Gyprock vs brick rendering

[Paul Spencer]

The most difficult rooms I've tested in the bass region are also the most solid, with concrete floor, rendered double brick walls and concrete ceiling. If your room is build like a cave, it will sound like one. These rooms need the most treatment. If you have a concrete floor only with brick veneer walls and otherwise conventional stud/plasterboard construction, that's very different.

 

In considering plasterboard vs rendered brick, the main issue typically is bass. Here plasterboard is the better solution, provided that you don't have rattles and insulation is important. This will help with your single biggest and most difficult to resolve problem - bass. In many rooms with conventional light construction, you can get good bass without bass traps. Above the bass range, you can easily treat either solid brick or plasterboard. By contrast, in a cavernous room your problems will extend beyond the bass into the low midrange.

[dcathro]

Mike & Paul,

 

I stand by my opinion that solid rooms are better for audio.

 

My room in London was a "cave" With solid walls and floor, and is the best sounding room I have been in. Admittedly it was professionally treated with absorption and diffusion.

 

I lived in the UK for 16 years, and became accustomed to solid British rooms, with thick carpet, and heavy drapes and furnishings. I found it far easier to get acceptable sound in them than in Australian rooms that leak the bass and reflect back the mids and highs.

 

It doesn't surprise me that most audiophiles run subs to try and compensate.

 

Cheers

 

David

[almikel]

The band practice rooms we rehearse in typically have block walls, slab floor, and foam/carpet on the walls.

they sound boomy in the bass end with lots of overhang/ringing with the top end chopped out - basically terrible.

Compare the practice rooms with my listening room and the difference is significant.

The bass in my listening room is tight and clean with no overhang.

I use a sub for extension and "weight" in the bottom octave, not because I'm compensating for leaky bass.

 

Technical issues have meant my sub hasn't been working for a few months now, but dialing a chunk of low eq on my mid bass drivers is sounding pretty good so I've been too lazy to sort the sub issue (18" mid bass and reasonable power provides some flexibility).

 

If I moved my rig into any of the practice rooms we use, (with or without the sub), achieving a similar bass response would likely require tuned pressure traps  and a lot of absorption (or an inner skin of light weight gyprock on furring channel with insulation behind to manage below 100Hz and reasonably sized absorption to manage freq above).

Reverb times in small rooms aren't necessarily valid but they sure show the extended "hang" time below 100Hz of a rigid room compared with light construction.

 

cheers

 

mike

 

 

 

 

[almikel]

On 2/20/2017 at 11:05 PM, dcathro said:

 

 

I lived in the UK for 16 years, and became accustomed to solid British rooms, with thick carpet, and heavy drapes and furnishings. I found it far easier to get acceptable sound in them than in Australian rooms that leak the bass and reflect back the mids and highs.

 

 

There's no doubt that modern homes with tiles, glass and lots of other hard surfaces need some absorption in the top end also - but that's easy to treat as you say with drapes, carpet (or rugs) and soft furnishings.

 

YMMV - but being a bass nut I always focus on managing the bass first, which IME, is much easier in a leaky room.

(edit) in a leaky room (end edit) a few bands of EQ cut can work wonders below 100Hz or so and "not ridiculous" sized absorption cleans up the 80 - 250Hz range.

Depending on placement, the absorption may also be fixing mids and highs at the same time.

 

If starting with a concrete bunker or cave, achieving low reverb times for bass frequencies is much much harder.

 

cheers

Mike

 

 

 

 

Edited March 8, 2017 by almikel
clarification

[Primare Knob]

What about a combination of the two?

 

I am planning on a room myself that has double brick walls (internal and external) on a concrete slab. In the rest of the house we have put plasterboard up against the bricks using plaster cement, but I am not sure to take the same approach for my HT room. None of the rooms are very sound proof, probably due to a lightweight ceiling and leaky doors and windows.

 

As mentioned by @Peter the Greek depending on what you are after you will have to start with sound proofing first before acoustics.

[almikel]

5 hours ago, Primare Knob said:

 

As mentioned by @Peter the Greek depending on what you are after you will have to start with sound proofing first before acoustics.

Depends on what you want to achieve - if you want good isolation and good acoustics inside the room then start with isolation/sound proofing.

 

It appears that you have solid walls already

5 hours ago, Primare Knob said:

I am planning on a room myself that has double brick walls (internal and external) on a concrete slab.

but minimal sound proofing

5 hours ago, Primare Knob said:

None of the rooms are very sound proof, probably due to a lightweight ceiling and leaky doors and windows.

as you say, likely due to sound going through lightweight ceilings, leaky doors/windows etc - but also sound going around boundaries - known as "flanking" noise - any time there's not an airtight seal you will get flanking noise passing through it.

 

@Peter the Greek is vastly more experienced than I am on achieving isolation and good "in room" sound - achieving both is hard and costly.

 

5 hours ago, Primare Knob said:

In the rest of the house we have put plasterboard up against the bricks using plaster cement, but I am not sure to take the same approach for my HT room.

This would be a very bad approach for a listening room (stereo or HT) assuming you'd like the room to have good bass response with as little treatment as possible.

Leaving isolation/sound proofing aside for the moment, and assuming rigid walls/floor, you need some compliance in the room to soak up/let through bass below 100Hz or so to stop it remaining in the room to bounce around.

 

Lightweight Gyprock does this very well, as long as it's not glued to brick.

In your case I would consider using furring channel mounted on the brick with lightweight Gyprock and insulation behind the Gyprock.

 

Don't use multiple layers of Gyprock and Greenglue in your situation - you have brick to provide isolation - look very closely at flanking noise if isolation is a requirement.

Multi layers of Gyprock/Green Glue are for isolation - not for good "in room" sound - I measured a custom room that had multi layers of Fyrecheck with Green Glue - it sounded and measured like a reverberation chamber.

 

If isolation/sound proofing is a requirement then an airtight "room within a room" is needed.

If isolation is not such a big deal, then lightweight gyprock on furring channel with fluffy insulation behind is the go.

 

You'll still need treatment inside the room - but way less than if you had solid brick walls.

 

cheers

Mike

 

[Primare Knob]

When building for improved in room bass responds does that automatically mean sacrificing sound proofing?

Is a combination of the two possible without a room inside a room approach? For example I have a room with 3 walls being double brick and the back (double brick) wall is being replace by a stud wall. Timber stud flat roof ceiling needs sound proofing treatment. Could either of the non brick constructions being used to let the bass "escape" without sacrificing sound proofing?

 

Does using channels and green glue in combination with Gyprock have the same effect as building a brick wall?

[almikel]

On 3/11/2017 at 3:07 PM, Primare Knob said:

When building for improved in room bass responds does that automatically mean sacrificing sound proofing?

 

turn that question around - when building for sound proofing does that automatically mean sacrificing in room bass response?

The answer is no - but building for sound proofing (isolation) means stopping sound getting through which generally means more sound kept inside the room and the sound energy has to go somewhere to stop it reverberating inside the room.

It's primarily an issue for bass, as higher frequencies are more easily managed/trapped (eg curtains absorb treble).

Sound proofing and good in room bass do work against each other, but both can be achieved - but it does cost more.

 

On 3/11/2017 at 3:07 PM, Primare Knob said:

Is a combination of the two possible without a room inside a room approach? For example I have a room with 3 walls being double brick and the back (double brick) wall is being replace by a stud wall. Timber stud flat roof ceiling needs sound proofing treatment. Could either of the non brick constructions being used to let the bass "escape" without sacrificing sound proofing?

 

I assume your back double brick wall is being replaced because you want to move the wall to make the room bigger? It would be crazy to knock down a double brick wall just to put up a stud wall in the same place.

 

Using techniques such as double stud walls and multiple layers of gyprock/sheeting with green glue (and taking care with flanking noise) does provide excellent sound proofing, but again, multiple layers of gyprock and green glue increases the rigidity and mass (compared to a single layer of gyprock) and will reflect more sound energy back into the room than a single layer of gyprock (but less than a double brick wall).

 

On 3/11/2017 at 3:07 PM, Primare Knob said:

 

Is a combination of the two possible without a room inside a room approach?

 

Not without losing a lot of real estate inside the room - stopping sound getting out and in and absorbing sound inside the room needs rigidity/mass/air sealing to stop the sound getting in/out and then something to absorb the sound inside the room.

A concrete bunker can be made to sound good - but lots of absorption and tuned membrane/pressure traps would be required.

Line that concrete bunker with furring channel or studs, lightweight gyprock and fluffy insulation behind, and you'll lose a little real estate, but much less real estate than treating the naked room with absorption and tuned membrane/pressure traps.

The lightweight gyprock acts as a room sized membrane trap, significantly reducing in room low bass issues.

In this case the concrete bunker is assumed to have good isolation - so the inner skin was all about soaking up low bass, not isolation

 

On 3/11/2017 at 3:07 PM, Primare Knob said:

Could either of the non brick constructions being used to let the bass "escape" without sacrificing sound proofing?

 

 

If you have options with roof height on the new section, that will provide the best options for sound proofing and bass absorption - @svenr posted a thread ages ago where the "ceiling" was cheap vinyl flooring ("lino") with fluffy insulation above that. The vinyl created a large "limp mass" membrane trap for the room requiring little additional treatment.

A sound proof ceiling could be constructed above that (hence my point above about your options on roof height).

Again this involves a room within a room (or 2nd ceiling).

Much easier to create a ceiling bass trap if isolation is not a requirement.

 

There are several people on this forum that I've come to respect their views regarding your particular challenge:

• @Peter the Greekhas great practical knowledge of achieving sound proofing and good in room sound
• @svenr has posted great information on budget approaches to achieving good in room sound without resorting to products with "sound" in their name
• @Paul Spencer - needs no introduction on SNA - but some consulting spent with Paul is likely well spent (I have no commercial connection with Paul, but have purchased his speakers and learned a lot from his posts/blog/emails)

No question that achieving both sound proofing and good in room sound at the same time is harder than either on it's own - and it will cost more.

Good design up front is critical - especially for sound proofing.

 

Best wishes for your project.

 

cheers

Mike