Quick dumbass impedance question - 8ohm and 4ohm cabs together?

[Clarky]

Is it possible to stack a 4ohm and an 8ohm cab and run from an amp that goes down to 2 ohms (like my Acoustic Image Clarus+)? Also, I presume it definitely wouldn't work with an amp that only goes to 4 ohms (eg, Markbass F1)?

I'm sure its in the Wiki somewhere but there are 127 replies on the impedance thread and life is too short ...!

[molan]

I think 4 ohms plus 8 ohms together is going to give you around 3 ohms combined.

[Clarky]

Thanks Barrie. I presume that means it might work with a 2ohm head but not a 4 ohm ... or do the little b*ggers only work in multiples of 2 ohm? lol. i really am an electronics numptie!

[icastle]

4Ω + 8Ω = 2.67Ω (in parallel).

So you can use that combination of cabs on your head that goes down to 2Ω, but not on the head that goes down to 4Ω.

[Gwilym]

[quote name='Clarky' timestamp='1328651649' post='1530811']
Is it possible to stack a 4ohm and an 8ohm cab and run from an amp that goes down to 2 ohms (like my Acoustic Image Clarus+)? Also, I presume it definitely wouldn't work with an amp that only goes to 4 ohms (eg, Markbass F1)?

I'm sure its in the Wiki somewhere but there are 127 replies on the impedance thread and life is too short ...!
[/quote]

you'll get a power mismatch as well, even if your amp does handle a 2.7ohm load, i.e. the 4ohm cab will be louder - assuming the cabs are the same sensitivity - which in this case I think they are?

[Clarky]

Hmmm good point about power mismatch. Think I'll give my scheme-y type scheme a miss! Thx gents

[Gwilym]

[quote name='Clarky' timestamp='1328655845' post='1530896']
Hmmm good point about power mismatch. Think I'll give my scheme-y type scheme a miss! Thx gents
[/quote]

but you'd get around the mismatch by using 1 amp per cab, and slaving one amp from the other, then you can match the individual cab volumes with the master volume of each amp.

[Clarky]

Trouble is I want a neat one-hand lift mini- rig rather than a team of roadies and electricians!!!

[chris_b]

What cabs?

A 4 ohm 212 and an 8 ohm 112 will give all speakers the same power so will not be a mismatch.

If you're putting a 4 ohm 112 and an 8 ohm 112 together they will receive different levels of power, but at your volume levels I doubt it would be too noticeable.
[font=Arial][size=2] [/size][/font]

[Clarky]

I have an 8 ohm 2x10 (Acme Low B2) and was considering pairing it with a second 2x10 Low B2 which is 4 ohm (the latter is FS on BassChat, hence thinking about it)

[chris_b]

Could you email Andy at Acme?

I would happily put 4 and 8 ohm cabs together if they were from the same line and same form factor. In my case I'm looking for an AE212 to put with my AE112.

I can't see that a 4 ohm 210 drawing 2/3rd and an 8 ohm 210 drawing 1/3rd of the power from the amp will be noticeably out of balance.

[Clarky]

I've dropped Acme an email and will let you know what they say

[Clarky]

[size=3][font=comic sans ms,cursive][font=Arial][font=Arial]Andy from Acme's reply:[/font][/font][/font]


[font=comic sans ms,cursive][font=Arial][font=Arial]Sorry- I don't have a good answer. If you connect the two cabs in parallel (daisy chained), the 4 ohm cab will receive 2/3 of the power, and the 8 ohm cab will receive 1/3 of the power. So, to use your word, it would be a mismatch.[/font][/font][/font]

[font=comic sans ms,cursive][font=Arial][font=Arial]The best way to use the two together would be to use a stereo power amp, use the amp's level controls to balance the two.[/font][/font][/font][/size]

Edited February 8, 2012 by Clarky

[KennysFord]

Nice one Clarky,
I was wondering the same. I asked a couple of weeks back about running a bi amp system as my cabs are mis matched at the moment.
The tumbleweed was very apparent.
You did better than I did bud.

[aldude]

[quote name='chris_b' timestamp='1328662824' post='1530981']
What cabs?

A 4 ohm 212 and an 8 ohm 112 will give all speakers the same power so will not be a mismatch.

If you're putting a 4 ohm 112 and an 8 ohm 112 together they will receive different levels of power, but at your volume levels I doubt it would be too noticeable.

[/quote]

This!!!

I use a Barefaced Compact (8 ohm) 1x15 and Super 12 (4 ohm) 2x12.

So, 2/3 of the power goes to the S12, but this is divided between the speakers. So, all three speakers get 1/3 of the power - I guess it's as if I used three 8 ohm cabs, 1x15, 1x12 and 1x12.

I don't see a mismatch here! And I certainly don't hear one.