New Studio Build, Hello!

[amac2673]

Hello everybody!

I have been reading here for a while and getting as much info as I can. I have been playing, performing, producing and releasing music for over 15 years in various different home studio configurations. My wife and I just moved into our brand new house in which I had one of the rooms left unfinished so that I could build a sound isolated recording studio!

The room in question is 17x15 and has 9' ceilings with open joists. The floor is a concrete poured slab, three of the walls are outside poured foundation walls that are underground/below grade with the fourth wall being common to the finished recreation room, (the common wall is 17' long).

On the rec room side of this wall is the home theater projection screen with in wall LCR's and 2 AC outlets. I have already redone this wall with double 5/8 drywall and Green Glue, 24" on center framing and putty packs on the back side of the outlets, I am currently boxing the in wall theater speakers in as well.

My goal for this room is to be able to track acoustic drums with little to no noise getting into the house and disturbing the wife or two year old trying to sleep two floors above.

I play/write dance/rock music and tend to get creative after everyone else is going to bed.

My current plan for the space is to build a completely decoupled room within this room using metal studs 24" on center, double 5/8 drywall with GG, insulate the open joist above and attach the interior ceiling to heavier gauged studs spanning the wall caps.

The three poured foundation walls are already insulated and I will insulate the common rec room wall as well as the interior studio walls.

I am trying to figure out if it is worth splaying the walls and ceiling or if treatment will be adequate. I plan on mixing in this room and have been reading about RFZ's, just not sure the best way to go about it in this situation.

For lighting I was thinking some kind of track surface mount type to eliminate holes in the walls and possibly surface mount AC outlets for the same reasoning.

I have done a Sketchup of the space mainly to get an idea of what I can fit in the room and panel locations but seem to be having a hard time getting it to upload to the site, I will keep trying though.

Any feedback or suggestions would be greatly appreciated, I waited a long time to do this and really don't want to get it wrong.

I'm thinking $2000-3000 for material costs and I am doing the construction myself, my family are all general contractors.

Thanks so much,
Allen

[amac2673]

Oh, I forgot to mention that in ceiling across the front of the room where I am planning to put my desk there is a branch HVAC line running perpendicular under the joists, this line is against the wall and extends into the finished rec room, in the rec room it has a soffit around it. I don't think this will be a problem thought as since this is where the mix area will be I can angle the ceiling down and have it go below the branch line.

[Soundman2020]

Hi Allen, and welcome!

The room in question is 17x15 and has 9' ceilings with open joists. The floor is a concrete poured slab, three of the walls are outside poured foundation walls that are underground/below grade with the fourth wall being common to the finished recreation room,

That's an excellent starting point, and it even has a good room ratio. Lucky guy!

On the rec room side of this wall is the home theater projection screen with in wall LCR's and 2 AC outlets. I have already redone this wall with double 5/8 drywall and Green Glue, 24" on center framing and putty packs on the back side of the outlets, I am currently boxing the in wall theater speakers in as well.

Just clarifying here: so the studio is going to be on one side of that wall, and the home theater is on the other side?

Big question: will they both be in operation at the same time? For example, will there be a "crazy gorilla" drummer going wild on the drums in the studio, while someone is trying to watch a soft, quite romantic scene in the home theater? Or the other way around: Will someone be watching a galactic war movie, with earth-shaking bomb explosions and rafter-shuddering cannon fire, while you are trying to track soft, gentle romantic ballad vocals in the studio? If either of these is "yes", then that wall is going to need major attention....

My goal for this room is to be able to track acoustic drums with little to no noise getting into the house and disturbing the wife or two year old trying to sleep two floors above.

OK, so this is a major isolation project then regardless of the home theater issue. "Acoustic drums" is around 115 dB and perhaps more. "Sleeping child" is probably around 30 dB and less. That's some pretty big isolation needs you have there! Especially if you add in the galactic warfare from the home theater at the same time...

My current plan for the space is to build a completely decoupled room within this room using metal studs 24" on center, double 5/8 drywall with GG, insulate the open joist above and attach the interior ceiling to heavier gauged studs spanning the wall caps.

That should get you somewhere in the region of 60-something dB of isolation, if you do it all properly. Is that enough?

I am trying to figure out if it is worth splaying the walls and ceiling or if treatment will be adequate. I plan on mixing in this room and have been reading about RFZ's, just not sure the best way to go about it in this situation.

Question: Is this going to be your livelihood, or just a hobby? Will the studio put bread on the table for you and your family, or is it just a pass-time? If it is your work, and the source of your income, the I would absolutely recommend the full RFZ concept, with soffited speakers and suitable treatment: If it's just a hobby, then that would still be a good thing to do, but not nearly so necessary. So the issue basically is to decide if the control room has to be so good that you can produce finished work that translates really well to all other places, rivaling or exceeding that of your competitors.

For lighting I was thinking some kind of track surface mount type to eliminate holes in the walls and possibly surface mount AC outlets for the same reasoning.

Yes! Very smart move. In fact, for the very high levels of isolation you need, that's the ONLY choice you have. You can't even afford to have the tiniest crack in any part of our studio, where sound could get out.

I'm thinking $2000-3000 for material costs and I am doing the construction myself, my family are all general contractors.

For the type of isolation you are talking about, that is an unrealistic budget. That will barely even cover the costs of your flooring. You have 225 square feet of floor area, so you are basically budgeting US$ 8 to US$ 13 per square foot. But: even cheap laminate runs around US$ 5 per square foot (by the time you including underlay and trim, and allow for wastage), so there's nearly US$ 1,200 gone right there. Drywall costs about US$ 10 per sheet for 5/8" fire-rated. One sheet covers 32 square feet. You have 832 square feet of walls + ceiling, times two (two layers), so that's a total of 1,664 square feet, plus 10% wastage (typical) = 1,830 square feet, divided by 32 = 58 sheets. That's nearly US$ 600, just for drywall. Now add screws, tape, mud, etc. Getting close to a grand there too. That's your entire budget blown on only flooring and drywall, and still no studs, nails, caulk, Green Glue, electrical system, HVAC system, doors, windows, seals, acoustic treatment, or anything else!

Just a pair of acoustic doors could cost your entire budget, if you buy them ready made, and won't be less than a grand, even if you build them yourself. If you want a window in there, there's another several hundred dollars just for the 1/2" and 5/8" laminated glass, without considering the mounting. Even a simple HVAC system is going to cost more than your entire budget, without installation.

I would seriously, seriously re-think your budget. To do it right, to the level of isolation you are talking about, I would add a zero on the end of your estimate. That would be realistic. At the very least, multiply by 5. It just isn't feasible to do all that needs to be done to isolate a studio to high levels on the budget you are talking about.

I'm not trying to be a wet-blanket here, aiming to kill your project or your enthusiasm! Far from it: I'm just trying to point out what I see as a major shortcoming in your plans. Everything else looks fine so far, but the budget just isn't there. You need major isolation to meet your stated goals, and that implies expense. You also need all those other things that you didn't mention, such as HVAC, electrical, doors, windows, floors, treatment, etc. None of that is cheap. Any one of those could take up your entire budget, or most of it. So I would suggest either setting aside more money to do it all now, or if the money isn't there at present, then build it slowly over many months, doing each bit as more funds become available.

Oh, I forgot to mention that in ceiling across the front of the room where I am planning to put my desk there is a branch HVAC line running perpendicular under the joists, this line is against the wall and extends into the finished rec room, in the rec room it has a soffit around it. I don't think this will be a problem thought as since this is where the mix area will be I can angle the ceiling down and have it go below the branch line.

It would really help if you could provide some photos, and also upload that SketchUp model! If it is too big to upload directly, then upload it to a file-sharing service (such as DropBox), and post the link here, as well as a couple of images saved from the model, so people can at least see part of it in the future, even after the DropBox link expires.

It would be really useful to be able to see the room in more detail, both in terms of how it looks now and in your plans for how you'd like it to end up. There might be things that can be done to reduce the costs in some places, for example, or other things that you haven't noticed or considered yet. So please post photos and the SketchUp, as well as any additional info that you happen to think of.


- Stuart -

[amac2673]

Just clarifying here: so the studio is going to be on one side of that wall, and the home theater is on the other side?

Big question: will they both be in operation at the same time? For example, will there be a "crazy gorilla" drummer going wild on the drums in the studio, while someone is trying to watch a soft, quite romantic scene in the home theater? Or the other way around: Will someone be watching a galactic war movie, with earth-shaking bomb explosions and rafter-shuddering cannon fire, while you are trying to track soft, gentle romantic ballad vocals in the studio? If either of these is "yes", then that wall is going to need major attention....

The basement is for the most part daddys domain, and there isn't a galactic war that's more important than daddy making music

That should get you somewhere in the region of 60-something dB of isolation, if you do it all properly. Is that enough?

Does that mean that if I'm playing drums at 115db that 55db of sound will still be audible outside of the studio?

Question: Is this going to be your livelihood, or just a hobby? Will the studio put bread on the table for you and your family, or is it just a pass-time? If it is your work, and the source of your income, the I would absolutely recommend the full RFZ concept, with soffited speakers and suitable treatment: If it's just a hobby, then that would still be a good thing to do, but not nearly so necessary. So the issue basically is to decide if the control room has to be so good that you can produce finished work that translates really well to all other places, rivaling or exceeding that of your competitors.

This is an interesting question as I have recorded and released music professionally as well as had a few record labels and have done remixes for some pretty big dance music artists, currently the studio is not putting food on the table but it could put some cash in my pocket again in the future, my aim is to have a nice sounding room that I can get good translatable sounding mixes out of.

For the type of isolation you are talking about, that is an unrealistic budget. That will barely even cover the costs of your flooring. You have 225 square feet of floor area, so you are basically budgeting US$ 8 to US$ 13 per square foot. But: even cheap laminate runs around US$ 5 per square foot (by the time you including underlay and trim, and allow for wastage), so there's nearly US$ 1,200 gone right there. Drywall costs about US$ 10 per sheet for 5/8" fire-rated. One sheet covers 32 square feet. You have 832 square feet of walls + ceiling, times two (two layers), so that's a total of 1,664 square feet, plus 10% wastage (typical) = 1,830 square feet, divided by 32 = 58 sheets. That's nearly US$ 600, just for drywall. Now add screws, tape, mud, etc. Getting close to a grand there too. That's your entire budget blown on only flooring and drywall, and still no studs, nails, caulk, Green Glue, electrical system, HVAC system, doors, windows, seals, acoustic treatment, or anything else!

I have already priced up the studs, drywall, mud, flooring, lighting, insulation and GG, I am at $2900US. Like I said my family is in construction, I already have screws, tape and the other miscellaneous construction materials at my disposal.

My big concerns are the HVAC and doors, I would prefer to build the doors myself as it looks a lot cheaper and I was planning on building silencers for the vent and returns.

I will take some pics of the space and have been trying to upload a jpg of the Sketchup I did but I keep getting an error everytime I do.

Thanks a ton for the reply Stuart!

Allen

[amac2673]

Every time I attempt to upload any pics I get this error? Can anyone explain?
Just so you know I am trying to upload some jpgs from Sketchup that are within
the guidelines. 700px width.

Error 500
http://www.johnlsayers.com/phpBB2/posti ... =2&t=18680
/phpBB2/posting.php?mode=reply&f=2&t=18680
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:25.0) Gecko/20100101 Firefox/25.0
44
129.2.129.153

Thanks

[amac2673]

Here is what I am thinking, the ceiling above the desk is angled down for both acoustic reasons and the fact that
an HVAC branch line is in that part of the ceiling going across the wall. Everything in orange is treatment and I will
do the same on the transparent back wall.

https://www.dropbox.com/s/r334doik039j4 ... Studio.jpg

[amac2673]

Here is a pic from the back corner of the room, you can see in the ceiling the branch of the HVAC, the reason part of it has been
closed in is because I moved the wall out about 4 feet to make the studio bigger. I am planning on angling the ceiling there as
that will be the mix area. The wall with the speakers is a double 5/8 drywall with GG in between. I am going to box in the speakers
with some 2x8's and I have putty pads for the AC outlets on the Theater side.

[amac2673]

Two questions,

I was looking through some more posts and I saw that John "at least in one post" did not like using metal studs in the studio and preferred 16" OC as opposed to 24" OC spacing? I thought that metal was better for isolation and 24" OC was preferred, am I off on this?

So after a little more digging it appears in a double wall situation that there is no advantage to metal over wood....

Also in regards to HVAC, this room currently has a vent in it, I was planning on putting silencer on that and porting it into the inner room, would a dead vent be a good solution for the return in this kind of situation?

Thanks,
Allen

[Soundman2020]

The basement is for the most part daddys domain, and there isn't a galactic war that's more important than daddy making music

Good to see that your family has their priorities right!

Does that mean that if I'm playing drums at 115db that 55db of sound will still be audible outside of the studio?

Right, as measured in dBC, and assuming that you build it right...

currently the studio is not putting food on the table but it could put some cash in my pocket again in the future,

OK, so currently just a hobby studio, but possibly usable in the future as a money-making proposition. Do keep in mind that if you plan to bring paying customers into your studio in the future, then you might be subject to some of the weird and wonderful laws that are imposed on commercial operations, such as the need for wheelchair accessibility (wide doors, ramps not stairs, grab rails, etc.), tougher fire codes, emergency signage, and exciting things like that...

I would prefer to build the doors myself as it looks a lot cheaper

Yup! That's for sure!

I was planning on building silencers for the vent and returns.

Right, that's the best way to do it, but the materials still cost money. Duct liner, for example, is not cheap, and there are no substitutes. All of your ducts, and all of the silencer box interior surfaces must be fully covered in 1" duct liner. It's all the "little" unexpected things that you keep on running into, that add up.

Every time I attempt to upload any pics I get this error? Can anyone explain?
Just so you know I am trying to upload some jpgs from Sketchup that are within
the guidelines. 700px width.

Not sure what that means! I've never had issues uploading JPGs. Maybe try converting them to GIF or PNG format, and see if that works?

the ceiling above the desk is angled down for both acoustic reasons

OK, but the angle should be at least 12°, just for flutter echo, and probably more if you are going for a true RFZ design.

Here is a pic from the back corner of the room, you can see in the ceiling the branch of the HVAC, the reason part of it has been closed in is because I moved the wall out about 4 feet to make the studio bigger.

Whooa! Yeah, but there's a bunch of issues there with the way the walls are being built! Inner-leaf directly coupled to outer leaf, etc... Stuff that needs fixing.

I am going to box in the speakers with some 2x8's

Are you aware that doing so will totally change the sound of those drivers...? Your Home Theater will sound very different if you box in the back of those just any old how.... that should be done as if you were actually making a proper speaker box. But that's an entirely different subject...

But anyway, to keep your "raging drums" out of the "galactic war" (and vice-versa), that wall is going to need some major beefing up, in addition to correctly boxing in the speakers, and your side of the wall is going to need lots of mass and careful construction too. There are even structural issues with that existing wall, such as the cut stud for the center speaker...

I was looking through some more posts and I saw that John "at least in one post" did not like using metal studs in the studio and preferred 16" OC as opposed to 24" OC spacing? I thought that metal was better for isolation and 24" OC was preferred, am I off on this?

Well, umm... err... the answer is "No, yes, maybe".

The thing is, different frequency ranges are governed by different aspects of the wall. For some frequencies, mass is the key issue, above all others. For other frequencies, rigidity (stiffness) is the governing factor. For still other frequencies, it is the resiliency that matters. And for yet others, it is the damping. Etc. So depending on which post you read by John, Rod, Glenn, me, or someone else, we might have been talking about different aspects for different reasons in different builds.

However, in general, there's a very slight advantage to heavy gauge metal metal studs over wood studs, and a slightly bigger advantage to 24"OC over 16"OC, but only for the MSM part of the spectrum (the part governed by wall resonance). For the very lowest end of the spectrum (the part where galactic wars happen, and also were deep kick drums and 6-string basses live), its the rigidity of the wall that matters most, so 16"OC and wood is better for that...

Hmmm... I think my answers are not helping you much, are they?

Also in regards to HVAC, this room currently has a vent in it, I was planning on putting silencer on that and porting it into the inner room, would a dead vent be a good solution for the return in this kind of situation?

Depends on what you mean by "dead vent". That term has different meanings for different people: Maybe explain in more detail, or provide a diagram?


- Stuart -

[amac2673]

Whooa! Yeah, but there's a bunch of issues there with the way the walls are being built! Inner-leaf directly coupled to outer leaf, etc... Stuff that needs fixing.

What you are looking at in the picture is the existing soffit around the HVAC, the wall was moved 4' out and that soffit around the vent had not been demoed yet. It has been removed up to the wall now, nothing has been done yet as far as building the inner leaf. The inner leaf will be completely decoupled from the outer when I build it.

For the very lowest end of the spectrum (the part where galactic wars happen, and also were deep kick drums and 6-string basses live), its the rigidity of the wall that matters most, so 16"OC and wood is better for that...

Hmmmmm, I do a LOT of dance music and deal with a lot of deep kicks and sub bass, would 24oc wood studs give me the best of both worlds?

Depends on what you mean by "dead vent". That term has different meanings for different people: Maybe explain in more detail, or provide a diagram?

Basically just having another silencer that is not tied into the house HVAC system that is allowing the stale air to vent into another room in basement. I have also read of using this type of vent in order to get fresh air into the studio by just exchanging air from another room in the basement as opposed to actually tying into the main house HVAC as this could prevent possible flanking issues into the whole house since you are not tying into the main house HVAC. Really the HVAC is my biggest issue right now, should I utilize the vent that is already in the room and build a silencer to port the fresh air into the inner room, or should I use a dead vent for both the vent and return in the studio and just exchange air with a adjacent room?

In the second scenario I would have a fan in the vent pulling the fresh air in from the adjacent room, and another fan in the return pulling the stale air out of the studio. Hope this makes sense, I will try and sketch something up soon.

Are you aware that doing so will totally change the sound of those drivers...? Your Home Theater will sound very different if you box in the back of those just any old how.... that should be done as if you were actually making a proper speaker box. But that's an entirely different subject...

Yup, I've been in the residential and commercial AV industry for the past 15 years and am a certified Crestron programmer...

But anyway, to keep your "raging drums" out of the "galactic war" (and vice-versa), that wall is going to need some major beefing up, in addition to correctly boxing in the speakers, and your side of the wall is going to need lots of mass and careful construction too. There are even structural issues with that existing wall, such as the cut stud for the center speaker...

As I said before that wall is a double 5/8's fire rated with Green Glue in between, the studs are 24oc and all of the wall penetrations ie, AC outlets, speakers and switches have been boxed and sealed with acoustical caulk. This wall is not a load bearing structure, the cut stud had not had the box installed yet. My next move is R11 in the stud bays and then I will add double 5/8's with GG between the floor joist above and seal any penetrations with acoustical caulk and install R13.

I have been back and forth on the wall layout though. As you can see in the picture I have that HVAC duct running across the top of what will be the front wall/mix area of the studio, I planned on just making the ceiling angled there to hopefully achieve better acoustics, adding a cloud, corner super chunks, first point reflection absorption and some absorption at the rear wall, possibly a super chunk on the rear wall where the wall meets the ceiling as well if it will help the acoustics.

I have been back and forth on whether it is beneficial to splay the walls or just treat? Given my space what do you think my best option would be?

Thanks again for your help!
Allen

[amac2673]

So I got my Mechanical, Electrical and Building permits today. I have started adding mass to the subfloor above by adding double 5/8s with GG between the joist and will then acoustically seal any gaps. In the picture below you can see the existing branch line coming into the studio space at the front of the room, I am planning on taking the register out and converting it to 8" flex and have that go into a muffler near the bottom of the front wall. I will also build an insulated soffit (pink stuff) consisting of double 5/8s and GG around the existing branch line and have that on the outside of my inner leaf. For the return my thought is to do a passive return on the opposite wall by building another muffler and have it vent into the exercise room that is adjacent to the back wall of the studio. The rest of the basement is already finished and the only return is on the complete opposite end of the house so getting to it is near impossible.

I am planning on angling the inner leaf ceiling down at the front of the room where the mix station will be since I have to go below the branch line soffit anyway.

Does anything sound wrong with what I am proposing to do? Again the inner leaf will be double 5/8s with GG and a double solid core door weather sealed with added mass setup.

Thanks again!
Allen

[amac2673]

Another question,

I have been back and forth on the soffit vs free standing speaker mounting. I currently have JBL LSR28p's which are rear ported so probably not the best for soffit mounting. My dilemma is this, I have never setup a room as well as I am planning on making this room so I do not know that I have ever gotten the most out of my JBL's, they DO have some LF roll off for close to wall placement but I believe it is only around 2db. The question is this, would I be better off buying something like Some KRK Rokit 8's and soffit mounting them or keeping my more expensive JBL's and placing them on some really solid stands and benefiting from the better sounding room? I realize what I am asking is highly subjective but I am curious as to what you guys might do.

I have been reading all over this forum as well as others about soffit mounting and I keep reading about how fantastic speakers like KRK's and Event 20/20's sound when soffit mounted, are speakers such as these going to be better more accurate in the wall than my JBL LSR28p's in a properly treated room?

Thanks,
Allen

[Soundman2020]

What you are looking at in the picture is the existing soffit around the HVAC, the wall was moved 4' out and that soffit around the vent had not been demoed yet. It has been removed up to the wall now,

Aaahhh! OK, that makes more sense.

Hmmmmm, I do a LOT of dance music and deal with a lot of deep kicks and sub bass, would 24oc wood studs give me the best of both worlds?

That would be fine.

Basically just having another silencer that is not tied into the house HVAC system that is allowing the stale air to vent into another room in basement.

That might not be legal. Some building codes do not allow one habitable space to vent directly into another habitable space. There might need to be a proper return vent in each room. Better check your building code for that. But even if it is allowed, it's still not a good idea.

I have also read of using this type of vent in order to get fresh air into the studio by just exchanging air from another room in the basement as opposed to actually tying into the main house HVAC

Right, but there you are using a non-habitable space as the exchange chamber. A place where nobody is every doing anything.

as this could prevent possible flanking issues into the whole house since you are not tying into the main house HVAC.

That's why silencers were invented!

The main reason for using an exchange chamber is for houses that have no existing HVAC system, or where teh existing system is already running at full capacity. It's the easy, cheap way out, but it does mean that you still have to have an air conditioning unit in there, with ventilation to the outside world. The advantage here is that you could use a noisy through-the-wall or window mounted air conditioner, instead of a more expensive split-system, but that's about it. I prefer to do it right, with proper silencers linked to the main HVAC system, if it has the capacity to handle that, or if not then silencer for fresh air / stale air only, plus a mini-split in each room.

Really the HVAC is my biggest issue right now, should I utilize the vent that is already in the room and build a silencer to port the fresh air into the inner room,

That's what I would do, assuming that the HVAC system was designed to handle that room, as well as the rest of the house. An honest HVAC contractor should be able to tell you that. The problem with the above sentence is the second word: "honest"....

I have been back and forth on the wall layout though. As you can see in the picture I have that HVAC duct running across the top of what will be the front wall/mix area of the studio, I planned on just making the ceiling angled there to hopefully achieve better acoustics,

That makes sense to me. You can make that soffit a bit deeper, and put your silencer boxes in there too. Make better use of space.

adding a cloud, corner super chunks, first point reflection absorption and some absorption at the rear wall, possibly a super chunk on the rear wall where the wall meets the ceiling as well if it will help the acoustics.

Sounds about right!

I have been back and forth on whether it is beneficial to splay the walls or just treat? Given my space what do you think my best option would be?

That depends on your design concept. If you go with RFZ (the best), then you pretty much have to splay at least the front few feet of the side walls, as far back as the mix position, generally. But if you choose another design concept, then you could do without. It all depends on how goos you want your room to be!

I am planning on taking the register out and converting it to 8" flex and have that go into a muffler near the bottom of the front wall.

Muffler? Or proper silencer box? You do need pretty major isolation for your build, considering that Han Solo and Darth Vader are just a few inches away, so I'd strongly suggest building proper silencer boxes, and making them pretty massive. And also making sure that all your air paths have enough cross section to ensure slow flow.

For the return my thought is to do a passive return on the opposite wall by building another muffler and have it vent into the exercise room that is adjacent to the back wall of the studio. The rest of the basement is already finished and the only return is on the complete opposite end of the house so getting to it is near impossible.

I would run a proper return duct from the outlet side of your silencer box, across the exercise room, and into
main return duct from the exercise room. Wherever the return vent is from that room, there will be a duct just behind that, so it should be easy to figure out how to attach your return to it. The important part is the silencer.

I have been back and forth on the soffit vs free standing speaker mounting.

If you want the best possible accuracy and least amount of artifacts, then soffit mounting is the way to go.

I currently have JBL LSR28p's which are rear ported so probably not the best for soffit mounting.

Right. You'll need to replace those with something that is front ported nor not ported at all.

JBL's, they DO have some LF roll off for close to wall placement but I believe it is only around 2db.

Theoretically you will need to roll off 6 dB, since that is what the soffit does for you: It restores the power imbalance that was created by having the drivers in a small box, and that power imbalance was exactly 6 dB (half-space radiation vs. full space radiation). However, in practice you might find that 4 or 5 dB is fine. But 2 dB won't be enough, that's for sure.

I have been reading all over this forum as well as others about soffit mounting and I keep reading about how fantastic speakers like KRK's and Event 20/20's sound when soffit mounted,

Personally, I'm a big fan of Adam speakers, and their A7X and A8X do take kindly to soffit mounting...

are speakers such as these going to be better more accurate in the wall than my JBL LSR28p's in a properly treated room?

The basic issue is this: Any time a speaker is placed close to a wall, the sound waves that wrap around behind the speaker will bounce off that wall and then interfere with the direct waves, in several ways: First, you have SBIR, which basically produces a null at certain frequencies at the speaker face itself, which is not good, as well as at the mix position. Then you have comb filtering, phasing issues, first reflections, edge diffraction, and other not-so-nice stuff going on. If you put the speaker IN the wall, then all of that goes away. GONE! If the speaker is mounted so that the front baffle of the little box is exactly flush with the face of the wall, then there is no longer any interaction at all! Firstly, the power imbalance is totally corrected, so the baffle step response circuitry inside the speaker is no longer needed (see above), then SBIR is non-existent, and so are all the other artifacts related to the front wall. They simply are not there any more, because technically, the speaker is no longer in the room at all, and therefore cannot react with the wall. All of the bad stuff goes away, and you are left with just pure, clear, direct sound coming straight at you from the speaker. So you get to hear the speaker exactly as it was designed to sound, without any of the garbage associated with the front wall.

Of course, there's still the other walls in the room, and the speaker does still interact with those, but that's where RFZ design comes in, and treatment. RFZ means that most of the sidewall artifacts can't get to your ears either, and the treatment on the rear wall accomplishes the rest: ensuring that nothing else gets to your ears until after the Haas time (ITDG), and at a level of around 20 dB down from the direct sound. There's still some stuff going in that is unavoidable, especially in small rooms, but that would have been there anyway if you didn't soffit mount, IN ADDITION to all the other stuff.

So basically soffit mounting in an RFZ room gives you the most accurate, cleanest, best sound that your speakers are capable of producing, with minimal artifacts and the least possible coloration from the room itself.

On the other hand, your JBL's would suffer from all of the above problems, since you cannot soffit mount them. So there will be edge diffraction, comb filtering, SBIR, reflections, etc. Even though they are great speakers, all of these issues are simple facts of life, and affect any speaker, to one extent or another.

So my vote goes for soffit mounting, if accuracy and clarity are what you want.

That said, some folks don't like the way soffit mounted speakers sound at first: simply because they are used to hearing all the crap as well as the speakers, so that pure, clean, pristine sound is a bit unnatural at first. Your brain is used to the "crap", and when the "crap" is not there, it sits up a takes notice: something is missing. But when you start doing a bit of mixing, and hear how all the subtle details are just right THERE, crystal clear, in your face, you realize what you have been missing... And when you listen to older mixes that you might have done in the past, you can suddenly hear stuff in there that you never noticed before.

So that's basically the choice.




- Stuart -

[amac2673]

Hi Stuart, thanks for the reply!

So I am leaning heavily towards getting some Adams, I'm not sure whether to go with the 7x's or the F7's though. I have read that the performance differential between the lower priced F7's and the 7X's does not equate to the added expense? Have you or any others had or heard of any experiences with these two different lines?

Unfortunately the exercise room in the basement does not have a return either, there is one return in the finished rec room for the entire basement, so I guess I will have to try and figure out how to get to a return.

If I were to do an RFZ design is the basic rule of thumb that the walls need at least a 12 degree splay between them, meaning that the two side walls would have a 6 degree angle each and the ceiling would need 12 degrees down towards the front wall, and these angles would need to extend past the mix position?

Again my room will be 14x16 with 8' ceilings after the inner leaf is constructed.

As far as that duct that is running across the top wall in the front I was thinking that I should probably build a double 5/8 with GG soffit around it and then build my inner leaf so that the duct soffit is on the outside to better isolate that from the house HVAC system and then just pop a hole in it to run the 8" duct to silencer which will be ported into the inner room.

[amac2673]

So I've been doing some redesigning in Sketchup for the soffit mounted option and RFZ type of construction. I think my design is ok, BUT I am planning on having a 4 piece drum kit in the studio and the way I have it designed right now I am losing 4 feet of space between the desk and the front wall which is just being wasted, this is making it a cramped situation once you add the drums. Currently I have the side walls splayed at 15 degrees and the soffits at 30 degrees. What I really want to do is get the mix position as close to the front wall as humanly or acoustically possible, what would be me best option?

Make the soffits at a 45 degree angle and push them closer to the side walls?

I have read that you 45 is except-able and you do not necessarily need an equatorial triangle between you and the speakers?
I know that in every studio there will be compromises as well, just not sure what to do... Would love some suggestions, I can upload the .skp file too if that would help.

Thanks,
Allen