Tube kits - Nagra

Tube kits

Nagra replacement tube kits
All tubes used in Nagra HiFi elements follow a stringent selection process. This also applies for the replacement tube kits. Original tube kits are the only way to guarantee the excellence of your equipment and we do not recommend using any alternative supplies.

General information concerning tube types, selection process and tube replacement can be found in the “General tube information” drop-down.

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Tubes 300B 2pce

Set of two 300B tubes

This matched pair of 300B tubes can be used on both the 300p and 300i amplifiers.

(More information under “General tube information”)

Part No. 7155362000

Tubes 845B 2pce

Set of two 845B tubes

These matched replacement 845 triodes must be changed as a pair on a single VPA tower.

(More information under “General tube information”)

Part No. 7055280000

Tube kit PL-L JAZZ

Tube kit for the Classic range

This tube replacement kit contains different tubes depending on the Nagra tube preamplifiers

(More information under “General tube information”)

Part No. according to model

Tube kit PL-L JAZZ

HD DAC tube kit

This is a military specification equivalent to the ECC 82 tube.

(More information under “General tube information”)

Part No. 7055761000

General tube information

Classic range

Nagra PL-P,  PL-L, VPS and JAZZ rely on ECC 81 and ECC 83 tubes to deliver striking performance.

Nagra uses different tube brands depending on the application. ECC 81 and 83 are Electro Harmonix Gold Pin. These premium tubes have a large plate, they provide a superior dissipation over the originals designs. The gold pins avoid any risk or corrosion and contact issues over time.

P/N 7055760000: Replacement kit of tubes for PL-P (full set)
P/N 7055762000: Replacement kit of line tubes for PL-P (no phono)
P/N 7055764000: Replacement kit of tubes for PL-L and Jazz
P/N 7055767000: Replacement kit of tubes for VPS

General tube selection process

Each and every tube installed by Nagra goes through a very complex selection process. It begins with a 48 hour burn-in, followed by individual measurements. The resulting selected tubes – less than 50%, are then rated to become either line stage tubes phono stage tubes. Depending on the batch, usually less than 1% become a phono stage tubes!

845 and 300B tube selection

Nagra has built special electronic devices to burn-in the 845 and the 300B tubes. They go through a 24 hour burn-in of  8 hours a day for 3 consecutive days. This eliminates any defective tubes or ones with major problems that will not survive this initial alignment stage.

Each tube is individually warmed-up and measured on a computerized bench-test. They must fit a specific performance window which is narrower than the general tube specifications. As a result less than 50% of the tubes are selected.

The tubes are then matched in pairs before being tested on a reference amplifier, giving an overall test period of 48 hours in total, prior to official Nagra certification.

Tube ageing, when to replace them?

The ECC 81 and ECC 83 minimum tube life is 5000 hours. Actually, most tubes operate consistently for more than 10 000 hours.

Thus, the useful life of the tubes is somewhat unpredictable. Rather than replacing the tubes arbitrarily after 5000 hours, we suggest that you identify the signs of ageing:

  • The distortion gently increases to an audible level;
  • Presence of clicks (dry and short noises, like that of breaking dead wood);
  • Presence of pops, short noises in the low frequencies;
  • Presence of hiss, higher background noise.

As soon as one of these signs appears, please contact your Nagra dealer to order a replacement tube kit corresponding to your equipment.

Can I use other tubes than the one supplied by Nagra

As a rule, we do not recommend using tubes from other sources. We often run tests with other tubes and we won’t recommend them due to various technical and reliability issues. Beware, that using tubes other than those supplied by Nagra will void the warranty of your unit.

For amplifiers, should I change one tube, a pair, a quad?

It is recommended to change tubes as a pair or preferably a quad as tube age will change the sound slightly so changing them by quad will ensure a consistent left / right performance.

However, in some situations of early failure, your Nagra dealer in contact with our Service Department, can provide a single replacement tube as close as possible to the one you want to change.

Different Nagra tube kits available

P/N 7055280000: Matched pair of 845 tubes
P/N 7155362000: Matched pair of 300B tubes
P/N 7055760000: Replacement kit of tubes for PL-P (full set)
P/N 7055761000: Replacement tube for HD DAC
P/N 7055762000: Replacement kit of line tubes for PL-P (no phono)
P/N 7055764000: Replacement kit of tubes for PL-L and Jazz
P/N 7055767000: Replacement kit of tubes for VPS

Tube warranty period

All tubes and tube kits supplied by Nagra have a limited warranty of 6 months.

Hear for yourself

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Tube kit PL-L JAZZ