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Amperex 6922 PQ's really cost this much? - Page 3

post #31 of 43
4/8/07 at 12:50am
Quote:
Originally Posted by J-Pak View Post
I don't think anyone has tried it in the Melos (according to the Melos tube rolling thread) so I'll hold off in case something blows up.
I'd definately get a second opinion before trying. The only thing that I am going on is Kevin Gilmore telling me that the 6BZ7 is basically a high gain 6922 when I asked him about it.
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post #32 of 43
8/30/07 at 1:05pm
Quote:
Originally Posted by gundam91 View Post
Just a general warning to everyone buying tubes on eBay! Make sure you do your homework. Know what you are buying, make sure the seller is reliable, and the tubes have been measured.

There are a lot of fake, relabeled tubes on eBay. Sellers might have tested a tube, but not checking to see if a tube has "short" or is "gassy", or "noisy".
How is one to know if the seller is reliable? Does anyone have any knowledge themselves of those who are reliable on ebay? or point to other sources?
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post #33 of 43
8/31/07 at 1:57pm
Quote:
Originally Posted by slwiser View Post
How is one to know if the seller is reliable? Does anyone have any knowledge themselves of those who are reliable on ebay? or point to other sources?
I followed these rules to the letter when I was very actively buying tubes on eBay about 6 or 7 years ago:

1/ The ad must have good quality picture(s) that clearly shows all the details. I have to be able to check all the characteristics listed on my checklist (to ensure the authenticity of the tubes);
2/ the seller has to have good reputation (feedbacks in the hundreds at least);
3/ test results provided. (If the seller is fairly reputable, I might buy the "untested" ones)

Bottom line, you are taking a risk on eBay, unless you know exactly what you are doing, and have a tester yourself, you are better off buying them from reputable dealers. There's a sticky thread on top that identifies who some of them are. Another good source is to go over to Audio Asylum (www.audioasylum.com) and check on the home page for a list of sponsors.

Few more recommendations before you venture to eBay. Do some background research, learn how to identify the tubes (that you are interested) from different manufacturers. Learn how to spot a fake. And as always, if the deal is too good to be true, it probably is. There are some fairly regular tube sellers on eBay back then, after a while, I ended up buying most of my stuff from just a selected few sellers.

Hope this helps.
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post #34 of 43
8/31/07 at 2:34pm
The 6BZ7 preceded the 6DJ8 and works great. In many applications I like it as much and in some more than the 6DJ8.

The tubes that sold look to be used. I have tested many gold pin tubes and the pins do not really discolor when testing but they do when they have been used for any length of time.

I like the 27 mesh plate very much. The Sylvania 1929 to 1932 mesh plate (nos) (the only way they were made then) is better than anything else on the market even all the varieties of that blue tube (nos). :^)
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post #35 of 43
8/31/07 at 2:47pm
gundam91 speaks the truth. Wise words follow them and prosper- deviate from the path at your own risk.


Mitch
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post #36 of 43
8/31/07 at 2:53pm
If you are going to spend any appreciable amount of money buying tubes on EBay, you should get a tube tester. They are not that expensive, and they are very fun! I have taken a risk (knowingly) on some cheap 6SN7's that were supposedly good but I got them and they either tested weak or bad. One even had a short! Not a good idea to find that out in your amp, generally.

Also, the Amperex Bugle Boy EL84 and 12AX7 that live in my ASL MG Head are fantastic sounding. No surprise the 6922's are pricey. I've been trying to score a, RCA Red Base 6SN7 for a reasonable price, but those things go for 10-20x what a normal 6SN7 goes for.
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post #37 of 43
8/31/07 at 2:58pm
The Red Base 6SN7 sounds terrible in my opinion and I would save your money. They also have a little different operating parameters, the reason for their longer life but as to sound, flat, dull and lacking in bass. People think they are good until they try them but the myth continues.
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post #38 of 43
8/31/07 at 3:35pm
Isn't the "Longer Life" of the Red Base 6SN7 a result of it's lower operating parameters so it might not be a "Longer Life" tube if used at 6SN7 parameters?


Mitch
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post #39 of 43
8/31/07 at 3:36pm
Quote:
Originally Posted by jamato8 View Post
The Red Base 6SN7 sounds terrible in my opinion and I would save your money. They also have a little different operating parameters, the reason for their longer life but as to sound, flat, dull and lacking in bass. People think they are good until they try them but the myth continues.
That's good to know! I'll stop trying, especially since I LOVE the sound of the CBS Hytron 6SN7 I have been using.
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post #40 of 43
8/31/07 at 3:40pm
Quote:
Originally Posted by jamato8 View Post
The 6BZ7 preceded the 6DJ8 and works great. In many applications I like it as much and in some more than the 6DJ8.
Nice to hear I didn't give bad advice and the 6BZ7 can be used.
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post #41 of 43
8/31/07 at 3:44pm
Quote:
Originally Posted by jamato8 View Post
I like the 27 mesh plate very much. The Sylvania 1929 to 1932 mesh plate (nos) (the only way they were made then) is better than anything else on the market even all the varieties of that blue tube (nos). :^)
Do you know of any good places to buy these?
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post #42 of 43
8/31/07 at 3:46pm
Quote:
Originally Posted by braillediver View Post
Isn't the "Longer Life" of the Red Base 6SN7 a result of it's lower operating parameters so it might not be a "Longer Life" tube if used at 6SN7 parameters?


Mitch
Yes, they put in support rods and "beefed" up the tube with nice internal construction then pulled down the operating points but if you apply the same voltages as used with normal 6SN7's it won't last any longer and again the sound to me and many others whose ears I trust is eck.

I have maybe 8 nos that I am keeping so I can sell them. If someone wants them that bad I will sell them on Ebay but I will not say they are great sounding or anything else. It will be a tube for sale and nothing more. Some applications were actually built around this tube and although the preamp is ok I still don't think much of it but the operating points are for the red base.
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post #43 of 43
8/31/07 at 4:05pm
Quote:
Originally Posted by Rob N View Post
Do you know of any good places to buy these?
Not any longer. It has pretty well dried up and some of the advertized nos on ebay I could tell were not. Often wrong tube with the box as they changed the boxes every couple of years in the late 1920's and 1930's. I was lucky to get about 6 nos Sylvania 27's from 30 to 1932. I have purchased some used that tested like new and they sound very fine but often they can be noisy do to being gassy. It is often better to put them in a tube tester and let them warm up with only the heater on so that the getter is well activated. This can help at times with a gassy tube, sometimes not but if done before use then the current will not be applied to the plates or grid, depending upon how it is used. I ran mine at 160 volts with 6mA draw and biased at (I can't remember right now).
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