Do you think you need a subwoofer?

Dear Pryso: The range ( high/low )i the IMD depends mainly on the quality of the woofer driver and how low goes on the bass ( deep bass ).

Normally if the speaker croosover is set at 160hz to the mid-bass driver seems to me that that bass woofer could goes at least to the mid twenties.
The frequencies below 45-50Hz needs a biger woofer excursions that 50hz-up, these biger excursions are the main " culprit " ( not the only ) that the IMD goes high, so if you liberate this woofer from 50Hz down you will have improvement/benefits for lowering the IMD in the main speakers and a better main amplifier performance ( btw, we have to think that because a speaker does not have response, say, at 25Hz this does not means that the amplifier is not working in that frequency and below it. ) and obviously a better quality low bass performance through the dedicated subwoofers.
In this ( yours ) example the high-pass could be at 50-55HZ and the low-pass ( sub's ) at 80Hz, this depend if the filters are first, second or third order. So almost always we can have benefits through the sub's integration with passive main speakers.

As always the differences and improvements/benefits are system dependent and there are no precise " rules " on the subject other than " test and error ".

Regards and enjoy the music.
Raul.

Dear pryso: IMHO I think that there are some non know-how on the critical importance for the low bass reproduction.

Through the years I heard several full range speakers ( that goes down to 20Hz. ) including mines. In the last year I heard Wilson ( MAXX/Alexandria ), Acapella Triorlon, MBL 101, Dynaudio Temptation, Soundlab and Avalon " something " ( I can remember the model. ) etc, etc.
All very good speakers and if you never had/have the experience/opportunity to hear/heard a good powered subs you can/could think that any of those speakers is the only " thing " you need on the bass subject, all of them are good performers in the low bass but none has the quality level performance of a good powered sub.

You can say: so what? these speakers are great ones and we don't need anything else.

For me ( I can be wrong ) what define/makes the difference between ( talking about speker performance ) good speaker performance and very good/excellent one is its quality performance at both frequency extremes and for these frequency ranges the low bass maybe is the more critical because is the one that contribute the more to " pollute " the whole speaker performance. This is not something that someone tell me, this is my experiences about.

So IMHO till we have the right quality bass response by our each one speaker system we can't speak that we have a very good/excellent quality performance audio system.
Of course that every frequency range is important to the quality performance but I think that the low bass range is the one that can do more for the " bad ".

Regards and enjoy the music.
Raul.

Dear Pryso: The big Evolution Acoustic speakers are a good example of a full range design that does not needs external powered sub's because things are that the Evolution speaker design already have it and integrated to the speaker.

This Evolution speaker design is a good example where the designers take in count the critical importance of the low bass subject and the need that that bass range will be handled by a dedicated woofer/amplifier ( like the sub's. )

I can't say for sure the croosover frequency Evolution's woofers that handle the " sub " bass but maybe lower than 80Hz or maybe the owner can choose it.

Perhaps M. Levigne could share this info with us and can give us his thoughts/experiences on the sub's/low bass whole subject, could you Mike?, thank you in advance.

Regards and enjoy the music.
Raul.

For me as our living room is really big(11X12)I was hesitant in trying 2 subs.to some folks I might do things backwards.
in four years we bought a 900sq.ft. house,and of course I love audio.So I have been buying gear suited more for a bigger room.My speakers are revel 50as,Bryston 28B-sst+7B-sst+1X4Bsst,2XDD-15 subs.One which I have been using just for the .1 for movies.Raul suggested trying the 2 in stereo.
As I don't have much room I tried it in front of my speakers.One sub was good if you were sitting where I was sitting.Using two in stereo solidified the bottomend(Way more) and gave me way more soundstage depth,almost a 3-D effect.I imagine some are thinking,two DD-15s in a 11X12 room.And why i am I not using satellite for mains.the revels put out a nice bottom end(stereo direct)But adding a sub makes it way more solid,like a we'll recorded kick drum or bass guitar.adding two just makes it very enjoyable(more like a live event).I have no boominess,bloat,no nasties.I could only imagine when we add on to our house or buy a bigger house,how much more I'll get out of her.I thought two subs
might be too much(quite the opposite if you listen and be patient when adjusting the subs).I do Y cables out of my R+Lpre to amps and subs,speakers set to large.I have the subs X-over at 64 hz,as my speakers supposedly go down to 32-34 hz.I will try the X-over at 80hz and see.I like where their at now,very emotionally musically satisfied,BUT.Anyway it was a great surprize integrating the other sub,only one problem,I need another sub for my movies now,Thanks Raul.

Dear Drummermitchel: Nice to see that your sub's stereo integration was/is sucessful, congratulations.

Like you say we have to " listen and be patient " to achieve good results.
You even still have " land " to make a little change try it and listen for an improvement or not: to use the high-pass on your DD ones to liberate ( lowering the IMD on the main speakers ) your Revel's from low bass. You can do it and see what happen.

Regards and enjoy the music.
Raul.