Mixing closed/open back cabs question

badgergman

badgergman

Member
Hello all.

Following a blown speaker a while ago, and to add more spread to the sound at larger gigs I invested in a Custom Audio Amplifiers 1 x 12 cab (closed back, Eminence Governor)) to match up with my Einstein combo (G12K-100 open back) (also as a "safety" measure and I suppose because it was a bargain on Ebay).

I have played the pair in tandem for a good number of gig hours now and I am noticing a odd response.

When the combo is used on its own it seems more alive, responsive to harmonic feedback, tighter sound perhaps....

When used with the ext cab the feedback response is not as immediate. Undoubtedly the sound is enormous with the additional speaker, and I can spread it to different areas of the stage/room by orientation, but is there something happening here that is causing the lack of feedback response?

Is it possibly down to mixing closed back and open back cabs?

Any insights, similar experiences most welcome.

Its not that I am getting a bad sound with ext cab, its great but something seems to be happening that I don't understand....

Thanks
 
What do you exactly mean by "lack of feedback response"? I apologize if this is a dumb question, but I am not a native English-speaker so the possibility of misunderstanding is evident.

I assume your issue is due phase cancellation. However, this is not as direct as stating that "open back cab Vs. closed back cab", as there are multiple variables that can cause phasing issues and phasing issues can happen even by using two similar cabinets (closed or open back). Placement and projection direction of speakers can also cause phasing issues. On some (rather rare) occasions you can have even the speakers in one cabinet be out of phase meaning that another speaker moves inwards as another moves outwards. If both of your speakers are moving in same phase (outwards & inwards) you may hear and feel the lack of dynamics and/or frequencies that is then caused by the actual soundwaves of certain frequencies being out of phase, thus reducing their volume. I know this is very general-level answer and does not give much precise and tangible info and Im happy to discuss this topic in more detail, but I would recommend that if you are unaware what phase cancellation is, check e.g. some recording related websites (or just Google) for this first.

In addition, lets check few basic things:
Does your cabs sound normal when used separately?
Are both of your cabinets the same impedance?
 
Thanks for your response.

By lack of feedback response I mean that with the combo on its own notes blossom quickly into harmonic feedback easily and is less dependant on where I am stood in relation to the amp/cabinet. With both cabs attached this seems less prone to happen easily.

I have looked online and yes was suspecting some degree of phase cancellation as the cause though its not severe enough to be true out of phase.

Both speakers are same impedance, 8 ohm. K-100 is rated 100W and Governor 75W. yes both cabs sound excellent on their own.

Its an odd one as I say with both cabs the overall sound is huge, but it feels less responsive in certain ways.

I will keep trying it out and experiment with extension cab positioning/orientation.

Regards
 
Interesting :confused: .
And when used simultaneously, both of these 8ohm cabs are connected to the 4ohm outs of the amp (2x 8ohm = 4ohm load)?
 
Of course. Plugged into the correct jacks for sure.

Was going to do a test last night but the venue was odd shaped and it wouldn't have been fair to the band to have both cabs plugged in.... I am way too considerate..... :rock:
 
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