Possible house purchase - family/AV room advice

masopa

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I need some help on whether this setup works and which of the speaker placement options would be best from an acoustics perspective (for both hifi stereo listening and AV purposes).

Ok, we're keen to move and have found a possible house. It benefits from a family room on the bottom of three storeys (which has no other rooms apart from a double garage and a bathroom/drying room). A small cupboard next to the family room could work well as an AV/server hub.

We haven't put an offer in for the house yet, but we're seriously considering it. As part of our diligence process, I want to test out how the family room could be set up as a multipurpose "family" room / AV room combo. It opens out onto the garden so will definitely be an entertaining room, even though the formal rooms (sitting room, dining room) are upstairs and open onto first floor decking. The sitting room won't have a TV in it - it and the dining room will just have a Sonos-type audio player (make/kit to be determined).

So, back to the family room: it's a bit too nearly-square for my liking, especially when we block off the end of the room with heavy curtains - partly to black out the light and partly for acoustic reasons. Hopefully the fact that the rear "wall" is actually sound absorbant curtaining (with dead space behind) helps?

The big issue, though, is speaker placement. I realise in an ideal world, they'd be just slightly closer together than an equilateral triangle would imply. Unfortunately, there's a hulking great door in the way, which means we either end up with them quite far apart (greater than the distance to the listener and a 75 degree angle between them), or move them closer together, the other side of the door, which means only a 35 degree angle between them.

All speakers will be wall-mounted with as sturdy wallmounts as I can manage to find and blend in. We'll be ripping off the wall with the TV/projector on in order to run cables etc and will be doing the same to the ceiling, for lighting and cable runs to the surround speakers. While we're at that, we may as well run additional cabling conduits and cabling for potential ceiling speakers and a rear additional pair of surrounds for 7.1 rather than just 5.1. We might eventually consider a full 7.2.4 Atmos system using our existing sub and perhaps a funky infinite baffle job with drivers in the garage - all fun thinking about it!

The downside is the current flooring is laminate, which is the worst possible. So a large, thick pile rug will need to go down covering as much of the floor area as possible.

Additional acoustic treatment would probably be done on a bit-by-bit basis, using wife-friendly "picture boards", either DIY using a loose-weave canvas covering rockwool boards mounted inside a softwood frame. I think we could get away with beanbag-type corner traps - basically giant beanbag coverings but with cheap hollowfibre duvets inside, instead of closed-cell foam beans. We have young kids, so they'd love to jump on those and we can put them back in the corners when we want "AV time". I'd plan to build in ceiling panels too, possibly even using the void full of rockwool with an acoustically transparent/foam/grill covering for those areas where we won't have lights etc. Plenty of options as we'll be taking off the existing plasterboard.

Below is a diagram of our intented setup, with the couple of options we have for speaker placement. One could suggest swivelling the whole setup around 90 degrees, so the front wall is the fireplace. But, this creates two problems: one with where the centre speaker goes and the consequent height of the screen above the fireplace and secondly with the right wall being curtain (with dead space behind) vs the left wall being conventional. I can't imagine that would lead to ideal acoustics?

Family room.png
 
Edited to add: I've worked some of this out (see bottom para) but not all...

Ok, not really an update as such but I've been experimenting with our current room (living room) and acoustic measurement. I'm using REW to generate a sine sweep from my PC through a cheapo Behringer USB->Optical box (more on that shortly). I then have a similarly cheap Dayton Audio IMM6 measurement mike plugged into my phone with an RTA app recording the peak level at 1/6 octave resolution. When I have a TRRS->PC adapter I'll be able to plug my mike into my PC and simply use REW properly, but it sort of works for now, even though it doesn't give me the res I'd like.

My response curve is below - for my room, which is far from ideal as the AV is crammed into the corner and front-back is basically along the short wall, rather than the long wall of the room. But it's a living room so compromises have to be made:

Freq resp 21-Jul-15.png


A few observations:

1. the roll-off from about 10KHz seems to be related to the output device I'm using - high frequencies don't sound right as its doing the sweep, so I'm going to switch to using USB input directly into my amplifier's DAC (Cyrus 8xpd QX which has a USB input). So I reckon we can get that fixed.

2. The peak at about 100Hz is either speaker-related or mike-related as it appeared when I was doing my calibration runs with pink noise (which, btw, seems to have had no effect!) - I guess it could still be a room mode, but the REW room simulator doesn't seem to suggest so

3. The low point at 300Hz might well be a room mode (out of range of REW sim) although I think that corresponds to a wavelength of just over 1m which isn't really related to any of the room dimensions, obviously?

Of course, the biggie is the awful upward-sloping trendline of the curve as a whole. I know Cyrus amps exhibit a certain brightness but I'm obviously looking for a general trend downwards to follow our natural loudness response across the frequency spectrum.

Any ideas what might be causing that? Is it just poor acoustic treatment or setup? As an experiment, I might see what hanging a duvet against the back wall does to the curve - although not entirely sure how best to rig it temporarily for testing purposes...

As mentioned, this is all really a bit of a dry run before the new house move, but I'm keen to hone my skills now.

Any suggestions or advice welcome. Are upward-sloping response curves "normal" in untreated rooms?

Edited to add: after some considerable experimentation, the low response below 70-80Hz appears to be a strange artefact from my AV amp, a Yamaha. Even after making sure all the LFE out settings are correct, it does not appear to drive my SVS SB2000 subwoofer well (using a line level signal, either from the LFE or directly from the main pre outs). However, when that same main pre out signal is passed into my Cyrus (AV direct mode, i.e. unity gain) and then whipped straight back out again from the pre outs of the Cyrus, this signal - which should be identical - appears to drive the subwoofer perfectly and gives me a 15-20dB increase to the sub 70Hz part of the curve above! Most bizarre... at least I've found part of the solution though :)
 
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Are you altering the output of the amps LFE channel on the Yamaha at all?
 
Not at all - when I use that connection method it feeds straight into the LFE input (=left channel line in) of the sub. Oddly it remains the same problem when I connect the sub with the pre amp out from the Yamaha as well though... the only "solution" is to pass the signal through the Cyrus and then back to the sub!

I forgot to answer your question re: REW... it's Room Equalisation Wizard and a very smart bit of software on the PC. I'm only really using it as a tone generator until a missing cable arrives which will allow me to do full in-house analysis. Critically, it also has a module called the room simulator which allows you to place your speakers and sub in the room (having specified dimensions) and see the room modes / theoretical frequency response at any listening point. Very clever!
 

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