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Role of sub woofers?

I had begun thinking about changing out the KEF Reference 1s for floor standers, something like Wilson Sophias, Revel Ultima Studios, or the expensive KEF Reference 207/2s. Then I reset the crossover for a pair of Velodyne HGS-15s from 40 Hz to 80 Hz, and the sound stage size, sound stage depth, and sound stage detail improved so strikingly thoughts of changing anything vanished. I did redo the speaker setup extensively, including redoing all the SMS-1 bass manager connections, so I suspect the vast improvement was due to more than just adding 40 Hz to the range covered by the the subs — I must have fixed some previously unknown problem. Anyway, a setup that I thought was best for jazz and baroque now does large orchestrations convincingly with a sense of spaciousness I had previously imagined only floor standers could deliver. One detail I’ve noticed is that the power-on LEDs of the subs that were previously rarely activated are now usually lighted, suggesting the subs are playing a much more active role.

Well about not changing anything: I have a third HGS-15 I might install on the wall opposite the setup for a three sub distribution.

db
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james633
1,048 posts
 
Imo the best thing you can do for a system is use subs with a high pass crossover (like JL CR-1) to the mains. I wish more preamps had bass management in them. It could really cut down on the clutter. 
I have found most speakers cross over best at 60hz give or take. Not low passed but crossed over. If you are going to just low pass the subs they need to come in under the speakers. I like to be 1/2 octave  above the minimum motion of the mains bass driver if using a 24 dB slope.  
60z is good because a lot of bass drivers start to roll off around 60hz. 
m-db's avatar
m-db
997 posts
 
db, do you have the Velodyne SMS-1 Manual, Sweep Tone CD, calibrated microphone, and the Windows Setup Program loaded?

This is the Outlaw SMS-1 Manual which offers an alternately worded explanation of the Velodyne Manual which you may find helpful in explaining how to use the SMS-1. http://pdf.outlawaudio.com/outlaw/docs/sms1guide.pdf
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dbphd OP
1,631 posts
 
I have both SMS-1 manuals, several sweep tone CDs, calibrated microphone with stand, and a monitor for displaying the various videos generated by the SMS-1.  I prefer the Outlaw manual.  I actually have three SMS-1s, but use only one.  An Ayre KX-5 Twenty preamp connects to the input of the SMS-1.  I've tried a couple of high-pass crossovers between the KX-5 and VX-5 amp even though Charles Hansen discouraged it, but it turned out he was right; the sense of openness was compromised.

db


mijostyn's avatar
mijostyn
8,570 posts
 
@dbphd , subs are a very complicated, tricky issue. That sense of openness you like is being caused by the slight echo in the upper bass lower midrange occurring between your subs and the main speakers. With the subs set at 80 Hz there is a small amount that leaks through. A cross over is not a cliff, it is a slope. Many people like this. Adding high pass filters will always increase headroom and lower distortion more or less depending on the design of the main speakers. It will also decrease the amount of overlap and get rid of that "echo."  The higher you crossover the the greater the increase in headroom and the lower the distortion. I cross over at 125 Hz but my ESLs are "one way" and so benefit most from this. Whereas, in a two or three way speaker only the woofer's range is going to benefit from lower distortion. A high pass filter should always improve the sound.   
m-db's avatar
m-db
997 posts
 
db, mijostyn's terrific description may be adjusted out after another Auto EQ. Then by manually adjusting the Low Pass Xover Slope and Contour Frequency.

Velodyne's later Plus Optimization has a simple visual and audible drag and drop Q adjustment for individual bandwidth parametric filter frequency and level.

When used in conjunction with its discrete multi-band gain settings allow for a much higher crossover beginning with tone that closely matches the mains presentation from the crossover region on.


This replaces the hard crossover point used by most other equalization programs or basic settings.


You might give a thought to setting some of your presets with differing crossover and slope settings to help narrow down an optimum while your at the listening position. 


Once I tailored my crossover region it's saved to all the presets while the equalization after the region varies. #6 is a polarity reversal.

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