Era 100 or 300 and speaker placement

You are trying to compare apples and oranges, they are intrinsically different and picking one is a matter of taste, not comparison.

The 100 doesn't need much side room... because it has no side drivers. Of course with no side drivers there is no side channel sound.

The 300 has side channel drivers and they need room to work properly, the minimum distance is a minimum, not optimum distance.

Same for the height channel, it needs to bounce sound off the ceiling for optimal sound. Since your image didn't post I can't see how that would work out.

Now as to picking, go with the 300s if at all possible, even in less than optimal positions they are going to add more Atmos impact than the 100s.

In my case I bought both and tried them, couldn't position the 300s to suite the spouse so I used the 100s instead. I'm quite happy with the 100s as surrounds, they are noticeably different than the 300s but better than no surrounds that was the other option here. The 300s make a wonderful stereo/Atmos pair in another room, where the 100s would have gone if not used as surrounds.

Appreciate the feedback. Not sure why the image is not loading as it is showing up for me, but not a big deal. 

Out of curiousity (as I also have a spouse to please) were the 300s too loud or overpowering for you wife? or did she just prefer the 100s over the 300s?

How can they be “too loud”? Just reduce the volume, surely? 
 

It was aesthetics (over speaker placement) that I had to cope with rather than anything else, to get spousal approval for my wall-mounted 300’s. 

Purely placement, the 300s needed to be in one of several places to work well and none met with approval. Some mine, the remaining spots hers. The 100s just went in where we had Play 1s for our old Arc, better sound than the Play 1s so it was some Improvement. 

No sound issues from the 300s when placed in line with the Sonos suggested mininimums or better.

The image is showing now, likely just forum slowness.

My only concern is that the window sill isn’t high enough above the rear of the couch. However I can’t discern that from the diagram. 

The Era 300’s really need as much clearance as possible before the audio output encounters a blockage which concerns me regarding the rear of the couch.  However, as has been said they are the better choice for the Arc Ultra to create the Dolby Atmos surround bubble.

If possible I would consider moving the couch forward and mounting the Era 300’s on stands directly behind the Arm Rests of the couch. Assuming the diagram is a close representation of the furnishings.

The alternative choice is to mount them on the rear wall above the couch possibly centered above each window or to either side. 

Loudness is subjective. Mine are mount on stands on either side of my eight (8) foot double theater seating. Surround sound is typically lower than the ArcUltra and balanced. You can always adjust the audio or allow TruePlay to set the audio level.
 

If above the windows is an option, consider possibly mounting them inverted and close to the ceiling. 

I apologize, did not do a good job describing the window sil. T

The window sil is about 12” deep (just measured it) and the window itself is recessed into the wall, so all around the window is about 12” which I could set the era 300s on the window sil and basically use it as a shelf.

Since the window is recessed I didnt know if this would be too enclosed around the speaker.
I cannot mount them above the windows, however I can mount them to the side of each window. 

Appreciate all the feedback!

Thanks for the reply. However, the concern (or mine) is whether or not the Window sill is above, slightly below or even with the highest point of the back of the couch/sofa. 

The window sil is slightly above the back of the couch right at ear level and they go about 3.5’ up the wall. Its right at ear level maybe 3’ to 3.5’ off the floor.

Thanks again for the reply. If mounting the Era 300’s on the window sill is your best and only option then so be it.

However, proper placement suggests that surrounds be placed 6 to inches to the outside and 12 inches to the rear on either side of the sofa/couch. In all honesty that is an ideal placement that even I can’t fully adhere to.

In your case I’d consider moving the sofa/couch forward and using stands to approximate the ideal placement as mentioned. The other alternative is to wall mount them as far out to the left and right as possible inline with the ends of the sofa/couch.

If the window sill is still your best option then position them to the furthest corner of the will sill away from the centers with the suggested clearance on either side. 

Here is a photo to make more sense of it.

That picture really leans me towards inverted above the windows, what is the reason you aren't considering that?

Three feet in from the side walls should be excellent given my experiments with my 300 Pair. Or go for centered on the windows to balance the appearance.

The windows are tall enough they should be OK for height but look pretty narrow to get the side clearance you're going to want.

 IMO you could wall mount  the speakers if you can find a stud or above the windows if there is header behind the wall board. 

If your dwelling is an apartment I understand the reluctance to drill holes. That being the case I would seriously think about moving the sofa forward enough to force stands in place to mount the speakers using the same line as shown for wall mounting. Actually, as I look closer the speaker on the left would easily fit on a stand behind the table with the lamp.

Unfortunately IMO placing the speakers in the window sills would place then directly behind someone’s head….not good 😕

The above is all the advice I can offer. Hopefully you’ll figure out what works best for you 😊

The stud location issue can be solved with what is called a "fan mounting box" that goes in through a small hole and then expands to secure to the adjoining studs. Many are rated to hold a 50 pound fan so speakers are not an issue.