Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ALBATROS1234 on October 05, 2019, 01:41:45 pm

Title: currently in production sharp cutoff pentodes?
Post by: ALBATROS1234 on October 05, 2019, 01:41:45 pm

wondering if anyone is making preamp pentodes? checking around i found jj makes an ef86/6267 which is great but are there any other pentode preamp tubes being made today? i had hoped someone made a new 6sj7 or something. are we only to rely on used pentode preamp tubes? because even though some sellers claim nos are there "really" any such things? i know some people have up scale testers and can verify used/nos tubes as equal in spec, but i cant really verify this "as i am sure many of us cant" and i am at the mercy of the hearsay statements of tube vendors . just wondering if anyone made something new besides 12a**7 and power tubes( i have seen new 6SL7 and 6SN7 as well)

Title: Re: currently in production sharp cutoff pentodes?
Post by: PRR on October 05, 2019, 05:17:21 pm

There are SCADS of virgin from 1960s 6AU6 and similar in warehouses. There was excess inventory when tubes went out of style, and most of that is still around. These were mostly better made than today's production.

6J7 and 6SJ7 should also be super abundant.

Title: Re: currently in production sharp cutoff pentodes?
Post by: ALBATROS1234 on October 05, 2019, 07:07:28 pm

there does seem to be a substantial amount of 6sj7 and 6j7, hell i got a bunch that work well. you would think that someone would make a new production 6sj7 though as popular as that tube was/is .this is kinda what i thought but i was curious. guess i will keep using the oldies but goodies. i actually dont have many new tubes, i was just searching because i hoped maybe a new 6sj7 type might have improved microphonics etc. thank you sir for your reply as per usual.

Title: Re: currently in production sharp cutoff pentodes?
Post by: brewdude on October 06, 2019, 12:32:47 am

I generally expect NOS tubes to be better, more robust and less microphonic, but I’m not as knowledgeable as many that frequent these forums.

Title: Re: currently in production sharp cutoff pentodes?
Post by: ALBATROS1234 on October 09, 2019, 01:17:58 pm

I agree, and I basically use nos or used but in good shape tubes. I only have a few new production ,but I was thinking if I ever decided to market some of my amp circuits , for consistency,   new tubes would be perfect. I like using sharp cutoff pentodes for preamp circuits. Some say the new production tubes are better regarding microphonics. And I have noticed on the handful of 6u8a I have used that many are at least slightly microphonic.