Small Portable Weatherproof Speaker

[smscad]

Hi all,

I want to make a portable weatherproof speaker. I plan to use the Tripath TA2020 Amplifier that will be powered by a 12V 7ah SLA battery. I have found these waterproof speakers that I was planning on using. The speaker needs to be weatherproof as I want to be able to mount it on a bike rack for our tandem bike, use it by the pool and while camping.

I would like some advice on whether these speakers are appropriate to use with this amplifier. Is 4 ohm better than 8ohm in this case? Do I need any tweeters?

I have come up with a rough housing shape. I want to be able to have the speaker be able to sit flat or in a vertical position. Is the housing large enough? Should I keep the battery compartment separate from the speaker housing? I have attached a drawing of what I am thinking.

Any help would be greatly appreciated.

Regards,

Simon

Amplifier
Tripath TA2020 PCB 25Watt Class-T Audio Amplifier Board | eBay

Battery specs
7.2 Amp Hour 12V Sealed Lead Acid Battery - Jaycar Electronics

Speakers
FR 13 WP Black - 4 Ohm

 

[mrduke]

Seems like those speakers are weatherproof on "both" sides, with fully encased magnet etc. it also is weatherproof on the back side. It might be overkill for you if you build the box well sealed, since there are a variety of regular speakers that are more or less weatherproof on the front and would give you a better bang for the buck.
For the TA2020 chip 4 Ohms gives more output but 8 Ohm slightly better efficiency for the amp. I think 4 Ohms are generally preferred for that amp/chip.
For a portable speaker I do recommend tweeters, since listeners are generally never on-axis. (Full-range speakers does generally not spread high freqs very good.) It is of course a matter of taste since tweeters increase the complexity, cost and so on.

 

[smscad]

Thanks for the reply Mr Duke.
The speaker information says "IP protection class for front side when built into a sealed enclosure" so I think it is only the front that is waterproof. I need to find a speaker available in Australia. There doesn't appear to be a great deal of variety that I can find. Do you have a suggestion for tweeter size or type?
How do I know how big the enclosure should be for this speaker. I want to make sure the enclosure size is suitable. Should both speakers be in the same space or do they need to be kept separate?

 

[Bare]

Earbuds! Skull Candy brand..if You can afford those

 

[katana2112]

How about boat speakers?
NEW Bazooka MAC6502B 2-Way 6.5" Marine Audio Speakers Black (Pair) | eBay
Just a thought.....

 

[smscad]

@Kantana
The speaker I originally specified is for a marine application.
@Bare
I want to include some other features besides the speakers ie charge phone while playing music, that earbuds can't do. It was worth suggesting though

 

[mrduke]

The speaker information says "IP protection class for front side when built into a sealed enclosure" so I think it is only the front that is waterproof.

OK, got it but my point was only that most regular speakers can take quite some "weather abuse" before actually breaking. Have you read the Boominator thread here on the forum? That design uses just treated paper cones and is used it some of the most gnarly, rainy rock festivals you will find... How weatherproof are you really looking at?

Do you have a suggestion for tweeter size or type?

Just make sure it has higher sensitivity than the woofers so you can attenuate it to the right level. You don't want to attenuate the woofer! And make sure it has wide dispersion, like not variants with deep waveguides or horns.

How do I know how big the enclosure should be for this speaker. I want to make sure the enclosure size is suitable. Should both speakers be in the same space or do they need to be kept separate?

Download winISD or similar modeling SW and put in the T/S parameters of the woofers. There are guides how to do this, just google it. I would say keep them in separate volumes...

 

[smscad]

Found another speaker. From my reading of the boominator thread it sounds like the higher the efficiency the better.
Would this be suitable for the Tripath amp. I wasn't sure if the rated power of 20W is to low to be used with the tripath amp.
R 10 S - 4 Ohm

 

[mrduke]

Found another speaker. From my reading of the boominator thread it sounds like the higher the efficiency the better.
Would this be suitable for the Tripath amp. I wasn't sure if the rated power of 20W is to low to be used with the tripath amp.
R 10 S - 4 Ohm

Yep efficiency is very important for how loud you can go with the limited power a battery based and portable system can provide you with.
The speaker you link to is probably pretty crappy, the freq chat show huge in-linearities in response and the FS is high (180Hz) meaning you will have no bass.
I don't have any experience of it, but a lot of people have reported good results with the SP-60/4 or SP-60/8 from Monacor. It needs a tweeter though.
I am just finalizing a portable speaker with the NS3 from aurasound. Please note that it is not very loud, that is not the purpose of that one: http://www.diyaudio.com/forums/class-d/221772-completed-micro-boombox-ta2020.html

I think you need to find a proper diy hifi store to start with, seems other Aussies solves it by shipping in from overseas:
http://www.diyaudio.com/forums/mult...here-buy-speakers-drivers-subs-australia.html

 

[smscad]

OK, I think I'm getting the hang of reading these charts now.

Would this be a better combination
http://www.essentialaudio.com.au/pdf/vifa/Vifa_TC9FD-18-08.pdf
http://www.essentialaudio.com.au/pdf/vifa/Vifa_BC25SC55-04.pdf

I don't think I'll worry about trying to waterproof.

If they are alright then I have a couple of questions.
Do they need separate enclosures or do the tweeter and driver go in the same enclosure?
How do I know what to use as the crossover?

 

[mrduke]

Just reading the specs and not simulating it, I think those drivers start to look ok. However, you might want to think about your design preferences before ordering and designing crossovers. For example, how big can the box be, and do you prefer ported ("more" bass but bigger box) or sealed ("less" bass but smaller enclosure without holes in) design.
How large is the internal volume of the box you was planning for?
Also, how loud do you want it to be? 86 db/1W is ok but not stunning.

The tweeter does not need a enclosure at all, but it is most convenient to mount it in the same one as the woofer. Mostly because you want somewhere to hide the cables, and positioning is tricky otherwise ;-)
No seriously, it goes in the same enclosure as the woofer.

 

[smscad]

I'm looking at about a 2.5L enclosure each side. I was thinking sealed but am open to suggestions. My overall design is about 150x150x300

Is 86 db/1W to low. Would I be wise to look for a higher sensitivity say around 90 db/1W. I've really got no idea how loud that is.

 

[mrduke]

I simulated the Vifa driver in winISD with 2 liter (per driver) sealed enclosure. Something like that should be ok. Qtc is close to 1, and F3 is about 122 Hz.

 

[mrduke]

Ah did not see your last message. 2.5 liters if good too. Gives slightly lower Qtc and F3 which is good. Those speakers works best in sealed design.
90 dB/1W would mean that the setup would be more than twice as loud.
With 86 dB/1W, 8 Ohm speakers and a TA2020 chip you would reach something like 98 dB at full blast, perhaps a little more.
I would say it is enough for normal to loud music listening, bbq etc, but not loud enough to have drunken all-out party. Maybe indoors...

 

[smscad]

Received the amp yesterday.

 

[sreten]

Hi,

The Vifa fullrange doesn't need an additional tweeter, use it on its own.

rgds, sreten.

 

[smscad]

Thanks sreten,

I'm thinking that just the driver without tweeters may be my best option as it is my first build.