Tubes Asylum

RE: 7058

68.55.22.7

Dave Pogue

In Reply to: RE: 7058 posted by adaug on May 06, 2012 at 12:04:36

Certainly in Aesthetix Calypso and Rhea models.

Follow Ups:

7058 requires 12V filament... - Interstage Tranny 16:23:17 05/06/12 (5)
...strictly designed for 12V to 13.8 V filament heaters. They worked great in mobile (12V car battery DC filament) applications. These are ruggedized tubes...
- RE: 7058 requires 12V filament... - Jim McShane 16:42:28 05/06/12 (4)
  Here's a little tip - most RCA 7058s are just 12AX7s that are numbered 7058 - they have a heater CT and plug right in and work perfect in 12AX7 sockets.
  - RE: 7058 requires 12V filament... - Dave Pogue 10:24:07 05/09/12 (3)
    Jim, since my GE and Westinghouse 7058s appear absolutely identical to the RCAs, are they also just 12AX7s? And do you know why did they bothered with the 7058 nomenclature in the first place?
    - RE: 7058 requires 12V filament... - Jim McShane 13:27:10 05/09/12 (2)
      Hi Dave!
      
      Try them out and see - you can't do any harm. They may have been made by RCA and relabeled.
      
      The 7058 was the designation for the tube in mobile radio service. It had a wide range of acceptable heater voltages so it could be powered off auto/truck charging systems and was "ruggedized". Since it was used off 12-15 volt systems there was no need for a heater center tap.
      
      I suspect they found it more economical to build 12AX7s to the 7058 spec (but with a heater CT) than to run the production separately - especially since the 7058 was a low volume tube. They did that with 6BQ5s too, they were 7189s labeled 6BQ5/EL84.
      - RE: 7058 requires 12V filament... - Dave Pogue 18:57:47 05/09/12 (1)
        
        In Reply to: RE: 7058 requires 12V filament... posted by Jim McShane on May 09, 2012 at 13:27:10
        
        I've had mine for months and, assuming there was no basic difference between the GEs and RCAs since they looked identical, have been using them interchangeably, determined solely by how they tested -- especially for noise and microphonics --on my George Kaye tube checker. So I guess I'm glad I didn't know that some of them were 12AX7s and some might really be 7058s :-)
        
        RE: 7058 requires 12V filament... - Jim McShane 06:21:30 05/10/12 (0)
        
        In Reply to: RE: 7058 requires 12V filament... posted by Dave Pogue on May 09, 2012 at 18:57:47
        
        "So I guess I'm glad I didn't know that some of them were 12AX7s and some might really be 7058s"
        
        But as you now know, it's really a moot point - unless 7058 is your lucky number!

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