Manley SHRIMP - Manual (Page 11)

TUBE FAQ
A few general vacuum tube all-too-frequently-asked questions answered.
Excerpts from the manleylabs.com FAQ:
FAQ #16. Do you sell tubes?
I don’t know what you’re talking about.
FAQ #16a. I need to retube my Manley preamplifier. Do you sell tubes?
Sorry. Just kidding. Yes, of course we do. We have about 100,000 tubes in stock of the several major types we use.
FAQ #16b. Why should I buy tubes from you?
We are only as good as our worst tube. We are very selective about which tubes we use in Manley products and we
have several different testing and burn-in jigs to test for certain parameters which will be most important for that
tube in a given circuit. We will test and select a tube set for you that will be optimized for your Manley piece of gear
and in most cases, your tube set will actually be tested in another one of what you have.
FAQ #16c. Are tubes expensive?
Not especially. Although I might have made a killing in the stock market had I invested the money I instead put into
finding and stocking these large quantities of tubes ten years ago when the USA military were dumping their stocks
of NOS JAN vacuum tubes. Seriously, there is the stocking cost to consider in the cost we must charge, development
charge of the computerized test jigs we built, then more importantly the time it takes one of our guys to run a little
tube through its qualification procedures. Remember, a given tube cannot be improved during testing. It is the way it
is, and one hopes it stays that way. It can only be selected, and in selecting that tube that will work really well for
your piece of gear, we probably had to throw away several. In some cases we might have had to go through 30 tubes
to find the quietest one, or the one with the lowest microphonics, or the one with the best internal matching,
depending on what parameters are important for that circuit. That is all factored into the cost somewhat, but no,
overall, we don’t charge enough for replacement tubes.
FAQ #16d. NOS? JAN? What does that mean?
New Old Stock. Joint Army Navy. Yes our military used to use vacuum tubes. As long as the glass doesn’t break,
tubes are impervious to a nuclear explosion’s electromagnetic pulse unlike little silicon devices whose little junctions
would go poof!
FAQ #16e. Good to know. How long do tubes last?
Some of them are dead out of the box. Some tubes don’t make it through burn-in and after a few days they just go
noisy or quit. Sometimes UPS sabotages our shipments and after all our testing efforts the tube arrives broken at
your place. Sometimes a tube decides to end it all early and intentionally misbehaves after a few months. Other tubes
are real troopers (like my 98 year old neighbor) and run strong for 30 years. We have documented cases of power
tubes in Manley amplifiers going over 60,000 hours non-stop in recording studios 24/7/365 without a re-tube. In one
case in particular, the amplifiers were never turned off and had their own dedicated air conditioning for the amplifier
rack they lived in. This certainly contributed to their long life.
11
INPUT
TUBES
12AT7WA
OUTPUT
TUBES
7044
TUBE LOCATOR DRAWING
PRINTED CIRCUIT BOARD
AS VIEWED FROM FRONT