Some tip to create an
Excellent Listening Room!
Remember the law of acoustics and human hearing is this: the nearest room surface between your eardrums and the speakers dominates the frequency response. That's most often the surface of the floor. The sound you hear is 90% reflections according to researchers over the decades. The room and more importantly the surface of the flooring dominates the frequency response. Not the loudspeakers.
Carpeting in a high end listening room or home theater is a big "No-No".
The reason? Carpet fibers constantly bend, flex, and re-radiate the sound pressure from every loudspeaker and all noise in the room, totally fuzzing up the sound that reaches your eardrums. The only things moving/vibrating/resonating in a perfect listening environment are your ear drums and the speaker diaphragms. Carpeting is the worst thing you can do. Essentially the carpet fibers act like hundreds of little tweeters and midranges vibrating out of phase and time with the actual loudspeaker diaphragms. In the bass range, since carpeting is not glued down and worse typically contains padding underneath which is also almost never glued down, both the carpeting and the padding go diaphragmatic vibrating in syncopy with the bass and lower midrange frequencies/sound pressures put out by the loudspeakers. Distortion goes through the roof on measurements!
Actual in-room distortion measuring equipment which compares the in-room loudspeaker response versus the signals being sent into the power amplifiers can be as high as 40-50%. Remember power amplifiers are typically 1% THD max typically under .05% THD & IMD. The very high in room distortion figures are partially due to imperfect loudspeakers and cabling to a small degree, but mainly due to carpeting and padding (and walls flexing to a smaller degree) re-radiating the sound out of time and phase, distorting the music.
Instead it is best to install sound absorbing materials on the ceiling, corners and on the walls at the loudspeaker near-field reflection points. Tack up color coordinated open cell 2"-4" thick acoustic foam from www.foambymail.com
, it's inexpensive and works like a charm on the ceiling and side wall first reflection points based on experimentation with you listening and someone else holding up the foam sections on the wall to determine the most effective placement.
At the very least remove all carpeting & padding from underneath and around the loudspeakers. Install cemented granite floors or granite 12"-24" tiles and use floor spikes leveled out or better yet Herbies Audio Lab products work even better then spikes because they remain visco elastic converting standing wave resonance energy to heat efficiently, reducing "stored energy" within the loudspeaker cabinet, crossovers, and the drivers themselves. Energy must be constantly drained out of and away from the loudspeakers.
Rather then wood or carpet or tile in the main listening area and under furniture, it sounds better to install a one of the new vinyl wood look-alike floors glued down with "Green Glue" acoustic glue which is very efficient at converting resonance and vibration to heat so that it does not reach your ears. Wood & tile resonate too much in the mids and highs. Zero room resonance is the ideal. Wood and tile and granite exhibit a poor high resonance pattern. Home Depot carries a nice top of the line type of non-resonant wood look-alike flooring by TrafficMaster "ALLURE" @ $3.65 per square foot that is very non-resonant. It sounds best when glued down with "Green Glue" (available off eBay) which stays tacky and squishy and super sticky to prevent the floor from resonating. Truly huge improvement when glued down with Green Glue. Green Glue is pricey about $250 delivered for a 5 gallon bucket. Green Glue should also be employed between double layers of 5/8'-7/8" drywall/sheetrock. Sheetrock should be applied over the studs over special adhesive closed-cell rubber gasketing available from NORTON. Apply the gasket strips directly against all wall studs. The room should have double layered silver foil insulation on the studs and ceiling joists and all seams overlapping and taped tightly with silver tape. Keep wall studs on a 12" stud center-to-center in order to avoid the drywall from "pumping" under heavy bass/room loading conditions, massively distorting bass reproduction. All products are available through eBay: search terms include Green Glue, Norton acoustic, gasket tape, ARMA foil, E Shield foil, etc
Note on AC lines: AC power for high end electronics should always be dedicated and shielded and always be off the same exact "phase" 120v service. There are two 120v services in every panel, one sounds bad the other good and they are not labeled. Each 120v incoming phase from the utility company sounds very different, one good the other bad. One is a +120v the other a -120v which when combined the two form the 240v needed for such things as electric dryers, electric ovens, electric water heaters etc. You should install dedicated "Isolated Ground RFI/EMI shielded Romex" to the sources, amps, subs, and projector each separately using "Isolated Ground RFI/EMI shielded Romex". Shielded isolated ground Romex which works surprisingly well much better then the orange colored unshielded cryo'd 10ga Romex, night and day better on both picture and sound due to rejection of RFI & EMI that is all over every household from wireless telephones, digital alarm clocks, microwaves, cell phones, radio and TV stations, police/EMS radio, ions from sun, background RFI from Earth and Space, etc. The answer to signal integrity and State of the Art performance is rejection, dissipation and overall elimination of RFI and EMI in conjunction with the best electronic parts and wiring inside all of your components. It's the RFI and EMI that your components generate themselves within their own circuitry that matters most.
Having an RFI/EMI powerline filter only affords a tiny fraction maybe 5% of what our SE upgrades provide by ridding RFI & EMI inside your components where it matters most.