Unbalanced SEX, please help

[Doc B.]

Yes, if you hear differences please let us know. I think there are really only a few different types of 6DN7s, though there are many different brands stamped on them. I haven't heard a lot of difference among them, though I ended up with some Tung-Sols in my own S.E.X. kit which I though had a tiny bit more of the Tung Sol family sound than the rest (a bit more bass and body, possibly at the expense of articulation).

As for other tube types, I have never warmed up to the 6EM7. I think maybe the high output impedance of the small half makes a sonic signature that is not my thing.

[Paul Joppa]

The 6DN7 has been in the Bottlehead lineup from before it was called Bottlehead, so there has been some chatter but much of it is years old.

For the most part, only very slight differences have been found among different brands. There are some different constructions, so you would think there might be differences but few have been reliably heard. I suspect Fred_P just got a bum individual tube.

The only difference I recall being agreed upon was a slight preference for the most modern, "coin-base" versions. Like most of the constructions, they were sold under more than one brand name but I'd bet they all came out of the same factory.

We have usually preferred the 6DN7 to the 6EM7/6EA7, which can be used in the SEX amp is a few changes are made. Doc and I agree that this is most likely due to the difference in the low-power driver section, but of course it's hard to get solid evidence of that.

[JC]

I would be inclined to think that you both guess right; undoubtedly there were truckloads of this tube manufactured at one time during the B&W TV boom, but I can certainly see the bulk of them being made by one manufacturer and sold under a variety of labels.  That would have been very common during the period when they were a hot item.

And, it would certainly account for some consistency from tube to tube.