Tall rack on the back wall, compromise acoustics for funcionality?

[EduardoApolonia]

I'm thinking of installing a rack 4x28u on the backwall of the Control room.
I know that it isn't the best place acoustically but functionally I think it's the best place.

Position similar like in these (famous) pics:









I'm tired of tuning outboard EQs and compressors on the racks that are below the console, on the console's top racks that are outside the monitor range, on the side racks that are to the side and in my case low 14U racks.

Most of the time I'm tuning gear that is way outside the listening position.

Wouldn't it be better to have the gear on the back wall where, although not being the listening position it's a better place to listen than any other spots I've said above where I have my racks?

I know I'll lose (in my case) the direct absorption of the mid/high frequencies of the bass trap on the back wall, but in functionality it would be way better for me, and maybe the rack gear would act as a diffuser

Since I would let the bass trap and install the rack on front of it I think that the absorption of low freq would be almost the same.

FYI this is my back wall:
(The right rack on this pic will be removed if I install the back wall rack)




After I move the console a bit closer to the front the back rack gear front plates would be +/- 2,1mt (7ft) from my head when I'm in the listening position. Would this be very bad thinking about the sound reflections from the gear on the back?


Anybody went this route or has any good opinions to share about it? It would be greatly appreciated

[Jens Eklund]

The best approach is to measure and using the ETC to monitor that the placement of racks (or other objects) does not reflect energy back to the sweet spot within the ISD-gap.

[EduardoApolonia]

I know it would be the best way, the problem is that I don't have the racks. And I will only buy them if I decide to go that route. That's why I'm trying to get some opinions before I decide to make the move.

[DanDan]

Many back racks in big studios are kept low to avoid the reflection problem.
If you do put racks back there you could angle them so that reflections would be directed into the side wall absorbers.

DD

[jhbrandt]

Originally Posted by DanDan

Many back racks in big studios are kept low to avoid the reflection problem.
If you do put racks back there you could angle them so that reflections would be directed into the side wall absorbers.

DD

+1

Do I need to add that copying what you have seen done elsewhere is a bad idea?

Photo #1; notice that the racks are in flight cases on wheels and that room was NOT designed that way. - either the tracking engineer(s) rolled those in or the photographer did. The racks block the nice QRD on the back wall.
Photo #2; again racks in flight cases with rollers... your guess is as good as mine. But note that these racks at all vertical. IF they were actually used in this position for critical mixing, most of the reflected energy would be directed toward the floor.
Photo #3; Now this is a real mess... he can't get to the faders on the left side of the console. But note again that the towers of crap behind the mix position are vertical & not slanted back.

Don't slant the racks backwards for better viewing as this will only cause the reflections to go back to the operator position.

Cheers,
John

[Max Dread]

Wow, OMG and thank God for DAWs and plug-ins! Sorry for the irrelevant post...... just couldn't quite believe my eyes. Is the hardware like Gremlins - does it just keep multiplying when you add water? Not that I'd recommend adding water!!!

How many "U"'s of rack gear do you have? Do the units on the side walls have wheels? If not, how about sticking with side walls, adding wheels so that they can be pulled in a bit when in use, and perhaps configuring (if you have not done so already) so that the most often tweaked units are in the most accessible positions?
Sorry if I'm teaching my grandmother to suck eggs here (what ever that means). Just thinking out loud.

Good luck!

[EduardoApolonia]

Originally Posted by DanDan

Many back racks in big studios are kept low to avoid the reflection problem.
If you do put racks back there you could angle them so that reflections would be directed into the side wall absorbers.

DD

That seems to be a good idea, thanks for suggesting it, that will make me definitely abandon the idea of buying a 4bay rack, I was already inclined do buy 2x2bay or 4x1bay.

The only problem I see on that is that if I angle them a bit the sound will go most likely to the side windows and then back to me.

Originally Posted by jhbrandt

+1

Do I need to add that copying what you have seen done elsewhere is a bad idea?

Don't slant the racks backwards for better viewing as this will only cause the reflections to go back to the operator position.

Cheers,
John

It's not a case that I've seen these guys studios and decided to do the same, it's more the other way around, I had an idea of what would be better functionally and searched for examples of what I had on my mind. But if they're making the records they've been doing in these conditions, I don't think it'll be the biggest of my problems

Way worse is the f*%&ing 15db 100Hz dip SBIR problem I have in my studio that I didn't solve yet

Originally Posted by Max Dread

How many "U"'s of rack gear do you have? Do the units on the side walls have wheels? If not, how about sticking with side walls, adding wheels so that they can be pulled in a bit when in use, and perhaps configuring (if you have not done so already) so that the most often tweaked units are in the most accessible positions?

I have about 150-200Us of rack gear. I'm a real collector/gearslut before engineer
I want to have 8 guitar amp heads fixed on the control room for my reamping service that is growing quickly, besides 4 amps I have on top of a 2bay 14U rack I usually have guitar amps laying around on the CR floor and on top of stools, it's a real mess.
You can see it on this pic:



So I was thinking of swapping the 2bay with the 3 bay to get 2 towers of 4 amps on top of it.

I could put on the side walls, but only on one side because on the other side I need the guitar amp heads, so the rack has to be lower.

[jhbrandt]

Originally Posted by EduardoApolonia

...But if they're making the records they've been doing in these conditions, I don't think it'll be the biggest of my problems

True. I am always amazed at what an excellent engineer can do in a terrible room. But the point of proper placement and room treatment is to reduce the time and fatigue burden in order to 'get the job done' quickly.

Originally Posted by EduardoApolonia

Way worse is the f*%&ing 15db 100Hz dip SBIR problem I have in my studio that I didn't solve yet

Have you tried pushing the speakers right up to the wall?? - so that they are nearly touching the wall? - you may need to roll off some bass after that, but it will be a 'steady-state' issue and you can use EQ to correct the LF bump.

Originally Posted by EduardoApolonia

... I want to have 8 guitar amp heads fixed on the control room....So I was thinking of swapping the 2bay with the 3 bay to get 2 towers of 4 amps on top of it. - I could put on the side walls, but only on one side because on the other side I need the guitar amp heads, so the rack has to be lower.

That sounds like a plan... I love your collection. Use REW or similar software to get an impulse measurement after you place the equipment & adjust the position and angles to obtain the best response.

Cheers,
John

[spice house]

DAMN!!!! now those are some SLUTS!!!

[EduardoApolonia]

Originally Posted by jhbrandt

Have you tried pushing the speakers right up to the wall?? - so that they are nearly touching the wall? - you may need to roll off some bass after that, but it will be a 'steady-state' issue and you can use EQ to correct the LF bump.

That is my plan after I take the front basstrap out.
The basstrap doesn't absorb the problematic frequency and since it is about 50-80cm (it's angled) from the wall, it doesn't let the speakers to be moved very close to the wall.

Here you can see pics with and without basstrap.

Bass trap structure



Bass trap 1st fill (loose rockwool batt)


Basstrap 2nd fill (Rockwool panels)


Finished


Here is a plan for you to have a better idea:


This is what I'm thinking of doing to get the speakers closer to the front wall

Originally Posted by jhbrandt

Use REW or similar software to get an impulse measurement after you place the equipment & adjust the position and angles to obtain the best response.

Cheers,
John

The problem is that I don't have the racks yet, I'm trying to be sure that it is a good move before I buy the racks.
Maybe I can put a large wood panel where the rack gear front plates will be to measure it. Would that be a close idea, or being wood instead of the metal faceplates it will be completely different?

Thanks for the suggestions

[jhbrandt]

Eduardo,

Your traps are angled at 30 degress.. this is good... simply position your speaker IN the traps.. You'll need to build an enclosure for the speakers to sit in (decoupled on Sorbothane or Neoprene) and then make a flush mount panel surface on the front of the traps. The flush mount panel will need to be as massive as possible. I recommend 2 layers of 3/4" (2cm plywood). The flush plane needs only be a little taller than it is wide.
Have a look at the Genelec docs...
Note: do not simply put them in the traps without the flush mount panel.
Cheers,
John

[ritelec]

Eduardo,

I believe it was your studio build I was following a couple years back........

Some place you got there !!! Very nice !!!


jhbrandt,

"Just" constructing (framing and filling built wall) will help prevent LF SBIR's.

Flush speaker to wall sealed (how would one vent speakers containing heat sinks ???)

The Genelec in-wall is constructed of masonry???

-rich

[DanDan]

Seems like a shame to deconstruct and then do a major construct. There may be options.
Eduardo, are you fully sure that 100Hz dip is caused by the front wall?
How deep are those traps?
How deep and what density is the front layer of rigid fibre?
I suspect such a trap with mixed densities is probably not as efficient as a simple thick layer.
You could try that.
If there is not enough improvement, change the fronts to slats or perf. Tune it to your problem frequency.
Slats tend to look good.
DD

[EduardoApolonia]

Originally Posted by jhbrandt

Eduardo,

Your traps are angled at 30 degress.. this is good... simply position your speaker IN the traps.. You'll need to build an enclosure for the speakers to sit in (decoupled on Sorbothane or Neoprene) and then make a flush mount panel surface on the front of the traps. The flush mount panel will need to be as massive as possible. I recommend 2 layers of 3/4" (2cm plywood). The flush plane needs only be a little taller than it is wide.
Have a look at the Genelec docs...
Note: do not simply put them in the traps without the flush mount panel.
Cheers,
John

I know that the flushmounting seems to be the best solution but I would prefer to avoid it because of various reasons:

- I use 2 pairs of speakers. If I flushmount one pair it will probably affect the possibility of having the other pair.

- one of the pairs is Barefoots MM27 that can't be flushmounted (although I can replace those)
- If I decide to change the speakers later for some reason it's a very complicated process.

But maybe I'll have forget about all this...

Originally Posted by ritelec

Eduardo,

I believe it was your studio build I was following a couple years back........

Some place you got there !!! Very nice !!!
-rich

Originally Posted by DanDan

Seems like a shame to deconstruct and then do a major construct. There may be options.
Eduardo, are you fully sure that 100Hz dip is caused by the front wall?
How deep are those traps?
How deep and what density is the front layer of rigid fibre?
I suspect such a trap with mixed densities is probably not as efficient as a simple thick layer.
You could try that.
If there is not enough improvement, change the fronts to slats or perf. Tune it to your problem frequency.
Slats tend to look good.
DD

I don't think that the problem is only coming from the bouncing from the front wall, but I'm almost sure that if I get the monitors closer to the front wall the SBIR will reduce because I will have more ways to get the speakers to be in more different distances from the closer boundaries.

I'm sure that it isn't from the back wall.
I made this test and it had very little influence in the problem:

Rockwool panels packs placed on the back.



Left Monitor
Red Line - Before Rockwool packs
Green Line - After Rockwool packs




But when I moved the speaker in different heights and closer to the wall with the basstrap emptied the 100-130 dip started to have some change.

Here is the post where I got to this conclusion:
http://www.gearslutz.com/board/5245781-post596.html

This topic is getting too close to the SBIR thread, maybe I'll shift this posts to there and we can keep talking about where should you have the racks if you have too much gear for the room (like me )

[ritelec]

I feel your pain...........

$40., $400., $4,000., $40,000., or $400,000.......................into it.
The sound still wants to do the same thing. Amazing stuff!

[EduardoApolonia]

This is the original as it is today:




This is what I was thinking of:



Or this one that not being as functional I understand that it would be better acoustically, not only for the lack of back reflections but also for a better symmetry.



What are your opinions about it?