Handmades

TUBE VARIABILITY – THE MOST VARIABLE COMPONENT IN YOUR AMPLIFIER
A vacuum tube is very complex. It looks to be a very simple device, but is anything but simple. In your amp, you may have +/- 20% resistors, and other items of wide tolerances, but vacuum tubes can, and will vary, much more.
A typical preamp tube such as the common 12AX7 / ECC83 / 7025 will have many construction variations. There are long plates, smooth plates, box plates, rib plates …. Long and short cathodes, differences in construction. These aspects, and many more, lend to changes in tone and response. Even tubes of the SAME MAKE, SAME TYPE, and SAME MAKER from the same batch, will vary widely.
A typical 12AX7R2 as made in the Reflector Factory and distributed under the Sovtek name, will have Transconductance ranging from 900 to 2000, as one example. The target spec is 1600, As you can see from some simple math, this is WAY outside of the +/- 20% range of your resistors or other components. Output in milliamps, expected to be 1.2 milliamps at 250 plate volts and –1.2 volt bias, in these tubes shows 0.6mA to 1.6mA. The average is about 0.8 (about 30% less than expectation spec by the way). Gain (not the same as output), and plate resistance also vary widely. This is one reason that when you retube your amp with fresh and new tubes, at times you may find, the amp has lost it’s life. Why? Your old V1 may have been putting out 0.9 milliamps in current … your new tube has 0.6 milliamps, 30% less current output than your “old” tube. What can you do about this? Your best option is to use a tube vendor that tests ALL preamp tubes for things like low output, low noise, and lack of microphonics. Many rely on just sending all their tubes out to the customers, relying on a warranty to take care of the testing for them. In most cases, it is not worth the trouble for the customer to send back one single tube, box, ship, and the post office line …they just forget it.
Why are tubes so variable? First off, there is a LOT of hand assembly. This is not like making silicon devices on AMD or INTEL production equipment. There are also a LOT of materials, and the ratio of many of these materials is very critical. Change a plate material or cathode coating, and you may have changes. Move things around in production and you will have changes. There are many aspects that can change tubes, even the weather during production. These little glass bottles are generally not made in a silicon clean room environment.
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What sorts of materials can change? How can it be complicated … some metal and glass? Sure, we know that metallurgy is an exact science, and when it comes to airplanes or high tech items, this is paramount. But, in vacuum tubes, it generally does not share the same attention – one more variable.
The tubes use a number of materials. Some of them are mish metal, nigrosine, porcelain, petroleum jelly, zinc, calcium aluminium flouride, resin (synthetic), ethyl alcohol, lead acetate, malachite green, glycerine, zinc chloride, iron, marble dust, wood fiber, strontium nitrate, lead oxide, zinc oxide, lava, mica, tin, sodium carbonate, sodium nitrate, silver oxide, barium carbonate, calcium carbonate, arsenic trioxide, ammonium chloride, strontium carbonate, potassium carbonate, isolanlite, bakelite, molybdenum, phosphorus, alumina, silicon, borax, shellac, tungsten, barium, copper, titanium, carbon, silica, glass, chromium, magnesia, clacium, platinum, caesium, cobalt, strontium, iridium, magnesium, monel, rosin, nickle, calcium oxide, cobalt oxide, barium nitrate, thorium nitrate. Actually a somewhat complex recipe!
After all these ingredients are “mixed”, we still have all the variability of assembly and manufacture. Remember when I said that a lot of this is done by hand? Even the machine aspects are pretty tight in the tolerance department, so the machines must be kept within close tolerances, which is not always the case due to wear or lack of attention to maintenance.
How close are these tolerances? Lets look at some of them in a typical output tube where there is more room to work than in a preamp tube, so this is “easy”.
Grids – the diameter of the grid has to be 0.001 inch. Cathode sleeve wall – 0.002 inches thick. Air pressure – 1/100,000,000th of sea level.
The glass bulb – inspected under polarized light for stains. The Plate – diameter gauged to 0.002 inches. Cathode coating – weight variation less than 0.0007 ounce.
Grid wire – diameter cannot vary more than 0.00009 inch. Heater wire – diameter cannot vary more than 00002 inch.
So, now we have the basic “parts” from the most easily recognized major aspects of a tube, yet we still are looking at putting it all together, welding or attaching it all somehow, and expecting it all to not only work, but work in an expected manner. It is pretty amazing, that today, these things even work at all!

Olá BetoKnigth

Este link que você postou é ......

Abraços

Eduardo

A Electro Harmonix é uma outra opção da New Sensor para uma marca honesta. Sai da mesma fábrica que as Sovtek, mas o desenho é diferente.

RUSSIA

Reflector Corp, Saratov

Makes most of the tubes marketed by New Sensor Co. of New York under the "Sovtek" brand name. Some of these are old
Russian types, others are made especially for export. Types in production: 2A3, 300B, 12AX7 (3 variations known), EL34 (3
versions), 6CA7 fat, 5AR4, 5881, 6922, 6EU7, 6L6GB, 6V6GT, 6072A, 6973, 7199, 7591, 7868, EL84 (2 versions), KT66, KT88, KT90,
6P15P. "Sovtek" also markets 5U4G, 5Y3GT, 6SN7, 6SL7, three 12AX7s and a few other types made at other factories. Note:
there is no "Sovtek" factory. "Sovtek" is only an American brand name owned by New Sensor. New Sensor now owns the
Svetlana brand name and is using on tubes manufactured by Reflector.  The Electro Harmonix tube are also made by this
plant.  In 2005 New Sensor bought the names of Mullard and Tung-Sol and are placing these names on tubes of their New
Sensor banner.

Ryazan Plant of Electronics, Ryazan

Makes power triodes for RF and audio applications. Some are sold outside Russia by Svetlana Electron Devices. Ryazan has
also made large thyratrons and pulse tubes. Types in production: 811A (popular and sold all over the world), 812A, SV811-3,
SV811-10, SV572-3, SV572-10, SV572-30, SV572-160, GM-100, others. SV types and 812A are made especially for Svetlana
Electron Devices.

SED Winged C, St. Petersburg

A major Russian power-tube manufacturer. Formerly a part of the huge Svetlana collective factory, now independent. SED
tubes are now distributed in North America and Europe by PM Components. Types in production: EL34, SV6L6GC, SV6550C,
300B, EL509, EF86, 6BM8, 6AS7, 3CX300A1, 6D22S, GP-5, and a long list of large power types for amateur radio, broadcast and
industrial uses. KT88 and 12AX7 are have been recently introduced.

Ulyanov, Ulyanovsk

Large state-owned factory specializes in military equipment. Also makes tubes for use in military aircraft electronics. Types in
production: GU-50, GU-13/813, 6S33S-V, 6S19P, 6S41P, others. 6S33 is becoming popular in high-end amplifiers in America and
Japan.

Voskhod, Kaluga

Large collective factory, makes many ICs and other semiconductors as well as receiving tubes. Types in production: 6N1P-EV,
6AX7, 12AX7WA and WB, 6SN7, 6SL7 and a few other types sold by various firms outside Russia, such as New Sensor/"Sovtek"
and Svetlana Electron Devices.

CHINA

Shuguang Electrical Factory No. 1

Owned by Korean firm Samsung. Shuguang makes most of the popular audio and guitar types, which are frequently rebranded
by importers and OEMs. Types believed in production: 6L6GC, EL34 (3 types), 6550, KT100, 5AR4, 2A3, 807. Possibly 211,
845--unconfirmed. Shuguang's low-cost tubes are often seen in guitar amps. (Thanks to Chris Beeching for info.)

Liuzhou

Makes many types which are marketed abroad. PM Components, a British firm, has "Golden Dragon" types made by Liuzhou.
(Thanks to Chris Beeching for info.)

O&J Enterprises/Valve Art

Makes the following: 6L6GC, EL34, 6550A, KT88, KT100, 300B, 300B-C60 (graphite plate 60w), 5300B (graphite plate 80w
150mA), and 6300B (graphite plate 80w 180mA), plus possibly other types, at a factory in Changsha, Hunan. (Thanks to Wilfred
ter Borg for type list.)

"Sino" factory in Beijing recently stopped making 12AX7, 12AT7, 12AU7, 6GH8, 6AN8 and other small tubes, due to a poor
market and tough competition from Sovtek/New Sensor. It is said that Sino made the popular, low-cost 211s and 845s often
seen in SE amplifiers; this cannot be confirmed. Sino is apparently no longer making any tubes. There are other tube factories
in China. Most keep a very low profile. Some of these lesser-known factories specialize in transmitting tubes such as the 811A,
812A, 813, 3-500Z,4-400, 100TH, 833 and others. Such transmitting types are often branded with old American/European brands
and sold without notification that they are Chinese-made, as are the audio types.

SLOVAKIA, CZECH REPUBLICS

JJ Electronic, Cadca, Slovakia

A spinoff from now-defunct state factory Tesla factory. Outside of Slovakia, JJ tubes are often sold under the Teslovak or Tesla
brandname. Groove tubes is a major distributor. Types in production: GZ34, KT88S, EL34, E34L, ECC803S, ECC83/12AX7, EL84,
2A3, 6L6GC, 6V6GTS, 300B, 7027A, 7591S. Some of the power pentode types are available in red or blue glass.

AVVT, Prague, Czech Republic

Run by former Vaic Valve Co. founder Alesa Vaic. Manufatures audio power triodes for high-end hi-fi amplifiers. Types in
production: AV300B SL, AV32B SL, AV62B SL, and others.

KR Enterprise, Prague, Czech Republic

Formerly Vaic Valve Co, now operated by Riccardo and Eunice Kron. Manufactures power triodes for high-end audio
amplifiers. Types in production: VV30B, VV300B, VV52B, KR1, a single-plate 2A3 and other types..

YUGOSLAVIA

EI Electronic Industries, Nis, Serbia

Former state-owned factory, makes all types of electrical products, still making tubes using some old Philips production
tooling and equipment. Marketed outside of Serbia by Edicron Electronic Components Ltd, UK. Types in production: 6CA7,
6CG7, 12AT7, 12AX7, 12BH7, 12DW7, EL34, EL519, PL519, KT90, KT99, EL84, EL86, possibly a few others. Latest reports indicate
that the EI factory was not destroyed in the 1999 Kosovo conflict by NATO missles.

UKRAINE

Poljaron, Lvov

Makes 833A and some Russian power types, plus related products such as vacuum capacitors.

USA

Richardson Electronics, LaFox, IL

Makes a 300B, 845 and 50 sold under the Cetron brand for high-end audio, as well as a KT88 sold under the National brand.
Richardson has large quantities of tooling obtained from old American tube factories when they shut down. Also makes some
larger transmitting and high-voltage types. Richardson markets many tubes, obtained from other factories worldwide, under
their own brandnames; such as Cetron, National and Amperex.



Westrex Corporation, Kansas City, MO

Makes the reissued Western Electric 300B for high-end audio. Claims to be developing a KT88, WE308, WE274A and other old
WE types for future manufacture. Corporate and sales offices are located in Atlanta and Chattanooga. Also has sales office
in UK. Tube manufacturing facility was relocated from Kansas City to Huntsville, AL. This firm is independent of AT&T
Corporation and has licensed the brandnames from AT&T.



MU, Oceanside, CA

Small contract factory, makes occasional runs of unusual glass and metal-ceramic tubes for military use. Still makes some of
the old "Bendix Red Bank" tubes, such as the 6094 and 6384, in occasional lots.



Triton Services ETD, Gaithersburg, MD

Makes some Eimac and Litton glass power types, using equipment from the original manufacturers. Recently discontinued
some glass types, such as 4-65A, 4-125A, 250TH, 304TH/TL, etc. (these types are now only available from China).

desculpe, fiquei confuso pois voce tinha mencionado que saia da mesma fabrica da sovtek...

Da antiga fábrica de válvulas da Tesla na Eslováquia.
https://www.eurotubes.com/eurotubes-JJ-Electronic-vacuum-tube-factory-tour.htm

Fazia parte da Tesla antes da privatização.
A Tesla que era a estatal Soviética, foi dividida em várias partes.

....
Então, não entendo porque essa falta de corpo no som. Seria esse um som "vintage" ou essas Mullard que comprei são falsificadas?

Comparando-as com válvulas Sovtek e Tungsol, as Mullard, apesar de terem as placas maiores, são as que tem o menor ganho.
No link abaixo, nota-se que a Mullard (última a direita) tem a placa bem maior que a Sovtek e a Tungsol:

Eu entendo que pode ser uma tapeação, mas, no caso, não se trata de válvulas iguais, uma vez que a placa dessas Mullard é maior que as da Sovtek e Tungsol. Daí a minha dúvida.

O que eu acho estranho é que se as Mullard que eu comprei tem a placa grande, ela deveria receber, pelo menos, uma designação de "LPS", o que não acontece.

A "Reissue" que você vende na Altana parece ter a placa menor e, então me explique qual a diferença entre essa válvula Mullard tosca que eu comprei e a sua?
Afinal, ambas não são feitas na Reflector?

Tem muitas outras fábricas no mundo que não são tão conhecidas, e que produzem com muito mais cuidado que qualquer New Sensor da vida.
A pouco tempo eu descobri as TJ,  uma válvula handmade na essência.
http://www.diyhifisupply.com/opcart/index.php?route=product/manufacturer/product&manufacturer_id=13

Eu tenho uma 12AX7 dela aqui e por coincidência ou não, elas piscam iguais as antigas mullards e telefunkens.
Iguais a desse cara aqui:
http://www.youtube.com/watch?v=uYXjAOW61-g