Results 1 to 7 of 7

Thread: confusing extra speaker jack

  1. #1
    Supporting Member Randall's Avatar
    Join Date
    Jan 2013
    Location
    Cape Coral, FL
    Posts
    2,275
    Thumbs Up/Down
    Received: 443/0
    Given: 81/0
    Rep Power
    9

    confusing extra speaker jack

    Who uses an extra 8 ohm speaker as shown on the original schematic on a 5E3 with an 8 ohm output transformer? I have a MercMag FTDO-59 that I awaiting an answer on this question also.

    0 Not allowed! Not allowed!

  2. #2
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    11,500
    Thumbs Up/Down
    Received: 1,434/21
    Given: 3,592/8
    Rep Power
    22
    What is your concern/confusion? That you will have a 4 ohm load on an 8ohm OT secondary? That was how Fender did it on most of their amps for decades. Their output transformers were very robust and they were not concerned with impedance mismatching. They just added an extra jack in parallel with the speaker jack so you could add another speaker. When you used the ext.spkr. jack you would always end up with an impedance mismatch.

    0 Not allowed! Not allowed!
    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

  3. #3
    Supporting Member Randall's Avatar
    Join Date
    Jan 2013
    Location
    Cape Coral, FL
    Posts
    2,275
    Thumbs Up/Down
    Received: 443/0
    Given: 81/0
    Rep Power
    9
    Quote Originally Posted by g-one View Post
    What is your concern/confusion? That you will have a 4 ohm load on an 8ohm OT secondary?
    yes that's it basically. Mercury Mag recommends not using the extra speaker, but say that Fender did it forever. But I think their concern is more about tube life.

    0 Not allowed! Not allowed!

  4. #4
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    31,726
    Thumbs Up/Down
    Received: 1,609/7
    Given: 0/0
    Rep Power
    54
    Oh that isn't an issue either really.

    All the impedance mismatch does is push the signal down the tube curve. This isn't like trying to run a solid state amp into a 1 ohm load or something. Mercury wants to sell you a transformer.

    0 Not allowed! Not allowed!
    Education is what you're left with after you have forgotten what you have learned.

  5. #5
    Don't forget the joker g1's Avatar
    Join Date
    Feb 2010
    Location
    Canada, somewhere north of Fargo
    Posts
    11,500
    Thumbs Up/Down
    Received: 1,434/21
    Given: 3,592/8
    Rep Power
    22
    They may be concerned about tube life. But they don't sell tubes, they sell transformers. So what they should be concerned with is selling you their more expensive transformer with multiple impedance taps.

    0 Not allowed! Not allowed!
    Just because they don't have tubes doesn't mean they don't have feelings! - glebert

  6. #6
    Old Timer
    Join Date
    May 2006
    Location
    Chill-Ville, VA
    Posts
    3,055
    Thumbs Up/Down
    Received: 612/6
    Given: 1,128/9
    Rep Power
    17
    No, just buy more speakers! Why not just plug it into two 16ohm cabs? 5E3 stack, anyone? And no mismatch. My Concert sounds incredible through 2x15 + 2x12... probably overkill, but fun! I don't recall who here told me I could do that - use two speakers or cabs that are double the nominal impedance, one speaker/cab per jack.

    But I've been mismatching my Bassmans for a few years. As stated above, I wouldn't worry too much about it.

    Justin

    0 Not allowed! Not allowed!
    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

  7. #7
    Supporting Member Randall's Avatar
    Join Date
    Jan 2013
    Location
    Cape Coral, FL
    Posts
    2,275
    Thumbs Up/Down
    Received: 443/0
    Given: 81/0
    Rep Power
    9
    Well, I bought 2 sets before I ever asked this question. Mercury cites tube life and the possibility of one shorting and taking out the OT.

    0 Not allowed! Not allowed!

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Extra gain stage from extra triode
    By Spitfireb in forum Mods & Tweaks
    Replies: 3
    Last Post: 11-04-2010, 07:33 PM
  2. Replies: 4
    Last Post: 03-19-2009, 12:35 PM
  3. Replies: 4
    Last Post: 07-08-2008, 03:04 AM
  4. Confusing problem here...
    By Arthur Dent in forum Debugging Your Build
    Replies: 6
    Last Post: 04-02-2008, 02:07 PM
  5. Extra speaker cabinet
    By blackwood in forum Cabinetry
    Replies: 8
    Last Post: 01-19-2007, 02:09 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •