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Help. Channel imbalance

If you have found the test record it still should be obvious that what is coming out of the tweeter is at the same level. Even better if you have a sound level meter. I suppose there may be other tweeter faults that reduce level, but don't kill it entirely or perhaps a fault in one crossover. Anything else I would have thought your left / right swap would have shown up?
 
They can and do sometimes just go down in level... sometimes dried up ferrofluid but can be a past overload that has caused a few shorted turns.

Try switching over input channels, speaker outputs on amp etc and see if it effects which side the problem is with.
It could possibly be a very odd room with extremely asymmetric sound absorption properties and may need a wholesale re-arrangement of speaker position etc.
 
The penny dropped this morning when I realised I could disconnect my drivers at my external crossovers, one by one. At midday I hastily improvised a 5 minute test and came to the following conclusion : My problem has nothing to do with my tweeters, nor indeed with my mid woofers. It is the room after all and more specifically I suspect it is the fact that say 15 cms to the right of my right hand speaker the rear wall ends and opens up into an alcove with 3 doors leading off. So in other words the reinforcement of the rear wall is not symmetrical as far as bass/mid bass are concerned because the rear wall extends to the left of my left hand sp'eaker at least another metre and a half before reacjing the corner.. What I do not understand is how this would affect the sound because when I connect just the right hand mid woofer the sound seems to originate to the left hand side of the bureau which stands between the 2 speakers - go figure - which explains why the left hand speaker has always seemed predominant - it provides its own bass and in seemingly within its own sphere of influence itsreceives somehow half that of the right hand speaker. Either that or the bureau is acting like a sound box which I doubt because there are no signs of vibration or resonance.
So after this long winded build up how is the rear wall important to speaker performance. By the way according to Peter Comeau my speakers are designed with a 3dB bass reinforcement through proximity ( 6 inches max ) to the rear wall
 
Bass is essentially omnidirectional with a spherical wavefront. The bureau sticking out from the wall brings that wavefront forward. Simples.

The 3dB reinforcement is nothing more than the normally backward travelling wave being prevented from going backwards, it is instead reflected forward and adds to the forward travelling pressure.

Note: bass frequencies have loooong wavelengths, they can reflect many times over at 340m/s within a regular sized room and you are very unlikely to ever experience "clean" anechoic-like performance.
 
Thanks but my question is “how does the fact the free wall space to the right of my right hand speaker is About 15 cms while to the left there Is about 2 metres affect things ? In other words I cannot position the speakers symmetrically wrt the wall behind.
My bass response is fine , it’s the central imaging that’s kyboshed.
Is a balance control my only friend.
 
Can you swap the speaker leads at the back of the power amp and see if the same situation happens on the right hand side now instead of the left.
 
Chris said:
Thanks but my question is “how does the fact the free wall space to the right of my right hand speaker is About 15 cms while to the left there Is about 2 metres affect things ? In other words I cannot position the speakers symmetrically wrt the wall behind.
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Baffling ;) innit. Block up the alcove so that the reinforcement is symmetrised and things should improve.

Also, your bass response in room is not "fine", it may have adequate quantity and decent quality but is clearly skewey. 250Hz is a bass frequency, middle C on a piano is 261.6Hz fundamental (1.3m wavelength).
 
Eyebroughty said:
Can you swap the speaker leads at the back of the power amp and see if the same situation happens on the right hand side now instead of the left.
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Yes, will do but so far I haven´t been able to reproduce / transfer the predominance of the left hand speaker over to the right when swapping leads into or out of my phono pre. I can even swap speaker leads into my speakers as my underfloor conduit "surfaces" at a mid point between my speakers and both use speak-ons. Will do so asap.

That´s whu I blame it on the room / furniture.

It really is weird when I connect only the right hand mid/woofer - everything else disconnected and the sound comes mysteriously from a central point, seemingly somewhere inside the centre bureau and as I move to the right I only become conscious of the right hand speaker ´s existence when I´m stood next to it.
 
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Chris said:
Thanks but my question is “how does the fact the free wall space to the right of my right hand speaker is About 15 cms while to the left there Is about 2 metres affect things ? In other words I cannot position the speakers symmetrically wrt the wall behind.
My bass response is fine , it’s the central imaging that’s kyboshed.
Is a balance control my only friend.
Click to expand...

It's going to be more complex than simple rear wall reinforcement. Because in effect you have two rooms effectively joined together you are going to have a complex set of room modes caused by the length, width and height dimensions of both rooms and the combined room dimensions. These are going to reinforce some frequencies and subtract from others and it is also quite likely given the different proximity of each speaker to adjacent walls each speaker will excite different room modes and be affected by all those being produced differently as well. At least up to what is known as the Schroeder frequency.

To really find out what is going on you need to measure your room with a calibrated mike using something like REW software. REW is free, but it is quite a high learning curve to measure and interpret the results correctly.

You may get a bit of an idea of what is happening with the room modes by putting the dimensions into Amroc: https://amcoustics.com/tools/amroc?l=431&w=370&h=237&sa=false&so=false&fo=300&fu=35&r60=0.6 but it can really only cope with three sets of dimensions at a time.
 
Not much point in swotting up on all this unless you can act on the results. I remember reading a thread where a bloke had ended upfitting castors instead of spikes and I´ll have a go now that my wooden floor looks like a severely used dartboard and by moving the speakers about and a bit of balance control, try and find the best compromise. Then with the aid of the castors I can wheel the speakers in and out from their normal position against the wall when needed. It´s quite a relief actually to know that I´m still crazy after all these years.
Just nobody mention the words "channel imbalance".
 
One simple thing to try is to move one speaker closer to you.

Have heard that cure an imbalance similar to what you have.
 
I've been going through much the same problem. We've recently rearranged the room, and sit much closer to the speakers. I now notice that, to get an even stereo image, I have to set the balance over towards the left speaker a fair way. Having gone through the usual checks of speaker, connections, sources etc., I've narrowed it down to a few factors - I sit slightly off-centre to the right, I'm a bit deaf in my left ear, and the room's not an even shape around where the speakers are positioned. I tried sitting really close, midway between the speakers, and the uneven effect almost disappeared. I'm now satisfied, and content to listen with the balance control off-centre.
 
Eyebroughty said:
One simple thing to try is to move one speaker closer to you.

Have heard that cure an imbalance similar to what you have.
Click to expand...
That's what cured my image imbalance, after I had eliminated any issues with the equipment.

One loudspeaker is now about 0.2 metres (8") closer to the listening position and the image is central and stable. The arrangement looks just a little odd at first even though the listening position is 2.7 metres away. But in relation to the room's asymmetry I got used to it and it is very effective.
 
Well now someone is going to have a good laugh. Remember when Linn used to say never to have another transducer, speaker or even a digital watch in the same room. Well I have just tried listening to the right hand channel only of my system in my acoustic mess of a room with the roll top bureau desk thingy still between my speakers BUT WITH THE DRAWERS OPEN rather than shut tight and you guessed it: double bass on Portrait in Jazz by Bill Evans Trio has now become an instrument with attacking edge most of the time rather than a blobby mass and deeper too and I swear I can now distinguish a metallic shimmer on cymbals. Should I get a life or has anyone else experienced anything similar? No we are not talking about obvious vibration in sympathy with an adjacent source as in vibrating windows etc. but something which apart from buggering up the bass on this recording also displaces my central image.
This weekend I shall play without my drawers in place (ooer missus) and if I feel up to it I might even move the bloody desk out of the room and see what happens.

Does anyone sell hifi-tuned straitjackets ?
 
Great innit? Just when you think you are getting your head around something, along comes the curve ball.
 
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