Description

Studio style flush (soffit) speaker mounting - speakers are mounted into a wall with drivers flush with wall surface. Note that this is not simply an HT cabinet - all of this was custom built with extra thick MDF and heavily braced to eliminate vibration. Speaker is decoupled from framing with rubber pads and surrounded with 8 inches of pink acoustic fibreglass on all sides.

The bookshelves above are intended to absorb some lower frequencies, as is the log fire place which is 8 feet behind the listening position. More acoustic absorption is achieved by four massive GIK Tri-Traps. The audio signal that goes to the subwoofer is treated separately by a PEQ with specific notch filters to eliminate LF room modes.

The down firing ATC 15" subwoofer is driven by its on board 1000 Watt amp (positioned to the left of the main speakers). Active ATC main speakers have three separate (Class A to two thirds power) amps each for each driver: 200 Watts amp to each 12" woofer, separate 100 Watts amp to each mid range and separate 50 Watts amp to each tweeter.

Five giant Sony Megachangers are controlled at the touch of the keyboard trackball, all from the listening chair (software controlled from the Mac Mini). Each of these five Megachangers TOSLINK output is connected to a Benchmark DAC1. The DAC1 corrects for the jittery TOSLINK outputs and produces a sound quality way beyond the modest price of the combination.

All in all I try to combine convenience with a pretty high end sound.

Doug Sax of Sheffield Labs fame uses soffit mounted active ATC speakers driven by Benchmark DAC1's in his studio. I figure what is good enough for Doug Sax's "golden ears" is certainly good enough for my "tin ears"! Besides, as so much music is mastered by Doug it is nice to hear it as close as possible to the way he does when mastering.
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Components Toggle details

    • Waterfall in room Bass Response Plot
    Flat response, no significant resonance and smooth even decay down to 20 Hz.
    • In room Frequency Response Bass Plot
    Blue plot is before EQ correction to the sub. Red is the corrected in room response. Speakers are run full range flat with no EQ or tone control.
    • T30 Room Reverb RT60 Decay Time
    This shows the reverb decay time it takes for sound to decay to -60 db. A value of 0.4 is considered ideal for my large 7000 cu feet room. It is acceptable for reverb decay time to rise in the extreme LF provided it stays below 1.1 (for this size room). It is important that the room is balanced with no spikes in reverb time. Room reverb is much more important than a perfectly flat frequency response.
    • ATC SCM-100A
    Active Speakers 12" Woofer, 3" dome mid,1" tweet, separate 275W,100W, 50W amps
    • ATC SCM-0.1/15
    Active sub 15" Woofer driven by 1000W amp
    • ATC SCM-20SL
    Surrounds - Passive ATC 75mm dome mid range grafted on ATC 150mm woofer with 1 inch dome tweeter(vifa). You can see them on top of fireplace, which is on rear wall (facing front speakers)
    • Benchmark DAC1
    Each of my five CDP Megachangers TOSLINK is fed to a Benchmark DAC1 which does the D to A conversion after eliminating the TOSLINK Jitter
    • Sony CDP-CX350 (Five of them)
    CD Mega Changer 300 dics - controlled by Sony A1 through Slink-e and Apple Mac Mini
    • Anthem AVM-20
    Surround Processor
    • Bryston 4B-ST
    Drives L and R surrounds
    • GIK Acoustics (Four of them) Tri-Trap
    Triangular Bass Trap, 4 foot, 17x17x24 inch crossection, 3 Units on back wall and one unit is on the front wall.
    • Fireplace but actually stealthy Bass Trap & RPG Skyline diffuser
    18" Logs stacked perpendicular to the rear wall in random fashion. Bark is left on the logs to help sound absorbing surfaces between logs. Logs vary in length to give a skyline diffuser surface.
    • Beringer DSP1124P
    Parametric EQ used on Sub Woofer for Room Modal Response control.
    • Macintosh G4 Mini Titletrack Jukebox
    I am not generally a tweaker. EQ adjustments for room modes on the sub and speaker soffit is all I do. I use my Macintosh G4 and Titletrack Jukebox software to control everything: browse/find music and set playlists, stage CD's to changers for continuous cued music playback from five Sony mega CD Changers, or iTunes. Mac mini also controls all equipment settings (RS232 to infra-red adapters).
    • Sony BD S300
    Blu-ray Player
    • American Power Conversion AV H15
    1.5 Kva
    • RAW RESPONSE LEFT SPEAKER - NO SUB
    Raw unfiltered response - no subwoofer

Comments 105

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Hi Shadorne and Mjcmt, Shadorne thanks for the new freq response graph. I will respond as soon as I can about some thoughts etc. At this point I am working my new job and my old one along with having my semi-annual Italian bike party on Oct 3rd with 100-120 people in attendance at my house...very busy.

Bob

acoustat6

Hi Shadorne and Mjmct, thanks for the post Shadorne but the waterfall plot that you show will not help Mjmct see the effect of comb filtering. Shadorne did you do the Fuzzmeasure yourself? Or did someone do it for you?

Also I am not really sure that Fuzzmeasure has enough resolution to show these effects. If you are unable to do this I have a few good graphs that I have done using REW that show the effects well. In particular are some graphs with before and after with bass traps added.

Bob

acoustat6

Hi Mjcmt and Shadorne, Perhaps Shadorne would be so kind to post a graph of his in room freq response with no smoothing supplied. It would help Mjcmt to see the effect of smoothing and also show him what typical comb filtering looks like. Allthough, as Shadornes room has some acoustic treatment, it would not be as dramatic as a more typical untreated room which would exhibit severe comb filtering.

Bob

acoustat6

Hi Mjcmt, it is not as smooth as it looks. With 1/3rd octave smoothing applied it makes the graph appear much better than it is, as the comb filtering effect is removed in the higher freq and the peaks and nulls are smoothed in the lower freq..

Bob

acoustat6