Using 8 ohms and 16 ohm speakers mismatched

What's Hot
kelpbedskelpbeds Frets: 181
I have a plexi which is switchable between 4 8 and 16 ohms which I was running into a marshall 1922 cab rates at 8 ohms ( 2 x 16ohm speakers in parallel) - no problem.
I then bought another cab and want to change the speakers, but I accidentally bought speakers rated at 8ohms. 
So the new cab would be wired in parallel and give me 4ohms. 
No prob using the cabs separately - i just switch between 4 and 8 ohms on the amp.
However if I use both cabs together I've got one cab at 4 ohms and one at 8 ohms - running in parallel gives me 6 ohms. Is this ok to mismatch and should I set the amp at 4 or 8 ohms?
Or is there any other solution to this problem? 
thanks
Check out my Blues lessons channel at:  https://www.youtube.com/channel/UCBTSHf5NqVQDz0LzW2PC1Lw
0reaction image LOL 0reaction image Wow! 0reaction image Wisdom

Comments

  • ICBMICBM Frets: 71956
    Running an 8 and a 4-ohm cab in parallel actually gives you 2.66 ohms, but is safe with the amp set to 4 ohms. 2/3 of the power will go to the 4-ohm cab, which depending on what the speakers are may be a good thing or a bad thing.

    You would probably be better to wire the new cab with the speakers in series to give 16 ohms, which then gives a total impedance of 5.33 ohms when used with the 8-ohm cab, and is safe with the amp at either 4 ohms or 8 ohms, but better at 4 with a Marshall. In this case 2/3 of the power will go to the 8-ohm cab.

    What speakers are they? Does the 1922 still have the stock G12T-75s?

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

    0reaction image LOL 0reaction image Wow! 0reaction image Wisdom
  • kelpbedskelpbeds Frets: 181
    Apologies for my incorrect equations! Thanks

    The first 1922 is running two V30s of 16 ohms each (I changed the g12t-75s)

    The 8 ohm speakers are are G1265s. I would rather the bulk of the power went to them really as trying to get away from the harshness of the v30s a bit.

    Cheers!
    Check out my Blues lessons channel at:  https://www.youtube.com/channel/UCBTSHf5NqVQDz0LzW2PC1Lw
    0reaction image LOL 0reaction image Wow! 0reaction image Wisdom
  • ICBMICBM Frets: 71956
    kelpbeds said:

    The first 1922 is running two V30s of 16 ohms each (I changed the g12t-75s)

    The 8 ohm speakers are are G1265s. I would rather the bulk of the power went to them really as trying to get away from the harshness of the v30s a bit.
    Yes - that will also even up the sensitivity difference and stop the V30s sounding much louder, which they would if you made the G12-65 cab 16 ohms. Wire them in parallel and set the amp at 4 ohms.

    Unless you really crank the amp into power-stage distortion, impedance matching is not that critical anyway - and also contrary to popular belief, it's actually safer for valve amps to run into a too-*low* impedance load than too high, if you can't match it. (Although the opposite is true for solid-state, which is where this probably comes from.)

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

    0reaction image LOL 0reaction image Wow! 1reaction image Wisdom
  • kelpbedskelpbeds Frets: 181
    Just tried all that with the G1265s at 4 ohms in parallel along with the v30s. Sounds sweet! The v30s cut through quite a lot anyway so I think they work well at 1/3 power.
    Thanks!
    Check out my Blues lessons channel at:  https://www.youtube.com/channel/UCBTSHf5NqVQDz0LzW2PC1Lw
    0reaction image LOL 0reaction image Wow! 0reaction image Wisdom
Sign In or Register to comment.