# The 6SN7 Identification Guide



## adhoc

*0. Introduction & preamble*

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*[size=large]
 While every effort is taken to maintain the accuracy of this thread, mistakes do get through. Please let me know if you find any! Thanks! [/size]*



*Version history*
 1.0 - 05/12/2006 - Original thread set up


*A quick note regarding nomenclature: *
 ‘6SN7’ is not an actual tube designation – the earliest designation was ‘6SN7GT’. In this thread, ‘6SN7’ is loosely used as a ‘master term’ to refer to 6SN7GTs, 6SN7GTAs, 6SN7GTBs, 6SN7Ws, etc – in other words, all the available permutations of the 6SN7GT tube. It is interesting to note though that European tube manufacturers sometimes just labeled tubes ‘6SN7’.



*This thread is divided into 6 sections:*

 0. Introduction and Preamble (this post)
1. VT-231s
2. US-made NOS 6SN7s
3. 5692s
4. European NOS 6SN7s
5. Other non-US NOS 6SN7s


*And so it begins…*

 This thread archives the physical construction of popular NOS 6SN7 tubes, with the aim of helping tube buyers make informed purchases. Tube relabeling was indeed common ‘back in the day’, but a tube’s construction will *always* betray its true origins. 

 More disturbingly, as the demand for NOS 6SN7s rises, so will the number of unscrupulous sellers counterfeiting tubes with intent to make a quick buck. The information contained here is the best weapon tube lovers can use against such counterfeiters.

 The 6SN7GT tube type was formally registered in 1941 by RCA and Sylvania. The 6SN7GT is an octal base medium-mu (20) [i.e. medium amplification] double-triode tube. It runs on a heater current of 0.6A (@ 6.3V). The 6SN7GT type is essentially two 6J5-type single-triodes within a single envelope.

 The 6SN7GT is the direct descendant of the straight sided 6F8GT. This in turn was a straight-sided glass envelope which descended from the ‘coke-bottle’ shaped 6F8G. 

_[Tube nomenclature 101: having a lone ‘G’ designation after the tube type indicated that the tube utilized a ‘shoulder-tube #12’ type glass envelope; the ‘coke-bottle’ shape. A ‘GT’ designation in turn meant that the tube had a straight-sided glass envelope.]_

 The 6F8G was a first attempt at placing two 6J5G triodes in a single envelope, but was unpopular due to its unwieldy shape and top grid cap, which necessitated extra connectors.


*6SN7 equivalents*

 There are a few direct electrical equivalents of the 6SN7GT, and they are as follows:

*7N7* – short lived loktal base version registered by Sylvania/Raytheon in 1940
*CV1988* – British designation; Civilian Valve #1988. Made by Brimar.
*6N8S* – Soviet designation, still in use today
*B65* – metal based tube produced by the Marconi Group of companies
*13D2* – Brimar made ‘industrial’ 6SN7GT (many GE manuals wrongly characterize this tube as having a 12.6V heater.)

*It is useful to note that the following types, namely:*

 ECC32
 ECC33
 5692* (see note below)

 …are, contrary to popular belief, *not* perfect electrical equivalents of the 6SN7 type. Substituting these tubes in place of 6SN7s in your equipment may result in damage. 

 *: 5692 types can be run at 6SN7 specifications and function identically even though they were technically not designed to do so (more on that later). 

 More commonly, unique nonlinearities in amplification caused by deviation from 6SN7 specifications lend characteristic ‘sounds’ to these tube types. These unique ‘sounds’ in turn are often misconstrued as being ‘better’ – a notable example of this would be how the ECC32 type is often perceived to have ‘better sound’ due to it’s higher gain. The human mind gives preferential attention to louder sounds, and the result of substituting ECC32s in place of 6SN7s is more often than not subjectively perceived to be ‘better’.


*6SN7 variants*

 The 6SN7A and 6SN7W were both short-lived designations for 6SN7GTs made to military specifications. Their construction included an additional ‘free-standing’ support post between the micas for greater vibration tolerance. It is likely that there were little, if any, additional selection criteria imposed upon A/W designations that were not already fulfilled by GT specifications. These designations used from (approximately) 1941 to 1945.

 The VT-231 (‘Vacuum Tube #231’) designation was used throughout WWII by the US Army Signal Corps. It should be noted that the term ‘VT-231’ was simply an inventory control number and thus lends no special significance to the tube so labeled. There is a full section devoted to VT-231 and JAN tubes later in this post.

 The 6SN7GTA and GTB versions were introduced in 1950 and 1954 respectively. They have ‘upgraded’ ratings, which are as follows.

 GTA: maximum anode dissipation upgraded to 5W (the GT is rated for 2.5W) 
 GTB: identical to the GTA, but with a controlled heater warm up time for use in equipment with 600mA heater strings

 This is significant because it means that a circuit designed around the 6SN7GTA/GTB cannot have 6SN7GTs substituted into it. Substituting a GT in place of a GTA/GTB in your equipment will precipitate its rapid destruction and possibly damage your equipment.

 Tubes labeled 6SN7GTC were made in the late 60s and early 70s. They are electrically identical to 6SN7GTBs but have their glass envelopes replaced by black colored metal envelopes. These tubes were mostly manufactured in South America.


*VT-231s and ‘JAN’ rated 6SN7s*

 The VT-231 designation was a military inventory control number, and should be taken as nothing more than that. Assuming identical construction, there is zero difference between a tube labeled VT-231 and a 6SN7GT of the same vintage. A lot of mystique has been built up around VT-231 labeled tubes by tube sellers, and many people mistakenly believe

 ‘JAN’ stands for ‘Joint Army-Navy’, and was meant to indicate that the tubes labeled as such were ‘passed’ for military use. However, no additional criteria that were not already fulfilled by the 6SN7GT specification were known to have been imposed. ‘JAN’ labeled tubes are identical to non-JAN tubes of the same vintage and construction.

 The ‘JAN’ naming convention was always written as follows:

 JAN-<manufacturer>-<tube type>

 Thus examples of JAN ratings would include: JAN-CTL-6SN7GT, JAN-CHS-5U4G, JAN-CRC-6AS7G, etc.

 JAN manufacturer abbreviations:
 CHS – Sylvania
 CHY – Hytron or CBS-Hytron
 CKR – KenRad
 CL – GE
 CRC – RCA
 CRP – Raytheon


*5692 types*

 The 5692 was designed by RCA in response to a particular problem involving radar-controlled artillery pieces. Bouts of intense vibration (while firing) were rapidly destroying 6SN7GT types in such equipment. The 5692 was designed to withstand such stress, and has extra rugged construction with features such as an extra top mica, 5 additional freestanding support posts and a low profile. The 5692 was patented in 1948 but not produced till 1951. 

 5692 types were advertised as a 6SN7GT substitute that had a vastly extended lifespan – 10,000hours. This outlandish claim, however, falls apart when you examine the recommended operating specifications of the 5692. The 5692’s recommended operating parameters are much lower than those of the 6SN7GT; any 6SN7GT would last far longer (maybe even 10,000hours?) when run at 5692 ratings.

 There are 2 ‘general types’ of 5692s – red bases and brown bases. The red bases in particular may have their color vary from a bright cherry-red to a dark, deep red easily confused with brown.

 Who actually produced 5692s in the USA is a controversial issue amongst tube lovers; here are some of the competing theories:

 -All red base 5692s were made by RCA.
 -All red base 5692s were actually made by GE, but for RCA (explains the high incidence of GE labeled red bases).
 -All brown base 5692s were made by CBS-Hytron.
 -Raytheon made a brown base 5692.
 -Sylvania made a brown base 5692.
 -Westinghouse made a brown base 5692.

_[*My *opinion, based on personal experience, is that GE made red-based 5692s for RCA, and that CBS-Hytron (earlier) and Sylvania (later) made brown-based 5692s.]_

 There is only one known European equivalent of the 5692 type: a Swedish-made brown base version designated either 33S30A or 33S30B.

 In the late 1960s, 6SN7GTBs were often relabeled as 5692s. Remember – if the construction doesn’t include the special features unique to 5692s (mentioned earlier), it isn’t a ‘real’ 5692.

 (Very) rarely, 5692s have been known to be labeled as 6SN7GTBs.


*A note on glass colour (‘smoked’ glass tubes)*

 Tubes with black or grey glass were only made en-masse till the early 1950s, after that they become vanishingly rare. What happened?

 The black/grey coat was a carbon/graphite coat, designed to prevent electrons from massing on the glass and exerting an undue influence on tube operation (massed negative charges). 

 Whether its eventual disappearance was the result of cost-cutting measures, or the introduction of new glass that was somehow resistant to this electron massing is unknown.


*** Descriptive terms used in this guide ***
_
 This guide uses descriptive terms liberally. To prevent confusion, they are defined as follows:_

*Base: *Bases were almost always made of plastic (Bakelite?). Brown bases are usually made of micanol, a ‘low loss’ material – 6SN7s with micanol bases are sometimes designated 6SN7GTY. Rarely, some bases are ‘metal’ – a metal (nickel alloy) strip was wrapped around the glass base of a tube and glued on. These metal strips will corrode if improperly stored and often fall off due to old age. Some tubes produced in the late 1960s to 1980s come with ‘button’ bases – the plastic base is no longer a large cylinder but looks more like a plastic button affixed to the bottom of the tube instead.

*Glass: *Almost all 6SN7s have straight sided glass envelopes. Glass may either be ‘smoked’ (blackened or greyed) or clear. Glass envelopes often vary slightly in height even amongst examples of identical construction and vintage, but generally fall into 2 broad categories – ‘tall bottle’ and ‘short bottle’. An extreme example of a tall bottle 6SN7 would be the Sylvania VT-231 while the opposite would be any 5692 tube.

*Getter:* More accurately known as ‘getter flashing’. A getter is the silvery coat of pure barium metal deposited on the inside of a tube to ‘get’ (react with) free gas molecules within the tube, which would otherwise interfere with tube operation. A ‘top getter’ is located at the top of the tube, a ‘bottom getter’ is located at the bottom of the tube, and so on and so forth. 

 When referring to the getter ‘shape’ we are talking about the ‘getter holder’. The getter holder is a structure within the tube that held the barium metal before it was ‘flashed’ onto the inside surface of the tube. Common getter shapes in 6SN7s include ‘ring’ (also known as ‘O’), ‘D-shaped’, ‘foil’ (looks like a piece of aluminum foil), ‘square’ (a square ring), rectangular (a rectangular ring) or ‘cup’ (looks like an inverted cup).

*Mica: *Mica is a naturally obtained mineral, and is used extensively in tube construction due to its ability to withstand high temperatures whilst maintaining its electrically insulative properties.

 Micas are located near the top and bottom of tubes, and are described in terms of their location and shape. An example would be ‘round top mica with rectangular bottom mica’. Descriptors such as ‘round’, ‘rectangular’, ‘square’ and ‘racetrack’ are self-explanatory. A ‘scalloped’ mica is a mica that looks as though a creature has taken a small nibble out of the edge at regular intervals. A ‘spiked’ mica is one that has little spikes extending out. Scalloped and spiked micas can occur with any mica shape. 

*Mica spacers:* Mica spacers are pieces of mica attached anywhere within the tube that serve to brace the internal construction against the glass to improve its vibration resistance. 

*Plate: *Plates are more correctly known as ‘anode plates’, and are the large metallic structures that extend between the top and bottom micas. There are always 2 separate plates in 6SN7 tubes. They are described in terms of color and shape. Color is self-explantory – plates are usually either grey or black. Shape is a little more tricky though.

 ‘T-plates’ (also known as ‘box plates’) are plates that have a ‘T’ shaped cross section.

 ‘Triangular plates’ are plates that have a triangular cross section.

 ‘Flat-plates’ are not actually perfectly flat, but have thin and long rectangular cross sections.

 ‘Round-plates’ or ‘oval-plates’ are plates that have a circular or oval cross section.

 ‘Ridged’ (or ‘embossed’) refers to the raised shapes stamped onto the plates. These often have a pattern that looks somewhat like a ladder. 

 ‘Smooth’ plates are plates that have no ridging/embossing on them – in other words, perfectly smooth.

 ‘Angled plates’ are plates that are at strange angles to each other – in other words, not directly mirroring each other in placement and orientation.

 ‘Staggered plates’ are flat-plates that are parallel to each other, yet at a ‘funny’ angle when viewed from above, like this: / / or \ \ (as opposed to | | or =)

 Examples of plate descriptions would include ‘black T-plates’, ‘grey staggered flat plates with ladder ridging’, etc.

*Support posts: *support posts are additional metal posts that extend between the top and bottom micas and serve to brace the tube internals against vibration.


----------



## adhoc

*1. VT-231s*

*Hytron *
_Hytron was bought by CBS in 1952. Tubes made by Hytron post-1952 have ‘CBS-Hytron’ or plain ‘CBS’ labeling. _
 Base: black with white labels
 Glass: clear
 Plates: black, T-plates
 Getter: bottom, rectangular, flashing rarely extends up past plastic base
 Top mica: rectangular
 Other significant features: top and bottom micas are identical


*KenRad*
 Base: black, white labels sometimes written in a ‘gothic’ font
 Glass: black (very common) or clear (less common)
 Plates: black, flat with ‘ladder’ ridging, ‘staggered’ arrangement
 Getter: bottom, flashing extending up to 1/3 of the way up tube
 Top mica: rectangular with 3 spikes on both shorter sides
 Other significant features: line of small holes down longitudinal midline of top mica. Protruding grid posts and plate anchors on top mica have distinctive ‘staggered’ pattern.


*‘National Union’*
_National Union never made a tube labeled 'VT-231'. However, National Union did make a JAN-rated 6SN7GT (JAN-CNU-6SN7GT). These came in 2 flavors – (earlier) grey glass and (later) black glass. Check the US-made 6SN7GT section for more on National Union 6SN7GTs._


*RCA*
 Base: black with silver labels
 Glass: grey extending right from base to near the top, usually opaque
 Plates: black (difficult to see except with a very strong torchlight)
 Getter: bottom, flashing extending up past plastic base
 Top mica: round
 Other significant features: 2 stabilising rectangular mica ‘ears’ on either side of round top mica. Mica ears often ‘scratch’ out trails in the grey glass.


*Raytheon version 1 (T-plates) *
_Earliest known version of VT-231_
 Base: black with orange-yellow labels
 Glass: clear
 Plates: black, T-plates
 Getter: bottom, flashing rarely extending up past plastic base
 Top mica: racetrack shaped with 4 spikes coming off either shorter side
 Other significant features: bottom mica identical to top mica. No support rods.


*Raytheon version 2 (Flat plates) *
_Chronologically, the next version of Raytheon VT-231s._
 Base: black with orange-yellow labels
 Glass: clear
 Plates: black, flat with ‘ladder’ ridging. 
 Getter: bottom, flashing rarely extending up past plastic base
 Top mica: racetrack shaped with 4 spikes coming off either shorter side
 Other significant features: Bottom mica identical to top mica. 2 metal supporting rods between top and bottom micas. 2 supporting rods are ‘free-standing’ and are not attached to anything aside from the two micas.


*Raytheon version 3 *
_Unknown vintage. Rare._
 Base: black with orange-yellow labels
 Glass: clear
 Plates: black, flat with ‘ladder’ ridging.
 Getter: bottom, flashing rarely extending up past plastic base
 Top mica: racetrack shaped with 4 spikes coming off either shorter side
 Other significant features: 2 ‘free’ copper support posts. Bottom mica identical to top mica. Top mica has ‘spring-loading’ of plates (black U-shaped structures)


*Sylvania *
 Base: black, white labels (rarely yellow)
 Glass: clear 
 Plates: black, T-plates
 Getter: bottom, foil, flashing extending up to 1/3 of the way up tube
 Top mica: rectangular
 Other significant features: micas may appear whitish. Bottom mica may be slightly smaller than top mica.


*TungSol *
 Base: black, white labels
 Glass: black glass extending from bottom of tube to ¾ up
 Plates: round plates, ‘keyhole’ appearance when viewed from above
 Getter: bottom, foil, very hard to see
 Top mica: round with small spikes on opposite sides (earlier; 19??-42) or oval (later; 1942-46)
 Other significant features: spring-loading of plates (U-shaped structures) on top mica. U-shaped structures may face same or opposite directions. Tubes with oval micas have long thin metal pieces affixed to the opposite edges of their micas to brace them against the inside of the glass. Oval mica tubes have the bottom mica identical to the top mica, sans metal bracers.


----------



## adhoc

*2. US-made NOS 6SN7s*

*CBS / CBS-HYTRON / HYTRON 6SN7GT*
_Also JAN-CHY-6SN7GT
 Tubes marked “Hytron” came first, followed by “CBS-Hytron”, then lastly by plain “CBS”. The construction between these 3 tubes appears identical._
 Base: black, white (Hytron, CBS-Hytron) or red (CBS) print
 Glass: clear, tall-bottle always
 Plates: black, T-plates, 2 holes per plate
 Getter: bottom, square, flashing rarely extends past plastic base
 Top mica: rectangular
 Other significant features: bottom mica also rectangular


*CBS 6SN7GTA*
 Base: black with red labels
 Glass: clear, midway between tall and short bottle height
 Plates: flat, black
 Getter: ???
 Top mica: racetrack with spiked shorter edges
 Other significant features: bottom mica same shape


*CBS 6SN7GTB*
 Base: black with red print, base is slightly shorter
 Glass: clear, short bottle
 Plates: ???
 Getter: side
 Top mica: ???
 Other significant features: 


*GE 6SN7GT *
_Check the non-US NOS 6SN7 section._


*GE 6SN7GTA*
_Made up till around 1955._
 Base: black, white printing
 Glass: clear, has 6SN7GTA etched into it on side, short bottle 
 Plates: dark gray (often called black), large flat-plates with ‘ladder’ ridges 
 Getter: side, D-getter, flashing covers a circular patch inside tube
 Top mica: round with spiked edges, has 2 anode plate ‘tabs’ per plate on top mica (4 total)
 Other significant features: bottom mica is racetrack shaped


*GE 6SN7GTB*
_Often confused with the GE 6SN7GTA. _
 Base: black, white printing
 Glass: clear, has 6SN7GTB etched into it on side of glass
 Plates: light gray, large flat-plates with ‘ladder’ ridges
 Getter: side, D-getter, flashing covers a circular patch inside tube
 Top mica: round with spiked edges, has 2 anode plate ‘tabs’ per plate on top mica (4 total)
 Other significant features: bottom mica is racetrack shaped


*KenRad 6SN7GT *
_Also JAN-CKR-6SN7GT
 KenRad stood for ‘Kentucky Radio’. KenRad was bought by GE around the mid-1940s and ceased to exist as a brand name by the early 1950s. Military tube boxes from the 1940s are labeled with “KenRad, Division of General Electric Corp”. The construction of this tube is identical to the KenRad VT-231 tube (both clear and black glass). _


*National Union (NU) gray glass 6SN7GT *
_Also JAN-CNU-6SN7GT
 Earliest 6SN7GT vintage by NU. RCA round mica 6SN7GTs are often relabeled as NU and do look extremely similar. Look to the top mica spacers for confirmation of identity – RCA (rectangular) vs NU (square). _
 Base: black with white or silver labels
 Glass: gray. Gray glass extends from base upwards to almost cover the top. Occasionally found as short bottles.
 Plates: gray glass - black, flat-plates
 Getter: bottom, 
 Top mica: round, with square mica spacers on opposite sides
 Other significant features: twoU-shaped structures on top mica. Bottom mica identical to top mica. 


*National Union (NU) black glass 6SN7GT version #1*
_Also JAN-CNU-6SN7GT
 Later vintage. Version 1 – round plates. Tooling similar to 6SL7GT_
 Base: black with white or silver labels
 Glass: black. Black glass begins ¼ of the way from base and ends near the top.
 Plates: gray, round plates, circumference of plates larger than that of Tungsol VT-231
 Getter: bottom, foil, flashing rarely extends up past base
 Top mica: circle with spiked edges, spikes come into contact with glass
 Other significant features: Bottom mica identical to top mica. 2 free-standing supporting rods.


*National Union (NU) black glass 6SN7GT version #2*
_Also JAN-CNU-6SN7GT
 Later vintage. Version 2 – flat plates, rectangular top mica._
 Base: black with white or silver labels
 Glass: black. Black glass begins ¼ of the way from base and ends near the top.
 Plates: black, flat plates
 Getter: bottom, foil, flashing rarely extends up past base
 Top mica: rectangular with spiked shorter edges that contact glass.
 Other significant features: Bottom mica identical to top mica. 


*National Union (NU) black glass 6SN7GT version #3*
_Also JAN-CNU-6SN7GT
 Later vintage. Version 3 – flat plates, round top mica._
 Base: black with white or silver labels
 Glass: black. Black glass begins ¼ of the way from base and ends near the top.
 Plates: black, flat plates
 Getter: bottom, rectangular, flashing rarely extends up past base
 Top mica: round with 2 mica spacers 
 Other significant features: rectangular with spiked shorter edges that contact glass


*Raytheon 6SN7GT*
_Also JAN-CRP-6SN7GT. 
 3 versions identical to 3 VT-231 iterations – read Raytheon VT-231 section for details.

_
*Raytheon 6SN7WGT*
_Also JAN-CRP-6SN7WGT_
 Base: brown with red or yellow print (red print is earlier)
 Glass: clear
 Plates: black, flat with ‘ladder’ ridging, shiny
 Getter: top, square, flashing may be slightly small
 Top mica: round with 4 ‘umbrella spokes’ extending downwards from edge
 Other significant features: 2 black U-shaped structures on top mica, bottom mica also round


*Raytheon 6SN7GTA*
 Base: black
 Glass: clear
 Plates: gray, 
 Getter: side getter, 
 Top mica: ???
 Other significant features: 


*Raytheon 6SN7GTB*
 Base: black with yellow print
 Glass: clear, short bottle
 Plates: black, flat with ladder ridging 
 Getter: side, D-shaped ‘wrapped’ around plates
 Top mica: round with 2 sides spiked
 Other significant features: bottom mica identical to top mica


*Raytheon Uniline 6SN7GTB*
 Base: black with yellow print
 Glass: clear, tall bottle
 Plates: gray, flat with ladder ridging
 Getter: top, ring 
 Top mica: racetrack with spiked shorter edges
 Other significant features: bottom mica identical to top mica


*RCA 6SN7GT version #1 *
_Also JAN-CRC-6SN7GT. 
 Earlier vintage. Identical to RCA round mica VT-231 except not labeled ‘VT-231’ but having ‘RCA’ in a circular logo (with a lightning bolt) labeled in silver print on the base. Made till 1949._


*RCA 6SN7GT version #2 *
_Also JAN-CRC-6SN7GT 
 Later vintage - made from 1949 onwards._
 Base: black, silver print, “RCA” in “tall and narrow” script
 Glass: gray, opacity varies; may sometimes be almost transparent – later vintages seem to have less blackening. Glass blackening often starts some distance from tube base (contrast to earlier versions)
 Plates: black, flat with ladder ridging
 Getter: bottom, flashing rarely extends up past base
 Top mica: racetrack shaped (contrast to round mica earlier versions) 
 Other significant features: no top mica spacers. 


*RCA 6SN7GTY*
 Base: light brown micanol, black labels
 Glass: gray
 Plates: blackened (blackening is inconsistent) flat plates
 Getter: bottom, rectangular, flashing rarely extends up past base
 Top mica: racetrack shaped
 Other significant features: bottom mica is racetrack shaped with spiked shorted edges. 


*RCA 6SN7GTA*
 Base: black, silver labels
 Glass: clear
 Plates: black, large flat plates with ‘ladder’ ridging
 Getter: side, flashing covers a circular patch on the side of the tube.
 Top mica: racetrack
 Other significant features: bottom mica is same as top mica


*RCA 6SN7GTB*
 Base: black, silver labels
 Glass: clear
 Plates: black, flat-plates
 Getter: side, small flashing on side
 Top mica: racetrack
 Other significant features: bottom mica same as top mica


*RCA 6SN7GTC*
 Base: black plastic
 Glass: no glass. Made of metal
 Plates: unknown
 Getter: unknown
 Top mica: unknown
 Other significant features: made in South America throughout the 70s. 


*Sylvania 6SN7GT version #1*
_Also JAN-CHS-6SN7GT
 Identical to VT-231s except:
 - Green printing seen on black base; white labels are much rarer.
 - Made in the 1950s.
 - Flat plate versions exist across all year of make (very rare)._
 Base: black, green labels, triangular Sylvania logo with ‘lightning bolt’ through logo.
 Glass: clear
 Plates: black, T-plate, (or rarely, flat black plates) with 2 holes per plate
 Getter: bottom, foil, flashing can extend up to 1/3 of way up tube
 Top mica: rectangular, (flat plate versions have round top and bottom micas)
 Other significant features: when seen, date codes are vertically arranged (from top to bottom) ‘YWW’ with Y underlined. Y = last digit of year, WW = week number of year.


_A note on Sylvania Chrome Domes: 
 The “Chrome Dome” moniker was first applied to particular early 1950s vintage Sylvania 6SN7GTs by tube enthusiasts. The name came about in response to the tube’s appearance – it had a beautifully shiny top getter flashing that nearly reached the bottom of the tube, obscuring almost all of the internal construction from view.

 These particular 6SN7GTs are extremely rare, and as time passed, people began applying the “Chrome Dome” moniker to many other Sylvania tubes with top getter flashing.

 The following Sylvania tubes are often (incorrectly) called ‘Chrome Domes’:
 6SN7GTA
 6SN7W
 6SN7A
 6SN7WGT
 6SN7WGTA_


*Sylvania 6SN7GT version #2 “Chrome Dome”*
 Base: black, often unlabeled, sometimes simply labeled “Sylvania”
 Glass: clear
 Plates: black, T-plates
 Getter: top, foil, flashing extends down to cover nearly all of the tube
 Top mica: unknown
 Other significant features: bottom mica rectangular 


*Sylvania 6SN7GT 1952 “Bad Boy” *
_Also JAN-CHS-6SN7GT
 Made only from late 1951 (‘1-48’ examples seen) to 1952. Differs slightly in construction from ‘regular’ Sylvania rectangular top mica 6SN7GTs. Re-labeled bad boys are known to exist._
 Base: black, green labels marked ‘2-XX’ (where XX is the week of the year)
 Glass: clear
 Plates: black, T-plate with 3 holes per plate
 Getter: bottom, foil, flashing can extend up to 1/3 of way up tube
 Top mica: rectangular with 3 spikes on each of the shorter edges
 Other significant features: bottom mica is rectangular. When seen, date codes are vertically arranged (from top to bottom) ‘YWW’ with Y underlined. Y = last digit of year, WW = week number of year.


*Sylvania 6SN7A / 6SN7W version #1*
_Also JAN-CHS-6SN7A/W
 Internal construction seems identical to the Sylvania metal base 6SN7A/W – only differences seem to be the height and base material._
 Base: black plastic with green or yellow print 
 Glass: clear, usually short bottle (tall bottle much rarer)
 Plates: black, T-plates, 2 holes per plate
 Getter: top, foil, getter flashing extends almost halfway down tube, foil getter (not usually visible)
 Top mica: round, has 4 ‘umbrella spokes’ extending downwards from edges of mica, U-shaped anode plate extensions (not usually visible) on top of mica
 Other significant features: bottom mica racetrack shaped, a single support post extends between micas


*Sylvania 6SN7A / 6SN7W version #2 “Metal Base”*
_Also JAN-CHS-6SN7A/W
 This tube is most often known as the ‘metal base 6SN7W’ – however, examples labeled 6SN7A are known to exist. 
 Base: metal with green or yellow print – metal is actually a single flat piece connected at one side to make a cylinder. If removed, ‘remaining’ plastic base looks surprisingly like a ‘button’ base 6SN7GT._
 Glass: clear, always tall bottle
 Plates: black, T-plates, 2 holes per plate
 Getter: top, foil, getter flashing extends almost halfway down tube, foil getter (not usually visible)
 Top mica: round, has 4 ‘umbrella spokes’ extending downwards from edges of mica, U-shaped anode plate extensions (not usually visible) on top of mica
 Other significant features: bottom mica racetrack shaped, a single support post extends between micas


*Sylvania 6SN7WGT*
_Also JAN-CHS-6SN7WGT or USN-CHS-6SN7WGTA_
 Base: brown with green labels
 Glass: clear, may have faint white labels
 Plates: black T-plates, has 3 holes per plate
 Getter: top, flashing extends about halfway down tube
 Top mica: round, top mica has 4 “umbrella spokes” extending downwards
 Other significant features: bottom mica round. 1 freestanding support post.


*Sylvania 6SN7WGTA version #1*
_Also JAN-CHS-6SN7WGTA_
 Base: brown, green print
 Glass: clear, may have green print on it
 Plates: angled black T-plates
 Getter: top, ring getter holder 
 Top mica: round with a few spikes 
 Other significant features: bottom mica identical to top mica


*Sylvania 6SN7WGTA version #2*
_Looks similar to the WGT._
 Base: brown, may have green print
 Glass: clear, may have faint white labels
 Plates: black T-plates, has 3 holes per plate
 Getter: top, flashing extends about halfway down tube
 Top mica: round, top mica has 4 “umbrella spokes” extending downwards
 Other significant features: bottom mica round. 1 freestanding support post.


*Sylvania 6SN7GTA*
 Base: black with green print
 Glass: clear, short bottle
 Plates: black T-plates, 3 holes per plate
 Getter: top, foil
 Top mica: rectangular with spiked shorter edges
 Other significant features: bottom mica identical to top mica


*Sylvania 6SN7GTB*
_Come with many label colors. For dating – red labels are later than green labels are later than yellow labels. _
 Base: black, label color varies, not a ‘full’ base
 Glass: clear 
 Plates: black, angled T-plates
 Getter: top, ring
 Top mica: round with 2 spiked sides
 Other significant features: bottom mica identical to top mica


*Tungsol 6SN7GT “Round Plate”*
_Also JAN-CTL-6SN7GT
 Construction identical to that of Tungsol VT-231. See VT-231 section for details._


*Tungsol 6SN7GT “Mouse Ears”*
 Base: black
 Glass: clear
 Plates: earlier vintages had black T-plates, later versions had gray T-plates
 Getter: bottom, flashing rarely extends up past base, square getter holder
 Top mica: rectangular, has 2 distinctive circular mica spacers making contact with the glass on each side (“mouse ears”)
 Other significant features: bottom mica also rectangular


*Tungsol 6SN7WGT*
_Also JAN-CTL-6SN7WGT_
 Base: brown, base is slightly shorter than most other 6SN7GT, white labels
 Glass: clear
 Plates: angled black T-plates
 Getter: top, D-getter holder
 Top mica: round with spiked edges
 Other significant features: bottom mica identical to top mica


*Tungsol 6SN7WGTA*
_Also JAN-CTL-6SN7WGTA
 Construction appears similar to WGT._
 Base: brown, base is slightly shorter than most other 6SN7GT, white labels
 Glass: clear
 Plates: angled black T-plates
 Getter: top, D-getter holder
 Top mica: round with spiked edges
 Other significant features: bottom mica identical to top mica


*Tungsol 6SN7GTB version #1*
_Construction appears similar to WGT/WGTA._
 Base: black with white print
 Glass: clear, tall bottle
 Plates: angled black T-plates
 Getter: top, D-getter holder
 Top mica: round with spiked edges
 Other significant features: 

*Tungsol 6SN7GTB version #2*
_Identical to version #1, except in short bottles rather than tall bottles._


----------



## adhoc

*3. 5692s:*

_This section is unusual in that the provenance of the tubes contained within it is still a topic up for debate._

*CBS-Hytron ‘Brown Base’ 5692*
_Possibly made by Raytheon instead._
 Base: brown
 Glass: clear, short bottle
 Plates: large black flat-plates, 
 Getter: top, small getter flashing
 Top mica: dual top mica, round with smooth edges
 Other significant features: bottom mica identical to top micas, 5 extra support posts


*RCA ‘Red Base’ 5692*
_Possibly made by RCA._
 Base: red; color varies from bright cherry red to deep burgundy red, labels are white (earlier vintage) or orange (later vintage)
 Glass: clear, short bottle
 Plates: large flat-plates
 Getter: top, small getter flashing
 Top mica:
 Other significant features: bottom mica identical to top micas, 5 extra support posts


*Sylvania 5692*
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Standard Electric 33S03A/B*
_Made in Sweden._
 Base: brown, speckled
 Glass: clear, short bottle
 Plates: large black flat-plates, blackening is inconsistent, one/both plates have numbers ‘scratched’ onto it/them
 Getter: top, small getter flashing
 Top mica: dual top mica, round with spiked edges
 Other significant features: bottom mica identical to top micas, 5 extra support posts


----------



## adhoc

*4. European NOS 6SN7s*

*Amperex 6SN7GTB*
_These tubes are likely Russian-made. Be wary of overpaying for them!_
 Base: black
 Glass: clear, orange Amperex labeling with globe logo, may have white ‘6SN7GTB’ labeling
 Plates: grey, T-plates
 Getter: bottom, ‘flying saucer’ getter holder, flashing extends a little bit past base, usually more so on one side
 Top mica: rectangular, has ‘spring-loading’ for plates (U-shaped structures)
 Other significant features: bottom mica identical to top mica. micas appear whitish. 2 support rods on either side between both micas.


*STC/Brimar 6SN7GTY / CV1988 (UK)*
_Brimar stood for ‘BRItish Made American Range’ and was originally part of STC (Standard Telephone and Cables), which in turn was the British agent of Western Electric. Only Brimar made the CV1988 – known relabels include Cossor, STC, Zaerix, ITT (International Telephone and Telegraph) and Mullard. Sometimes labeled as 6SN7GTY._
 Base: brown, no printing
 Glass: black or clear (less common), if applicable blackening extends up from ¼ from bottom of tube to top, white printing on glass with factory code FE (indicating STC Oldsway production)
 Plates: grey, ‘flattened oval’ cross section
 Getter: bottom, ring getter holder, flashing does not extend past base 
 Top mica: round with spiked edges, spikes contact glass, 2 small anode plates extensions extend vertically
 Other significant features: bottom mica round with smooth edges


*Brimar 6SN7GT (UK) version 1*
_This tube is identical to the CV1988 except that black bases may be used._
 Base: black or brown (less common) with printing
 Glass: black or clear (less common), if applicable blackening extends up from ¼ from bottom of tube
 Plates: grey, ‘flattened oval’ cross section
 Getter: bottom, ring getter holder, flashing does not extend past base 
 Top mica: round with spiked edges, spikes contact glass, 2 small anode plates extensions extend vertically
 Other significant features: bottom mica round with smooth edges


*Brimar 6SN7GT (UK) version 2*
_This tube came next chronologically and differs from earlier examples by not having anode plate extensions on the top mica and having a differently shaped getter holder. No black glass examples of this tube have been yet found by the thread author._
 Base: black with printing, printing may be reddish-orange
 Glass: clear 
 Plates: grey, ‘flattened oval’ cross section
 Getter: bottom, rectangular getter holder, flashing does not extend past base 
 Top mica: round with spiked edges, spikes contact glass
 Other significant features: bottom mica round with smooth edges


*Brimar 6SN7GT (UK) version 3*
_Latest vintage. Often found as Cossor relabels. Note the different top mica shape. No black glass examples of this tube have been yet found by the thread author._
 Base: black
 Glass: clear, often with Cossor labels 
 Plates: grey, ‘flattened oval’ cross section
 Getter: bottom, rectangular getter holder, flashing does not extend past base 
 Top mica: round, smooth edged
 Other significant features: bottom mica identical to top mica


*Brimar 13D2 (UK)*
_6SN7GT equivalent produced for industrial use. Extremely rare._
 Base: dark brown, no labels
 Glass: clear, has white labels printed onto it
 Plates: grey flat plates
 Getter: top, on top-most mica (more on that later), dual ring getter – one above each plate
 Top mica: 2 round top micas; top-most mica has smaller diameter than next top mica
 Other significant features: bottom mica round, diameter roughly same as top-most mica


*Cossor 6SN7GT (UK)*
_Cossor bought tubes in bulk, and then relabeled them. Tubes labeled ‘Cossor’ have been seen that were made from anyone from RCA to Brimar to Sovtek. _


*Fivre 6SN7GT (Italy)*
_Fivre stands for ‘Fabbrica Italiana Valvola Radiofonica Elettronica’. Original tube retail boxes are red and black._
 Base: black
 Glass: clear, has a colourful label on it 
 Plates: grey
 Getter: bottom, 
 Top mica: rectangular with a few ‘spikes’ on either short end
 Other significant features: 


*GEC B65 (UK)*
_GEC stands for ‘General Electric Company’._
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Haltron 6SN7GT*
_Haltron bought tubes in bulk, and then relabeled them. Tubes labeled ‘Haltron’ have been seen that were made from anyone from Brimar to Sovtek. Many were also made in eastern-bloc countries._


*Osram B65 (UK)*
 Base: metal base with no labels
 Glass: grey glass beginning ¼ of way from base, tube data print on glass
 Plates: 
 Getter: bottom, inverted cup, flashing rarely extending up past metal base
 Top mica: round with ‘umbrella spokes’ coming off bottom
 Other significant features: usually has color print ‘Osram’ logo on glass


*MWT B65 (UK)*
_MWT stands for ‘Marconi Wireless Telegraph’._
 Base: metal, no labels
 Glass: smoked, has colorful label on it, also may have (fragile) white print
 Plates: 
 Getter: bottom, inverted ‘cup’ getter, flashing does not extend much past base
 Top mica: round
 Other significant features:


*Neotron 6SN7 (France)*
_Commonly confused with TungSol round plate 6SN7GTs._
 Base: black
 Glass: smoked with orange “Neotron 6SN7” logo, black glass extends from base of tube
 Plates: round 
 Getter: bottom
 Top mica: rectangular
 Other significant features: top mica has two rectangular mica ears on it and two large U-shaped structures, (looks similar to Tungsol RP except for top mica shape)


*RFT 6SN7GT (West Germany)*
_An extremely unusual tube._
 Base: black, ‘short’ base
 Glass: clear with yellow RFT logo and labels
 Plates: grey, flat with NO ridging and an unusual ‘monolith’ look
 Getter: top, flat disc 
 Top mica: NOT mica, but *ceramic*! round with 2 mica ‘ear’ supports 
 Other significant features: bottom ‘mica’ is also made of ceramic, round and has ‘cutouts’ on 2 sides.


*Philips 6SN7GT (Holland)*
_Philips Holland had numerous subsidiaries - examples include: Adzam (exclusively an export name), Amperex, Pope (exclusively an export name), Philips Miniwatt, Mullard, Miniwatt, Miniwatt Dario, Radiotechnique, etc. This tube has been known to be relabeled with the following brand names: Pope, Philips Miniwatt, Miniwatt and Mullard._
 Base: black with white labels
 Glass: clear (less common) or grey-black (similar color and luster to pencil lead). If grey-black glass, begins ¼ of way up tube from base and ends near top. May have white print on glass (Mullard).
 Plates: grey, flat with ‘ladder’ ridging
 Getter: bottom, D-shaped, flashing rarely extends past plastic base
 Top mica: racetrack shaped
 Other significant features: bottom mica is racetrack shaped with mica ‘spikes’ coming off shorter sides


*Sicte 6SN7GT (Italy)*
 Base: black with orange print
 Glass: clear with a very colorful label
 Plates: grey
 Getter: bottom, flashing extending slightly up past base
 Top mica: rectangular
 Other significant features:


*Sovtek 6SN7GT (Russian)*
 Base: black
 Glass: clear, labels in silvery ink
 Plates: grey, T-plates
 Getter: bottom, ‘flying saucer’ getter holder, flashing extends a little bit past base, usually more so on one side
 Top mica: rectangular, has ‘spring-loading’ for plates (U-shaped structures)
 Other significant features: bottom mica identical to top mica. micas appear whitish.


*Telefunken 6SN7GTA (West Germany)*
_May be marked ‘Radiotron’ on base._
 Base: black, usually clear of any labels
 Glass: clear, white labels, says ‘Made in West Germany’
 Plates: grey, plates have 2 horizontal ‘holes’ midway in them
 Getter: top, ring, flashing is restricted to topmost portion of tube; does not extend down much
 Top mica: round with scalloped edges
 Other significant features: bottom mica is identical to top. Top of tube glass is obviously less ‘rounded’ than most other 6SN7s.


*Tungsram 6SN7GTY / CV1988 (UK)*
_Extremely rare._
 Base: brown
 Glass: black, blackening extends up from ¼ from bottom of tube to top
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Zaerix 6SN7GT *
_Zaerix was a company name owned by Z&I Aero, London, England. Zaerix, like Haltron, bought tubes in bulk, and then relabeled them. Tubes labeled ‘Zaerix’ have been seen that were made from anyone from Brimar to Sovtek. Many Zaerix tubes were also made in eastern-bloc countries. Zaerix bought tubes in bulk, tested them to ensure that they were within spec, and then relabeled and supplied them to the UK government and various OEM companies._


----------



## adhoc

*5. Other non-US NOS 6SN7s*

_Due to the relative rarity of these tubes this list is, in particular, not meant to be comprehensive. If you have any information regarding these tubes, please PM me. _

*GE 6SN7GT (JAN-CL-6SN7GT)*
_Made in Canada_
 Base: black, red labels
 Glass: clear
 Plates: black, T-plates
 Getter: bottom, rectangular, flashing rarely extends up past plastic base
 Top mica: rectangular 
 Other significant features: bottom mica same shape as top mica. Micas are nearly transparent. 


*RCA *
_Made in Canada_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica: square with 2 rectangular mica ‘ears’ either side, 
 Other significant features:


*AWV (Amalgamated Wireless Valve Co.) 6SN7GT*
_Made in Australia_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Miniwatt 6SN7GT*
_Made in Australia_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Mullard 6SN7GT*
_Made in Australia_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Radiotron 6SN7GT*
_Made in Australia_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


*Radiotron 6SN7GTA*
_Made in Australia_
 Base:
 Glass:
 Plates: 
 Getter:
 Top mica:
 Other significant features:


----------



## adhoc

_reserved post #1_

 (kept here in case of future additions)


----------



## adhoc

_reserved post #2_

 (kept here in case of future additions)


----------



## Frihed89

It is my understanding that only a small fraction of the Slyvania JAN-CHS-6SN7GTs are "bad boys". Is your description of the JAN-CHS-6SN7GT or the bad boy part of the production run? 

 If you are describing the bad boys, then how do the other JAN-CHS-6SN7GTs differ in construction from the bad boys?


----------



## adhoc

Quote:


  Originally Posted by *Frihed89* /img/forum/go_quote.gif 
_It is my understanding that only a small fraction of the Slyvania JAN-CHS-6SN7GTs are "bad boys". Is your description of the JAN-CHS-6SN7GT or the bad boy part of the production run? 

 If you are describing the bad boys, then how do the other JAN-CHS-6SN7GTs differ in construction from the bad boys?_

 

Hi there -

 Bad Boys were only made in 
 - late 1951
 - 1952 
 - early 1953

 Thus they will be marked with either 
 - '1xx' (late week production numbers only), 
 - '2xx' (all 52 weeks of the year) or 
 - '3xx' (early week production numbers only) 
 date codes. 

 They *can *also be JAN-rated and thus be marked JAN-CHS-6SN7GT.

 For construction details, look to the section on Bad Boys in post #3 and compare against that for 'normal' Syl 6SN7GTs.


----------



## Rob N

I've not seen any metal bases with yellow print.All the ones I've seen have had either black or green print


----------



## adhoc

Quote:


  Originally Posted by *Rob N* /img/forum/go_quote.gif 
_I've not seen any metal bases with yellow print.All the ones I've seen have had either black or green print_

 

For tubes, never say never. 
	

	
	
		
		

		
		
	


	









 Granted, this tube isn't labeled 'Sylvania' - but I have seen one Sylvania metal base with yellow labels. Just one. 
	

	
	
		
		

		
		
	


	




 Unfortunately I do not have a photo of that tube.


----------



## augustwest

Nice write-up! Extremely interesting reading.

 - augustwest


----------



## jamato8

I have a friend who worked for RCA and has multiple patents, though he was the inventer and RCA has the patent, on tubes. He designed and got the ball rolling on many tubes. I never thought to ask him about what he may know about the black and grey glass tubes but I will pose this to him. It is funny because many of the "new" circuits using tubes you read about and are brought forth as something just thought of are not. I have brought many of these designs to his attention and he always recognizes them.


----------



## augustwest

_"I have a friend who worked for RCA and has multiple patents, though he was the inventer and RCA has the patent, on tubes. He designed and got the ball rolling on many tubes. I never thought to ask him about what he may know about the black and grey glass tubes but I will pose this to him."_

 It would be great to document the real story from the "old timers" who made the tubes and find out why things were done a certain way. In both the manufacture and marketing methods used. I'm sure they just didn't use black/grey glass because it looked sexier.

 - augustwest


----------



## chat7

National Union (NU) gray glass 6SN7GT with rectangular top mica is the same with RCA grey glass which is the same as RCA VT-231


----------



## adhoc

Quote:


  Originally Posted by *chat7* /img/forum/go_quote.gif 
_National Union (NU) gray glass 6SN7GT with rectangular top mica is the same with RCA grey glass which is the same as RCA VT-231 
	

	
	
		
		

		
		
	


	


_

 

Look again - 

 There is no rectangular mica on a true NU grey glass. It is round. The mica spacers are also square, in contrast to the rectangular ones on both RCA variations.

 When you have enough experience with tubes you will realise that labels can mean nothing - I've seen tubes that were clearly RCA labeled NU.


----------



## sturob

Just a quick couple of questions on the RCA 6SN7GTA.

 I've got a single pair of these tubes which actually seem like a very nice 6SN7 variant. They have two side getters, directly opposite each other and at right angles to the plates (meaning, you can look at the flat side of the plates, but the gap between the plates if you're looking at the edge is obscured by the getters). Why two getters?

 Also, what's up with this tube? Seems like RCA made 6SN7GTs for quite a while, made the GTAs for a very short time, and then moved right into GTBs. Is my perception correct?

 Thanks,

 Stuart


----------



## adhoc

Quote:


  Originally Posted by *sturob* /img/forum/go_quote.gif 
_I've got a single pair of these tubes which actually seem like a very nice 6SN7 variant. They have two side getters, directly opposite each other and at right angles to the plates (meaning, you can look at the flat side of the plates, but the gap between the plates if you're looking at the edge is obscured by the getters). Why two getters?_

 

the question should be - why not? 
	

	
	
		
		

		
		
	


	




 Actually, no one outside of the engineers/designers behind that tube will likely know the answer to that question. I suppose the best answer for now would be: _because they can_.

  Quote:


  Originally Posted by *sturob* /img/forum/go_quote.gif 
_Ilso, what's up with this tube? Seems like RCA made 6SN7GTs for quite a while, made the GTAs for a very short time, and then moved right into GTBs. Is my perception correct?_

 

Yep - 100% correct. GTAs were never very popular and were quickly superceded by the better-rated GTB. My understanding is that GTAs took time to succeed the GT type (much like how leaded petrol was phased out in favour of unleaded), and by the time the phaseout of GT was complete, GTBs were already on the market. Kinda like how we all jumped from CD to VCD while leaving LD on the wayside.


----------



## sturob

Why not indeed. They look like a lot of work; I guess I'm not surprised the GTBs succeeded them so quickly. There seem to be a ton of Sylvania GTAs, but not so many RCA GTAs. Doing both of those getters, flashing both sides, blah blah, lots of extra time/expense if it's not "needed."

 They are a nice tube/valve, though. 

 Stuart


----------



## adhoc

Quote:


  Originally Posted by *sturob* /img/forum/go_quote.gif 
_Why not indeed. They look like a lot of work; I guess I'm not surprised the GTBs succeeded them so quickly. There seem to be a ton of Sylvania GTAs, but not so many RCA GTAs. Doing both of those getters, flashing both sides, blah blah, lots of extra time/expense if it's not "needed."

 They are a nice tube/valve, though. 

 Stuart_

 

I just realised that the tube you mentioned is not in my 'guide' - it would be great if you could drop me an email. If you would like to, please send it to the address listed in the first post. Thanks!


----------



## Glod

adhoc, this thread is really a great asset to this forum and anyone else interested in the 6SN7GT. Well done, thanks!

 I was wondering about your observations of the different filament alternatives, i.e. the 8SN7GT and 12SN7GT. Have you seen or heard of if these differ in construction to the 6,3V versions, besides the heater parts? 

 Interestingly, the Tungsram CV1988’s I have, have grey coating to the top mica, brown (micanol?) bases and black, staggered, ladder-ridged-flat-plates. The micas are racetrack formed, and the top one, with spikes at the round parts, touching the glass. Barely visible bottom getter. They are also stamped 6SN7GT (note not GTY).

 The base is without print, but the envelope is marked with the KB/T stamp with arrow, which means government ordered, approved, made to specification K1001 or K1006 and manufactured by Tungsram, Tottenham. 

 I’ll email you about the GEC B 65.


----------



## augustwest

It is my understanding, from my readings, that the RCA 6sn7's with the side getters, are actually made by GE. Do you know is that true?

 - augustwest


----------



## adhoc

Quote:


  Originally Posted by *augustwest* /img/forum/go_quote.gif 
_It is my understanding, from my readings, that the RCA 6sn7's with the side getters, are actually made by GE. Do you know is that true?

 - augustwest_

 

I am not certain as I only own 2 GTAs and both are GE. Have a look at the EIA codes on the tube - a 3 digit number should indicate the tube's 'true' manufacturer. 

 312 is Sylvania
 188 is GE
 274 is RCA

 and so on...


----------



## nikongod

hey, no triangle plate Sylvania 6sn7.

 actually, no triangle plate anything! 

 but they exist.


----------



## adhoc

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_hey, no triangle plate Sylvania 6sn7.

 actually, no triangle plate anything! 

 but they exist._

 

Got a photo?

 I'm thinking that _you _might be thinking of 'angled T plates' as 'triangle plates'.


----------



## augustwest

adhoc -

 I have a 6sn7 tube that I am hoping you might help me identify? It is a brown base, medium bottle with trianlular black plates. The only indentifing markings on it are "6sn7 / Tele - Rad" in small point type face. 

 - augustwest


----------



## adhoc

Quote:


  Originally Posted by *augustwest* /img/forum/go_quote.gif 
_adhoc -

 I have a 6sn7 tube that I am hoping you might help me identify? It is a brown base, medium bottle with trianlular black plates. The only indentifing markings on it are "6sn7 / Tele - Rad" in small point type face. 

 - augustwest_

 

A picture says a thousand words - send a picture to the email address in the first post.


----------



## adhoc

Quote:


  Originally Posted by *augustwest* /img/forum/go_quote.gif 
_adhoc -

 I have a 6sn7 tube that I am hoping you might help me identify? It is a brown base, medium bottle with trianlular black plates. The only indentifing markings on it are "6sn7 / Tele - Rad" in small point type face. 

 - augustwest_

 

Hope ya got my email. 
	

	
	
		
		

		
		
	


	




 If the spam filter ate it, it's almost certainly a Tungsol WGT or WGTA.


----------



## augustwest

_"If the spam filter ate it, it's almost certainly a Tungsol WGT or WGTA."_

 Thanks!

 - augustwest


----------



## Ocean7

Quote:


  Originally Posted by *adhoc* /img/forum/go_quote.gif 
_FEEL FREE TO POST REPLIES TO THIS THREAD!!!_

 

Well... thanks a million for this amazing amount of information. I bookmarked, and saved this page on my desktop. For a tube newbie like me, and new owner of a 336i this is definitely tremendous reading! Thank you, thank you, thank you!


----------



## Skylab

Quote:


 Who actually produced 5692s in the USA is a controversial issue amongst tube lovers; here are some of the competing theories:

 - All red base 5692s were made by RCA.
 - All red base 5692s were actually made by GE, but for RCA (explains the high incidence of GE labeled red bases).
 - All brown base 5692s were made by CBS-Hytron.
 - Raytheon made a brown base 5692.
 - Sylvania made a brown base 5692.
 - Westinghouse made a brown base 5692.

 [My opinion, based on personal experience, is that GE made red-based 5692s for RCA, and that CBS-Hytron (earlier) and Sylvania (later) made brown-based 5692s.] 
 

Just to make matters worse, I have a pair of red-base 5692's that are Sylvania branded 
	

	
	
		
		

		
			





 But here is the skinny on the 5692. The original 5692 was introduced by RCA in 1949. However, RCA red base 5692's were never manufactured by RCA, they were built under contract by General Electric, as the OP indicated. General Electric branded 5692 red base tubes are also quite common, and are identical of course to the RCA's, and as a side benefit generally sell for less oddly enough. I am almost 100% certain the Westinghouse branded ones are also GE made.

 CBS-Hytron, Sylvania, and Raytheon 5692's, as the OP surmised, are indeed NOT the GE tube. CBS-Hytron manufactured their own 5692, as did Raytheon and Sylvania. They look virtually identical to the RCA/GE except for the brown base (although there are some Sylvania Red Bases as well). Standard Electric of Sweden also made the 5692 usually labelled 33S30, and some consider it the best sounding, although it is almost impossible to find. 

 Many people, me included, feel the CBS/Hytron sounds better than the GE/RCA. I think it sounds MUCH better, actually.

 Later black-base tubes from RCA labeled 5692 are not really 5692's are are not good sounding tubes.


----------



## Spareribs

Great thread. I've been shopping around for some 6sn7 tubes on ebay have found some great prices for the vintage ones from the 40s and 50s. My prediction is that it will be even easier to find these 6sn7 tubes in the next few months or so with great bargain prices since the economy is slumping. 
 Just today, I got a World War II era Sylvania VT-231 for around $18.


----------



## jaydeecee

Spareribs;4897287 said:
			
		

> Great thread.
> 
> 
> 
> Does anyone know anything of the Tesla 6CC10 which is apparently a 6SN7?


----------



## Frihed89

Quote:


  Originally Posted by *Spareribs* /img/forum/go_quote.gif 
_Just today, I got a World War II era Sylvania VT-231 for around $18.




_

 

Check it. Does it have 3 holes in each plate. Is the top micah shiny and have three "fins"? Is there a lot of copper wiring down below the bottom micah.
 If so you have so called "Bad Boy" which is sonically the best of the early 6SN7GTs from the 50s, better than the WWII models.


----------



## Frihed89

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_hey, no triangle plate Sylvania 6sn7.

 actually, no triangle plate anything! 

 but they exist._

 

Tung-sol short bottle 6SN7GTBs have triangle plates.


----------



## Skylab

So do the later production Sylvania 6SN7WGT's.


----------



## tagosaku

For Sylvania/CBS I think Y-plate is nowhere near T-plate. 
 And in general T-plate seems better. I feel the same way about black plate vs. grey plate.


----------



## Skylab

Agree - the 40's and 50's Sylvania 6SN7WGT's are better than the ones from the 60's.


----------



## Spareribs

Quote:


  Originally Posted by *Frihed89* /img/forum/go_quote.gif 
_Check it. Does it have 3 holes in each plate. Is the top micah shiny and have three "fins"? Is there a lot of copper wiring down below the bottom micah.
 If so you have so called "Bad Boy" which is sonically the best of the early 6SN7GTs from the 50s, better than the WWII models._

 

It's got 2 holes. But I know what you are talking about. I also have the 3 hole '52 bad boys and they are great too. IMO, the 40's and the particular 50's 3 hole plates are both excellent tubes and worth having. I'm happy with either tube!


----------



## xchagg

I picked up a pair of TS round plates rebranded as Admiral from Ebay for cheap. ($28 shipped 
	

	
	
		
		

		
		
	


	




)
 They arrived dusty and dirty, but tested as NOS. After some cleaning up I plugged them into my DV336i. Thankfully there were no problems with either tube.

 It was my understanding that both Tung-Sol and rebranded/OEM round plate 6SN7s are the same tube, but I noticed a couple differences in construction:

 1. The black coating goes up nearer the top for the rebranded tubes.
 2. The rebranded tubes use steel? rods attached to the horseshoe-shaped plates, versus copper rods for the Tung-Sol branded tube.

 Pictures:

 Admiral rebranded TS-RP:





 TS-Branded:





 All 3 tubes:





 I cannot find a code on the TS branded tube, but the Admiral branded tubes both have a code of 322826.

 Does anyone know more details about the differences in construction between TS branded round plates and rebranded tubes. Are rebranded/OEM tubes constructed slightly differently, or are these tubes simply from different years of production?

 Sonically, I personally cannot differentiate between the tubes.

 Thanks!


----------



## Rob N

It does appear thet the Tungsol branded ones have copper posts whereas if the tube is branded differentely they don't

 On the left a TS round plate with round mica branded Tungsol (copper posts) on the right a round mica one branded RCA (no copper posts)






 Also a 12SN7GT labelled ForDom again no copper posts


----------



## Skylab

I'd say you got a smoking deal and would be grinning from ear tyo ear if I were you


----------



## Spareribs

For $28 it's a nice deal. Round Plates have gone for $499 a pair so for $28, it's not bad. My best 6sn7 deal was a pair of 50's GE military stock for just $20 and it turns out to be one of my favorite tubes. I also love it when tubes are rebranded like yours. You can get killer deals. I've seen NOS Dumont (Tungsol rebranded) rectifier tubes go for just $11 a pair.


----------



## xchagg

Ahh, so the different binding posts are present even on the round mica tubes. Interesting.

 At least now I know there are physical differences between TS-branded and rebranded round plates in other samples heh. Not physically identical tubes, but sonically identical to me at least. 

 And since both types edge out my previous favorite, a brown base Sylvania 6SN7 WGTA, no complaints from me, especially considering the price


----------



## Oskari

Glod, I know yours is an old message but I must ask something...

 I have this Mullard-branded 6SN7GT the manufacturer of which has been a mystery to me. See photo. It can't be Mullard-made because they apparently never made any 6SN7GTs.

 Then I found this photo on the natubes site. This Tungsram-branded 6SN7GT is exactly like my Mullard-branded one. Next I read this:

  Quote:


  Originally Posted by *Glod* /img/forum/go_quote.gif 
_Interestingly, the Tungsram CV1988’s I have, have grey coating to the top mica, brown (micanol?) bases and black, staggered, ladder-ridged-flat-plates. The micas are racetrack formed, and the top one, with spikes at the round parts, touching the glass. Barely visible bottom getter. They are also stamped 6SN7GT (note not GTY).

 The base is without print, but the envelope is marked with the KB/T stamp with arrow, which means government ordered, approved, made to specification K1001 or K1006 and manufactured by Tungsram, Tottenham._

 

Your description of the tube fits very well (except the base color). This makes me think that also my Mullard-branded tube was in fact made by British Tungsram, or the Tottenham factory when it wasn't owned by Tungsram anymore.

 What do you think? I'd be delighted to see a photo of one of your CV1988s with the KB/T stamp if you could provide one.


----------



## Skylab

Mullard did label tubes 6SN7GT and GTB for the export market. However, most of these were late in the tube game are clearly Russian-made (in spite of saying "Made in Britain" on them). Yours do not look Russian, however.


----------



## mourip

All of the sudden I am noticing information about NOS 1950's Russian 6H8C tubes, a 6SN7 sub, with very positive reviews and high prices. The well rated tube has specific plates and a nickle base. They are showing up on EBAY and someone is selling what looks like the same tube here on Head-Fi. Coincidentally the ad here and also one of the ads on EBAY quote the tube seller Jesse Brent as giving this tube high marks.

http://www.head-fi.org/forums/f44/fs...es-nos-409023/

Rare 6H8C Russian Military 6SN7GT Nickel Base Tubes NOS - eBay (item 170304968308 end time Mar-03-09 09:51:23 PST)


 Anyone tried this tube?

 Thanks,

 Paul


----------



## Skylab

There have been quite a few head-fiers who tried them and loved them I liked it fine but still prefer quite a few of the US and UK variants. 

 In any case ONLY the ones labeled 1578 are the good ones - they have a very unique plate structure. NEITHER the ones in the head-fi ad OR the Ebay ad you linked to are the right tube - those are just your typical Russian 6H8C with a nickel base are aren't worth $10. You can tell because they have the exact same plate structure as a normal 6H8C that you can buy on EBay for $5.

 This is the tube people rave about:

RARE! 1 USSR TUBE 1578=6SN7 Unique military development - eBay (item 250376900280 end time Feb-28-09 21:00:00 PST)


----------



## Oskari

Quote:


  Originally Posted by *Skylab* /img/forum/go_quote.gif 
_Mullard did label tubes 6SN7GT and GTB for the export market. However, most of these were late in the tube game are clearly Russian-made (in spite of saying "Made in Britain" on them). Yours do not look Russian, however._

 

They don't look Russian to me either.

 By the way, here is something that I haven't seen mentioned in this thread:

6SN7GT made by MBLE in Brussels (branded Miniwatt)

 This one has got a typical Philips group code between pins with L (=MBLE) factory code. Internally, this tube is quite like my Mullard-branded ones, but not an exact match.


----------



## glitch39

looks like GTA plates to me, probably a re-brand of a US made tube


----------



## Oskari

Quote:


  Originally Posted by *glitch39* /img/forum/go_quote.gif 
_looks like GTA plates to me, probably a re-brand of a US made tube_

 

Are you referring to my presumed MBLEs? I guess that is possible but I am not convinced. They have a proper code (r93 L1E) on them.


----------



## Black Stuart

Skylab is correct,
 I bought what were supposed to be 1578 tubes from Siberian tubes they are con artists don't buy from them.
 Greentulip/Ukraine is the man to buy from he is 100%. I have bought lots of 1578 from him. A dutch friend bought from him and one was dud, Greentulip replaced it ASAP.

 You either love them or only find them OK - I love them. IMHO they are excellant top to bottom, very dynamic, crystal clear, great edge definition without being hard in any way. I do have one criticism of this tube - they can be described as slighty dry, I intend to experiment with PIO coupling caps to counter this small (and I do mean small negative). In comparison I find other 6SN7s are very coloured I hav'nt tried SylWs or TS/RP so take that into account when reading my opinion.

 One huge point in their favour they are totally non-microphonic and you can't say that about a lot of 6SN7 tubes. In fact it is the least microphonic of any tube I have tried.


----------



## Frihed89

Contact Paul Lindeman AKA Chowbeardog on AA and he will set you up with the real deal. I have several pairs and am very satisfied with this tube. Mine were 100% NOS. The 1578 is a very well balanced tube with a lot of detail and a nice mid-range that is not entirely neutral. The bass is tight and low and the top end has a lot of extension and "sparkle" (not brightness). It combines some of the best elements of the TSRP and Sylvania 6SN7W.


----------



## mourip

Thanks for the replies on the 1578's. I have some Tungsol vt231's now and am always wondering what might be better


----------



## Black Stuart

Frihed89,
 I'd be interested in hearing in more detail about the mid-range 'not being entirely neutral'. Totally agree about the bass, it's the best I've ever heard in any signal valve/tube. I recently fitted some Z foils in my Bada and at first it's difficult to accept just how much detail is masked by inferior components. especially in the bass. 

 Today I tried a pair of 6F8G Tung Sol R/P s as o/put . If these are truly the same as Tung Sol RP 6SN7 then I have to say that the 1578s are much better in the bass than these but that is just first impressions and the bass may improve.

 If a really deep, expressive bass is important to you then these 1578s' are 'the business'.


----------



## applevalleyjoe

I have four Baldwin branded 6SN7GTB's which came off a Baldwin organ allegedly manufactured in 1960. They are new looking identical tubes with clear glass, straight sided walls, black bases, green lettering on the bases, chrome/silver tops, and rings shaped like halos at the top. No printing on the tubes themselves. They are each marked with a number (P28060-13C, P28060-25C et. al.) One of them has an additional number in very small letters: 6W6 or 9M9, depending on how you hold the bottle. Does anyone have an idea as to the manufacturer? I don't have a digital camera that's why I haven't posted a picture but all of the pertinent information is listed.


----------



## Skylab

IIRC, the vast majority of Baldwin branded tubes were Sylvanias.


----------



## glitch39

Quote:


  Originally Posted by *mourip* /img/forum/go_quote.gif 
_ I have some Tungsol vt231's now and am always wondering what might be better _

 

Find some loctal-octal adapters and use the 7N7. you can find some round plate 7N7's for cheap. exact 6SN7 equivalent on a different package


----------



## Frihed89

The NU 7N7 round plates are very, very fragile. Almost everyone i have talked with have had some problems. The T plates are very good and very rugged.


----------



## sedan delivery

Quote:


  Originally Posted by *mourip* /img/forum/go_quote.gif 
_All of the sudden I am noticing information about NOS 1950's Russian 6H8C tubes, a 6SN7 sub, with very positive reviews and high prices. The well rated tube has specific plates and a nickle base. They are showing up on EBAY and someone is selling what looks like the same tube here on Head-Fi. Coincidentally the ad here and also one of the ads on EBAY quote the tube seller Jesse Brent as giving this tube high marks.

http://www.head-fi.org/forums/f44/fs...es-nos-409023/

Rare 6H8C Russian Military 6SN7GT Nickel Base Tubes NOS - eBay (item 170304968308 end time Mar-03-09 09:51:23 PST)


 Anyone tried this tube?

 Thanks,

 Paul_

 

well,, I just finished reading this thread,and I'll be able to answer that question in a couple of days, as I bought a pair,, I hope they sound better than the chinese jobbies that are in my pre.I just got a Wright WLA 12,, we'll see. BTW,, this thread is fantastic,,and will be one of my "6SN7 reference" tube thread.Thanks to all who have contributed and educated me.


----------



## fallow81

Can you please help me with identification of this TungSol 6SN7 GT Tube ?
  Sorry - I have no change to do better pics now - I hope - you see something.
  Tube has writings: TUNG-SOL Made in U.S.A  and letter "P" (top line) code "3221-42" (bottom line)
  I know "332" is TungSol code. On the glass there is 6SN7 (top line) GT (bottom line) and "H1M" (probably) on the bottom of the sign.
  It has bottom "D" getter. Black "T"-plates. Construction is similar to VT-231 Sylvania included in photos also (on the bottom)
   
.
   
   
*Sylvania VT-231*


----------



## Skylab

322 is Tung-Sol's EIA Code
   
EIA Codes
   
  But that sure looks like a Sylvania Bad Boy to me, and it may well be,  I have a few Tung-Sol branded tubes that are clearly OEM'd from Sylvania.


----------



## fallow81

Quote: 





skylab said:


> 322 is Tung-Sol's EIA Code
> 
> EIA Codes
> 
> But that sure looks like a Sylvania Bad Boy to me, and it may well be,  I have a few Tung-Sol branded tubes that are clearly OEM'd from Sylvania.


 


  Thanks for the answer!
  I just found the difference - in my TungSol tube there is 3 holes in each plate, but in Sylvania VT-231 - from the photo -  2 holes. But I see in thanks to google,  Sylvanias Bad Boys with 3 holes also exists.


----------



## rosgr63

I would like to add another three 6SN7 European makers:
   
  ATES (Italy)
  Marconi Italiana (Italy)
  Philips (Italy)


----------



## mrAdrian

Hey tube masters! Got a challenge for you all...
   
  I got my first tube amp, a DV336i and the seller has kindly included some tubes for me. One of my 6sn7 is a RCA, which I might post pictures later. But today I want to know which variant is my Sylvania...
   
  Took some pictures for you masters. Please help..!!


----------



## koldby

The Marconi B65 is not always metal based.
  They can be , but are also made with black plastic base.
  Also with brown base and with smoked glass or clear glass.
  manufactored in Britten Holland USA .
   
  I have a few of these types )
  They are in my opinion the best of the 6sn7 types
  Koldby


----------



## i luvmusic 2

Very Nice


----------



## asindc

I need some assistance in identifying a tube.  I have a Cary SLP-05 that I need to re-tube.  I've already bought a mix of tubes to roll, but I figured I would try some of the tubes the seller of the 05 sent along with the preamp.  Of the two tubes in the first pic, I'm quite sure the tube on the left is the Sylvania 6SN7GT "Bad Boy."  It is described in the first post (by the way, excellent work, Adhoc.  Thank you.) as such:
  


> *Sylvania 6SN7GT 1952 “Bad Boy”*
> _Also JAN-CHS-6SN7GT
> Made only from late 1951 (‘1-48’ examples seen) to 1952. Differs slightly in construction from ‘regular’ Sylvania rectangular top mica 6SN7GTs. Re-labeled bad boys are known to exist._
> Base: black, green labels marked ‘2-XX’ (where XX is the week of the year)
> ...


 
  

  
 As seen in the next two pics, it is labeled "JAN-CHS 6SN7GT" and it is of 1952, week 3 vintage.
  

  

  
 The tube on the right in the first pic is the one I'm not sure about.  At first, I thought it was the Sylvania 6SN7GT, version 1, which is described as such in the first post:
  


> *Sylvania 6SN7GT version #1*
> _Also JAN-CHS-6SN7GT
> Identical to VT-231s except:
> - Green printing seen on black base; white labels are much rarer.
> ...


 
  
 As can be seen in the next two pics, this tube has three holes in the plates instead of two and the year date code is not underlined.  The production date is 1952, week 13.  It seems to match the description is every other way.  However, it also closely matches the description of the Bad Boy, except that it is slightly taller and has the lightning logo.
  

  

  
 I apologize for the sideways orientation of the pics.  Any thoughts as to what these tubes are will be appreciated.


----------



## i luvmusic 2

Hi,
   Anyone familiar with this site Westubes.com?Thanks!


----------



## Crashem

i luvmusic 2 said:


> Hi,
> 
> 
> Anyone familiar with this site Westubes.com?Thanks!




I am. What tube are you looking to buy from there?


----------



## i luvmusic 2

How do you test a tube for short without a tube tester is this possible?Thanks!


----------



## northendjazz

Looking for info CV1988's or rather factory codes. I have two marked [ JJ / JH ]  and [ CV1988 KB/T ] 6SN7GT with brown base, gray glass and staggered plates. Love how they sound in my rig just curious about which factory?


----------



## Oskari

T = British Tungsram, Tottenham
  
 See http://www.tubecollector.org/cv-valves.htm


----------



## northendjazz

Thanks for the useful link so T = British Tungsram, Tottenham. I'll add pics if useful.


----------



## Oskari

Pics are always nice.


----------



## MIKELAP

northendjazz said:


> Thanks for the useful link so T = British Tungsram, Tottenham. I'll add pics if useful.


----------



## northendjazz

Ok pics, I tried to see/photograph the getter? looks like two rods running side by side?


----------



## whirlwind

koldby said:


> The Marconi B65 is not always metal based.
> They can be , but are also made with black plastic base.
> Also with brown base and with smoked glass or clear glass.
> manufactored in Britten Holland USA .
> ...


 
 I have a B36....same tube , 12 volt version of B65, at least i think.......very nice tube.


----------



## CZ4A

Did DuMont ever manufacture their own 6SN7? I know they sourced some from Tung-Sol and I've read elsewhere they never made any receiving tubes. However, going through my tube stash I found this DuMont 6SN7GTB with DuMont's EIA number, 158.






I've seen a black plate version of this tube that looks identical otherwise on eBay. My question is, who made it?


----------



## Oskari

cz4a said:


> My question is, who made it?


 
  
 Not sure, but could be Toshiba.


----------



## Oskari

northendjazz said:


> Ok pics, I tried to see/photograph the getter? looks like two rods running side by side?


 
  
 Thanks! Your photos are impressive, doubly so considering the grey glass. The, assumably D, getter (holder), however, is not visible in your photos. It's hiding lower inside the bottle.


----------



## CZ4A

oskari said:


> Not sure, but could be Toshiba.




Then DuMont were lying liars that lied, because it says "USA" twice on this tube! You can see "Made in USA" under the DuMont label in the first picture, and here again with some kind of manufacturing code.

EDIT: I figured it out after some Google Image searching- it's a rebranded Raytheon.


----------



## Skylab

That would make sense, because wasn't a lot of the Toshiba tooling directly copied from Raytheon (on purpose under Raytheon's supervision)?


----------



## Oskari

skylab said:


> That would make sense, because wasn't a lot of the Toshiba tooling directly copied from Raytheon (on purpose under Raytheon's supervision)?




Hitachi was pretty close to Raytheon. Toshiba I don't know about.


----------



## Oskari

cz4a said:


> Then DuMont were lying liars that lied, because it says "USA" twice on this tube!




They wouldn't have been the first ones to do so.


----------



## Makiah S

So this is a pretty great thread! Very Resourcefull, but all the picture links are dead q.q


----------



## Digital Don

I found this article very helpful in understanding 6SN7 tubes. Much appreciated. Don


----------



## RoundRound

Hello People,
 Has anyone tried the *Sylvania CHS JAN 6SN7WGTA*? 66' - How does it sound?
  
 I found a matched quad for $150 - not sure if it's a good deal? I want to use them in the Freya...
  
 Thank you!


----------



## ThurstonX

Just started rolling 6SN7GTs in my Lyr, and have a question about the codes on the pair, below (6SN7GTAs).  The seller describes them as "angled plates," but I'm still trying to figure out all the different plate structures.  re: the codes, are they to be read vertically as two sets of numbers (my assumption), or horizontally as three sets of numbers?  Assuming vertically, "077" doesn't seem to refer to Sylvania, and I haven't any reference to it yet.  The "448" I'm guessing means the 48th week of 1954.  What about the "14B"(?) in the third photo?
  
 They've only been going about 24 hours, but digging them so far.  Tighter bass than the KEN-RAD and 3-hole Sylvania "Bad Boy" 6SN7GTs I rolled previously, and those weren't bad.  Early days, though.
  
 Thanks in advance for any info or insights.
  
  
*Photos pulled from eBay listing*


----------



## rnros

Yes, vertical read on the paint code. Yes, also on the '54 date for both base paint and top glass etch.
  
 And, I know you like these.  Don't overlook the GTBs of the mid to late '50s.


----------



## ThurstonX

rnros said:


> Yes, vertical read on the paint code. Yes, also on the '54 date for both base paint and top glass etch.
> 
> And, I know you like these.  Don't overlook the GTBs of the mid to late '50s.


 
  
 Thanks, Bob 
  
 I've got at least two pairs of GTBs, plus the two Fotons still to roll.


----------



## rnros

Sure. And, I know, above all else, you are thorough!
  
 Later I will send you some info on a 6C8G that I think is as good (or almost?) as the better 6SN7s I've heard in the Lyr.
 300mA heater so can be used in the Lyr2, or the MJ2 if you're thinking of going there.


----------



## Kryl0071

Hi
Do you have any ideas about data of year prodaction Sylvania 6sn7gtb?
I can read codes
 31
12
26
Also I have got RCA 6sn7gtb red print with code 63-35
Same question.


----------



## Oskari

kryl0071 said:


> Hi
> Do you have any ideas about data of year prodaction Sylvania 6sn7gtb?
> I can read codes
> 31
> ...




The way to read that is 312 126 where 312 is Sylvania and 126 is a YWW date. Since it's a GTB, 1951 is not possible. I'd bet on 1961. 26 could be the week, but it might mean second quarter as well.




kryl0071 said:


> Also I have got RCA 6sn7gtb red print with code 63-35
> Same question.




That should be YY-WW.


----------



## Kryl0071

Thanks a lot!!!


----------



## RoundRound

Guys,
 So just to clarify, if I have 6SN7 NOS tubes that are buzzing when used, there's no chance it will improve over time and the tubes are basically useless for audio?
 Is there a point cleaning the contact pins? And if so with what?
  
 Thank you,


----------



## whirlwind

roundround said:


> Guys,
> So just to clarify, if I have 6SN7 NOS tubes that are buzzing when used, there's no chance it will improve over time and the tubes are basically useless for audio?
> Is there a point cleaning the contact pins? And if so with what?
> 
> Thank you,


 
 Yes, they could improve...if these are older tubes, remember they may have been sitting on a shelf some where for years....give them some time to settle in.
  
 If the pins seem dirty, use some fine grit sand paper on them.


----------



## RoundRound

Thanks mate,
 How long will you give the tubes to improve?
  
 Also what about cleaning the pins with 95% alcohol?


----------



## ThurstonX

roundround said:


> Thanks mate,
> How long will you give the tubes to improve?
> 
> Also what about cleaning the pins with 95% alcohol?


 
  
 Assuming you mean isopropyl alcohol, that's fine.  I use 99% isopropyl + wood shaft cotton swabs, followed by DeoxIT Gold (from the Vacuum Tube Survival Kit).  I almost always clean some oxidation off the pins.  6SN7GTs usually take two swabs per tube, due to the pin size, I reckon.  Good luck with the crackle and buzz.  If they don't clear up after 100 hours, I'd be surprised if they ever do.  I have a pair of Siemens CCas I got for super cheap, one of which had that problem.  I gave it a few whacks with a pencil, which settled it down, ran it for a couple days, and the problem did not resurface.  YMMV.


----------



## RoundRound

thurstonx said:


> Assuming you mean isopropyl alcohol, that's fine.  I use 99% isopropyl + wood shaft cotton swabs, followed by DeoxIT Gold (from the Vacuum Tube Survival Kit).  I almost always clean some oxidation off the pins.  6SN7GTs usually take two swabs per tube, due to the pin size, I reckon.  Good luck with the crackle and buzz.  If they don't clear up after 100 hours, I'd be surprised if they ever do.  I have a pair of Siemens CCas I got for super cheap, one of which had that problem.  I gave it a few whacks with a pencil, which settled it down, ran it for a couple days, and the problem did not resurface.  YMMV.


 

 Thanks mate!
 What do you mean whack it with a pencil??


----------



## ThurstonX

roundround said:


> Thanks mate!
> What do you mean whack it with a pencil??


 
  
 OK, maybe "whack" is too strong a word.  Gently tap, tap, rap... in my experience that affects the crackle/buzz, and sometimes clears it up.  Sometimes the crackle/buzz will return.  Whaddaya gonna do.  Obviously you don't want to hit it so hard as to break the glass, but tube glass is pretty thick, at compared to a light bulb.  So, if you hear the crackle/buzz, give the glass a light tap and listen for a difference.  If it's only one tube, you'll need to know which tube feeds which channel (e.g., in the Schiit Lyr, Left is front, Right is rear).  Anyway, easy enough to tell when you start tapping.  Since this type of crackle/buzz is apparent without any audio playing, it's best if there is none.  Makes it easier to hear the effect.


----------



## RoundRound

thurstonx said:


> OK, maybe "whack" is too strong a word.  Gently tap, tap, rap... in my experience that affects the crackle/buzz, and sometimes clears it up.  Sometimes the crackle/buzz will return.  Whaddaya gonna do.  Obviously you don't want to hit it so hard as to break the glass, but tube glass is pretty thick, at compared to a light bulb.  So, if you hear the crackle/buzz, give the glass a light tap and listen for a difference.  If it's only one tube, you'll need to know which tube feeds which channel (e.g., in the Schiit Lyr, Left is front, Right is rear).  Anyway, easy enough to tell when you start tapping.  Since this type of crackle/buzz is apparent without any audio playing, it's best if there is none.  Makes it easier to hear the effect.


 

 Thank you,
 I'll give it a go!


----------



## ThurstonX

Just had to post this.  It's a world gone mad: http://www.ebay.com/itm/2-Tung-Sol-JAN-CTL-6SN7GT-round-plate-tubes-test-strong-balanced-tube-6SN7-amp/142285377649
  
 OTOH, I snagged a pair of black-glass KEN-RADs for $61


----------



## Kryl0071

Hi
RCA 6SN7GTB data code ML. Any ideas about Year of made?


----------



## Oskari

kryl0071 said:


> Hi
> RCA 6SN7GTB data code ML. Any ideas about Year of made?




Apparently that's a shipment date. October 1961.


----------



## Kryl0071

Thanks!


----------



## peter-a

I came across these Tung Sol 6sn7gt's and was wondering if anyone can tell me a bit more about these
What period? Same sound as mouse ear version?


----------



## eschell27

Hello, can anyone verify that this is considered a Sylvania 6SN7GT "bad boy" ?


----------



## brad1138

I am confused on tube readings when I am buying used. A popular tester gives results like 2500/2400  where 2600/2600 is typical new/best. I use to think it was 2400 out of 2500, but now I think those numbers are 2 different parts/aspects of the tube. Can anyone enlighten me on this?

Thank you.


----------



## CZ4A

brad1138 said:


> I am confused on tube readings when I am buying used. A popular tester gives results like 2500/2400  where 2600/2600 is typical new/best. I use to think it was 2400 out of 2500, but now I think those numbers are 2 different parts/aspects of the tube. Can anyone enlighten me on this?
> 
> Thank you.



Twin-triode tubes like 6SN7s are essentially the electrical elements of two triode tubes placed in one envelope. For example, the 6SN7 combines two 6J5 triodes (the electrical element) into one tube. If you look at this picture of a 6J5GT you'll see one plate structure in the glass while a 6SN7GT has two.







The 2500/2400 in your used example signifies that one triode has a transconductance rating of 2500 micromhos and the other triode is rating at 2400 micromhos. The typical new rating is 2600 micromhos for each triode.

There are other types of tubes that combine two to four dissimilar electrical elements into one envelope and those will have dissimilar new ratings. However, those types of tubes are uncommon in headphone amps.


----------



## brad1138 (May 2, 2017)

Thank you that makes sense, so how big of a deal is it when the number get far apart? like if you have a tube rated at 2500/2200 and 2600/2600 is "peak", is that tube "unbalanced"? Also, is there a reason 1 side would degrade faster than the other?


----------



## circatubes

peter-a said:


> I came across these Tung Sol 6sn7gt's and was wondering if anyone can tell me a bit more about these
> What period? Same sound as mouse ear version?


Those are Raytheon VT-231 era 6sn7gt , 1940's. 
Very nice tube.


----------



## circatubes

eschell27 said:


> Hello, can anyone verify that this is considered a Sylvania 6SN7GT "bad boy" ?


Yes.


----------



## circatubes

adhoc said:


> Quote:
> 
> 
> Originally Posted by *Frihed89* /img/forum/go_quote.gif
> ...



Nice post, To add, There was actually a scarce run of Bad Boys in 50'. black plates. 
Also grey plate 3- hole Bad Boys in 51' and maybe 52' if I remember correctly. 
I also have a tube with one 2-hole plate and one 3-hole plate, think 51' will check.


----------



## Kryl0071

Hi
Any idea about data of production Sylvania Gt vt-229?


----------



## winders

Kryl0071 said:


> Hi
> Any idea about data of production Sylvania Gt vt-229?



That's a 6SL7 tube.....


----------



## circatubes

brad1138 said:


> Thank you that makes sense, so how big of a deal is it when the number get far apart? like if you have a tube rated at 2500/2200 and 2600/2600 is "peak", is that tube "unbalanced"? Also, is there a reason 1 side would degrade faster than the other?





Kryl0071 said:


> Hi
> Any idea about data of production Sylvania Gt vt-229?


Just a labeled for the military 6sl7gt, prob 1941-45.


----------



## Kryl0071

Thank you! Is it a good idea to buy some?


----------



## circatubes

adhoc said:


> Quote:
> 
> 
> Originally Posted by *augustwest* /img/forum/go_quote.gif
> ...



Yes, have had many Tel-rad brown base tri black plate,  WGT*, all Tung-Sol


----------



## circatubes

Kryl0071 said:


> Thank you! Is it a good idea to buy some?


Yes,if you see them for a good price, grab em!


----------



## circatubes

Skylab said:


> Quote:
> 
> 
> Who actually produced 5692s in the USA is a controversial issue amongst tube lovers; here are some of the competing theories:
> ...




Wanted to share my opinion on the 5692's in general. I can't say I've listened critically to the CBS,but having listened to the GE/RCA extensively over the years, they
are not in my opinion, great sounding 6SN7 tubes, perhaps good in some systems. The experiences of my friends and customers who have tried many other tubes, seem to echo this.
The idea, the market seems to have that "long life" tubes, and this also goes for tubes in the 12A*7 family are better sounding and should be of greater value is a foolish one IMO.
Does a Prius outperform a Porsche? (telefunken ecc803S, weird sounding tube, not as good as a regular Tele ECC83, when I've heard it)
The 40's Grey Glass RCA 6SN7GT/231 is a better sounding tube than 5692.  Also, look out for the Pre-GTA clear glass RCA 6SN7GT, which is pretty much the same as the grey glass tube and should be very reasonable.


----------



## winders

circatubes,

What are your favorite 6SN7 tubes? Do you have a preference for the output buffer stage versus the gain stage? I am using a Schiit Audio Freya and people say that the output buffer stage tubes affect the sound less.

Thanks!


----------



## Mike Thompson

winders said:


> circatubes,
> 
> What are your favorite 6SN7 tubes? Do you have a preference for the output buffer stage versus the gain stage? I am using a Schiit Audio Freya and people say that the output buffer stage tubes affect the sound less.
> 
> Thanks!



It's been my experience that the tube on the buffer stage does effect the sound. I noticed a solid difference when I changed it from the stock tube to a Northern Electric 6SN7.


----------



## winders

Mike Thompson said:


> It's been my experience that the tube on the buffer stage does effect the sound. I noticed a solid difference when I changed it from the stock tube to a Northern Electric 6SN7.



Please note that I said "affect the sound less".


----------



## Mike Thompson

winders said:


> Please note that I said "affect the sound less".



Yes. It will have less of an impact then the gain side. I believe many people leave the original tubes on the buffer side.


----------



## attmci

Could someone please tell me who made these* "rare" Maroon/Brown Base* RCA 6SN7GT tubes?

http://www.ebay.com/itm/RARE-RCA-BR...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

http://www.ebay.com/itm/1-x-6SN7gt-...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

Sorry, this may had been discussed before.


----------



## winders

attmci said:


> Could someone please tell me who made these* "rare" Maroon/Brown Base* RCA 6SN7GT tubes?
> 
> http://www.ebay.com/itm/RARE-RCA-BROWN-BASE-6SN7GT-5692-VT-231-B65-VINTAGE-1950-039-S-USA-TUBES-TEST-NOS-/401321659545?hash=item5d70a28c99:g:wbQAAOSwBOtY9DyH&nma=true&si=TZzXlEbMoV3WXMFYIGv%2BklnztWU%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
> 
> ...



Everything is rare according to that "old_guy_radiola" seller. He regularly makes incorrect statements about tubes.


----------



## Skylab

attmci said:


> Could someone please tell me who made these* "rare" Maroon/Brown Base* RCA 6SN7GT tubes?
> 
> http://www.ebay.com/itm/RARE-RCA-BROWN-BASE-6SN7GT-5692-VT-231-B65-VINTAGE-1950-039-S-USA-TUBES-TEST-NOS-/401321659545?hash=item5d70a28c99:g:wbQAAOSwBOtY9DyH&nma=true&si=TZzXlEbMoV3WXMFYIGv%2BklnztWU%3D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557
> 
> ...



Is it a trick question? 

Anyway the answer is RCA made them.


----------



## circatubes

My favorite 6SN7's to listen to have been the Sylvania's: Bad Boy 3 -hole plate, 2 hole GT/231 black and grey plates, 6SN7W all versions. Tung Sol round plate and GTB.
Have found Ken Rad and RCA to be good in systems that veer towards overly analytical.


----------



## circatubes

Also, Raytheon GT/231 with "boxy" rectang plates , Raytheon T plate GT (sim to Sylvania GT) and CBS Hytron GT.


----------



## winders

Are these real "Bad Boys"?:


----------



## circatubes

Yes, one was relabeled by RCA or GE looks like. Has 52' glass code.


----------



## winders

circatubes said:


> Yes, one was relabeled by RCA or GE looks like. Has 52' glass code.



That tube on the left is labeled "S. R. L. INC." But I know that other names were put on Sylvania "Bad Boy" tubes so that doesn't bother me. The right tube is from the 13th week of 1953 which is still in the right date range for "Bad Boy" tubes. All the construction looks correct too. I just can't tell what kind of getter these tubes have.

I bought the pair for $120....


----------



## circatubes

winders said:


> That tube on the left is labeled "S. R. L. INC." But I know that other names were put on Sylvania "Bad Boy" tubes so that doesn't bother me. The right tube is from the 13th week of 1953 which is still in the right date range for "Bad Boy" tubes. All the construction looks correct too. I just can't tell what kind of getter these tubes have.
> 
> I bought the pair for $120....



Oh OK. the 4-52, looked like GE or maybe one of RCA's fonts. Have had them with all of those labels. SRL relabeled a lot of Tung Sol 
T plate variety and also Raytheon. 
Looks like a nice buy on a good used pair.  They look pretty nice from the pics.


----------



## winders

circatubes said:


> Oh OK. the 4-52, looked like GE or maybe one of RCA's fonts. Have had them with all of those labels. SRL relabeled a lot of Tung Sol
> T plate variety and also Raytheon.
> Looks like a nice buy on a good used pair.  They look pretty nice from the pics.



Thanks! If you do your homework sometimes you get rewarded with a great deal! I really wasn't looking to buy any more tubes for a while unless you had some of those Raytheon VT-231 tubes we talked about earlier. When I put my bid in with 10 seconds left it was under $100. Another bidder put in the same max amount I did after I did so I won.


----------



## whirlwind

winders said:


> Are these real "Bad Boys"?:



Yep, they sure are, construction is correct and the date codes match up.


----------



## attmci

winders said:


> Are these real "Bad Boys"?:



4-52, 1954 week 52. These are the real ones:

http://www.ebay.com/itm/SYLVANIA-BA...ad5fbb8&pid=100005&rk=5&rkt=6&sd=382079324617

Moreover,

THESE ARE PLATINUM MATCHED PAIR

LOL


----------



## winders

attmci said:


> 4-52, 1954 week 52. These are the real ones:
> 
> http://www.ebay.com/itm/SYLVANIA-BAD-BOYS-6SN7-GTA-Well-Balanced-Gm-Ip-PLATINUM-MATCHED-PAIR/141790603964?_trksid=p2047675.c100005.m1851&_trkparms=aid=222007&algo=SIM.MBE&ao=2&asc=41376&meid=9eb1dc6927ae42709709d8cbcad5fbb8&pid=100005&rk=5&rkt=6&sd=382079324617
> 
> ...



Yeah, those tubes are not "Bad Boys". No Sylvania 6SN7GTA is a "Bad Boy" and certainly no short bottle tube can be....


----------



## circatubes

Very sad. Anything to make a sale. what's scary is, it's a combination of BS
and ignorance out there. There are SOME good tube dealers on ebay, but there are people who sell
TONS of tubes who really have no idea or are 
full of it. Of course I'm completely biased, so don't listen to me  (Oh and shameless plug, those are actually nice sounding tubes, but I sell them for $50 pair)


----------



## winders

Does any know how to decode the date codes on Raytheon VT-231 tubes? I have 3 that have "CE5" and 1 that has "1E5" or "IE5".

Thanks!


----------



## winders

winders said:


> Does any know how to decode the date codes on Raytheon VT-231 tubes? I have 3 that have "CE5" and 1 that has "1E5" or "IE5".
> 
> Thanks!



Anyone? If not, does anyone have a suggestion on who might know?


----------



## circatubes

winders said:


> Anyone? If not, does anyone have a suggestion on who might know?



It's almost assuredly 1945. 
Probably March and September. 
6SN7GT's were labeled VT-231 mainly from 43-45.


----------



## winders

circatubes said:


> It's almost assuredly 1945.
> Probably March and September.
> 6SN7GT's were labeled VT-231 mainly from 43-45.



Thanks! So the "C" or "I" is the month and the "5" is the year. What is the "E"?


----------



## circatubes

Unsure. I think many or most had the E though. Never paid much attention to the Raytheon codes. 
Probably because they're less common tubes in the 231 stratosphere and they seemed to have been made later. I never thought about it until now and could be wrong but it seems as if they may have been the last major outfit to start making 6sn's.
I don't recall seeing any with codes before 43.  
and I think 44 & 45 is usually what I see.


----------



## attmci (Jun 25, 2017)

deleted.


----------



## winders

attmci said:


> But there are still good ones on the bay.
> 
> How about this tube?
> 
> http://www.ebay.com/itm/6SN7GT-Magnovox-Black-Plate-foil-Gett-Vacuum-Tested-84-100/263020219136?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2648



It's not a "Bad Boy". It has only two rivet holes in each plate.


----------



## attmci (Jun 25, 2017)

deleted.


----------



## winders

Regardless of what that site says and what Brent Jesse says, there are no such things as 2 hole "Bad Boys".

Look in this the first post of this thread:

https://www.head-fi.org/f/threads/the-reference-6sn7-thread.117677/

Find the section that starts with:

*Sylvania 6SN7GT (1952 vintage ONLY)
*
Only someone that wants to sell you something would say they are the same. Well, someone that is ignorant of the facts might say they are the same too.


----------



## attmci (Jun 25, 2017)

deleted.


----------



## winders

attmci said:


> Fine. No problem.



Hey, if you want to pay "Bad Boy" prices for inferior non-BAD Boy tubes, go for it. I was just trying to help you out with some information. I won't make that mistake again.....


----------



## circatubes

winders said:


> Regardless of what that site says and what Brent Jesse says, there are no such things as 2 hole "Bad Boys".
> 
> Look in this the first post of this thread:
> 
> ...




 From a few years back:
https://db.audioasylum.com/mhtml/m.....mpl?forum=ALL&searchtext=sherwood+s-7100a&r=


----------



## eagerears

Can somebody ID this tube? It's a Sylvania JAN-CHS-6SN7GT, but it doesn't exactly fit the descriptions at the beginning of this thread. I also can't figure out if those numbers on the back are a date code or not.




 

It's hard to see, but the front says "B 5" on the glass, if that helps.


----------



## circatubes

Looks like exactly what it says on the label. 
B5 indicates 1945.


----------



## eagerears

circatubes said:


> Looks like exactly what it says on the label.
> B5 indicates 1945.


I didn't phrase that question well. I did figure that it was a 6SN7, but I was wondering about the date of manufacture. Interesting that it's from 1945, it was sold as being from the 50's. Neat!


----------



## winders

eagerears said:


> I didn't phrase that question well. I did figure that it was a 6SN7, but I was wondering about the date of manufacture. Interesting that it's from 1945, it was sold as being from the 50's. Neat!



The "VT-231" designation was used only during WWII. It's an Army designation that stands for "Vacuum Tube 231".


----------



## mikewr

anyone know if a sylvania 6SN7GT HAS to have copper grid posts to be considered a true "bad boy". I'm looking at one that has all the specified criteria except for the copper grid posts and the numbers on the side read: 0 1 3, which mean it was made in 1950 correct?


----------



## Wildcatsare1

mikewr said:


> anyone know if a sylvania 6SN7GT HAS to have copper grid posts to be considered a true "bad boy". I'm looking at one that has all the specified criteria except for the copper grid posts and the numbers on the side read: 0 1 3, which mean it was made in 1950 correct?



I am definitely not an expert, but I think your date code is the first week of ‘53. I leave it to more knowledgeable folks to answer you other question.


----------



## circatubes

Well, I guess you'd really have to check with the Bad Boy Police to see if you were in compliance 
Yes, 1950. If you read the post I wrote on AAsylum, I mentioned copper grid posts.
The 1950 3 hole blackplate tube is a rare run, that seldom shows up, have had maybe 3-4 out of 100+ of the other years.
Some may have had non copper grids, I don't remember at this point. Had one last year,  I think.  The 2 - hole/VT-231 tube made from 41' or so to 51' with different labels used both copper and steel grid posts. The 44 & 45' tubes used both in the same year. It was just likely whatever was available while they were making their huge orders. Don't think it matters much , if at all as far as sound goes.
But never A/B'd posts..will have to give it a try. Wouldn't let the posts get in your way, all else being equal. Should sound very good. 



mikewr said:


> anyone know if a sylvania 6SN7GT HAS to have copper grid posts to be considered a true "bad boy". I'm looking at one that has all the specified criteria except for the copper grid posts and the numbers on the side read: 0 1 3, which mean it was made in 1950 correct?


----------



## mikewr

^thank you both for the info, appreciate it. Yes AAsylum is where I read about the copper grid posts lol. Just wanted to check up.


----------



## timb5881

Does any one know any thing about this Tung-Sol?  It has angled plates and a side getter.


----------



## RobertSM

Really fascinating reading here. What a storied history of a blue chip tube.


----------



## Wes S (Nov 30, 2018)

mikewr said:


> ^thank you both for the info, appreciate it. Yes AAsylum is where I read about the copper grid posts lol. Just wanted to check up.


All real Bad Boy tubes have copper grid post, and that is a big part of what makes it different from the steel post sylvania tubes.  Lots of wrong info out there.


----------



## Beestonite

adhoc said:


> *0. Introduction & preamble*
> 
> *[size=x-large]FEEL FREE TO POST REPLIES TO THIS THREAD!!![/size]*
> 
> ...


Hi there, what  a great  post, I am just awaiting  delivery  of my first  headphone  amplifier.  The darkvoice 336se,  but relating  to the 6sn7 tubes.  Do you know  if a brimar  6n7gt  is safe to use in this model. Please  note this is 6n7gt not the 6sn7 gt


----------



## bcowen

Beestonite said:


> Hi there, what  a great  post, I am just awaiting  delivery  of my first  headphone  amplifier.  The darkvoice 336se,  but relating  to the 6sn7 tubes.  Do you know  if a brimar  6n7gt  is safe to use in this model. Please  note this is 6n7gt not the 6sn7 gt



The Darkvoice 336se uses a 6N8P natively which is similar to a 6SN7. The 6N7 has a different pinout than the 6SN7, so an adapter would be required at minimum. The 6N7 also draws much higher heater current than the 6SN7 (or 6N8P), so even with an adapter it may be very risky to use depending on the max current the DV can handle safely.


----------



## Beestonite

bcowen said:


> The Darkvoice 336se uses a 6N8P natively which is similar to a 6SN7. The 6N7 has a different pinout than the 6SN7, so an adapter would be required at minimum. The 6N7 also draws much higher heater current than the 6SN7 (or 6N8P), so even with an adapter it may be very risky to use depending on the max current the DV can handle safely.


                Thank  you very  much for that information,  you may just have saved  me a lot of problems.


----------



## adhoc

I came out of retirement to say that unless a 6n7 is specified by your amp manufacturer as a drop in replacement for a 6sn7 (highly unlikely), it is NOT compatible.

It's operating characteristics are different, and as mentioned above it's pin configuration is different..


----------



## bcowen

adhoc said:


> I came out of retirement to say that unless a 6n7 is specified by your amp manufacturer as a drop in replacement for a 6sn7 (highly unlikely), it is NOT compatible.
> 
> It's operating characteristics are different, and as mentioned above it's pin configuration is different..



Retirement?  I want that job. Where do you get an application?


----------



## Beestonite

adhoc said:


> I came out of retirement to say that unless a 6n7 is specified by your amp manufacturer as a drop in replacement for a 6sn7 (highly unlikely), it is NOT compatible.
> 
> It's operating characteristics are different, and as mentioned above it's pin configuration is different..


Thank you for coming  out of retirement  to help  out  a newbie . Any contributions  and recommendations  are always  appreciated.


----------



## ScubaMan2017

adhoc said:


> I came out of retirement to say that unless a 6n7 is specified by your amp manufacturer as a drop in replacement for a 6sn7 (highly unlikely), it is NOT compatible.
> 
> It's operating characteristics are different, and as mentioned above it's pin configuration is different..


Newcomers like us appreciate you surfacing and giving us fair warning about just plopping any-old tube into our gear. This thread, while old, is still used by us. Thanks, @adhoc  .


----------



## sennfan83261

Can anyone help me id the year of this Sylvania 6SN7GT (date codes: 939 and J8A)?  I thought it was 1959, but then I read somewhere that 6SN7GT's were already phased out by then.  Also, is there a guide for lettered date codes for Sylvania tubes?  I found a reference guide for RCA tubes but came up empty for Sylvania tubes.  Thanks!


----------



## Ripper2860 (Jul 23, 2019)

The code on the base seems to indicate 1949 (39th week).  The 8 on the top J8A code seems to indicate 1948 tube MFG.  The thing about tubes is the glass envelopes are mfg separately from the base and sometimes are not mated to a base until a later time.  Sometimes the labeling on the base does not even match the tube markings (ex: I have a 6SN7W in a 6SN7GT base).  Your's seems to be a tube made in 1948 and mounted to a base in 1949. Some believe the top J is a factory code, but there does not really seem to be a consensus.  Seems like they stopped etching top tube codes after the 40's as all my Sylvies with top tube codes are from the 40's.


----------



## cddc

subscribed


----------



## jambaj0e

So I just got these Ken-rad vt-231 black glass tube for my Schiit Lyr 3 hybrid tube amp, except it doesn't say Vt-231 anywhere. It seems to have the typical physical attributes of this tube based on head-fi's 6SN7 Identification guide thread (Black glass, black flat plates with ladder riding, rectanglular mics with 3 spikes and line of small holes down the middle of the mica).

What do you guys think? Did I get screwed on this, or is this non-vt-231 sound the same as the Vt-231?

My system is USB audio to Chord MOJO Dac to Schiit Lyr 3 hybrid tube Amp to Audeze LCD-2C.


----------



## Old Deaf Donkey (Aug 26, 2019)

It is a Ken-Rad made tube, from the top mica, and the plates are staggered. As for the rest - if it sounds great to you, that's alright , if not - well. IMHO nothing in the tube's looks gives a 100% guarantee of good sound. I have two identical structure KR 6C8G, both measure well on a tester, and one starts sounding like crap on higher load, whilst the other sounds divine. Go figure.


----------



## jambaj0e (Aug 26, 2019)

Old Deaf Donkey said:


> It is a Ken-Rad made tube, from the top mica, and the plates are staggered. As for the rest - if it sounds great to you, that's alright , if not - well. IMHO nothing in the tube's looks gives a 100% guarantee of good sound. I have two identical structure KR 6C8G, both measure well on a tester, and one starts sounding like crap on higher load, whilst the other sounds divine. Go figure.



Well it does sound great, actually, especially the smooth mids. The numbers on the side, what do they refer to? It says in a vertical line "P 4 R" to the left of Kenrad, and "M-R" to the right of Kenrad.


----------



## Old Deaf Donkey (Aug 26, 2019)

jambaj0e said:


> Well it does sound great, actually, especially the smooth mids. The numbers on the side, what do they refer to? It says in a vertical line "P 4 R" to the left of Kenrad, and "M-R" to the right of Kenrad.


As I recall, P would be April (second set of month numbering starting from L, O and Q omitted not to confuse with 0) and 4 1944. No idea about the rest.


----------



## jambaj0e

UPDATE: So TCtubes.com acknowledge that the tube listing was mislabeled as VT-231 and gave me a discount of $15. Now that's what I called really good customer service. I'm probably going to stick with this KenRad, especially since it doesn't have the buzzing, microphonics , or any other issues that I read that some of the Kenrad Black Glass may have. 

Thank TCTubes! =D


----------



## attmci

jambaj0e said:


> So I just got these Ken-rad vt-231 black glass tube for my Schiit Lyr 3 hybrid tube amp, except it doesn't say Vt-231 anywhere. It seems to have the typical physical attributes of this tube based on head-fi's 6SN7 Identification guide thread (Black glass, black flat plates with ladder riding, rectanglular mics with 3 spikes and line of small holes down the middle of the mica).
> 
> What do you guys think? Did I get screwed on this, or is this non-vt-231 sound the same as the Vt-231?
> 
> My system is USB audio to Chord MOJO Dac to Schiit Lyr 3 hybrid tube Amp to Audeze LCD-2C.


These are authentic Kentucky-Radio according to the structure.


----------



## jambaj0e (Sep 1, 2019)

Tube rolling time! I just got this Sylvania 6SN7GT tube, and the seller says it is the Bad Boys 3-rivet, but from 1950.

So far it sounds good, even cleaner sounding than my Kenrad 6SN7GT Black Glass, but with just about the same bass, give or take, possibly not as low of an extension, but the same rumble. It may sound slightly more forward, slightly less sound stage.

Can someone verify that this is the Sylvania Bad Boy? What's the fuzzyness at the top of the glass? Anything to worry about? It says "039" vertically down the side of the black part


----------



## jambaj0e

So my Sylvania "Bad Boy" has the triangle Sylvania logo and "0 3 9" typed vertically to its right.

Here is how it looks from top, as well.


----------



## Ripper2860 (Aug 31, 2019)

Has all of the characteristics of a 3HBB and it's within the date range.

Enjoy!


----------



## jambaj0e

Ripper2860 said:


> Has all of the characteristics of a 3HBB and it's within the date range.
> 
> Enjoy!



I always thought it's supposed to be the 1952, but so far so good. Should I worry about that fuzzy circular marks at the top of the glass?


----------



## Ripper2860 (Aug 31, 2019)

Technically, it really is not in the date range if you go by the base code.   The date range is late 51, all of 52, and early 53.

I wouldn't necessarily get hung up on the base date code if the tube structure is correct.  Tubes and bases are mfg'ed separately.  There are quite a few cases where the tube was mated to a base that did not match.  They may have had a bunch of 50s bases available and mounted the tube to what they had onhand.

Ex: I have a Sylvania 6SN7W etched tube mated to a 6SN7GT base.


----------



## Old Deaf Donkey

jambaj0e said:


> I always thought it's supposed to be the 1952, but so far so good. Should I worry about that fuzzy circular marks at the top of the glass?


The marks are left by the heaters working. They just show that a tube has been used. I do not know if one can judge by these burn marks how much tube life is left. Tube tester shows better, IMHO.


----------



## bcowen

jambaj0e said:


> I always thought it's supposed to be the 1952, but so far so good. Should I worry about that fuzzy circular marks at the top of the glass?



If the marks are brown, then it is a sign of usage as ODD stated. If they are silver, it's excess getter material and is not a reliable indicator of usage.


----------



## jambaj0e

Ooh, there really is something nice about these Sylvania Bad Boys. I may even like them more than the Kenrad Black Glass since the mid-treble is a bit more opened up, and I can still get the same bass impact and soundstage as the Kenrad.

I do notice clearer resolution and less veiling in the Bad Boys, which helps since I've EQ'd up the bass for the Audeze and that still hits hard, but I don't lose as much in the mids/trebles as I did with the Kenrad.

This may be the better pairing for the already somewhat darker Audeze, too.


----------



## adhoc

jambaj0e said:


> Tube rolling time! I just got this Sylvania 6SN7GT tube, and the seller says it is the Bad Boys 3-rivet, but from 1950.
> 
> So far it sounds good, even cleaner sounding than my Kenrad 6SN7GT Black Glass, but with just about the same bass, give or take, possibly not as low of an extension, but the same rumble. It may sound slightly more forward, slightly less sound stage.
> 
> Can someone verify that this is the Sylvania Bad Boy? What's the fuzzyness at the top of the glass? Anything to worry about? It says "039" vertically down the side of the black part


Yes, that looks like the Bad Boy.

The "fuzziness" you see up top is deposited evaporated metal from the cathode heater element - similar to how water will condense on a cool window next to a boiling kettle. It doesn't affect tube functionality, but is an indication that the tube has been used before for at least a double digit number of hours.


----------



## attmci

adhoc said:


> Yes, that looks like the Bad Boy.
> 
> The "fuzziness" you see up top is deposited evaporated metal from the cathode heater element - similar to how water will condense on a cool window next to a boiling kettle. It doesn't affect tube functionality, but is an indication that the tube has been used before for at least a double digit number of hours.


Double-digit is a very conservative guessing.


----------



## jambaj0e

adhoc said:


> Yes, that looks like the Bad Boy.
> 
> The "fuzziness" you see up top is deposited evaporated metal from the cathode heater element - similar to how water will condense on a cool window next to a boiling kettle. It doesn't affect tube functionality, but is an indication that the tube has been used before for at least a double digit number of hours.





attmci said:


> Double-digit is a very conservative guessing.



This is what is said on the Ebay auction page for it:



*Rare 1950 3 rivet Sylvania 6SN7GT black plate "Bad Boy".*

*Rare first run, 1950 C0M on glass and 039 on base. 95% + of these are from late 51' to early 53'*

*Excellent Sound!! Listening tested in a preamp and Maxi-preamp noise tester for noise and low microphonics.*

*Test @ 2650/3000 where 1640 is min good for gm on a calibrated Hickok 539B.  *


----------



## attmci

jambaj0e said:


> This is what is said on the Ebay auction page for it:
> 
> 
> 
> ...


No worries, just enjoy the music. It's a nice tube still at very reasonable price.

https://www.ebay.com/itm/1-X-Sylvania-6SN7-GT-Vacuum-Tube-Tested/273989799875?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649


----------



## JKDJedi (Sep 9, 2019)

I think you guys took it easy on him...lol, I gave him hell on Facebook about it (Bad Boy). So if it looks and smells like a Bad Boy ...it's a Bad Boy, regardless of date. ( SMH ) anyway, a good buy, and seems to be a keeper. Enjoy.  (whatever happened to THE GOOD BOY talk)?


----------



## jambaj0e

JKDJedi said:


> I think you guys took it easy on him...lol, I gave him hell on Facebook about it (Bad Boy). So if it looks and smells like a Bad Boy ...it's a Bad Boy, regardless of date. ( SMH ) anyway, a good buy, and seems to be a keeper. Enjoy.  (whatever happened to THE GOOD BOY talk)?



Thanks man, and I definitely have been enjoying this "bad boy" tube. It is more musical and has a larger soundstage than the Ken Rad Black Glass that I got before this one. This one's a keeper (until I find an actual 1952 3-hole Bad Boy that is, lol)


----------



## Wes S

Other than the Brimar CV1988, the real "Bad Boy", was my favorite tube in the Lyr 3, when I owned it.  The Bad Boy, is linear, yet exciting and smooth.  The Brimar, takes all that one step further, and expands the sound stage.


----------



## JKDJedi

Wes S said:


> Other than the Brimar CV1988, the real "Bad Boy", was my favorite tube in the Lyr 3, when I owned it.  The Bad Boy, is linear, yet exciting and smooth.  The Brimar, takes all that one step further, and expands the sound stage.


$600 for a pair much?  https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/264446006927


----------



## Wes S

JKDJedi said:


> $600 for a pair much?  https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/264446006927


Yep!  That is quite a bit more than I paid for mine.  They can be found for around $200 a pair, or $100 to $150 a single, and are worth every penny.


----------



## JKDJedi

Wes S said:


> Yep!  That is quite a bit more than I paid for mine.  They can be found for around $200 a pair, or $100 to $150 a single, and are worth every penny.


I'd grab one real quick for $100.. seen them go for $200 last time searching for that tube. Great reviews on it.


----------



## attmci (Sep 16, 2019)

JKDJedi said:


> I'd grab one real quick for $100.. seen them go for $200 last time searching for that tube. Great reviews on it.


Not worth $100. YMMV.

https://www.head-fi.org/threads/fs-brimar-6sn7-cv1988-used.911173/


----------



## JKDJedi

And I pulled the plug on the Bad Boys ..thanks JambaJoe ... The pair seems to be the Real Deal Holyfield. Sylvania JAN-CHS 6SN7GT 1952.


----------



## jambaj0e

JKDJedi said:


> $600 for a pair much?  https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/264446006927



Whoa! Those are expensive tubes! Must be amazing to own those


----------



## toufeeq

Anyone know if this one is a legit TS 6SN7GT? https://www.ebay.com/itm/Mickey-Mou...tem4d9efdb4a7:g:OwsAAOSwwKNduSZT&LH_Auction=1


----------



## RobertSM

toufeeq said:


> Anyone know if this one is a legit TS 6SN7GT? https://www.ebay.com/itm/Mickey-Mouse-Ears-Tung-Sol-6SN7GT-Tested-see-text-Very-good-condition/333379908775?hash=item4d9efdb4a7:g:OwsAAOSwwKNduSZT&LH_Auction=1



I also saw this listing auction earlier. I can't say for sure if it's the real McCoy. I'd pass. But YMMV.


----------



## Monsterzero

toufeeq said:


> Anyone know if this one is a legit TS 6SN7GT? https://www.ebay.com/itm/Mickey-Mouse-Ears-Tung-Sol-6SN7GT-Tested-see-text-Very-good-condition/333379908775?hash=item4d9efdb4a7:g:OwsAAOSwwKNduSZT&LH_Auction=1



Yes its legit. Tung sol was the only company to make the Mouse Ears. FWIW I dont think its all that special sounding to be honest,but for 5 bucks what the heck.


----------



## toufeeq

Monsterzero said:


> Yes its legit. Tung sol was the only company to make the Mouse Ears. FWIW I dont think its all that special sounding to be honest,but for 5 bucks what the heck.


 Yeah, the mouse ears kinda convinced me. It would be really hard to fake them. I think the print has been wiped out from the base.


----------



## cebuboy (Nov 15, 2019)

Fotons from left to right: ‘52, ‘56, ‘65

early ‘50s have a metal tab in the bottom mica and the plates are ribbed.

late ‘50s no tab, still ribbed plates.

‘60s have smooth plates.

after the sixties, there are no top mica supports.


----------



## RobertSM

cebuboy said:


> Fotons from left to right: ‘52, ‘56, ‘65
> 
> early ‘50s have a metal tab in the bottom mica and the plates are ribbed.
> 
> ...



Sound impressions? I'm looking for other options for my tube phono preamp that uses a 6SN7 as a cathode follower in the circuit.  Thank you.


----------



## cebuboy

RobertSM said:


> Sound impressions? I'm looking for other options for my tube phono preamp that uses a 6SN7 as a cathode follower in the circuit.  Thank you.



They are very good for the price, the sound is lively with good detail and slam from a Lyr 3. The early ‘50s sound almost the same, while the ‘60s loose some of that slam and clarity.


----------



## bcowen

cebuboy said:


> Fotons from left to right: ‘52, ‘56, ‘65
> 
> early ‘50s have a metal tab in the bottom mica and the plates are ribbed.
> 
> ...



'56 was the last year of the ribbed plate. Starting in '57, the plates went smooth.  To my ears, any of the '50's are noticeably better than anything from the '60's or later.  Most of them need to have the pins resoldered though...


----------



## RobertSM

Looking for some help identifying what exactly I have here.

The text on the base says GE for CGE. I've done a little bit of research and believe that CGE is Canadian General Electric. But not sure. 

The tubes are tall, plates are dark grey, maybe even black depending on the lights. Plates are large and they seem to have copper rods running through. Maybe acting for support? 

Markings on the bottle say 6SN7GTB

Any and all help would be greatly appreciated.  Thank you.


----------



## bcowen

RobertSM said:


> Looking for some help identifying what exactly I have here.
> 
> The text on the base says GE for CGE. I've done a little bit of research and believe that CGE is Canadian General Electric. But not sure.
> 
> ...



The lack of etched dots in the glass means it likely (but not positively) wasn't made by GE, which is fortunate.   Here's the closest thing I have to it. Many similarities, although there are more (and longer) spikes on the mica ends with your tube:






:


----------



## RobertSM

Thanks @bcowen 

I've found a Westinghouse 6sn7gtb online that looks similar to what I have. It does get confusing with all the rebranding that goes on for sure.


----------



## bcowen

RobertSM said:


> Thanks @bcowen
> 
> I've found a Westinghouse 6sn7gtb online that looks similar to what I have. It does get confusing with all the rebranding that goes on for sure.



Yes, it is quite similar to the desirable Westinghouse D-Getter...just with an O getter. Some have reported that the sonic difference between the D getter and O getter versions are negligible (if even different at all), so you might have a really nice sounding tube there!


----------



## RobertSM (Apr 20, 2020)

bcowen said:


> Yes, it is quite similar to the desirable Westinghouse D-Getter...just with an O getter. Some have reported that the sonic difference between the D getter and O getter versions are negligible (if even different at all), so you might have a really nice sounding tube there!



So I bid and won this lot of tubes from a Canadian gentleman on Ebay. He was a old time audiophile who was getting up in years and wanted to get rid of what he had.

I've tried to contact him after the fact to see if I could get some information but he's just disappeared.

There was a bunch of Rogers 12ax7s. These 2 6sn7gtbs. A few other tubes too. I've had this box for at least the last 8-9 months but now with time to finally look into seeing what everything is.


----------



## bcowen

RobertSM said:


> So I bid and won this lot of tubes from a Canadian gentleman on Ebay. He was a old time audiophile who was getting up in years and wanted to get rid of what he had.
> 
> I've tried to contact him after the fact to see if I could get some information but he's just disappeared.
> 
> There was a bunch on Rogers 12ax7s. These 2 6sn7gtbs. A few other tubes too. I've had this box for at least the last 8-9 months but now with time to finally look into seeing what everything is.



I looked at the D-Getter WH's I have, and strangely enough the micas are closer to the Raytheon than your tube -- fewer and shorter points. Of course minor variations like that could be just different manufacturing years. And who knows...maybe Raytheon made all the Westinghouses we're talking about....or vice versa.


----------



## RobertSM

@bcowen 

Sonically speaking do the Raytheons and Westinghouse 6sn7gtb have similarities?

I'm wondering how my pair of tubes may sound and how to use them in a circuit that allows them to shine and show off their best traits. Just as I write this I'm wondering if they may play nicely in a tube headphone amp I have that uses a 12ax7 as an input tube and then uses a pair of 6sn7s on the output. Ultimately, I'll just have to try them out.


----------



## bcowen

RobertSM said:


> @bcowen
> 
> Sonically speaking do the Raytheons and Westinghouse 6sn7gtb have similarities?
> 
> I'm wondering how my pair of tubes may sound and how to use them in a circuit that allows them to shine and show off their best traits. Just as I write this I'm wondering if they may play nicely in a tube headphone amp I have that uses a 12ax7 as an input tube and then uses a pair of 6sn7s on the output. Ultimately, I'll just have to try them out.



I haven't ever compared them. I don't know that I've ever even listened to the Raytheon, honestly.  Too Many Tubes syndrome. Normally that's a positive thing. 

Interestingly, when it comes to the Raytheon 6SN7GT / VT231, I much prefer the T-plate version on the left to the flat plate version on the right that I find rather bright and screechy. Entirely different construction from your tube though, so doesn't have much bearing beyond just the comment.


----------



## Ranger Ron

RobertSM said:


> Looking for some help identifying what exactly I have here.
> 
> The text on the base says GE for CGE. I've done a little bit of research and believe that CGE is Canadian General Electric. But not sure.
> 
> ...


Hello Robert, new member here. I've loved reading and learning from everyone here. Have you considered the idea of these two tubes being of Japanese origin? Hitachi or Toshiba?


----------



## RobertSM

@Ranger Ron-

I had somewhat put the hunt and answer to this question aside. 

But now that your mention this possibility I'll have to look into it. For what it's worth I think "Made in Japan" circa 1970'-1980's still gets a bad rap. But as we know in relation to Hi-Fi they are now calling this the "Golden age of Hi-Fi". I don't have any personal experience with Japanese made tubes...yet. Well, maybe I do, maybe if I learn these tubes are Japanese made.

The tubes themselves are actually very good. They have a balanced frequency spectrum with great bass extension. They do offer up a warm sweet presentation, which I favor. The only hit on them, is that they can get a little shouty on the very high notes, usually with female vocals. It's just a small issue for me. I overall really like them. 

Thanks again for opening my mind to this possibility. It's one of the reasons I really value this community. People like yourself offering thoughts on the fun subject of Hi-Fi/Head-Fi/audio


----------



## MarkusTubesNow

RobertSM said:


> they can get a little shouty on the very high notes, usually with female vocals.



Well, consider that they might need to burn in for a while. That could affect the "shouty" characteristic.


----------



## Ranger Ron

MarkusTubesNow said:


> Well, consider that they might need to burn in for a while. That could affect the "shouty" characteristic.





RobertSM said:


> @Ranger Ron-
> 
> I had somewhat put the hunt and answer to this question aside.
> 
> ...


Robert, absolutely. I have a few different tube types from Japan that I am very pleased with. In fact one in particular just stunned me. I could not believe how wonderful and smooth it sounded compared to some other pretty high end brand names in that specific circuit slot.  As they say, enjoy the roll


----------



## MarkusTubesNow

Ranger Ron said:


> I have a few different tube types from Japan that I am very pleased with. In fact one in particular just stunned me. I could not believe how wonderful and smooth it sounded compared to some other pretty high end brand names in that specific circuit slot


 
By any chance is this in a preamp circuit? And what brand is it? What vintage, physical description, etc? Come on, man. Let us have a little info here...


----------



## Ranger Ron

MarkusTubesNow said:


> By any chance is this in a preamp circuit? And what brand is it? What vintage, physical description, etc? Come on, man. Let us have a little info here...
> 
> Ha! It's not a 6sn7 so I didn't want to get into it on this thread. It's a 12ax7A long grey plate I believe made by toshiba. Flat foil plate like getter with one dimple in the middle. Copper grid posts.


----------



## Ranger Ron

Yes preamp tube first slot in a decware phono pre


----------



## Painterspal

I’d welcome some feedback on this tube which as you can see is stated as a Sylvania JAN 6SN7 WGTA but doesn’t seem to match the description which suggests it should have a brown base, top getter etc. To me it looks more like a Sylvania 6SN7GT of the so called “Bad Boy” type.


----------



## Ripper2860

Looks like a Bad Boy to me.  3-hole plates and top mica has 3 points on short side with the points slightly pointing downward.  IIRC, 3H BBs ran from late 51 to early 53 and this appears to have 1953, 10th week markings.


----------



## Painterspal

Ripper2860 said:


> Looks like a Bad Boy to me.  3-hole plates and top mica has 3 points on short side with the points slightly pointing downward.  IIRC, 3H BBs ran from late 51 to early 53 and this appears to have 1953, 10th week markings.



Thanks, much appreciated. I hoped it was - it certainly sounds like it might be the real deal.


----------



## bcowen

Painterspal said:


> Thanks, much appreciated. I hoped it was - it certainly sounds like it might be the real deal.



Not to derail your question here, but what is the tube beside it? European obviously, but is it an output tube or a rectifier?


----------



## Painterspal

bcowen said:


> Not to derail your question here, but what is the tube beside it? European obviously, but is it an output tube or a rectifier?


It’s an A1834 - a 6AS7G type - probably made by GEC in the UK.


----------



## bcowen

Painterspal said:


> It’s an A1834 - a 6AS7G type - probably made by GEC in the UK.



Sweet!  And here I was thinking a Western Electric 421A was expensive.


----------



## Painterspal

bcowen said:


> Sweet!  And here I was thinking a Western Electric 421A was expensive.


I got lucky, it came with the amp so I didn't pay the going rate.


----------



## Kryl0071

Hi
Sylvania 6sn7GTB CODE 909 AKZ. Any ideas year of production?


----------



## Ranger Ron

Kryl0071 said:


> Hi
> Sylvania 6sn7GTB CODE 909 AKZ. Any ideas year of production?


1959 most likely


----------



## Kryl0071

Thanks!


----------



## cddc (Oct 16, 2020)

9th week of 1959


----------



## hackstu

seen this tube on langrex, 1952 rca 6sn7gt bottom getter. Is this the bottom d getter version? What would be good test values


----------



## TnTMaN

Can someone confirm that these are the holy grail   Sylvania 6SN7A ?  The top actually does have very faint print of 6SN7A .. how much would this matched pair be worth?


----------



## highstream (Aug 15, 2020)

Came across a pair from legitimate seller that are advertised as CBS 6SN7GT, two hole bad boy black plate D GETR testing as NOS 1955, but black bases say Motorola and Traveler. Claims construction is exactly the same as CBS. Haven't found reference to those. Anyone know anything about the provenance of that labeling?

I thought I read somewhere that the GTB versions of the CBS were really relabeled GE tubes. True?


----------



## JKDJedi (Aug 15, 2020)

highstream said:


> Came across a pair that are advertised as CBS 6SN7GT, two hole bad boy black plate D GETR testing as NOS 1955, but black bases say Motorola and Traveler. Haven't found reference to those. Anyone know anything about the provenance of that labeling?


Probably relabeled tubes.. I'm curious about the CBS-Hytron myself right now. There's some legit CBS-HYTRON tubes out there, when in doubt..just grab the real thing.
Now this tube has me wondering if it's a CBS-Hytron.. only for the lower D getter..


----------



## bcowen

JKDJedi said:


> Probably relabeled tubes.. I'm curious about the CBS-Hytron myself right now. There's some legit CBS-HYTRON tubes out there, when in doubt..just grab the real thing.
> Now this tube has me wondering if it's a CBS-Hytron.. only for the lower D getter..



I have a pair that are just Hytron labeled (no CBS). Have the bottom D-getter, but 3 hole plates:








Then another pair, same Hytron-only label, same bottom D-getter, but 2 hole plates. Interestingly, all 4 have the same date code of 51-39:





These are CBS labeled, but no Hytron. Short bottle, angled T-plates:





Then you turn it over, notice the etched dots, and spend the rest of the afternoon cleaning the hurl off the keyboard:





And then the Hytron *AND* CBS labeled 5692. Flat plates.  Can't see the getter shape at all as it's obscured by the flashing.  One of my favorite tubes in Cary preamps, but didn't light my fire in the Lyr 3 or the Vali 2. Haven't tried it in the Incubus:


----------



## Ranger Ron

JKDJedi said:


> Probably relabeled tubes.. I'm curious about the CBS-Hytron myself right now. There's some legit CBS-HYTRON tubes out there, when in doubt..just grab the real thing.
> Now this tube has me wondering if it's a CBS-Hytron.. only for the lower D getter..


Bottom mica looks like early sylvania


----------



## JKDJedi (Aug 15, 2020)

Ranger Ron said:


> Bottom mica looks like early sylvania





bcowen said:


> I have a pair that are just Hytron labeled (no CBS). Have the bottom D-getter, but 3 hole plates:
> 
> 
> 
> ...





Ranger Ron said:


> Bottom mica looks like early sylvania


I concur, just questioning the D getter . If Sylvania used D getters in 1945 then it's an early Sylvania in my book (the other detail I noticed is that a lot of the Sylvania photos out there show large lower getter flash material at the bottom, and a lot of photos of CBS-Hytron show hardly no getter flash material at the bottom.. )... And that 5692 sounds great on the Incubus.🙂


----------



## Ripper2860

bcowen said:


> I have a pair ... <insert make/mfg>...



Why am I not shocked.


----------



## highstream (Aug 15, 2020)

Given your curiosity in the Hytron's, I'll pass along my epxerience wtith eBay seller gizmo440, who has several posted. He doesn't test for noise or microphonics. I purchased a pair of 1953's from him last month for a Supratek preamp, and one was noisy right off. He sent a replacement right off, which worked great. But then after a few days I turn on my gear and then go fix lunch when I hear this loud machine like hum. Thought it was from the crew outside working on the condos across the way, but it was the other of the original pair apparently vibrating internally. Happened a few more times in the coming days after either turning on the preamp or just touching a balance knob by that tube. Tapping the tube stopped it, short of turning off the preamp, but this was more microphonics than normal. Otherwise, they sounded very good. However, this time gizmo440 claimed he didn't have any more Hytron's and so I returned the three and got a full refund. Looking today, he's got several for sale, including the ones he sold me.

I'd go with a 5692 pair, except they are going dear (Upscale Audio has them at $200 a pop).

I decided to go with a different pair just now, but the ones I was asking about are on eBay, titled " CBS 6SN7GT PERFECT MATCH PAIR 2 HOLE BAD BOY BLACK PLATE D GETR TEST NOS 1955," and look like... (there's a top view online)


----------



## JKDJedi

highstream said:


> Given your curiosity in the Hytron's, I'll pass along my epxerience wtith eBay seller gizmo440, who has several posted. He doesn't test for noise or microphonics. I purchased a pair of of 1953's from him last month for a Supratek preamp, and one was noisy right off. He sent a replacement right off, which worked great. But then after a few days I turn on my gear and then go fix lunch when I hear this loud machine like hum. Thought it was from the crew outside working on the condos across the way, but it was the other of the original pair apparently vibrating internally. Happened a few more times in the coming days after either turning on the preamp or just touching a balance knob by that tube. Tapping the tube stopped it, short of turning off the preamp, but this was more microphonics than normal. Otherwise, they sounded very good. However, this time gizmo440 claimed he didn't have any more Hytron's and so I returned the three and got a full refund. Looking today, he's got several for sale, including the ones he sold me.
> 
> I decided to go with a different pair just now, but the one's I was asking about areon eBay, titled " CBS 6SN7GT PERFECT MATCH PAIR 2 HOLE BAD BOY BLACK PLATE D GETR TEST NOS 1955" and look like... (there's a top view online)


Good to know...thanks... I'll stay away from that seller for sure. I had purchased a Black JAN NU couple weeks ago and the seller accidentally sent me a Raytheon 😂😂 he was apologetic about it of course. Sent it back to him yesterday.


----------



## JKDJedi (Aug 15, 2020)

Well you made me go look into the candy store and I couldn't resist grabbing one. ..😒 thanks . I think.


----------



## highstream (Aug 23, 2020)

JKDJedi said:


> Well you made me go look into the candy store and I couldn't resist grabbing one. ..😒 thanks . I think.



I received my pair today and got a surprise worth mentioning. They are CBS/Hytron 6SN7GTB Pair Side "D" Getter - Angled "T" Plates, CBS 1959 and Hytron 1960, measuring NOS like. Gizmo’s ones from the early ‘50’s that I returned had been modestly warm and inviting, similar to but an improvement on the Shuguang WE6SN7 I'd been using. These new ones, however, a dozen hours in are very different: clean, transparent, precise and tonally accurate, but just enough less warm to not feel drawn in, and a touch farther back and thinner with noticeably less body/resonance, and hence sense of presence. So much different that one's singer's voice was actually unrecognizable (her inflection disappeared). Of course, another 250-300 hours of burnin ahead, but nothing like expected so far. Maybe the CBS/Hytron went through a change in the late ‘50s?


----------



## highstream

Among the myriad of Sylvania 6SN7GT's available, I'm trying to identify these. Round mica with two posts, clear top, two-hole, but photos aren't great. Seller says date code is 126, but not sure if that means 1951 or could that be 1961. Any thoughts? Thanks,


----------



## Ranger Ron

highstream said:


> Among the myriad of Sylvania 6SN7GT's available, I'm trying to identify these. Round mica with two posts, clear top, two-hole, but photos aren't great. Seller says date code is 126, but not sure if that means 1951 or could that be 1961. Any thoughts? Thanks,


1951.


----------



## JKDJedi (Aug 24, 2020)

highstream said:


> Among the myriad of Sylvania 6SN7GT's available, I'm trying to identify these. Round mica with two posts, clear top, two-hole, but photos aren't great. Seller says date code is 126, but not sure if that means 1951 or could that be 1961. Any thoughts? Thanks,


Not sure on the dates but I do like how they sound. A touch livelier than the normal laid-back sound of the Sylvanias in that time frame (mentioned above) 🙂


----------



## sennfan83261

JKDJedi said:


> Not sure on the dates but I do like how they sound. 🙂


Not really a fan of the flat-plate Sylvania 6SN7GT's myself. The ones that came across my DV336 were a step below their t-plate brethren to my ears. It could be that the few that I took a flyer on may have been near the end of their lifespans.


----------



## Ranger Ron

I liked them at first, grew tired of them after a few days. Something about them fatigues me. Guy I bought them from said "one of the great hidden treasures of 6sn7" I dont think so.  Maybe I'll try them again someday when all else fails.


----------



## highstream

I'm trying to identify these tubes in the model range, not how they sound -- unless of course you listened to the exact same model.


----------



## Ranger Ron

highstream said:


> I'm trying to identify these tubes in the model range, not how they sound -- unless of course you listened to the exact same model.


Yes, the same model. 1951 flat plates, round micas.


----------



## highstream

Thanks for the info.


----------



## Ranger Ron

absolutely. They are impressive looking tubes I think.


----------



## highstream

Ranger Ron said:


> absolutely. They are impressive looking tubes I think.



You mean visually, not sonically, I take it.


----------



## JKDJedi

highstream said:


> Thanksgivin for the info.


Mine are rebranded Admiral and Motorola. One dated 1-26 the other 2-50.  When I want to change things up, these come out. Sound great with super warm 6080's


----------



## Ranger Ron

Yes. I agree with sennfann, a step below the t plate brethren


----------



## JKDJedi

Ranger Ron said:


> absolutely. They are impressive looking tubes I think.


Ask him about the rare brown based Sylvania he has, you still have it? @sennfan83261


----------



## sennfan83261 (Aug 24, 2020)

JKDJedi said:


> Ask him about the rare brown based Sylvania he has, you still have it? @sennfan83261


I never had one of the brown-base 6SN7WGT's or listened to one for that matter. I have a '49 black-base tan-lettering 6SN7GT (t-plates) that is really nice sounding. I don't know if the tan-lettering was applied on the base at the time of manufacture or later: https://www.head-fi.org/threads/the-6sn7-identification-guide.209782/post-15077189


----------



## JKDJedi

sennfan83261 said:


> I never had one of the brown-base 6SN7WGT's or listened to one for that matter. I have a '49 black-base tan-lettering 6SN7GT (t-plates) that is really nice sounding. I don't know if the tan-lettering was applied on the base at the time of manufacture or later: https://www.head-fi.org/threads/the-6sn7-identification-guide.209782/post-15077189


That's the one!! There was a brown in there somewhere.. 😁


----------



## bcowen

highstream said:


> Among the myriad of Sylvania 6SN7GT's available, I'm trying to identify these. Round mica with two posts, clear top, two-hole, but photos aren't great. Seller says date code is 126, but not sure if that means 1951 or could that be 1961. Any thoughts? Thanks,



Actually, the tube on the right looks like a 5-hole plate (on the left side).  Can't say I've ever seen one like that before...


----------



## Ripper2860

JKDJedi said:


> Ask him about the rare brown based Sylvania he has, you still have it? @sennfan83261




6SN7WGT/A are not too shabby.  I have a small stable of them and prefer it over the Hytron 5692 in Lyr 3.  Haven't tried it in Incubus yet.


----------



## tintinsnowydog

https://www.ebay.com.au/itm/3X-Earl...367115&hash=item56e1358879:g:8NYAAOSw6NdfMvYt

Are these rebranded bad boys, or a Canadian rebuild of them with Sylvania internals? Does anybody know how they sound compared to bad boys?


----------



## highstream

Slightly off topic, Anyone know if there some flat plate black glass Tung-Sol 6F8G’s that were rebranded as Sylvania?


----------



## Ranger Ron

highstream said:


> Slightly off topic, Anyone know if there some flat plate black glass Tung-Sol 6F8G’s that were rebranded as Sylvania?


I noticed those tubes as well. Rebranding was very very common. The internals are all that matter. As far as I know if the glass is black and not gray and the plates are flat my guess is that they must be TungSol. I have loads of 6f8g's and most of them are rebrands.


----------



## JKDJedi

tintinsnowydog said:


> https://www.ebay.com.au/itm/3X-Earl...367115&hash=item56e1358879:g:8NYAAOSw6NdfMvYt
> 
> Are these rebranded bad boys, or a Canadian rebuild of them with Sylvania internals? Does anybody know how they sound compared to bad boys?


Really hard to tell with no coding/date stamps on the tubes, or what I can tell on the photos. Bad Boys nickname was given to a certain time frame that falls outside of the 6SN7GTB line up, although the post could be misleading, or may not know exactly what these are (they could be 6SN7GT). My guess is they will have "The SOund".


----------



## JKDJedi

Ranger Ron said:


> I noticed those tubes as well. Rebranding was very very common. The internals are all that matter. As far as I know if the glass is black and not gray and the plates are flat my guess is that they must be TungSol. I have loads of 6f8g's and most of them are rebrands.


I found this listed write up on comparisons between a few 6F8G tubes, do you agree with most of it?

*Raytheon*: Very nice tube, I could live with it easily.
Open, extended, quick top end, full but pretty tight bass, lively/ percussive, forward soundstage, "loud," clear. Fun to listen to.

*Ken- Rad*: For some reason, this one took me for a trip. I really like this tube, but it seems to add more of it's own sound than any of the others, which could be a bad thing. It wouldn't be my pick overall, but very interesting to listen to.
Laid back, inviting, nice & fairly extended top end, warm "Mullardy" sound, low midrange emphasis, bass a bit slow, big forward soundstage, smooth, not very lively, easy going for extended listening.

*G.E*.: This one wouldn't be my choice at all, and I'd have to place it at the bottom of the heap. It wasn't _bad,_ but compared to the others, it just didn't do it for me.
"Solid" sounding, carved in stone, upper midrange emphasis, clear, at speaker soundstage, slightly tiring/ "in your face" comparatively, treble not as extended, slower bass.

*National Union RP*: My top choice for full time occupancy. It has the best balance of the traits I like.
Clear & clean, fast-er across the board, good balance, holographic & forward soundstage, musical, engaging, accurate (sounding,) warm, lively but easy for extended listening, all around hard to fault.

*RCA*: This one is nice, and I'd place it in at a close tie for 3rd/2nd. Can't go wrong with the RCA.
Warmest vocals, big & forward soundstage, not as extended on top comparatively but not bad, inviting, clean, slightly slower bass, extended & full bass, non fatiguing.

*Tung- Sol RP*: This is a favorite. Close 2nd/3rd for me.
Very extended on top end, very quick across the board, fun, holographic, forward soundstage, engaging, midrange not as full (dip,) tight extended bass, clear, exciting but good for extended listen.

*Sylvania:* Another great choice, can't go wrong. It could occupy the input position permanently w/o complaints.
Lively, nice treble although not as extended as some, a bit holographic & forward soundstage, images nicely, upper mid emphasis, bass extended but *slightly* slow, powerful, fun.

https://www.audioasylum.com/messages/tubes/221750/6f8g-vt99-observations


----------



## Ranger Ron

For the most part I agree with that write up. I'm not sure which Raytheon or Ken Rad is talked about there but the RCA NU and TSRPBBG seem spot on to me. All of the GE types I've seen have been rebrands so again hard to say what tube is being talked about.


----------



## Slade01

JKDJedi said:


> I found this listed write up on comparisons between a few 6F8G tubes, do you agree with most of it?
> 
> *Raytheon*: Very nice tube, I could live with it easily.
> Open, extended, quick top end, full but pretty tight bass, lively/ percussive, forward soundstage, "loud," clear. Fun to listen to.
> ...



I can't believe that 11 year old post is still one of the de-facto definitive guides to 6F8G comparisons.  But yeah they are still spot on.  It's funny, doesnt matter what variant/type of tube it is, Ken-Rads always seem to evoke a mixed reaction, and GEs (genuine GE made not rebranded) almost always suck the most.


----------



## sennfan83261

Slade01 said:


> I can't believe that 11 year old post is still one of the de-facto definitive guides to 6F8G comparisons.  But yeah they are still spot on.  It's funny, doesnt matter what variant/type of tube it is, Ken-Rads always seem to evoke a mixed reaction, and GEs (genuine GE made not rebranded) almost always suck the most.


Maybe time for a 6F8G/VT-99/6C8G/VT-163 lovers thread?


----------



## Ranger Ron

Slade01 said:


> I can't believe that 11 year old post is still one of the de-facto definitive guides to 6F8G comparisons.  But yeah they are still spot on.  It's funny, doesnt matter what variant/type of tube it is, Ken-Rads always seem to evoke a mixed reaction, and GEs (genuine GE made not rebranded) almost always suck the most.


Indeed. I have 6f8g labeled KenRads that have T plates, the staggered flat plate, and round plates.


----------



## sennfan83261 (Sep 4, 2020)

Ranger Ron said:


> Indeed. I have 6f8g labeled KenRads that have T plates, the staggered flat plate, and round plates.


Yeah, I've seen the same variation with my 6F8G Ken Rads, probably some of them rebrands. Kind of like the clear glass 6C8G Tung-Sol shown below. It looks exactly like my RCA two-mica meatball logo 6C8G expect that the round plates on the Tung-Sol feature wider separation than the round plates of the RCA. I have another clear glass 6C8G Tung-Sol with support rods between the two mica. I never seen a clear glass Tung-Sol for a 6C8G, as I thought all of the Tung-Sol 6F8G/6C8G's had black glass. I think that my Tung-Sols are rebrands, but from where? I took a flyer on them because they were cheap and I'm pleasantly surprised that I like them more than my Ken-Rads and National Unions 6C8G's [clearer sound, better technicalities (e.g. layering), widest soundstage, kind of more forward sounding than the others]. The Tung-Sols certainly sound way different to the  more closed-in, dry sounding RCA 6C8G's on my CTH. I have a black glass Tung-Sol 6C8G on the way and I hope it isn't microphonic. Damn, I thought I left tube-rolling behind when I ventured into the world of planars, but somehow it always draws me back, lol.


----------



## sennfan83261 (Sep 4, 2020)

Below is a visual aid to what I talked about earlier (6C8G's L to R: RCA, Tung-Sol, National Union). The other Tung-Sol 6C8G not pictured (because it is in my CTH while I'm listening to it right now  ) bears a closer resemblance to the pictured National Union 6C8G than the RCA and Tung-Sol below, but yet they sound dissimilar to each other. As far as I know, the Tung-Sol's could have been silk-screened on the base. The Tung-Sol not pictured has a date code that I don't jive with: 322613 (1961? Unlikely... 1946, 13th week?); the one picture is without a date code on the base. Whatever, they were cheap and they sound great!

Circling the wagons back to the 6SN7's, I remember buying a Jackson 6SN7GT with mouse-ears that looked like a clone of my Tung-Sol 6SN7GT mouse-ears. I thought it was a rebrand and it was a few bucks, so why not? The Jackson 6SN7GT was probably towards its end of its life because it sounded like ass compared to the branded Tung-Sol mouse-ears.


----------



## JKDJedi

sennfan83261 said:


> Below is a visual aid to what I talked about earlier (6C8G's L to R: RCA, Tung-Sol, National Union). The other Tung-Sol 6C8G not pictured (because it is in my CTH while I'm listening to it right now  ) bears a closer resemblance to the pictured National Union 6C8G than the RCA and Tung-Sol below, but yet they sound dissimilar to each other. As far as I know, the Tung-Sol's could have been silk-screened on the base. The Tung-Sol not pictured has a date code that I don't jive with: 322613 (1961? 1946, 13th week?); the one picture is without a date code on the base. Whatever, they were cheap and they sound great!
> 
> Circling the wagons back to the 6SN7's, I remember buying a Jackson 6SN7GT with mouse-ears that looked like a clone of my Tung-Sol 6SN7GT mouse-ears. I thought it was a rebrand and it was a few bucks, so why not? The Jackson 6SN7GT was probably towards its end of its life because it sounded like ass compared to the branded Tung-Sol mouse-ears.


46 more like it... heck maybe even 36! For sure not a 61, Have an RCA 6F8G (flat plates) I haven't rolled yet, maybe this weekend.


----------



## attmci

sennfan83261 said:


> Below is a visual aid to what I talked about earlier (6C8G's L to R: RCA, Tung-Sol, National Union). The other Tung-Sol 6C8G not pictured (because it is in my CTH while I'm listening to it right now  ) bears a closer resemblance to the pictured National Union 6C8G than the RCA and Tung-Sol below, but yet they sound dissimilar to each other. As far as I know, the Tung-Sol's could have been silk-screened on the base. The Tung-Sol not pictured has a date code that I don't jive with: 322613 (1961? Unlikely... 1946, 13th week?); the one picture is without a date code on the base. Whatever, they were cheap and they sound great!
> 
> Circling the wagons back to the 6SN7's, I remember buying a Jackson 6SN7GT with mouse-ears that looked like a clone of my Tung-Sol 6SN7GT mouse-ears. I thought it was a rebrand and it was a few bucks, so why not? The Jackson 6SN7GT was probably towards its end of its life because it sounded like ass compared to the branded Tung-Sol mouse-ears.


All my TS 6C8G has black glass.


----------



## sennfan83261 (Sep 4, 2020)

attmci said:


> All my TS 6C8G has black glass.


Which is why I said that it may be a rebrand in my earlier post, as I'm accustomed to seeing TS 6C8G RP's with black glass. So, I was and still remain a bit skeptical. IIRC, Tung-Sol and RCA made tubes for each other in the 1930's and/or 1940's. However, there are marked differences between clear glass "TS" shown in my post and the RCA 6C8G (meatball logo, two circular micas) pictured alongside it: larger gap between the RP's and different sized rivet holes. More important than the eye test, they pass the ear test, as the TS clear-glass sounds completely different to the RCA and better (to me) than my Ken-Rads, National Unions, and RCA's. My other clear glass Tung-Sol has 322613 stamped in its base, 322 indicating that Tung-Sol manufactured it. Still, who knows if the EIA code goes back to the late '30s or '40s? Or if the code was fraudulently silk-screened on the base? If someone tried to pull one over me for $15-20, they should have picked a crappier sounding tube. I guess what remains is the comparing the clear glass TS to the black glass TS 6C8G that's on my way.


----------



## bcowen

sennfan83261 said:


> Damn, I thought I left tube-rolling behind....



There is no cure.  Trust me -- I've read the internet from start to finish looking for one.


----------



## JKDJedi

sennfan83261 said:


> Which is why I said that it may be a rebrand in my earlier post, as I'm accustomed to seeing TS 6C8G RP's with black glass. So, I was and still remain a bit skeptical. IIRC, Tung-Sol and RCA made tubes for each other in the 1930's and/or 1940's. However, there are marked differences between clear glass "TS" shown in my post and the RCA 6C8G (meatball logo, two circular micas) pictured alongside it: larger gap between the RP's and different sized rivet holes. More important than the eye test, they pass the ear test, as the TS clear-glass sounds completely different to the RCA and better (to me) than my Ken-Rads, National Unions, and RCA's. My other clear glass Tung-Sol has 322613 stamped in its base, 322 indicating that Tung-Sol manufactured it. Still, who knows if the EIA code goes back to the late '30s or '40s? Or if the code was fraudulently silk-screened on the base? If someone tried to pull one over me for $15-20, they should have picked a crappier sounding tube. I guess what remains is the comparing the clear glass TS to the black glass TS 6C8G that's on my way.


Please. Chime in with that comparison.


----------



## sennfan83261 (Sep 5, 2020)

JKDJedi said:


> Please. Chime in with that comparison.


Sure thing! So I received my TS black-glass round-plate (BGRP) 6C8G the other day, and what was immediately apparent was the large soundstage and clarity provided by it to the CTH (most preamp TS tubes that I've tried seemed to be more on the clearer side of things rather than reverby). Other TS pre-amp tubes that I've tried include the 6SN7GT mouse-ears (black plates and gray plates) and the 6SN7GTB in my Darkvoice. With the clear-glass (CG) branded TS 6C8G's, the clarity was there, but a touch less than the TS BGRP, and the soundstage was just as large. The TS CGRP's were also slightly less forward than the TS BGRP and maybe a touch warmer (really too close to tell since I only have one CTH and can't immediately switch back and forth to compare). Both the TS BGRP and the TS CGRP 6C8G's exhibit nice layering capabilities due to their large soundstage and clarity and are both head and shoulders over the RCA meatball logo, round-micas 6C8G pictured below, the latter of which is rather dry sounding and lacking technicalities. Since my three TS 6C8G's cost between $14-25 a piece, I'm not going to be too chuffed if the TS CGRP's are a rebrand since they seem to be produced more towards to Tung-Sol's specifications, at least to my ears.

BTW, how is the RCA gray glass flat-plate 6F8G? Did you roll them into your DV336? My DV336 that I left behind in my city apartment is driven by an RCA gray glass (RP or FP? I forgot) 6F8G too.

6C8G's pictured below (L to R): RCA (S4E), TS CGRP, TS BGRP, TS CGRP (322613), National Union


----------



## JKDJedi (Sep 5, 2020)

sennfan83261 said:


> Sure thing! So I received my TS black-glass round-plate (BGRP) 6C8G the other day, and what was immediately apparent was the the large soundstage and the clarity provided by it to the CTH (most preamp TS tubes that I've tried seemed to be more on the clearer side of things rather than reverby). Other TS pre-amp tubes that I've tried include the 6SN7GT mouse-ears (black plates and gray plates) and the 6SN7GTB in my Darkvoice. With the clear-glass (CG) branded TS 6C8G's, the clarity was there, but a touch less than the TS BGRP, and the soundstage was just as large. The TS CGRP's were also slightly less forward than the TS BGRP and maybe a touch warmer (really too close to tell since I only have one CTH and can't immediately switch back and forth to compare). Both the TS BGRP and the TS CGRP 6C8G's exhibit nice layering capabilities due to their large soundstage and clarity and are both head and shoulders over the RCA meatball logo, round-micas 6C8G pictured below, the latter of which is rather dry sounding and lacking technicalities. Since my three TS 6C8G's cost between $14-25 a piece, I'm not going to be too chuffed if the TS CGRP's are a rebrand since they seem to be produced more towards to Tung-Sol's specifications, at least to my ears.
> 
> BTW, how is the RCA gray glass flat-plate 6F8G? Did you roll them into your DV336? My DV336 that I left behind in my city apartment is driven by an RCA gray glass (RP or FP? I forgot) 6F8G too.
> 
> 6C8G's pictured below (L to R): RCA (S4E), TS CGRP, TS BGRP, TS CGRP (322613), National Union


Loving it! An all day tube. Rolls well with the 7236. Nice width. Would love to have one of them Tung Sol. Nice collection there.


----------



## highstream (Sep 10, 2020)

Anyone seen this Psvane tube version before? Recognize what the name on top is?


----------



## Slade01

highstream said:


> Anyone seen this Psvane tube version before? Recognize what the name on top is?



I believe this may have been stock tubes for the OldChen tube amps.  example:  (https://www.hifi-amplifiers.com/en/...eamplifier-bass-adjustment-preamp-p-5541.html)


----------



## sennfan83261

Slade01 said:


> I believe this may have been stock tubes for the OldChen tube amps.  example:  (https://www.hifi-amplifiers.com/en/...eamplifier-bass-adjustment-preamp-p-5541.html)



From the description of the amp: "1. With the direct amplification function of ordinary bile preamp, and adding a moderate high and low tone adjustment..."

Oh, Chingrish...

Anyways, those tubes look like tubes even a grandma would love, who could probably ID 6SN7's better than we can, lol.


----------



## highstream

Thanks. I saw them on eBay, but the gd-parts site link for the tube goes to AliExpress, where it says they have a 1000 pairs.


----------



## tintinsnowydog

Just received 4 of these General Electric Canada 6SN7GT, any insight onto their history, what the gray collar may be for and date? Has date code H3 as far as I can see.


----------



## JKDJedi

tintinsnowydog said:


> Just received 4 of these General Electric Canada 6SN7GT, any insight onto their history, what the gray collar may be for and date? Has date code H3 as far as I can see.


Those might be Sylvania, and the collar could be a remedy for a loose base.


----------



## tintinsnowydog

JKDJedi said:


> Those might be Sylvania, and the collar could be a remedy for a loose base.


Construction does look almost identical to a couple Sylvania VT231 I can see, just the bottom getter is different (rectangular open getter). Did Sylvania operate factories in Canada?  Wonder if anything else would narrow down the date ranges.


----------



## JKDJedi

tintinsnowydog said:


> Construction does look almost identical to a couple Sylvania VT231 I can see, just the bottom getter is different (rectangular open getter). Did Sylvania operate factories in Canada?  Wonder if anything else would narrow down the date ranges.


Then probably CBS-Hytron . Not sure if Sylvania ever did have factory in Canada, but a lot of tubes did get outsourced to Canada. Marconi is one company that comes to mind that had almost all their tubes outsourced.


----------



## lupoal (Sep 22, 2020)

Hi,
I have here two tubes that looks like Sylvania but, unfortunately, do not have any name anywhere... here are some pictures, is there anybody that could help me in recognize them?  Do thanks in advance


----------



## Ranger Ron

JKDJedi said:


> Then probably CBS-Hytron . Not sure if Sylvania ever did have factory in Canada, but a lot of tubes did get outsourced to Canada. Marconi is one company that comes to mind that had almost all their tubes outsourced.


Rogers branded tubes out of Canada all look very similar to sylvania.


----------



## Tom-s

Here's a riddle for everyone! 
Haven't found a picture online of a second specimen, that's why it's here for you!

I'm a warm sounding European SN7 and I lack controlled heater warm-up.
What am I?


----------



## bcowen

Tom-s said:


> Here's a riddle for everyone!
> Haven't found a picture online of a second specimen, that's why it's here for you!
> 
> I'm a warm sounding European SN7 and I lack controlled heater warm-up.
> What am I?



Hmmm...perhaps a Brimar 6SN7GTY?


----------



## Ranger Ron

bcowen said:


> Hmmm...perhaps a Brimar 6SN7GTY?


Fivre?


----------



## JKDJedi

Tom-s said:


> Here's a riddle for everyone!
> Haven't found a picture online of a second specimen, that's why it's here for you!
> 
> I'm a warm sounding European SN7 and I lack controlled heater warm-up.
> What am I?


You'll have to send that to me for further evaluation, Brimar?


----------



## Tom-s

Thanks for playing along guys, much appreciated! No one's close.

Another set of hints. This is the current setup (don't do OPT rolling, hugely impractical as can be seen).
The output tubes will teach you the heater voltage. The code seen, the Island of origin. The before told hints the actual brand. 
The actual factory was owned by different "companies" over the years. In the early '50s this company (and it's parent company) took over and produced this tube (apparently).


----------



## JKDJedi

Tom-s said:


> Thanks for playing along guys, much appreciated! No one's close.
> 
> Another set of hints. This is the current setup (don't do OPT rolling, hugely impractical as can be seen).
> The output tubes will teach you the heater voltage. The code seen, the Island of origin. The before told hints the actual brand.
> The actual factory was owned by different "companies" over the years. In the early '50s this company (and it's parent company) took over and produced this tube (apparently).


And this is a 6sn7 tube correct? Nice amp, custom?


----------



## attmci

Tom-s said:


> Here's a riddle for everyone!
> Haven't found a picture online of a second specimen, that's why it's here for you!
> 
> I'm a warm sounding European SN7 and I lack controlled heater warm-up.
> What am I?


We had discussed b4. There is no Mullard 6SN7GT. https://www.whatsbestforum.com/threads/mullard-6sn7gt-help-please-info-needed.15277/

They are all made by _______ . hahaha.


----------



## JKDJedi

attmci said:


> We had discussed b4. There is no Mullard 6SN7GT. https://www.whatsbestforum.com/threads/mullard-6sn7gt-help-please-info-needed.15277/
> 
> They are all made by _______ . hahaha.


Most likely Brimar.


----------



## Ripper2860 (Sep 27, 2020)

Not sure what the mystery tube is, but while it does look similar to a Brimar, I'm going to go with it not being Brimar.  Top mica is just not what I'm used to seeing on a Brimar 6SN7GT/Y or CV1988.


----------



## sennfan83261

Tom-s said:


> Thanks for playing along guys, much appreciated! No one's close.


If someone gets it right, does that person get the tube amp that's pictured in your post?


----------



## cddc

Tom-s said:


> Here's a riddle for everyone!
> Haven't found a picture online of a second specimen, that's why it's here for you!
> 
> I'm a warm sounding European SN7 and I lack controlled heater warm-up.
> What am I?






This is definitely a weirdo 6SN7. 

It is definitely not a Brimar, as Brimar comes with round plates but this one has flat plates.

Fivre does come with staggered plates, but it normally comes with clear glass, and its top mica is much narrower, so not likely a Fivre as well.

I was initially going to guess it’s a Philips/Pope tube out of Holland, given Tom’s European background (very likely from Holland as well, right?). I have seen some RCA grey glass like tubes that are actually Holland-made Philips, but these Philips tubes come with parallel flat plates instead of staggered plates as shown.

Now, from the tube-on-amp pic I’ve known it’s a British tube, as the pic shows the CV logo for British military. And the brown base looks like some BVA tubes. So is it a Mullard or GEC tube? But I’ve seen GEC/Marconi/Osgram 6SN7’s (aka B65’s), and these do not have staggered plates. Also, Mullard never made any 6SN7 tubes as far as I know. So is it an engineering sample from the BVA group?


----------



## Tom-s (Sep 28, 2020)

Last weekend I rebuild the previously pictured self build 1626 Darling amplifier (also found on this forum, sold as Amps and Sound Kenzie) that's doing speaker duty in my study.
I rewired the driver section from 12SL7 to 12SN7 (Led bias, CCS@4ma) and started looking around my collection for 12SN7's when this tube was found in one of the boxes.
Yesterday (see pictures) the Darling amp had it's small blue Edcor on there, starting today it's singing with massive AE transformers (build for 300b kind of power).



I scratched my head a little as I had never seen a tube like this.
CV925 made in Tottenham UK, with broad arrow and a Tottenham top mica plate.

Here's a CV1932 Mullard made in Tottenham (6J5 for US) mica for comparison, notice the similarities?
So that's half a SN7, and we agree you can buy actual 6J5's made by Mullard.



It also wears the Philips tube code 0K1 (12SN7) J5F (Tottenham June 1955?).

So is it SN7? An unexpected coincidence or confirmation of this came at it's bottom (as with other Philips / Mullard tubes).

The writing here says 2SN or 28N, but i like to read 2SN as a way of telling a 12SN7.




So, is it a true SN7 and not a 33 or 32 equivalent like Mullard is known for?
Here's the test results and traced curvers of the actual tube -> It's a true 12SN7!



@cddc You were really close! Good thinking!
As far as i know Philips Heerlen/Eindhoven factories never did a 6SN7. I have a bunch wearing all sorts of Philips type labels, with RCA type build.
And the type B65 in my collection is staggered plates (can't get it in a picture because of the black coating).


----------



## bcowen (Sep 28, 2020)

cddc said:


> This is definitely a weirdo 6SN7.
> 
> It is definitely not a Brimar, as Brimar comes with round plates but this one has flat plates.
> 
> ...



@Tom-s didn't say it was a 6SN7.  His first post was that it was an "SN7".  So either he typo'd or that was intentional, alluding to the possibility it could be a 12SN7.  I still don't have a clue what it is, other than possibly an MO-Valve (Marconi/Osram vintage) as GEC acquired MO Valve satisfying at least that part of the mystery.   

Edit:  Nevermind.  I was minute too late posting.  LOL!


----------



## cddc

I know   as soon as someone (intentionally/unintentionally) drops the number before SN7, it’s very likely a 12SN7 / 25SN7 tube.

They are essentially the same tube with just different heater voltages.


----------



## cddc

Tom-s said:


> Last weekend I rebuild the previously pictured self build 1626 Darling amplifier (also found on this forum, sold as Amps and Sound Kenzie) that's doing speaker duty in my study.
> I rewired the driver section from 12SL7 to 12SN7 (Led bias, CCS@4ma) and started looking around my collection for 12SN7's when this tube was found in one of the boxes.
> Yesterday (see pictures) the Darling amp had it's small blue Edcor on there, starting today it's singing with massive AE transformers (build for 300b kind of power).
> 
> ...




Tom, thanks a lot for those eye candies and tube info, really enjoyed reading them 

You really have lots of cool tubes and tube-related stuff  😍… I wish I could live in Europe to have access to these delicious exotic European NOS tubes.

Are you going to turn the amp into a 300B amp, since it's now equipped with transformers capable of driving 300B tubes (thou 300B could be a big pit for anyone's $$$  😜)?


----------



## bcowen

attmci said:


> We had discussed b4. There is no Mullard 6SN7GT. https://www.whatsbestforum.com/threads/mullard-6sn7gt-help-please-info-needed.15277/
> 
> They are all made by _______ . hahaha.



I see what you did there. Even confused me for a minute (which is admittedly not terribly difficult).


----------



## attmci

bcowen said:


> I see what you did there. Even confused me for a minute (which is admittedly not terribly difficult).


It's kind of insane to just show a picture of part of the tube and let others to guess what kind of tube it is. Lesson learned.


----------



## Ripper2860

Cruel and unusual punishment, if you ask me.  (And you didn't)


----------



## bcowen

attmci said:


> It's kind of insane to just show a picture of part of the tube and let others to guess what kind of tube it is. Lesson learned.



OK, give me my avatar back...you're still confusing me.


----------



## attmci (Sep 29, 2020)

bcowen said:


> OK, give me my avatar back...you're still confusing me.


Now, do you want to trade avatar?


----------



## JTbbb

Hello there, I’m fairly new to tube amps and tube rolling and am thoroughly enjoying this aspect of the hobby. However, I have recently bought a couple of tubes and am having trouble working out the date of manufacture. Any ideas? If needed I could do some better photos tomorrow. Thanks in advance.


----------



## JKDJedi

JTbbb said:


> Hello there, I’m fairly new to tube amps and tube rolling and am thoroughly enjoying this aspect of the hobby. However, I have recently bought a couple of tubes and am having trouble working out the date of manufacture. Any ideas? If needed I could do some better photos tomorrow. Thanks in advance.


Those are early to.mid 40's tubes


----------



## highstream

Depending on the application and condition of the tubes, those should sound very nice.


----------



## JTbbb

Thank you for your help JKDjedi, and yes indeed they sound very nice.

JKDjedi, how do you know the approximate date? Is it from the construction or the code? Just curious.


----------



## JKDJedi (Oct 23, 2020)

JTbbb said:


> Thank you for your help JKDjedi, and yes indeed they sound very nice.
> 
> JKDjedi, how do you know the approximate date? Is it from the construction or the code? Just curious.


VT231 tubes are wartime tubes. The war ended in 1945. we would need a seasoned member here to decipher the code stamped on that tube.  Did a quick search for ya.. most likely 1944 from the codes


----------



## highstream (Oct 24, 2020)

JKD is correct. While I'm not an expert, but the VT-xx numbers, which I read are stock numbers, typically indicate WWII vintage. JAN is military - "joint army/navy" I think, but not necessarily WWII. But the military requirements generally called for more durable builds, less prone to vibration (think fighter planes). Also go back and read the beginning posts of this forum or https://www.head-fi.org/threads/the-reference-6sn7-thread.117677/.

Also may be of help...
http://www.dehavillandhifi.com/6sn7_vt.htm
https://www.head-fi.org/threads/shootout-of-nos-6sn7-tubes.932083/
http://www.audiotubes.com/6sn7.htm
and...



In addition, the 6F8G is an excellent and often less costly equivalent, actually the 6SN7's predecessor, but they do require an adapter to plug into a 6SN7 socket (eBay from China or Woo Audio).


----------



## JTbbb

Daft question I think....but there is no such tube marked up Tung Sol 6SN7 VT231? Or with any other manufacturers name.


----------



## JKDJedi

JTbbb said:


> Daft question I think....but there is no such tube marked up Tung Sol 6SN7 VT231? Or with any other manufacturers name.


Not sure what the question is. 🤔😐


----------



## JTbbb

JKDJedi said:


> Not sure what the question is. 🤔😐



Ok, I’ll try again . I know there will be a Tung Sol 6SN7GT VT-231, but is there a Tung Sol 6SN7 VT-231?


----------



## highstream

From Wikipedia:
American military designator for the 6SN7GA is *VT-231*, and the British called it *CV1988*. European designations include the 1942 *ECC32* (not an exact equivalent), *13D2* and *B65*.

Tung-Sol had a version in the 1940s: http://www.vacuumtubes.com/6sn7.html

Btw, these are the kinds of questions that I learned a lot about from scratch doing searches and poking around online.


----------



## JKDJedi

JTbbb said:


> Ok, I’ll try again . I know there will be a Tung Sol 6SN7GT VT-231, but is there a Tung Sol 6SN7 VT-231?


copy, from a quick looks, I don't think there ever was a Tung Sol *6SN7* (VT231).. just the *6SN7GT* (VT231) Since these were all built in the 40's, I can not find any *6SN7* Tung Sol anywhere of any reference on the internet, interesting. Anybody?


----------



## JTbbb

highstream said:


> From Wikipedia:
> American military designator for the 6SN7GA is *VT-231*, and the British called it *CV1988*. European designations include the 1942 *ECC32* (not an exact equivalent), *13D2* and *B65*.
> 
> Tung-Sol had a version in the 1940s: http://www.vacuumtubes.com/6sn7.html
> ...



Thank you. I am learning a lot, it’s fascinating. Just the occasional dumb question!


----------



## JKDJedi

JTbbb said:


> Thank you. I am learning a lot, it’s fascinating. Just the occasional dumb question!


Hey, all good in the neighbor hood, good question really.


----------



## JTbbb

Just looking at a pair of Raytheon JAN-CRP 6SN7GT VT-231 NIB £105. Seems fair price.


----------



## highstream (Oct 25, 2020)

Another good site to mention is tubemaze.info, e.g., https://tubemaze.info/raytheon-crp-6sn7gt-d-getter-black-plates/. His eBay store has a 1950 version.


----------



## attmci

highstream said:


> From Wikipedia:
> American military designator for the 6SN7GA is *VT-231*, and the British called it *CV1988*. European designations include the 1942 *ECC32* (not an exact equivalent), *13D2* and *B65*.
> 
> Tung-Sol had a version in the 1940s: http://www.vacuumtubes.com/6sn7.html
> ...


Ecc33


----------



## highstream

Seem to be same family:
http://www.nosvacuumtubes.net/product/mullard-philips-ecc33/
https://www.radiomuseum.org/tubes/tube_ecc32.html
good info and links: https://www.head-fi.org/threads/ecc31-ecc32-ecc33-ecc34-ecc35-tube-addicts.808322/ (note leftside's post 12)


----------



## GreenNeedle

Does anyone know who made tubes for RTRA?

https://www.ebay.co.uk/itm/RTRA-6SN...700047?hash=item340924b54f:g:SekAAOSwMYRaftSa


----------



## JTbbb

Hello there, my most recent purchase is a pair of these. I guess they are what might be called type 1’s as there are just 2 support rods? Do the numbers give the date of manufacture? Or can it only be tied down to 40’s? Or 50’s


----------



## tintinsnowydog (Oct 31, 2020)

GreenNeedle said:


> Does anyone know who made tubes for RTRA?
> 
> https://www.ebay.co.uk/itm/RTRA-6SN...700047?hash=item340924b54f:g:SekAAOSwMYRaftSa


I took a guess on another thread that these have similar plate and top mica supports as 6N8S, but am not sure.



JTbbb said:


> Hello there, my most recent purchase is a pair of these. I guess they are what might be called type 1’s as there are just 2 support rods? Do the numbers give the date of manufacture? Or can it only be tied down to 40’s? Or 50’s


VT-231 suggests pre-1950. FE5 suggests 1945, but not too sure on the FE. A quick google found this ebay post
https://www.ebay.com.au/itm/RAYTHEON-VT-231-6SN7GT1945-JAN-CRP-ONE-TUBE-NOS-/264272379103
Original box agrees that LE 5 and FE 5 are 1945. F= June L= November/December potentially?

Edit: box stamped April 1945.


----------



## GreenNeedle

One more (I'm in an ebay mood today.)

From what I read Zalytron rebranded rather than manufactured tubes.  This one clearly states on the base 1959 but it look similar to a Bad Boy to me.  Did someone else manufacture a tube similar after Sylvania?  Did Zalytron rebrand some much older tubes in 1959?  Any details would be cool.

https://www.ebay.co.uk/itm/6SN7GT-Z...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


----------



## attmci

highstream said:


> Seem to be same family:
> http://www.nosvacuumtubes.net/product/mullard-philips-ecc33/
> https://www.radiomuseum.org/tubes/tube_ecc32.html
> good info and links: https://www.head-fi.org/threads/ecc31-ecc32-ecc33-ecc34-ecc35-tube-addicts.808322/ (note leftside's post 12)


But different tubes.


----------



## Ranger Ron

GreenNeedle said:


> One more (I'm in an ebay mood today.)
> 
> From what I read Zalytron rebranded rather than manufactured tubes.  This one clearly states on the base 1959 but it look similar to a Bad Boy to me.  Did someone else manufacture a tube similar after Sylvania?  Did Zalytron rebrand some much older tubes in 1959?  Any details would be cool.
> 
> https://www.ebay.co.uk/itm/6SN7GT-Zalytron-Foil-Getter-at-Base-A-Used-Old-Stock-Valve-Tube-1pc-DEC19/193241313051?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649


Zalytron absolutely sounds like a rebrand.


----------



## attmci

Ranger Ron said:


> Zalytron absolutely sounds like a rebrand.


It's a Syl. But cannot confirm it's a bad boy.


----------



## Ripper2860

Technically not a bad boy if the 1959 year stamp is accurate.  Legit Bad Boys were late '51 to early '53.


----------



## tintinsnowydog

The internals certainly match up the criteria (3 hole, top mica spiked and pointing down, foil getter). Technically not a bad boy because it isn’t branded Sylvania and printed 1951/2/3, but it potentially sounds the same. Theres the same case of Canadian Marconi GTB with same internals, but different branding. Bases can be put on or printed any time, but the internals are most likely from the same run.


----------



## cddc

LOL, you guys are nit-picky on the year 1959.

Zalytron is a UK rebrander, it might order the batch of tubes from Sylvania in 1953, it took a year or 2 for the tubes to reach the UK, then sitting in their warehouse for another couple of years until Zalytron finally silk printed its logo and year 1959 on the base, and shipped them out.

That tube is a real bad boy.


----------



## Ripper2860 (Oct 31, 2020)

@cddc got in just before I hit submit.  😄

All the characteristics of a Bad boy.  IMHO - never fully trust any dates stamped on the base. Many times tubes are made well in advance of being mounted to a base.  Rely on internal structure and on any codes etched onto on the glass envelope itself.


----------



## attmci (Oct 31, 2020)

attmci said:


> It's a Syl. But cannot confirm it's a bad boy.


Because I cannot see the internal structures. The seller intentionally hide the details.

You guys can see through?


----------



## Ripper2860 (Nov 1, 2020)

Enough of the internal structure is visible on the Zalytron to allow a relatively accurate assessment, IMHO.  While we cannot see if there's a rectangular foil getter holder, the pics show:  Copper posts. Bottom flashing extending up approx. 1/3 of tube. Top rectangular mica with 3- slightly downward pointing points on each of the short sides.  Bottom rectangular mica.  Ribbed t-plates with 3 rivet holes each.  Those are all characteristics of the Sylvania-made 6SN7GT dubbed 'Bad Boy' by some folks.  If the 1959 year on the base actually reflects the tube MFG date, then it most certainly falls well outside the range specified for a true 'Bad Boy', but as I stated previously -- the base is not the best indicator.  Example:  I have a 1945 Sylvania tall bottle / black base 6SN7W tube mounted in a 6SN7GT base.  The tube is etched 6SN7W on the top of the envelope.  All others I own and I've seen are in a base marked JAN CHS 6SN7W.


----------



## attmci (Nov 1, 2020)

attmci said:


> Because I cannot see the internal structures. The seller intentionally hide the details.
> 
> You guys can see through?


I saw three holes on one side only. Just different angles. I could be wrong. Don't care about the date at all.

BTW, the bad boy is not as good as a 6sn7w. Not worth the 40 plus pounds plus shipping price tag. 

Your guy's
 best friend has one bad boy on sale now (30% off):

https://www.ebay.com/itm/6SN7GT-BAD...612759?hash=item2af5de4bd7:g:60QAAOSwnF1fnKTg


----------



## Ripper2860 (Nov 1, 2020)

No thanks. I have several and never paid over $55 on average.  And I agree, the W is a better sounding tube in my opinion.


----------



## cddc (Feb 27, 2021)

attmci said:


> I saw three holes on one side only. Just different angles. I could be wrong. Don't care about the date at all.
> 
> BTW, the bad boy is not as good as a 6sn7w. Not worth the 40 plus pounds plus shipping price tag.
> 
> ...




LOL....*Menifee_Audio*  (aka BangyBang) is a notorious scammer. Not only he asks for 4x - 10x ongoing market prices, but also he is very sneaky on his tube measurements. He never tells you what tester he uses and when his tester was last calibrated, so it's basically the same thing as having no tester. And he is demanding extremely high prices...what a joke!

*greengirl613* is slightly better than Menifee, though GreenGirl613 is also asking ridiculous prices and being dishonest (he uses lots of accounts to fool buyers, *greengirl613*, *thegeminigirl*, *fng2u, oceanview_hi, ....,* just name a few), his tube testing values at least seem normal.

Other suspicious sellers you guys should pay attention to are * igolioto and brhines2012* . They use some crappy out-of-tune TV-3 and Mercury testers that often give 3500-3600 Micromhos to 6SN7 tubes. It is impossible for a 6SN7 (100% NOS = 2600 Micromhos) to reach such a high measurement, if you often check tube measurements on higher grade testers like TV-7 on fleabay, you'll know their numbers are just jokes. If you buy 6SN7's from them, make sure they test at least 3500 Micromhos on their testers, a 3100-3200 Micromhos tube from their testers could possibly measure only 80% on a truly calibrated tester.

Will let you guys know other suspicious sellers if I notice them.


----------



## bcowen

cddc said:


> LOL....*Menifee_Audio* (aka BangyBang) is a notorious scammer. Not only he asks for 4x - 10x ongoing market prices, but also he is very sneaky on his tube measurements. He never tells you what tester he uses and when his tester was last calibrated, so it's basically the same thing as having no tester. And he is demanding extremely high prices...what a joke!
> 
> *greengirl613* is slightly better than Menifee, though GreenGirl613 is also asking ridiculous prices and being dishonest (he uses lots of accounts to fool buyers, *greengirl613*, *thegeminigirl*, *fng2u, oceanview_hi, ....,* just name a few), his tube testing values at least seem normal.
> 
> ...



I've seen a number of *igolioto*'s listings and never paid any attention to them because the prices were always ludicrous.  But after looking at the stupidly priced one below, you're absolutely right on his test readings.  3125/3125?  Yeah.  Sure.

I have a TV-3 sitting in the closet. Despite my best efforts (and a *lot* of time spent on it) I cannot get it to calibrate. All of the Hickok military testers have a lengthy and arduous calibration procedure that requires some good test equipment, and there are very few people that can calibrate one correctly even if they have the equipment (Dan Nelson is one, but one of very few).  Igolioto's TV-3 is nowhere near correct calibration (regardless of his claim) if he's getting test readings like that.

https://www.ebay.com/itm/2-NEW-Tung...614618?hash=item3433475e5a:g:rsUAAOSwSPFfi4DA


----------



## ScubaMan2017

cddc said:


> LOL....*Menifee_Audio* (aka BangyBang) is a notorious scammer. Not only he asks for 4x - 10x ongoing market prices, but also he is very sneaky on his tube measurements. He never tells you what tester he uses and when his tester was last calibrated, so it's basically the same thing as having no tester. And he is demanding extremely high prices...what a joke!
> 
> *greengirl613* is slightly better than Menifee, though GreenGirl613 is also asking ridiculous prices and being dishonest (he uses lots of accounts to fool buyers, *greengirl613*, *thegeminigirl*, *fng2u, oceanview_hi, ....,* just name a few), his tube testing values at least seem normal.
> 
> ...


Crimme. Buyer beware eh...


----------



## ScubaMan2017

bcowen said:


> I've seen a number of *igolioto*'s listings and never paid any attention to them because the prices were always ludicrous.  But after looking at the stupidly priced one below, you're absolutely right on his test readings.  3125/3125?  Yeah.  Sure.
> 
> I have a TV-3 sitting in the closet. Despite my best efforts (and a *lot* of time spent on it) I cannot get it to calibrate. All of the Hickok military testers have a lengthy and arduous calibration procedure that requires some good test equipment, and there are very few people that can calibrate one correctly even if they have the equipment (Dan Nelson is one, but one of very few).  Igolioto's TV-3 is nowhere near correct calibration (regardless of his claim) if he's getting test readings like that.
> 
> https://www.ebay.com/itm/2-NEW-Tung...614618?hash=item3433475e5a:g:rsUAAOSwSPFfi4DA


...seven hundred fifty dollars. US funds. Whatever the market will bear, I guess. Nope. Not for me.


----------



## highstream

Gizmo440 doesn't test for noise. If I recall correctly, three out of four early 1950s CBS Hytrons from him were noisy (would start humming on their own or upon my merely touching the preamp). Then he "didn't have anymore" to send. Which of course wasn't true: he soon put a lot more up on eBay, including the ones I had sent back (think they are still there). I will say that when they worked, they sounded awfully good.


----------



## bcowen

Just ran across this. I've never bought from this seller, but a very good price on ribbed plate 50's Fotons which are becoming harder and harder to find.

You'd think though that a Russian seller would know the ribbed plates went from 1951 to 1956, not 1952.   

https://www.ebay.com/itm/Lot-of-1-pc-6N8S-6SN7GT-Foton-1950s-Ribber-Anode-Audiophile-Triode-Tube-NOS/333741784939?_trkparms=aid=1110010&algo=HOMESPLICE.DISCCARDS&ao=1&asc=225073&meid=92a6cb73db98421fa5c386d34f542a39&pid=100009&rk=1&rkt=2&sd=114495700815&itm=333741784939&pmt=1&noa=0&pg=2047675&algv=default&brand=Foton&_trksid=p2047675.c100009.m1982


----------



## GreenNeedle

Well the Zalytron "not bad boy" arrived and on the same day the Brimar came.  Both are 6SN7GT.  That brings me to 4 6SN7 variants now as I also have a Wards Airline 6SN7GTB and a Tung Sol* 6SN7GT. *This is identical to the one in post 108 of this thread which was identified as Raytheon made....so I'll call it Ray-Sol.  All paired with a Tung-Sol 5998

The Ray-Sol does sound nice.  I am quite fond of the sound from the Mazda 12AU7 (I bought a bundle of them after hearing the first one) and the Ray-Sol is pretty similar.  Maybe a little more body.  It is a little bit shorter than the Zalytron but not by much.  Nice sounding tube

The Wards Airline is much shorter.  Shortest of the 4.  It does sound pleasant but has noticeable rolled off top end.  Bass isn't as punchy as the Ray-Sol.  I daresay the 5998 is helping this sound better than it is 

And so in went the Zalytron.  Quite excited.  Probably shouldn't have put Marillion on but then they are my fav band.  The Bass that people talk about is there, The treble is quite nice but the mids are not for me.  The upper mids can get a little shouty and sometimes vocals with effects can feel like they are on top of you.  Yes this was a 10 minute test.

Disappointed I put the Brimar in and instantly was wowed.  This is exactly the sound I like and as lush as can be.  Handles those upper mids much better.  Deals with congestion (Newer Marillion gets terribly congested in the mids) very well.  Bass punchy without being overwhelming.  Treble has nice extension.

I've cycled through the 3 (ignoring the Wards Airline) and am not really getting on with the Zalytron at all.  Maybe it needs some time .  Maybe it has never been burned in?  Maybe it is knackered?  Maybe it just isn't what I like in a tube's sound.

So I sit here now listening to Pearl Jam - Ten with my new love, the Brimar.  I'll take some pics of the Zalytron when I get a chance for you guys to see what you think:


----------



## Ripper2860

It's quite easy to be smitten by a Brimar 6SN7GT.  Welcome to your new addiction!


----------



## Ranger Ron

GreenNeedle said:


> Well the Zalytron "not bad boy" arrived and on the same day the Brimar came.  Both are 6SN7GT.  That brings me to 4 6SN7 variants now as I also have a Wards Airline 6SN7GTB and a Tung Sol* 6SN7GT. *This is identical to the one in post 108 of this thread which was identified as Raytheon made....so I'll call it Ray-Sol.  All paired with a Tung-Sol 5998
> 
> The Ray-Sol does sound nice.  I am quite fond of the sound from the Mazda 12AU7 (I bought a bundle of them after hearing the first one) and the Ray-Sol is pretty similar.  Maybe a little more body.  It is a little bit shorter than the Zalytron but not by much.  Nice sounding tube
> 
> ...


----------



## highstream

Speaking of Brimar, I’ve been listening to a newly arrived 1578 pair for the past several hours that had been burned in for a few days, but it wasn’t until putting in a Brimar 5R4GY rectifier that the Melz came alive a sense of presence and warmth. Until then, the Melz was clear and rhythmic — and as dry and thus emotionally distant as could be. It’s still there a little, though it has good clarity and spatial presentation.


----------



## shafat777

Ive been using my Feliks Audio elise for about a month now. So far, this amp rocks. However i think its time for me to dive head first in the world of tube rolling. For starters I have a pair of 6as7g RCA black plate power tubes. Driver tubes, for now, are PSVane cv-181 T mk2. This combo is decent as it gives me plenty of bass while maintaining a good balance of mids and highs. However, the bass is boomy and not very controlled and not very punchy, which in returned casts a veil over the mids and vocals. 

Can anyone plz recommend me some 6sn7 tube or variants that will play well with my RCA 6as7gs. The PS vane is good but i want to bring out the best out of my Elise. 

I mostly use my ZMF VC and Auteur with my Elise. Any help would be appreciated.


----------



## JKDJedi

Got a pair of 53' 6H8C the other day, any idea what the* M* stamp signifies?


----------



## Ripper2860 (Dec 2, 2020)

Russian categorization stamp.  M stands for* M*ediocre grade classification.


----------



## JKDJedi

Ripper2860 said:


> Russian categorization stamp.  M stands for* M*ediocre grade classification.


----------



## bcowen

Ripper2860 said:


> Russian categorization stamp.  M stands for* M*ediocre grade classification.



Your Russian is a little rusty.  M stands for *M*agnificent. Like me.


----------



## JKDJedi

bcowen said:


> Your Russian is a little rusty.  M stands for *M*agnificent. Like me.


----------



## Tom-s

Help me identify this 6SN7. All RCA licensed 6SN7's look the same to me. I think this tube could be made in any RCA factory. Experts please chime in. 

I got this tube, based on it's box. No text on the tube/base other than standard RCA markings. Test as NOS. Looks new. Came without any wrapping or packaging material in the box. The box says 6SN7GT as does the tube. The bottom is a RCA licensed bottom. Internally it has a bottom D getter. Copper grip support rods. Spot welded black plates. Twisted heater wire. The plate press left a central dot in the middle of each "square" on the plates, no vertical nor horizontal lines on the plates (like some RCA's from other factories). 

Could anyone match this tube to their own Italian Marconi 6SN7GT? Does it look the same? Differences?


----------



## mayurs

I was told in the other big 6sn7 thread that this Sylvania 6sn7gt Vt-231 is actually a Brimar tube seeing its construction. Anyone has any idea about this tube sounds? I will be using on my Feliks Euforia. I haven't seen this type of a Sylvania VT-231 even in pictures any where. Are they rare or what?


----------



## JKDJedi

mayurs said:


> I was told in the other big 6sn7 thread that this Sylvania 6sn7gt Vt-231 is actually a Brimar tube seeing its construction. Anyone has any idea about this tube sounds? I will be using on my Feliks Euforia. I haven't seen this type of a Sylvania VT-231 even in pictures any where. Are they rare or what?


@therremans just got a pair of these Brimars. I got a KenRad VT-231 with Sylvania construction...lol... so yeah, all kinds of tube swapping going on back then.


----------



## therremans (Feb 12, 2021)

therremans said:


> *Brimar 6SN7GT*
> 
> 
> 
> ...


----------



## highstream

I can’t tell the dates, but during the wars, WWII and Korean, the demand led to companies pooling resources. While Sylvania much later merged with Osram and is now part of a Chinese company, back then I think it was an independent U.S. company, while the Brimar name stood for BRItish Made American Range tubes. So maybe there’s the crossover, with Brimar helping supply the US military, especially its air force flying out of England.


----------



## Greendriver

West German. Possibly Sovtek? Saucer (getter?) near the base...


----------



## Ranger Ron

Greendriver said:


> West German. Possibly Sovtek? Saucer (getter?) near the base...


How does it sound?


----------



## Greendriver

I love the sound. Very balanced and full of detail.


----------



## mayurs

Did Sylvania make a brown base VT-231 6SNGT. Could not find any info on this particular tube. I have only seen black Sylvania Vt-231s so far and all brown bases I have seen are 6SNWGT tubes.


----------



## cddc

Greendriver said:


> West German. Possibly Sovtek? Saucer (getter?) near the base...




This is a Russian Foton 6N8S, most likely made in 60s or 70s.


----------



## cddc

mayurs said:


> Did Sylvania make a brown base VT-231 6SNGT. Could not find any info on this particular tube. I have only seen black Sylvania Vt-231s so far and all brown bases I have seen are 6SNWGT tubes.




I've never seen brown base Sylvania VT-231, this one is actually a Sylvania 6SN7WGT or 6SN7WGTA.


----------



## JKDJedi

cddc said:


> This is a Russian Foton 6N8S, most likely made in 60s or 70s.


I concur... Russian made tube. 👍


----------



## cddc (Mar 5, 2021)

Tom-s said:


> Help me identify this 6SN7. All RCA licensed 6SN7's look the same to me. I think this tube could be made in any RCA factory. Experts please chime in.
> 
> I got this tube, based on it's box. No text on the tube/base other than standard RCA markings. Test as NOS. Looks new. Came without any wrapping or packaging material in the box. The box says 6SN7GT as does the tube. The bottom is a RCA licensed bottom. Internally it has a bottom D getter. Copper grip support rods. Spot welded black plates. Twisted heater wire. The plate press left a central dot in the middle of each "square" on the plates, no vertical nor horizontal lines on the plates (like some RCA's from other factories).
> 
> Could anyone match this tube to their own Italian Marconi 6SN7GT? Does it look the same? Differences?




Hahah, you never gave easy questions, Tom. 

I'm not so familiar with European tubes, so I'd venture a guess here 

This is definitely a very confusing tube. If memory serves, RCA licensed some Italian manufacturers to produce 6SN7 tubes, I forgot the names, possibly ATES or Sicte. I have seen some ATES or Sicte 6SN7 tubes that are quite similar to RCA 6SN7's in construction. So it's hard to say if this tube was made by Ates/Sicte or RCA, but the top mica seems so RCA to me that I would guess it's 90% an RCA tube.

You can also give the tube a listen to see if it sounds like an RCA or different.

Edit: BTW, the stop sign 6SN7GT etched on the glass also seems so American.


----------



## Greendriver

JKDJedi said:


> I concur... Russian made tube. 👍



Thanks for the info. Can't explain why it sounds so good. Using BeyerDynamic DT1990 PRO.


----------



## cddc

Greendriver said:


> Thanks for the info. Can't explain why it sounds so good. Using BeyerDynamic DT1990 PRO.




I guess that's mainly because you have a nice Mullard 6080 sitting in the power tube seat.


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## cddc

Ripper2860 said:


> Russian categorization stamp.  M stands for* M*ediocre grade classification.




I'd initially guess M stands for *M*ilitary, but then google translator told me Military spells as "военный", so now I have to believe M stands for *M*ediocre...LOL


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## Greendriver

cddc said:


> I guess that's mainly because you have a nice Mullard 6080 sitting in the power tube seat.


Also have a Sylvania which I had to take out because of the loud cracking on one channel. I have a Brimar 6080 in   the pt seat now, which is softer in nature...


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## Ranger Ron

Greendriver said:


> Also have a Sylvania which I had to take out because of the loud cracking on one channel. I have a Brimar 6080 in   the pt seat now, which is softer in nature...


Try soldering the pins of the sylvania.


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## bcowen

Ranger Ron said:


> Try soldering the pins of the sylvania.


Yup.  +1 on that.


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## mayurs

Need a positive ID of another RCA tube that my tube dealer has sent. I am unable to identify or see any other RCA 6sn7 of this type any where.


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## therremans (May 17, 2021)

Deleted


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## tubebuyer2020 (May 17, 2021)

(deleted due to immediately above being deleted)


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## Ranger Ron

mayurs said:


> Need a positive ID of another RCA tube that my tube dealer has sent. I am unable to identify or see any other RCA 6sn7 of this type any where.





mayurs said:


> Need a positive ID of another RCA tube that my tube dealer has sent. I am unable to identify or see any other RCA 6sn7 of this type any where.


Fascinating tubes you have there. The top looks similar to a grey glass National Union. Are the plates flat ladder style?


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## tubebuyer2020

@therremans what is this secrecy, did you find a "deposit" of tubes for $1 each ?


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## Ripper2860

Deleted

Deleted x2

I'll see your DELETION and raise you 2 DELETIONS!


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## mayurs

Ranger Ron said:


> Fascinating tubes you have there. The top looks similar to a grey glass National Union. Are the plates flat ladder style?


Here is the NU top picture. Those loops seem to be in opposite direction compared to the same direction on those unknown RCAs.


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## therremans

tubebuyer2020 said:


> @therremans what is this secrecy, did you find a "deposit" of tubes for $1 each ?


Seller sent me photos of the tube and it was in fact a Raytheon. However it wasn’t the same tube shown in the photo that reveals its upper round mica. So I assume they mixed it up with another they had.


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## Ranger Ron

mayurs said:


> Here is the NU top picture. Those loops seem to be in opposite direction compared to the same direction on those unknown RCAs.
> 
> 
> mayurs said:
> ...


----------



## attmci

mayurs said:


> Need a positive ID of another RCA tube that my tube dealer has sent. I am unable to identify or see any other RCA 6sn7 of this type any where.


How do u like the tube? It should sound better than a TS BGRP. Buy all from the dealer.


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## mayurs (May 18, 2021)

attmci said:


> How do u like the tube? It should sound better than a TS BGRP. Buy all from the dealer.


I have not bought them yet, you think they are worth buying?

Is this the TS BGRP ?


----------



## Varejao17

Off topic alert:  an electrical engineer friend of mine has a very old German T-1 triode that is planar in construction (but it's not a "planar triode" in the later usage of that term.)  Thought you all would get a kick of out seeing it:


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## Ripper2860

Cool!  Any idea how old 'really old' is?


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## Varejao17 (May 20, 2021)

Ripper2860 said:


> Cool!  Any idea how old 'really old' is?


Not entirely sure, but some documentation suggests pre-1925...
https://www.radiomuseum.org/tubes/tube_t1_tkd.html


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## ChrisPDX (Oct 15, 2021)

adhoc said:


> The 6SN7GTA and GTB versions were introduced in 1950 and 1954 respectively. They have ‘upgraded’ ratings, which are as follows.
> 
> GTA: maximum anode dissipation upgraded to 5W (the GT is rated for 2.5W)
> GTB: identical to the GTA, but with a controlled heater warm up time for use in equipment with 600mA heater strings
> ...


This last paragraph above (highlighted in red) is quite concerning.

My Schiit Freya+ shipped with Tung-Sol 6SN7*GTB *tubes.

Yet the owner’s manual clearly indicates: “Freya+ accommodates *any 6SN7*, 6N8S, or 5692 tube type.”

*Am I to believe that Schiit is simply unaware that using a 6SN7GT tube in their Freya+ pre-amp *_— _which evidently has a circuit designed around the 6SN7GTA/GTB tubes that they provided with it —* will actually rapidly destroy and possibly damage my new Schiit pre-amp?*

Surely Schiit engineers are not guiding their customers towards tubes that will destroy their products, right ?  Am I  misunderstanding what @adhoc meant ? Or is his warning incorrect ?

Thanks. I like this thing and do not want to rapidly destroy it by following its manufacturer’s guidance.


----------



## JKDJedi

ChrisPDX said:


> This last paragraph above (highlighted in red) is quite concerning.
> 
> My Schiit Freya+ shipped with Tung-Sol 6SN7*GTB *tubes.
> 
> ...


None of those tubes ever reach to their max potential when used for audiophile purposes.. your good.


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## tafens

ChrisPDX said:


> This last paragraph above (highlighted in red) is quite concerning.


It’s definitely something to be aware of and cautious about.

The 6SN7GTA/GTB is designed to handle up to 450V on the plates, while the GT is only designed to handle max 300V.



ChrisPDX said:


> My Schiit Freya+ shipped with Tung-Sol 6SN7*GTB *tubes.
> 
> Yet the owner’s manual clearly indicates: “Freya+ accommodates *any 6SN7*, 6N8S, or 5692 tube type.”
> 
> ...



The warning is absolutely correct, you don’t want to exceed the maximum plate voltage. Nasty things may start to happen if you do.

However, with the Freya+, as the manual states, you are good to go with any 6SN7 tube, which means that they won’t exceed 300V on the plates (or indeed the lowest voltage of all of the tube type that the manual lists, and probably go a fair bit lower than that, too, to conserve tube life).

it just happens to ship with GTB:s, probably because 1) they think they sound best, or 2) they’re easy to find in bulk, or 3) both


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## Ripper2860 (Oct 16, 2021)

Jason, Mike, and team are pretty smart cookies, so I'm confident that they know what they are doing.  Plus, it has a 5 year warranty, so they must feel pretty OK with GTBs being in their gear seeing as they shipped it that way.


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## bcowen

tafens said:


> *it just happens to ship with GTB:s, probably because 1) they think they sound best, or 2) they’re easy to find in bulk, or 3) both *



Exactly.  Just because the amp _shipped_ with GTB's doesn't mean it _requires_ GTB's.


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## JKDJedi

bcowen said:


> Exactly.  Just because the amp _shipped_ with GTB's doesn't mean it _requires_ GTB's.


Mr Bcowen here is the Schiit Magnet (meant that in a nice way) .. he'll set you straight.


----------



## ChrisPDX

bcowen said:


> Exactly.  Just because the amp _shipped_ with GTB's doesn't mean it _requires_ GTB's.





JKDJedi said:


> Mr Bcowen here is the Schiit Magnet (meant that in a nice way) .. he'll set you straight.


Thanks all for the responses and reassurance that Schiit knows what they’re doing, as I had assumed, and that I will not destroy my pre-amp by following their guidance.

In a thread purporting to be an authoritative guide to 6SN7 tubes on an audio-playback forum, the unqualified statement quoted is at best incomplete, at worst misleading. I hope @adhoc will consider revising it to avoid raising unnecessary concerns.

Thanks again for the insights, all.


----------



## bcowen

ChrisPDX said:


> Thanks all for the responses and reassurance that Schiit knows what they’re doing, as I had assumed, and that I will not destroy my pre-amp by following their guidance.
> 
> In a thread purporting to be an authoritative guide to 6SN7 tubes on an audio-playback forum, the unqualified statement quoted is at best incomplete, at worst misleading. I hope @adhoc will consider revising it to avoid raising unnecessary concerns.
> 
> Thanks again for the insights, all.


No offense, but there is nothing incorrect or misleading about @adhoc 's statement.  Basically, don't put a GT in a component that is designed for the higher voltages of a GTA or GTB and therefore _requires_ a GTA or GTB to function correctly.  Any credible component manufacturer would make this requirement quite clear in the manual or otherwise.  Every audio component I've ever used has been designed around a GT.  I can use a GTA or GTB without issue of course, but they aren't required.  Your Schiit was also not designed to require a GTA or GTB -- it was designed for a GT.  Perhaps Schiit caused unnecessary confusion by sending yours with a GTB tube, but that doesn't invalidate what @adhoc wrote.


----------



## ChrisPDX

bcowen said:


> No offense, but there is nothing incorrect or misleading about @adhoc 's statement.  Basically, don't put a GT in a component that is designed for the higher voltages of a GTA or GTB and therefore _requires_ a GTA or GTB to function correctly.  Any credible component manufacturer would make this requirement quite clear in the manual or otherwise.  Every audio component I've ever used has been designed around a GT.  I can use a GTA or GTB without issue of course, but they aren't required.  Your Schiit was also not designed to require a GTA or GTB -- it was designed for a GT.  Perhaps Schiit caused unnecessary confusion by sending yours with a GTB tube, but that doesn't invalidate what @adhoc wrote.


No offense taken. Now, I’m obviously not an expert on this stuff, but it seems straightforward to conclude that, given the audio-playback context of this forum, the unqualified declaration that  “substituting a GT in place of a GTA/GTB in your equipment will precipitate its rapid destruction and possibly damage your equipment” is insufficiently complete, assuming of course that this forum is at least partly intended to assist relative beginners. Thanks again.


----------



## bcowen

ChrisPDX said:


> No offense taken. Now, I’m obviously not an expert on this stuff, but it seems straightforward to conclude that, given the audio-playback context of this forum, the unqualified declaration that  “substituting a GT in place of a GTA/GTB in your equipment will precipitate its rapid destruction and possibly damage your equipment” is insufficiently complete, assuming of course that this forum is at least partly intended to assist relative beginners. Thanks again.


I guess I wasn't reading it the way you were.  But I see your point now.  Perhaps it could be clarified into "substituting a GT in a component designed for a GTA/GTB will precipitate its rapid destruction and possibly damage your equipment."


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## Ripper2860 (Oct 16, 2021)

A most civil and enlightening last few posts.  Thank you for exhibiting patience and civility while  providing meaningful and knowledgable dialog.  There was certainly opportunity for the OP to be lambasted with mean and unhelpful posts, but the high ground was maintained.  Kudos to all involved.  You have shown why this is such a great community.

Time for tunes.  😀


----------



## PoloJCP

tafens said:


> It’s definitely something to be aware of and cautious about.
> 
> The 6SN7GTA/GTB is designed to handle up to 450V on the plates, while the GT is only designed to handle max 300V.
> 
> ...


I don't have a Freya+, I only have 2 Schiit Lyr3, which according to Schiit's official website and manual that it takes "6SN7". I have used them with GT/GTA/GTB and without any issues at all.


----------



## lostrockets (Apr 14, 2022)

.


----------



## JTbbb

Maybe there is not enough to see but, could this be a real B65?


----------



## RobertSM

JTbbb said:


> Maybe there is not enough to see but, could this be a real B65?


Looks real to me!


----------



## lupoal

Hi,
what do you think about these RCA ? I don’t understand the numbers printed … 57 - 30 mean year 1957 and week 30? but didn’t the production of this type RCA stopped in 1949?


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## JKDJedi

lupoal said:


> Hi,
> what do you think about these RCA ? I don’t understand the numbers printed … 57 - 30 mean year 1957 and week 30? but didn’t the production of this type RCA stopped in 1949?


Send them to me for further investigation please.


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## lupoal

… sure


----------



## Tom-s

Here's a fun tube to identify:
What am I?


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## TLO (Jul 30, 2022)

Tom-s said:


> Here's a fun tube to identify:
> What am I?


STC/Brimar CV1988?
Another pic of the top?

Edit: I could be wrong becos I dont think there are rings for the supporting rods from this angle.
Send it over, I will perform a surgical procedure and let you know...


----------



## bcowen

Tom-s said:


> Here's a fun tube to identify:
> What am I?


I'm pretty sure it's a 6SN7.  Is there a prize for guessing right?   🤣 🤣


----------



## JKDJedi

Tom-s said:


> Here's a fun tube to identify:
> What am I?


More important...how's it sound?


----------



## TLO

bcowen said:


> I'm pretty sure it's a 6SN7.  Is there a prize for guessing right?   🤣 🤣


yeah, a year of free supply of GE tubes at the discretion of @Tom-s...


----------



## bcowen

TLO said:


> yeah, a year of free supply of GE tubes at the discretion of @Tom-s...


Nah, that would be the punishment for guessing wrong.   🤣


----------



## jonathan c

The real punishment would be if the GE tubes had to be paid for…😳😮…


----------



## Tom-s

New photo. This tube has been discussed a few times before in this thread. Without any pictures as they are very rare.


----------



## TLO (Aug 1, 2022)

Tom-s said:


> New photo. This tube has been discussed a few times before in this thread. Without any pictures as they are very rare.


CV..KB..British made...hmmm
https://www.whatsbestforum.com/threads/mullard-6sn7gt-help-please-info-needed.15277/
https://www.stereonet.com/forums/to...-geeks-prove-your-tube-knowledge-superiority/

Mullard CV1988 / 6SN7GTY???...super rare


----------



## RickyV

Hi,

I am new to tubes and have a question. My amp uses one new Tung-sol 6sn7GTB in the input and I like replace with a NOS tube. So from what I have read is that I can’t replace it with a 6SN7GT because of the lower plate voltage. So before I knew that I inquired about this tube : 6SN7GT - VT-231 JAN Sylvania. It was the nicest 6sn7 tube he had. Later I learned GT can’t replace GTB’s and so I ask him again and that it was to replace a GTB but he still mentioned the same tube.

So now I am confused can the 6SN7GT - VT-231 JAN Sylvania, blackplate clearglass, bottom getter, medium glass envelope replace a 6sn7GTB????


----------



## JKDJedi

RickyV said:


> Hi,
> 
> I am new to tubes and have a question. My amp uses one new Tung-sol 6sn7GTB in the input and I like replace with a NOS tube. So from what I have read is that I can’t replace it with a 6SN7GT because of the lower plate voltage. So before I knew that I inquired about this tube : 6SN7GT - VT-231 JAN Sylvania. It was the nicest 6sn7 tube he had. Later I learned GT can’t replace GTB’s and so I ask him again and that it was to replace a GTB but he still mentioned the same tube.
> 
> So now I am confused can the 6SN7GT - VT-231 JAN Sylvania, blackplate clearglass, bottom getter, medium glass envelope replace a 6sn7GTB????


yes it can, and congrats.


----------



## chef8489

Those are great tubes and will sound much better.


----------



## RickyV

JKDJedi said:


> yes it can, and congrats.



Thanks that is good news but why? Is the 6sn7gt V-231 different then other gt’s?


----------



## TLO

RickyV said:


> Hi,
> 
> I am new to tubes and have a question. My amp uses one new Tung-sol 6sn7GTB in the input and I like replace with a NOS tube. So from what I have read is that I can’t replace it with a 6SN7GT because of the lower plate voltage. So before I knew that I inquired about this tube : 6SN7GT - VT-231 JAN Sylvania. It was the nicest 6sn7 tube he had. Later I learned GT can’t replace GTB’s and so I ask him again and that it was to replace a GTB but he still mentioned the same tube.
> 
> So now I am confused can the 6SN7GT - VT-231 JAN Sylvania, blackplate clearglass, bottom getter, medium glass envelope replace a 6sn7GTB????


Yes n no, if an amp has a circuit designed with GTB in mind with higher voltage to the plate of the 6SN7, you MAY kill the GT generation tube prematurely, however, it is very common nowadays that manufacturers design their circuit based on the GT biased voltage but use the later GTB due to supply availability and cost. Best approach is ask the manufacturer of your tube amp.


----------



## bcowen

RickyV said:


> Thanks that is good news but why? Is the 6sn7gt V-231 different then other gt’s?


Probably not.  The VT-231 is a military designation meaning that there were certain specs and/or selection standards that the tube had to meet.  Nobody knows for sure, but it's probable that tubes designated as VT's were made on the same assembly line at the same time as a tube that's marked as a 6SN7-GT.  There is no electrical difference between any other GT tube and the VT-231.


----------



## JKDJedi

RickyV said:


> Thanks that is good news but why? Is the 6sn7gt V-231 different then other gt’s?


Most are the same, as mentioned above V231 is just a military designated number. There are a few exceptions. Very few.


----------



## Chudyin

Hi everyone,

As a new owner of ANK KIT1 (with little knowledge about tubes yet) he completes a set of tubes for it.
Can you help what model Sylvania this is?
It looks like Bad Boy but has VT231 military print. So it's probably not from the 51-53s.
So the question is will it have its musical qualities?







Thanks for the help


----------



## rosgr63

Looks like the rate and great sounding Bad Boys
Is there a number on the side?


----------



## Ripper2860

Looks like a bad boy to me.  My tip is to always look at the tube characteristics/construction as the key identifier.  Tubes are MFG'ed and later mounted onto bases which are mfg'ed separately.  There have been cases where tubes were mounted on a base that was not necessarily applicable to the tube -- especially at the end of a MFG run of one type where there were surplus bases remaining for the prior tube.


----------



## JKDJedi (Dec 28, 2022)

Chudyin said:


> Hi everyone,
> 
> As a new owner of ANK KIT1 (with little knowledge about tubes yet) he completes a set of tubes for it.
> Can you help what model Sylvania this is?
> ...


Bad Boys are usually a little taller than the (normal 6SN7GT) but this will for sure sound like one (looks like one from here),, Like mentioned above, what's the date print on those, should be on the other side. (Might have to send that to me for further evaluation. 
April 28, 1952[edit]​The Treaty of San Francisco ends the US and the British Commonwealth's state of war with Japan.


----------



## Chudyin (Dec 28, 2022)

Thank you for you prompt reply. Most appreciate.

Apparently there is no date imprint on the base :/
I'm trying to get more pictures from the seller... but it's not cooperating


----------



## Ripper2860

FWIW -- I don't think I've ever seen a Sylvania VT-231 with the spiked top mica and 3-hole plates.  They usually have the same rounded-rectangle top and bottom mica and 2-hole plates.


----------



## JKDJedi (Dec 28, 2022)

Ripper2860 said:


> FWIW -- I don't think I've ever seen a Sylvania VT-231 with the spiked top mica and 3-hole plates.  They usually have the same rounded-rectangle top and bottom mica and 2-hole plates.


Good call @Ripper2860 looked up my archived photos of mine and yup... not VT-231


----------

