Results 1 to 6 of 6

Thread: 1964 Vox AC30 Celestion Silver Bells measure 11 ohms

  1. #1
    Member
    Join Date
    Oct 2012
    Location
    Austin, TX
    Posts
    80
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8

    1964 Vox AC30 Celestion Silver Bells measure 11 ohms

    Hey guys. So I have an old Vox AC30/6 Treble on the bench, and I just measured the speaker impedance and itís 11 ohms. Thatís 2 8 ohm speakers in series like youíd expect in a Vox. So should I connect the speakers to the 16 ohm or 8 ohm tap of the OT? Itís closer to 8 ohms, but itís supposed to want 16. Does it really matter when itís in between like this? OT is an original Parmeko and speakers are original too.

    0 Not allowed! Not allowed!

  2. #2
    Member
    Join Date
    Oct 2012
    Location
    Austin, TX
    Posts
    80
    Thumbs Up/Down
    Received: 0/0
    Given: 0/0
    Rep Power
    8
    So I read that 16 ohm speakers usually measure between 10-12 ohms. Iíve never had that low of a reading. But according to the internet, itís normal and I should go with 16 ohms. Thoughts?

    0 Not allowed! Not allowed!

  3. #3
    Member Jon Snell's Avatar
    Join Date
    Aug 2015
    Location
    Jurasic Coast, England
    Posts
    175
    Thumbs Up/Down
    Received: 56/0
    Given: 7/0
    Rep Power
    5
    Use 8R tap with two 16R speakers wired in parallel and 16R tap for two 8R in series.

    0 Not allowed! Not allowed!
    Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

  4. #4
    Lifetime Member Enzo's Avatar
    Join Date
    May 2006
    Location
    Lansing, Michigan, USA
    Posts
    33,496
    Thumbs Up/Down
    Received: 2,543/7
    Given: 0/0
    Rep Power
    57
    You didn't measure impedance, you measured resistance. Two 8 ohm speakers in series is 16 ohms, regardless of the DC resistance. DC resistance usually measures lower than nominal impedance.

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

  5. #5
    Supporting Member
    Join Date
    May 2006
    Location
    Staffordshire UK
    Posts
    3,880
    Thumbs Up/Down
    Received: 599/1
    Given: 556/2
    Rep Power
    19
    Quote Originally Posted by evil79 View Post
    Hey guys. So I have an old Vox AC30/6 Treble on the bench, and I just measured the speaker impedance and itís 11 ohms...
    How did you measure impedance? It requires a special meter, and for a speaker, will vary significantly according to the test frequency used.
    Maybe you meant resistance rather than impedance, the former being lower than the latter. 11 ohms resistance seems a bit low but theyíre rare models so who knows. Do both speakers measure the same?
    Whatever, without any other evidence to the contrary itís probably best to assume that theyíre wired up correctly.

    1 Not allowed! Not allowed!

  6. #6
    Supporting Member
    Join Date
    Mar 2018
    Location
    Germany
    Posts
    3,241
    Thumbs Up/Down
    Received: 2,360/1
    Given: 1,343/2
    Rep Power
    8
    I measured a number of mid sixties AC30 speakers. DCR varied from 6.3R to 6.7R. So you should get around 13R for both speakers in series.
    Is your meter accurate, calibrated and battery fresh?

    Speaker impedance is always higher than DCR.

    0 Not allowed! Not allowed!
    - Own Opinions Only -

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Hot Deluxe III ? output xmer , reading 79 ohms &103 ohms to center tap. Is it bad???
    By 1ampman in forum Maintenance, Troubleshooting & Repair
    Replies: 2
    Last Post: 02-01-2017, 04:03 PM
  2. 1964 Vox AC30 Treble Model
    By 767400 in forum Schematic Requests
    Replies: 4
    Last Post: 12-10-2015, 09:23 PM
  3. Vox JMI AC30 (1964) Servicing
    By Marky in forum Maintenance, Troubleshooting & Repair
    Replies: 8
    Last Post: 01-29-2010, 09:09 PM
  4. Vox AC30 1964 TREBLE - LOW OUTPUT
    By GREG HODY in forum Repair and Restoration
    Replies: 5
    Last Post: 10-23-2009, 07:44 PM
  5. No fuss, reasonably priced winder with most of the bells and whistles
    By SK66 in forum Tools and Coil Winding Gear
    Replies: 4
    Last Post: 03-19-2008, 08:54 PM

Tags for this Thread

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
  •