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Question about vacuum tubes test resuls and impact on sound
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Author:  Yoshimitsu [ 07 Feb 2020, 18:51 ]
Post subject:  Question about vacuum tubes test resuls and impact on sound

Hi!

I am new to this forum but i am very passionate about audio, especially vacuum tube amplifiers. I own a Decware Taboo MKIII tube headphone amp, connected to a Khadas Tone Board DAC, a USB isolator and to my PC. As headphone i am using the Fostex TH-X00. Currently installed vacuum tubes are rectifier: Svetlana 54ug black plate '50 signal tubes: 2x Hungarian Tungsram EL84 and as input: Siemens silver plate '60 E88CC.

Anyway, when looking for tubes, especially in ebay often in the describtion they put test results of the tube. I just bought 2x Philips SQ E88CC Herleen factory the sellere shared these test results: Tested on ELPO P-508 - Pair = 11/10 + 11/11 mA!

I asked the seller what the measurements mean and his answer was "hese are the currents after measurements, the maximum cathological values ​​are 14 mA, the lamps are not NOS but in a nice condition".

I am wondering do these values have any impact on the sound? I asked the seller and he responded "There is no difference for these tubes ..., e.g. the Soviet equivalent of 6n23p sounds great even at 4-5mA :)"

But i'd like to fact check that.

Can anyone confirm this?

And how do these values concern me as a buyer?

Also i'd like to know how to the Philips compare to the siemens?

My best regards and thanks a lot

Yoshi

Author:  ILoveHiFi [ 18 Feb 2020, 03:03 ]
Post subject:  Re: Question about vacuum tubes test resuls and impact on so

Unless the circuit requjres a matched valve, otherwise most circuits don't require matched valves.

A non matched and weak valve with high quality hifi construction will sound better than a non hifi valve perferctly matched.

Also majority of the time you recive the valve and the actuall matching of the valve differs from what buyer specified so is not recomended to chase highly matched valves.
Regardless of the supplyer.

Author:  Yoshimitsu [ 27 Feb 2020, 14:39 ]
Post subject:  Re: Question about vacuum tubes test resuls and impact on so

Hi

It isn't quite what i meant, i only have one 6922 slot.

What i meant is, when you look for tubes on ebay they mostly post measurements of emission tests for instance 16 mA/19 mA which corresponds to 106.6%/126.6% (100% is 15 mA) for Siemens E88CC tubes.

Let's that there is a second tube same everything as the first one that tests 23/22mA (153.3%/146.6%).

Would there be any sonic difference?

Author:  ILoveHiFi [ 03 Mar 2020, 22:23 ]
Post subject:  Re: Question about vacuum tubes test resuls and impact on so

You'd undlikley notice much diffrence, there will be a diffrence, but small.

Both channel will sound very similar unless the tubes are off by a very far ammount.
20% you will not notice any diffrence.

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