TUBES NOS NIB

 

Considered the exponential progression of the historic valves prices we believe we have to give more guarantees to investors in this particular segment.

Since the inception of the webshop all valves "new old stock" or "new in box" sold by Audiogears are tested and priced based on measured performance and matching.

From now on, this selection is pushed to the extreme level that the equipment in our possession allow us, and we believe we are the only worldwide retail outlet that offers the tubes with the system described below.

All tubes proposed by Audiogears will have a unique code that will allow us to locate them in time and retrieve the test done before the sale even after many years 

The results collected will be printed on a label on the box of each tube together the factory codes basic measures and the unique code Audiogears.

The tubes will be selected individually, in pairs or multiples, and all parameters will be reported online. The selection will be made by the method which you can read below. The photos will refer ALWAYS commissioning tube for sale. Basically what you see in the image will be what you are really buying.

The expenditure of time is huge but we believe it's worth it. The valves from Audiogears definitely cost a few euro more than the competition, but you will have the absolute guarantee that you are going to buy. 

To better relate to our competitors we made sample purchases both by the most popular eBay resellers who by the most accredited independent competitors and we had incredible surprises, in the negative. 

Of course in the description you can see the year of production (where this can be determined) and the actual tube manufacturer which is not always the brand printed on the glass. 

Proposals tubes are all NEW and classified as NOS (new old stock) or NIB (new in box) the difference among these is the presence of the original box (NIB) or not (NOS)

There may be some cases where, since the extreme rarity of the item, there is a certain degree of use, in this case also be clearly stated, whether it is virtually impossible to estimate the number of hours of use. 

To get a first idea of quality level it will be indicated under the initials of the tube the fundamental fact: the Mu for triode preamp and GM for the power tubes. Below we will see why. 

Then opening the valve page to which you are interested you will find all other parameters 

Method of tubes selection 

To proceed with the selection of the valve and matching we note the following parameters

transconductance

anodic emission 

plate Resistance

Gain 

microphonic 

also it is checked: 

Gas presence 

Loss of grid

 

almost all of historic valve retailers (exceptions can be counted on the fingers of one hand) proposed as a method of selection the only Ia: the anode emission. 

In fact this has a relative weight if linked to the matching process 

The reason that the Ia is the most widely used reference is that most of the sellers is equipped with tube testers able to give an indication of the type "good" or "bad" while in the best cases precisely detect the anodic current. 

Very few historians testers are capable to detecting the transconductance and as we will see later is a fundamental fact to derive a key value into pairs of preamp tubes: the Mu ie the gain.

Mu, Gm and Rp that is to say the basic parameters

 Mu (voltage gain), GM (transconductance) and Rp (plate resistance) are the three basic electrical characteristics for a vacuum tube. 

Mu is the product of two data: GM and Rp 

What does GM? incremental variation of plate current / incremental variation of the grid voltage to a specific working point and is the primary measure to detect the gain of the tetrodes and Pentodes. The GM decreases with the aging of the tube, is therefore an important fact to get a first rough idea of the fact that our valve is new or not (but is not an absolute certainty)

 TRIODES 

In triode two fundamental parameters: GM and Rp will produce a third Mu. These parameters are in a relationship such that knowing any two you will get the third. Just as Ohm's law. In the case of triodes, Mu = Gm x Rp. GM is measured in mhos, (micromohms) and Rp is measured in ohms between them is obtained by multiplying the MU, a Mu of 30 means that what enters the valve comes out in principle 30 times more great.

 Triodes are mostly used for voltage amplification in our preamplifiers. Here the Mu (voltage gain) is the most important parameter to be measured and the one that most directly effects what we're going to listen. 

 So let's say that if you get two triode combined using as a parameter the only GM there is no guarantee that these pipes will have an equal voltage gain. 

 But the Rp is hardly ever measured, the value that the passionate search is normally the anode output (Ia). Our tube tester, Amplitrex AT1000, can measure each parameter as those cited above we are therefore able to propose matched tubes and, in the case of double triode, with sections balanced as it should be. 

 Some famous tester, Hickock for example, are sought after for their ability to measure the Gm, but if it is not able to detect the Rp as well will not be possible to calculate the Mu with a simple multiplication. The reason that almost never gets the data from Rp valve suppliers is that it is difficult to measure, and with the old commercial tester has never disclosed this parameter. 

Many of you are buying pairs of tubes because the seller says they are matched, if you look on popular online sales sites or on ebay you will notice that almost all vendors offer their matchate valves only according issuance anode. Very very rarely you find Gm and practically never the MU 

then is FUNDAMENTAL into pairs of preamp tubes that, both the two inner sections (in the case of double triodes), and between the tube and tube there is a given Mu as similar as possible.

Typically in the case of the most thrusts selections this should be below the 5% 

Audiogears will put on sale the triode with MU values significantly unbalanced to the lowest figures of the average market value. Keep in mind that much of what you buy at full price by the majority of sellers does not take any account of this fundamental fact. 

PENTODES, tetrodes etc. 

The pentodes are an entirely different matter. For pentode, such as those used in the output stages of the amplifiers, the Gm is actually essential for good performance. So to match our pentodes we will have to rely on this data. 

Pentodes in the Rp assumes less importance as related to the output transformer. So the GM is the parameter to be considered in the matching But even in this case the old meters are not all'atezza of the situation because they can not detect this parameter (the few who are able to do so) under the actual working conditions to ' internal of the circuit.

Amplitrex once again is able to do so.

Couples or quartets that you will find here are paired taking as the main parameter precisely the transconductance.


Show more subcategories

 


GE 12BH7 A

Product code: NOS12BH0001

85,00

12BH7 A GE COPPIA

Mu 15.8-15.5 / 15.8-16.5

 


GE 12BH7 A

Product code: NOS12BH0002

60,00

12BH7 A GE COPPIA

Mu 16.5-16.3 / 17.5-18.3

 


GE 12BH7 A

Product code: NOS12BH0003

70,00

12BH7 A GE COPPIA

Mu 16.8-16.3 / 17.8-17.3

 


ATES-RCA 12BH7 A

Product code: NOS12BH0005

70,00

12BH7 A RCA ATES COPPIA

Mu 16.5-16.0 / 16.5-17.0

 


ATES-RCA 12BH7 A

Product code: NOS12BH0006

70,00

12BH7 A RCA ATES COPPIA

Mu 16.5-16.0 / 15.5-16.0

 


ATES-RCA 12BH7 A

Product code: NOS12BH0007

70,00

12BH7 A RCA ATES COPPIA

Mu 16.4-16.5 / 15.5-15.5

 


SYLVANIA 12BH7 A

Product code: NOS12BH0011

40,00

12BH7 SYLVANIA 

Mu 16.0-16.2

 


SELECTRON RCA 12BH7 A

Product code: NOS12BH0012

55,00

12BH7 SELECTRON RCA PAIR

Mu 15.2-15.3 / 15.2-16.6

 


PHILCO 12BH7A

Product code: NOS12BH0013

90,00

12BH7 PHILCO PAIR

Mu 16.7-15.8 / 16.3-16.9

 


MULLARD E188CC CV4108

Product code: NOS1880001

240,00

E188CC MULLARD pairMu 31.9-31.6 / 31.0-30.8 

 


MULLARD E188CC CV4108

Product code: NOS1880002

240,00

E188CC MULLARD pair

Mu 32.9-33.9 / 33.7-32.8

 


VALVO-PHILIPS E188CC

Product code: NOS1880010

250,00

E188CC VALVO-PHILIPS VR1

Mu 31.2-31.4

 


MARCONI 2A3

Product code: NOS2A0035

450,00

MARCONI 2A3 DUAL GETTER

GM uMhos : 5600-5700

 


MARCONI 2A3

Product code: NOS2A0036

400,00

MARCONI 2A3  DUAL GETTER

GM uMhos : 5150-5250

 


MARCONI 2A3

Product code: NOS2A0037

420,00

MARCONI 2A3  DUAL GETTER

GM uMhos : 5800-5700

 


MARCONI 2A3

Product code: NOS2A0039

350,01

MARCONI 2A3  DUAL GETTER

GM uMhos : 5300-5600

 


MARCONI 2A3

Product code: NOS2A0040

370,00

MARCONI 2A3 SINGLE GETTER

GM uMhos : 5450-5540

 


MARCONI 2A3 "ENGRAVED BASE"

Product code: NOS2A0041

500,00

MARCONI 2A3 "BLACK PLATE"GM uMhos : 5450

 


PHILCO 2A3

Product code: NOS2A0042

289,99

PHILCO 2A3 COPPIA

GM uMhos : 5250-5550

 


PHILCO 2A3

Product code: NOS2A0043

350,01

PHILCO 2A3 COPPIA

GM uMhos : 5800-5650

 


RCA 2A3 BLACK PLATE US

Product code: NOS2A0044

350,01

RCA 2A3  DUAL GETTER

GM uMhos : 5300-5040

 


RCA 2A3 BLACK P.

Product code: NOS2A0045

350,01

RCA 2A3  DUAL GETTER

GM uMhos : 5400-5500

 


RCA 2A3 "GRAY PLATE"

Product code: NOS2A0050

390,00

RCA 2A3 "GRAY PLATE" PAIR

GM 4950 uMohs 5050 uMohs

 


GEC GZ30

Product code: NOS300001

45,01

GZ30 5Z4 GEC

four pcs availables

 


WESTERN ELECTRIC 300B

Product code: NOS300B0001

1.950,00

WESTERN ELECTRIC 300B

SQUARE GETTER

 


GOLD AERO-WE 310A

Product code: NOS3100003

488,00 VAT included

310A WESTERN ELECTRIC

PAIR

 


MULLARD CV2821 ECC33

Product code: NOS330001

580,00

CV 2821 ECC33 MULLARD PAIR Mu 34.0-35.0  35.0-36.0

 


MULLARD ECC33

Product code: NOS330003

580,00

ECC33 MULLARD PAIR

Mu 34.0-35.0  35.0-36.0

 


MULLARD ECC33

Product code: NOS330004

580,00

ECC33 MULLARD PAIR

Mu 36.0-37.0  36.0-38.0

 


MULLARD ECC33

Product code: NOS330005

470,01

ECC33 MULLARD PAIR

Mu 33.0-36.0  35.0-37.0

 


MULLARD ECC33

Product code: NOS330010

250,00

ECC33 MULLARD

Mu 36.0-36.0

 


MULLARD ECC33

Product code: NOS330011

220,00

ECC33 MULLARD

Mu 31.9-32.3

 


MULLARD ECC33

Product code: NOS330012

150,00

ECC33 MULLARD

Mu 43.0 - 38.0

 


MULLARD ECC33

Product code: NOS330013

190,00

ECC33 MULLARD

Mu 30.6 - 32.9

 


MULLARD ECC33

Product code: NOS330014

210,00

ECC33 MULLARD

Mu 32.0 - 32.0

 


RCA 5U4G

Product code: NOS5U0007

129,00

RCA CBS 5U4G

BLACK PLATE

 


SYLVANIA 5U4GB

Product code: NOS5U0008

35,00

SYLVANIA 5U4GB

BLACK PLATE

 


RAYTHEON 5U4GB

Product code: NOS5U0009

25,00

RAYTHEON 5U4GB

BLACK PLATE

 


PHILIPS 5U4G

Product code: NOS5U0010

39,00

PHILIPS 5U4G

BLACK PLATE

 


MARCONI 5Z3

Product code: NOS5Z0001

289,99

MARCONI 5Z3

MADE IN ITALY

 


MARCONI 5Z3

Product code: NOS5Z0002

190,00

MARCONI 5Z3

MADE IN ITALY

 


MARCONI 5Z3

Product code: NOS5Z0003

120,00

MARCONI 5Z3

MADE IN ITALY

 


MARCONI 5Z3

Product code: NOS5Z0004

90,00

MARCONI 5Z3

MADE IN ITALY

 


Marconi DA60

Product code: NOS600001

1.900,00

MARCONI DA 60 

PAIR

 


SOVTEK 6C33C-B

Product code: NOS6C0002

35,00

SOVTEK 6C33C-B

PERFECT MATCHING

 


SYLVANIA 6SN7GTB

Product code: NOS6S0015

65,00

6SN7 GTB SYLVANIA PHILCO

BLACK T PLATE

 


RAYTHEON 6SN7GT

Product code: NOS6S0035

95,00

6SN7 GT RAYTHEON PAIR

Mu 19.9-19.3 / 19.0-19.0

 


WESTINGHOUSE 6SN7GT

Product code: NOS6S0038

60,00

6SN7GT WESTINGHOUSE - RCA

Four pcs availables

 


SYLVANIA 5692

Product code: NOS6S0042

65,00

5692 6SN7 SYLVANIA PAIR

Mu 19.0-18.0

 


RCA 6SN7GT

Product code: NOS6S0048

140,00

6SN7 GT RCA PAIR

M19.2-19.1 / 19.0-18.0

 


RCA 6SN7GT

Product code: NOS6S0050

190,00

6SN7 GT RCA PAIR

Mu 18.0-19.0 / 18.0-19.0

 


RCA 6SN7GT

Product code: NOS6S0051

180,00

6SN7 GT RCA PAIR

Mu 18.0-20.0 / 18.0-20.0

 


RCA 6SN7GT

Product code: NOS6S0052

160,00

6SN7 GT RCA PAIR

Mu 18.0-21.5 / 19.5-21.5

 


SYLVANIA 6SN7GTB

Product code: NOS6S0072

99,00

6SN7 GTB SYLVANIA PAIR

"CHROME TOP"

 


BRIMAR 6SN7 GT

Product code: NOS6S0075

150,00

BRIMAR 6SN7 GT Mu 19.9-20.5