170's mounted to front wall. Block rear ports?

[hardax]

I recently mounted my Ascend 170's to the wall on either side of my projection screen and the rear ports are now about 4" away from the wall.

My bass is a bit "boomy" and I wonder if blocking the rear ports would help tighten things up or make things sound worse?

I am using them with a HSU STF-3.

Any advice?

Thanks

[GaryB]

Don't block the ports without asking DaveF's opinion first. Some LF drivers are suitable for both ported and sealed enclosures, others are much better in one or the other. I suspect you're not likely to risk damage due to over-excursion by trying this, but better safe than sorry!

[davef]

Hi Hardax


I recently mounted my Ascend 170's to the wall on either side of my projection screen and the rear ports are now about 4" away from the wall. My bass is a bit "boomy" and I wonder if blocking the rear ports would help tighten things up or make things sound worse? I am using them with a HSU STF-3.
Thanks

The first step you need to take is to determine where the "boom" you hear is coming from... (what frequency approximately) I would recommend turning the subwoofer off completely and then listening to the same source.

If you have the CBM-170 and STF-3 properly integrated using an 80Hz crossover in your receiver, I strongly doubt the boom you hear is due to the clearance between the 170 and the wall behind it. The CBM-170 has a port tune of approximately 50Hz... Using an 80Hz crossover, very little information will be coming out of the rear port...

Please give me a call when you have a chance. It is easier to troubleshoot over the phone and I would be happy to spend the time with you.

[hardax]

Thanks for the advice guys.

Dave, tried turning off the sub completely and you are correct. The "boomyness" that I am hearing is coming from the sub and is not caused but the 170's. I need to find a better location for my sub I am guessing.

I remember reading that the rear ports of your speakers should be at least 6" away from a wall and am still wondering if I am causing any sound problems by having them just 4" (maybe even a little less than that).

I am crossed over at 80Hz.

Many on the AVS forum have suggested blocking the ports on my 170's but I am not sure what that would accomplish?

Thanks again all.


Hi Hardax



The first step you need to take is to determine where the "boom" you hear is coming from... (what frequency approximately) I would recommend turning the subwoofer off completely and then listening to the same source.

If you have the CBM-170 and STF-3 properly integrated using an 80Hz crossover in your receiver, I strongly doubt the boom you hear is due to the clearance between the 170 and the wall behind it. The CBM-170 has a port tune of approximately 50Hz... Using an 80Hz crossover, very little information will be coming out of the rear port...

Please give me a call when you have a chance. It is easier to troubleshoot over the phone and I would be happy to spend the time with you.

[curtis]

I think the recommended distance behind the port is 3" in the manual.

AVS members recommending the block the port? I must of missed that.

[Lou-the-dog]

Many on the AVS forum have suggested blocking the ports on my 170's but I am not sure what that would accomplish?.

I think some over there like to make this generic recomendation when someone complains of loose bass...not a necessary or recomended measure with Ascends. It sounds like the sub is your culprit so placement and/or equalization should solve your problems.

Randy

[Lee Bailey]

If you really want to tame your sub, you'll need a parametric equalizer like a BFD. You could then keep it where it is currently.

[hardax]

Thanks again everyone. I will not try blocking the ports.

Lee, i have heard of BFD but really haven't considered it so I don't know much about it.

I am under the impression that it is extreamely complicated to set up?

It does sound like an option for me as I am extreamely limited to where else I can move my sub.



If you really want to tame your sub, you'll need a parametric equalizer like a BFD. You could then keep it where it is currently.

[bikeman]

I am under the impression that it is extreamely complicated to set up?
It does sound like an option for me as I am extreamely limited to where else I can move my sub.
Setting up the BFD is more time consuming than complicated. There are some programs like:
http://homepage.ntlworld.com/john.mulcahy/roomeq/

This can make the process more automated but I haven't tried it. I'm still doing it by hand. If you need further assistance with setting up a BFD, let us know.

David

[dae3dae3]

The BFD isn't that bad as long as you follow some of the faq's out there. It will take 95% of your time to measure and then input the first filter. The rest of the filters will take the last 5%. Once you do one they are easy.

The free Room EQ wizard will let you try out filters and see what they will do before you input them. If you get a Midi cable and have a laptop it will even program the BFD for you.

Don't get too scared. You will spend one afternoon setting up the BFD and then you never touch it again unless you move the sub or change subs or something like that.

Check out this graph of what I was able to do. File is attached.

[chasw98]

I agree with Darren. You must get a Radio Shack SPL meter. (Check B&H photo for ~$35.00 shipped under brand name ATI). I bought my BFD off of ebay for $66.00. It took me a day and a half to get the setup running right with Room EQ Wizard, including MIDI. After letting REW set up the filters automatically through MIDI several times, I quit using it automatically. I was able to use 4 or 5 filters manually to get the same approximate response curve that you see Darren has posted. It works. At a bare minimum get a SPL meter to have some reference point.

Chuck