Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: rzenc on July 30, 2013, 04:22:19 pm

Title: 6SJ7
Post by: rzenc on July 30, 2013, 04:22:19 pm

Hello!

I'm about to build a new project and the schem calls for it. I have never tried this tube and was wondering if you guys have experience with it?

I also don't have any on tubepiles and will need to buy some. Do you have a suggestion regarding manufacturers?

Are you aware of possible substitutes/electrically equivalent?

All input greatly appreciated!

Best Regards
R.

Title: Re: 6SJ7
Post by: DummyLoad on July 30, 2013, 08:08:37 pm

RCA 5693 is an industrial direct replacement. 6J7 is the predecessor with lass-steep slope and arguably better for audio; my favorite 6J7 is the RCA. 6SJ7 are can be/become quite microphonic. i'd suggest you shock mount the socket with some rubber o-rings or something similar. the 6SJ7GT-MR by tung-sol is a glass version with a mesh plate and they are VERY rare and difficult to shield, but damn they sound nice in a guitar amp, if you can find a working copy at a decent price, you won't be disappointed. next on the favorites list is the 5693 the RCA and national union 6SJ7 are desirable as well.

some say that 6SJ7 is/are similar to the EF86. if i need a pentode front end for a guitar amp - the EF86 is my go-to tube. i

haven't fooled around enough with 5879 to form an opinion, except that they can be very microphonic. 

another cool pentode is the EF40, however it has a rim-lock base and they are hardly a mainstream socket, + becoming increasingly difficult to find.

we can't forget the workhorse 6AU6 - a decent tube, but can have too much gain in some circuits. the 6AK5/5654 is another with similar characteristics to the 6AU6, some forum members here have made statements as to liking the 5654 over all.

--pete 

Title: Re: 6SJ7
Post by: DummyLoad on July 30, 2013, 08:11:36 pm

almost forgot... avoid the 6SH7.

--pete

Title: Re: 6SJ7
Post by: rzenc on July 31, 2013, 10:30:44 am

Thanks for all the info Pete!!

It's going for a rack mounted bass preamp that I want to try. Schem attached. Sent ya pm.

Best Regards

R.

Title: Re: 6SJ7
Post by: DummyLoad on July 31, 2013, 04:35:19 pm

replied to your PM... plan looks nice. definitely lots of contouring possibilities there...    :icon_biggrin:

respectfully,

--pete