Tube amp ohm load question

Discussion in 'Amps and Cabs [BG]' started by Natasdrol, Jun 10, 2019.

  1. Natasdrol

    Natasdrol Supporting Member

    Dec 17, 2017
    Rancho Cucamonga ,CA
    I did a search for this and each thread has different answers, and most deal with 2.67ohm loads.
    Here's my question.
    I have a barefaced 410 8ohm cab, recently got a barefaced 210s, switchable between 12 ohms and 4 ohms. Going to run it at 12 ohms with the 410s 8ohms, making a 4.8 ohm load.
    I use tube amps. Currently have a Reeves 225 with 8, 4 and 2 ohm option.
    Was going to daisy the 2 cabs together.
    Is running the 4.8ohm safe and if so which tap?
    Thx for any advice in advance.
  2. Wasnex


    Dec 25, 2011

    The best advice is to contact Reeves. 4.8 is really close to 4 ohms, so I will be surprised if they so no, but better safe than sorry.

    4 and 12 ohms is very odd. Any idea how they achieve this. Normally you would expect 4 or 16 ohms. This would be achieved with 8 ohm drivers in parallel or series.
    Last edited: Jun 11, 2019
    BassmanPaul likes this.
  3. basscooker

    basscooker Commercial User

    Apr 11, 2010
    Northern KY
    Cab fan, hobbyist
    4 and 12? Please elaborate.
  4. That is weird. I wonder how they achieve it.

    basscooker likes this.
  5. Gotta be 16/4 not 12. I talked to Bill Jansen this week about adding a 8 ohm tweeter (Klipsch Center Chanel) box to a 4 ohm 2-15. He said it won't hurt the amp and try the 2 and 4 ohm setting to see which sounds better. I think the 4 ohm tap works better. (louder). Because the smaller tweeter box has a higher resistance, they even out pretty well.
    Last edited: Jun 10, 2019
  6. Wasnex


    Dec 25, 2011
    I doubt the OP knows how 4 and 12 ohms is achieved. It's straight from the website. Barefaced Bass - Two 10S

    Could be a typo.
  7. Barefaced use their own 'best nominal impedance strategy' for safely loading a SS amp using standard impedance maths.

    In contrast with how TC does it. TC cabs are '8 ohm' but you can use three in parallel with a 4 ohm TC amp.
  8. Tim1


    Sep 9, 2005
    New Zealand
    I have both these cabs, Barefaced Four 10 (8 ohms) and the Two 10s. I set the Two 10s to 12 ohms and have run the combination with several all tube heads at 4 ohms without any issues. This is the setting that Alex Claber recommended and he knows his stuff. Plenty of discussion about this on the Barefaced thread.
    Rockbobmel likes this.
  9. MmmmmKayyy
  10. Nighttrain1127

    Nighttrain1127 Supporting Member

    Nov 27, 2004
    Near Worcester MA
    I thought the general consensus on tube amps was if it is over 4.8 ohms then use the next tap up . If I remember correctly someone was going to run a 2.67 ohm load and was going to use the 2 ohm tap and several of the amp experts told them if it is over to move up to the next tap in that case 4. But the suggestion to contact the manufacturer in this case is the wisest .
    Rockbobmel likes this.
  11. Mushroo

    Mushroo Guest

    Apr 2, 2007
    Barefaced 410 + 210 is nominal 4 ohms (electronically equivalent to their 4 ohm 610 cab) and you should use the 4 ohm tap.

    Think of it this way: Take a 4 ohm 610 cabinet. You can physically split it into 410+210 or 310+310 or 210+210+210 or even 6x110. So long as you wire it all correctly (mixing series and parallel harness) your amp doesn't "know" you've split the cabinet into multiple boxes. The amp still "sees" a 4 ohm 610 load.

    Last edited: Jun 11, 2019
    Bluzeman90 likes this.
  12. BassmanPaul

    BassmanPaul Inactive

    I would use the 4Ω tap as tube amps prefer to work into a lower load that the stated tap.
    Tim1 likes this.
  13. Wasnex


    Dec 25, 2011
    IMHO, the general consensus among informed people is to contact the amp maker because it depends upon how the amp is set up...Setup relates to factors like transformer turns ratio and plate voltage, which determines impedance loading of the output tubes.

    Although it is often true that tube amps are safer when the load is lower than the amp expects, Mesa's recommended safe impedance mismatch is on the high side. So with a Mesa amp, you would likely set the output impedance below the actual load rather than above it.
    Last edited: Jun 11, 2019
  14. Tim1


    Sep 9, 2005
    New Zealand
    General consensus is next tap down with tube heads, the reverse of solid state. Check with the manufacturer is good advice as you state. As I said, I have used this exact speaker combination with a variety of all tube heads at 4 ohms as recommended by Barefaced and have experienced no issues at all. Alex Claber knows his stuff and has discussed this point in detail on the Barefaced thread. To the OP: great speaker combination BTW
    Mushroo likes this.