EBAY AMPLITREX TESTED TUBES BEWARE!

[selloutrr]

OK I've been looking at purchasing some tubes. It's old news I own an Amplitrex AT1000 tube tester, and when I purchase a tube that is tested I expect it to be within a certain exceptable range when I recieve it. This has lead many tube seller to not sell me tubes, that's fine I'd rather not waste time or money.

Lately I've seen a boom in Amplitrex tested tubes on Ebay. Which is a good thing for both parties involved. I'm happy to see the tester is taking off.

The problem more times then not the seller is lying about owning an amplitrex.

I contacted a seller yesterday about a quad of matched tubes. In the auction they stated the tubes were matched on an amplitrex but gave no values or measurements for the tubes. At several hundred dollars I contacted the seller and requested the data sheet, that is standard with every Amplitrex test. The seller declined saying it would take to much time. Which I find concerning since he has already tested the tubes and the Amplitrex auto saves the data in backup.

I guess all I'm saying is if you plan to buy tubes, Amplitrex is the way to go, however buy smart and ask to see the data sheet and curve trace. It's not a hastle or problem to present the data, at least from my point of view, but what do I know I still believe in doing things right the first time and customer service. I give a copy with every tube I test, good or bad it is what that tube is. Just because some one says something don't take their word for it, ask for proof. That is the best part of the Amplitrex. Results you can read on paper.

hopefully no one here has been burned.

[xtian]

Cool. Thanks for the heads up. Can you post an example tube trace? Interested to see what it looks like.

[selloutrr]

Sure.

Each test in Computer Control Mode give a spec sheet based on the tube under test which shows the parameters of the test. Similar to a data sheet in a tube manual.

The second sheet gives the test results. This test sheet shows the controls ( spec sheet ) in the left column and the Test results to the right. If the tube has multiple sides such as a 12AX7 / ECC83 it will show the control spec / test A (side) / test B (side)

the additional test results are Optional
1.) Curve trace you can plot up to 10 curve traces. Though much over 5 is over kill and often muddies up the detail.
2.) noise test. It plots the noise though it's difficult to read if you aren't sure what you are looking at. During this test I "Y" the test tone to an Oscilloscope, and amplifier external of the Amplitrex where I can listen to it on a speaker or with headphones. Personally if the tube has microphonic noise issues I then test it again on the VTV Small Charactizer for noise.

Attached are some random sample I have on this computer. These test results are not in "fixed Bias" mode.

It's possible to also test tubes on the amplitrex using "stand alone" mode where the unit is not connected to the computer. these test results are given in % where a 100% is the NOS some tubes test above 100% many well below. I'll take some pictures of stand alone mode so you can see.

[selloutrr]

here is a link to the company's website photos. I don't have any on this computer.

top row far right shows the stand alone test results in %

http://amplitrex.com/photos.html

I can also burn test results directly to labels making it easy to label tube cartons. This would also be an exceptable form or documenting a tube test. - pic attached.

[martin manning]

sellout, thanks for the warning and posting the test sheets. Very useful information, and the Amplitrex is truly an awesome piece of gear!

[selloutrr]

I hope it helps.
With the cost of NOS tubes going up it's become to tempting for dishonest people to make a quick buck at others expense.

Don't be afraid of purchasing Amplitrex Tested tubes!!!
Just be a smart shopper. If the seller can not produce at least one form of the test results I've posted - buyer beware.

Any tube that tests good on an amplitrex is a great tube. It's so exact that most test results of 75%+ are more then OK for guitar amplifiers (fender, Marshall, etc). I'd personally shoot for 90% or better in TW builds.

Happy Building!