The most microphonic tubes, in the world!

[mcandmar]

I stumbled across these interesting little tubes, the Tesla 1L33 made in Czechoslovakia. I got two sets of them, one are Tesla boxed, the other set came from the darkest depths of soviet military surplus and have the usual brown paper wrapper. The military surplus also seem to be marked with paint on the tip of the glass.  The 1L33 is a clone of the 1S4 tube so the Quickie can be easily adapted to run them by disconnecting pin A1 and B1 to reconfigure the filament heater layout.

They have one interesting feature in that they have a small window in the plate so you can see inside, and what a shock it was to see those filaments glow! I had gotten used to the idea Quickie tubes don't glow but in reality they do, you just cant see it normally.

The build quality is pretty terrible, when you line the four up side by side the heights of the internals is all over the place, and the plates look like somebody formed them around their pinky finger.  There is one issue though, they are hilariously microphonic.  If you flick the tube with your finger they ring loudly and after a few seconds the ringing will fade out, then fade back in, and out, and in, and out, and in.  No exaggeration i went and made a cup of coffee and came back to find they were still oscillating. If you should happen to be using a stepped attenuator on your quickie good luck to you, it will sound like a wind chime whizzing around inside a tornado.

The best part, or the punch line if you like is that they actually sound really good, provided you can stop them ringing!  I actually really like them, they sound different to other tubes i have tried, but yet they dont seem to be missing anything in the highs or lows.  They are probably heavily distorting the signal or something i cant put my finger on, but they are a fun little tube to listen to, i used them in my Quickie headphone amp for a few weeks and never felt the need to switch them out. @ $2.50 per tube i highly recommend you give them a try, just remember you have to reconfigure the filament heater wiring before installing them.

[Natural Sound]

There are several threads here in the quickie section that discuss treatments for microphonics issues. Perhaps one will work for you.

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[Grainger49]

I would have to say you win the world's most microphonic tube story.  I may have the runner up.

When I bought an ARC SP-14 I sold my Counterpoint SA-1000 preamp to my buddy Doug.  Doug, for some reason, said it needed a new 6DJ8 for the line stage.  He found a GE at a TV shop in Asheville, where he lived, and both he and his wife loved the ambiance that this tube had. 

We visited and when he turned the preamp on after a few seconds it made a ringing sound that sounded just like a small triangle being struck once, "pingggggggggggg".  The ringing died out in 6 or 7 seconds.  But it sounded just like a triangle.

We settled in to (can't come up with the singer's name) Angel.  The hall sound was extraordinarily rich.  It was lush, sounds washed over you and wrapped around you.  After a drink or two I looked at him and said, "The triangle is the the mute relay 'picking' and the tube ringing."  And that is what it was.

But the tube was extremely lush.  It was glorious to listen to.