: New made Tung-Sol, Mullard, Electro Harmonix, Svetlana S-Logo and Gold Lion. So when buying a SOVTEK you get either a NOS tube, or a REFLECTOR tube. The NOS are often from old Reflector stock, but not always. Most of the new production Sovteks are a tube of it's own, and are not available at other brands.

The greatest amp companies in the world use SOVTEK Tubes:

Fender® • Marshall® • Peavey • Crate • Mesa Boogie • Atma-Sphere • Ampeg • Soldano • Hark• Laney • Retrospec • Carlsboro • Sound Vasin • Victor • Solo • Koch • Wytech • Triode • Bogner • Melos • Audio Note • Pal • Penn • Atd • Blue Circle • Precision Power • Cary • Audio Professor • Brunetti • Vulcan • Blues Land • Antique Sound Lab • Victoria • Balanced • Behringer • Hi-Mu • Velleman • Dynaco • Matamp • Ebs • Matchless • Budda • Orange • Simetel • Chimera • Kitty Hawk • Bradley • Aguilar • Audio Research • ATD • Tophat • Requisitte Audio • Alessandro • Rogue Audio • Torres • Musica Nova • Sherlock • Cosmos • Chelmer • Reflextron • Convergent • Sonic Frontiers • Kora • Graaf • Manley Labs • Randall • Holland • Tone King • Real Tube • Dr. Z • Carvin • SLM • Marble • L'Aurora Sound • Viva • Ashdown • Synthesis • Torres • KJL • Komet • Unison • Muse • Pathos • Esh • Audio Note • Kell • Matamp • Kendrick • Bruno • Dutch • Engl • Demeter • Eden • VHT • Vtl • Rocktron • Uncle Albert • Diaz • Stevens • Wells • Fi • Hoffman • Demeter • Wellborne • Rivera • Standel • Sovtek


What means the letters PL

The Sovtek KT66 has a different construction from the vintage KT66 as made by G.E.C.   The Sovteks are related to the American 6L6.  The Sovtek tube has a fully  machine made glass construction,  The Chinese and G.E.C. tubes have  a handmade glass construction. 

The Sovtek low-resonance glass shape gives this tube a unique appearance. 


Out of production, 5 pairs left on stock!


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ATTENTION: The more expensive Electro Harmonix "Gold" Version is sold out. The SOVTEK is an ideal replacement. Personally I think the Sovtek is even a MUCH better tube as the Electro Harmonix was suffering from vacuum often. My expectation is, the SOVTEK are probably NOS anyway, since I had lots with 1972 datacodes before, what else shall I say.

The 6C45 tube

A most amazing tube from the days of the cold war. This is a frame grid tube, meaning the grid wires are so extreme thin, you cannot see them with the eye. If you remove the grid from a broken tube, it looks like a light absorbing, transparent foil. (same effect as sunglasses). This is how thin the grid wires are. You can't see them, but still they absorb some light of course. For making a grid like this, first a frame is made of hard metal. Around this frame, the grid is wound, and then frame and grid together go inside the tube. Like this, very precise tubes of high gain can be constructed. I really want to put upfront this most amazing technology.

Characteristic for frame grid tubes is the nice uniformity of transconductance. The 6C45 has a gain of 50x and it has enough plate dissipation to build a small SE output stage with it. Originally this tube was not made for SE stages, but it's a secret tip and it works very nice.

The problem with this tube:

This is a difficult to make tube, since parameters are combined in this tube that bite each other. Meaning, when you still do so, uniformity of production data will not be achieved. Yet it is an amazing tube, but you have to accept the large spread of bias data, and transconductance, which results in different gain of the amplifier stage. When selecting, we see basically high Gm tubes have a lower bias current and vice versa. This is nothing bad, but it simply the anode distance is variable. Then, by looking at the tube construction, we already see what causes this, the anode fine adjustment as with ECC88 is not possible here. So this is something NORMAL we have here, and no quality issue. It is just, the only way to deal with this, is parametric selection both for Gm and Bias DC current at the same time.

It can make you really unhappy, when most sellers ship any tube whatsoever. Also the ones that I think are questionable. For this reason, we recommend to buy only the selected versions that we sell, tested with the AMPLITREX computer tester. Another problem these tubes can have, is vacuum defects, but this is a general problem with all Electro Harmonix 9 pin tubes. Specially for 6C45 which gets extremely hot, the smallest sign of something not 100% with the vacuum, is a reason to reject the tube. The practical situation proves we are right by this. If you store such tubes which are initially "ok" but perhaps the vacuum not exactly perfect, then after some years you find them on the shelf with a white getter, and all vacuum lost. So the ones we sell, are selected for perfect vacuum, and high transconductance. Actually this process we have, seems to reject the weak ones very good.

So we do not want you to be afraid of this tube, but you should be afraid of 6C45 that you buy from any random sellers in the internet, which only want to sell by price, and not by quality. That doesn't pay off with 6C45.

Select the right transformer:

This tube is ideal for use with Lundahl LL1660 driver transformers. You can wire the transformer for instance in a 4.5 : 1 step down scheme. This will still leave you with a total gain of 50/4.5= 11x which is a good number. The good part is now, the output impedance of this tube is reduced with a factor (4.5)² = 20. So the original Ri of the tube, of apr. 1100 Ohms will appear as 55 Ohms (!) at the output of the LL1660. This 55 Ohms is very nice for head phone amplifiers, or pre-amp outputs. So a line output stage with this tube, using the LL1660/25 would have these specifications:

Design example for line output stage:

This tube is ideal for use with Lundahl LL1660 driver transformers. You can wire the transformer for instance in a 4.5 : 1 step down scheme. This will still leave you with a total gain of 50/4.5= 11x which is a good number. The good part is now, the output impedance of this tube is reduced with a factor (4.5)² = 20. So the original Ri of the tube, of apr. 1100 Ohms will appear as 55 Ohms (!) at the output of the LL1660. This 55 Ohms is very nice for head phone amplifiers, or pre-amp outputs. So a line output stage with this tube, using the LL1660/25 would have these specifications.

Transformer LL1660/25 with connection scheme: Alt Q (see this website for Lundahl transformers)

  • Stage Gain = 11x
  • Output impedance 55 Ohms
  • Frequency range 10Hz...35kHz at 1db

Note, when designing with LL1660: First let's say here the normal LL1660/25 works very nice. For superior noise isolation with line driver amps, or for user increased safety with head-phone applications, the "S" version (shielded) can be used. The shield is in between primary and secondary and must be grounded. Both the standard or the "S" version are available with amorphous core.

datasheet of LL1660


This tube is probably the last great double triode the Russians made. For a long time is was forbidden by the military to sell NOS stock of this tube. They had blocked all stock, and kept it "secret". About 9 years ago, stocks were released bit by bit. Indeed this tube is really magic in performance. You need to read the datasheet (at the "Techcorner" from this website menu!). Then you will understand why the military wanted to keep this for themselves. This tubes has all you expect, and all good things combined. So you have quite high dissipation, high gain, amazingly low plate impedance, as low as you get normally with a 2A3 or so. This incredible low plate impedance was NEVER presented before in a miniature, NOVAL based tube. And it never was made later on, by any manufacturer. Only THIS tube had that. The plates of this tube are not by thin "plate". They are solid block nickel, that is where the amazing electrical properties come from. This tubes is a miniature tank, and yet with beautiful HiFi data. And then you get two of those rubies in one bulb. Note they have made the glass extra long because of the huge getter. That will give extra long life. What else do you want? Gold pins may be.. But that exists also, then you take the EHX Version, the EHX is available also balanced, meaning both triodes are identical.

datasheet: Page1 - Page2 - Page3 - Page4

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6SL7-GT / 6SN7-GT

These are NOS tubes, re marketed by Sovtek.  They feature the GT option, which means higher power per system.  These have the older, inner  glass construction which at those days was hand-made!

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12AX7WA / 7025

The Sovtek 12AX7WA is said to be from Russian Military stock. This is probably the only tube of this kind that is available just normally. It has is beautiful black boxed plates. Construction and mechanical quality are absolutely outstanding, so this is the tube of choice by several Japanese amplifier companies at the moment. The boxed construction gives it the appearance oft the famous -holy grail- Telefunken ECC803S.

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The Sovtek 12AX7-LP is a tube from new production. On Par with many historical European ECC83 tubes.

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The Sovtek 12AX7-LPS is a close copy of the Telefunken 12AX7 (ECC83), featuring the spiral heaters. This makes is very suited for low hum applications.

Click in the images to see the details. You can see the ribbed plates, dimensions are the same, also the double mica in the top. Function is this is, to tighten cathode better, and reduce microphonics.


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The Sovtek EL84 is "the" tube when you are looking for a plain strong EL84 at reasonable cost

What means the letters PL

Factory matched version of EL84

What means the letters PL

This is a specialty. As you perhaps know, Sovtek tubes can be new production or rebranded NOS Russian military tubes. This seems to be the case with the "M" version here. There used to be a so called "EB" version, originally from Russia, which is longer life and tighter specified. These are fully impossible to get now. However, under the Sovtek brand these are still available, and are called "M" version.

OB2 105Volt reference tube

Though it can be seen (and used) as a small version of OC3, it is not the same.  The OB2 is a voltage reference or regulator, whereas OC 3 is a regulator tube only. A reference tube will give amazing voltage stability at exactly the current it needs for that. Get the right value from the datasheet, but it is around 10mA. Alternatively you can use it as a small regulator tube as well (Same principle as a Zener diode).

A reference tube will outdo a Zener diode by far! Zener diodes have a MAJAR problem, and that is temperate dependence is terrible. They have higher noise, and even the high voltage Zener diodes are not very reliable. So a complete circuit with some power electronics may fail, just because the Zener diode breaks down. So even today a gas reference tube is the best you can buy. It was know well in industry, and in many equipment from the past you find OB2, wheras solid state devices would have been available as well at that time. Click here for a compare between a Solid State Zener diodes,  and the "old" equivalent  OC3.    Also here is a nice article about gas reference tubes

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OC3 - VR105 / 105Volt /40mA regulator tube
This  is a regulator tube,  no reference tube.  The OC3 regulator tube is optimized for not changing the voltage over a wide range of current. When you go above the specified maximum current, this is even possible, when you do not expect the perfect regulation from it, that you have below 40mA. One of the best voltage regulators ever made - and still available.  50x more stabile than a Zener diode.  Gas filled tube, without filaments.   Has just two connections,  and is used like a Zener diode.  Can be used as transient suppressor, or stabilizer device.  Can be serialized to get the required voltage.  Just put four in series and get 420 Volt / 40mA. The American types are lighting pink.  The Russian types  use Neon gas, and lights up bright orange. Click here for a detailed image.    Click here for a compare between a Solid State 120V Zener diodes,  and the "old" equivalent   OC3.    Nice article about gas tubes