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4 ohm cab + 8 ohm cab -> Orange AD200 head

Discussion in 'Amps and Cabs [BG]' started by Vismund_Cygnus, Apr 8, 2018.


  1. Vismund_Cygnus

    Vismund_Cygnus

    Apr 8, 2018
    Hello, I've got Orange AD200 tube head, Orange OBC115 8 ohm cab and Acoustic Control Corp 4 ohm cab. It's very important for me to find the way to correctly plug them both into this amp (I allow any technical modifications) because working together they reach my expectations. And I know nothing about electronics more than how to use tube amp, how to play it and generally what it is.
    My head's outputs:
    -4 ohm
    -4 ohm
    -8 ohm
    -Slave out
    Thanx in advance for any help :)
     
  2. Your cabinets will equate to a 2.67Ω load. Certainly not an ideal match up for your amp. I would recommend that you run one or the other but not both.
     
  3. Wasnex

    Wasnex

    Dec 25, 2011
    The Orange AD200B speaker outputs are not intuitive. The amp has two transformer taps, an 8 ohm tap, and a 4 ohm tap.

    Here are the factory approved options. 1. Connect one 8 speaker to the 8 ohm output (8 ohm load). 2. Connect one 8 ohm speaker to each 4 ohm output (4 ohm load). 3. Connect one 4 ohm speaker to either 4 ohm output (4 ohm load). See page 8 of the attached owner's manual.

    The amp is not rated 2.67 ohms, so this is done at your risk.
     

    Attached Files:

    LeftyD likes this.
  4. Could you elaborate a bit further on your comment that they meet your expectations?
    How have you determined this?
    Do you mean each one individually or both together?
    Thanks.
     
  5. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    That would be good advice if it was an SS amp, but it isn't. OP, plug them both into the 4 ohm taps. The chances of a 2.67 ohm load bothering a 4 ohm tap isn't even slight.
     
  6. Wasnex

    Wasnex

    Dec 25, 2011

    A 2:1 or 1:2 impedance mismatch is often safe with a tube amp, but some amps are set up to work better/be safer if the mismatch is on the high side; while others work better if the mismatch is on the low side. To my knowledge 2.67 ohms is not an Orange factory approved loading and I don't know how the AD200B loads it's output tubes. Unless your advice is based upon a specific understanding of how the AD200B is set up, perhaps the OP would be wise to consult with Orange Technical Support.
     
    P-oddz, Aqualung60, RickyWoo and 2 others like this.
  7. ac100X

    ac100X

    Apr 6, 2003
    California
    I have the same problem, I have a 66 fender bassman (my amp from high school days) and I want to pull it out of storage and use it for small gigs. The speaker cabinet is 2 x12 (4 ohms) the head has an external speaker out - but to what kind of speaker? I wanted to get a fender showman single 15 (8 hms) because the 2 x12's don't provide enough bass, but this would put me at 2.67 ohms and the head is 4 ohms. I was told not to go lower that 4 ohms, higher is ok but a higher miss-match put cuts power and at 50 watts I can't afford to loose much. I want to use the head & speaker cab together and not just the showman cab. Don't say dis-connect one of the 12's to get a 8 ohm load. I think I'm stuck unless I run two amps each with their own spealer. Any advice?

    PS: I also have an Orange 200AD and a Orange Tiny Terror Bass 1,000, 1977 Gallen Kruger 400B, VOX 125 head, SWR 200 watt.
     
  8. Wasnex

    Wasnex

    Dec 25, 2011
    Anytime you run an impedance mismatch on a tube amp your going to loose power and it's going to be harder on the tubes and output transformer. I believe most vintage Fenders are assumed safe with 1:2 or 2:1 mismatch as most have pretty stout output transformers. As long as you stay within this range, most likely the amp will operate fine, but you will wear the tubes out faster. I personally would feel more comfortable running a Fender into a lower than expected impedance, rather than a higher than expected impedance. Given most vintage Fender tube amps include a jack for an external speaker I believe Leo intended for them to be used with either the expected impedance (in this case 4 ohms) or 1/2 the expected impedance (2 ohms). I believe Fender Tech Support agrees with this position. Here's a thread where someone called Fender--read the first post to see what Fender said: https://www.thegearpage.net/board/i...-mismatch-which-is-near-unbelievable.1204610/


    A couple of things to consider: 1. If you have to drive the amp to max power to meet minimal volume requirement you are already putting additional stress on the tubes and output transformer. Running an impedance mismatch is just going to push the amp closer to the edge if anything is marginal. 2. It's likely the amp will sound best when driving the correct 4 ohm load. I have run a blackface Twin Reverb at 2 ohms and I thought it sounded much better driving a proper 4 ohm load.

    Maybe you could try the Bassman with a pair of Ampeg 210AVs? Or how about a 4 ohm Greenboy Bassic 15 with Fender cosmetics. Or perhaps just upgrade the 12s in your Bassman cab.

    Or maybe use the Bassman as a practice amp and gig the AD200B, which IMHO sounds a lot like a Dual Showman on steroids if you run the MV wide open.
     
  9. Vismund_Cygnus

    Vismund_Cygnus

    Apr 8, 2018
    OBC115 itself has a lot of deep low end and massive mids, but has no treble at all. Acoustic on the other side has weak lows, but sellective highs and stylish classic prog-rock like dry tone (its 40 years old cab). Each cab sound nice on its own, but i chcecked them together in several ways and it kicks ass, because they fullfill each other.
     
  10. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    The 66 Bassman was made to be used with a pair of 4 ohm cabs, but legions of Fender owners have been known to run them at 1 ohm for years, no problem.
    You must have been told that by someone who doesn't know that applies to SS. Tubes are the opposite. You can damage tube amps with too high an impedance load, not too low. Also, you don't get any lows from a 2x12 Bassman cab because it's sealed, not because it's a 2x12.
     
  11. Don't necessarily apply the conventions for a solid state amp, to a tube amp.
    Nice. It doesn't always work out that way.
    So were you checking them using a different amp or did you risk your's in the name of science?
     
  12. Vismund_Cygnus

    Vismund_Cygnus

    Apr 8, 2018
    I checked on two transistor amplifiers, but I risked in the name of science too :) Nothing burnt... yet. After this Acoustic cant handle this music (something around proggy stoner) on its own for me, Its just not deep enough, but OBC115 is on the other hand a lot to soft on its own. Btw it can't make hell on fuzz for example. I love them both so much that I dont want to search don't know where for "ultimate" cab. I dont like OBC410, which I'm selling now
     
  13. Nice that you found something that sounds good. Hope you can get the other thing solved as well.
    15"-ers just seem right for bass. Not that I subscribe to the old school bigger is lower, because a lot has to do with the cab.
    But my silly ass rule of thumb is that any speaker with a diameter smaller than the width across a bass just causes unwanted harmonic reflections throughout the universe. :D
     
    Novarocker and ak56 like this.
  14. edencab

    edencab

    Aug 14, 2013
    Toronto, On
    I wouldn't do anything other than the Owner's manual directions....unless I heard different from @agedhorse

    .....IMHO ....YMMV at your own risk
     
    Last edited: Apr 9, 2018
  15. Sorry Rick but I disagree. The Orange is pushing it’s output tubes basically at their limits. Adding a severe impedance mismatch could well push them too far especially with a bass.

    As for the Bassman 50 it was designed to run a single 4Ω load with it’s twin twelve Bassman cabinet. The fact that people abuse that minimum should not be used as an indicator that it’s alright to do so.
     
    P-oddz likes this.
  16. BTW I was remiss in not welcoming @Vismund_Cygnus to our ranks. I do so now! :D
     
  17. Vismund_Cygnus

    Vismund_Cygnus

    Apr 8, 2018
    Hello :) And thanx for advices from You all
     
  18. Rick James

    Rick James

    Feb 24, 2007
    New Jersey
    Here again you're using SS concerns that don't really apply to tubes. The output tubes aren't operating into a severe impedance mismatch, because the impedance they're operating into is the output transformer primary. Besides, even where the secondary is concerned 2.7 ohms versus 4 ohms is hardly severe, and that doesn't even consider the actual impedance of a speaker, which is anything but a constant.

    If that was the case it wouldn't have had an extension speaker jack. When you look at an SS amp that says 4 ohms next to the jack that doesn't mean you can only run a 4 ohm load, it means you should not run less than a 4 ohm load. When a tube amp says 4 ohms next to the jack that doesn't mean it has to be a 4 ohm load, that means you should not run more than a 4 ohm load.
     
  19. Rick, when I talk tubes, SS concerns are nowhere in my mind. Yes tubes handle lower impedance loads better than SS amps do but your statements are more than a little simplistic. A tube amp works at it’s best when the OPT has balanced impedances connected to it. In order for the primary impedance to match up with what the plates need it has to see the correct load on the secondary reflected back into the primary.
     
  20. Yeah! Me too too. What BPaul said.
    It's always nice to make the lumber feel at home.
    Welcome a board.
    :roflmao:
     

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