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Hi,
I've been making IR sets with left, center, and right emitter positions in a rectangular "room" in I.M..

Often times the left and right IR seem some what symmetrical.  The Center channel however often exhibits and initial spike that favors one side or the other.  While theoretically the response might be expected to be symmetrical in a simple rectangular room where the emitter and receiver are on a the long axis, I can think of many reasons why this is not easy to achieve in modeling.

With that in mind, I am curious about your ideas regarding good practice while preparing the IRs.  Is there any good reason not to use a wave editor to discretely edit one side of the initial spike to provide some sense of symmetry?


thanks,
mike

Well, Impulse Modeler is not good and can't be really good at modeling direct signal IRs since to model that one needs an infinite number of rays.  It's up to you whether to edit or not edit manually, but I can't really suggest to create impulses with direct signal with IM.

Ok thanks,

I''m not purposefully trying to do so...  I merely interpreted the fist spike as the direct source... or perhaps the first reflection?

So, what I am asking about is the spike... what ever it is.

But now, you have me curious?  I'm using the sync tail feature and generally pleased.  I have the direct sound choice set at "Off" which I thought meant that it defaulted to the equal of "8".

Maybe there is no direct sound and I'm just confused?

In general I'm pleased using the sync tail and the front end as it's created by I.M.

If you have any suggestions that you might share please pass it on. :-)

best regards,
mike

If "direct sound" is Off, the first spike is not a direct spike - it is a reflection.

Thank you for helping me understand that.

I want to be clear that I am not trying to be critical of I.M. but I'd like to readdress the original question.

With regard to the circumstance where the emitter and receiver are snapped to the central length ways axis of a rectangular room... it seems appropriate to make some small edit to the wave form to reinforce a sense of bi-symmetry.

I'm just wondering if that approach is in sync with the general intent of I.M.  Is the lack of symmetry just a symptom of some practical limitation of modeling (once again, this is not a criticism) or is it meant to portray some phenomenon that I am not accounting for.

If it's just a limitation of modeling it seems that it would be good practice to try to match up the initial spikes in post processing.

Thanks very much for your support.

best regards,
mike

You may try to increase ray count to maximum to see if the generated impulse becomes more symmetrical.  Post-processing is not a requirement.

Another aspect is the emitter cone and angle - if it isn't pointing the receiver symmetrically, the impulse may become asymmetric.  But unfortunately, emitter cone and angle can't be defined precisely in IM.

Thanks again, I will experiment with Ray count etc.

I've been using the full angle of the emitter (which I assumed was 360* although it appears graphically as 350+/- and I've been attempting to orient the graphical "gap" along the central axis as well.

I really like I.M. and very much appreciate your having made it available.

thanks,
mike

OK, you are welcome!