How do I run a 16 ohm cab along with an 8 ohm cab?

Discussion in 'Cabinets & Speakers' started by Circle7, Nov 11, 2011.

  1. Marshallhead

    Marshallhead Well-Known Member

    Joined:
    Jun 3, 2009
    Messages:
    1,430
    Likes Received:
    606
    We're going round in circles on this one. Running amp 16 into speaker 16 at the same time as 8 into 8 is a mismatch, same as running the amp's 16 out into the 8 ohm cab on it's own and is not recommended, no matter whether it sounds better or worse.

    Only safe options are either to use a correctly matched single cab, or the 8ohm out to the 16 ohm cab alongside the 4 ohm out into the 8 ohm can.

    Or ignore all this and risk breaking the amp.
     
  2. Reckless_Life

    Reckless_Life Well-Known Member

    Joined:
    Nov 14, 2011
    Messages:
    734
    Likes Received:
    317
    If you want to combine the internal speakers with an external cab :

    1/ The amp is internally wired for 8 Ohms, so :
    Get a matching external cab that does 8 Ohms, so you can set the output selector of the amp to 4 Ohms.

    2/ Or, when keeping your external cab at 16 Ohms :
    replace the 2x 16 Ohm speakers in the amp with 2x 8 Ohm speakers, wire these in series to 16 Ohms. Put the output selector of the amp to 8 Ohms.

    3/ Or, disconnect one 16 Ohm speaker in the amp, so the other speaker gives you 16 Ohm.
    4/ Or, disconnect two 16 Ohm speakers in your 4x12 cab, and wire them parallel to 8 Ohm.
     
  3. Dmann

    Dmann Well-Known Member

    Joined:
    Dec 28, 2008
    Messages:
    2,021
    Likes Received:
    2,000
    Location:
    Calgary, Canada
    FYI - Santiago is the EET that designed the JVM, and if he says you can do it, then you can do it.

    I asked the same question When I got my JVM210H as I have an 1982 JCM800 Lead series with 4x12g-65's wired for 8 Ohms and a home made 4x12 thats wired for 16 Ohms.
     
  4. Reckless_Life

    Reckless_Life Well-Known Member

    Joined:
    Nov 14, 2011
    Messages:
    734
    Likes Received:
    317
    I wanted to ask if this was also the case for the 2203KK amp?

    But, what Santiago posted, it is not mentioned in the JVM handbook.

    In fact, in the handbook it says :
    "Any other speaker configurations may stress the power amplifier section and in extreme cases may lead to valve and/or output transformer failure."


    That's a far stretch from saying that "..everything will be perfectly matched and the power splitted equally..."
     
  5. Ken

    Ken Well-Known Member

    Joined:
    Feb 24, 2009
    Messages:
    9,944
    Likes Received:
    3,148
    Location:
    Arlington Heights, IL
    My opinion is that Marshall didn't want to get too technical with the unwashed masses by explaining how the JVM differs from most/all other Marshalls. After all, even here lots of people's posts show ignorance of matching so imagine your average musician. The engineers came up with a cool design for users, but Marshall's marketing department decided users as a whole are too stupid to not misinterpret the information and plug lots of cabs into other amps.

    Ken
     
  6. bolt22

    bolt22 New Member

    Joined:
    Apr 15, 2012
    Messages:
    108
    Likes Received:
    16
    Circle, you can bet on this: be putting some money away, you'll eventually need it for a new OT (and, when you least expect it!)

    Then, go call the Marshal experts (if you can locate them??)
     
  7. santiall

    santiall Well-Known Member

    Joined:
    Aug 12, 2010
    Messages:
    353
    Likes Received:
    833
    It says "MAY" not "WILL". The 16+8ohm configuration is a perfect match if connected to the right outputs as described elsewhere.

    Don't worry either about the output transformer myth, there is no problem with mismatching loads in any amps or splitting the load as long as there are available outputs, this is not any JVM exclusive feature, it is just plain physics. As long as there is a load connected properly you'll be safe, danger comes with intermittent connected loads, poor cabling, etc, but a mismatch by itself won't cause any harm
     
    Dmann and The Ozzk like this.
  8. GIBSON67

    GIBSON67 Well-Known Member

    Joined:
    Sep 8, 2008
    Messages:
    9,046
    Likes Received:
    4,971
    Location:
    Lakeland, TN
    Ask yourself "who will be paying for the repair work" and then run your amps anyway you want.

    I am going to always match my impedances with my Marshall! I've had to replace a power tube, the tube socket and a couple of diodes because of a mismatch...but oh I forgot this stuff never happens!
     
    Ray Baker likes this.
  9. Ken

    Ken Well-Known Member

    Joined:
    Feb 24, 2009
    Messages:
    9,944
    Likes Received:
    3,148
    Location:
    Arlington Heights, IL
    Well, Santiall is right actually, but the caveat is that not all Marshall amps can be run with the mismatched cabs in the various outputs. For example, many DSL's have been modded with the ground defeating the fail safe, and I would not plug a 16 ohm and 8 ohm cab in at the same time on this amp!

    I understand the JVM and 800 KK amps can accept the mismatches, but since so many people have a poor understanding of this, I think the safe rule of thumb is to just tell people to match the load to the amp.

    Ken
     
    GIBSON67 likes this.
  10. The Ozzk

    The Ozzk Well-Known Member

    Joined:
    Mar 28, 2011
    Messages:
    6,777
    Likes Received:
    7,070
    Location:
    Calgary, AB
    Speakers can also be plugged this way to the AFD.:wave:
     
  11. Luvverly Joobly

    Luvverly Joobly Active Member

    Joined:
    Apr 18, 2010
    Messages:
    388
    Likes Received:
    190
    Location:
    West Mids, U.K
    I am not 100% sure but I think either Weber or Radial made a box which would enable you do run 2 different rated cabs?
     
  12. sdrrock

    sdrrock New Member

    Joined:
    Apr 13, 2013
    Messages:
    14
    Likes Received:
    1
    Hi there i have a question i just need clearing up i know its sort of explained above but just need a solid answer.
    i have a 2203kk, a 16 ohm cab and an 8 ohm cab. am i right in understanding if i plug the 16 ohm cab into the 8 ohm socket and the 8 ohm cab into the 4 ohm socket my amp will be safe?

    thanks
     
  13. Soporific

    Soporific New Member

    Joined:
    Feb 6, 2018
    Messages:
    9
    Likes Received:
    3
    Yes it will be safe.

    But from reading this entire thread today trying to get to jvmforum it seems the biggest threat to your amplifier actually is the operator turning into a complete pussy if the certified goldenrod Marshall factory literature is followed to a T.
     
  14. soundboy57

    soundboy57 Well-Known Member

    Joined:
    Dec 27, 2009
    Messages:
    2,726
    Likes Received:
    2,313
    Location:
    Oregon
    Started in 2011, ended in 2014, but brought back so I could learn the word "goldenrod". Thank you!
     
  15. Filipe Soares

    Filipe Soares Well-Known Member

    Joined:
    Mar 8, 2019
    Messages:
    1,655
    Likes Received:
    2,874
    I actually have learned something new in this thread...

    I´m going to try mixing a V30 with a G12CV Neo in my 2203kk... I have both, one 16 and the other 8ohms and I think they will mix together very nicely.
     
    Mitchell Pearrow likes this.
  16. Exotic

    Exotic Well-Known Member

    Joined:
    Sep 3, 2018
    Messages:
    689
    Likes Received:
    636
    switch out the speakers and match the impedance ,keep the cabs
     
  17. RickyLee

    RickyLee Well-Known Member VIP Member

    Joined:
    May 22, 2010
    Messages:
    10,041
    Likes Received:
    3,466
    Location:
    Riverside CA U.S.A.
    I ended up trying this a few times, and it works out well. I could not hear any sound level differences running the 8 ohm cab into 4 ohm tap, together with 16 ohm cab into 8 ohm tap. It was an even sound level blend to my ears.
     
    SkyMonkey and ( . )( . ) like this.
  18. trax1139

    trax1139 Well-Known Member

    Joined:
    Apr 1, 2011
    Messages:
    152
    Likes Received:
    368
    Just plug and play...don’t worry about it. It’s a freakin speaker. Been playing 40+ years in rock bands of all calibers, ALWAYS used Marshall amps, never gave it a consideration and never had an issue. A direct short would be a problem, otherwise it’s just a freakin speaker.
     
  19. spacerocker

    spacerocker Well-Known Member

    Joined:
    Feb 6, 2009
    Messages:
    1,641
    Likes Received:
    1,177
    Location:
    UK
    It would be - be because (as has been pointed out many times) - the loads and impedances are matched this way....

    Yes, but a speaker is a load, and loads should be matched to the outputs.....having said that Santiago has said that the JVM is pretty tolerant to mis-matches, as long as there is a load of some sort attached.
     
  20. trax1139

    trax1139 Well-Known Member

    Joined:
    Apr 1, 2011
    Messages:
    152
    Likes Received:
    368
    Yes, but, what? You just double downed on what I said...plug and play. Don’t worry about it. A load is a load...a speaker is a speaker.
     

Share This Page