Nagra Classic Preamp tube rolling

[Cleese74]

Hello, I am a happy owner of a Nagra Classic Preamp. Soon I will need to replace the tubes,
2x 12AX7 / ECC83
1x 12AT7 / ECC81
I don't know if buy the "official" Nagras or start the tube rolling.
Does anyone experimented with other no-Nagra tubes?

Thanks! Kind regards

 

[Holmz]

Hello, I am a happy owner of a Nagra Classic Preamp. Soon I will need to replace the tubes,
2x 12AX7 / ECC83
1x 12AT7 / ECC81
I don't know if buy the "official" Nagras or start the tube rolling.
Does anyone experimented with other no-Nagra tubes?

Thanks! Kind regards

I’m sort of piling on here.

I had a weak low powered channel today, and just got back from getting a couple of new cables.
Somehow the volume is equal again and the Mrs said to turn down the music.
So I suspect I pulled a wire loose on one of the XRL cables.

However the question remains…
The availability of the tubes in 12ax7 are:
- Sovtek
- Mullard
- Electro-Hamonix
- Svetlana
- Tugsol

Any recommendations or insights?

 

[CDawg]

Here's some measurements I've taken on a Maxipreamp II for current production or easily acquirable new 12AX7 tubes .The first two values are gain, the next two values transconductance and the final two values noise. Rounded and should have that negative for the dbv noise value. IIRC Electro Harmonix 1, 5, Tung Sol 1, 2, 4, 5 and Psvane 3, 4 are the gold pin versions and the other ones are the regular pin.

New Sensor Tubes

Electro Harmonix

1 90, 89 1820, 1750 83, 84
2 105, 94 1720, 1680 86, 86
3 91, 91 1730, 1780 84, 84
4 99, 99 1850, 1850 81, 83
5 93, 91 1870, 1780 83, 83
6 97, 96 1890, 1840 83, 84

Electro Harmonix 7025

1 83, 85 1600, 1580 86, 85
2 85, 84 1540, 1540 86, 85
3 85, 83 1570, 1530 86, 85
4 85, 83 1580, 1600 86, 85
5 82, 81 1600, 1580 85, 85

Gold Lion

1 97, 97 2190, 2190 82, 82
2 100, 100 2170, 2180 83, 82
3 95, 95 2300, 2280 83, 81
4 97, 96 2300, 2300 83, 82

Gold Lion CV 4004

1 96, 96 2040, 2050 82, 84
2 94, 94 2000, 1980 81, 82
3 93, 93 1810, 1820 80, 82
4 94, 93 1950, 1920 81, 80

Mullard

1 98, 96 2230, 2310 83, 81
2 98, 97 2020, 1960 82, 82
3- 100, 97 2040, 2300 83, 81
4 98, 98 2390, 2030 82, 82
5 98, 98 2260, 2220 83, 82
-
Mullard CV4004

1 94, 92 1870, 1720 84, 84
2 93, 95 1780, 1670 86, 84
3 95, 93 1650, 1850 86, 83
4 94, 94 1780, 1930 86, 84

Sovtek 7025

1 98, 95 1680, 1600 84, 70
2 94, 93 1710, 1630 81, 83
3 98, 99 1850, 1820 82, 84

SovtekWA

1 96, 95 1650, 1670 84, 83
2 91, 93 1700, 1700 84, 84

SovtekWB

1 110, 108 1860, 1810 84, 83
2 110, 106 1820, 1810 82, 83

SovtekWC

1 100, 101 1880, 1890 83, 82
2 102, 101 1900, 1870 83, 84

Sovtek LPS

1 96, 98 2240, 2170 79, 79
2 100, 99 1940, 2200 84, 82
3 95, 90 2140, 2070 83, 82
4 102, 98 1870, 1970 84, 83
5 96, 95 2240, 2220 85, 84
6 99, 97 2140, 2150 81, 82

Svetlana

1 90, 92 1860, 1880 85, 83
2 94, 94 1900, 1890 83, 83
3 92, 93 1820, 1830 85, 84
4 95, 96 1860, 1910 84, 83

Tung Sol

1 90, 93 2050, 2050 84, 82
2 89, 88 2020, 2050 84, 82
3 95, 94 1790, 1770 84, 85
4 87, 89 1900, 1990 82, 82
5 88, 89 1970, 1960 83, 82
6 92, 91 1670, 1780 84,83
7 96, 95 1840, 1840 82, 83



JJ

ECC83S

1 98, 100 1860, 1900 86, 84
2 101, 102 1990, 1940 87, 85
3 105, 99 1980, 1860 84, 83
4 103, 96 1970, 1890 82, 82
5 103, 101 1910, 1850 85, 84
6 104, 107 1920, 2020 84, 84
7 97, 96 1900, 1810 83, 83
8 106, 109 2090, 1880 84, 82

ECC803

1 96, 94 1730, 1780 84, 85
2 96, 100 1890, 1800 80, 83
3 97, 97 1740, 1840 84, 84
4 97, 96 1840, 1770 83, 83

E83CC

1 96, 94 1960, 1960 84, 84
2 94, 99 1950, 1880 83, 82
3 97, 98 1820, 1730 85, 85
4 100, 100 1820, 1770 86, 85
5 92, 102 1860, 1970 83, 82


Chinese Tubes

7025 Welded Plates/Genalex silver pin

1 110, 92 1850, 1970 81, 81
2 111, 104 1740, 1810 83, 82
3 108, 107 1740, 1780 83, 83
4 109, 109 1690, 1720 83, 83

Black Coating 12AX7T

1 81, 89 1880, 2080 81, 81
2 88, 93 1990, 1950 81, 81
3 83, 91 2080, 2110 83, 83
4 96, 94 2080, 2130 84, 82
5 89, 93 2190, 2050 82, 82
6 95, 92 2020, 2090 82, 81

Beijing Triple Mica 6N4-J 12AX7 C8

1 97, 96 1930, 1960 86, 85
2 93, 95 1920, 1810 84, 84
3 94, 90 1850, 1940 84, 84
4 95, 88 1980, 2000 83, 83
5 97, 92 1860, 1900 83, 83
6 96, 92 1960, 2020 84, 84
7 94, 96 1980, 1840 84, 84

Psvane

1 95, 68 1660, 1710 85, 79
2 82, 86 2120, 2000 82, 82
3 88, 87 2200, 2080 82, 82
4 84, 88 2010, 2140 83, 82
5 91, 88 2070, 1570 78, 83
6 93, 92 1950, 1990 78, 75

Shuguang 12AX7B

1 94, 94 2020, 2030 82, 82
2 95, 93 2040, 2030 83, 82
3 87, 88 2100, 1980 84, 82
4 97, 94 1920, 1910 84, 83
5 93, 94 1810, 1770 84, 83
6 94, 93 2030, 1980 83, 83
7 91, 89 1730, 1660 81, 82

Sovtek WB copy

1 101, 96 1630, 1580 82, 82
2 97, 91 1530, 1590 83, 83
3 104, 100 1480, 1560 85, 83
4 94, 96 1560, 1530 83, 83
5 97, 98 1440, 1560 86, 85
6 102, 101 1340, 1420 86, 85
7 99, 96 1610, 1480 85, 85

 

[Holmz]

Much appreciated @CDawg !

 

[oldvinyl]

Here's some measurements I've taken on a Maxipreamp II for current production or easily acquirable new 12AX7 tubes .The first two values are gain, the next two values transconductance and the final two values noise. Rounded and should have that negative for the dbv noise value. IIRC Electro Harmonix 1, 5, Tung Sol 1, 2, 4, 5 and Psvane 3, 4 are the gold pin versions and the other ones are the regular pin.

New Sensor Tubes

Electro Harmonix

1 90, 89 1820, 1750 83, 84
2 105, 94 1720, 1680 86, 86
3 91, 91 1730, 1780 84, 84
4 99, 99 1850, 1850 81, 83
5 93, 91 1870, 1780 83, 83
6 97, 96 1890, 1840 83, 84

Electro Harmonix 7025

1 83, 85 1600, 1580 86, 85
2 85, 84 1540, 1540 86, 85
3 85, 83 1570, 1530 86, 85
4 85, 83 1580, 1600 86, 85
5 82, 81 1600, 1580 85, 85

Gold Lion

1 97, 97 2190, 2190 82, 82
2 100, 100 2170, 2180 83, 82
3 95, 95 2300, 2280 83, 81
4 97, 96 2300, 2300 83, 82

Gold Lion CV 4004

1 96, 96 2040, 2050 82, 84
2 94, 94 2000, 1980 81, 82
3 93, 93 1810, 1820 80, 82
4 94, 93 1950, 1920 81, 80

Mullard

1 98, 96 2230, 2310 83, 81
2 98, 97 2020, 1960 82, 82
3- 100, 97 2040, 2300 83, 81
4 98, 98 2390, 2030 82, 82
5 98, 98 2260, 2220 83, 82
-
Mullard CV4004

1 94, 92 1870, 1720 84, 84
2 93, 95 1780, 1670 86, 84
3 95, 93 1650, 1850 86, 83
4 94, 94 1780, 1930 86, 84

Sovtek 7025

1 98, 95 1680, 1600 84, 70
2 94, 93 1710, 1630 81, 83
3 98, 99 1850, 1820 82, 84

SovtekWA

1 96, 95 1650, 1670 84, 83
2 91, 93 1700, 1700 84, 84

SovtekWB

1 110, 108 1860, 1810 84, 83
2 110, 106 1820, 1810 82, 83

SovtekWC

1 100, 101 1880, 1890 83, 82
2 102, 101 1900, 1870 83, 84

Sovtek LPS

1 96, 98 2240, 2170 79, 79
2 100, 99 1940, 2200 84, 82
3 95, 90 2140, 2070 83, 82
4 102, 98 1870, 1970 84, 83
5 96, 95 2240, 2220 85, 84
6 99, 97 2140, 2150 81, 82

Svetlana

1 90, 92 1860, 1880 85, 83
2 94, 94 1900, 1890 83, 83
3 92, 93 1820, 1830 85, 84
4 95, 96 1860, 1910 84, 83

Tung Sol

1 90, 93 2050, 2050 84, 82
2 89, 88 2020, 2050 84, 82
3 95, 94 1790, 1770 84, 85
4 87, 89 1900, 1990 82, 82
5 88, 89 1970, 1960 83, 82
6 92, 91 1670, 1780 84,83
7 96, 95 1840, 1840 82, 83



JJ

ECC83S

1 98, 100 1860, 1900 86, 84
2 101, 102 1990, 1940 87, 85
3 105, 99 1980, 1860 84, 83
4 103, 96 1970, 1890 82, 82
5 103, 101 1910, 1850 85, 84
6 104, 107 1920, 2020 84, 84
7 97, 96 1900, 1810 83, 83
8 106, 109 2090, 1880 84, 82

ECC803

1 96, 94 1730, 1780 84, 85
2 96, 100 1890, 1800 80, 83
3 97, 97 1740, 1840 84, 84
4 97, 96 1840, 1770 83, 83

E83CC

1 96, 94 1960, 1960 84, 84
2 94, 99 1950, 1880 83, 82
3 97, 98 1820, 1730 85, 85
4 100, 100 1820, 1770 86, 85
5 92, 102 1860, 1970 83, 82


Chinese Tubes

7025 Welded Plates/Genalex silver pin

1 110, 92 1850, 1970 81, 81
2 111, 104 1740, 1810 83, 82
3 108, 107 1740, 1780 83, 83
4 109, 109 1690, 1720 83, 83

Black Coating 12AX7T

1 81, 89 1880, 2080 81, 81
2 88, 93 1990, 1950 81, 81
3 83, 91 2080, 2110 83, 83
4 96, 94 2080, 2130 84, 82
5 89, 93 2190, 2050 82, 82
6 95, 92 2020, 2090 82, 81

Beijing Triple Mica 6N4-J 12AX7 C8

1 97, 96 1930, 1960 86, 85
2 93, 95 1920, 1810 84, 84
3 94, 90 1850, 1940 84, 84
4 95, 88 1980, 2000 83, 83
5 97, 92 1860, 1900 83, 83
6 96, 92 1960, 2020 84, 84
7 94, 96 1980, 1840 84, 84

Psvane

1 95, 68 1660, 1710 85, 79
2 82, 86 2120, 2000 82, 82
3 88, 87 2200, 2080 82, 82
4 84, 88 2010, 2140 83, 82
5 91, 88 2070, 1570 78, 83
6 93, 92 1950, 1990 78, 75

Shuguang 12AX7B

1 94, 94 2020, 2030 82, 82
2 95, 93 2040, 2030 83, 82
3 87, 88 2100, 1980 84, 82
4 97, 94 1920, 1910 84, 83
5 93, 94 1810, 1770 84, 83
6 94, 93 2030, 1980 83, 83
7 91, 89 1730, 1660 81, 82

Sovtek WB copy

1 101, 96 1630, 1580 82, 82
2 97, 91 1530, 1590 83, 83
3 104, 100 1480, 1560 85, 83
4 94, 96 1560, 1530 83, 83
5 97, 98 1440, 1560 86, 85
6 102, 101 1340, 1420 86, 85
7 99, 96 1610, 1480 85, 85

Interesting results. The Electro Harmonix 7025, Mullard CV4004 and Svetlana were consistent in measurements and low noise. I wouldn't choose the highest gain tubes, some of them have higher noise levels.

 

[CDawg]

Interesting results. The Electro Harmonix 7025, Mullard CV4004 and Svetlana were consistent in measurements and low noise. I wouldn't choose the highest gain tubes, some of them have higher noise levels.

It would obviously help to have more samples but I think people can look at that data and do a bit of statistical analysis and interpret it in their own way. Another option is to go on ebay and just type 12AX7 maxi for example and then you can get ideas without even buying them. You see 5 or 10 of those tubes over a period of months and then you have an idea what things should be. It's mostly inference but at least you're going in with something.

I'm picky so a Siemens E83CC is my favorite tube for a low noise 12AX7. Out of all the tubes I've tested I can honestly say that for a 12AX7 a EH 7025 had the lowest transconductance of any new tube and a Gold Lion by average and a Mullard by extreme had the highest transconductance I've measured. Whether NOS or current production. Same company has the extremes of values in transconductance for a ECC83. Always thought that was interesting.