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Need help with room

I currently obtained a SPL meter and Rives test CD to try and diagnose why my system is fatiguing in the highs and lacks in the mid bass. When I performed the frequency analysis I noticed that I have a rather steep decline in decibels below 400 hz bottoming out at 125 hz and then rising a little to 100 hz then back down. On the other end I have a sharp decline above 6300 hz. The total swing in db from top to bottom is as much as 30 db btw. 50hz and 16k hz. I would like to smooth out the frequency response and have tried moving the speakers, but it mainly just moved the lowest point a few hz without really affecting the response more than a few db and I need a lot more. I also tried different interconnects with minimal success. I tried removing my home made acoustic panels that did change things, but not to the effect needed and panels will not compensate for my base suck out if that is what I have. I am curious about my source because it does seem to lack in the lower end when compared to other sources, but I would be supposed if they could be that different. If anyone has any ideas I would greatly appreciate it.
Thanks, David

Room is 10' x 11' with 8' ceilings. Speakers are set out on golden ratio from front and sidewalls. One large window with metal blinds and thin curtain on front wall.
Parasound A23/P3
Denon 3800 (source)
Audioquest cheetah and jaguar interconnects
Alpha core Python MI2 speaker cables
dhel
11 responses Add your response
reubent
7,005 posts
 
You list your electronics, but I didn't see a mention of the speakers you are using. Since it is your speaker/room interaction that is likely the issue, it might be helpful to know what speakers.

TIC
shadorne's avatar
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shadorne
7,477 posts
 
Are you using single frequency tones or warbled test tones? Single frequency tones can give some deep spikes/nulls which I would tend to ignore if they are very sharp....30 db swing from peak to trough in your size room is not surprising. Check out what Ethan Winer's or Realtraps website says about typical room response...it is a real eye opener....don't worry you are not alone in having discovered a far from flat room response.

The dip between 100 Hz and 400 Hz is very worrying if it is a continuous and deep trough as is the decline above 6300 Hz - unless you are talking only a few db average drop (say less than 6 db from average). Although you will always have peaks and troughs due to the room modal response, which in your case will be quite obtrusive (small and close to a cube in shape), you should aim for a broadly even response when taking an average....a little bass heavy and a little roll off in the treble seems to be what most people enjoy most.

Room treatments can help and so can a PEQ like the one made by Behringer... but your room may pose a challenge which you can only expect to mitigate.
dhel OP
40 posts
 
Thanks, I forgot to put that in. The speakers are Boston Acoustic VRM 80's. http://www.bostonacoustics.com/home_product.aspx?product_id=189
Recommended Amplifier Power
50-250 watts

Nominal Impedance
8 ohms

Frequency Response (3dB)
42Hz-20kHz

Bass Unit
Dual 5¼ (135mm) DCD copolymer

Crossover Frequency
2,500Hz

Sensitivity (1 watt (2.83v) at 1m)
90dB

Tweeter
1" (25mm) black anodized aluminum dome with AMD™

Weight
58 lbs (26.0kg)
dhel OP
40 posts
 
The test tones are single frequency tones. While trying to figure out what was happening I looked at the Rives audio instructions and realized that I have the SPL meter on an 'a' weighted and it is supposed to be 'c' weighted. This made a huge difference as the differences in that the frequencies are only 13 db difference from the highest peak to lowest trough across 40 - 12.5k hz. I now show a small bass boost as I thought should be in my room. I am able to correct this. Now can I make the highs a little less fatiguing? I will try some absorptive panes at the first reflection points and behind my head instead of the combo diffusion/absorptive ones I made.
Thanks Shadorne, your response indirectly sent me to the info I needed and the RealTraps web page is also helpful.
dhel OP
40 posts
 
Bad quick math the difference is now 23 db in audible range. I see my bass node now and I can correct that, but I have a narrow +10 db spike at 630 hz that I am not sure how to mitigate. Any ideas? Also, are absorptive panels at the first reflection point likely to smooth out the frequency response above 200 hz?
mrtennis
3,295 posts
 
it is your perception of the sound of your stereo system which is important.

i reviewed audioquest cables and it is possible that replacing them with other cables may partially solve your problem. what cable you ask ?? try dcaa interconnects--all copper. you might consider trying another amp and preamp and also some ac cords, to see what affect such changes have on the sound and whether you prefer the sound with other components. the room may need treatment.

a further test is to use a high quality spectral analyzer at the listening position, using white or pink noise.
dhel OP
40 posts
 
Thank you for your response, I may consider going back to all copper interconnects to help tame some of the high frequencies as they can be fatiguing. The question around smoothing out the response is mostly a curiosity; I am not too worried about it, but I would like to hear what audible difference a flatter feq. response would have. You also mentioned an interconnect, but I cannot identify or find info on it, dcaa?
Thanks
montytx
138 posts
 
With such a small space, it is very easy to overload the room at too high SPLs. I would consider setting your meter at 0 at 80db and 1Khz. Also, the distance from your driver to the surrounding boundaries will have the most significant sonic effects. For example, if your drivers are 30" from the floor, placing them 30" from the front and side walls will reenforce the upper bass...the listening position being near the rear wall will only add to the upper bass as well.

If you are able to place your speakers along the wide wall, about 6 ft. apart and 2 feet from the front wall to the front of the speaker, you should help your upper bass response become more flat.

The upper frequencies will be very difficult to tame in such a near-field listening situation. I would attempt to fire my drivers as near straight ahead as possible without losing the center image.

When dealing with small listening rooms and near-field conditions, the first reflections are much less of an issue as the time delay in reaching your ears is insignificant. The brain simply can't process reflections that are so close to the arrival time of the original sound. However, high spls will really muddy up the sound as the room quickly becomes a standing wave nightmare.
ngjockey
1,042 posts
 
Forget that the electronics could be causing such big, actually huge, swings. It's either the speakers or the room. According to the numbers you came up with, the best solution might be the DEQX. Google it.
mrtennis
3,295 posts
 
hi dhel:

you can find my review of the cable on audiophilia.com .

also you can visit the web site dccaaudio.com .
shadorne's avatar
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shadorne
7,477 posts
 
A narrow spike at 630 Hz may be room related....try moving the SPL meter by 1 foot and see if the spike disappears. If it does then you may want to try acoustic treatments as an EQ will not solve that problem except at that exact listening position....and moving speakers or listening position around may simply move the null or spike to a slightly different frequency. (bear in mind your ears are about 6 inches apart and the wavelength of 630 Hz is a couple of feet)
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