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2 ohm amp running multiple cabs?

Discussion in 'Amps and Cabs [BG]' started by grouse789, Feb 2, 2017.


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  1. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    Ok, my 1998 eden metro combo 210 puts out 2 ohms.
    The combo cabinet has two 4 ohm 10's built in. They plug into the amps backside in one of the three speaker outs.

    Can I safely daisy chain two 8 ohm cabs off one of the other speaker outs?

    Sorry but ohms confuse me at times. I'm certain one extension cab is fine, but not sure how the ohm load will change if adding another one.
    Thanks!
     
  2. If the amp is stable into 2Ω then it cannot go below that. Two 4Ω internal drivers are all the combo can manage. Chaining your two 8Ω cabinets will give you a 1.33Ω total load. Your amp will fail.

    What you could do is wire the combo’s drivers in series for 8Ω. Then you could add the other two 8Ω cabinets for a total load of 2.67Ω which the amp will have no problem with. The combo will not be significantly quieter run at 8Ω by itself.
     
    Last edited: Feb 2, 2017
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  3. Mystic Michael

    Mystic Michael Hip No Ties

    Apr 1, 2004
    New York, NY
    No. The amp in your Eden Metro can handle an impedance of 2 ohms. Impedance is a measure of electrical resistance - not a measure of some sort of output.

    What you want to know is what is the impedance of the entire cab? If your two 10s really do have an impedance of 4 ohms each, then they're either wired in parallel (standard) for a total impedance of 2 ohms (highly unlikely), or wired in series for a total impedance of 8 ohms.

    You can do so safely only if the existing impedance is 4 ohms or more - something that would be impossible if your two 10-inch woofers are rated at 4 ohms each, and wired in parallel for a total impedance of 2 ohms.

    MM
     
    Last edited: Feb 2, 2017
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  4. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Find your manual here:
    Historical Products | EDEN Amplification
     
  5. Mystic Michael

    Mystic Michael Hip No Ties

    Apr 1, 2004
    New York, NY
    I once owned an Eden Nemesis combo amp - the NC210. It was the only cab I've ever experienced with its woofers wired in series. Of course, the series wiring cut down on the total amount of output available from the amp, but Nemesis compensated for that by using a pair of 10s that were highly sensitive. So it worked out fine.

    MM
     
  6. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    Thanks for the link.

    It says on the chart "when speakers wired in parallel, load increases shown below.

    Two 8 ohm cabs and one 4 ohm = 2 ohms

    That's from the manual, sound correct?
     
    HolmeBass likes this.
  7. jlepre

    jlepre Supporting Member

    Nov 12, 2007
    Cedar Knolls, NJ
    So that's why you wanted my 15... ;)
     
  8. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Which manual are you viewing? Are you certain your amp is a "1998 Metro?"
     
  9. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    Hi Jay no that's not the reason I just figured since I had them let me see what it would sound like with three cabinets linked up.

    Yes I am sure it is a 1998 I am the original owner. However the PDF online was for a 2006 metro. And as far as I have heard the metros only came equipped with four on the speakers on special order. So I am not sure if what I read is true or if they base that off of 2 8ohm speakers
     
  10. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    I think I should have left brand specifics out of this question
    And rephrased it simply as an equation of
    2 ohm amplifier with three outs running into three cabinets
    One being a 4 ohm cabinet
    +2 additional 8 ohm cabinets
     
  11. That would equal 2Ω and be safe.
     
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  12. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    That's what I'm guessing if I treat the 4 ohm cab as two 8 ohm cabs
    Thanks guys
     
  13. Rip Van Dan

    Rip Van Dan Supporting Member

    Feb 2, 2009
    Duvall, WA
    This combo was originally an 8 ohm combo using the internal speakers. If you physically looked at the back of the speakers in your metro and they say they are marked 4 ohm, then your metro is wired in serial and it is an 8 ohm cabinet as-is. In that case, the answer to your question is YES.

    You can actually hook up to three additional 8 ohm cabs to it (four 8 ohm cabs=2 ohm load) and there are three 1/4" outputs in the back to do that or you can daisy chain them. All connections on this combo are parallel so the amp sees the same thing regardless if you plug them all into the back or daisy chain them.

    By itself it will put out 240-watts to its internal speakers. Hooking up one more 8 ohm cab will give you a 4 ohm load (400 watts on your year's model) and both cabs will get a maximum of 200-watts each. If you hook up two 8 ohm extension cabs, that will give you a 2.67 ohm load and produce about 500 to 550-watts. You can also hook up a 4 ohm cab if you like (instead of two 8 ohm cabs) and that will also give you that same 2.67 ohm load. The Eden Metro can run load that all day without any problems and you can safely even run three 8 ohm cabs added to it if you like.

    Keep in mind that if you add a 4 ohm cab, the 4 ohm cab will get twice as much power as the 8 ohm on-board speakers. If you hook up a 4 ohm 410 cab to your metro, all the speakers will get equal amounts of power and it will be very loud. If you hook up a 4 ohm 210 cab, then the speakers in the 4 ohm 210 will get twice as much power as the on-board speakers and you'll want to pay attention to the sound from those speakers to make sure you are not stressing the 4 ohm cab's speakers.

    To give you a little perspective on volume of this combo, a friend of mine used his along with a single Eden D112XLT hooked up as an extension speaker and it more than covered the 500-person club where he was playing in when I was there. It's a nice and easily expandable combo. Only downside is it is heavy.

    One other thing you might not be aware of is that some of the Metros have a "speaker on/off" switch. Not sure if you 1998 model came with that. If it did, that switch ONLY turns off the internal speakers and does not turn off any extension speakers you are using.
     
    Last edited: Feb 8, 2017
    HolmeBass likes this.
  14. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    Wow thanks Rip! Very informative. I figured out the speaker on/off switch a while back.(yes I have it).
    And yes it is a very loud cabinet, I used to run it with a 410, and it would just blow wind in a good way.
    My tweeter either died or more likely I goofed up the wiring in it a while back. So I have the tweeter disconnected, and the wires running I'm guessing parallel . Positive running to one cone to the next with the negative running back. So I think it would now be 4 ohm?
     
  15. This covers it! I don't think Eden ever released a 4 Ohm metro. The D210XLT's used in the combo were all 8 Ohm.

    So this is the first place TB let you down. Op clearly posted 4 ohm speakers/drivers, not combo, and two long-time posters missed that and chimed in right away with mis-information! For shame.

    But OP learn to always consider the cabinets nominal impedance. Unless you need to change a driver, don't worry about their impedance.

    I used to gig my Metro with a D112XLT and I know Rip saw me play in Roanoke once, is that what you were relating?

    I also ran the Metro with a 4 ohm Genz Benz UB212T cabinet for outdoor festival gigs and that was a great sounding pairing.

    I once added the D112XLT and the Genz and ran at 2 Ohms. That was amazing. All those speakers, all that power, it really sounded great. The Genz lacked just enough efficiency to pair really well with the Eden cabs, the extra power it drew balanced by the slightly lower efficiency.

    On the downside of mixed driver pairings, I ran the Metro with a SWR BigBen 118 and that box was so lacking in efficiency that I could only hear it at all on my low F and E. I suppose if I played a 5er it might have been a bit better.

    And then once I paired it with an Ampeg 115 and the D112. That combination was so bad that I was panicking at an outdoor gig. I actually unplugged the Ampeg and just used it as a stand and my sound dramatically improved immediately.

    Which is to say, definitely try out the combination you intend to use and turn it up to gig volume, then move around the room to listen if the cabinets actually work together.
     
    Rip Van Dan likes this.
  16. SanDiegoHarry

    SanDiegoHarry Banned Supporting Member

    Aug 11, 2008
    San Diego, CA
    it would not make sense to make combo that is already running a 2ohm load and then have a speaker out. Me, I'd put a meter on the existing speakers to get an idea of what the current load is before plugging other stuff in... I'd guess it's 8 or 4 ohms, not 2 ohms. That would make it safe to attach external cabs - but if it's running a 2 ohm load NOW, nothing in the world you could attach would be safe.
     
    Last edited: Feb 3, 2017
    HolmeBass likes this.
  17. The best way to think about the impedance (Ohms) rating of an amp is to say.
    The amp is capable of driving a 4 Ohm load.
    The load being the speakers.
    4 Ohms is just an example.
    It could be 8 or 2 or even 16 Ohms.

    The amp doesn't put out Ohms.
    The speakers present a certain impedance, expressed in Ohms, to the amp.
    If your amp is capable of driving a 4 Ohm minimum load, then that is telling you that the total combination of speakers should go no lower than 4 Ohms.
     
  18. Your first post said you had two 4 ohm 10s, now you're wondering if the whole cab is 4 ohms.

    You can't get a 4 ohm cab from two 4 ohm speakers no matter how you wire them.

    Also your description of the wiring is confusing.

    We want to help, but you need to be more accurate in your descriptions.

    Do you have a multi-meter? Because you can measure the DC resistance of your cabinet with one and that will let you know the nominal impedance of the entire cabinet - which is what you want to know to see how it will combine in parallel with the other cabinets.

    Unplug the internal cab's jack from the speaker output. Put one probe from the MM on the tip, the other on the sleeve. Set the MM to read resistance - Ohms - possibly indicated by the capital Greek letter Omega.

    The DC resistance will be below the nominal impedance. So if DC resistance is less than 8 ohms but bigger than 4, it's an 8 ohm nominal impedance.

    If it measures less than 4 but more than 2 ohms it's a 4 ohm cab. Less than 2 and it's a 2 ohm cab.

    Messing around with the wiring inside the cab is not a good idea for someone who doesn't understand Ohm's law and how impedances combine in parallel or series.

    Parallel wiring: one prong of the input jack is connected to the same terminals on both speakers. The other prong is connected to the other terminals on both speakers.

    Series: one prong of the jack is wired to one terminal on a speaker, say the positive. Then the negative terminal on that same speaker is wired to the positive terminal of the other speaker. Then the second speaker's negative terminal is wired to the other prong on the jack.

    In your case, the jack is the speaker cable that plugs into the amp's output, since the internal cab has no jack.
     
  19. Munjibunga

    Munjibunga Retired Member

    May 6, 2000
    San Diego (when not at Groom Lake)
    Independent Contractor to Bass San Diego
    The two internal 4-ohm drivers are probably wired in series for an 8-ohm load. Putting two 8-ohm cabs in parallel is a 4-ohm load which, when combined with the internal 8-ohm load, would result in a 2.7-ohm total load. Safe, but not much power going to each speaker.
     
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  20. grouse789

    grouse789 Supporting Member

    Jun 13, 2004
    Westchester NY
    Sorry for the confusion guys. Like I said in my first post, I find the ohm issue confusing.
    The cones inside he metro are stamped with 4 ohms on each one.
    The amp itself is rated down to 2 ohms.

    Funny thing is I've ran it with two extra cabs years back without thinking about it. Worked fine, but recently I dug it out of storage and knowing a tiny bit more than back then I just wanted to find out if that was ok or not.
    Lol
    Thanks
     

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