Tubes Asylum: RE: Agreed, it's not a 1578 unless it's stamped "1578" , but... by dimsal

Hi Paul,

Thank you for your comments, but let me ask you where did you get the idea that I advertise the tubes I sell as 1578? I just re-read Brent's page (http://www.audiotubes.com/6sn7.htm) with his quote and the one I put in my listing and I don't see him mentioning that he refers particular to 1578. Look for yourself, there's no info about 1578 at all on that page.

I'm not sure how many different 6H8C's Brent personally had experience with.. I've had 6H8C's in my possession manufactured in 50's, 60's, 70's, and 80's and frankly there's very little difference in sound quality they all are good. And AFAIK they all have the same internal structure, except some has holes in the sides of the plates and others don't.

I personally saw 1578 marked only on some of the latest 70's and 80's. Before that the same exact tube was just 6H8C. 1578 designation was introduced later in the 70's and these tubes were specifically manufactured for atomic industry. They do have very good live though 5000 hours. So, the ones I'm selling are the same tube but manufactured in 50's and 60's when there was no 1578 in existence.
Also 6H8C were manufactured in Moscow on MELZ factory (Moscow Vacuum Tube Factory) and 1578 were manufactured in Saratov.

My father is electronics engineer who spent 40 years working with vacuum tubes in Russia and he knows this stuff first hand.

I've listened both 1578 and regular ones, and personally I don't hear any differences in SQ between the two. Of course, as we all has individual/subjective experience of all things, especially in sound reproduction, YMMV.

Anyway, please I'd really appreciate if you could send me the source of your info regarding Brent's comment mentioning that he particular speaks of a 1978 manufactured tube? I'd be interested in reading it.

BTW, I already sold all tubes, but will be expecting some more to arrive next month.