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Portable Battery 2 way speaker

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Jack1991 View Drop Down
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    Posted: 16 March 2022 at 8:42pm
Planning on making a portable speaker. Bought a few bits for it already but thought id make a build thread and hopefully get opinions on it to make sure im going the right way about it. Doing it as a bit of a experiment and a learning curve and just a bit of fun really. Hoping it to weigh under 15kg in total.

What im using:
P-Audio 410 Tweeter, spl 105db
8" Fane Sovereign 8-225, spl 97db
2.5k convair crossover (making use of one i already have)
NE5532 Preamp
TPA3255 amplifier board (using just 1 channel to get around 80w at 35v 8Ω)
18v Makita Battery
Dc step up converter (to step up the 18v to around 35v)
12mm Baltic Birch Plywood

As im only using 1 channel on the amplifier circuit board i will have to make the input mono. I will only ever use my phone with it so ill just set my phone setting to combine channels to mono.

Been on winisd for ages trying different drivers to try and find the 'best' for what i am after. Im still a n00b on here so a bit of assuming took place. So be good to get confirmation that im right according to the graphs. I tried a few drivers to get it as low as possible and the fane turnt up best. Also at 97db spl it seemed the best bang for buck especially as its on a 12v system.

Box exterior size at the moment is roughly 45cm high X 27cm wide X 37cm deep. The woofer chamber is 23378cm³. And then after speaker/port displacement it works out to 21 litres tuned to 57hz. I had to go slot port to keep air velocity to a minimum. From what i have read under 20m/s is best to avoid chuffing?  I planned on using a 2" round port at first but then after checking cone excurision it was sky high! Up in the 60/70 m/s. And using a bigger round port it had to be far too long. So slot port works out perfectly... I hope anyway.

I am kind of plucking the box tuning hz out of thin air to be honest. I cant imagine what different hz would sound like as i dont play any instruments or anything. So i have just aimed to get it as low as possible. I know the lower it plays the bigger the box so its a bit of a trade off. And this seemed like the biggest i would like the box to be. But will it be low enough? I play reggae/dub/dnb/jungle and just general dance electronic tunes.












Edited by Jack1991 - 10 April 2022 at 7:43pm
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Jack1991 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2022 at 7:30pm
Made it today. Heres a couple pics during glueing & screwing





The empty compartment behind where the tweeter will be is to house the battery, crossover, amplifier and the dc step up. Needed it big enough to get my hands in to screw the parts in place, seems just about right. Will find out soon if it is or not. Also it will have a little door on it which will be fitted later.


Edited by Jack1991 - 20 March 2022 at 7:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 26 March 2022 at 3:44pm
All built and tested, not fully finished, just a test with external amplifier but it sounds good! One thing i wish i done was put the port on the front. As from behind the bass sounds pretty pumping for the size of it, i was impressed. But the front not so much, until i turn it right up then can hear it more.





Would it work the same on the front as i have the 15mm overhang lip on the front. I was thinking if i had the port at the bottom under the 8".  But because it has the 15mm extra length at the bottom of the port, would that affect it? The top of the port would finish in line with the face. Hope that makes sense to you?



If it will work i will remake it all with a front port. I enjoyed making it and the wood is free off a mate anyway so its all good.


Edited by Jack1991 - 26 March 2022 at 3:47pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2022 at 11:57am
*V2 ready for testing*

Hopefully having the port on the front makes it sound better. Definitely looks better i think! (obviously the cable wont be like that when its finished proper)




Edited by Jack1991 - 09 April 2022 at 11:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2022 at 12:58pm
Nice work! I'm interested to hear your opinion on the port location difference in free space. Imho, a box folded grille would look nicer than the round one. Maybe just leaving the port open.  What are you considering as a finish?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2022 at 2:21pm
Originally posted by Lucasdude Lucasdude wrote:

Nice work! I'm interested to hear your opinion on the port location difference in free space. Imho, a box folded grille would look nicer than the round one. Maybe just leaving the port open.  What are you considering as a finish?

Cheers man!
 

Ah yeh a box folded grille would look quite cool actually.

Its more of just a fun little experiment at the moment though. But i might consider changing it in future. Im not sure the lip would be thick enough to cater for a box grille, its a 15mm lip. How do they fix them in too?

Yeh i cant wait to hear it too. I will test it out tommorow or monday as im out for the day now. It 




Edited by Jack1991 - 09 April 2022 at 2:21pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2022 at 2:39pm
For that baffle size, I would just look for 4x15mm rubber spacers and use wood screws with small washers, but check the woofer excusion clearance first! The guy at speakergrilles can box fold grilles to your custom size.


Edited by Lucasdude - 09 April 2022 at 2:43pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2022 at 6:54pm
Cool cheers. Been thinking about it today and going to stick with what i got now. But good to know for future projects.

Also tested it in the garden earlier today and it sounds loads better with the port on the front! Need to take it out somewhere though to proper test it turning up the volume. Didnt want to play it loud in the garden.

Another thing ive changed from the start is im going to run it off of a 18v Makita Battery. And also i am going to probably need to use a preamp too.



Edited by Jack1991 - 10 April 2022 at 7:42pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2022 at 8:55pm
If you're using a phone or similar as a music source, try the "Poweramp" app. The SQ and file support is great, it's an easy way to sum to mono, and you can also use the EQ as a high pass filter so you're not robbing the battery power with inaudible frequencies. When I'm using a battery system, I also have a little Sony laser projector than can display the visualization from the app, if you're ever in that sort of mood...


Edited by Lucasdude - 10 April 2022 at 8:58pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2022 at 9:31pm
Cool cheers just downloaded it now its really good! Thats a good idea too with to use it as a filter to save wasting battery.

I cant find how to sum to mono on there though?

Also sorry only just realised i didnt answer your question about what im using for finish. Osmo Oil, ts my favourite wood finish really brings out the grain, with barely no shine, nice natural look.


Edited by Jack1991 - 10 April 2022 at 9:56pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2022 at 10:26pm
In Poweramp, under EQ click the middle knob looking icon at the top middle. You'll find mono setting there. You can also boost the output with "Preamp" in the EQ.
   I like the sound of just oiling a well sanded finish. Maybe 4 stout rubber feet will protect the bottom from grass damp.
  Looking at the specs for that power amp, the maximum input voltage is 40v, so you could also consider using 2x 18v batteries in series and lose the step up converter. I'm not sure which batteries you have, but I remember the red ni-cad ones being crap. Those slim black Li ones are half the weight and much better.


Edited by Lucasdude - 10 April 2022 at 11:09pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jack1991 Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2022 at 8:52am
Cool yeh the preamp bit looks good too.

Yeh ive been thinkiing maybe 4 black rubber feet might look good. Also nice to raise it off ground.

I was thinking that too but someone over on another 12v forum said not to push those amps too hard  and said around 30v would be max. As he blew a few at 36v.

I did try finding better amps but all i can really find is chinese ones like that TPA3255 etc.

Yeh i have the black 18v li-ion batteries 5AH so should be all good hopefully.


Edited by Jack1991 - 11 April 2022 at 9:53am
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