Mixing cabs of different impedance?

[spiltmilk_2000]

Hi There, I have a question about the above which Im hoping someone might be able to assist with.

I currently have an Aguilar DB750 with GS115 and GS410 cabs (both 4 ohms) but am considering purchasing a lightweight rig for small gigs (Aguilar TH500 and SL112)

My question is will I be able to combine the 8ohm 112 cab with one of the 4ohm GS cabs if required? Say I wanted to use either the TH500 or the DB750 head with the GS115 AND the SL112 would there be any mismatching problems due to different impedance ratings? I have no idea how these things work.

Many thanks in advance for any help or advice.

[LewisK1975]

If you link an 8 ohm cab and a 4 ohm cab in parallel (the normal way) you'll get an impedance of 2.66666 ohms. That'll be ok for the DB750 as it can work down to 2 ohms. The TH500 only works with a min impedance of 4 ohms, so you couldn't use it with that mix of cabs..

You could get them to work together by linking the cabs with series cable which will add the impedance together and give you a 12 ohm impedance at the amp. But by doing this you'll find you need to turn the amp up further than normal to achieve your usual volume.

Hope this helps.

[alexclaber]

[quote name='LewisK1975' timestamp='1435322223' post='2807676']
If you link an 8 ohm cab and a 4 ohm cab in parallel (the normal way) you'll get an impedance of 2.66666 ohms. That'll be ok for the DB750 as it can work down to 2 ohms. The TH500 only works with a min impedance of 4 ohms, so you couldn't use it with that mix of cabs..[/quote]

Correct!

[quote name='LewisK1975' timestamp='1435322223' post='2807676']You could get them to work together by linking the cabs with series cable which will add the impedance together and give you a 12 ohm impedance at the amp. But by doing this you'll find you need to turn the amp up further than normal to achieve your usual volume.
[/quote]

Although you can do this in theory it's a bad idea in practice with non-identical cabs because they'll interact in strange ways due to their differing impedance curves - imagine getting a 12 band graphic EQ and pushing the sliders about randomly and hoping it'll sound good. That kind of bad idea!

[LewisK1975]

[quote name='alexclaber' timestamp='1435322531' post='2807682']
Correct!



Although you can do this in theory it's a bad idea in practice with non-identical cabs because they'll interact in strange ways due to their differing impedance curves - imagine getting a 12 band graphic EQ and pushing the sliders about randomly and hoping it'll sound good. That kind of bad idea!
[/quote]

Thanks Alex for chipping in with proper technical advice on this!

Edited June 26, 2015 by LewisK1975

[chris_b]

Are you sure the GS115 is 4 ohm? The Aguilar website says they are 8 ohm.

I've use 2 112 cabs and now a 212 for years. With "modern" well designed cabs I'm not convinced there is a place for old style 115's any more.

I'd get 2 SL112's if you were after a flexible small rig.

[spiltmilk_2000]

Thanks for the advice guys... Maybe buying two 112s is the answer so I have more flexibility from a small, medium and large rig. Although this won't please the wife from a finance or storage point of view :-)

[JTUK]

Check out the Baers here as a 2x112 option... you could run them with either a TH500 or the DB750.

[Musashimonkey]

[quote name='JTUK' timestamp='1435343197' post='2807991']
Check out the Baers here as a 2x112 option... you could run them with either a TH500 or the DB750.
[/quote]
Mmmmm, sounds good to me! ☺️