Originally Posted by m-fine416
At what frequency are you matching the levels? The response curves are not going to be the same, so are you matching the the highest peak, the lowest null, the level at 40 hz, an average over 1 octave, a half octave, or, whatever your C weighted $19.99 Radio Shack meter says?
The response curves are never going to be exactly the same but then a gain matched approach won't yield similar response curves either if both are in dissimilar locations so you are knee deep in the same predicament.
Matching sound pressure levels could fix problems within the response at the listening location while also offering higher peak SPL which one could then EQ. Perhaps not. Proper positioning and measuring the results are still paramount to achieving decent results with either method.
It's not like gain matching has some inherent superiority over level matching despite your so-so; the only advantage is that each sub theoretically will have equal drive levels (which could be less than 5% for all you know) which equates to equal work load per sub.
Or, alternatively, with a level matching method, slightly greater work load per subs but better in-room coupling which equates to 'not much worse of a situation if you ask me but, well if you had to ask, actually higher SPL as a byproduct which one could then equalize to their hearts content in a number of ways'.
Of course a level matching approach could also yield equal drive levels because the sub's could possibly be co-located in which case you gain full coupling and equal work load per sub in which case you have a level matched and
gain matched set up. Harmony.
Or....one sub has a hole at 40 Hz of 10 db's and another has a peak of 5 dB's at 40 Hz. Gain matching both in that scenario won't do jack to alleviate the 5 dB deficit. Even though you aren't really looking at two response curves but one combined curve, the combined gain at one location could yield piss poor results.
You can then equalize at the listening position but comb-filtering will invariably mess up the results so you are actually correcting things which don't or shouldn't necessarily be corrected.
A $19.99 Radio Shack meter when using the correction files for FR compensation can allow for accurate enough results, although it's not surprising that you would correlate price with quality. I don't use the Radio Shack SPL meter as my primary meter. I use the Behringer CM-8000 with phantom preamp.
How are you determining the best location for the subs? With 2 gain matched subs you can move them around and measure FR at the seats and select the best location. With Level matching, are you re-level matching with every location you test before you measure the response?
Determinations are similar : With 2 level matched subwoofers you can 'move them around, measure FR at the seats and select best location' and
'attain the maximum level of coupling possible'. The result might not end up the smoothest (which is debatable at this point) but you sure do achieve tightest coupling of both sub's (not that I ever said that a smoother response would be the more likely result)
After you EQ are are re-level matching? If you are just using the RS or other cheap SPL meter to set the levels, they will be highly influenced by any peaks.
Whether you use a cheap SPL meter or the most expensive SPL meter on the planet, you still need some form of correction or compensation file (or calibration) to have accurate readings down low so let's not pretend here that the RS or any other meter is somehow exempt from these limitations because of price.
Cut the peaks and your level readings will be different and likely no longer matching.
Perhaps...perhaps not. Of course you have no idea as the above is anecotal at best but we can come up with a list of hypothetical suppositions that can make either method look flawed but it sure will waste time, wouldn't it ?
For all you know, a subwoofer with a deficiency within the 25-40 Hz pass band has a dip of 4 dB's which is cured when using a level matched approach and then you can EQ which will retain the benefits of coupling.
If you are cheap and lazy and just want to open up the boxes and shove the subs wherever the wife tells you, level matching might work out.
Which is contradictory to say the least as it takes longer to match equal levels than it is too simply gain match. If you are 'cheap', you'll quickly gain match, using your argument. Then you will measure...see which response is smoother, equalize...but wait, you wouldn't have matched the levels, which precludes any form of strong coupling, especially if the subwoofers are in two completely different locations, with different response curves.
One subwoofer has strong output within it's bandwidth from 20-65 Hz but another subwoofer is positioned 2-3 meters away that is also sitting in a bit of null, a null affecting a relatively wide area of the response curve so you EQ some of the peaks and are left with the null, except the rest of the range is lower than the other sub because the gain that you've used equates to higher in-room levels.
The levels are not matched at the listening location so coupling won't be achieved and you'll go through the efforts of positioning, moving and locating the subs to achieve a potentially smoother result which still precludes the full level of coupling that one could achieve.
Just plug them in, pull out your RS meter, match and go. It wont be an ideal setup, but it does not take much time knowledge or measurement gear.
Of course it doesn't because your argument precludes any other method from competing which is a pity isn't it ? Except things don't work that way in real life. Both methods, whether you like it or not, require time to get optimal results and both require some form of measurement gear to, um, perform the measurements.
Also, say what you like, if you want better coupling and maximum SPL then level matching is the way to go; you can argue until the sun comes down but any problem you cite could be duplicated with either method because the end result is dependent on the room and the location.
If on the other hand you actually want to measure the room response to select the best reasonable position of the subs, and use EQ to integrate them as best as possible, gain matching is going to be much more straightforward and it will also give you better results and max headroom.
You can 'actually measure the room response and select best reasonable position for the subs' with a level matching approach too. Of course a gain matching approach will give better max headroom, but then, no it won't. Because your understanding of wave coupling is sorely limited. Equal level and phase. Hence I said from the start that this discussion was way bigger than you.