from customer Lyle C. by email:
“Greetings,
I bought a quad of the Shuguang Black Treasure 6CA7’s from you recently and love them. They are exceptional tubes, absolutely killing the EH 6CA7 and Tung Sol reissue EL34’s I’ve tried.”
This product has been discontinued permanently:
This product has been discontinued permanently:
This product has been discontinued permanently:
This product has been discontinued permanently:
I received a pair of your new copper foil caps (.22uF) yesterday and immediately installed them in my Yamamoto 45 amp as a coupling cap between the driver and power tubes. They are already remarkable after a few hours burn-in. I wouldn’t have believed how much they improve this wonderful amp. –William W
In the past, most Chinese tubes (including high end tubes) are sold over internet without adequate distribution quality control. Some consumers are confused about the quality grade on the Shuguang Treasure tubes and wonder if all Premium tubes out of factory are the same, and if the factory test readings are accurate.
Below is the sample testing results for Shuguang Treasure tubes that Grant Fidelity receive from factory in 6 months of time (Jan 2009-July 2009). They are self explanatory as you can read all the testing results obtained by Grant Fidelity’s 5-spec test. 1) Listing results are listed in the order of factory matched pair or quad (shaded or unshaded in the spreadsheets). If a tube is listed as single or a quad is not complete, it means the other one(s) have failed in our first test and graded as ‘Rejects”. 2) “Rejects” are not included in the list as those tubes are reported with ‘Short’ in the tester, hence no further results can be reported. 3) KT66-Z and 2A3-Z tubes are not as popular as other models, so they are not included as we don’t have sufficient data to deem the testing results as representative.
Shuguang Treasure 300B-Z:
Test results: https://docs.google.com/fileview?id=0B06Slh1HJxoKZDI5ZTMzNjktMWRmYS00NDQ2LTkxMDMtNWI0YTFjODg3Zjhm&hl=en
Shuguang Treasure CV181-Z (6SN7):
Test Results: https://docs.google.com/fileview?id=0B06Slh1HJxoKM2JkMWYwOWYtYTA5ZS00NzY1LTk2YzAtZGY5YjFjZGIxMjQz&hl=en
Shuguang Treasure KT88-Z:
Test results: https://docs.google.com/fileview?id=0B06Slh1HJxoKYTVmYTZiN2QtMDJhNS00ZmU4LTk1NzEtMGQzZTA2ZTlkMjky&hl=en
Shuguang Treasure 6CA7-Z:
Test results: https://docs.google.com/fileview?id=0B06Slh1HJxoKMDYwNzU4ZmMtYTcyMS00Y2EyLTk3NmUtZTRjMTAxOTVmYjJj&hl=en
The answer is – it depends on the test results.
A weak (low) emission tube will last shorter time than a strong one. But you may not hear the difference when both tubes are within operating range. When a tube emission gets too low, the tube as part of the circuit is no longer operating at the optimal condition and will cause distortion in sound. It may also stress other parts of your amp causing equipment failure.
Noise / micro phonics issue on a preamplifier tube can be heard. Micro phonic is common on large power tubes but it is not important for sound quality.
Heater-to-Cathode leakage cannot be heard, but it will kill the tube faster before you know it.
Excessive gas will certainly shorten the tube life – but you cannot hear it.
A set of tubes with bad matching may cause distortion in some cases and become audible.
Do you need perfectly tested and matched tubes? Not always. You have to find the balance point yourself. Not everyone is perfectionist, but a seller should make all information known to let the buyer to make informative decision.
This product has been discontinued permanently:
We provide Grant Fidelity Grade A matched pair or quad of tubes – these tubes are usually packed in one box with one test card showing the ‘plate current’ reading in ‘mA’
Some customers inquire why we are not providing 2 or 4 cards showing same readings on all tubes – the reason is: we match tubes in pairs or quads to our specification. No two tubes will have 100% identical reading so we provide the average readings of all matched tubes in the package. It is misleading and untruthful to provide you 2 or 4 cards showing all same readings on all tubes because they simply DO NOT have 100% the same readings.