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do I need to address low freq reverb/ decay?
Old 1 week ago
  #1
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do I need to address low freq reverb/ decay?

Hi there!

Hope all is well! Am trying to improve the in-room performance of the sounds systems in my room (bedroom). Would really appreciate the feedback of the folks in this group.

I have two similar 2.1 systems in the same room, one is a desktop setup and the other is a TV setup:
Each contains a:
• A pair of Eve Audio SC208 powered studio monitors (AMT tweeter with 8” woofer)- freq response -3dB @35Hz
• Martin Logan 1000W 12” sealed sub on an Auralex subdude
• Topping DX3 Pro DAC used for both setups

The only differences are as follows:
• The desktop setup has the speakers connected to isoacoustic stands on an hardwood desk. Appropriate ear height and equilateral triangle. I use Equalizer APO for EQ. The sub is behind the listening position but nearfield (not much farther than either speaker). The connection to the SUB is a via a wireless receiver. It introduces negligible latency vs. a wired connection.
• The TV setup has the speakers on adjustable-height floor stands and are connected to the sub via interconnect. It uses a Topping DX3 connected to a miniDSP 2x4HD for DSP/EQ (and DAC function). Theyre a few meters from the listening position so it’s not an equilateral triangle.

I have taken several measurements using a UMIK-1 calibrated mic and REW
I have 2 problems:
1. High reverb/decay at low frequency (~1 second decay times below 100Hz on desktop setup and ~0.7 seconds with the TV setup). My reverb/decay looks good above 100Hz.
2. Two 20-30dB nulls @ ~45Hz and ~85Hz in the TV setup. The frequency setup of the desktop setup actually looks great with some minor EQ.

I think the solution to #2 is to just add a second sub and smooth out the in-room frequency response. Thoughts?

My questions:
1. How much does reducing reverb/decay matter at low-frequencies? From my understanding, it’s hard to identify differences in decay times/reverb at low frequencies (100Hz and lower). Research papers suggest long decay times (well over 1 second) can’t be distinguished from shorter times at low frequencies. If that’s the case, what’s the use of using thick (very thick) bass traps to reduce low-freq reverb?
Research paper:
https://assets.ctfassets.net/4zjnzn0...a_valimaki.pdf

2. Is the problem re. decay times that the difference in decay times across the frequency range? My decay time above 100Hz is short (under 0.4 seconds) but does the low-end decay times being longer mean it makes the overall sound less coherent?
3. Can changing the subwoofer location help with decay times/reverb for the desktop setup?
4. Does using dual subs help with low-end decay times?
Old 1 week ago
  #2
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mirochandler's Avatar
Quote:
Originally Posted by ahmedmo1 View Post
From my understanding, it’s hard to identify differences in decay times/reverb at low frequencies (100Hz and lower).
No, it is easy. And more easy, if the decay times on higher frequencies are already short. A lot of beginners make that mistake. But you have to start in the lower frequ. with acoustic treatment because it needs more space.

Quote:
Originally Posted by ahmedmo1 View Post
Research papers suggest long decay times (well over 1 second) can’t be distinguished from shorter times at low frequencies.
Maybe that is an old perception. It is harder to set up for example a compressor for a kickdrum and want to hear the difference of a release time of 80 or 150ms when the room needs more then 1000ms to be nearly quiet.
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