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adding a 2nd cab question

Discussion in 'Amps and Cabs [BG]' started by PATTY1, May 4, 2010.


  1. PATTY1

    PATTY1 Guest

    Dec 28, 2009
    i have a SWR400 bass amp driving a peavey 410 8ohm cabinet, can i add a 210 cabinet and what ohm rating should it be ???
     
  2. If your minimum ohm load is 4 ohms on the head,you want another 8 ohm cab.
     
  3. Straight from Peavey:

     
  4. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    If you add 2 further 10 inch loudspeakers with an impedance of 16 ohms
    each wired in parallel to make an 8 ohm cab.
    Four of your 10" speakers will be getting precisely half the power of the other two.
    Therefore limiting the overall power of your rig to the exact point of fart out of a 2 X 10 cab + whatever coupling effect you get from the under driven 4 X 10.
    Now lets look at the only other possibility here 2 x 10 inch 4 ohm speakers wired in series.
    Same problem each 10" loudspeaker on the two by ten still gets twice the power that any of the other 10's get.
    So what is the impedance of a 6 x 10 I hear you ask, well usually
    its arranged series parallel like your peavey but obviously with 2 sets of 3 X 8 ohm speakers in parallel wired one set in series with the other, total 5.3 ohms.
    So if you add a pair of speaker sockets each wired in parallel to your peavey cabs 2 parallel circuits and output these to a tweeterless 4 ohm 2x10 which is rewired one speaker to each socket.
    You have 5.3 ohms and a balanced load to each 10":D
     
  5. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    There is more to this than simple mathematical division.:meh:
     
  6. James Judson

    James Judson

    Jul 16, 2009
    Basmec has some fuzzy math there. Bottom line is: Any combination of speakers that add up to 4 ohms will work.

    What he got right is if you have two cabinets of 8 ohms plugged into your head you will have an 4 ohm load. Your amp will like that with possibly no problem. If there is a problem it may come from the cabinets sharing the watts. The 2 tens will be working harder than the 4 tens. If all the speakers are the same you will have 2 speakers that are driving twice as hard as the other 4.

    Look at the watts rating. Will the 210 cab take the same watts as the 410? If yes then your set.

    If you have the cabinets already go ahead and try it. If you don't have the cabinets I would go for another 410 so you will have more of the same only louder.

    With that all said musicians use mismatched speakers all the time. Sometimes without knowing cuz the speakers are inside the same cabinet.

    Heres what you need to remember. Matching ohms saves your amp. Matching watts saves you speakers. There is actually a bit of wiggle room here.

    Good luck
     
  7. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    There is nothing Fuzzy about my maths and a loudspeakers thermal rating has nothing to do with balance unless in doubling the thermal wattage rating of the speaker you also reduce its efficiency by 3dB.
    A balance of power split evenly between similar loudspeakers is the
    only intelligent way forward.
    PS This quote almost right "With that all said musicians use mismatched speakers all the time. Sometimes without knowing cuz the speakers are inside the same cabinet".
    It should have read moron, not musician.:meh:
     
  8. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Yes, and for equal power distribution it should be 16 ohms.
     
  9. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    play nice kids.

    good luck finding a 16 ohm 210. i have used 8 ohm 410 and 210 cabs on the same rig with good results. However, the 210 was rated for a lot more watts than it was getting and had pretty high excursion. Yes, each individual driver in the 210 will get twice the wattage as each driver in the 410, but the net effect may be that the cabinets sound about as loud as one another (maybe).

    best advice? bring your rig to the store and try it with the 210 cabs you're thinking of.
     
  10. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Well Bill! If he does the added socket pair thing he can use the 2 X 10 with a pair of speaker cables stand alone for a practice or small gig.
    Assuming its safe at 400 watts!.
    What does the amp put out at 16 ohms for a possible stand alone 2 X 10 option?:meh:
     
  11. IvanMike

    IvanMike Player Characters fear me... Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    that's some serious rewiring and probably would involve switches. I say don't reinvent the wheel. try the "see how they sound" option 1st.

    my guess is 160 watts @ 16, maybe less. you don't want a 16 ohm cab, those are for guitar players...:p
     
  12. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    Yup! Well once he has finished auditioning 4 ohm 2 X 10's he can just rewire the one he chooses in series. Also thinking about cabs with a tweeter, knowing that there are no inductive components in the crossover design in circuit with the bass drivers is a must.
    Very few bass cabs have a low pass filters anyway, Good job!.
    I still like my funky added sockets ploy best though.
    But that takes wiring the high pass filter to the sleeve of one speaker
    socket in the 2 x 10 and the tip from the other if you separate the speakers to sockets. Not hard to do and makes it a very adaptable
    system.:D
     
  13. Bassmec

    Bassmec

    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    "We don't need no stinking switches!".
    Just an added pair of speakon sockets in the back of the 4 X 10 cab will do. Its nothing like complicated.:D
     

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