Many subs have irregular frequency response in the rooms they are used in.If the SUB doesn't have its' own amp,then you could try a "plate" amp with parametric EQ.Parts-Express has 500/1000W units with this feature.
Subwoofer Frequency Response question
I just started testing my frequency response with a Radio Shack SPL meter (digital). My subwoofer is a Paradigm PW-1100 (10 in) with Green Mountain Europa speakers. The room is small, 12 X 14 X 9. The frequency response is generally very good with bass response down to 25 Hz. My issue is I have a dropout of nearly 20 db starting at 45 hz through about 70 hz. I have not been able to change it by moving the sub or changing the settings (phase and crossover point). I also have the sub on an elevated platform of 1 1/4 inch MDF with spikes between sub and platform.
I am wondering if adding internal bracing and additional acoustic dampening material to the sub woofer would change the response characteristics in a positive way.
Any ideas would be appreciated.
I am wondering if adding internal bracing and additional acoustic dampening material to the sub woofer would change the response characteristics in a positive way.
Any ideas would be appreciated.
- ...
- 13 posts total
Drewhl: Are you taking readings in hz on your meter? I have a Radio Shack digital SPL Meter (cat No. 33-2055) but it only reads out in dB's and not HZ. How do you know your sub is dropping out 20dB between 45 and 70 hz? I've been looking for a digital meter that can read out in hz. Can you explain? Sorry if I sound naive. Thanks. |
Your going to need to get a better handle on whats going on, before you can attempt to fix the problems. If your going to try the spl meter route then you will need a good cd, or a computer with test tones on it. For free go here: http://www.realtraps.com/info.htm You can download the test tones and burn them, or use them direct from your computer (better, because you can loop them). These are better than most because they cover more range, one db at a time (you can read about them first). There are some other good tools at the site also...and plenty of good reading. I usually start with the main speakers only, and then I move to the subwoofer only. And then move on to some crossover settings, that I think will pull the two together, as one. Kind of a divide and conquer approach in the first two steps, or at least a better understanding of the problem. The "Virtual Minirator" download is another good tool for your computer. I suspect you need a lot of bass traps in that room, but hey...what room doesn't :-) Dave |
Thanks for all the suggestions. I am using the Rives CD with 1/3 octave tones calibrated for the RS Meter. I am going to check out the realtraps site. Using this, I was also able to find a wire vibrating inside the speaker at mid-range frequencies. A little Blu-tak and voila! No more vibration. PDN - Measure test tones with the meter in dB then graph the test tones and you will determine what your response is in a given frequency range. I took readings with and without the sub and with the subwoofer by itself. This really helped clarify what was going on (thanks Dave). I was clearly having phase cancellation. After tweaking the settings on the sub and taking readings at various settings, I was able to eliminate the dropout at 50 hz and get a fairly flat response. The exception is at 35 to 40 hz where I have about a 10 dB increase. This seems typical of many subs and may also be the room. Would this be eliminated by stuffing more material into the sub or external bass traps. |
A 10db peak is not uncommon at all, you could eq that down. Peaks are better than nulls, you can't eq a null up and out. Some subwoofers (they call them hometheater subwoofers), do indeed have built-in bass peak, I don't know anything about your sub though. At any rate...you could eq that out too. Dave |
- 13 posts total