Buying Tubes / Avoiding Duds

D

deltaunit

New member
I was just wondering if there was some good advice for buying good quality no noise tubes whilst avoiding the duds, especially avoiding those noisy/hissy tubes?

What tests and what results are worth looking out for, if any? What does a gas/emission test result indicate? Ma figures? New old stock? % Section??

Out of the 4 input tubes I've purchased I had 2 bad ones, so any advice would be gratefully received, especially how it relates to noise!

Tx
 
Thanks again Grainger; they say quality pays and if buying from a trusted source helps avoid getting stuck with a dud then the benefit is clear, especially to me having just waisted $40!

Do all NOS tubes tend to be quiet? And are the enhanced ratings these companies offer more about L/R level and pair matching?
 
Another way to approach the issue is to reduce the cost of the tube(s) that you purchase.

First I have found that whenever I meet people I don't know, I mention that I like to build tube amplifiers. Occasionally somebody mentions that they either have a box of the things that their father had or whatever. Usually they are glad to get rid of it and usually the box contains some well known tubes that you already know of such as 12AU7, 6SN7, 6V6 or whatever. Usually there are a bunch you have never heard of, but as you get more into the hobby, you find other people have used them successfully. An example would be a 5687 or even a 12HG7. Of course you can't just substitute them because of their different electrical requirements but half the fun is working out how to use them.

Second, there has been the influx of Russian tubes that you buy off Ebay which are very well made and relatively inexpensive. Examples would be the 6N6P or GM70. You should also check out the teflon, PIO and silver mica caps which are wonderful value.

I sometimes think this hobby is much the same as the wine drinking hobby. There are so many great wines beyond chardonnay or cabernet sauvignon. You just have to try them.

I realize this doesn't really answer your question, but I hope you think about it.

ray
 
I general the gas/emission test will not tell you much except that the tube may be functioning and may give some indiication o how much life is left.  To my mind, it is a quick and dirty pass/fail test and no more, and even a tube that passes those tests can be horribly unbalanced, nooisy, microphonic, or whatever.  I never buy tubes that only have gas/emission tests.

In general though, buying from a reputable dealer should take most of the hasle out of it.

Other than that, I don't find any correlation between NO
S and noise or any other factor for that matter, and in plenty f cases they just don't sound as good as some (I stress *some*) goud sound.

In my el84 amp I'm running a new production driver, outputs and rectifier and they are easily outclassing most of the NNos tubes I've had in it, and some pretty rare, exotics at that.

Hope this helps,

Jim
 
Delta...

When I posted I was forgetting you are in England, all three I linked are in the US.  And since you are about an hour from London, American guess here, and there are a number of Bottleheads there, they like Scotch, we will see if we can make some connections.  Poster Paully here has at least one favorite seller in England and I sent him an email asking him to post in this thread.

I can't believe I didn't think of the Russian Military Surplus tubes before RayP did.  Not that Ray is slow, it is just that I am a big fan of these rugged and fine sounding tubes.  I just don't know if there are equivalents for Crack.  I do have several eBay sellers I have bought from if there are surplus equivalents for Crack.

NOS tubes have been around for a long time and might have been knocked around too.  That causes noise, so a premium NOS tube should be listened to in a circuit to asses the noise.  For example I have bought some tubes for my Seduction that were unusable, and received a refund because the seller was a good one.  I don't know what the ratings from tube testers mean, I wish I did.
 
Thanks the advice everyone and that's really kind of you Grainger, cheers.

I don't mind ordering from the US if I can find exactly right tube, and if those dealers test for quietness then the extra cost and inconvenience will be well worth it. I'm after a very specific valve now so I expect a bit of a prolonged hunt now to track a good one down...

My most recent tube was bought as being "tested at 100%" but as Jrebman says, this doesn't seem to be indicative of quality. At least I learnt a lesson there. I suspect that in any other application than a headphone amp a very slightly raised noise floor isn't such a major problem - my Naim SS amps hiss quite loudly if you're close up to the speaker.


 
I have a good friend who proudly pronounces himself a Luddite when it comes to high tech audio electronics. This person has one of the finest reputations in the audio business, and although we don't agree on some aspects of audio we do agree that his Luddite approach to testing tubes is the best. That approach being there is only one test that will assure that a tube will be quiet in the device you plan to use it in. You have to test it in that device. A fancy high tech tube tester will not create the same operating conditions and thus it can't tell you how the tube will work in your specific application with respect to noise. That is why reputable dealers will allow returns. Just make sure you get that assurance before to you order.
 
I have given up on "NOS" tubes.  I buy used old stock tubes sold by "Byrd", whose contact details you can get on Audio Asylum Classifieds under tubes for sale.  He tests all his tubes carefully; tells the truth; has reasonable prices; and will replace bad tubes.  I have never received a bad tube from him and I expect the quality is better than almost all tubes sold these days as NOS/NIB, but that's just a guess.

 
Lots more good advice, thanks everyone.

I've used Langrex successfully, I bought a Mullard 6080 from them - perfect! :)

Thanks Doc, that is the only way to be sure - I might try buying closer to home if I can get a similar deal on the tube I want.

If only every tube seller was so honest or thorough. I'm sure some on ebay are just selling bad tubes on in full knowledge. :(
 
deltaunit said:
I'm sure some on ebay are just selling bad tubes on in full knowledge. :(
Click to expand...

You have me chuckling. You can replace the word "tubes" in that sentence with just about anything old and collectible - watches, LPs, transformers, camera lenses, you name it.
 
Funny thing is I have had pretty good luck buying tubes on ebay.  My fair share of misrepresented crap, to be sure.  But taking the material I feel is indeed NOS versus what I would have paid retail from a reputable dealer less what I got screwed on, I am still ahead.  Of course most of this was bought many years ago.  Seems like I have had more questionable tubes in the last two or three years and have become more cautious lately.
 
Paully said:
  Of course most of this was bought many years ago. 
Click to expand...

Shoot, many years ago (pre the Web) people used to drive to my house with truckloads of tubes and just give them to me, and I filled my truck with tubes from more than one old timer's estate just to help the family clear the mess up. Ebay has changed the "hobby economy" permanently.
 
Dan at one time had an entire garage and a storage unit of tubes if I remember right.  There were a lot of them around, that is for sure.  I think that Bottlehead corp has happily reduced the hoard to a manageable size. ;-).
Richard
 
Oh, I don't think I ever had more than 10 or 15 thousand. These days I have one nice manageable pile of banker's boxes full of the stuff I skimmed. But it's slowly dwindling over the years as we have used tube in various projects.
 
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