Tube Lab

We're of course talking about noise! But believe it or not some circuit topologies or designs can make tubes mircrophonic or noisy, so be very careful when buying your gear.
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[@cobar5342]

Another great video Jim. I always learn something from you. From Down Under

[@iampuzzleman282]

I was hoping to get the number three problem. Maybe this is a three-part video. You guys doing a great job with your stuff😊

[@TheJoyofVinylRecords]

Great stuff. Thank you!

[@frankgeeraerts6243]

Flashing filaments ...............causes panic by a lot of customers ....I always have a smile .

[@ionflier4183]

I see a Fiio X5 gen1 on the bench , great little device!! 😎

[@tubelab194]

Good eyes! Yes I've owned that handy Fiio DMP since they came out and I've owned many later generations as well, sold them all and kept the first one. Sounds the best and very handy for the testing bench.

[@frankgeeraerts6243]

Nice review of the subject of noise... To high the heater voltage can/will also make a good tube noisy ... Transistors are also sensitive to microphonics ( YBA even damped his low signal transistors ) Some ( nos ) ube type were specialy designed for very low noise and microphonics ( medical, mil , very small signals , tape heads , microphones etc ) ......ECC808, 7025 , etc Some tuibes have micafingers on the cathode.........ECC xxx ( not all )......ECC88 /ECC188/CCA.... but not the favoured used by the audio industry in many pre-amps 6922/E88CC ( because of the big stock and dsiponibility at low price )..........they are prone to HF ringing ( most audiophiles tend to believe it is more detail !!! ) you must select them if you use thses . Good idea is to ,mount input tubes and low signal tubes sockets on dampers as seen in older tube gear ( tape recordres, ,phono , radio etc ) A tube that is slightly microphonic can be used in the following stage . Very assuring to buy tubes with confidence at places as yours .... ALL this time consuming but a happy customer will be there forever and return ....in the long run both customer as well as the seller will benefit. Kind regards

[@moodyga40]

Tubes are the best ❤

[@frankgeeraerts6243]

The 6FQ7 is the same tube as a 6CG7 ....but WITHOUT a sreen between the triodes..........

[@michaelstevenfriedlander4583]

The #1 problem with tubes is: normal tube tester only detects 4 out of 10 defects. Normal tube tester is less than 50% accurate. Big problem.

[@tubelab194]

It is true that tube testers don't specifically detect all problems, however in the hands of a skilled tech certain tests can indicate another problem. For example, when we are testing power tubes on our custom tester, we watch for grid bias supply stability, our supply isn't regulated and what that allows us to watch out for is potential G1 issues that might cause other problems. In fact G1 issues probably account for many of the noise issues in all tubes. If all tube sellers made a final "live" test in a well designed circuit, that would catch many problems before a tube even arrived in the customers hands - that's our policy and it saves us and our customers a lot of trouble later on.

[@louiesipes2257]

Just a couple years experience with tubes…..whistles are common and I generally don’t care unless they get intrusive while music is playing. That said, what’s your opinion, worn out or just normal aging? Popcorn gets pulled immediately…

[@tubelab194]

In all of my years working with tubes, I've never heard a tube whistle. That's definitely a new one for me. I would suspect one of two things, the amp design is not standard (a lot of badly designed gear has been showing up for sale - especially in the last two years), or a modern Chinese tube - most of them aren't very well made. I'd be interested in knowing the amp and tubes you are running.

[@louiesipes2257]

@@tubelab194 😂That’s just what I call it, maybe a high pitched whine? The pre is a Van Alstine, sounds great when tubes are fresh.

[@tubelab194]

@@louiesipes2257 probably the circuit being used, there are circuit topologies that will take a normally quiet tube and make it prone to noise issues. In my design work I avoid those circuits. I didn't have enough time Friday to include a full discussion on this problem and I see it crop up fairly often.

[@louiesipes2257]

@@tubelab194 Well, not sure about that….I get a few months out of ‘em before any issues. Silence for months and then…..nevermind.