November 2006 has seen the start of building a dedicated 2-channel listening room (a.k.a. "the man cave"). For the interest and benefit of others wishing to do likewise, I will try and relay details of the event that is expected to take 4-6weeks to complete.
* DESIGN
It all starts with a piece of paper and creative thinking of an audio designer which I found locally. Measurements were taken, consideration was given to room layout and planned speaker firing position. In my case I had two concrete block support pillars in the basement room and a lowish hanging support bean that sits atop the pillars. A structural engineer was called in to see about moving the posts and yes anything is possible with enough money . . . but the beams would stay put but be replaced by smaller footprint jack posts.
* ACOUSTICS:
The soundproofing would consist of Roxul acoustic and thermal insulation in the ceiling followed by Sonopan and 5/8" drywall to contain the sound. Special isolation clips for wall decoupling are used to isolate and 'float' the walls while rubber gasgets go between the concrete floor and wooden 2"*4" framing. J-molding, accoustic taping, 1/4" gasket for the ceiling/wall connection, air duct dampening material, insulated flex duct, external door with weather stripping were all used too.
* ELECTRICAL:
Four dedicated circuits will be installed: (i)a planned subwoofer on a 20 amp, 12 gauge Romex wired circuit, (ii) analog will also have a 20 amp, 12 gauge wire (in the event that my current 6watt/ch. amp gets replaced with a behemoth amp, (iii)digital will be a 15 amp, 14 gauge wired circuit, and (iv) a misc circuit for lights etc will also be 15 amp, 14 gauge. Isolated grounds will be created in the breaker box and plastic not metal recepticle boxes will be used to ensure only 1 end of the circuit is grounded (grounding both ends will cause the wire to act like an antenna!).
Planned future purchases include:
* Apple Mac Mini with silent hard drive and external RAID 1 disc storage for musical files
* Metric Halo LIO-8 Pro DAC
* Parametric EQ within the Metric Halo to tame the lowest bass mode peaks
I hired a small firm to design a dedicated music room in my unfinished basement which was no small feat. A contractor was hired to build it to spec and it was finished in January 2007.
Hemi-Cylindrical Diffuser / Bass Trap for Front Wall
A DIY hemi-cylindrical (poly) diffuser that doubles as a bass trap having OC701 fiberglass within its cavity. It's a 160degree arc from a 48" diameter Sonotube with red oak veneer on the exterior. The hard exterior diffuses mid/high frequencies in about a 110degree arc. With a total thickness of 30 inches, the hemi will absorb down to about 65Hz [1130/((30*7)/12)=64.6]
Front Wall Corner Bass Traps
A pair of DIY hemi-cylindrical (poly) diffuers that double as bass traps are in each corner. Eash is a 100 degree arc from a 48" diameter Sonotube with OC701 fiberglass in its cavity. They're covered with black speaker cloth to visually dissapear into the black coloured front wall. The total depth is 39" (27" radius + 12" air space) which absorbs down to about 49Hz. All hemi-diffusers can be pulled away from the wall to whatever depth is needed so as to tailor the low-end absorption.
Side Wall Reflecting Panels DIY
I built 3 reflecting baffles for each side wall. They are 3/4inches thick and run about 12feet long. Each baffle can be opened to any angle between 0 - 90 degrees. Right now the bottom baffle is open 30 degrees so that ear-level reflections are sent upwards to the ceiling diffusers, whereas the middle and top baffles are both open 20 degrees. The bottom baffle has a pair of GIK D1 QRD-like diffusers at each side wall's first two reflection points to help widen the apparent sound source width.
Skyline Diffuser for Rear Side Wall Treatment
A DIY Skyline diffuser for the rear right side wall. Uses 8 different cell depths in 1.5" increments with a maximum cell depth of 10.5". Being conservative, 10.5" is 50% of a 645Hz frequency which it will very effectively diffuse down to and likey another 0.5-1 octave lower. * Prime Number used = 547 * Primitive Root = 2 * 26 Columns * 21 Rows * 501 individual blocks of wood!
Hemi-Cylindrical Diffuser/Bass Trap for Rear Wall
Another two DIY Hemi-Cylindrical (poly) diffusers - one per back wall corner - to diffuse mid/high frequencies and absorb low frequencies as its interior is stuffed with OC701 fiberglass. Dynamat Xtreme (for car doors) was put on the hemi's inside to help reduce resonances and add stiffness. It's a 130 degree arc from a 48" diameter Sonotube.
GIK D1 QRD-like Diffusers for rear wall
6 are placed on the back wall (3 columns of 2) in front of 3 GIK Monster bass staps.
GIK Acoustics Monster Bass Traps for rear wall
3 total: Used on the back wall.
RPG Skyline (HP) Diffusers for Ceiling Treatment
9 Total: from speaker plane forward to listening chair.
RPG Skyline (LP) Diffusers for Ceiling Treatment
3 in Total: used on the dropped part of the ceiling between the front of the left speaker and the listening chair.
George Stantscheff Lightspeed Passive Attenuator
Passive attenuator that uses the special LDR (light dependant resistor) which has the ability to change it's resistance according to how much light LED (light emitting diode) is shone on it, hence it can control the volume without any mechanical contacts needed in the signal path. www.lightspeedattenuator.com
Art Audio PX-25
Fantastic sounding and very powerful despite being a 6 watt/ch. SET amp. With the KR Audio PX25 tubes and Sophia Electric 274B tubes and NOS input tubes.
FAB Audio Model 1
A 2.5 way with 1" tweeter and twin 10" drivers. High efficiency speakers (97dB).
Rythmik Audio F15
Two servo controlled subs each with a 15" driver and 370watts Class A/B each sub. Wonderfully musical.
Foundation Research LC-1
This is a bi-directional line conditioner filter and Cardas power cord all in one for the Audio Aero CD player.
TG Audio Lab HSR high purity silver interconnect
1.5 meter shielded
TG Audio Lab Speaker wire - silver
8 foot with spade ends
Audience PowerChord (4 foot)
4 foot power cord for Art Audio PX25 amp.
Dayton Audio OmniMic
Precision audio measurement system.
Sennheiser HD-600
headphones
StudioTech Component Cabinet U-22T
A rosewood cabinet with ventilation slots on the side, six shelves, cool looking doors and great WAF.
Wattgate 381 Ag AC Duplex Outlet
Audiophile grade AC repectacle. I bought two Wattgate 381's to be used on dedicated digital and analog circuits.
System edited: Just bought, and am eagerly awaiting, the receipt of a Lightspeed (passive) Attenuator by Georgehifi in Australia. It'll connect directly to the Art Audio PX25 amp. Hope it sounds good . . .
Kevinzoe...You have a most interesting music room to enjoy! I wish I could do something like a dedicated listening room,but would need to put an addition on the house! (a definite NO-GO with the wifey)
I also live in a historic preservation area here in Louisville (KY) and would need to get all kinds of permits and design approvals,etc. Way too many hoops to jump through,imo.
Hope you are enjoying your music and thanks for your efforts that give hope to those who wish they too could have a permanent and dedicated home to further their musical enjoyment.
System edited: Added descriptions of the front wall centre hemi-cylindrical diffuser (that doubles as a bass trap) and the pair of front wall corner bass traps that also double as a diffuser.
System edited: Added new pictures to reflect the work on building 3 more hemi-cylindrical diffusers for the front wall, They all double as bass traps due to their interiors holding OC 701 fiberglass. The front wall corners are 100 degree arcs while the red oak mid-wall is a 160 degree arc. They all got their start as Sonotubes (for concrete pouring) but had to be cut down to length and right arc degree size to fill the appropriate space. Also wrapped OC 701 fiberglass in plastic and stuffed the interior with it to act as add'l bass trapping. With the addition of the hemi's to the front wall, I took down the 8 GIK D1s and painted them the wall colour and hung them on the front part of the side walls. The immediate sonic impact was a deepening and widening of the sound stage. Lastly, I put some bass trapping on the floor by the mid-wall point of the back wall. It consists of 2 GIK Monsters and 4 GIK 242's all pushed together. They have an 13.5" air space between it and the wall and extends into the room 27" so it catches the 1/4 wavelength of 250Hz to 125Hz. The room and sound have seen a dramatic improvement over the bare walls before hand. I welcome your comments.I
System edited: Added new pictures. Made note of the new hemi-cylindrical diffusers I made for the side walls and the bass traps that are the 'boxes' they sit on.
Shadorne - thanks for your kind words. Like your "fireplace RPG-like diffuser" I too have taken an active interest in how the room affects the sound which I've been studying for a year or so now. Due to a noticable slap echo between the side walls between the speakers and listening chair I will embark on yet another pair of DIY Skylines that will be 14" max cell depth!! You can't buy that from RPG!
Soundgasm - thanks for your thoughtful comments too. A DIY Skyline can be tedious but the finished product really does look like a piece art. If you wish to try your hand at it email me and I'll send you a write up that documents each step of the way that I put together. And yes, each 4ft square panel on the back wall likely was 150lbs and took two of us to position onto a temporary shelf in order to fasten the 3" decking screws.
I'm not qualified to comment on the either your tech or design, but have to jump in here to say that your commitment and workmanship is really inspiring. That's a whole lot of love there.
Hi Spencer - nice to hear from you again in nearly 2yrs. Yes, the room is coming along, albiet slowly. The GIK gear really kick-started the acoustical treatment process and it's evolved into a series of DIY Skyline diffusion projects for key areas of the room. With the addition of more diffusers the sound gets better and better by reducing the room interactions that interfere with the direct sound. I was amazed at how much mid-high frequencies were absorbed with a low pile carpet. Combine this with the fact that the bass traps don't stop working at 500Hz so cummulatively they also contribute to upper frequency absorption and it's easy to get to a "dead sounding" room quickly. This is why I've opted to use so much diffusion on front, back and side walls and ceiling. The Skylines look very cool and are labours of love, plus I have so much control over the frequency range I want it to operate on and I can use whatever prime number that most closely aligns with the desired dimension of coverage needed.
It's been an interesting journey trying to sort out the conflicting advice offered by manufacturers (RealTraps/GIK) vs audio designers (Rives) vs acoustical scientists (Toole/Oliver).
Glad to see that you've really jumped in regarding treating your room. You have clearly learned what many refuse to believe; that it makes a huge difference. Nice work,dude! Cheers, Spencer
System edited: Adjusted the low frequency limits that my DIY Skyline diffusers work to. The original theory of Schroeder diffusers (written by Schroeder himself) gave the "design wavelength" of such a diffuser as just under 1/2 the depth of the deepest well. So my 10.5" deep diffuser has a design wavelength of just under 21 inches, which corresponds to a frequency of about 646 Hz [1130/((10.5*2)/12)]. Schroeder also noted that diffusion started (to some degree) at about 1/2 octave below the design frequency.
System edited: Just finished building another DIY Skyline 2-D diffusor for the rear part of the right side wall beneath a small window. Used a prime number of 547, primitive root=2, 26 columns by 21 rows and works between 622-4500Hz.
System edited: decided to add the 2 dimensional Sklyine diffusion to the list of acoustic treatments. If anyone wants to know how to build a DIY Skyline diffuser, email me and I'd be glad to share.
Hi Pat - sorry no pics yet as I'm waiting until the finished product is available before posting. As far as 'before' pics are concerned, just picture 4 bare walls and a white short-pile carpet on the floor and that was the starting point . . . I'll invite you over after the side walls are done, if you're interested in making the schlep out to the 'Shwa east of TO.
Kevin Thanks for sharing that with us Any pics before and after on the room and treatment adjustments.. I would love to see them when they are available Cheers Pat
System edited: After doing some research on small room acoustics and speaking with small room acoustic expert Dr Earl Geddes, I've rearranged some of the treatments I have. In general, there can't be enough bass absorption behind the speakers (front wall and front of the side walls) so I moved a GIK Monster bass trap from each side wall right by each speaker for SBIR duty to the centre of the front wall for the floor/lower wall corner. This improved on the 80Hz peak I have. I also put the four 242's on the front wall covering a 8'*4' space which deepened the soundstage. Toeing in the speakers quite a bit helps reduce the first angle side wall problem but with bare side walls slap echo is still a problem. SO, I will be venturing to build a DIY 2-D Skyline diffusers for the side walls, about 12 linear feet on each side wall - yikes that's a whole lot of little wooden studs. With 10'*4' of 1-D diffusion on the back wall and planned 2-D diffusion for the side walls, the HF energy will remain in tack and not be a 'dead' sounding room thus making the musicians appear in the room. I tried absorption on the side wall reflections points using the 4 GIK 242's and while it killed the refections it also killed the HF energy so I was always wanting to turn up the volume to compensate - clearly something's wrong. HF absorption and too much of it makes the room sound like headphones - I have a pair of headphones so I don't need a dedicated room to duplicate that sensation thank you. So in summary, if you want to hear all the musical details use headphones, but if you want that live feeling that comes from the sensation of the musicians being in the room then keep it as live as possible by minimizing HF absorption using diffusion. Depending on your mood, you now have a choice . . . Hope this insight helps others with their acoustic room treatment plans. kevin
Musicfile - I agree, Bryan at GIK is very customer focused and generous with his time. I have a big 80Hz peak and he's taken time to suggest numerous locations of bass traps to try out, measure, move, and measure again . . . The treatments are a labour of love but worth it. I guess I'm about 50%-67% of the way finished with acoustic treatments - just have to do the ceiling, front wall and more diffusers on the back part of the side walls.
I would be up for a visit/listen to each others system in the new year. Lets stay in touch. cheers, kevin
