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Burned Out

I recently got caught up in the tube swapping craze. I have a tubed amp and preamp. I researched things as well as I could for only having access to the internet and forums like this. I also was in contact with the owner of a very well known vintage tube dealer. I bought two tubes from eBay from dealers with a long history on eBay and high customer review rating. Both tubes from eBay were for my preamp, one  was a Brimar and the other Melz 1578 6sn7 tubes manufactured in the 50’s or 60’s. The Brimar only played through one channel and at first dealer tried dispute the fact that it malfunctioned and then contacted me saying he was now having the same issue. The Melz red plated on me and was very microphonic. The dealer is in the Ukraine so I’m waiting to see if I will get my refund. And, last but not least one of the most reputable dealers recommended a tube RCA and has stated he stands behind his product. But, what happens when his product causes damage to your preamp? My preamp now plays only through one channel. When I called up the dealer about the noise the tube was making, I was told follow the instructions regarding microphonics and that there was no way the tube would damage my equipment. There was a recommended break in period of around 48 hrs. Well long story short, my preamp is not functioning and has to be sent back to manufacturer and as of on out $115 for the tube. So my question is are NOS tubes worth all the risk? Are the newer tubes that bad that I have to sacrifice the working condition of my gear for a possible sound improvement? I would like to know your thoughts. Are tubes the Shuguang Black treasure, Northern Electric, a safer risk. I’m venting right now, but looking for answers
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sidog1460 OP
59 posts
 
I’m not going to complain and put down someone’s business, but the dealer was one of the first rate sellers. I contacted him when I thought there was an issue(I’m somewhat new to tube rolling). I followed his instructions and kinda let my guards down thinking I was being too cautious and he had to be right. I learned the hard way, no one cares about your gear as much as you, and no one knows everything about every single amp or preamp and how it will respond to something new in your system. Sure he’ll probably replace the tube, but I’m stuck with the repairs and shipping.

speakermaster
738 posts
 
Do not buy tubes on ebay or without making sure your gear is voltage compatible with NOS tubes many times the voltages are wrong in the old tubes for modern tube gear I would suggest trying andy's tubes. I have bought some of his graded tubes and they are absolutely wonderful and trouble free.
inefficient
40 posts
 
I would buy from Ukraine only what was made in Ukraine, or made in USSR. Looking at the list of Soviet valve factories, I see some 30-40 names, 7 in Ukraine. No idea which tubes they made. What was not made in Ukraine, was made in Russia, or on rare occasions elsewhere, and could be in Ukrainian stockpiles, esp. military valves like 6С33С, etc.
But I noticed that none of the Soviet factories had name “Brimar”.
— Why on earth a dealer in Ukraine (or Russia, or Poland, or my native Latvia) would have a sizeable stock of NOS valves made in Western Europe, or in the States, available at so competitive prices they can re-export them?
Wherefrom?? They were not close to the sources, they did not have spare money to buy up surplus stock.
Given that - what are the chances of counterfeiting? Rebranding local NOS stock, re-branding new local or Chinese or Russian production... I for one most probably could not tell the difference.
lexx21
75 posts
 
I’m sorry to hear about your burnout, but the sellers didn’t test the tubes before they sent them to you. My guess is that they have a large enough volume going out that they can afford a few pissed off customers.

I had a "nos" 12ax7 rca blak plate literally implode on me in my conrad johnson mc55. That was a real b---- to get out. Lesson learned.
There is nothing wrong with NOS tubes as long as they are tested beforehand. If they test good, then they will likely run ok. I don’t mean testing on a mutual conductance tester, those are crap and you would find those in drug stores in days past. I’m talking real Mu testers that test at actual operating voltages.

If you can find a seller that does that, then you are pretty much guaranteed to get a good tube. If not, then you will be playing Russian roulette. I had a very good looking st 6v6 blow the fuse right off the bat on me because it was shorted. Unless the glass is broken and the getter has gone grey, you can’t tell that a tube is bad or not. Hence the testing....
bigkidz
3,387 posts
 
Tubes will be tubes - even new production tubes can have an issue.

First learn what makes the sound - sound the way it does.

Miller - diodes eh, resistors yes capacitors yes - transformers chokes yes but it comes down to the design  DHT, point-to-point wiring, AC filter chokes, capacitors and resistors all have an impact.

Best advice - learn to solder!

I built a preamp with a rotary switch where you can simply change out the resistors on the fly.  Now that was fun to show people the differences especially all those who told me that they would not be able to hear the differences..

I have also built cost no object components and just recently build a few to various price points.  Some of these are getting very close to the cost no object builds because we have figured out what parts make the best sound - at least to our ears!

Happy Listening.
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