I purchased a pair of Linlai tubes (from Grant Fidelity). I had my preamp serviced recently and discovered the tubes test low. The technician stated they tested lower than any other 12 or 6SN7 that he’s tested. And this was coming from a tube audio manufacture that utilizes a David Berning design. The tester reached out to Grant Fidelity to determine why this was the case given the tubes were purchased in Sept. 2022 and it’s October 2023 (13 months). He didn’t receive feedback to date. Caveat Emptor. I contacted the company and this is the received response: For within warranty period, please read below for our position of 3rd party measurement. Tube factory maintains its own product quality control and credibility to its own measurement procedure.
https://linlaiglobal.com/index.php/warranty/
Product test measurements: We do NOT accept any customer or 3rd party’s test measurement, on any brands of test equipment as the basis of warranty claim. If you do not agree with our test methods or test measurements, please do NOT place an order with us. By placing an order on our website, you have expressed explicit agreement to our product test methods and test measurements. This term cannot be re-negotiated AFTER an order is placed.
Regards,
[Linlai™ Global]