National Union 6SL7 Black Glass Posted on September 9, 2020 by tubemaze (13 votes, average: 4.23 out of 5)Loading...No reviews found on the web. Read our reviews.Share this post:
Very interesting tube, it’s one of my favorite tubes now. So after trying hundreds and hundreds of tubes, it’s so awesome to find something that is very special. First of all, the tube looks great right away – the black glass is never a wrong choice for tubes – makes it look very serious. The sound is something else – very transparent, and I mean very transparent, quite similar in sound to NU 6F8G Round Plates, which is no surprise considering exactly the same plate and support structure. Being this transparent and airy, the tube remains warm – which is a great plus; otherwise, it would become Telefunken and be very clinical sounding. None of that here. Just all musical instruments on a platter, air around them, and a huge, 3D soundstage. Add great tight bass and this tube is a real winner. For now, this tube even replaced Brimar 6SL7 in my amp, which is not an easy thing to do.
I compared regular NU 6SL7 and their JAN CNU military version. The tubes looked and sounded exactly the same.