Music from a farther room

Music from the NEXT room - update 1



This update is a continuation of my thoughts and experiments in creating a good listening environment within the confines of a small listening room measuring approximately 17ft x 11ft. Starting with the shell of a room that started life as a ground floor garage this update together with others that will follow will chart key conflicts, decisions and progress towards what I hope will be a new and rewarding approach to small room acoustics.


The first obvious step of preparation for the new audio room was to remove all existing wall linings so that improved insulation and better quality wall linings can be installed and provisions can be made for dedicated AC power circuits, specialized earthing and data networking.


The obvious nature of this first step however concealed a huge dilemma I had to work through before the carpenters started work. Put succinctly the nagging question was – what overall building element performance (STC/Rw etc.) was required to meet a desirable level of acoustic comfort?


Determining the acoustic comfort design level requires balancing several factors such as budget, owner and occupant expectations, building code and district plans, organisational standards, and the intended function of a room or space. It can impact on junction details, building service placement and containment, room layout, construction types, and quality assurance programmes.


I have long believed in the benefit of quiet spaces in which to enjoy music. Quietness demands noise control and by extension isolation from unwanted noise. The benefit for audiophiles of a quiet environment is multi-fold. First, unwanted noise such as the sound of cars passing on a nearby road or the footfall of children in nearby rooms – which is distracting – can be eliminated or a least reduced. Second, a quiet room, one with a very low noise floor, will improve the possible dynamic range of your audio system. Simply put therefore, the quieter the room the more things you will hear from a recording and the less distracted one will be by noise (unwanted sound).


The design of my previous audio room achieved a measured noise floor of 30dB, not bad when you consider there was a fairly busy road outside the window and that a typical home does well to achieve 50dB SPL.


Aiming for some targeted level of acoustic comfort is an important prerequisite to establish because it aids in estimating how much noise attenuation is needed. For example if the sound of cars passing outside the window of your desired listening space measures at 75dB and you desire a target noise floor of 30dB, then design for your room must ensure an STC of 45.








Once a desired level of acoustical performance is locked down attention then turns to design elements (walls, ceilings, doors, windows etc.) required to achieve the goal.


Looking first at drywalls [I will address other elements in a subsequent update] several builders books state that thicker drywall reduces sound transmission but engineering manuals recommend using multiple layers of drywall, sometimes of different thicknesses and glued together, or special type of drywall designed to reduce noise. Also important are the construction details of the framing with studs, wider stud spacing, double studding, insulation, and other details reducing sound transmission. Sound transmission class (STC) ratings can be reduced from 33 for an ordinary stud-wall to as high a rating as 59 with double 1/2" sheetrock on both sides of a wood stud wall with resilient channels on one side and fiberglass bat insulation between the studs.




THE DILEMMA


Herein lay the first dilemma. Whilst it is relatively easy to increase the thickness of drywalls either via increased thickness of materials or double / staggered studding or introduce a brick internal wall for increased rigidity we run headfirst into a well-documented problem. One of the great ironies of acoustics is that thick rigid walls that improve isolation between rooms will also cause more acoustic problems within the rooms. With standard walls made of one layer of sheet rock, the lowest frequencies pass through to some extent, and are also partly absorbed when the wall vibrates in sympathy. Walls made of cement or multiple layers of sheet rock reflect more and to lower frequencies, thereby increasing the damage caused by acoustic interference.


Low frequency energy passes right through the lightweight walls to the outside; and by passing through the walls instead of being reflected, the low end response is more uniform than in many rooms. For this reason whilst I am desiring an STC performance of 45 I am wanting to achieve this with a relatively lightweight structure so for this build I will be using single stud with two layers of relatively thin (10mm) GIB board affixed internally as shown in figure 2 below.








In my next update I will discuss some of the other design elements and decisions around them; notably the windows and ceiling.

Music from the NEXT room - Update 2



This update is a continuation of my thoughts and experiments in creating a good listening environment within the confines of a small listening room measuring approximately 17ft x 11ft. Starting with the shell of a room that started life as a ground floor garage this update together with others that will follow will chart key conflicts, decisions and progress towards what I hope will be a new and rewarding approach to small room acoustics.


This particular update addresses the window and how its design addresses different types of noise; airborne and impact.



NOISE


Noise is any sound that is unwanted, usually because it distracts or disturbs us. Noise can come from a variety of different sources but there are only really two forms: Airborne - These are sounds which travel in waves through the air and enter our ears. Airborne noise can travel from outside a building to the inside. Typical examples are:


• Music
• Children playing
• Traffic noise


Impact - These are sounds that are transmitted via vibration through a physical structure such as a conservatory roof. Typical examples are:


• Rain
• Hail



ACOUSTIC WINDOW


The weakest links in reducing the level of sound transmission between rooms and to the exterior tend to be windows, doors and ceilings. The challenge for these building elements is to bring them up to an acoustical performance level that is not too similar to the outside envelope of the home. There is little benefit in having STC 59 rated exterior walls if those walls are punctuated with large windows with an STC 29 rating. If a room design is targeting a sound transmission class of 40, then all elements of the design; windows, doors, ceilings etc. must come up to that standard.


Most acoustic control rooms in broadcast / recording studios achieve high STC ratings by having fixed pane (non-opening) windows with large air-gaps, often 4” between the glass panes. Unfortunately non opening windows with large air gaps are not an option for domestic houses so some compromise is necessary.


People assume that because insulated glass does a better job of reducing heat transfer, it will also do a better job of reducing the transfer of noise. This is almost always not the case. In fact the small air gap that is typically found in insulated glass and is so useful for its thermal properties, is usually a disadvantage acoustically. The air in the gap couple (not isolates) the two sheets of glass, thereby improving the ability of a thermo-pane window to transfer sound energy.


For acoustic properties the preference swings to laminated glass. Using laminated glass (two or more layers of glass bonded together by a visco-elastic damping layer between them) the STC of a window assembly can be significantly improved. The damping layer, although very thin and not visible, improves the overall glass performance (increases STC) by eliminating or greatly reducing the losses that inherently occur at coincidence frequencies in single panes of glass. It should be noted that in colder regions the improved STC provided by laminated glass will be reduced as the damping layer is substantially cooled. The air space between glass sheets in commercial windows can be as little as 0.25” and is generally no more than 1”. The acoustical performance of such assemblies is inherently limited by such small air gaps. Generally, acoustically rated windows have spacing of 2” – 4” between panes. The airspace between the panes should not be less than four inches if an STC above 45 is desired.








Acoustical windows can be purchased factory-assembled or they can be constructed locally (in a shop or on-site). Any window purchased from a factory should have been tested acoustically and should come with a guarantee of performance.


Working closely with my builder we eventually settled on a solution from Viridian Glass (formerly Pilkington Glass). That solution was Viridian VLam Hush™ which is a laminate that uses a specially developed interlayer to dampen noise, providing enhanced sound insulation performance. This means that thinner and lighter glass can be used for equivalent acoustic performance. VLam Hush reduces the coincidence dip of standard monolithic and laminated glass.











The window comprises of double glazed 7mm Stadip Silence Laminate on 7mm Stadip Silence Laminate with approx. ½ inch between the panes. Each pane contains a special acoustic interlayer (approx. 1mm) which not only bonds the glass but also acts as a dampening core between the glass panes, preventing sound frequencies vibrating from one pane of glass to the other. This interlayer absorbs and weakens sound, helping to act as a barrier to both airborne and impact noise. Normal windows have a ‘resonant frequency’, at which they vibrate more significantly reducing their acoustic insulating performance. Stadip Silence double glazed units perform at least 20% better than conventional units comprising annealed or normal laminated glass. At the critical resonant frequency they can perform up to 10dB better. If a window incorporates an opening of any kind it is important that well performing seals are also fitted. Sound will travel through any small gap and will have a detrimental effect on the overall acoustic performance of the window.

An air gap of only 1% of the total window can reduce the sound insulation by up to 10dB, meaning that the noise passing through sounds twice as loud as it would if well sealed.


The STC rating for the glass in the above mentioned configuration is approx. 40. Though it is important to note that the window by design limitation will be more suitable for blocking higher pitch frequencies. Lower or deep pitch frequencies whilst muffled will still possibly audible.


In the next update I will provide insight into the isolated ceiling design.

Nice view on your backyard.

Hi Ralph,

Curious, have you looked into quiet curtains or the like to reduce unwanted noise? Just wondering if you did and know of their effectiveness vs. the glass solution you are using.

Thx

Ralph, I always look forward to your posts. I find them extremely informative. Your observations and actions are well thought out. You'll have to put up a bibliography at the end of your thread. I wouldn't know where to go to find all of the info that you have assimilated.

Le Roy

NorthStar said:

Nice view on your backyard.

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LoL. Thanks for overlooking the shoddy lawn trimming/edging Bob….

socfan12 said:

Hi Ralph,


Curious, have you looked into quiet curtains or the like to reduce unwanted noise? Just wondering if you did and know of their effectiveness vs. the glass solution you are using.


Thx

Click to expand...

Hi Allen, indeed I have looked into quiet curtains. For my previous room I imported at considerable cost Quiet curtains from a supplier in San Diego, CA. The curtains, with a very heavy proprietary vinyl liner and thick suede fronting fabric claimed a lab tested STC 20 rating. They required special heavy duty tracks and carriers to manage the weight. I not only fitted the curtains to my audio room but also installed them into my master bedroom – as both faced an urban street, so I had reasonable opportunity to observe their effectiveness.








How effective were they? Well, I did not objectively measure their performance but observationally I struggled with the STC 20 rating. The rating is a result of measuring against a specific contour, typically from 125 Hz to 4000 Hz, with the focus really on the effectiveness of attenuating speech. Needless to say the product is more effective at frequencies above 1 KHz – but even here when I had my son stand and speak on one side of the curtain I am pretty certain the sound I heard on the other side of the curtain was reduced no more than 25%, nothing close to expectation. That of course was a hardly scientific exercise and flanking may have played a role. Equally for low frequencies, typical of traffic noise, a quiet curtain is not effective.


In sum – and sorry about being long winded – a quiet curtain can’t be considered as an alternative to an acoustic glass window solution. By merit of its mass and interlayers a window will be more effective at noise reduction and importantly over a broader band of noise. At best a curtain should be considered as supplementary. A quiet curtain can however be effective in blocking distracting bright sunlight and reducing room reverberation and echo - which can be a problem with uncovered glass surfaces.

Odyssey said:

Ralph, I always look forward to your posts. I find them extremely informative. Your observations and actions are well thought out. You'll have to put up a bibliography at the end of your thread. I wouldn't know where to go to find all of the info that you have assimilated.


Le Roy

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Thanks for the kind words Le Roy. May be one day I will better organise my observations.

Music from the NEXT room - update 3



This update is a continuation of my thoughts and experiments in creating a good listening environment within the confines of a small listening room measuring approximately 17ft x 11ft. Starting with the shell of a room that started life as a ground floor garage this update together with others that will follow will chart key conflicts, decisions and progress towards what I hope will be a new and rewarding approach to small room acoustics.


This particular update will focus on the ceiling, one of the largest and most important elements of any audio room.

Over years of experiments and observations both in my own audio room and that of others I’ve arrived at several conclusions that will inform my ceiling design. I am not an authority on the topic and others may disagree but I nonetheless state for clarity my observations below:




1. Audio rooms with chapel ceilings are a mistake. As an old audiophile tale goes, the only place where a chapel ceiling is appropriate is a chapel.
2. Ceiling light fittings should be avoided. Ditto for florescent lighting and dimmers too.
3. Avoid ceilings that act like trampolines. This is especially relevant in basement rooms where joists typically bear a floor load above.



As earlier recited noise can come from a variety of different sources but there are only really two forms: Airborne – being sounds which travel in waves through the air and enter our ears and Impact - These are sounds that are transmitted via vibration through a physical structure such as a footsteps on a floor above.

Since my audio room will have human traffic on a directly above floor the ceiling design must attenuate both airborne and impact noise.


In order to attenuate airborne noise insulation is typically used. I found that 250mm (around 10 inches) was needed in the ceiling which in conjunction with 13mm specialised GIB Noiseline board met my targeted level of acoustic comfort.

In order to attenuate impact noise a resilient channel is necessary to decouple the ceiling board from the flooring joists.







The design avoids the use of ceiling lights for three reasons. First, any holes punched in the ceiling will weaken the ceilings acoustic performance. Second, given the ceiling is already quite low, lights will further reduce the perceived height. For this room soft wall mounted lights will be employed instead. Third, the close proximity of insulation to recessed light fittings can produce a fire hazard.


An abundant amount of acoustic sealant is used at wall intersections and great care is needed to ensure that screws used to secure the ceiling board to the metal channel don’t tap into the joists.






In the next update I will provide insight into the electrical aspects of the room.

Ralph, this update is on par with your others, most excellent.

I have a number of questions I would like to pose to you; however, I shall confine myself to one at this point: Do you believe that it is still a mistake to use dimmed lighting that is on a separate circuit from the presumed dedicated circuit for you Music Room?

Often times dimmed lighting is used to set a mood or to enable one to better concentrate during periods or critical listening. If there is no interference with the havoc a dimmer introduces into the electrical current, does your admonition stem from something else?

Just one more question for now: when do you expect for your room to be complete?

Le Roy

Hi Le Roy,

In reply to your question I avoid dimmers even where (as they will be in my room) they reside in separate power circuits.

The issue is one of potential harm caused by hum. See Kill Studio Hum and Buzz at the Source
for interesting discussion on the topic, including one possible solution using large variable power transformers, something I did not consider as practical due to size.

I agree with you that mood lighting is beneficial so my room design calls for mood lighting (sans dimmers) and separate task lighting and I will detail this together with other electrics in my next update.

ETA for room completion is 4 weeks. There was long lead times on my acoustic doors and acoustic drapes.


Regards
Ralph

Ralph, interesting and informative read as usual. Well done. :scholar:

Ralph, when you finish your flooring treatments are you going with carpet and padding or some other floor covering? Are you going to lay some kind of wood underlaymnet (3/8" or 1/2" plywood) as a buffer between the concrete and the floor treatment? What are your views on concrete or cement structures and how they will affect the sound within the room? Thank you for all of the pics.

Le Roy

Odyssey said:

Ralph, when you finish your flooring treatments are you going with carpet and padding or some other floor covering? Are you going to lay some kind of wood underlaymnet (3/8" or 1/2" plywood) as a buffer between the concrete and the floor treatment? What are your views on concrete or cement structures and how they will affect the sound within the room? Thank you for all of the pics.

Le Roy

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Hi Le Roy,


Thanks for the interest.


From the outset I should state that I am endeavouring to build a room around my speakers – rather than the traditional approach of buying a pair of speakers and praying to God that they work ok in a pre-existing room. It is important to understand this foundational position because it will be basis of many decisions I make including the flooring treatments.


Turning directly to your question, the room has a concrete slab base and flooring treatment will consist of 12mm foam underlay with sisal wool carpet laid on top.


Why I have chosen this solution really comes down to my speakers. In my previous listening room I had timber strip flooring over a concrete floor. This did not in my opinion work well because the flooring was not perfectly level and as a result my speakers did not sit properly. Furthermore, the relative lack of a buffer between the concrete and the timber led to a leaner overall sonic presentation. The problem was solved by introducing a thick carpet rug. You may read elsewhere of others siting their Raidho speakers on granite or ceramic slabs or tiles or even adding spikes to their speakers. While such choices obviously reflect personal preference they defeat – in my opinion – the effort that has gone into Raidho’s clever footers which serve a critical purpose. Spikes, granite et. al. act like tuning devices and they will nearly always “lean out” the sound. In an effort to maximise the potential of the speakers I plan to ensure that Raidho’s footers have good grounding to the carpet but don’t compress it to the extent that they will connect to the concrete. Wool carpet was an obvious choice as for reasons I can’t explain it sounds better than synthetic carpet – an opinion that does find some support of other audiophile community members. Rather less obvious was underlay selection where the choice is between rubber waffle, slab rubber or foam chip. I really don’t know which is best but I do recommend avoiding cheap underlays of any type. Clay fillers may have been added to basic rubber waffle underlay to keep down the manufacturing costs. In time the waffle structure may collapse as the fillers break down. Cheap low-density foam underlays with a density of less than 95kg will quickly lose their resilience and maintain indentations. Foam chip underlay which I’ve selected is graded by density (kg/m³) – and the higher the better from the point of view of feel, durability, thermal properties and acoustic buffer. I will be using 12mm thick foam underlay with a 120 kg/m³ density.


Turning to your second question re concrete / cement structures I don’t yet have an opinion. My earlier audio room was a concrete bunker with a solid reinforced concrete base floor and cement plaster over brick walls. My hypothesis as of now is that room may have been TOO rigid and so my current rooms design will be experimentally more lightweight in a purposed effort to relatively release rather than store or reflect back energy into the room. Only observation over time will test the validity of the hypothesis.

Music from the NEXT room - update 4



This update is a continuation of my thoughts and experiments in creating a good listening environment within the confines of a small listening room measuring approximately 17ft x 11ft. Starting with the shell of a room that started life as a ground floor garage this update together with others that will follow will chart key conflicts, decisions and progress towards what I hope will be a new and rewarding approach to small room acoustics.


This particular update will focus on the electrical design for the room with a specific focus on decisions taken around lighting. Subsequent updates will discuss power circuits and earthing.



LIGHTING


The right lighting can create a mood, light up a task or accent a decorative feature and when it comes to lighting in an audio room generally all three will be planned for.


Task lighting is essential and located in proximity to your audio rack this is required to provide adequate light for you to make changes to audio connections etc. even if they are on the bottom shelf. You want your speaker cables in the right phase and you want all cables dressed as tidily as possible and hence the amount of light needed here should be enough to accomplish these sorts of tasks. Task lighting can also be useful close to where your music is stored so you can more easily find your record or CD of choice.


While bright lights might be great for entertaining and activities requiring a certain task to be performed when it comes to actual listening to music most audiophiles agree that mood lighting is the way to go.


Light is an element of design which should be used not only for visual comfort, but also to achieve predetermined emotional responses from the lighted environment. Through use of lighting patterns of varying levels of illumination, and of colour in the light source and in the illuminated object, it is possible to produce certain moods such as: solemnity, restfulness, gaiety, activity, warmth, and coolness. The lamps themselves can be used to dramatize elements of interior design—line, form, colour, pattern, and texture.


While higher levels of lighting generally produce cheerful effects and stimulate people to alertness and activity, lower levels of lighting tend to create an atmosphere of relaxation, intimacy, restfulness and focus on the reproduced music rather than the distraction of hard illumination.


While it is tempting to use light dimmers to alter the level of illumination in a room – don’t! With few exceptions (which tend to bulky and / or costly) lighting dimmers can produce noise in the form of hum or buzz. Solid-state light dimmers in particular can create havoc with audio gear. These devices work by changing the amount of time the full power line voltage is applied to the light being controlled, as opposed to actually raising and lowering the voltage. Although AC power is supplied by the power company as a pure sine wave (having no harmonics), the dimmer's sudden switching of the voltage on and off actually generates harmonics which extend to very high frequencies and these high frequency harmonics can get into audio gear both by radiation through the air and also by traveling through the power wiring directly into the audio circuitry.


A superior solution is to place lighting on a separate power circuit (ideally just for the room) and select the appropriate light fitting / bulb size / lumens / colour to achieve your desired atmosphere. I prefer to have task and mood lighting on separate switches to purpose for different activities. Further, my experience has directed the avoidance of installing florescent lighting in the music listening area. Use only incandescent or halogen lighting. I've not done a scientific exploration as to whether it is the aesthetic effect or if it might be electronic hash on the power circuits or both, but music always seems to sound better with subdued incandescent lights.









Personal preference will naturally play a key role in lighting choices. Speaking personally I prefer the following;


1. Wall mount rather than ceiling mount lights. Not only are bulbs easier to change in order to tailor appropriate colour and lumens, they can also produce interesting lighting patterns.


2. An up-down (directional) lighting pattern. This is not only interesting but also more intimate and avoids an undesirable situation of light shining into one’s eyes.


3. A curved form for the light fixing as these will scatter rather than simply reflect certain audio waves.


4. Warm lighting. It must simply be psychological but I find cool lighting = cool unengaging music….


In the next update I will discuss other aspects of the electrical design; power circuits and earthing.

Ralph - terrific job! No stone is left unturned. Very thorough. I'm curious, how long are your speaker cables? Also, I may have missed it, but did you install a solid core door?


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Mike said:

Ralph - terrific job! No stone is left unturned. Very thorough. I'm curious, how long are your speaker cables? Also, I may have missed it, but did you install a solid core door?

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Hi Mike,

Thanks!

In reply to your questions;

I have two sets of loudspeaker cables. One set is 7m the other 2.5m, the choice depending on the location of the equipment rack; either sidewall or between and behind the loudspeaker plane.

I am planning a separate update on doors. The main entry to the audio room will have a special acoustic door and frame and I think a short note on that is warranted as a future update.

Hello Ralph,

I'm using LED lighting without dimmers: I just turn on or off separate LED strips closely spaced together to achieve the required luminosity. Also, using RGB LEDs allows me to choose a color fit to my mood.

P.S. No need for expensive professional stripes, Christmas tree ornaments will do the job (I placed them inside semi-transparent cable masks that can be found in any IT store).

iosiP said:

Hello Ralph,

I'm using LED lighting without dimmers: I just turn on or off separate LED strips closely spaced together to achieve the required luminosity. Also, using RGB LEDs allows me to choose a color fit to my mood.

P.S. No need for expensive professional stripes, Christmas tree ornaments will do the job (I placed them inside semi-transparent cable masks that can be found in any IT store).

Click to expand...

Hi Costin, Now that is interesting. What color do you find yourself listening in mostly?

kiwi_1282001 said:

Hi Costin, Now that is interesting. What color do you find yourself listening in mostly?

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Mostly amber, it's warm enough to put me in the mood but not as strange as, say, red. I too avoid cool colors: green or blue just make everything look freakish.
Sometimes I just use blue above the gear (makes the blue displays look white while keeping almost everything else in the dark).

I must confess I also have a "light organ" (kind of an '80 style toy) that I modified to work with the LED stripes. I keep it on a separate circuit and sometimes use it while listening to Guns'n'Roses, Yello or Kruder & Dorfmeister. Better keep off the 18 years old Laphroaigh while doing this

Hi Ralph,

Great update. I'm not happy with the lighting in my room and as you say, it really sets the mood right. Once my gear settle choices settles down and acoustic treatments are up, I will tackle that next.

Interested in what you do for your door. I have solid core doors, but with a healthy 1/2 inch or so gap on the bottom. Was thinking of getting some door treatments for the bottom to prevent so much sound from leaking...

iosiP said:

[...] I must confess I also have a "light organ" (kind of an '80 style toy) that I modified to work with the LED stripes. I keep it on a separate circuit and sometimes use it while listening to Guns'n'Roses, Yello or Kruder & Dorfmeister. Better keep off the 18 years old Laphroaigh while doing this

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I disagree. A good single malt, a comfortable chair, mood lighting and the sweeping orchestral backing of "November Rain" -- is an epiphany of the divine. It is for such moments we strive tirelessly....