@scattershot
I think we got our wires crossed a little bit!
I was suggesting the Sierra Tower
Center , not the Sierra Towers. Confusing names, obviously
Ascend doesn't have the Sierra Tower
Center on their main website yet. Dave is still tinkering with possible alternative cabinet designs, so he's basically keeping this particular speaker a little bit under wraps until everything is finalized and he can really ramp up production. There's enough word of mouth on the Sierra Tower Center already to keep Ascend plenty busy with made-to-order purchases!
You can read a little bit about the dimensions and see some pics of the cabinets in
this thread at the Ascend Forum . You'll have to create an account for the forum if you don't already have one in order to view the pics
And you can read the huge long thread where the Sierra Tower Center picks up the name "Horizon" in
this thread here .
So a little explanation is in order. First up, Dave decided he didn't really want the final name to be "Sierra Tower Center". Hence the name "Horizon" has been adopted. The reason he didn't want to end up with the final name being "Center" is detailed in his first post in the main thread about this particular speaker (2nd link above).
The Horizon isn't just a center speaker. It also makes great Main Left & Right speakers! All while being positioned horizontally!
It is 11" tall, so it will easily fit your 20" maximum height clearance. It's nearly 2 feet wide, but that's ok. You said you have an 8 foot shelf, so you'll still have some room between the three speakers up there. And it is front ported, which is definitely a plus in your type of installation! You wouldn't want to deal with a rear port. So sealed or front ported speakers are definitely the way to go in your case!
Once again, the link to purchase the Sierra Tower Center/Horizon is
live and available here . Take note that the price is for ONE speaker at a time. Not a pair
Now, I mentioned the RAAL ribbon tweeter upgrade, but that was before I knew about this 6.25 foot elevated shelf situation! That changes things!
The one thing the ribbon tweeter lacks is tall vertical dispersion. You pretty much need to have your ears within the boundaries of the ribbon tweeter - and the tweeter isn't very big! So you really need to have the tweeter right at ear level for the very best sound with the RAAL.
What would make WAY more sense in your setup would be to stick with the regular NrT tweeter, which is still excellent! It has much taller vertical dispersion than the RAAL, and it will be much less of a problem with your setup.
You will still want to angle your speakers downwards to aim them at the seats. But the NrT tweeter will handle this less than ideal placement much better. As an added bonus, that brings the price for a pair down by $700! So they're well and truly within your price range now! And you could even afford one of the nicer finish options
I'm a big, big fan of either the "Natural" bamboo or the "Dark Cherry", myself
When you have a clearly compromised placement like yours, there's such a thing as sending good money after bad. You're not going to fix your less than ideal placement with higher quality speakers. You're just going to bring down the performance of the speakers with the poor placement, I'm afraid
It doesn't make sense to be looking at $2500/pair bookshelf speakers that are just going to be crippled by where they're placed. It makes MUCH more sense to spend less money on speakers that will better handle the poor placement.
I'd use
Auralex MoPads to decouple the speakers from that high shelf, for sure. The MoPads can also angle the speakers downwards by as much as 8 degrees. I think you might need even more tilt than that, so you could use your rubber doorstops as well to get the angle just right. The MoPads have a nice little "lip" on the front that will help to hold the front of the speakers from slipping forward on the downward slope
I would also probably turn the speakers upside down. This will get the tweeter as low as possible and thus as close to ear level as possible. But it will also put the front slot ports of the Ascend Horizon speakers on the top, which will prevent them from firing down into the shelf with the fairly steep downward angle.
If you ever find a way to have better placement, the Ascend Sierra Tower Center/Horizon speakers will still reward you with stellar sound quality. And if you're dead set on having 5 identical speakers, the horizontal form factor and front ports will make them easier to use in the surround positions as well.
So I still have the Horizon as my top recommendation for you. It's an excellent, excellent speaker. And though it was designed as a dedicated Center initially, it's proven its chops as a Main Left & Right speaker. Enough that Dave wanted to change the name from Sierra Tower Center to Sierra Horizon
So I hope that clears up the confusion! These aren't the Sierra Tower speakers. These are the 11 inch tall, 23 inch wide, front ported "Sierra Tower Center". And I'm recommending you get three of them to put on that shelf above your TV. And I'm recommending you stick with the NrT tweeter. As much as I love the RAAL ribbon upgrade, the placement demands better vertical dispersion than the RAAL offers. And sticking with the NrT makes the price fall right in line with where you want it to be. So it's a win-win
Hope that helps!