Where does phone DA come in? aptx and a2dp as modern bluetooth products have makes sure your music is moved bit for bit to the BT receiver if they're in a compatible format (usually MP3 and AAC). Naturally it requires that both transmitter and receiver are capable of aptx and a2dp.
And depending on the BT receiver you can have I2S output (or other digital formats, the bluecore5 chip support PCM/SPDIF/I2S digital outputs) directly.
I see a pretty big big list of things (SSD, big lithium battery, single board computer, DAC, speakers, enclosure...) and you really think you're going to beat the price of this thing?
That thing is not the same thing. It's just a BT speaker.
The cost is the same as a Boominator, minus BT, plus Pi ($40), dac ($40), SSD ($80). Amps would be cheap, the speakers won't if you want good sound, maybe $100 in components? Battery control circuits $10? Battery $40 to $100. I was thinking of using one of those lightweight LiFeO2 bike batteries. I'm not counting the enclosure, which I'll build from scratch. So perhaps $300 worth of material.
The components pose no issue, with the exception of I2S where some of the challenge might be, otherwise, the rest is straightforward. What you get is a hires media player that sounds good and doesn't need anything else.
It will have an ethernet port in the back to connect to the network for downloading new songs and a AC jack for charging the battery. Nothing else.
The cost is the same as a Boominator, minus BT, plus Pi ($40), dac ($40), SSD ($80). Amps would be cheap, the speakers won't if you want good sound, maybe $100 in components? Battery control circuits $10? Battery $40 to $100. I was thinking of using one of those lightweight LiFeO2 bike batteries. I'm not counting the enclosure, which I'll build from scratch. So perhaps $300 worth of material.
The components pose no issue, with the exception of I2S where some of the challenge might be, otherwise, the rest is straightforward. What you get is a hires media player that sounds good and doesn't need anything else.
It will have an ethernet port in the back to connect to the network for downloading new songs and a AC jack for charging the battery. Nothing else.
A Boominator is just a DIY active speaker design. There's no BT in the design but many add it. You can stuff every conceivable thing you need into it provided you make the room for it in the electronics compartment and expanding it as necessary. There are people that have built AirPlay capable versions with a rasberry pi b+ and external DAC just as yours so the jump to a mdp is very minor.
Yet you are proposing a portable, battery powered, Class D amplifier driven .... er .... "boombox" 😉
Difference in details, but not basic concept.
Just sayin'
And B&O already made it.
But you are free to make your own version, take the Market by storm, and make Millions, what's stopping you?
In fact, having conceived such a bright idea , what are you doing here? 😉
When I look at that B&O speaker I see multiple injection molds with lots of sliders to make the case, purpose-made flat speakers that fit the thin form factor, and tons of industry compliance testing/approvals required that extend from bluetooth spectrum testing to the CE mark on the wall wart charger that comes with the thing... and a pile of other engineering and NRE that has to be paid off.
And I'm pretty sure the folks at B&O consider the fact that they're not going to sell anywhere near as many of these as the cheap $50 bluetooth audio logs that Best Buy sells.
I'd hold off on calling it overpriced.
And I'm pretty sure the folks at B&O consider the fact that they're not going to sell anywhere near as many of these as the cheap $50 bluetooth audio logs that Best Buy sells.
I'd hold off on calling it overpriced.
Well you can get a portable BT speaker for not much money, so the $500 price of the B&O is (one hopes) for the sound quality. But then you are limited by the format of the audio files on your phone.
If sound quality is what you're paying for, then hires audio files fed to a decent DAC will sound better. If the $500 can buy you a standalone hires player, is there argument here that it would be inferior to the B&O? If it can be cheaper so much the better.
I was hoping that by now we might be discussing the merits of various components instead of the justification of the project. If you think it's a bad idea, just move on.
If sound quality is what you're paying for, then hires audio files fed to a decent DAC will sound better. If the $500 can buy you a standalone hires player, is there argument here that it would be inferior to the B&O? If it can be cheaper so much the better.
I was hoping that by now we might be discussing the merits of various components instead of the justification of the project. If you think it's a bad idea, just move on.
Starting from the speakers, focal makes some excellent shallow volume drivers. I can get the P 165 for a good price, they are fairly efficient too, easily driven by 20w. Another candidate might be this one:
http://www.tnt-audio.com/casse/t-speakers_e.html
I love audio nirvana drivers, and they are reasonable compared to what you get. The volume would have to be dampened since they like larger enclosures. The size is ideal and no crossover is needed.
http://www.tnt-audio.com/casse/t-speakers_e.html
I love audio nirvana drivers, and they are reasonable compared to what you get. The volume would have to be dampened since they like larger enclosures. The size is ideal and no crossover is needed.
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A way around the small enclosure issue might be mounting the drivers back to back and reverse the polarity on one. You'll get a bit cross talk between them, mostly in the bass where more air is moved.
Maybe, but that would make the cabinet twice as thick, so it would end up being more of a cuboid.
No problem in a desktop device but probably not as attractive or practical to carry as a portable music maker.
No problem in a desktop device but probably not as attractive or practical to carry as a portable music maker.
Yes, perhaps just a single audio nirvana with an extra rear facing tweeter. It would be a challenge to use such a large driver. A more practical solution might be one of the 4 in full range Tang Bands, ie. W4-1320SJ.
http://www.parts-express.com/tang-band-w4-1320sj-4-bamboo-cone-driver--264-847
http://www.parts-express.com/tang-band-w4-1320sj-4-bamboo-cone-driver--264-847
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http://www.commonsenseaudio.com/an3cfspecs.jpg
I think these are going to be the drivers for this project. At $88 per pair they are well within the budget and I've never been disappointed with the AN drivers.
For an amp, I was thinking of this one:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=121294927725
I think these are going to be the drivers for this project. At $88 per pair they are well within the budget and I've never been disappointed with the AN drivers.
For an amp, I was thinking of this one:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=121294927725
Not to be mean, but I think you have no idea what you're looking for.
You'll have no bass with those speakers and your battery life will be very low with that amp. The MPD is cool and all, but let's not lose the real goal: good sound.
Is beating the B&O still the goal?
You'll have no bass with those speakers and your battery life will be very low with that amp. The MPD is cool and all, but let's not lose the real goal: good sound.
Is beating the B&O still the goal?
We'll see.. The ANs go down to 140 Hz, so I am hoping with some cabinet tweaks to get there. I have built a pair of small speakers with the Tang Bands and the bass was ok. BTW, the enclosure doesn't have to be that small. Just portable.
You are right as far as battery life of course. 3 to 4 hours would be adequate for me. I liked that amp (but not the chip) for its tweakability. A TPA3130 would be much better than 3116. Harder to find.
I have started construction. I'm going to see if a TDA2003 is sufficient to power my drivers.
I do have a question: the final product will be mono. I was thinking it would be interesting to use the left and right channels of the amp to drive each driver and implement a digital crossover on the PI end. Does anyone know of this existing already? A jackd module perhaps outside of mpd?
I do have a question: the final product will be mono. I was thinking it would be interesting to use the left and right channels of the amp to drive each driver and implement a digital crossover on the PI end. Does anyone know of this existing already? A jackd module perhaps outside of mpd?
What sort of foot print are you aiming for? I'm interested in doing something similar to what you're doing. But as many people keep saying it's hard to achieve without tons of engineering (and the result is often mediocre compared to boominator etc) because of the small foot print of these commerical solutions.
Ideally I'd like to do something in the Bose Soundlink size.
I'll be following your progress, could you please link the parts you're using?
Thanks!
Ideally I'd like to do something in the Bose Soundlink size.
I'll be following your progress, could you please link the parts you're using?
Thanks!
My first try will not be the last. In the first iteration I'll be building something larger and once I figure everything out I'll work on shrinking it.
This is what I'm going to build for the first iteration, and I'm not saying I know all the answers (it's an experiment):
1. It will be a Mono system.
2. Speaker drivers, I'm just going to use some that I already have. Will change. Same with cabinet.
3. mpd system: Beaglebone black. I2S card (will see if I can get this working).
4. Amp: TDA 2003 based. 10W/channel - remember, mono build so will be almost like double.
5. Battery: Honda Grom WPS FeatherWeight 12v 8 Cell LiFePO4 Lithium Ion Battery (has LED for power remaining).
6. Charger: PCB Charger for 4 Packs 12V LiFePO4 Battery Cell at 5 7A Limited with Protection | eBay
I'm still researching digital crossover in the BBB. I think I have what I need.
I am done building this. Here is a picture of the components:
In the middle are the charging and protection circuit for the battery and the wifi. Clockwise from the battery:
+ Lithium battery
+ Beagle Black and the DAC board
+ Amp board
+ Power supply (that is removable and in a separate enclosure.
Here are the KEF drivers I ended up using:
Everything is made from planks recovered at the beach 🙂
Here's the detail of the handle:
Detail of the driver guard:
The side view:
And how does it sound? I am impressed. I get about 6 hours of playing time before it starts to stutter and then I plug it in and in 15 minutes it's charged again 🙂. Quite pleased really. It is about 13 inches high and as you can imagine, most of the weight is in the cabinet. I chose only old cedar so it's not heavy at all.
Best of all, listening right now to Kenny Burnell FLACs at 24bit 192 KHz.
In the middle are the charging and protection circuit for the battery and the wifi. Clockwise from the battery:
+ Lithium battery
+ Beagle Black and the DAC board
+ Amp board
+ Power supply (that is removable and in a separate enclosure.
Here are the KEF drivers I ended up using:
Everything is made from planks recovered at the beach 🙂
Here's the detail of the handle:
Detail of the driver guard:
The side view:
And how does it sound? I am impressed. I get about 6 hours of playing time before it starts to stutter and then I plug it in and in 15 minutes it's charged again 🙂. Quite pleased really. It is about 13 inches high and as you can imagine, most of the weight is in the cabinet. I chose only old cedar so it's not heavy at all.
Best of all, listening right now to Kenny Burnell FLACs at 24bit 192 KHz.
After breaking it in a bit, and tweaking the crossover for more bass, I can really recommend this little Sellarz DAC, perhaps it's because of DC power? Also makes me wonder if stereo is overrated. Now to convert mono records to hires FLAC..
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