[DR]

Jim,

There are other instruments that get in that danger zone also. The lowest E string on a Guitar I believe is about 80 or so. Too close for comfort.

I hope your new pre amp works out well!

You know it would be interesting to see a variation of the Sapphire with it's silent box and Scan Speak's that is down 3 db at about 65. The Force would integrate without crossovers. But then again, I would have to buy another pair of speakers I don't need!

Dave

[DSK]

DR & Jim,

If your subs have a 24db/octave LPF and are set below 80hz, you will not hear any localisation of the sub. You may find, like I did, that even using the 85hz HPF the optimal setting for the LPF of your sub (to get a flat xo with mains) will be quite a bit lower than this ... have a look at the subwoofer on my graph above. When I purchased the HPF's I bought a pair of 85's and a pair of 65's fully expecting to end up using the 65's as my sealed mains are rated at -3db@53hz or so. I also feared localisation of the sub and degredation of detail in the upper bass and lower mids of bringing a sub too far up in the frequencies. For these reasons I very nearly went straight to the 65's without trying the 85's. However, having heard the 85's now, properly dialed in, I don't feel tempted to repeat the process with the 65's as I assume that even if I was lucky enough to be able to get the xo as flat, I would simply be putting more bass load back on the mains ... and for no reason as there is no locatability of the sub or negative effects. ... just the opposite in fact.

These issues are extremely room and system dependent. I know that Mike saying "try both" might sound like a bit of a cop out, but it really is true. Of course, if your mains go down further than mine, the 65's may well be better suited to your system.

All I can say is give it a try, but measure it properly before thinking you have achieved the optimal blend. Good luck 

[DR]

DSK,

Thanks for the insight. We may be comparing apples to oranges however. The Sapphires are room sensitive to about 38 Hz (see Grillers comments on his thread). In a normal size room they require no sub. Your sealed boxes don't go that low.

I have a Hofner Icon Bass and I can tell you I can localize it easily to 42 Hz and below with overtones. I have 6 electric guitars and 2 fine acoustics and can localize the low E anywhere.

It isn't always charts, it is the ears and head.

This is getting real interesting though over a $30 item isn't it? Great conversation!

Dave

[jrebman]

Guys,

Yes, great discussion, and timely too as this really is the next big change to my system.

I hope I didn't come off like I was dismissing Mike's comments out of hand -- just that it always helps to see what others have done, because I can definitely see where these things can be very system/room/taste dependent.

I'll just say that the ACI room at RMAF last year -- where I first heard this setup, and which ended up in me buying the package even though new speakers were about the furthest thing from my mind, was one of the best integrated sub/satellite systems I had ever heard.  Of course I made the mistake of assuming the sub was playing when I went into the room, but then when Mike actually turned it on, I was prepared for the worst, but all that really happened was that the bottom end filled in so very nicely without disturbing the rest of the presentation.  That's when the gears started to turn .
This is just one of those things that has to be tried in the system to see what's going to work best.  Didn't Mike just say that .

-- Jim

[DSK]

...The Sapphires are room sensitive to about 38 Hz (see Grillers comments on his thread). In a normal size room they require no sub. Your sealed boxes don't go that low...

Dave, not sure what your point is here... the fact that my sealed mains don't go as low would mean that I should need to be bring the subwoofer up higher than you would. So, if everything is set up properly, you should have no locatability issues either.

...I have a Hofner Icon Bass and I can tell you I can localize it easily to 42 Hz and below with overtones. I have 6 electric guitars and 2 fine acoustics and can localize the low E anywhere...

Yes, but I think this is a different issue... in this case the fundamental and harmonics are all coming from the same place. In the mains/sub example, the harmonics are coming mostly from the mains so that is where your ears/brain will think the instrument is.

[doug s.]

i'd recommend using an active electronic x-over.  it should be more transparent than passive, imo.  and, my experience has been that, even crossed as low as 60hz, a single sub is locatable in a system, unless centered directly between the speakers.  also, two subs is the way to go for audio, imo - better soundstaging, less distortion for equal spl's, & easier to integrate into a room, w/the low bass coming from two distinct locations.

doug s.

[jules]

'd recommend using an active electronic x-over.  it should be more transparent than passive, imo.  and, my experience has been that, even crossed as low as 60hz, a single sub is locatable in a system, unless centered directly between the speakers.  also, two subs is the way to go for audio, imo - better soundstaging, less distortion for equal spl's, & easier to integrate into a room, w/the low bass coming from two distinct locations.

Um, yes, but this might just cost a tad more than $30 

jules

[NewBuyer]

i'd recommend using an active electronic x-over.  it should be more transparent than passive, imo.  and, my experience has been that, even crossed as low as 60hz, a single sub is locatable in a system, unless centered directly between the speakers.  also, two subs is the way to go for audio, imo - better soundstaging, less distortion for equal spl's, & easier to integrate into a room, w/the low bass coming from two distinct locations.

doug s.

Ditto on all of this. I plan to be going the two-subs route soon, for all these listed reasons. I hope that an active X-over will be transparent with no phase issues, which I believe can be found with Linkwitz-Riley designs? But this is much more relatively expensive, and not nearly as convenient, as the passive approach.

[Mike Dzurko]

I've been stating for many years that stereo subs for two-channel is the way to go if funds and space allow. . .  certainly agree there.

However, I'm at a loss as to how an active XC with ICs, transistors, tubes, circuit boards, etc and lots of passive components is going to be MORE transparent than a simple passive filter with minimal components? 

[NewBuyer]

I've been stating for many years that stereo subs for two-channel is the way to go if funds and space allow. . .  certainly agree there.

However, I'm at a loss as to how an active XC with ICs, transistors, tubes, circuit boards, etc and lots of passive components is going to be MORE transparent than a simple passive filter with minimal components? 

Hi Mike!

Me too - it seems like electronic X-over couldn't possibly be as transparent sounding (?) - I am mainly interested in trying it due to the steeper crossover slope to the mains, and hopefully having level controls that can be used for fine dialing the non-remote-controlled stereo subs.

Pardon me if this is a dumb question - but I'm wondering, are active X-overs ever used within powered subwoofers? I'm sure it would be more expensive to implement, and for all I know, might not sound as good. I noticed that active X-overs are used within pro-audio active speaker designs, with many associated (claimed) benefits - and since a powered subwoofer seems a type of active speaker, it got me wondering about this internal passive/active X-over question...

[doug s.]

good active crossovers are transparent because of hi signal to noise ratio's, extremely low distortion, & they offer gain.  i would have thought a simple passive x-over might also be transparent if used before the amp, but what spons said makes me wonder...  i have never had any issues of a flattened soundstage or reduced treble using marchand or deqx crossovers, fwiw...  (and yes - active x-overs are certainly a lot more expensive than passive devices!)

and, yes - you can use active x-overs w/powered subs.  yust have your sub's x-over set at its max position, & set the active x-over to be preferably at least an octave below that of the powered sub.  when my living situation precluded the use of my vmps larger subs, i made do like this, w/a pair of powered yamaha subs, their x-overs set at their max 160hz position, & my marchand x-over set at 60-80hz, depending on the main speakers being used...

doug s.

[Mike Dzurko]

Hi Mike!

Me too - it seems like electronic X-over couldn't possibly be as transparent sounding (?) - I am mainly interested in trying it due to the steeper crossover slope to the mains, and hopefully having level controls that can be used for fine dialing the non-remote-controlled stereo subs.

Pardon me if this is a dumb question - but I'm wondering, are active X-overs ever used within powered subwoofers? I'm sure it would be more expensive to implement, and for all I know, might not sound as good. I noticed that active X-overs are used within pro-audio active speaker designs, with many associated (claimed) benefits - and since a powered subwoofer seems a type of active speaker, it got me wondering about this internal passive/active X-over question...

Powered subs generally have an active low-pass filter, generally adjustable in frequency. In the case of the Force XL and Titan XL, there are two adjustable second order filters which when used in tandem result in a fourth order LR filter.  The Force and Titan XL also have a fixed, 100Hz second order high-pass. We generally recommend using the passive filters instead  . . .  the internal, active filter is not completely transparent.

[Mike Dzurko]

I received the 65hz filters yesterday and have been experimenting with my Vienna Acoustics Beethoven/Titan XL system since then. Until yesterday I had been using the speaker-level output adapters from my amp into the Titan and using the sub's crossover to fill in under the mains. Intermittantly I have tried stuffing socks in the Beethovens' rear ports to smooth the transition but best results so far have been achieved without them.

To assess the sonic impact of the filters alone I disconnected the sub completely and inserted the filters into my Odyssey Khartago SE and hooked up my Cardas Golden Cross interconnects. A surprising amount of bass and warmth remained, but the addition of the filters flattened the soundstage and reduced treble detail pretty dramatically. I then added a solid Y-adapter to the outputs of my Quad CDP-2 that I use as a preamp and listened again before I hooked up the sub. The result was additional degradation similar to that of the filter alone.

Undeterred, I finally hooked up the Titan and dialed it in using some of my favorite bass-integration music like "Fragile" from Kenny Barron's "The Moment" and "Twilight Song" from his "Night and the City" duet album with Charlie Haden. Wow. Really articulate, deep bass like I have never heard before and no midbass muddiness at all.

My overall conclusion is that I can't accept the degradations that the filter and Y-adapter impose in order to achieve the improvement in the bass and midbass. It is simply a matter of personal priorities as I can understand how another person could feel just the opposite. I returned my system to its original state with the sub running off the amp outputs with no filters or Y-adapter and it sounds pretty darn good. Bass isn't as well integrated but the magical soundstage has returned.

Andy

DSK already covered this, but to re-iterate:  The loss of soundstage and degraded treble performance are pretty much what you do hear when you roll off the bass. Add the bass back via the subwoofer and those aspects of performance will be back inline with how they sound be. Psychoacoustically we make adjustments whenever we don't hear the full spectrum.  Also, keep in mind that the passive filters have an insertion loss of around 3db. So, when they are used, the pre amp volume will need to be adjusted upward this amount to compensate.
Accurate listening tests of filters is really tough . . .  because by design they are filters and are supposed to have a major impact on the  frequency response.  We used to spend countless hours on this . . .  at this point I am fully satisfied that the passive filters do exactly what they are supposed to do with extremely little if any sonic degradation . . .  and any possible downside is far surpassed for the improvement they make to the overall capabilities of the system.

[DR]

Hi,

I certainly am no expert, But I just wanted to attest to the fact that I have been using Mike's filters in a variety of systems in a variety of rooms for many years. I have never detected a degradation of any sort - with one tiny exception. Cross over point.

As Doug mentioned if the Sub were in the center then localization is not a problem, so let's assume that. However, if the crossover point to the mains interfere with speakers voicing, then that is bad.

The Vandersteen 2ce's were a speaker I owned that were touchy about this so they never saw the 85's. The Emerald's voicing seems to remain the same using the 85's. The Sapphire is such a beautifully voiced speaker that in my opinion the 85's change it. So I use the 65's. This is all independent of the localization thing.

My two cents.

Plus as Mike says, If I had the room I would have another Force XL.

[spons]

I am certainly not a golden ear, so I trust from what you all have said that what I heard was a result of the sub not being dialed in correctly. I just re-connected the filters and am going to spend a few weeks fiddling around with my setup.

Thanks for all the advice. I did hear a vast inprovement in the bass, midbass, and lower midrange regions with the filters inserted, so if I can retain these benefits without much if any cost in treble purity and imaging I'll be set for a good long time.

Andy