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Email reply from Eurotubes about JJ KT-77 quality issues

4.245.65.31

Posted by Vatron on April 25, 2006 at 11:56:36

In Reply to: Testing & Examination Results - Not Good News! posted by Jim McShane on April 24, 2006 at 13:03:35:

Hello everyone,

After reading Jim McShane's findings of poor quality with his batch of JJ KT-77's.
I felt compelled to contact Eurotubes to inquire about the quality issues at hand.

After all of the positive comments about this new vacuum tube.
I would hate to see the future success of this or any other vacuum tube be put in jeopardy.

I hope that anyone who has issues with this or any other new production vacuum tube, will make their problems known to the manufacurer.
In hopes that your voice will make a difference in these issues, by letting the manufacturer know of poor quality and dissatisfaction by voting with your feet.

PS. I have no affilliation with Eurotubes or interest in this issue at all, except helping tube heads keep a good supply of quality new production vacuum tubes flowing.

Sincerely,

Norris Wilson

Reply by Eurotubes:

Hi Norris:

I tried to follow the link but all I could ever get was the first page with Jim’s rant on it so I will address the issues he brought up.

I am not in the business of just selling tubes to sell tubes so I am always 100% honest about everything. Just as with any tube produced today, all tubes are simply batch tested at about one piece per one hundred. The glory days of having all tubes tested 100% when factories could afford to have extensive QC departments are gone.

That said, it’s now up to the re-seller to do this. We go thru all tubes 100% and anything that is not performing at 100% gets tossed. We will also hold out tubes that are severely tilted in the bases (I use them in my own gear) it of course does not hurt the performance.

There will be mica particles in quite a few tubes but these things are not new and I have plenty of NIB NOS RCA, Sylvania and a host of other brands that are very crooked in the base and look like snow globes because of all the mica flakes in them. Once again these things do not hurt the performance and it’s noting new.

Now the most important fact. We track all tube failures and the overall average is just under .5%. That is a little less than one half of one percent. As you may or may not know JJ built the KT77 at my request and as part of our business arrangement I was the only re-seller to have them up until a couple weeks ago so I’m the only one with a track record.

I received the first test batch of the KT77’s the first week of December 2005. In January after speaking with JJ about the tube I received the second pre-production batch. They were trying to get the TC up a little more and I warned that they needed to keep the plate current draw down where it was or these would not be a drop in for EL34’s. Well you guessed it. The plate current draw doubled… Not good for a lot of amps with limited bias adjustments or fixed bias amp where the owner does not want to change out the bias resister.

A few weeks later the first real production batch came in and the TC was still up and the plate current draw was back down to EL34 levels! The failure rate was and is still the same.

So to date out of several thousand KT77’s we have had six failures which is less than one half of one percent. I have had one customer with a Dynaco 80 that called these the worst tubes he has ever heard. The general consensus is that they are a great tube. My personal opinion is that they are doing a great job in several of my amps and have not let me down.

Tube rattle in combo amps has been plaguing mankind ever since the decision was made to place tubes inside of a speaker cabinet when the first combo amp was born. Tube rattle is a MAJOR problem with all brands of tubes and I have been working on this problem with Jamona ( the owner of JJ Electronic ) and we have come up with a double mica JJ 6L6GC that JJ is making just for me for use in combo amps and these have reduced rattle complaints by about 75% I have not even advertised about these yet because I have been collecting field data over the past 10 months. I have recently asked Jamona if he will conceder making all the tubes I get this way. No answer yet.

The last thing to address is the pin size. JJ was getting hounded by lots of amp manufacturers to down size their pins because they were tight in a lot of higher end sockets. Without notice they changed the pin size decreasing it to .089 from .094 Five thousandths does not sound like much but it has satisfied the few and angered the masses…

In January I had a face to face with Jamona and explained the situation as being an astronomical pain in the ass so he agreed to up the size to .094 again and starting in May this will be the standard. Until then I will spend a good portion of my day explaining how to retension tube sockets…

So there you have it. If I have left anything open here or not answered your questions with enough detail I would be happy to extrapolate. You also have my permission to quote any or all of this email.

Thanks

Bob

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