Polk CS2 Center Channel "Boxy Boom" fix/aid/tweak
Cybershaman
Posts: 44
I don't know about anybody else but I have always noticed that my CS2 center speaker sounded kind of, well, I don't know how to exactly put this but, "boxy". While male voices don't really dip very deep, I suspected that maybe there was some sort of harmonic or standing wave issue going on. While I don't have the speaker butted right up against the wall (it's about 6 inches out) I generally don't like to pull it out too far so that it "presents" itself obtrusively. It wasn't long after I got the Velodyne SMS-1 that, in typical Cyber fashion, I decided to use it for something that it wasn't really intended for...
Let me just say that the SMS-1 is probably the coolest piece of equipment that I've ever owned. I feel bad recommending it because, let me tell ya, convincing people that they need to get a $500 subwoofer tweaker is a hard sell. Velodyne must have had one heck of a vocal community for them to even consider marketing the thing. ANYWAY, since the unit's on-screen frequency response graph goes up to 200Hz, I thought that, through some clever switching trickery, I would try to plot its low end response. Sure enough, there was a big ol' spike right around 100-125Hz. Well now, that was all fine and dandy but at first I figured that there was nothing I could do about it except pull it out well away from the wall. (which I did and it helped) But then it hit me: the things bass reflex port was pointing right at the wall! So it was off to my bedroom to find the perfect...sock! Yep, I ended up balling up a thin, polyester, calf-length tube sock and loosely stuffing it in the port. After that, I ran the SMS-1 frequency sweep again and, presto!, gone was the spike! And how does it sound now? MUCH better! Gone is that boxy sound that reminded me that all of the dialog in a movie was coming from, well, a box!
So there you have it: an easy, low tech solution to a minor problem. And THAT, my friends, is one heck of an easy sell...
PS: For what it's worth, I have my receiver crossing the center channel over to the sub at 60Hz. I probably could have upped the XO frequency but I have this quirk about making my speakers go as low as they can. I know it would probably be fine (and easier!) to raise the XO frequency but this is just my personal preference.
Let me just say that the SMS-1 is probably the coolest piece of equipment that I've ever owned. I feel bad recommending it because, let me tell ya, convincing people that they need to get a $500 subwoofer tweaker is a hard sell. Velodyne must have had one heck of a vocal community for them to even consider marketing the thing. ANYWAY, since the unit's on-screen frequency response graph goes up to 200Hz, I thought that, through some clever switching trickery, I would try to plot its low end response. Sure enough, there was a big ol' spike right around 100-125Hz. Well now, that was all fine and dandy but at first I figured that there was nothing I could do about it except pull it out well away from the wall. (which I did and it helped) But then it hit me: the things bass reflex port was pointing right at the wall! So it was off to my bedroom to find the perfect...sock! Yep, I ended up balling up a thin, polyester, calf-length tube sock and loosely stuffing it in the port. After that, I ran the SMS-1 frequency sweep again and, presto!, gone was the spike! And how does it sound now? MUCH better! Gone is that boxy sound that reminded me that all of the dialog in a movie was coming from, well, a box!
So there you have it: an easy, low tech solution to a minor problem. And THAT, my friends, is one heck of an easy sell...
PS: For what it's worth, I have my receiver crossing the center channel over to the sub at 60Hz. I probably could have upped the XO frequency but I have this quirk about making my speakers go as low as they can. I know it would probably be fine (and easier!) to raise the XO frequency but this is just my personal preference.
Post edited by Cybershaman on
Comments
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I run that same center. I think room boundary effects are more likely the cause of such spikes. Mine is pretty much away from walls and other surfaces, sounds fine (of course, as you know male voices are one of the most difficult things for "any" speaker to reproduce "faithfully"). I also cross over at 60hz L/R/C but at 80hz for surrounds. I found setting the CS2 to 60hz made a significant difference in its performance.
Socks? Well, I have heard of stuffing ports before and have the foam plugs in my Energy RC-10s, mostly because they're rear ported and the only space I have for them is in a bookshelf unit (so it's sort of necessary there). Since they are a bass reflex speaker, I do lose a substantial amount of the low end with that set up!
cnhCurrently orbiting Bowie's Blackstar.!
Polk Lsi-7s, Def Tech 8" sub, HK 3490, HK HD 990 (CDP/DAC), AKG Q701s
[sig. changed on a monthly basis as I rotate in and out of my stash] -
I have a CS2 Series II from Newegg and I feel I need something better to go with my 2.3tls.
Or maybe mod it for better performance.
I wonder what would happen if I put a couple of spare MW6510 in it?POLK SDA 2.3 TLS BOUGHT NEW IN 1990, Gimpod/Sonic Caps/Mills RDO-198
POLK CSI-A6 POLK MONITOR 70'S ONKYO TX NR-808 SONY CDP-333ES
PIONEER PL-510A SONY BDP S5100
POLK SDA 1C BOUGHT USED 2011,Gimpod/Sonic Caps/Mills RDO-194
ONKYO HT RC-360 SONY BDP S590 TECHNICS SL BD-1 -
cnh: That's awesome that some manufacturers actually include port plugs. That could really help people in tight situations! So, room boundary effects, eh? That's probably it since I have such a limited space to work with. Take a look-see:
PolkieMan: So, you think by putting in those woofs, which, if I'm not mistaken, are identical to those in your 2.3tls's, will match your CS2 better tonally with your mains? You know me (or it should be becoming obvious...): give it a shot! This thread might give you and indication of what you might be up against: http://www.polkaudio.com/forums/showthread.php?50111-Difference-between-MW-6510-and-MW-6503-Drivers And if those are mint or fairly new replacements just remember the break-in period!
