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PostPosted: Mon Dec 12, 2011 1:47 am 
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Greetings all

This is my first post and I'm finding all the discussions here really civil and valuable. :D

I'm building a new purpose designed basement studio as I'm building the rest of my house as owner builder.

I cant work out how to do the flush mounts for my studio design. My acoustician has designed the monitors to lean in to the room. I see this on many photos of studios but I'm baffled as to how to make a reliable mount given there will be years of vibrations.

The design barefoot has here is the best I can find so far IF my speakers were standing perfectly upright. But according to my design, they're not. With just a strap holding them in they could fall out. But to provide some sort of architrave to hold them in would couple to the outer frame.

Does anyone have any suggestions? I definately want to have the option of changing the speakers in the future. Hence barefoots method holds. At the moment I will be mounting Duntech PCL25. These are a non ported design and I would also like to hear any arguments for OR against flush mounts at all in my situation.

Attached is my translation (for the carpenter) of John Brandt's custom design. The dashed line in front of the speakers is the point where the flush panel/frame meets the ceiling. Disregard the HVAC baffle boxes.

Cheers
Ben



Acoustician is John Brandt.


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PostPosted: Wed Dec 14, 2011 5:37 am 
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With just a strap holding them in they could fall out. But to provide some sort of architrave to hold them in would couple to the outer frame.
If the strap is tight enough then they wont fall out. Besides, the angle is only very slight: The tilt should only be a few degrees, and NEVER more than 10 degrees, so there's no reason why they would fall out on such a small angle.

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PostPosted: Wed Dec 14, 2011 11:39 am 
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Thanks for reply Stewart. My angle is 9 degrees :shock: There's not much info on this lean in. What I've managed to decifer is

1. that it has to start from 1200 and no higher
2. the centre of speaker perpendicular should pass over any lcd monitors or other equip at bridge.
3. I've pointed it for standing at listening position which also happens to be at ear level on the back client couch if they are sitting. When I listen to farfields I'm generally standing or walking around.

If I could start the lean in higher it would be easier to design and less precarious.

I was thinking I could put rubber on the shelf and even under the straps. Would this be a problem?

Cheers
Ben


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PostPosted: Wed Dec 14, 2011 4:09 pm 
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9 degrees is fine, Ben, as long as the rest of the room design takes that into account. When you angle your speakers down, it can cause issues that you need to be careful about. The higher the angle, the greater chance you have of getting reflections from yours console and/or desk surface, comb filtering, and psycho-acoustical issues from having the stereo image coming from too high above the horizon: it messes with your brain's ability to determine direction accurately, and also can mess with your ears' ability to hear flat response. The sweet spot also takes on an incline, instead of being flat. etc. Lots of issues. A really top designer knows high to deal with those, and might risk going a bit more than 10°, but for us mortals 10 is pretty much the limit.

I'm surprised John didn't detail the method he had planned for mounting the speakers: that would normally be part of the service he provides. You might want to ask him about that, since he designed it!

Quote:
1. that it has to start from 1200 and no higher
1.2 meters (1200 mm) is the recommend height for the acoustic center of speakers when they are NOT tilted, for a simple reason: that is roughly the average height of your ears above the floor when seated, for most people. So normally you have the acoustic axis of your speaker at 1.2m, no tilt, and then it is aimed right at your ears. If you tilt the speaker down, then you pretty much have to get it above 1.2m, so I'm not sure how John was dealing with that. You should ask him.

Not sure why John would recommend that as the maximum height for the speaker when tilted. Maybe he was talking about the base of the speaker, not the acoustic axis? Perhaps something to do with size of your speakers, then 9° angle, the distance to your ears... or some such. There isn't enough info on that plan you posted to figure it out.

Quote:
2. the centre of speaker perpendicular should pass over any lcd monitors or other equip at bridge.
Yup. You don't want any physical object getting in between your ears and the speakers. You need a clean, direct path from speaker to ear, so it is important to keep the acoustic axis above obstructions.

Quote:
3. I've pointed it for standing at listening position which also happens to be at ear level on the back client couch if they are sitting. When I listen to farfields I'm generally standing or walking around.
You don't mix sitting down? :shock: That's unusual, but if that's how you work then that's what it should be. Personally, my legs and back would give out after a few hours trying to mix like that. I guess you also have your desk built a lot taller than normal? Also, if you are moving around the room, then you are not in the sweet spot so yo won't be hearing the sound stage accurately. Did you explain your unusual requirements to John when you hired him to do your design? There's a pretty much "standard" way of laying out speaker and mix position geometry, so if he wasn't aware that you normally stand, then he might not have designed that they way you need.

Quote:
If I could start the lean in higher it would be easier to design and less precarious.
There might be good acoustic reasons why John did not want the speakers set higher, such as putting them in potential null points for certain room modes. Ask him about that: you might be able to go higher, but if you do then you'd have to tilt more, and that would not be a good idea. 10° is about as much as you ever want to tilt, unless you take fully understand the issues and take extreme precautions to deal with them. Not for the feint of heart!

Quote:
I was thinking I could put rubber on the shelf and even under the straps. Would this be a problem?
That would be fine! I seem to recall a photo here on the forum somewhere of a setup that someone did just like that. You need the rubber underneath in any case, to decouple, and putting rubber under the straps would help with that too, while also protecting the speaker finish from the straps, and giving you a more secure mounting.


But overall I'd suggest that you contact John Brandt again, and ask him about all these details. If he did the design, then he knows what he had in mind, and since you paid for his services, I'm sure he wouldn't mind clarifying the speaker mount issue.


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PostPosted: Wed Dec 14, 2011 5:17 pm 
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It seems to me Barefoots mounting techniques involve the speaker being mounted on a completely isolated structure. He shows clamping with straps but this could also be a more rigid i.e. wooden clamp mount. There would be mechanical conduction to the mount however unlike John Sayers' mounting, Barefoot's as mentioned, is not coupled to the baffle so there should be no problem.

I don't think bcslaam mixes standing up Stuart. This is just listening at altered perspectives it helps in determining the translation, simply a precursor to listening in other environments. This has the advantage of being able to go back to the desk and tweak the mix. Chances are he'll have a set of nearfield reference monitors at the desk. Bcslaam, please correct me if I'm wrong on this.

The stipulation of a minimum of 1200 is possibly in reference to the overall dimensions of the baffle which has no doubt been calculated for optimum performance. Acoustic reasons - as you said Stuart. We have to keep in mind too that these are not designed for the near field unlike many of the designs here to which we are accustomed. The flush mounts I will be installing in my own room are also meant for "far" field (perhaps "far" is pushing it considering it's a small room :wink: ).

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PostPosted: Wed Dec 14, 2011 5:39 pm 
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We have to keep in mind too that these are not designed for the near field unlike many of the designs here to which we are accustomed. The flush mounts I will be installing in my own room are also meant for "far" field (perhaps "far" is pushing it considering it's a small room
Yup! Very true. For most studios here, there really isn't any such thing as a "far" field at all! You simply cannot get further away from the speaker than the critical distance, so all speakers in home studios (and even small "pro" studios) are really "near-fields", to be strictly accurate.


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PostPosted: Wed Dec 14, 2011 6:22 pm 
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Near field to me is any configuration of speakers where the distance LP to speaker is less than 2 meters, and I'd say 2 meters is even pushing it. Much more than this and the room (aside from the usual 1st reflection points which must be handled even for the nearfield configuration) begins to have more impact on the sound thereby diminishing the advantages of nearfield monitoring.

I'll compromise with you and say "mid-field", or we could just use the term "Bigs" :lol:

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PostPosted: Thu Dec 15, 2011 2:16 am 
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Actually, it all depends on what type of "near field" you are talking about! There are two types, and two definitions. If you are just talking about naked speakers in open air (no room) then there are equations for calculating what "near field" and "far field" mean for that speaker, based on the dimensions. But basically the transition from near to far occurs at roughly 7 times the largest dimension of the speaker face. So a 12 inch tall speaker will transition roughly 7 feet from the speaker face. That is purely a speaker-related issue, and has nothing to do with the room.

But there is also "near field" and "far field" for the room itself, independent of the speaker and that too can be calculated and measured. It occurs at the point where the sound field transitions from direct to reverberant, or from 6db to 3dB change per distance doubling. That is referred to as the "critical distance" for the room, and is not related to the speaker itself: any speaker will give the same result, since it it totally a room issue, based on volume, absorption, etc.

So the question is, what happens to the near-field / far-field of the speaker, when you put it in a room with its own near-field and far field? That's the million dollar question that nobody knows how to answer. But basically, the room wins. Regardless of the speaker, the room has its own near and far field. And in a small room, by definition there is no far field, since it is frequency dependent! You simply cannot have a statistical reverberant field in a small room, because the wavelengths do not fit. That's why RT-60 measurements for small rooms really are not RT-60 measurements at all! They are more accurately just modal response measurements. In order to have a fully reverberant field, you need a room where the dimensions are at least 7 times the shortest wavelength that you want to be reverberant. Do the math: that's a very large room at 20 Hz.!!! :shock: That's why you'll see folks say that small rooms have no reverberant field, and no RT-60. So they also have no far field.

In other words, the terms "near field" and "far field" as applied to speakers are pretty meaningless, since it is the room that determines the actual response, and there simply is no such things as a "far field" in the vast majority of home studios.

And of course "mid field" is pure marketing hype: Technically, there is no such thing.

There was a great discussion about this point over at Studio Tips a few years back, with guys like Eric Desart, Rod Gervais, Bob Golds and Bert Stoltenburg. I have a link to that somewere, but I couldn't find it.... Anyway, as I recall their basic conclusion was that nobody really knows what a "near field" or "far field" speaker is! There's no definition, so anyone can build a speaker and call it whatever they want. Those names are much more marketing-oriented than actual technically valid specifications, especially considering that it is the room itself that has the last word, and no home studio actually has anything even remotely resembling a far field anyway.


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PostPosted: Thu Dec 15, 2011 2:23 am 
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Soundman2020 your right about the lean-in being dangerous teritory. It was doing my head in. I did start to get close. For prosperities sake attached are the rough drawings.

But after a phone call with John today we agreed it would complicate things to much for my application. I will keep it vertical and fix the speaker shelf in the outer frame and use neoprene/rubber or similar to decouple on the bottom and around the straps (any product hints?). I'll go the way of a cantilevered shelf, or extend 2 legs down to the floor, either way fixing to the outer frame.

John does do it for bigger studios but I have a medium to small room. My Duntech PCL25 were originally made to face almost straight out, 3.6m apart! However as BriHar pointed out I have other "nearfields" (JBL4328P) that will be on decent solid stands behind console. The duntechs are great for filling in the gaps and another perspective, they have a lot better mid range than the JBLs. I think they will be extremely useful as flushmounts.

John pointed out that centre axis of speaker should be at sitting ear level and that the apex of the 60 degree lines be 150mm behind the head. I then pointed out it needed to clear a big pair of 33" lcd monitors. We decided on an axis line that clears the top of the screen. For me, so I can have good posture, that would mean my speaker shelf would be at 1300mm and thus axis at 1600mm which suites for standing at LP and client couch. I'm happy.


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PostPosted: Mon Jan 23, 2012 9:15 pm 
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Yeah, great and fantastic article sir, we've got guidelines from this like you've said that if we're in France there could be a lots of ways to learn and to do things, very nice article and thanks for sharing your valuable thoughts with us. // it is agood post made by you thanks for sharing it here i like it so much.. :yahoo:


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