Versions the ECC83/12AX7 comes in are:

• ECC83/12AX7, ECC83 and 12AX7 are exactly the same, 12AX7 is the USA name and ECC83 is the name used in Europe. The ECC83 can be found in 14mm (normal) and 17 mm plate versions. The 17 mm are preferred by Audiophiles. The 14 mm version made by Mullard sometime have the box-plates. The 17 mm versions can have ribbed and smooth plates. The ECC83/12AX7 can only be used in parallel heater applications.
• The CV492 is a special version of the ECC83 made by many manufacturers. This tube is often referred to as the best sounding tube.
• 12AX7A is the same as the ECC83/12AX7, except they can also be used in series heater applications
• The 7025 is the low noise industrial version. It has spiral wounded heater wires to reduce hum and noise. These can be used very well in high-demanding audio applications.
• The E83CC or 12AX7WA, 6681 and the English special versions CV4004, M8137, 6932, 7242 and 6057 are premium military and industrial versions of the ECC83/12AX7. These tubes are made for long life and can withstand a lot of on/off cycles. They also are extra ruggidised and sometime have triple mica.
• The B759 is a ultra-low noise version of the 12AX7, with matched triode elements. These types were only made in England by Genalex (Marconi-Osram Valve Co.)
• The 5751 is the "milspec" version of the 12AX7. It has sligthly lower gain than the ECC83 (70 against 100), but this also reduces hum and noise. The 5751 comes in many versions. There are black plates, double and triple mica version and some have extra support rods. The triple mica version have three mica support layers and this reduces microphonics.
• 7729 is the premium instrument grade tube made only by CBS/Hytron. This tube has heavily plated gold pins.
• CV4035 is a flying leads very special quality version of the ECC83. Most problems arise in the pin/socket connection, so this tube is made to be soldered directly into the circuit. Also internal it is made to highest low noise and microphonics specifications, very special tube!
• ECC803(S) is the premium version of the European ECC83. These tubes were made and tested for low microphonics and low noise. The "S"-version is specially selected for low noise.
• The E283CC is a very special quality ECC83/12AX7. As good sound as the famous ECC803S made by Telefunken, it also hase a frame grid. It has different pinout (shielding between both sections), but is electrically equal. It is easy and worthwile to make the modification!
• The ECC808/6KX8 is a very low noise ECC83/12AX7 replacement. It has different pinout (symmetrical build up and shielding between both sections), and has lower maximum platedissipation (0.5W against 1W). When you need very low noise and high channel rejection, this type is the best choice.
• 6H2pi or 6N2pi, Russian near equivalent of the 12AX7 / ECC83. It has almost the same pinout, but has 6.3 V heating on pins 4 and 5. Pin 9 is connected to a shield between both triodes. The 6H2n has slightly higher gm then the 12AX7 / ECC83, giving it more power and authority than the 12AX7 / ECC83.

5751

Type	Description	State	Brand	Number in stock	Price each (Euro)
5751	Grey plates with extra support, getter shield, made in U.S.A (GE)	NEW	Heinz Kaufman Gammatron	1	32.50
5751	Black plates, extra support rods, O-getter, made in U.S.A.	NEW	Burroughs	1	32.50
JAN 5751	Grey plates, green text, O-getter, double thick mica, dated 1979-1980	NOS	GE picture	4 single 17 pair	19.50 44.00 (pair)
JAN 5751	Grey plates, green text, O-getter, dated 1970's.	NOS	GE	4 single 1 pair	19.50 44.00 (pair)
JAN 5751	Grey plates, green text, O-getter, copper grid rods, dated 1974	NOS	Sylvania	1	19.50
5751	17 mm long plates, D-getter, no visible label, testing good	USED	???	1	14.50
5751	Triple mica, O-getter, extra support, testing good	USED	GE	1	14.50

ECC83/12AX7(A)

Type	Description	State	Brand	Number in stock	Price each (Euro)
ECC83	O-getter, 17 mm long plates, Siemens mC factory codes, in original cases	NOS	Siemens	3	54.00
ECC83	O-getter, 17 mm long plates, Siemens mCp factory codes	NEW	Labelled Philips Miniwatt	1	44.00
ECC83	O-getter on double rods, 17 mm long plates, testing good	USED	Siemens	1	24.00
ECC83	O-getter on double rods, made in Germany, in original case, Siemens factory codes	NOS	Labelled Lorenz	1	35.00
ECC83 / 12AX7	O-getter on double rods, Labelled Microline, made in Germany	NEW	Siemens	1	29.00
12AX7	Stapeled plates, O-getter, triple mica, very faint European factory code, probably E83CC made by Siemens (looks very much like them). Internally matched	NEW	Labelled 12AX7	1	37.00
12AX7	Small O-getter, Philips Heerlen I65 datecodes	NOS	Philips	2 pairs	139.00(pair)
ECC83	O-getter	NOS	Philips	1	28.00
ECC83	O-getter, made by Philips Canada (Canada factory code)	NEW	Philips Miniwatt	1	24.00
ECC83	Disk-getter, Labelled Geloso Milano Italy	NOS	Philips picture	1 pair	45.00 (pair)
ECC83	Mc3 date code, O-getter, testing very good	USED	Philips Miniwatt	1	28.00
ECC83	O-getter, made by Philips Heerlen, Labelled "HP, by Amperex, made in Holland". Testing very good	USED	Labelled HP/Amperex	1	18.00
ECC83	17 mm stapeled plates, O-getter, made in Yugoslavia (factory codes)	NOS	Labelled Siemens Labelled Philips	1 1	27.00
ECC83	Has the metal stamped clip, extra support rods, welded plates, O-getter on double support. Labelled "Industria ECC83", in white case from factory batch packing	NOS	Tungsram picture	4 single 33 pair	19.50 48.00 (pair)
ECC83	Small plates like ECC81, extra support, O-getter, in Tesla ECC83 original boxes	NOS	RFT picture	4 pair	39.00 (pair)
ECC83	Small plates like ECC81, extra support, O-getter, in white case from factory batch packing	NOS	RFT picture	5 single 2 pair	16.50 39.00 (pair)
12AX7	Triple mica, O-getter	NEW	???	1	32.00
ECC83	17 mm ribbed plates, O-getter	NEW	???	1	24.00
ECC83	O-getter	NOS	RSD	1	19.00
JG-12AX7	17 mm ribbed plates, D-getter, internally matched	NEW	GE	1	36.00
JRP-12AX7	O-getter, In box dated 1963, similar to the CV-492	NOS	Raytheon	1	36.00
JHS-12AX7	17 mm ribbed plates, O-getter, In box dated 1961, similar to the CV-492	NOS	Sylvania	1	31.00
12AX7	17 mm plates, O-getter, yellow label	NEW	Sylvania	1	26.00
12AX7	17 mm plates, O-getter, made in Italy under RCA license	NOS	Labelled ATES	1	26.00
12AX7A	O-getter, red label, HP costumer service boxes, Sanborn 69A-4.	NOS	HP	1	26.00
ECC83S	Very nice tube, good sound for the money. Frame grid construction like the ECC803S Telefunken, no label, from factory batch box	NNP	JJ Electronics	8 single 62 pair	9.00 19.50 (pair)

E283CC

Type	Description	State	Brand	Number in stock	Price each (Euro)
E283CC	O-getter, triple mica, very extended shielding in base, Siemens factory codes. Adzam label and original boxes	NOS	Made by Siemens SQ image	1 single 2 pairs	34.00 85.00 (pair)
E283CC	Special quality tube, no labels, made by Siemens	NEW	Siemens	2	28.00
E283CC	Special quality tube, made by Siemens, testing very good	USED	Siemens	1	18.00

CV4035

Type	Description	State	Brand	Number in stock	Price each (Euro)
CV4035	Very special quality low noise and microphonics flying leads ECC83 version, made by Brimar (England). Internally matched	NOS	Valve electronic picture	2	45.00

E83CC, 12AX7WA

Type	Description	State	Brand	Number in stock	Price each (Euro)
JAN 12AX7WA	17 mm grey plates, O-getter, green text	NEW	Sylvania	1	38.00
JAN 12AX7WA	17 mm grey plates, O-getter, green text, testing good at 1.2/1.1 and 1.2/1.4 mA	USED	Sylvania	1 pair	78.00 (pair)
JAN 12AX7WA	Grey plates, O-getter, green text	NOS	GE	1 pair	78.00 (pair)
12AX7WA	O-getter on double support, copper grid rods, double mica, probably made by Tungsram	NOS	Labelled Teonex	1 pair	68.00 (pair)
12AX7WA	O-getter on double support, copper grid rods, double mica, probably made by Tungsram. Internally matched	NOS	Labelled Teonex	3	32.00
12AX7WA	O-getter on double support, copper grid rods, double mica, probably made by Tungsram	NOS	Labelled Teonex	2	28.00

CV492

Type	Description	State	Brand	Number in stock	Price each (Euro)
CV492	D-getter directly on mica, 17 mm plates, testing 2.0/2.1 mA, like NOS, Delta6H datecodes	USED?	Philips	1	49.00
K1007 / CV492	17 mm long smooth plates, Made in Yoegaslavia, great sounding tubes, O-getter	NOS	Siemens picture	1	32.00

6H2pi

Type	Description	State	Brand	Number in stock	Price each (Euro)
6H2pi	Russian close version to ECC83. Very good sound compared to some of the cheaper NOS ECC83. Voskod factory logo	NOS	Russian NOS	6 single 22 pairs	2.90 7.50 (pair)

ECC808 / 6KX8

Type	Description	State	Brand	Number in stock	Price each (Euro)
ECC808	O-getter, Labelled Siemens, but Valvo factory codes. Internally matched	NOS	Siemens	2 single	39.00
ECC808	O-getter, Valvo factory codes	NOS	Labelled Tungsram	1	36.00
ECC808	O-getter, <> bottom, testing just good	USED	Telefunken	1	12.00

CV4004, M8137, 6932 and 6057

Type	Description	State	Brand	Number in stock	Price each (Euro)
CV4004 / M8137	O-getter, box plates, internally matched, 641 / R5D3 datecodes, shield logo	NEW	Mullard	1	89.00
CV4004	O-getter, Semi box plates, very faint label, internally matched	NEW	Probably Brimar	1	48.00

ECC803, ECC803S

Type	Description	State	Brand	Number in stock	Price each (Euro)
ECC803S	JJ version of this beautiful tube. Long plate anodes, very nice internal construction	NNP	JJ Electronics	2 single 4 pairs	11.95 24.90 (pair)

7729

None in stock at the moment, please check back soon

7025

None in stock at the moment, please check back soon

6681

None in stock at the moment, please check back soon

B759

None in stock at the moment, please check back soon