I realize that this thread seems to be for owners of the USB Mic with HDMI connection but there are a lot of knowledgeable people here that I would very much appreciate their input, so I hope that my EMM-6 setup doesn’t exclude me from the thread.
I do have a room construction link below for a much more detailed overview of my room.
The biggest problems that I had with my room are:
1. The HVAC was too noisy and cooled the room far too fast.
2. No amount of mid-range EQ tweaking using Audyssey Pro seemed to satisfactorily fix the “hard” vocal upper range.
3. The LF decays were slightly worse than I had expected.HVAC
Please see my link below (page 2) for those interested in my HVAC solution and noise floor measurements. It’s not really relevant to this thread.ACOUSTICS
The room revised elevations are shown below:
Revised Room Elevations and First Reflections
Revised Room Elevations and First Reflections.pdf 776k .pdf file
The changes from the original design are summarized below:
•Added first point refection absorption for the height, left, center and right speakers to the ceiling and door area.
•Changed the absorption thickness on the left and right walls next to the speakers to an average of 5+”.
•Modified all the speaker grills to remove/reduce edge refraction issues.
•Added front sub isolators
Door, Wall & Speaker Absorbers
The room is loosely based upon a LEDE concept. I realize that it does not meet several criteria for such a room, in particular the Kicker delay. The original delay was designed to be just over 10mS and I wanted at least a 20dB level drop by 1mS extending to 10mS. I originally had the 10+mS delay but found I needed to move my MLP backwards by over 6”which caused the primary reflection from the rear QRD to move to 9.5mS. The good news was that after exhaustive testing this earlier arrival has absolutely no effect on the sound stage and its removal makes the room feel too dead.
The biggest issue by far was the over bright upper mid-range particularly on female vocals. The Genelecs are known for being a little bright but what I had was not fixable this with EQ via Audyssey Pro.
I need to point out that the original Audyssey XT32 Sub EQ and AVP XT32 EQ have never been changed during any tests; it just takes too long (WAF) to frequently run the full 11.1 tests and then Pro re-EQ on top of that.
What I eventually discovered was based mainly upon the ETC measurements. The primary reflections from the ceiling/walls and the non-linear reflections from the 1” fiber glass absorption next to the left and right speakers were significantly affecting the frequency response, or at least what I heard, which Audyssey seemed to either ignore or incorrectly try to fix. I also had two primary reflections from the door area from the Center and RHS speakers that needed to be removed.
Once this absorption was installed there was a dramatic improvement to what was already a respectable sound stage and the upper mid-range improved significantly but was still too strident. I specifically did not use diffusion as I could not predict what it would do and wanted to maintain the front of the room as being dead with minimal reflections; so as I have “gobs” of SPL and headroom from the 1038 Genelecs, driving them a dB or two harder is of no consequence.
As can be seen from the latest ETC there is still a single very strong primary reflection around 1.2mS with a lot of “clutter” around it. This L/R symmetrical reflection, believe it or not, is from my suspended wooden floor, which is covered with 5/16” felt and 5/16” carpet. I have to assume that as these products are both made from synthetic fiber that they have very little acoustic absorption and will now have to be replaced with pure wool ½” acoustic felt underlay and ½” wool looped carpet; I have samples on the way to test.
The lack of absorption was confirmed by placing a small piece of 1” thick fiberglass batting at the primary floor reflection point and as can be seen below…the reflection is greatly improved.
Latest ETC with Floor Absorber
I can see no way for me to modify the room layout in any way to remove these floor reflections so any advice here to help me get rid of them would be gratefully received. Short of replacing the carpet or adding a REALLY thick rug across the front of my room!
Once I reduced the level of these floor L/R reflections I again noted a further slight reduction in the upper mid-range vocal “hardness” to an acceptable point. So much for Audyssey dealing with the impulse time domain, maybe it isn’t supposed to but their site seems to indicate that it does, not too sure how though.
The graphs below show the rooms’ current overall response.
Current Frequency Response
I originally introduced the “suck out” between 500Hz and 3.5 KHz using Pro in order to compensate for the overly bright response, it also includes the Audyssey crossover correction. I have no idea where the 322Hz dip came from but once the rear ceiling 2D Skyline diffusers are mounted I will re-run the full Audyssey EQ and re-publish.
The LF response 15Hz to 300Hz is flat enough for me and I have no desire to improve it. However I hope that when I re-run Audyssey and remove my Pro EQ the remainder of the response will match it.
Current Waterfall 1 – 15-20Khz (1/6 octave smoothing)
Current Waterfall 2 – 15-200Hz (1/48 octave smoothing)
I do not usually use data much below 60dB as the mic pre-amp LF noise floor is too high there (see my link), and below 32Hz most people’s threshold of hearing cannot detect that level. I will try to tame the response slightly at 27 Hz using Pro, hopefully that will pull the 27Hz decay back a little to.
The Spectrogam seems to confirm the waterfall showing a maximum decay time of 450 mS for a 40dB decay for frequencies below 40Hz. There are no irregular decay patterns above this frequency. If the group delay of the subs, shown below, is taken into account then most of the LF decay relative to its peak is within 400mS.
Current Group Delay
Whilst I am basically happy with the LF response in terms of extension and clarity etc., I would still like to improve the decay below 40Hz if at all possible. I have therefore just updated the room to handle a pair of rear subs (either SVS SB12-NSD or PB-1000 as I have a space restriction) in the hope that if I reduce/cancel the level of the primary length mode I may see an improvement in this bottom end decay. However if this decay is strictly limited by the amount of LF absorption in the room (of which I can add no more due to lack of space) then I may see either no improvement or it may get worse depending upon how the additional subs interact with the existing rooms acoustics. Unfortunately the sub locations are really fixed per the attached room layout. I will update the thread once I get them installed and measured.
Comments on any of my graphs/room would be gratefully received and as to whether or not the addition of these additional subs will be of ANY acoustic value to the reduction of the LF decay, ignoring the obvious benefits to LF headroom and possibly flatter LF response, neither of which I am looking for.
If any additional graphs etc. are needed to help with any comments/analysis please let me know.
One final comment; what is very noticeable regarding the “hard” upper vocal register is that it very rarely reveals itself on high bit rate stereo or multi-channel DVDA, SACD or Blu Ray recordings but is very prevalent on many stereo 16 bit 44.1K CD’s. It does not matter whether I am using analog, HDMI or DL3/4 for the connection. It is almost as if during the mastering process they are compressing and pushing forward the upper mid-range. It does however become less noticable on these CD’s if I disable Audyssey but then the room doesn’t sound as pleasing.