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!
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.
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.
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?
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.
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!
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.
- Stuart -
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