A question about valves/tubes

  • Thread starter Thread starter Jim Lad
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Jim Lad

Jim Lad

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I am finding that about one in four tubes that I buy are quite noisy in my mics.
Spits, sparks, bumps, rumbles and such.
They usually come with all sorts of test results showing that they are in great shape.
Are such tubes still good for amps and preamps or am I just being ripped off?
 
One of so many reasons that I avoid tubes at nearly all costs (except for guitar amps and only a few pieces of tube gear where it actually makes a difference).
 
"It depends...?" Most tube mics aren't using using the same tubes as most tube preamps. If you're talking some starved-pate unit with a 12AX7 which would probably sound exactly the same if you replaced the tube with some carefully placed bent paper clips, then it's probably worth a shot.

That all said -- If you're coming up with nasty, microphonic, inconsistent tubes in the first place, I'd start with contacting the vendor.
 
I've had good success buying preamp tubes from these guys. I went with matched Tung-Sol 12ax7 reissues and all have perfromed great.

I previously bought the GT "Mullard" reissues and 3 out of 5 were microphonic right out of the box. Aspen Pittman is a con artist of the highest degree IMHO. His Chinese-made tubes are shit. Oh, and the phantom power supply on one of my GT Bricks went tits up within the first 6 months too.:rolleyes: I wouldn't give two cents for GT's quality control.

thetubestore.com - Audio vacuum tubes for your amplifier.
 
So if I'm having a problem "Microphonics" in the mic, it will probably be just as bad in an amp?
I have 3 Mullard 12AT7 tubes, two of which are quite marvelous and one is noisy. They are a bit dark but I thought 2 out of 3 isn't bad.
I'm avoiding the re-issues and think they are probably hurting the original brand, somewhat.
There's a German supplier (His photos are all orange) from whom I purchased an ECC801S Telefunken.
I'd have to recommend him just based on this one purchase.
The Chinese tubes which are in the Behringer T-1 and EM T5000 are actually quite impressive where as a third Chinese Tube that came in another mic was just too hot. (all 12AX7)
So I think it's a bit of a crapshoot no matter what the country of origin is.
I was quite interested in the Brick.
Not so good then?
 
Call the Tubestore guys and they will steer you right. They are in Hamilton Ontario.

The Brick is an okay instrument preamp. I use it in front of my Leslie and it does a decent job. I'm less impressed with it as a mic pre.

Maybe I just prefer straight-wire-with-gain for mic pres.
 
Thanks: Maybe there's no way to answer my question without actually buying a valve amp.
All of those old tube testers are marvelous I'm sure but I don't think anyone is actually listening with human ears.
 
Why use tubes which are an antiquated technology, use transistors (in chips) which are so superior in performance (unless you like the nicely rounded-off distortion which tubes give)
 
Get yourself a really nice tube mic and you'll see why.
There are really nice condensers, ribbons, tubes, dynamics and hybrids thereof.
Limit yourself to one if that's what you like.
I'll be trying out a few of the others though.
 
Massive Master said:
...If you're talking some starved-pate unit with a 12AX7 which would probably sound exactly the same if you replaced the tube with some carefully placed bent paper clips, then it's probably worth a shot.

That all said -- If you're coming up with nasty, microphonic, inconsistent tubes in the first place, I'd start with contacting the vendor.
Click to expand...

I see a business opportunity, there...;) And, yeah, I'd be sending those puppies back WHOLSALE if I got a whole batch of tubes I didn't like.

Almost all pre-amp type tubes are microphonic, to some extent (I have read this, do not know it from personal experience except to say my experience supports this.) AFAIK, there is no bench/electronic test to determine a tube's level of microphonics- the only test I know of is the "tap it with a pencil and listen" test, which, given the microphonic quality of all such tubes, rather subjective and thus of limited value except in the extreme.

I wonder: how 'bout a "Microphonic Tube Tester" that would "listen to a tube for it's level of microphonics? I'm thinkin', a tube socket that powers up the tube in whatever way it needs, and a flush-mount pot (that can only be turned with a screwdriver- no knob on it) for "calibration." Inside the tester is a little spring-loaded hammer with an eraser head- you pull a lever that cocks the hammer, then releases it, thus tapping the tube with a pre-determined level of force, always the same.

First-time use procedure would be to put a tube in the tester that you "know" is micro- that is, one that has a level of micro unacceptable to you. While activating the hammer, you adjust the calibration so that that particular tube is shown to bring the meter to "5" on a scale of "10." Then, any tube you test would be rated, compared to that tube. It would take most of the guess-work out of determining if a tube was "micro."

Would it work in the real world?
 
Jim try this ... proaudiotubes@aol.com ... Christian Whitmore is very knowledgeable sells only tested tubes and will talk to you about any questions you may have.
 
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