SPEAKERS, SPEAKERS AND MORE SPEAKERS.. BUT NEED BASS.?

@rauliruegas wrote: "The main reason to integrates a pair of self sealed ( not vented ) powered subs in true stereo fashion along any passive main speaker in a home audio system is to reduce IMD in the speaker/system and you can achieve that main target only through a high pass filter ( teflon cap. ) like the one @bdp24 advise."

I think that what works best depends on the specific situation.

And in particular regarding vented vs sealed subs, again imo it depends on the specifics. I can go into detail if you’d like.

"According with a scientific JBL studies the ideal number of subs in a home system is four subs and at least two. The number of subs makes evenly the room/system bass frequency range response."

Yes, I’m quite familiar with Todd Welti’s study. I manufacture a four-piece subwoofer system called the Swarm, and in my setup guidelines I include Welti’s recommendations along with several asymmetrical suggestions. Welti did not investigate asymmetrical placements but Earl Geddes has.

Briefly, the in-room smoothness goes up as the number of intelligently-distributed subs goes up, and smooth bass is "fast" bass.  So two subs are twice as smooth as one, and four subs are twice as smooth as two, and eight subs are grounds for a divorce.  So four subs is probably ideal! 

Duke

@rauliruegas said, "I just can’t imagine any situation in a passive design speakers where subs can’t help to lower speakers IMD that comes with additional benefits as lowering the speakers THD and gives the amps to works way better when are liberated from the low bass range..."

This was in response to me saying "I think that what works best depends on the specific situation."

I’m NOT saying that lowering intermodulation distortion and liberating amp and speaker from the bottom two octaves isn’t beneficial. IT IS!

But in some situations, the circuitry necessary to high-pass-filter the main speakers causes more degradation than it’s worth. For instance if the mains and amp have 10 dB of headroom beyond whatever peaks they’re likely to see then the benefits of a protective high-pass filter may be negligible, and if the speakers are particularly revealing any resulting degradation in the signal path may be audible and objectionable. So imo, "it depends".

Also in many situations budget is a factor. Maybe a really nice high-end signal processor would make a great and super-transparent highpass filter, but is that always going to be the smartest place to spend the next however many hundreds, or thousands, of dollars? Once again, imo "it depends".

Finally there is this possible consideration: An intelligently distributed multi-sub system can significantly reduce room-interaction peaks and dips in the modal zone, and an unusually capable pair of main speakers may have enough useful low-end to contribute to this modal smoothing.

In my experience a fair number of people who are using a protective highpass filter, be it digital or analog, end up pursuing whatever offers the next level of transparency. This may mean hot-rodding the parts inside their device, or it may mean replacing it altogether with the latest-and-greatest. Anyway this tells me that protective highpass filters do have audible downsides.

By building "satellite" speakers that arguably don’t NEED a protective highpass filter under most conditions, I’m giving people the OPTION of not using one. Budget is an issue for most of my customers, so maybe they can defer the expense of that high-end processor for a while, if that’s what they want to end up with.

Duke