2. tech-talk
  3. 175866-138745

GOOD TUBES, BAD TUBES

Have you ever purchased (1) one or more "NEW" ( not NOS ) replacement vacuum tubes;  - - especially POWER TUBES ? How satisfied were you of the results and especially, the seller ? Something I thought it important to share; - - - - I too have bought many tubes from dealers in the USA; - - especially UPSCALE AUDIO. =Though I've read that an occasional buyer was less than thrilled for one reason or another, UPSCALE, in my opinion is the most reliable source anywhere. The reasons why can be easily determined by visiting their website, and read what KEVIN has to say. Be it said, that this is merely a preface, and not a advertisement for UPSCALE.

In writing this, what my purpose is, to put forth a WARNUNG ! 

Recently I was looking for a "NEW" matched quad of KT88's at a good price. In doing so I became lured to CHINA websites. In particular,

"CHINA-HI-FI.COM" Seemingly a well established seller of many brands of CHINESE made audio gear including vacuum tubes. In scanning through their offerings I came across a listing of a matched quad of SHU-GUANG "TREASURE" KT88-Z tubes. A brand I have used in the past, successfully. The price was right so I went ahead with the purchase.  

Just recently, I had occasion to test the tubes, prior to installation. "OH MY GOD". I couldn't believe what I was seeing, and decided to go to a good tech in Chicago to verify.  I wasn't wrong !! All four tubes were defective in various ways. Gassy, extremely low output, shorts, etc. In other words they were all reject "junk". So, I contacted the seller in China, and notified him of my findings. It took a while for a response. He wanted pictures. Then the usual rhetoric !! I asked him for an immediate refund, "NOT REPLACEMENTS". As I should have expected, he went silent on me.  Frankly, I am of the opinion that he knew he was selling me defective tubes. Otherwise, you would think that at least one of the four would have tested good.

So at this point all I can do for my fellow audiophiles is send out a warning about CHINA-HI-FI.COM. If this is an example of how they do business,- - - 

well, you get the idea.

128x128axpert
larsman's avatar
larsman
2,071 posts
 

Good tubes, bad tubes, you know I've had my share.... 

sns
3,439 posts
 

In regard to new Chinese power tubes. I've purchased from both North American and Chinese sellers over the years. A number of things to be aware of. First, Chinese sellers are selling from common Chinese stocks, these tubes may or may not be reliable, quality control seriously lacking for their domestic market. If you buy from North American seller who purchases relatively large stocks of Chinese tubes, those sellers can't afford to sell from stock of high failure rate tubes. Therefore, these sellers will demand the best quality tubes from the factory in order to retain their good name, and the factory will be motivated to sell them best quality stock to retain their market position in NA market.

 

On the other hand,  you may be lucky in purchasing tubes from Chinese sellers, assuming reviews and posts on forums are authentic some are happy with their purchases. The other thing to keep in mind is replacement in case of failure, big hassle sending back to China. I know this from personal experience, I had one tube fail in two separate purchases from Chinese dealers, one DIA and the other within 20 hours. I had to send proof of failure in the form of video showing serial number and audio recording popping of tubes, then return that tube to China for replacement. Add up shipping, hassle of documenting failure, wait time for replacement, especially with today's shipping issues, I will never again purchase from Chinese sellers. This is not say they're thieves or scammers, its simply the nature of the business. The premium price we pay for purchasing from NA sellers vs Chinese sellers is worth it for me. I've had good experiences with Grant Fidelity and Woo Audio for Chinese power tubes. The Chinese power tubes can be extremely nice sounding tubes, buy from reputable seller and you'll check the box on reliability and simplified replacement in case of failure.

 

I'll also remind people Chinese tubes are not the only tubes with reliability issues these days. As always, one needs due diligence in the purchase of new power tubes, or any tubes for that matter. Part of that due diligence  is knowing maximum plate voltage, current and dissipation of amp or pre tube is going in. Lacking that, a successful track record of a particular tube in a particular amp is helpful. In perusing many forums over many years in regard to tube failures, it often turns out some of these tube amp manufacturers run these tubes hot, tubes are not always at fault.

 

I

rodman99999
6,200 posts
 

@oddiofyl -

     Ah, so: the pins have the typical scratch/polish, from working against a socket’s fingers/walls, not, "patina".

        It’s hard not to get those from plugging tubes into certain testers, as well, but: hey...

                                              No pin pics necessary.

                                                    Happy listening

More to discover