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My New Listening Room

Discussion in 'audio' started by Tenson, Dec 6, 2016.

  1. Tenson

    Tenson Trade: AudioSmile

    Hi ladies and gentlmen and none of the above,

    My wife and I recent purchased our first house. Goodbye renting!

    I am thus setting up my dedicated listening room and wanted to share what I've been doing.

    Firstly I had a choice between the main room at the front of the house or in the middle (back of house is kitchen and bathroom extension). I was originally going to use the front room as it has more light and a nice working gas fireplace. However I decided upon the middle room for two reasons - 1) It has less noise from the road outside 2) It has a 1.3 meter space under the floor.

    Measurments are 4.2m long, 3.3m wide and 2.6m high (not including under-floor space). Nicely in the 'Bolt Area' unless I unclude the under floor space which brings length and height to similar size.

    I'm planning to lay laminate floor qhich will keep the room nice and live in the top end, but the danger is unconrolled mid and modal range from too little absorpion. So I have chosen a wood fibre underlay that can absorb sound, rather than foam type.

    I've also just spent yesterday getting under the floor and have installed 5 significant bass traps in the space below. This is the primary reason I chose the room. My hope is that bass and low-mid frequencies will pass quite easily through the laminate and floorboards to be nicely damped by the treatments below. At the same time mid and highs will be reflected and provide a well balanced acoustic.

    The two biggest traps are in the alcoves either side of the chimney breast below where I plan to site the speakers. There are two smaller ones below each rear corner of the room and one more large onne wrapped around a support under the middle of the floor.

    Still to come, I plan to install some hanging treatments for the reflection points, behind the sofa and a nice rug.

    Original floring removed!

    Initial exploration underground

    Fending off large spider-webs and head-crabs.

    Under the chimney breast.

    One roll of this stuff is huge when expanded!

    Bass trap one and two! Measures 120cm x 60cm x 80cm.

    Installed, with an acoustic grade box to help support.

    Wrapped around the center support. Damn it was dusty down there! Sorry for the foggy photo quality.
  2. Tenson

    Tenson Trade: AudioSmile

    Wow seriously... half my photos are upside down!

  3. gagahoo

    gagahoo pfm Member

    How deep are the foundations , you might be abill to get a nice celler
  4. Tenson

    Tenson Trade: AudioSmile

    Celler is under the front room. Home-made beer and wine to come!

    I think the house must be dug in to a bit of a slope as the under floor spaces get smaller as you move to rooms at the back of the house.
  5. merlin

    merlin Avatar changed - Town names deemed offensive.

    Congratulations on joining the madness. Dinner party conversations will seem less irrelevant in future :)

    My tip would be to work with the room once you are in there. Designing from scratch is IME fraught with danger even when blessed with advanced modern modelling software.

    Particularly when it comes to narrow band absorbtion it's often Russian Roulette so get everything you want in there, then (once you are comfortable and familiar with it) perform a full set of measurements and work on eliminating anything overpowering - that would be my honest advice. Get comfortable first.

    I'm guessing if you are going to put numerous speakers through the room you are going to want something as neutral as possible. In a room that size though such a goal might prove elusive.

    Good luck.
  6. Mike Reed

    Mike Reed pfm Member

    Firstly, congrat's on your first house, which definitely looks to be Victorian/Edwardian. For some odd reason (to me) you seem to be hung up about preventative measures which may be unnecessary, but not on the important bits (i.m.o.)

    With a blank canvas like this and lovely cavities underfloor, why not install dedicated radial circuits? Speaker cables too, once you know where things are going. Also, you don't mention your kit (and esp. speakers), nor show a floor plan, as I can see that door will prevent the chimney recesses being used; mind you, unless you have certain speakers, few will perform well in those anyway.

    Carpet is nearly always better than solid floor for hifi, unless it's a dull sounding system. The size and shape of the room is a wee bit limiting, esp. with speakers, but careful thought needs to be put into siting, I feel.
  7. Cav

    Cav pfm Member

    You have moved into your first house and you are putting bass traps into "significant" under floor areas? How do you know what is significant?

    Are you completely mad?
  8. Tenson

    Tenson Trade: AudioSmile

    Good advice Merlin. I am only doing the under floor treatents now as it won't be very practicle to get under there once the floor is laid.

    I'll do some measurments once stuff is in there. Though I am quite sure I'll need something to treat the wall behind my listening position and the side reflections.

    The door you see to the side of the alcove is to access the cellar so will not be in constant use. Once speakers are in place there should be room fo a person to slip through the door and if a large item needs to be moved then the speaker can slide over. I'll probably mark the position with a bit of tape.

    I don't feel the size is limiting. Larger rooms don't always sound better especilly when comapred with a dedicated room with no limits on physical treatments.
  9. Rug Doc

    Rug Doc pfm Member

    What a fun project! From my personal experience, i'd buck teh trend and have the speakers firing across that room.. I have a similar sized space and yes the system sounded very alive and powerful from the short side, but far far more cohesive and a with a far wider and higher soundstage firing across the room. I understand you're excited, as would I be, but you need to get your equipment in there (and soft duvets) and set things up to decide what sounds best rather than deciding now and then forcing it to work..
  10. Tenson

    Tenson Trade: AudioSmile

    I thought about that, but in my last two abodes I've had the system on the long wall and want a change.

    Every room tends to need damping for the main standing modes, so I don't think this is something I'm going to regret once I get kit in there. As you can see I have not used tightly tuned absorbers.
  11. peter bj

    peter bj pfm Member

    Very interesting project , do keep us informed of progress
  12. Mike Reed

    Mike Reed pfm Member

    And your kit?
  13. Hipper

    Hipper pfm Member

  14. martin clark

    martin clark pinko bodger

    While you're down there, Simon, make sure you cannot easily poke a penknife into any of the joist ends, nor occlude any external vent bricks with the treatment.

    Congrats meanwhile!
  15. Tenson

    Tenson Trade: AudioSmile

    Thanks. It's good to read others saying the bass will easily go though the flooring. I've got so much space below the floor I don't need to build a diaphramatic absorber. The sheer size of the bass traps will do the job and proove more linear across frequency.

    Kit is various. Floorstanding, standmount, closed, ported, passive, active speakers. Mostly driven by digital streaming from Spotify and a ripped CD library in AAC. It will be a treat though to finally setup the turntable I've had in storage. Perhaps not such a treat to hear how worn all the old LPs from my youth are! I'll probably use thm as decoratio nmore tha nnaything ;)
  16. Tenson

    Tenson Trade: AudioSmile

    Cheers Martin! (I poked my head in to a few joists). I've pactched up the floor now so can't check the joists. I didn't block air bricks. There is one air brick that would have opened to the back garden but there is now a consevatory exenson there.

    I'm sure the survayer I paid will have checked everthing carfully... haha no just kidding ;)
  17. jimification

    jimification pfm Member

    [YOUTUBE][/YOUTUBE]Congrats on your new place! I have a very similar room / underfloor void to you in a Victorian terrace with a suspended floor. Coincidentally, I even made bass traps under the floor from exactly the same stuff as you. The bass traps helped a bit but suspended floors really are a bugger - it's like playing music on the skin of an enormous drum. It might be worth trying to stiffen up the floor with a couple of extra supports while you're under there. Maybe consider extra reinforcement under the speakers too. Also worth bunging in a radial or two while you're there as Mike said.

    The other thing is the parallel walls but if you can go nuts with room treatment you should be ok (I can't as it's our sitting room - if you clap your hands those walls are very reflective and give great flutter echo) Our speakers fire down the room (it's a knock-through).

    What's at the other end from the fireplace? Is it a bay?

    One thing that works quite well in ours is the speakers positioned just at the inner corners of a half-hexagonal bay. That means there's no surface behind them that reflects towards the listener, so the only reflections to really worry about are the first reflections from the side walls. (I consider the walls to be a much bigger deal than ceiling / floor as the floor has a thick rug and the ceiling is further away and nowhere near as reflective as the side walls.

    btw: I found this really interesting, as the English guy (Tony Knight) has a very good summation of both acoustic and digital room correction that he's done on his own room. I will get to measuring things one of these days!

    Last edited by a moderator: Mar 21, 2018
  18. Whatsisnaim

    Whatsisnaim pfm Member

    If your floor has even the slightest flex or spring in it, I would take the opportunity to get down there and reinforce the joists. Either fix new joists along side the existing ones to stiffen them, or maybe support them with some Acro props, which are surprisingly cheap to buy.
  19. martin clark

    martin clark pinko bodger

    if one wanted to do that, the efficient way is *not* to double the joists, but to support a new sub-joist cross-wise underneath, located orthogonal to existing floor joists and along their mid-span line, supported snug though no need to jack-up officiously: because 1/2 the span = 1/8 deflection; effectively ~ 8x the floor stiffness, if you like. Easily &cheaply achieved, in the condition pictured.
  20. Tenson

    Tenson Trade: AudioSmile

    Going back to edit this for clarity, here is my thinking on the subject of the floor.

    There are two factors being discussed here - 1) Standing waves between room boundaries 2) Floor resonance.

    I've yet to listen in the room so it could sound terrible, but I don't buy the idea that suspended floors are nessicarily a problem. What certianly is a problem is solid high mass floor which reflects all energy back to the room creating strong nulls and peaks from standing waves. While a 'soft floor' won't do that to such a degree, what you get in return is a floor with a resonance frequency caused by the mass of the floor on the air cavity spring below.

    I'm also not sure a stiffened wooden floor is a great idea for the above reason. Stiffness will only serve to raise the frequency of resonance. Very little can be thought of as 'stiff' when it comes to sound; everything is elastic and simply have differnt resonance frequencies. Possibly a high frequency resonance would allow damping with less physical depth of absorber.. but this is the point - damping correctly is the key.

    The fact the cavity is 1.3m deep is critical for both the floor resonance and absorption of standing waves.

    The depth of the cavity is related to the floors frequency of resonance, if we can consider it a kinda lossy diaphramatic resonantor. The deeper the cavity, the lower the resonance, hopefully below anything objectionable. With this in mind I don't want a stiff one at all, I want a heavy floppy one sitting on a big hole ;)

    Regarding absorbing standing waves, If it were only 20cm deep it would be little help to fill the void with porus absorber material. Similarly if I laid all the material evenly across the current cavity it would be of little help. The bass absorbers need to be of sigificant physical size comapred with the wavelength of desired absorbtion. The fact each main bass absorber occupies a localised volume of about 570 Liters in each corner (where all standing waves intersect) is what I hope will allow them to damp low frequencies (and damp the floor at the same time).

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