TUBES 6922 pinched waist

Gellis1, I thought I'd add that Andy @ Vintage Tube Services does testing as well. He has a lot of the old testing equiptment-pictures on his web site- dating from 1920-1960. For $6 a tube, he can test your tubes for use-(how close they are to being new), shorts, etc. and tests them in a testing booth for microphonics. I had him test a batch of new 1976 7308 Jan Sylvania tubes that I stumbled upon in my area. He matched the survivors, which was about half of the tubes sent, labeled them and sent them back. Also, if you do buy tubes from him, he backs them up for 1 yr. Good hunting! Stan

What does the falcon mean on the Seimens, Does it tell you the age or quality of the tube? It looks like the letter H in the middle of an S Does it mean they are Halskes?

Talon4,Thanks for explaining the sheild.I have only 2 tubes in my pre they are seimens CCa type.They sound great. With only 2 I can play with different tubes.I just tried some Amperex 6dj8 Bugle Boys white lettering.They lacked bass and were harsh in the highs.I hope the PQs are better.

Yes, my 7308 vacuum tubes have a shield around the "pq" on one side of the tube. On the opposite side of the tube, it's labeled "Amperex 7308 USA." They made a Holland version of this tube, but I've never tried it. The Holland version is sapposed to be a little sweeter. I've noticed that these tubes are starting to get expensive as well. I've got 4 matched sets of 7308 Amperex PQ white label with shield in my preamp. With that many tubes needed, tube rolling is kind of out for me.

Talon4,When you say shield are you talking about the shield around the PQ on the outside of the glass?

Try Andy @ Vintage Tube Services. His phone number is on his web site-www.vintagetubeservices.com He should be able to give you the history of pinched waist tubes. He told me that it was a further attempt by some vacuum tube manufacturers to reduce microphonics. A roller was used on the glass to give it the pinched look and they were only manufactured for a few years. I think that if you can find any, they will be outragously priced. Andy told me that he has only run across one pinched waist tube. As far as 7308 tubes go... I've been told that they were an attempt by manufacturers to make a hardier tube than the 6922. I run 7308 Amperex white label/shield tubes in my preamp. I like their sound, but I haven't done that much tube rolling. I believe that they are a tougher, longer lasting tube. Andy should be able to give you a seasoned opinion of 7308's as well. When it comes to knowledge, he's the man! Good luck! Stan

With my amp (Audion Silver Night MKII), my description of 6922 types would be quite different than that described in Joe's Tube Lore. As Tvad writes, that is one man's comprehensive viewpoint. A valuable one indeed, but not categorically applicable.

Gellis1, you will have to experiment with different tubes in order to find what works best for you. Yes, that gets pretty expensive when it comes to NOS tubes. But there is no end-all/be-all tube, not in terms of something that will behave the same way in every component, let alone to two different sets of ears.

Unlike lucky Tvad, I have purchased a number of microphonic 6922's. Buy ONLY from a reputable seller with a warranty, or this venture can potentially become far more expensive than you had anticipated.

All the best,
Howard

Do you know of a reputable tube seller that will sell pinched waist tubes to anybody.Some do not sell to you unless you buy their gear.

Tvad,I have been to that site and thats what turn me on to the pinched waist tube.He says the pinched waist is Yeow! My reference tube.He goes on to say the shape of the tube helps reduce microphonics,quite the contrary to some of the post.Are the chances of a pinched waist tube being microphonic any greater then a 6922 PQ?

The 6922 PQ's that Tvad references are top-flight, IMHO

Thanks Are the 7308 PQs any better sounding then the 6922 PQs

OK, here is what I suggest. While it applies generally, it is particularly true f rthe tubes you reference. Buy only from a relaible dealer of tubes whom you know trust and/or who will trust you to return them if needed. These can be just fabulous sounding tubes from my experience but can be microphonic to an extreme. I had a couple the sounded fantastic in Kora Eclipse that I had, but I had another pair that looked identical but rather sucked. At the price thse command, you want to be sure you can return them.

I am not interested in orange globes.My question is are the White lettered pinched waist Amperex worth Tracking Down.I have the Pathos Logo,tube pre and solid state power.

I suggest that you look into some cap swapping. The orange globes are not really a night and day different tube in nature, but if you have good caps, and a sound design, the BB's are about as good as it gets in a 6DJ8. Of course tubes are not linear, so they all suck compared to good FET circuits in the accuracy department. That said, coloration, while not accurate, can be more pleasing than an accurate reproduction...

I just installed them a week ago and have no doubt that they sound great. One is a Stromberg, one is Amperex PQ. Soundwise, you can't tell a difference.
BTW - I do not like Bugle Boys. Almost anything else is better. Especially orange globe 6dj8's.

Be careful of the flavor of the month tube trap. If you can use 6DJ8's, and have new gear, or improved caps, Bugle Boys are about the best there is, if you have old gear, Telefunkins, or the Telsa tubes made on the old Telefunkin machines are about as good as it gets because they are bright and compensate for crappy capacitors in old gear. Do remember though that opinions are like a$$.... and they all stink!

Two things:

1. Bad news: the word is that they are almost all monophonic. (amplify environmental vibration).

2. Good news: They cannot be faked. Only Amperex made anything that looks like them.