Back box for 8 inch Atmos Speakers

[Apichai]

Hi,
I've read many recommendation to add back box to ceiling atmos speakers. So, I'm looking for back box for 8" (Probably Polk V80) but none available locally. I have about a feet left above the ceiling so I'm thinking to make DIY back boxes for the speakers. Should a 1 ft x 1 ft x 10 inch box do it? I probably use plywood or 1/2 inch MDF.

Please suggest.
AP

 

[TLS Guy]

Hi,
I've read many recommendation to add back box to ceiling atmos speakers. So, I'm looking for back box for 8" (Probably Polk V80) but none available locally. I have about a feet left above the ceiling so I'm thinking to make DIY back boxes for the speakers. Should a 1 ft x 1 ft x 10 inch box do it? I probably use plywood or 1/2 inch MDF.

Please suggest.
AP

A back box is a good idea. However it is a loading that has to be optimal. So, there is an optimal back box for every speaker, whose volume needs to be calculated from the Thiel/Small parameters of the driver. The manufacturer should be able to provide that data, if the specs are not in the spec. sheet. If the T/S parameters are known, then I can calculate your optimal box.

I note those speakers are very expensive, and no T/S parameters seem to be available, and the Polk list them as out of stock.

I used Mark Audio full range drivers for my ceiling speakers. I think they are the best speakers for that application. Really good full range drivers without crossover are absolutely ideal for that application. They are sensitive and have lots of power in reserve and never disappoint. Their optimal back box is only 0.25 cu.ft. So they are easy to mount in the ceiling. I have been telling members for years these are the best drivers by far, for ceiling Atmos speakers. They could not be more ideal, and they will save you a lot of money. They are available from Madisound.

When the grill is on, they leave a nice finished flush appearance. You can see one of the four, the front left in the picture below. I have driven these speakers hard for three years now, without issue. They are driven from two 100 watt per channel amps, for the four. So 400 watts total.

My view is the design of almost all speakers sold as ceiling speakers is stupid and just wrong. You can do much better. I know and have.

 

[Apichai]

Thanks. Indeed, Polk does not provide the parameters you mentioned. I choose them because they have aimmable tweeter. There's not many choices here in Thailand.
Since we do not have much data on the drivers. I've just need typical "ball park" back box for those typical 8 inch ceiling speakers. Other speakers available locally are Wharfedale wcm-80, which are more expensive.

 

[TLS Guy]

Thanks. Indeed, Polk does not provide the parameters you mentioned. I choose them because they have aimmable tweeter. There's not many choices here in Thailand.
Since we do not have much data on the drivers. I've just need typical "ball park" back box for those typical 8 inch ceiling speakers. Other speakers available locally are Wharfedale wcm-80, which are more expensive.

There is no such thing as a typical back box. Any guess is right out of the back of the neck. Woofer testers are not that expensive, so you could measure the T/S parameters yourself. A too big or too small box will cause a very lumpy and likely boomy response. If it comes to that you would be better off with no box.