6L6 Family Tubes comparison 6L6 타입 진공관 비교


The main differences 차이점


6L6GC:

This is the newer version of this family of tubes, made to meet the demands of public address and musical instrument amps, and high fidelity equipment.
It's a true heavyweight, with 500 volt at 30 watt plate ratings, and 450 volt at 5 watt screen specs! This tube will replace virtually any of the other 6L6 tube types.
These are found in straight sided glass packages, and most are no older than the late 1950s as this tube has not been around all that long.
This is the only type being currently made today, but caution is advised if your amp puts nearly the max voltage on plate or screen as some of the modern tubes may arc over.
You may find that only NOS versions will work in your amp. The most desirable of these tubes is probably the RCA blackplate, which was only produced until the later 1960s,
however other NOS greyplate USA made versions are excellent and still available.


이것은 공공 장소 및 악기용, 하이파이 장비의 수요를 충족시키기 만든 6L6 튜브의 최신 버전입니다.
30w 기준 플레이트 전압에서  500 볼트,  5w 스크린 사양에서 450 볼트의 헤비급 스펙이다.  이 튜브는 사실상 다른 모든 6L6 튜브 종류에 대치할 수있다.
이들은 곧은 양면 유리관 형태이고, 대부분이 1950 년대 후반 이후에 생산되었다.
이것은 현재까지 만들어 지고있는 유일한 6L6 유형이며 주의점은 현대관 일부에서 플레이트나 스크린에 최대 전압을 걸면 사망할 수 있다.
그 중 가장 좋은 것은 1960 년대 후반까지만 생산했던 RCA blackplate 이다
그러나 다른 종류의  grey plate의 미국산 NOS 버전도 사용할 만 하다


6L6GA / 6L6GB:

These two types are nearly identical, and as far as electrical ratings are the same. They are also the same as most of the 6L6 metal types listed below.
The GA was found in a smaller coke bottle ST shape with shoulders on the glass, the GB was almost always a short tubular glass tube looking much like a 6L6GC.
These were only rated at 360 volts and 19 watts on the plate, so they will NOT replace a 6L6GC if that is what your amp calls for! Some of the GA tubes
were "greyglass" meaning they had a conductive grey or black coating sprayed on inside the glass. This does not mean the tube is burned out, but both clear
and grey glass versions are interchangeable.

이 두 종류는 전기적 사양이 동일하다. 또한 아래의 6L6 금속관과도 대부분 동일하다.
GA형은 주로 작은 콜라병 같이 어깨가 있고 GB형은 GC형 같이 짧은 유리관 형태이다.
이들은 플레이트 전압 360볼트 19W 정도이므로 6L6GC 사양의 앰프에는 대체할 수없다.
일부 GA형은 회색관 형태로 이것은 관 안쪽에 회색이나 검은색 전도성 코팅을 한 것으로 관이 타버린 것이 아니다.
그리고 회색 유리관 버전과  투명관 버전은 서로 대체할 수 있다

6L6G:

This is a large "coke bottle" tube, and was one of the earliest glass types of this tube. It has the same plate and screen ratings as the GA/GB types listed above,
and also of the 6L6 metal listed below. These are finding use again in home built amps, since they have a cool "retro" styling, and prices are still relatively low.



6L6:

The 6L6 without a suffix indicates the metal jacketed type. These were rather tall heavy black painted metal tubes, with a wide flange just above the octal base.
This tube shared the 360 volt, 19 watt plate ratings of the G, GA, and GB types. This is a fine sounding tube, often overlooked by those wanting the designer look of
the early glass types. As a result the prices are still low and supplies reasonably good. This was also the tube of choice for many tube tester manufacturers to use
as their calibration standard. The 6L6 metal tube was both rugged and very stable in it's electrical characteristics, making it an ideal reference standard. Hickok
even had a part number by which you could order one from the factory to use in calibrating your tester. These "calibration tubes" have by and large vanished from
circulation today. We are making available, in very limited quantities, carefully selected NOS metal 6L6 calibration tubes that we have documented as meeting
the specifications of a typical production 6L6 with respect to Gm and plate current draw. These may be used as a secondary calibration reference wherever
a "6L6 calibration tube" is called for in factory alignment procedures, or for spot-checks of your tester's current state of calibration.
There are usually not many in stock, as it requires testing many NOS 6L6 tubes to find one with the exact Gm and other characteristics,
and then cross-testing on a number of various brands of carefully calibrated testers to confirm the results. No wonder they are so hard to find today!




1614, 6L6Y, 1622:

This is a premium industrial version of the 6L6 metal type, with the similar electrical ratings. These also have metal jackets. They were often found in 1950s
high fidelity equipment, and are beginning to become scarce. The 1614 is a bit more powerful than the standard 6L6 metal and the G, GA, or GB. It can handle up to
375 plate volts, 300 screen volts, and 21 watts at the plate. The 6L6Y is virtually identical with the 1614 except it is made for the military. The 1622 is slightly
less powerful than the standard 6L6 tubes, with 300 plate volts, 250 screen volts, and 13.8 plate watts. Always check your amp specs before substituting a 1622,
to be sure it does not exceed the maximum values of this tube. As a general rule, the 1614 can replace any 6L6 type except for the GC, 7581, and KT66.




7581:

This is an industrial rated tube designed for industry and not common consumer use. It is roughly the same as the 6L6GC and is one of the few subs for the GC type tube.
It also has the same specs as the European type KT-66. There is also a 7581A which has slightly higher ratings of 35 watts on the plate. This was a glass tube.
Blackbase is what is commonly found, and brownbase for military stock. Some OEM types made for amplifier production had light beige colored bases.
The 7581, 7581A, KT-66, and 6L6GC are generally compatible with each other, and may be substituted in most cases for each other. Of course,
check with your amplifier manufacturer or dealer before any change in type of power tubes, as bias may be affected and may need to be readjusted in your amp.




KT-66:

This version is the European equivalent to the 6L6GC and the 7581 type. These often have a fairly large coke bottle ST shape, and are found in both clearglass and greyglass.
They can be used to replace virtually any 6L6 type. Most of those available were made by the Marconi-Osram Valve Co., under their Genalex label, or may be found with either
the "Marconi" or "Osram" label. A premium audiophile version was introduced in the late 1950s under their "Gold Lion" label. These were screened for audio use, with handwritten data sheets included in the box with the tube. The Gold Lion types are unmistakable with their elaborate metallic gold label bearing the lion and the words "Gold Lion" in gold script, often faded by time on genuine NOS tubes. BEWARE! After the mid 1970s these Gold Lion tubes were being in Russia! The fakes have a smaller yellow lion on the glass, and should only be priced at $25 each or less! The Genalex, Marconi, and Osram types used a grey, blue and white decal on the glass, with often (but not always!) a white box containing "KT-66" and the Hammersmith, UK factory codes, elsewhere on the glass. Sometimes these can be found in factory matched pairs. M-O Valve also made these for Mullard and other European brands, and even some late vintage Sylvania were actually M-O made. The rarest are those with blackplates, grey glass, black bases, and a cup shaped metal getter. There is also an American made version of the KT-66, made by GE, which also usually is marked 7581A in addition to KT-66. These are excellent
tubes on par or better than the vintage 6L6GC made by GE. They can be found in blackbase, brownbase, and light beige colored bases that were usually made for OEM use in amplifiers.




EL37:

This is the European version of the 6L6. It was nearly always glass, and can be used to replace any 6L6, G, GA, or GB type, or 5881 as long as your amp does not put more
than 360 volts on the plate and 270 volts at 2.5 watts on the screen. These types are said to sound better than the USA versions, and are very scarce in America, as well.
Mullard is the brand most often encountered in the NOS market.



5881 / 6L6WGB:

This type originally was known as the 6L6WGB, and was designed for the US military. Nearly all were made by Tung Sol. The tube is a short flat topped tube with a brown base,
and a large grey plate structure inside. These often had large top getter patches, but there are some with side getters. The design proved so popular that an industrial
version was created and labeled the 5881. Both tubes are the same. These are slightly more powerful than the 6L6 standard types, having 360 volts at 23 watts on the plate
and 270 volts at 3 watts on the screen. They can replace any 6L6 type except for the GC, 7581, or KT66. They MAY POSSIBLY be used as a sub for these tubes, but ONLY if your
amp does not exceed the ratings of the 5881! Most amps calling for a 6L6GC type will exceed these ratings and the 5881 may overheat or arc over, so check first before
subbing these! This is a fine tube used in many high fidelity amps, and packs a wonderful sound into a small package. Found also in RCA, GE, Sylvania and other brands,
but nearly all were made by Tung Sol.




5932 / 6L6WGA:

A military type of 6L6GA, short and very fat, thick glass, blackplates, with large brown micanol bases. Sometimes late 1940s military stock turns up and these look more
like a cross between a 6L6G and a Western Electric 350B, with an ST coke bottle shape envelope. These share the ratings of the type 6L6, G, GA, and GB. They are built
to take a beating, and may be a long lasting choice if replacing any of the above 6L6 types. Said to be among the best sounding outside of the 6L6GC blackplate types,
but they are very scarce.




350B / 350A:

This is a large coke bottle shaped tube with black plates, usually only found in the Western Electric, Tung Sol, or National Union brand (made by W-E).
This tube has roughly the same specs as the 6L6GC and KT66 varieties. The 350B has the standard octal base, while the 350A has the old-fashioned 5-pin base with
no center plastic keyway pin, and the plate connection on a top metal cap. These 350s are said to be the best sounding of this family, on par with the best of the
Genalex Gold Lion series, but are very scarce. Western Electric tubes were noted for quality and long life, so if you find a pair, it may be worth your while to try them out!
For most applications calling for a 7581, KT66, or 6L6GC these tubes will work fine and sound great. They do have different filament current draw specs and other
slight differences, so you should always check with the amp manufacturer, dealer, or a tech before subbing these tubes in place of the stock tubes.







sound


350B, KT66, and EL37 types

These are generally in a class by themselves. The 350B is the king of the 6L6 types with an incredible, palpable air and depth to the sound with razor sharp focus
and dynamic power. It is not always compatible with all amps due to its different current draw and filament demands. The British NOS KT66 also rule in this category
and are usually compatible with any 6L6GC circuit, ditto the EL37. Warm and rich, like most of the British tubes, again with nice power reserves.
The EL37 only a little less powerful and getting harder to find every day. There is a USA KT66 called the 7581A and it is virtually the same as a 6L6GC,
and are found mostly made by GE. Clean, detailed, airy, and powerful. The beige base version made for amps is superb and the rarest of this type.
These types listed here are usually used in hi-fi applications, but the KT66 is sometimes favored for a British sound in guitar amps that call for a 6L6GC.




6L6GC types

Most needed for guitar amps but these make a fine hi-fi tube in any amp calling for a KT66, 7581, or even 5881. The blackplate RCA are the stars, and rightly so.
They are rich, warm, detailed, creamy, and powerful. No other tube comes close except possibly the NOS GE 6L6GC. The GE is a bit more linear from top to bottom
and lacks some of the RCA richness, but we are still talking about the two best NOS tubes in this class! The GE is often much less costly, but this may change
as they become scarce. Sylvania made this tube for many other brands. They are typically bright and sparkly, if a bit leaner in the bass.
Usually the Sylvania made NOS tube is the winner when it comes to bargain performance. Do not overlook some of the current production tubes.
The few that deserve attention are the JJ from the Slovak Republic, and the Winged C from SED, St. Petersburg, Russia. Both have near-NOS sonics at a much lower price.
The 6L6GC type can substitute for any of the types below, but may require a bias adjustment or modification to operate at peak performance.
Consult an amp tech whenever substituting tube types.




5881 and 6L6WGB types

The Tung Sol is the most asked for tube here. The original 1950s and 1960s brown base tubes, often found made for the military (JTL5881 or JAN 6L6WGB used interchangeably)
are smooth, detailed, and nearly as powerful as the 6L6GC types. They have great warmth yet balanced by smooth airy highs and wide dynamics. The GE and Sylvania
are the next best thing and the choice if cost is a consideration. These brownbase tubes often have a silver getter spot on the side only, and both USA
and Canada versions are equally excellent. These are brighter and leaner sounding, but often one-third less costly than the Tung Sol. Finally,
the JAN Philips 6L6WGB with the green or blue labels are a super bargain but are getting hard to find. They were late 1970s made in the USA, and are somewhat bright sounding,
but often priced far lower than either of the above types. This may change as stocks become depleated. Generally, guitar amps that call for a 6L6GC cannot use these tubes
without bias circuit adjustments or even modifications. Consult an amp tech if you are unsure.




5932, 1614, 6L6Y, and other glass 6L6G/A/B types

The metal 1614 and 6L6Y types enjoy a fine reputation in some McIntosh amps. The RCA are the ones most often requested, with fine dynamics, rich warmth,
and detailed, airy highs. The 5932 glass military type can often be used in place of these (or any other except for the GC, KT66 or the 5881) and in this case
the Sylvania is what is often found. They are powerful for their size, with a nice punchy and lively sound. Finally, the lower power 6L6 metal, 6L6GA and 6L6GB
come in many NOS brands. The RCA is the warmest, the GE fairly balanced, and the Sylvania the brightest of these. The large G shapes are said to be the most musical.
Like the 5881 types, these cannot be used in an amp calling for a 6L6GC or KT66 without at least bias adjustment or more likely, circuit modifications.
Consult an amp tech if you are unsure.