Bypassing the "sml spkr" 40 Hz crossover for "full range" mains (1 Viewer)

[marklizard]

My Mirage M3si mains go down to about 30 Hz +/- 3db and I really don't want to give up any bandwith to my Energy sub that hits 20 Hz -3db. I know this might sound like splitting hairs to some of you who are fine with a 40 Hz crossover for your mains but my Mirage M3sis sound great without a sub and I'd rather the sub handled only those main frequencies below the Mirages, plus bass frequencies the surrounds and center speaker miss, with some necessary overlap, of course. I want to share how I have figured I might be able to get around the 40 Hz crossover limitation and I'd love to have you home theater savants with audiophile IQs above 180 to wade in on this since I am a newbie and want to raise my own such IQ. As my mains are biampable, I figure I will run my Marantz sr5005 mains speaker wire to the Mirage top ends and set them as "large" (meaning no main frequency going to the sub). Then I will run a cable from the main preamp thru a comparable (sound quality) second amp, out the second amp's sub output to a Behringer Feedback Destroyer set to cut anything above 33 Hz (or thereabouts), then to the Energy sub via a Y connector that will also be connected to the Marantz sub out. The second amp would also power the bottom end of the Mirages. Theoretically, then I would probably get a slightly better sound out of my now biamped Mirage mains, have the benefit of them sounding like unadulterated "large" speakers with no inhibiting Marantz 40 Hz crossover, and have the Energy pick up the remaining 13 Hz in addition to the cutoff bass for the surrounds and the center channel. Opinions please...remember, I am hoping to be educated so if anything I have said sounds problematic in any way, I want to know. Thanks in advance for your time.... Marantz Sr5005 Mirage M3si mains Rogers L3/5a surround Energy e:XL-S12 sub DCM CX Center Adding front height speakers

 

[JohnRice]

Elaborate theories like this rarely conform to reality. The biggest problem with your basic assumption is that you are disregarding the multiple benefits of taking some low end demand off the main speakers. It's not a small benefit. Also, I see potential phase and probably cancellation problems here, but the setup is so convoluted I'm actually having a problem getting a vision of it. Add to that the problem of balancing bi-amp outputs from mismatched amps and I'm starting to get a headache. In the end, I think you are trying to fix a problem that doesn't exist, and wasting a lot of money to do it when you would most likely get better results investing that money in better equipment used in a more straightforward fashion. For instance, using a better, more powerful amp to drive the L/R and just setting the crossover to 40Hz, which I personally think should be higher anyway. BTW, the 5005 makes a stellar "head unit" with external amp(s).

 

[marklizard]

Thanks John. When you say, "head unit", are you meaning a preamp for external amps? Still learning the lingo. The whole, probably convoluted, idea of my post was my assumption the Mirages would do a better job between 30 Hz and 40 Hz than the Energy sub. Thank you for wading through it and for your astute observations...

 

[JohnRice]

From what little I found in a quick search, that seems to be a decent sub. In most cases, it is best to let the sub do its job and take that burdon off the main speakers. I would run a conventional crossover at a minimum of 60Hz, and try 80 as well. I have no idea why you think the main speakers perform better at their extreme range than the sub, which is designed specifically to operate in that range.

 

[marklizard]

Hi John, Thanks again. The Mirages are higher end, but admittedly, they may not sound any better at that frequency range. I like the way they sound all the way down and didn't want to mess with them. But you and most of the experienced guys on here would likely say I'm splitting hairs and, like you said, adding more problems for no good reason so I am determined to listen to it as is for a while and go from there. All the best....

 

[JohnRice]

Just an FYI. My main speakers are Thiel CS 3.6 and I power them with an Aragon 4004II which provides roughly 500 wpc with those particular speakers. If Mirage is higher end, Thiel is stratospheric. They are also rated perfectly flat (+/- 0.25 db) down to 30Hz. I still cross them over at around 80 HZ.

 

[marklizard]

Thanks John. I meant that the Mirages were "higher end" relative to the Energy sub. I am willing to bet your sub is on par with your Thiels. But based on what you've said, and correct me if I'm wrong, your Thiels actually sound better now within the frequency range above because the amp can concentrate on the higher frequencies and let the sub do what it is supposed to. I have also read that if you feed the sub frequencies closer to 120, it will not sound as good over all as when fed frequencies below 40. But sounds like you are at a good balance point. Thanks again...

 

[JohnRice]

Mark, I have a good sub, but it isn't on the same level as the Thiels. There are a lot of variables, but your main speakers generally will not perform as well at their extreme as a good sub will at the same frequency. Plus, bass frequencies consume an enormous amount of power and if you are using ANY receiver, no matter what the specs are, it can be very easy to exhaust its power supply. Using a sub at a reasonable crossover reduces this quite a bit. Yes, as a general rule, crossing over as high as 120 Hz has drawbacks, but can still be the best solution of the main speakers are not capable of bass in that area. My general rule for a starting point to set the crossover is 1 octave above the speakers' -3dB point. So, that would be 60 Hz with yours. But try higher and see how it goes. There is a lot of stuff to calibrate when you are using a sub and it can take quite a while to get the best result. Placement of subs is also very tricky and no amount of tweeking will completely solve what better placement can.