Hi Kevin. Sorry I haven't posted back, but I've had the french drains installed, and the heat pipes replaced/moved so now I'm having the permanent generator insatalled which involves running elecrical and gas lines before putting up walls.
I got Toole's (and other's) book and they all have been very helpful. By the way, I'm very much onboard with diffusion in certain applications since that "live" type sound is exactly what I'm looking for. I'm working with and getting estimates from contractors to see what they're able to do, and I'll certainly report back once the walls are up. What I do know is that I'm incorporating all of the feedback I got from this site (and the books recommended) and it was incredibly helpful in intracting with contractors as it seems most of them are not really familiar with the kinds of things we audiophiles are looking for. Anyway, Happy Holidays to all. |
Six,
It has been about 3 months since you posted your thread. Care to give us an update on where your construction project stands and the acoustical treatment decisions you've made? |
IMHO, HT demands a room with lower reverb time as a lot of ambient info is accounted for in the surround tracts. Lower reverb time allows for improved speech clarity for HT dialog. Many acousticians shoot for an RT60 of 0.3sec in mod sized room.
In two channel music playback especially classical music, slightly higher reverb time improves the body or "sonority" of playback. Many acousticians shoot for RT60 of 0.35 to 0.4s in the mod sized room. Sure enough, acoustically dead room with maximal damping similar to an anechoic chamber would allow most insight into the recording. This is why many master studio/control room has RT60 of 0.25sec. The playback would not sound particular spacious and the speakers would have a tough time disappearing (very high ratio of direct sound vs indirect sound). These are the very qualities which many audiogoners strive for.
Most people in this hobby are not just after how a recording is made. I would think most wanted to create a musical involving experience which strikes a balance betw sonority and adequately low reverb.. Diffusors are great tools to cut down on slap echos without killing reverb. so clarity is maintained without sacrifizing sonority.
The theoretical ideal of an anechoic chamber is not easy or practical in most home situation. The midrange and highs can be easily absorbed but bass in most moderate sized room would be subject to many boundary effect which includes both boost and cancellations. Just look at the speaker measurements from stereophile where some efforts are spent to create pseudoanechoic measurement. Yet they differs significantly from same speakers measured by soundstage done in NRC. There is certainly the phenomena of acceptable bass rise (in reverb) but one need to experiment to see how much bass rise is desirable.
In tuning my room, I have got the RT60 to 0.25 to 0.28 and the detail, microdynamics and image specificity are very good. However, most listeners that come thru dislike the experience and feels the music is not flush out, harmonics are stunted, etc.
A lot of room tuning requires experimentation and learning. Not only learning about room acoustics but also about your own listening preference/priorities. I would choose an acoustician that is flexible to your needs, provide continuous supervision during construction and repeated experimentation after the initial phase is complete. There are many factors that mathematical modeling cannot predict.
After learning how to do the room measurements, you should learn how the measurements translate into what you are hearing. Then you can pick your compromised when faced with two opposing issues. At the end of consultations/contructions/reconstructions and there are areas of dissatifaction. Don't let measurements or consultants convince you that this is the sound you want. Continue to experiment and learn about psychoacoustics.
Regardless of expense or effort, I doubt there is a "perfect room". You may not even like an objectively perfect room. What you need is the right room for your enjoyment.
Good luck |
For my tastes I don't want to listen to either reproduced or live music in an acoustically dead room. Hi Soix, There is NO ARGUMENT with taste and or preference. I prefer to use the term "acoustically neutral" rather than DEAD since what I am referring to is hearing the original sonic information without the distortion of reflections. I should also make the distinction that this DOES NOT apply to LIVE VENUE performances where natural reflections become part of the actual performance, and not distortions. Theaters are different because you've got multiple surround speakers creating reflections and ambiance you'd normally hear naturally in a lightly or untreated room. To each his own as usual. Again there is NO disputing personal preferences, but in two channel reproduction overlaying "your" rooms echos and decay times on top of the original venue's same will not produce accuracy. That said, again it is often not the goal of the user to be accurate. In fact most often is is produce a "prefered" sonic. As far as HT (which is what i thought you were looking for) my main thrust was to know that Acoustic Isolation, (of the room) and Acoustic Treatment for accurate sound, are two distinct and different goals. In my case, I am far more forgiving of Acoustical Accuracy in a HT since virtually ALL of the sound heard in films is manufactured in post production sound studios. Foley, voice dubbing, musical scores, and sound effects are all less critical to me than attempting to recreate a LIVE recoreded musical event in my space, without allowing my space to intrude upon it with its own sound stamp. Good luck with your project. |
Streetdaddy - if you have GIK D1s laying around then sure go ahead and place them at your side wall 1st reflection points to see if it makes it 'less dead' sounding. If you don't have them, then try a sheet of plywood angled so that lateral reflections are sent upwards to the ceiling or sent behind you to preserve the mid/high freq energy.
Summitav - I would agree with you that any indirect reflection is a corruption (e.g. temporal or spectral) of the original direct signal, so as such, may be labeled a distortion. If your mindset and taste is for purity of sound reproduction then you ought to consider listening through headphones. Even in a well damped room such as you enjoy you cannot absorb the low bass frequencies unless it's a huge room where the first modal frequency is below auditory threshold levels. So even an absorbent domestic room will only be absorbent across a limited set of frequencies skewing the reflections you wish to absorb fully. Reflections at glancing angles won't be absorbed so yet again indirect reflections persist.
I like to think in terms of limiting the bad sonic effects of a room while leveraging the positive sonic effects. Get the room working for you not against you, so to speak. Hence the suggestion that not all reflections are bad and those that are should be absorbed or diffused and those that are good should be left alone.
Like I mentioned previously, sonics are as personal as your taste in music. There is no one right way. |
For my tastes I don't want to listen to either reproduced or live music in an acoustically dead room. Theaters are different because you've got multiple surround speakers creating reflections and ambiance you'd normally hear naturally in a lightly or untreated room. To each his own as usual. |
* your wall-to-wall carpet will absorb much high end energy so you will need to pay attention to how you treat your room's surfaces so as not to create a dead sounding room with low reverb time for middle and high frequencies. Try using reflection (i.e. bare wall) and diffusion for middle and upper frequencies and absorption for bass frequencies. Hi Kevin, I liked all your suggestions but might slightly disagree with the above. The best room I ever heard was a room that I "didn't" hear. ANY, and I mean ANY reflected sound is a distortion to the original signal. Go into the best movie theaters built (I have a lot in my area) and they are sonically DEAD. I have a huge MANN here in Westwood and if you arrive early you will sit in sonically dead silence, sans the conversations that go on around you which are now MUCH MORE clear because you don't have echo, reverb and reflection. It is a nasty rumor/myth that acoustically dead rooms don't sound good when the Music or Movie is playing. Unless you need reflective surfaces for Dipole Speakers to function better, it is my opinion that the sound will be MUCH more accurate, clear and certainly less phase/time distorted when reflections are reduced or eliminated. Just my opinion of course. Yes, I have spend thousands of hours listening in near anechoic conditions, which is the question I often get. While a SUPER DEAD room sounds strange when no music is playing, (as it should) when the music begins, the purity is unbeleivable. This is also true of LIGHT. If you have a front projection system, the LESS LIGHT and Reflected Light you allow in the room the more accurate, clear and precise the picture will look. Hope that makes sense and maybe begins to dispel some of the incorrectly held beleifs about "using" reflected sound to pump up a specific frequency range. Distortion is never a good idea, and reflected sound IS distorted sound to the original signal or sound from the speaker. |
One man's overdamped...
Personally, I've been in several highly-damped rooms and don't like them. For me they suck the life out of the listening experience, although I agree you can focus on the individual sounds since you don't have to be bothered with all those pesky ambient cues.
Anyway, after reading the Geddes book it was most helpful to learn that some reflections can be good (taste-dependent of course) and can enhance the listening experience if, like me, you like to hear those things. That's why I'm going with bare walls and was planning on diffusers on the side walls and absorptive stuff behind the equipment -- not sure what yet.
Problem - I really want dimmers and recessed lighting. I'm running dedicated lines and my builder is recommending LED lights, so I'm hoping that will somewhat mitigate the effects of a dimmer if I can find a good one. No? Do LED lights come in 120V, and are those the ones to get? Too many options sometimes.
I'm concerned about getting the junction between the ceiling and walls right since my builder isn't well-versed in these things and it could really screw up the works (I'm also concerned about his workers short-circuiting the hell out of my resilient channels as well).
This is exciting, but it's also more than a little frightening since a lot of these decisions can't be easily (or cheaply) reversed. Ugh. |
I use absorption on the side walls and it's not overdamped. As long as you leave space between the treatments you should be ok. |
Kevinzoe,
I have absorption on the side walls. I also have wall to wall carpeting, and think i may be overdamped. Would you recommend trying a pair of the GIK d1's at the 1st reflection points? |
Soix - I was in your shoes about 5 years ago. Exciting times and certainly enought to learn that will take some time to digest and internalize.
Using my basement 2-channel room as an example, here are some of my learnings:
* use a solid core exterior door to keep sound inside the room
* HVAC: I used a round flexible tube with sound insulation on the inside. You want to install it in such a way that there are several near-90 degree bends in it to prevent sound from traveling back to the furnace and up through the rest of the house. Also, baseboard heaters are dead quiet as another option.
* Lighting: don't use dimmers! They hum and your stereo system will pick it up. Instead use lights that work on 120volts (assuming you're in North America) and that don't use a transformer which can introduce humm.
* use J-molding and an acoustic sealant between the ceiling and walls so that if the walls move they don't transfer energy to the ceiling and vice versa.
* your wall-to-wall carpet will absorb much high end energy so you will need to pay attention to how you treat your room's surfaces so as not to create a dead sounding room with low reverb time for middle and high frequencies. Try using reflection (i.e. bare wall) and diffusion for middle and upper frequencies and absorption for bass frequencies.
* get a Dayton Audio Omnimic or XTZ or similar product to take in room measurements so you can do before and after measurements to gauge how effective your treatments are.
* buy Toole's book.
* not all reflections are created equally. Address reflections from the back and front wall as they are the least beneficial.
* experiment with reflection vs absorption vs diffusion at the side wall's 1st reflection points. Reflection provides the widest apparent sound source and maintains the mid/high freq energy whereas absorption narrows the sound source and attenuates the mid/high freq energy but usually allows for the best retrival of musical details. Diffusion is like the best of both - it widens the apparent sound source to something more akin to a live performance while preserving the mid/high freq energy and allows nearly as much musical detail retrival as absorption. Personal taste prevails.
* If you're considering diffusion within your room and if the sitting distance to the side and rear walls is short, then use diffusion that either is two dimensional (e.g. RPG Skylines) so that only about 50% of the sound is scattered back to you latterally, or a diffuser that doesn't provide temporal effects (e.g. phase) such as geometrical shapes like round surfaces.
Pictures in my 'System' will show what I speak of.
And have fun as it's an itterative trial and error kind of experience. |
Thanks for all your input -- most helpful as usual. I've decided to use Dietrich RC Deluxe resilient channels on the walls and ceilings, double 5/8" drywall w/ Green Glue between the sheets on the walls and double 1/2" drywall & Green Glue on the ceiling, wall-to-wall carpeting, and LED lights (contractor says they're the quietest w/ dimmer) if budget permits. R30 insulation or maybe special insulation, again if budget permits. Not sure about absorbers/diffusors yet, but I'll fight that battle another day after the room's done.
Thanks again, and I'll follow up with results after it's done in case anybody's interested. |
Summit, well said. Sound proofing only keeps the sound inside a room, nothing about making the sound inside the room any good!
The basics are to avoid parallel walls, hard (reflective) surfaces where the speakers project sound (usually the side walls). Using commercial grade absorption from any of the major companies on the sides and behind the speakers can really help. Many companies offer room kits, which is perhaps the ideal starting point for most of us, really simple and a huge improvement.
Being from the pro side, I cannot help but chuckle a bit when I see folks with these extremely expensive systems, hi end power cables, CD vibration isolation etc, speakers near side walls, all in an untreated room. That's like $10,000 in tires on a 1971 ford pinto! |
There is a difference between Acoustic Treatment, and Acoustic Isolation/Sound Proofing.
There are also differnces in Acoustic Treatments to 1) Listening/Reproduction Rooms for Audio 2) HT rooms 3)Live performance Rooms/Venues.
And lastly, there are different treatments for 1) Sonic Accuracy and 2) Sonic Preferences.
The solutions you use need to take these paths into consideration. Quite often the goals get homogenized and you don't get the desired results. |
I did a rives level 1. Didn't quite like it. May not be design fault. Could be construction fault. Anyway I read up gearslutz dot com. Plenty of info about room acoustic. Re do my room with prime root diffuser with plenty of bass trap at rear wall using ecophon ( much better than normal rock wool but expensive). Like my room acoustic better now |
May I suggest the following.
Drywall. Use different thickness on all surfaces. Eg front wall 2 layers of 5/8, left wall 1/2 and 5/8, right wall two of 1/2 and back wall 5/8.
This way none of the wall will "vibrate or resonate" at the same frequency.
Apply first layer of drywall to studs with green glue , great product. For the next layer of drywall use a large V notch trowel applying drywall mud over the whole surface of the first layer of drywall. This will make the two sheets bond over the whole surface and will not have any air voids. Be generous with the drywall mud.
If you would like further info you can send me a message and I can go further into this subject.
Good luck and take care, |
For information on soundproofing, take a look at the Soundproofing Company website. They have quite a few articles on soundproofing techniques and can give you good advice regarding resilient channel and green glue. Resilient channel certainly works, as long as the drywallers know how to deal with it. If you want to go with just one layer, you might look into the mass loaded drywalls, although they are expensive. Ted at Soundproofing Company has real world experience with rooms for audio. Give him a try. |
I found the Geddes book to be very helpful. Fairly concise and mentions specific products he's used that work well, which was exactly what I needed.
Anyway, I've decided to do the resilient channels and was relieved my contractor has actually worked with them (I think mainly in commercial applications). However he's advocating using a single layer of drywall into the channels, and then a soundboard between the channels and the studs. My bias is to use two layers of drywall damped by liquid nails or green glue into the channels and the channels attached directly to the studs. Any thoughts on this? Thanks yet again for any thoughts. |
So, for several reasons (cost, I might not be in this house for a long time, etc.) I've decided to do this on my own (with a contractor) without using an audio room design expert. I got all the books and have begun going through them. There's a lot there and I've got a lot more reading to do, but even at this early stage I had some major questions I was hoping some of you may have some thoughts on.
- I have to decide what materials to use in constructing the walls and ceiling. It would be particularly helpful if you could recommend specific products that have worked well (i.e. wall type/thickness/installation techniques, ceiling tiles type/installation, acoustic caulk, flooring tiles, carpeting, etc.) and where's good to purchase them.
- I'd also like to incorporate some sound isolation to the extent that I can, although I probably don't have all that much in the budget to do it. The ASC Isodamp system seems like a good one, but wondering if anyone has experience with this or if there is a lower cost and/or easier way to achieve a lot of those benefits? Also seems like it may eat up some space in my room, which is not a deal breaker but not optimal. Specifically I'm wondering if there's some kind of acoustic damping material I can just apply between the studs and walls(and between two wall boards if doubling up is recommended)/ceiling tiles to achieve at least some kind of isolation if something like the ASC stuff is out of my range.
- After I have the walls and ceiling up I'll need to incorporate some room treatments. Anyone have any opinions on ASC products versus RPG (or any others for that matter)? They seem to use different technologies that affect sound differently. Also is one significantly more expensive than the other to accomplish similar results?
- I'm getting mixed signals on the floor. Some prefer some form of wood flooring with area rugs while others prefer tiling/cement with wall-to-wall carpeting. I'd prefer the latter for practical reasons, but wondering what your experience is.
My first priority is sound quality in the room, but if I can achieve a good amount of soundproofing without adding several thousands to the cost of the project that would be a big bonus. Thanks again for all your thoughts and help. |
Thanks so much guys, and by the way I should probably mention this is first and foremost a 2-channel audio system (our home theater is upstairs) although I may run some surround channels at some point in case I ever start experimenting with multi-channel music. I'm absorbing all of this and will get the books and contact at least a couple of the people you recommended. Duke's first sentence pretty much summed it up nicely, and what I know about construction in general (much less construction of a good listening room) could fit on the head of a nail. So all this info. is fantastically helpful, and by all means keep it coming. |
I did a similar project in my last home. I focused on 3 main points:
First, fir out the walls (if necessary) to acheive a good length x width ratio. IIRC, 1.4 to 1 was the recommendation in the book (similar to the Geddes book Duke cites) that I used.
Second, Try to break up parallel wall surfaces with some "ornamentation". Light fixtures in columns, shelving, etc. I also used a center ceiling drop and stadium seating so that ceiling and floor weren't parallel.
Third, I mixed absorbtive and reflective material. Wood panel wainscotting from the floor up to +/- 3' and a canvas-like fabric backed by acoutic foam the the 3' "beltline" to the ceiling.
The result was drop dead gorgeous and great sounding, but....
This was a stupidly expensive project. I suspect that you can probably get to a similar place on a lower budget while still employing these ideas.
Good Luck,
Marty |
Since you will be using basement space, the key will be to isolate the sound of all the mechanical equipment and its duct work. Hard to do. Until you get that right I would suggest not spending any money building the room itself. Also, read Floyd Toole's book 'sound reproduction'. |
The most critical time of any major project is at the beginning, when the biggest decisions are made, and paradoxically when you know the least. Apparently you are aware of this, and seeking to learn as much as possible at this early stage, which shows good judgment.
"Premium Home Theater: Design and Construction", by Earl Geddes, was written with Soix in mind. Totally worth the price, even for two-channel guys.
If you decide to seek professional assistance, I highly recommend Jeff Hedback, of Hedback Designed Acoustics. He can help make all the right things happen in YOUR specific room by a combination of remote measuring and professional analysis.
Duke
dealer/manufacturer |
Look at my system to see a very affordable way to make a room that sounds incredable.
Do a little reading for some tips. |
Check out the web sites for the following companies:
Rives Audio
Cardas
Acoustic Sciences
All of these will provide information, ideas and products. Rives and Acoustic Sciences also offer tiered consultation that is very effective and both acoustically and financially. Good luck. |
