We're trying to set our standards, and I believe input from the experts (you) is what I'd really like. Thanks for your suggestions!
I assume you’re dealing with your customers asking WRT your equalizer? It is a bit of a challenge, I’m sure, since you’re dealing with people with both manufactured subs and prodigious DIY fare.
There are some “accepted” rules of thumb, like you should only use cutting filters and minimize boosted filters, if they are used at all. This “rule” is based on the faulty premise that boosted filters places increased demands on the sub, while subtracting filters do not. But if you are equalizing to eliminate say, an 8 dB resonant peak at 40 Hz, you’ll find that afterwards your sub is not loud enough. What will you do? Adjust the sub level higher, of course, to compensate. Well, say goodbye to the “free” headroom you supposedly got by cutting the peak.
Another “rule of thumb” is that you shouldn’t boost a ported sub below the tuning frequency of the port. But the truth is, the program material in a movie can do the same thing despite equalizing “by the rules.” For instance, early in the latest Batman movie
Dark Knight there is an
extreme level of bass generated in the 25 Hz range and lower. Well, I’ll bet anyone with a ported sub tuned at 30 Hz or higher experienced some nasty noise there. It doesn’t matter if the low frequency boost comes from an equalizer or the program – it’s all the same to the sub.
As you can see, at the end of the day the “accepted rules” don’t matter much. When it gets right down to it, only rule that matters is “headroom,” because any equalization places additional demands on both the amplifier and the driver. You have to have headroom to spare – both before and after equalization, but especially afterwards. If not, there will be rude noises from the sub during demanding passages.
When advising customers on equalizing, I’d consider the sub they’re using. With few exceptions, most subs with small 8" or 10” drivers should keep equalizing to a minimum. The same holds for subs with larger drivers, but low-powered amplifiers.
Regards,
Wayne