Octal base electrolytic capacitors

Discussion in 'Glowing Bottle Tube Amp Forum' started by radiocaster, Sep 9, 2019.

  1. radiocaster

    radiocaster Poster Extraordinaire

    Posts:
    5,435
    Joined:
    Aug 18, 2015
    Location:
    europe
    I don't know why this idea got scrapped, it seems like it would be perfect for today's amps.

    It was more common on radio and military equipment. I think I might have seen one guitar amp on the net that had one octal cap, but it doesn't seem like it really caught on with guitar amps, They were generally dual (2 caps in one can).

    Relays with octal or other bases were also common.

    In amps I've also seen octal connectors with a cable for connecting the switches and pots to the chassis, or several chassis together.
     
  2. Platefire

    Platefire Friend of Leo's

    Age:
    71
    Posts:
    3,359
    Joined:
    Nov 3, 2003
    Location:
    North Louisiana around Many
    Yelp! I've got a three NOS octal Capacitors. Just unplug the old one and plug in the new one.

    The only thing I can think of why they didn't because guitar amps mostly use large electolytics on the high voltage power supplies. As you know for a traveling musician guitar amps gets hauled around a lot. Sometimes with all the jarring octal power tube get loose, loose contact and the amp then isn't working right. With the octal electrolytics, the same thing would happen
    disabling the amp. So my thought is they wanted the HV power supply to be permanent un-moveable connections that couldn't become disconnected in extreme hauling and moving???
    My best guess! Platefire
     
    Wally likes this.
  3. radiocaster

    radiocaster Poster Extraordinaire

    Posts:
    5,435
    Joined:
    Aug 18, 2015
    Location:
    europe
    I don't think so, it was used on military equipment.

    My best guess is they didn't care what would happen to the guitar amps in 20 years.
     
  4. Wally

    Wally Telefied Ad Free Member

    Posts:
    32,527
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Military situation....that might have the goal of ease of service in the field?
     
  5. Bill Moore

    Bill Moore Tele-Afflicted Silver Supporter

    Posts:
    1,098
    Joined:
    Feb 2, 2012
    Location:
    Silver City, New Mexico
    I think Wally has it!

    In the Navy, the only troubleshooting they expected from us was to change boards, tubes, etc, until it was working. We had Electronic Techs on board ship, and one of them tweaked my old Airline for me, but the myriad different boards, modules, etc, were sent back for refurb.
     
    radiocaster likes this.
  6. 11 Gauge

    11 Gauge Doctor of Teleocity

    Posts:
    10,796
    Joined:
    Mar 21, 2003
    Location:
    Near BWI Int'l
    I wonder what the price difference was to manufacture vs. just the typical cap can. The military no doubt had contracts for purchasing in bulk. It seems like the same thing probably didn't happen within the commercial vein.
     
  7. gusfinley

    gusfinley Tele-Holic

    Posts:
    777
    Joined:
    Jun 11, 2014
    Location:
    SLC, UT
    There was also a tube base socket called Loctal ( Locking Octal ) The center post was like the tip of TS connector and would "lock" in place, but the pins were much smaller and therefore weaker.

    Loctal Base Caps would be awesome for servicing tube amps! ( and for "Sag" swapping!)

    [​IMG]
     
  8. radiocaster

    radiocaster Poster Extraordinaire

    Posts:
    5,435
    Joined:
    Aug 18, 2015
    Location:
    europe
    Of course, but wouldn't that also be what touring bands would want?
     
  9. Wally

    Wally Telefied Ad Free Member

    Posts:
    32,527
    Joined:
    Mar 17, 2003
    Location:
    Lubbock, TX
    Just theorizing...mulling it over. There is a difference between military requirements and demands than in any other situation. I have no doubt that soldered connections are preferable in any situations other than one in which a repair might best be be made in seconds rather than many minutes..at best..with a soldered in cap can. And...the military setting of a needed repair might not be conducive to soldering??? The soldered connections last decades. How many times would an octal fitting need to be dealt with over that time period...
    At any rate, better electronic wisdom than mine came to certain conclusions.
     
  10. radiocaster

    radiocaster Poster Extraordinaire

    Posts:
    5,435
    Joined:
    Aug 18, 2015
    Location:
    europe
    And also octal caps would cost more, as would adding the bases to a chassis.
     
  11. Platefire

    Platefire Friend of Leo's

    Age:
    71
    Posts:
    3,359
    Joined:
    Nov 3, 2003
    Location:
    North Louisiana around Many
    Probably Cheaper using soldered caps rather ones with special connector Caps. Leo was always interested in the bottom line cost factor.
     
    radiocaster likes this.
  12. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

    Age:
    59
    Posts:
    16,413
    Joined:
    Mar 2, 2010
    Location:
    Maine
    And on the other side there are tubes that can only be soldered into a circuit, no plug in option.
    Wouldn't be that hard to build amps with sockets for the caps, then sell the socketed caps as parts.
    Makes for a lot of sockets on the chassis though.
    As far as them getting loose, I have an amp where the builder put big cap can clamps around the power tube bases with a rubber gasket.

    I have a bunch of mic transformers and line transformers with octal bases, out of an old tube mixer.
    Then there are octal connectors between organ and amp, or preamp and power amp.
    Anybody who chooses can do that, no need for the cap manufacturers to fit caps with octal bases.

    Taking it a step further into the ridiculous I had one of the Duncan Convertible 100w heads with all those plug in preamp modules.
    Not octal base, more like computer circuit board plug ins.
    Seem collectible now but when I bought it at Mannys they were dumping them for 1/3 the original price, and the modules were IIRC $25 each. Not that bad an amp, though most alternate modules didn't do anything better than standard ones.
     
    radiocaster likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.