GOOD TUBES, BAD TUBES

Hi, sorry to read about your tube experiences. About five years ago, I re-tubed a McIntosh  MR-71 FM tuner with replacement tubes that were all NOS. It was expensive, but worth it. I used Telefunken tubes from the 1950's and 1960's, all bought from reputable online tube dealers. I deliberately avoided using new tubes because of issues raised by axpert's post. The results of my project? The tuner sounds wonderful, glad I spent the money to do it. 

I have bought quite a few tubes lately.  No problems with small input tubes, these guys last forever.  Got a couple of bad power tubes.  Some were NOS and some were tested good.  I got one bad tube of each kind.  These were ebay purchases.  I politely contacted the sellers who promptly sent me a good replacement. One was from Slovenia. No stress.  --Jerry

"I re-tubed a McIntosh  MR-71 FM tuner with replacement tubes that were all NOS. It was expensive, but worth it. I used Telefunken tubes from the 1950's and 1960's, all bought from reputable online tube dealers."

Scorpio1951-

I use a 65 MR 71. 13 NOS Telefunken  tubes= WOW, kinda pricey? I was advised  just the 2(L/R)audio output tubes would (if at all) make a noticeable SQ difference and a alignment with any tube change regardless of tube pedigree and proper antennae make biggest impact.

I use a pair of Raytheon's in the output stage. The rest are RAM "premium" grade(also pricey, but not as bad as your Tele's)

Sounds like the first three gentlemen that responded were smarter than I, or at least "should have been". I recommend that if anyone asks for a source recommendation for vacuum tubes, that you steer them away from CHINA-HI-FI

Thanks gentlemen for you input.

Thanks. I have looked at that page, & considered buying a quad of Psvanes or Shuguang KT88T. However their shipping charge was quite ridiculous, IE $100+ to the US. I tried email to check if that was correct but never got a reply. That told me a lot about customer service. Actually, Customer service in that area of the world seems to have a different meaning than what I am accustomed to.

In my experience customer service from China has been invariably good - very polite, and prompt.

Issues with tubes present some issues and I’d be a bit circumspect too if I was a vendor, knowing the tricks some people get up to. Having said that, they do provide this assurance on their web site -

> All of our products will have an ONE YEAR Full Warranty (including labor and parts), and an ONE YEAR Warranty on the vacuum tubes.

> The warranty on the tubes covers parts only as they are easily exchangeable by the final user.

A tip with tubes (as with many things) - steer well clear of trying to get the cheapest price.

Known as false economy. Its not a new concept - what is the reason people don’t know this?

Further to the false economy concept, there is the saying "I’m not rich enough to buy cheap things".

This may appear to be a paradox. Think.

                                     JUNK?   From CHINA?

to maximise tube life always check your filament voltages and get them to run just under spec. Amazing how many amps have filaments running hot, especially the 110/220V Chinese jobs. Use padding resistors to lower voltages and extend your listening time..

"UPSCALE, in my opinion is the most reliable source anywhere."

Well...

OK, then.

DeKay

I just got burnt by a well known and respected US tube dealer.   They sent 6 NOS rectifiers, all but one looked like "pulls" , they were definitely used.   One had no Getter left, it was gone.  The pins had patina where they had prolonged contact with a socket.... needless to say I am pissed.  They just said, " sorry for your tube troubles,  all of our tubes have a 90 day warranty "   That pissed me off even more , its not "my problem " at all because I didn't commit fraud....they did..  I am disputing the sale with PayPal.   Once I take pics of the crap they sent I will be sure to share them.   

@oddiofyl -

     Patina is a result of a material's exposure to things in the atmosphere, not to those found in a tube socket.

                              https://en.wikipedia.org/wiki/Patina

     I've never seen tube pins corrode, due to contact with a dissimilar metal, because: manufacturers have been aware of that problem, for many decades.    The presence of an electrolyte is typically required, for that to occur, anyway.

                                     Pin pics would be of interest!

     An interesting allegation, though: I suppose anything's possible, now days!

  "The pins had patina where they had prolonged contact with a socket...."

Believe me,   I know a tube has been in a socket a long time when there is discoloration only where the sockets contact the pin.  2mm i shiny, 6mm is brass looking and the last 2mm is shiny.  It was in a socket.  Without question.  

Dust was baked to the micanol and glass....  some of the bases were heat dimpled.....  I am not new to tubes.

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

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

@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