Shane Morales

Large speakers + sub vs. Small speakers + sub

Much Rambling
I'm starting to get into the "knows enough to be dangerous" level of HT Fandom and as various things are cleared up in my mind a whole new set of questions arise. For instance:

I understand the idea that basic physics limit levels of bass speakers can produce (as in this thread in the FAQ). And, y'know, that's something that is easily and readily observed. Pretty much the principle that guided my speaker purchase - I went with floorstanders because they sounded better to me than book shelf speakers.

Enter the sub: it seems recommended to set your speakers as small in your receiver setup and let the sub do its thing. Sure, fine, sounds great.

The Actual Questions
But what I'm wondering now is why bother buying floorstanders if you're just going to set them to 'small' anyway? In my case, I got Mirage OM7s and a SVS20-39PCi. Wouldn't the Omni 60s and the SVS sub give me about the same sound, at less than half the price, if the OM7s are set to small?

:::Shane
:::nineshadoweyes.com

John Garcia

This entirely depends on your listening habits and your system's flexibility.

If you have the ability to adjust your main to sub x-over, you can get very good results with large mains. A bookshelf speaker that does not cover well enough below your x-over could give you a dip in frequencies near the x-over point. With a floorstander that covers well below the x-over point, you do not have to worry about this. Figure that with an 80Hz x-over, the main speakers should be able to handle nearly to 40Hz, depending on x-over slope. With a higher slope, they may only need to extend to 50-60Hz, which most decent bookshelf speakers can do.

For a lot of my music listening, I don't have the sub on. I have large bookshelf speakers that have decent enough bass response to get away without the sub.

Regardless of the frequency response of the mains, unless we are talking into the upper to mid 20s, I would say a sub is a necessity for movies, and tolerable for music.

Lew Crippen

I second John’s first sentence. Most music (except for pipe organ and such) does not go down to the last octave or two. But modern movies make a lot of use of that frequency range. So if you mostly listen to music, a pair of good speakers (especially ones designed for music) really won’t make much use of a sub.

Typical very good, but not audiophile speakers will be flat down to about the last octave (40hz) or even a bit lower (35hz–38hz). So for music and even for pretty good HT you will not miss a subwoofer.

Good subs are designed to be flat from 20hz or 25hz to about 80hz or 100hz., so in theory you will have paid for reproduction in the 40hz–80hz range (the second octave) twice.

However not all (even good) speakers are as flat in your room as the advertising brochures indicate. And crossovers typically are not binary in nature (at the crossover point), so even if your crossover is set at 80hz your main speakers are still being used to reproduce sounds perhaps as low as 60hz and your sub is being asked to reproduce sounds as high as 100hz.

This means that even if your main speakers are rated flat to 40hz (and this will be a pretty good speaker) they will still be being used at 60hz (assuming an 80hz crossover) and 60hz may well be about as low as your mains can reproduce accurately in reality in any case.

Which means that you have lost nothing and not paid for the same thing twice. But of course in the audio world, you have indeed been introduced to a prime example of the law of diminishing returns. That is, getting a thing to be a little bit better, costs a lot more.