But when measuring final response what combo do we use? Single left or right +subs?
I have NFI. How about C+Subs? ;)
I have NFI. How about C+Subs? ;)
Good post. Thanks. I have just posted a full set of REW graphs which I believe reflect the current state of the room. One thing that is interesting is that I seem to get different results when using REW to when using OM. My OM always seem to look better - maybe I should go back to OM - LOL!
OMG, I hadn't even considered different parameters for waterfalls and spectros.
IDK. All my speakers are from the same manufacturer so timbre-matching isn't too much an issue. And I always choose identical L, C and R speakers - I can't stand it when a different centre speaker is used and you can hear the timbre change when something pans left to right or v-v. I realise that not everyone can accommodate identical LCR speakers but I highly recommend it where possible. I find it difficult enough to optimise all this without having to also cope with speakers from different manufacturers!
I hope not. I posted all those to get comments on if I was doing it right (and hopefully to attract some help on how to interpret them and what changes might be beneficial in my room, or at least what is a problem and what isn't). I would hope to not have to submit a full set every time.
Jim - thanks for this. I can see exactly what you mean. This is the sort of analysis that I find very helpful. I have to say I haven't been aware of any wandering of the image, but do remember that I only use the system for movies, and voices are rarely just dead centre as one might expect from a vocalist on a music track. In fact, I have always thought (post treatments) that my imaging was really very, very good. That is not to say, of course, that it could not be better. But for a movies-only system, do you think I would benefit from the no doubt considerable time expenditure required to improve things? If I used the system for music I would definitely adopt a different approach as any 'wandering' then would drive me nuts. But with movies, the actor is for ever (usually) moving about the screen, and visual dominance of our senses being what it is, the voice appears to follow the actor, even though we know it is actually (usually) rooted to the centre channel. So there is an element of wandering built in. I do think is perhaps easier to work with a room used exclusively for movies than it is for one used with music, or hardest of all, a room used for both.
Do you see any other problems in the 15 graphs I uploaded?
One of the benefits of REW. Once the measurements are made I can present them any whichway...
LOL. Well, yeah... it's why I wouldn’t choose speakers like that for a movies-system. One of the influential factors in choosing my M&K S150s is that they are an identical set across the front. As were my last speakers and the speakers before them and the speakers before them.... centre channel is so important for movies of course. Perhaps THE most important channel of them all.
Ah - first problem. My MLP is not, and cannot be, centred. (: Due to the crappy little room and the way it is, I have two listening chairs and neither can be in the centre spot. I have cheated a little and moved mine closer to the centre than the other (rarely used) chair but that is all I can do. It may be, in general, that the diktats of my room prevent me from ever getting a 'perfect' response (where perfect is defined as something like your own for this purpose).
I assume that we are stymied by my observation above...
Well, that is some good news then at least :) Thanks for your help, as always.
Thanks Nyal. What plus or minus dB figures are you after in either case? Ideally I mean?
OK, guys, no one has done anything to make my headache any better.
This is where I think we are:
- Below 300Hz, measure all speakers that contribute to bass response, i.e. left+right+subs, or center+subs. Always use unsmoothed data. Use these measurements to produce waterfalls, spectrograms, and decay graphs.
- Above 300Hz, measure left, center, and right speakers individually (with or without subs) to avoid undesirable interactions between speakers which gets worse at higher frequencies. Publish frequency response graphs using 1/24 smoothing to observe any remaining issues, or using 1/6 smoothing to get a general feel of the progress that has been made (whatever that means).
BTW, regardless of what some of you think, the subject of the interaction between left and right speakers was raised by me several weeks back. I was noticing a strangeness above 10KHz in the left+right graph that was not present in the individual left and right graphs. That precipitated a discussion involving the importance of making sure the mic was placed in exactly the center between left and right speakers. I believe Jim contributed to that discussion, as well as several others (sorry, don't have the time to dig out the original posts). Since then, I have experimented several times by taking a left+right measurement, observing the flatness above 10KHz, and adjusting the mic in small increments either left or right, observing the effect on the graph's flatness. The mic's position can make a significant difference with only a slight movement. So, in retrospect, someone might be chasing what looks like a high frequency issue, when it is simply the interaction between the two speakers.
Make any sense? Whaddya think?
Interesting. I have a fair number of mono albums and I always play them back through the stereo pair of speakers. I shall have to listen more closely and perhaps play back through just one speaker and compare it with playback through both and see if I can hear a difference. Aaaaagghhh.... so far I have resisted going down the rabbit hole in the room where my two-channel music system lives! :)