John Sayers' Recording Studio Design Forum Archive

Hi,


We (me and my 2 friends) got a studio in hour hands, which was built roughly 15 years ago.

The room is ~36 m2

It is located on the top floor of an office building.

We will be using the studio as a producing/mixing studio and recording mostly vocals and occasionally instruments.


The good: the studio is built on a floating concrete floor and is isolated well enough, we have never had any problems with neighbours (even when recording loud bass cabinet and a hard hitting drummer for a week straight from the morning till night).

The bad: the room we use as the control room was originally built to be a recording/live room and it's got no basstrapping but but has got a lot of slats(distance to wall is 5cm) and some places have 5cm glasswool under the slats.
The false-ceiling is ~3meters high and has no acoustic properties ( it's hanging and is made of gypsum, it also vibrates and makes noise at some louder bass frequences) < will throw it out.

The room has many big windows which looks and feels nice but acoustically ? ( probably have to cover one or two to make RFZ?) (also can cover the windows partly or make a diffuser of glass ?)

The room has got bad dips + the bass is not tight at all. ( We just got a behringer measurement mic and I can measure the room next week)

The curren mixing position( on the pictures ) is on a weird spot, but the guys before I got there had put it like that.



I'm thinking about making a reflection free zone + as the ceiling is pretty high (4,55m) I can put up there more than 0.5 meters of wool if neccessary + a fat back wall 0,5m or more insulation under fabric ?

The new mix position we were thinking about is towards the shorter wall which has too large windows( not the glass-doors)






Dimensions: 670X535cm and the real ceiling is 455cm.


I made a sketchup file
I am going to attach some photos, so you could maybe get a better idea, what we are dealing with. ( Sorry for the mess on the pictures)
also a little video https://www.dropbox.com/s/bu2clxzu2i6ma ... n.MOV?dl=0


I really hope I did not forget anything important.

We would like to keep the budget under 5000EUR if possible.


cheers and thanks for any suggestions

Vallo Kikas

The good: the studio is built on a floating concrete floor and is isolated well enough, we have never had any problems with neighbours (even when recording loud bass cabinet and a hard hitting drummer for a week straight from the morning till night).

That's a really good start! Getting good isolation isn't easy, so a large part of your problems are solved with that.

The bad: the room we use as the control room was originally built to be a recording/live room and it's got no basstrapping but but has got a lot of slats(distance to wall is 5cm) and some places have 5cm glasswool under the slats.

It sure does have some strange "treatment"! Those "slats" seem to be an attempt to have some type of diffusion all around the room, with some absorption behind it, but I'd hazard a guess and say that it sounds pretty weird in there... Diffuse mids, but muddy lows, and zingy highs, all at once... but changes depending on where you stand? It looks vaguely like an attempt to produce a poor-man's "My Room" concept, but without understanding the principles!

Are those "slats" wood or metal?

And is that carpet on the floor? It looks like it might be...

Before you start tearing down all of that stuff and re-building the room properly, it would be great if you could do some REW tests in there, to see just what type of response that current "treatment" is producing. I'm intrigued, and curious! You can download REW for free from Home Theater Shack, then use your acoustic measurement mic to run the tests. Post the results here.

The false-ceiling is ~3meters high and has no acoustic properties ( it's hanging and is made of gypsum, it also vibrates and makes noise at some louder bass frequences) < will throw it out

Yup" Smart move! It looks like that was done for aesthetics, certainly not for acoustics.

The room has many big windows which looks and feels nice but acoustically ?

It is possible to have lots of glass in a control room (many of John's designs do), but the room has to be designed correctly to do that. It's not at all clear that your room was designed at all!

(also can cover the windows partly or make a diffuser of glass ?)

A glass diffuser is possible, theoretically, but it would be a real pain to make one, and it would likely be very expensive! If you do want to keep the glass, there are now some transparent micro-perforated foils available that might be useful, to a certain extent. That could be one option, but cost would be an issue.

The room has got bad dips + the bass is not tight at all.

Not surprising! There's practically no bass trapping at all in there, the layout is all wrong, and the entire room is basically just hard reflective surfaces, at bass frequencies.

The curren mixing position( on the pictures ) is on a weird spot, but the guys before I got there had put it like that.

I'm just guessing here, but maybe the reason they left (went out of business?) is because the discovered it was impossible to produce mixes that translate well in that control room... With that asymmetrical layout, no bass trapping, no usable treatment, etc. it's pretty clear that it would be a nightmare to try to mix in there. That will need to be corrected, of course!

I also notice that there seems to be no HVAC in there at all? I don't see any air registers anywhere, and there's that huge noisy portable unit sitting in the middle of the floor... So HVAC is something you will definitely need to do here.

Dimensions: 670X535cm and the real ceiling is 455cm.

It's a decent size room, the ratio isn't too bad (although not ideal), so it has very good possibilities. It could be a good room, but there are a couple of things working against you: mostly, the glass is in the wrong place, and there's not much you can do about it, except cover it up.

What is on the other side of the glass? Are those live rooms? Isolation booths? Offices? Something else? Do you need to see into them?

I see basically three possibilities here:

1) Orient the room the way you show in your SketchUp model, facing the windows, and rebuild the front for proper RFZ, completely covering the glass (or covering most of it). The soffits are going to cover about half of each window as well as the door, so they would not be very usable.

2) Rotate the room orientation 180° so it is facing the blank wall, build a proper RFZ front there, and cover the rear windows with deep, thick bass trapping.

3) Orient the room the way you show in your SketchUp model, facing the windows, but not as an RFZ room: just keep it is a plain rectangular room, and treat it as much as possible.

Options 1 and 2 both mean that the windows on the short wall will no longer be usable, or only partly usable.

Question: Would it be possible to remove the center section of that wall, between the two windows, and just have one smaller window in the middle? That would make a lot of sense..

regarding your layout: there seems to be some confusion there about what the "mix position" is, and what the "38% guideline" is! You have a point marked "mix position" that is 2m from the fornt wall, and another point marked "38%" that is over 2.5m from the front wall!

In a rectangular room, 38% is usually a reasonably good location for your EARS: that's where your head should be, with your ears on the 38% line. And if your head is at that position, and you are mixing with your head there, then you are in the "mix position"! In other words, the mix position is the place where your head is while you are mixing, and that should be set up so that your ears are roughly 38% of the room depth away from the front wall.

A couple of caveats:

A) 38% is not a rule! It's a guideline, a good starting point, that generally works OK for most rectangular rooms, but you should still play around with that and see if you can find a better location. You do that both with your ears, and also with REW and your measurement mic. Start at that point, then move a bit forwards and backwards, to see if there is a spot nearby that has smoother bass response.

B) This is for RECTANGULAR rooms! RFZ rooms, by definition, are not rectangular: there are large, flat, massive, rigid surfaces at the front that very much change the shape of the room. So normal room mode calculators are not accurate, and the 38% rule is not applicable...

On your SketchUp model, you mentioned that you are " thinking about genelec 8351 / 8260" for your speakers: those are great speakers, but not easy to soffit mount! Both of those models are rear-ported, which greatly complicates soffit mounting, and the both have curved shapes, meaning that you'd have a really tough time matching the cutout in your soffit baffle to the shape of the speaker. It's hard enough to do that for some models of Adam speaker, and they only have a single canted surface on each side: cutting a 3D curve in your baffle would be tough to do. Not impossible; just complicated.

I'd suggest going with a speaker that is front ported or not ported at all, and one that has a more rectangular shape. Those are much easier to soffit mount. Adam has some good stuff, but they still seem to be going trough financial, administrative, and logistical problems, and it's not clear if they are going to survive, so I'm not recommending them at present. A good alternative is Eve, which uses the same technology. Focal has some good stuff too. So do Barefoot, Event, and several others. Look around for something that fits your budget, is suitable for that size room, is front-ported or un-ported, and has a roughly rectangular shape.

Overall, I'd say that your room has good possibilities, but the biggest issues are the glass and the door in the wrong place, and the lack of HVAC. Those are the two things that are going to need most attention in the design.

- Stuart -

Big thanks for your tips !

Are those "slats" wood or metal?

The slats are wooden

And is that carpet on the floor? It looks like it might be...

Yes, it's carpet , we will change it to a wooden/laminate I guess

Before you start tearing down all of that stuff and re-building the room properly, it would be great if you could do some REW tests in there, to see just what type of response that current "treatment" is producing. I'm intrigued, and curious! You can download REW for free from Home Theater Shack, then use your acoustic measurement mic to run the tests. Post the results here.

Got the behringer measuring mic and will measure the place next week, as I'm sick and 150km from the place at the moment.

I also notice that there seems to be no HVAC in there at all? I don't see any air registers anywhere, and there's that huge noisy portable unit sitting in the middle of the floor... So HVAC is something you will definitely need to do here.

There actually is but you can't see it from the pictures, there are 2 big pipes for air (diameter 40cm or more)

What is on the other side of the glass? Are those live rooms? Isolation booths? Offices? Something else? Do you need to see into them?

behind the 2 big windows is a " lounge " ,where the secretary is working...that room also got big windows and the sunlight comes to the studio from there, also the view is great, you can see big cruise ships and the port of Tallinn from there

The other window-doors are iso-boxes. The one on the front left from my suggested mix-spot Is a smaller iso-box and it luckily has another door for entrance also, so that one we could cover up.

The one in the back left from my suggested mix-spot is a bigger iso-box(guess it's 3X4 meters, tho I forgot to measure it), that one we would love to keep uncovered.

I see basically three possibilities here:

1) Orient the room the way you show in your SketchUp model, facing the windows, and rebuild the front for proper RFZ, completely covering the glass (or covering most of it). The soffits are going to cover about half of each window as well as the door, so they would not be very usable.

2) Rotate the room orientation 180° so it is facing the blank wall, build a proper RFZ front there, and cover the rear windows with deep, thick bass trapping.

3) Orient the room the way you show in your SketchUp model, facing the windows, but not as an RFZ room: just keep it is a plain rectangular room, and treat it as much as possible.

Wouldn't the RFZ work with sidewalls deadened but the big windows open? I mean If we dampen the sides(like in the sketchup file), ceiling and backwall and make sure no reflections come from the back to bounce from the glass( I know about the speaker omnidirectionality but read somewhere the backwall acts like a false flush mount ? And higher frequencies are directional?!) We were not planning to soffit mount(im aware of the benefits), it would get too complicated if we wanted to sit towards the windows.

Question: Would it be possible to remove the center section of that wall, between the two windows, and just have one smaller window in the middle? That would make a lot of sense..

I guess that would get a bit complicated, I think it's holding up the ceiling partly but I'm not sure, I will ask the other guys who I'm doing it with.

regarding your layout: there seems to be some confusion there about what the "mix position" is, and what the "38% guideline" is! You have a point marked "mix position" that is 2m from the fornt wall, and another point marked "38%" that is over 2.5m from the front wall!
In a rectangular room, 38% is usually a reasonably good location for your EARS: that's where your head should be, with your ears on the 38% line. And if your head is at that position, and you are mixing with your head there, then you are in the "mix position"! In other words, the mix position is the place where your head is while you are mixing, and that should be set up so that your ears are roughly 38% of the room depth away from the front wall.

I know the 38% "rule". The sketchup got a bit messy as the distance from front wall would be 2.5+ meters and we are not willing to buy big mains and was thinking to put the monitors next to front wall and the maximum distance from those monitors would be not more than 2 meters I believe. Leaning towards 8351, which are expensive but 8260 ( which could handle the 2.5 meter distance) is too much I guess.



A couple of caveats:

A) 38% is not a rule! It's a guideline, a good starting point, that generally works OK for most rectangular rooms, but you should still play around with that and see if you can find a better location. You do that both with your ears, and also with REW and your measurement mic. Start at that point, then move a bit forwards and backwards, to see if there is a spot nearby that has smoother bass response.

Yes, will take the measurements asap, I guess we should throw the ceiling out before, as its causing more trouble than good.

On your SketchUp model, you mentioned that you are " thinking about genelec 8351 / 8260" for your speakers: those are great speakers, but not easy to soffit mount! Both of those models are rear-ported, which greatly complicates soffit mounting, and the both have curved shapes, meaning that you'd have a really tough time matching the cutout in your soffit baffle to the shape of the speaker. It's hard enough to do that for some models of Adam speaker, and they only have a single canted surface on each side: cutting a 3D curve in your baffle would be tough to do. Not impossible; just complicated.

I'd suggest going with a speaker that is front ported or not ported at all, and one that has a more rectangular shape. Those are much easier to soffit mount. Adam has some good stuff, but they still seem to be going trough financial, administrative, and logistical problems, and it's not clear if they are going to survive, so I'm not recommending them at present. A good alternative is Eve, which uses the same technology. Focal has some good stuff too. So do Barefoot, Event, and several others. Look around for something that fits your budget, is suitable for that size room, is front-ported or un-ported, and has a roughly rectangular shape.

I guess we'll have to do without soffit mounting.

Overall, I'd say that your room has good possibilities, but the biggest issues are the glass and the door in the wrong place, and the lack of HVAC. Those are the two things that are going to need most attention in the design.

We maybe can change the location of the door. HVAC is covered.


Cheers,

Vallo

Wouldn't the RFZ work with sidewalls deadened but the big windows open? I mean If we dampen the sides(like in the sketchup file), ceiling and backwall and make sure no reflections come from the back to bounce from the glass

That would not be RFZ. The concept of RFZ is that the front wall has several hard, solid, massive surfaces, set up at specific angles in order to force all early reflections past the mix position, thus creating the "Reflection Free Zone" around the engineer's head. That's where the term RFZ comes from. It depends on having those angled front wall surfaces. If you don't have those, then you don't have RFZ. It cannot be accomplished with absorption or diffusion: it does require those angled reflective walls.

That's the first part of the concept. The second part is absorption on the rear wall, to deal with the energy being directed there by those surfaces at the front. If the room is big enough, it might also have diffusion on the rear wall.

The basic goal is to ensure that no reflections arrive at the engineer's ears until at least 20ms after the direct sound gets there, and even then it arrives as a diffuse sound field, at least 20 dB lower in intensity than that direct sound. That's part of the RFZ spec. There are not many ways of achieving that.

I know about the speaker omnidirectionality but read somewhere the backwall acts like a false flush mount ?

The back wall is the one BEHIND the engineer, at the other end of the room from the speakers. The front wall is the one where the speakers are. If you place a speaker close to a wall, that does not make it into a flush mount, unfortunately: if it did, then studios would not spend big money to get their speakers flush mounted! A speaker close to the front wall still suffers from diffraction, comb filtering, SBIR, phasing, and a whole bunch of other artifacts that simply cease to exist in a proper flush mount. About the only thing that you accomplish from placing a speaker close to the front wall is to get a 6dB boost in bass response, due to changing the radiation pattern from full space to half space, thus doubling the power output for low frequencies (below the baffle step response frequency). You get that effect from a flush mount too, yes, but that's only part of it. All of the other artifacts plus the RFZ benefits are what make flush mounting so attractive. Which is why the vast majority of pro studios have flush mounted mains.

And higher frequencies are directional?!

They are, yes. Which is why you need to shape the front of the room, set up the speaker geometry correctly, and properly treat the rear wall. That's how you deal with the issue of mids and highs.

We were not planning to soffit mount

Then how were you planning to implement an RFZ design? Without flush mounting your mains, and shaping the front of your room, how would you do that?

The sketchup got a bit messy as the distance from front wall would be 2.5+ meters and we are not willing to buy big mains and was thinking to put the monitors next to front wall and the maximum distance from those monitors would be not more than 2 meters I believe.

I'm not sure I understand your reasoning at all! Why would you think that you can't use small speakers at distances greater than 2m!? There's nothing at all in the Genelec manuals, or in acoustic theory, that would lead to that conclusion. The Genelec manual makes it clear that the MINIMUM distance is 0.7 m. In other words, your head must be at least 70cm from the front baffle of the speaker, which makes it incorrect to have them on the meter bridge or desktop, as you show in your photos (which is a bad idea anyway, for all speakers, regardless of make, model or minimum listening distance).

The correct distance between the front baffle of the speaker, and your ears, is not a fixed distance: it does not depend on the monitors: it depends on the room. For any given room, there's only a limited range of possible good locations for your head and for the speakers, and those depend almost entirely on the room dimensions and layout, practically nothing on the monitors themselves. There is also the issue of critical distance, which depends almost entirely on room acoustics. As long as your head is closer than the critical distance of the room, then you are technically in the near field. In fact, the term "near field" refers to the room, not the speakers! Many people get confused about this, because they see speakers advertised as "near field monitors" or "far field monitors", but in reality that definitions of what the "near field" is and what the "far field" is, depend on the room acoustics much more than on the speakers. IF you are further away than the critical distance for the room, then you are in the far field and it would be appropriate to use a far field monitor to cover that part of the room. If you are closer than the critical distance then you are in the near field and it would be appropriate to use a near field monitor. The actual distance could vary greatly: for one room, the critical distance might be 3m, while for another room it might be 10m. In your room, at a rough guess it would likely be around 6m or so, so you could certainly use your Genelecs as near-field monitors for practically the entire room: They don't run out of power or definition at 2m! They are usable up to (and beyond) whatever the critical distance happens to be.

So I don't see why your geometry is laid out the way it is: 2m is too close for that room and those speakers. I haven't done the math or figured out the geometry, but my rough guesstimate is that you'd need to be around 2.5m or so away from the speakers to get a decent sweet spot, good sound stage, proper phantom center, good stereo imaging, and usable room response.

Yes, will take the measurements asap, I guess we should throw the ceiling out before, as its causing more trouble than good.

Definitely! That's a big disaster. No need to have that in place while testing. You could do two tests you want "before" and "after" for the ceiling, just so you can see how terrible it is! But yes, the ceiling has to go. It is NOT doing you any favors, and is certainly messing things up.

I guess we'll have to do without soffit mounting.

Then you'll have to do without RFZ as well! It's really hard to get proper RFZ if you don't flush mount your speakers. It can be done, but not with the speakers you are proposing, and not in such a small room. It would also require some pretty careful design, and some major treatment to pull it off. Flush mounting is so much easier, cheaper, and more beneficial.

Why do you not want to use speakers that are more suitable for flush mounting? Or put in more direct terms: if you want RFZ so badly (and justifiably so), why would you not choose speakers that make it easy to do that? Why choose speakers that eliminate the possibility of RFZ, if RFZ is so important to you?

If your heart is set on using only speakers that are unsuitable for RFZ, then that's fine: in that case, you shod switch to planning for a more conventional rectangular room, and plan the layout and treatment for that instead. That's a reasonable alternative, if you don't want the best possible room. It can still be good, and many good studios are just plain rectangular. As long as you modify the design for that, and drop the concept of RFZ, then you can use whatever speaker you prefer. As long as you understand the consequences of that, and are prepared to live with the artifacts of having non-flush mounted speakers, then there's nothing wrong with that.

HVAC is covered.

Then why is there a large portable air conditioned sitting int he middle of the room?

- Stuart -

Many thanks Stuart for being on it with me !

Soundman2020 wrote:Quote:
Wouldn't the RFZ work with sidewalls deadened but the big windows open? I mean If we dampen the sides(like in the sketchup file), ceiling and backwall and make sure no reflections come from the back to bounce from the glass
That would not be RFZ. The concept of RFZ is that the front wall has sever hard, solid, massive surfaces, set up at specific angles in order to force all early reflections past the mix position, thus creating the "Reflection Free Zone" around the engineer's head. That's where the term RFZ comes from. It depends on having those angled front wall surfaces. If you don't have those, then you don't have RFZ. It cannot be accomplished with absorption or diffusion: it does require those angled reflective walls.

That's the first part of the concept. The second part is absorption on the rear wall, to deal with the energy being directed there by those surfaces at the front. If the room is big enough, it might also have diffusion on the rear wall.

The basic goal is to ensure that no reflections arrive at the engineer's ears until at least 20ms after the direct sound gets there, and even then it arrives as a diffuse sound field, at least 20 dB lower in intensity than that direct sound. That's part of the RFZ spec. There are not many ways of achieving that.

Oh, I must have misunderstood, I thought if you eliminate first reflections(putting absorbers to first reflection points), that would make it RFZ, got my infos from here http://realtraps.com/rfz.htm

Soundman2020 wrote:Quote:
I know about the speaker omnidirectionality but read somewhere the backwall acts like a false flush mount ?
The back wall is the one BEHIND the engineer, at the other end of the room from the speakers. The front wall is the one where the speakers are. If you place a speaker close to a wall, that does not make it into a flush mount, unfortunately: if it did, then studios would not spend big money to get their speakers flush mounted! A speaker close to the front wall still suffers from diffraction, comb filtering, SBIR, phasing, and a whole bunch of other artifacts that simply cease to exist in a proper flush mount. About the only thing that you accomplish from placing a speaker close to the front wall is to get a 6dB boost in bass response, due to changing the radiation pattern from full space to half space, thus doubling the power output for low frequencies (below the baffle step response frequency). You get that effect from a flush mount too, yes, but that's only part of it. All of the other artifacts plus the RFZ benefits are what make flush mounting so attractive. Which is why the vast majority of pro studios have flush mounted mains.

I must have messed things up, I meant the front-wall but wrote it according to the speakers (the wall behind the monitors).
I have read that placing the monitors close to front-wall not only boosts the bass but also helps to avoid dips in bass ? the closer the wall the lower the dip caused by sbir ?

Soundman2020 wrote:I'm not sure I understand your reasoning at all! Why would you think that you can't use small speakers at distances greater than 2m!? There's nothing at all in the Genelec manuals, or in acoustic theory, that would lead to that conclusion. The Genelec manual makes it clear that the MINIMUM distance is 0.7 m. In other words, your head must be at least 70cm from the front baffle of the speaker, which makes it incorrect to have them on the meter bridge or desktop, as you show in your photos (which is a bad idea anyway, for all speakers, regardless of make, model or minimum listening distance).

The correct distance between the front baffle of the speaker, and your ears, is not a fixed distance: it does not depend on the monitors: it depends on the room. For any given room, there's only a limited range of possible good locations for your head and for the speakers, and those depend almost entirely on the room dimensions and layout, practically nothing on the monitors themselves. There is also the issue of critical distance, which depends almost entirely on room acoustics. As long as your head is closer than the critical distance of the room, then you are technically in the near field. In fact, the term "near field" refers to the room, not the speakers! Many people get confused about this, because they see speakers advertised as "near field monitors" or "far field monitors", but in reality that definitions of what the "near field" is and what the "far field" is, depend on the room acoustics much more than on the speakers. IF you are further away than the critical distance for the room, then you are in the far field and it would be appropriate to use a far field monitor to cover that part of the room. If you are closer than the critical distance then you are in the near field and it would be appropriate to use a near field monitor. The actual distance could vary greatly: for one room, the critical distance might be 3m, while for another room it might be 10m. In your room, at a rough guess it would likely be around 6m or so, so you could certainly use your Genelecs as near-field monitors for practically the entire room: They don't run out of power or definition at 2m! They are usable up to (and beyond) whatever the critical distance happens to be.

So I don't see why your geometry is laid out the way it is: 2m is too close for that room and those speakers. I haven't done the math or figured out the geometry, but my rough guesstimate is that you'd need to be around 2.5m or so away from the speakers to get a decent sweet spot, good sound stage, proper phantom center, good stereo imaging, and usable room response.

Thanks for clearing that up The plan I did were the 1st ideas that came to my mind, it doesn't have to be like that. So you say the distance from speakers, is it the front baffle of the speaker or front the wall you mean ? As 2.5m is 38% from the front wall.

Soundman2020 wrote:Then you'll have to do without RFZ as well! It's really hard to get proper RFZ if you don't flush mount your speakers. It can be done, but not with the speakers you are proposing, and not in such a small room. It would also require some pretty careful design, and some major treatment to pull it off. Flush mounting is so much easier, cheaper, and more beneficial.

Why do you not want to use speakers that are more suitable for flush mounting? Or put in more direct terms: if you want RFZ so badly (and justifiably so), why would you not choose speakers that make it easy to do that? Why choose speakers that eliminate the possibility of RFZ, if RFZ is so important to you?

If your heart is set on using only speakers that are unsuitable for RFZ, then that's fine: in that case, you shod switch to planning for a more conventional rectangular room, and plan the layout and treatment for that instead. That's a reasonable alternative, if you don't want the best possible room. It can still be good, and many good studios are just plain rectangular. As long as you modify the design for that, and drop the concept of RFZ, then you can use whatever speaker you prefer. As long as you understand the consequences of that, and are prepared to live with the artifacts of having non-flush mounted speakers, then there's nothing wrong with that.

I must have known the definition RFZ all wrong, I thought it to be just first reflections dampened. I must have caused a lot of misunderstanding with it.
It doesnt have to be RFZ design now when I get what it means. If the room wasn't as complicated, I wouldn't hesitate the RFZ design (angled walls and all that)

What would be your suggestions to make it a good rectangular room ?

Soundman2020 wrote:Then why is there a large portable air conditioned sitting int he middle of the room?

haha, it's because the owners of the building shut the ventilation down @ 8pm and sometimes we need to work there longer

I also added a clean sketchup file if you may want to take a look at it,, it doesnt have all the confusing elements in it.

(English is not my first language, thats why we probably have had some misunderstandings also)
Cheers !

Oh, I must have misunderstood, I thought if you eliminate first reflections(putting absorbers to first reflection points), that would make it RFZ,

That helps, but does not make it a true RFZ design.

got my infos from here http://realtraps.com/rfz.htm

Weellll... yes, but the info on that site is not complete. It is basic, and partly correct, but lacking. In fact, the first photo of a studio in that thread (with the caption "Studio by Wes Lachot Design") shows a true RFZ design, with soffited speakers and angled walls. And that room does NOT use the concepts mentioned in the article! Which is rather strange... Almost all of Wes Lachot's designs are RFZ, or close to RFZ. And as you can see, his rooms are NOT rectangular and do NOT use absorption on the first reflection points...

RFZ is actually a trademarked design. The trademark is owned by the RPG company (manufacturers of acoustic treatment). The design calls for a very specific set of conditions. The problem is that a lot of people do not really understand that, and refer to any room as RFZ if there is some treatment in it that reduces early reflections! But to be a real, true, correct RFZ design, the front walls do need to be angled, and the speakers pretty much always need to be flush mounted.

If you google "what is RFZ studio design" you get this:

https://www.google.cl/search?q=what+is+ ... 42&bih=466

Which shows many rooms that really are correct RFZ designs, as well as some that are not....

I have read that placing the monitors close to front-wall not only boosts the bass but also helps to avoid dips in bass ? the closer the wall the lower the dip caused by sbir ?

Correct. It doesn't prevent SBIR dips: it just moves them to a higher frequency, in the low-mid range, where they are not as noticeable, and are less objectionable. That's why the recommendation is to have the speakers at least 2.5 m away from the walls if the room is big enough, since that puts the SBIR artifacts below the cut-off point for most speakers. That's the second-best location for speakers. If the room is not big enough for that, then the third best location is tight up against the front wall. The best location, of course, is to have the speakers flush-mounted in the walls, so that there is no SBIR at all.

So you say the distance from speakers, is it the front baffle of the speaker or front the wall you mean ? As 2.5m is 38% from the front wall.

Ahhh! OK, I think I see where your confusion is coming from! The 38% measurement is with respect to the front wall of the room. The 2.5 m distance is with respect to the front face of the speakers. But neither of those is a "rule"!!! Just a guideline. As you probably know, the best location for speakers is to have them about 28% of the room width away from the side walls (also not a rule! just another guideline), and that is what will determine how far apart the speakers are: if the room is big, then will be far apart. If the room is small, they will be close together. The distance that they are from each other is also ROUGHLY the distance that your head should be away from the speakers, in order to get a proper "triangle" (which is also not a rule! Yet another guideline!...). So if you have a wide room, and your speakers end up 3m apart, then your head should be about 3m from each speaker, AND ALSO about 38% from the front wall. For a room with good proportions, that would mean that the speakers are angled inwards about 30°, but that 30° angle is ALSO not a rule!!!!

In other words, there's a lot of compromise that goes on in determine the best location, distance, and angles for speakers, and all of those depends on the dimensions and acoustic treatment of the room. All of those "rules" are just rough numbers that give you a situation that won't be bad, should be good, but might not be the best. If you start with that arrangement, you should then experiment a bit to see if you can find a better arrangement. I normally do that by moving the mix position (your head / measurement mic) a few inches forwards and backwards, and testing that, then if I find a better position I try moving the speakers a bit left/right and angling them a bit more/less, to see if that improves even more. Then repeat the whole process. I normally find that I end up with the mix position a bit closer to the front wall, and the speakers angled LESS than 30°, so the apex of the "triangle" is behind the engineer's head. That seems to work well for most rooms.

I must have known the definition RFZ all wrong, I thought it to be just first reflections dampened. I must have caused a lot of misunderstanding with it.

Yeah, that happens... some people think that RFZ is just putting absorption on the walls, but it's a lot more than that. It's a technical specification, laid out by D'antonio and Cox, if I recall correctly, and later trademarked by their company RPG. So from a legal point of view, we designers should not call a room that we design "RFZ" because they own the trademark, but we can say that it is based on the concept of preventing / controlling early reflections arriving at the mix position.

What would be your suggestions to make it a good rectangular room ?

The same basic concepts still apply: First, make sure that the dimensions of the room produce a good ratio (within the Bolt area, at least, and hopefully close to one of the really good ones), then set up the mix position and speakers as I outlined above (I have written more complete procedures in several other threads), then put large bass traps in as many corners as you can, then put thick absorption across the entire rear wall, then put thick absorption on the first reflection points, with a hard-backed angled cloud at the front of the room if possible. Then do a REW test to see what else needs doing, and continue adding treatment until the room is as good as it can be.

it's because the owners of the building shut the ventilation down @ 8pm

That's not good! If you plan to work after that (and MANY studios do...), then you really should consider installing your own HVAC system, independent of the building system.

(English is not my first language, thats why we probably have had some misunderstandings also)

No problem at all! Your English is pretty darn good, actually!

- Stuart -

Thanks for clearing many things up.

I'm speaking hypothetically, I'm adding a picture of the room a little re-arranged: lost the 2 big windows and put the window-door instead of it, in the middle of the short wall. Also lost the door in the right as the door-window could now be used for entrance.

Could it be a true RFZ room now if we angled the walls or would the door-window still be a problem ? (I have Dynaudio BM15 Passives collecting dust)

Soundman2020 wrote:Quote:
it's because the owners of the building shut the ventilation down @ 8pm
That's not good! If you plan to work after that (and MANY studios do...), then you really should consider installing your own HVAC system, independent of the building system.

This we may be able to fix, not sure yet.


Do you also happen to have any good ideas for the ceiling ? Should the whole ceiling be a big trap ? maybe 0.5 meters thick or more ? Or take care separately of the upper corners wall-ceiling-wall corners and wall-ceiling corners ?

Are we good regarding to the calculation ?
Cheers and thanks !

I'm speaking hypothetically, I'm adding a picture of the room a little re-arranged: lost the 2 big windows and put the window-door instead of it, in the middle of the short wall. Also lost the door in the right as the door-window could now be used for entrance.

Could it be a true RFZ room now if we angled the walls or would the door-window still be a problem ?

Yes, that certainly could be made into an RFZ room. Just build soffits that fit in between the central window and the corners, and angle them suitably. You might need two angles on there: one for the soffits themselves, plus an extra panel at a different angle, to connect that to the side walls. That would work.

I have Dynaudio BM15 Passives collecting dust

They would work fine for that. Those are pretty decent speakers, and several forum members are using them in their rooms. They can be flush mounted just fine.

Do you also happen to have any good ideas for the ceiling ? Should the whole ceiling be a big trap ?

You could do that, yes. I would suggest putting a series of acoustic hangers up there (Tom Hidley style ceiling), and putting an angled hard backed cloud above the front part of the room. That should help greatly with bass control, early reflections, and modal damping.

maybe 0.5 meters thick or more ?

Perhaps, but I would model it in SketchUp and do some calculations, to make sure it is going to work.

Are we good regarding to the calculation ?

Yep!

- Stuart -

Thank you! I will write back when I have measured the space.

Hey!

I got a chance to measure the room now.

I measured from 2.5meters from the front wall, speakers in equal triangle. Speakers 5-10 cm from the front wall and 1.2 meters from the side walls.

What do you think of it ?
I am not very good at reading the REW files ( I can read the spl data but the decay times are a bit fuzzy for me).



I dont know why but I can not upload the rew file here, even when zipped, so I put it in my dropbox.
https://www.dropbox.com/s/1oyiam3rbe4q2 ... t.zip?dl=0


( there is something wrong, here, I can't even upload plain images )

I dont know why but I can not upload the rew file here, even when zipped, so I put it in my dropbox

That's fine! The forum doesn't allow files over a certain size, or with certain extensions, so it is better to put them some place like Dropbox.

there is something wrong, here, I can't even upload plain images

There was a problem with the forum yesterday, and some image posting was messed up. But it should be OK now, so please try again.

What do you think of it ?

Ummm.... wellll.... Basically, it is a huge mess! I'm looking at the data now, and I have to say that it is worse than I expected. There are some rather unusual things going on there, with wild variations in room response across the entire spectrum, not just in the low end. That room is going to need some major surgery to make it workable...

- Stuart -