... How to select tubes for line level preamp ...

DeKay

These came with the unit when I bought it...

This is the info printed on the tubes: (2 of each)

(In silver lettering): USA, above 12AX7A (in a thin silver oval)
                                  RCA (in gold lettering), else where on the tube
                                  Other info on tube worn so it can't be interpreted

(in gold lettering): EF86 6J32P Made in Russia
                                 SVETLANA

AND You think /suggest?

Vintage RCA (Black & Gray plates) do have extended HF's for a 12ax7, IMO (more than the Telefunken and Mullard's I've used).

Old production Holland 12ax7's do also, but they are really expensive now.

Old production Sylvania 12ax7's have gobs of HF, but they are lacking the mid's and LF's that you like.

You might try a new tested pair of the Russian EF86's (old production winged C/SED are still available for $40/pr) in the event that yours have lost some HF extension.

Old production EF86's are also currently super expensive.

Remembered I used the EF86's in a couple of guitar amps that I was retubing for a neighbor for which I pulled a Telefunken EF86 from an old Pilot pre/tuner (don't really know how they sound in HiFi gear).

You might check prices on RCA 12ax7's (I'd look for new testing old organ stock to save money as the Baldwin (Conn?) labeled tubes were supposedly thoroughly screened for their intended purpose).

Not familiar with new production 12ax7's.

Oh, and here is a blurb I placed on favorites and forgot to include in my previous post.

https://www.audioshark.org//pre-amps-9/wolze-triode-line-level-preamp-4421.html

DeKay

DeKay

... thanks again Bud... Be Well, Best Wishes. Bill

Check out Brent Jesse’s site and click on the 12au7 for lots of sound characteristic description of the tubes he offers. 


https://www.audiotubes.com