Hello there,
I am entirely new to chip amps but have done some PCB and P2P assembly on tube amps before.
I want to build a high quality, battery powered amp + speaker that I can take around and sounds better than my run-of-the-mill Cambridge Audio USB speaker, but need not compete with my 300B SET.
My parameters:
- Battery powered. Ideally I would like to use my DeWalt power tool batteries. I have a few 20V, 1.5Ah Li-Ion batteries and charger, and probably could buy a higher-capacity model if needed. I could scrape a broken tool "for parts" to get the battery shoe and attach it to the sound system.
- Mono. Rather than cramming 2 channels in a small box, if I wanted a true stereo image I'd rather build 2 of these. But that is not a concern at the moment.
- Loud enough. The reason I'm starting this project is that my USB loudspeaker proved absolutely inadequate for an open-air dance session that I recently set up.
- Compact. Ideally a 8"-10" cube.
- Good sounding but not necessarily "audiophile" grade. I have my Hi-Fi set up in a quiet room for that.
- Decent life: at least 1 hour operation at high volume per battery (30Wh).
- Reasonably priced: if possible, under $150 with loudspeakers (hoping to save on batteries by using my DeWalt ones).
Where shall I start? I read some threads about Gainclone which seems to be a good candidate, and even saw some kits with and without IC on eBay at affordable prices (even for eBay). But the options and variations seem overwhelming to me. Which chip shall I use? How do I pair chip, battery voltage, and loudspeaker(s)? Any good tutorials to read for understanding the basic parameters?
Thanks a lot for the advice.
gm
I am entirely new to chip amps but have done some PCB and P2P assembly on tube amps before.
I want to build a high quality, battery powered amp + speaker that I can take around and sounds better than my run-of-the-mill Cambridge Audio USB speaker, but need not compete with my 300B SET.
My parameters:
- Battery powered. Ideally I would like to use my DeWalt power tool batteries. I have a few 20V, 1.5Ah Li-Ion batteries and charger, and probably could buy a higher-capacity model if needed. I could scrape a broken tool "for parts" to get the battery shoe and attach it to the sound system.
- Mono. Rather than cramming 2 channels in a small box, if I wanted a true stereo image I'd rather build 2 of these. But that is not a concern at the moment.
- Loud enough. The reason I'm starting this project is that my USB loudspeaker proved absolutely inadequate for an open-air dance session that I recently set up.
- Compact. Ideally a 8"-10" cube.
- Good sounding but not necessarily "audiophile" grade. I have my Hi-Fi set up in a quiet room for that.
- Decent life: at least 1 hour operation at high volume per battery (30Wh).
- Reasonably priced: if possible, under $150 with loudspeakers (hoping to save on batteries by using my DeWalt ones).
Where shall I start? I read some threads about Gainclone which seems to be a good candidate, and even saw some kits with and without IC on eBay at affordable prices (even for eBay). But the options and variations seem overwhelming to me. Which chip shall I use? How do I pair chip, battery voltage, and loudspeaker(s)? Any good tutorials to read for understanding the basic parameters?
Thanks a lot for the advice.
gm
you mean 15 Ah, eh!?!
It needs dual rail supply, you shall put two of those 20 V batteries in series
But, being 1.5 Ah, they won't last long.
You'll be directed to low cost ( being already assembled and retailed in big numbers ) class D amplifiers, which work well with those voltage supply and are very efficient compared to B/AB class amps.
The stereo package allows to use one amplifier for the woofer and one for the tweeter/fullrange. This leads to my kind of response: I'd use a 10" woofer and a compression driver for the tweeter ( it needs a horn).
The stereo setup would allow some 'spaciousness', gain in the low frequencies, 'imaging'.
The woofer seems difficult to find...something in the 94 dB league, so a Pro woofer, which sacrifices a little in low bass extension but gains in efficiency, so the tweeter must not be totally attenuated *( compression drivers are far more sensitive).
Ehy, it took me at least 20 years to digest those technical terms, so don't be in a hurry!
*This does not make sense in an active set-up like the one mentioned, i.e. stereo amps serving one channel with one amplifier driving the woofer and the other driving the tweeter...which is not even necessary if you use a CD tweeter.
Woofer(boxed) and a 3" fullrange would work, the crossover point varies ( uh! I nominated a crossover!)
The woofer seems difficult to find...something in the 94 dB league, so a Pro woofer, which sacrifices a little in low bass extension but gains in efficiency, so the tweeter must not be totally attenuated *( compression drivers are far more sensitive).
Ehy, it took me at least 20 years to digest those technical terms, so don't be in a hurry!
*This does not make sense in an active set-up like the one mentioned, i.e. stereo amps serving one channel with one amplifier driving the woofer and the other driving the tweeter...which is not even necessary if you use a CD tweeter.
Woofer(boxed) and a 3" fullrange would work, the crossover point varies ( uh! I nominated a crossover!)
Ciao,
I wish it was. They have these very expensive ones that go up to 9Ah: https://www.homedepot.com/p/DEWALT-...AX-Lithium-Ion-9-0Ah-Battery-DCB609/300610594 But if I had to buy that it would void the purpose of using batteries I already have.
Maybe I can't really squeeze out much more power than my USB speaker with that kind of battery?
I wonder if I could find a circuit that works with a 6V battery like this: https://www.mouser.com/datasheet/2/95/dow01404181781-910180.pdf A bit heavy, but still compact enough and not too expensive. However I can't board a plane with it.
Shall I move this thread to the Class D forum?
10" and horn sound like a home theater / HiFi setup that won't fit my project. I was eyeing whatever subwoofer is most efficient in the <=6" range.
you mean 15 Ah, eh!?!
I wish it was. They have these very expensive ones that go up to 9Ah: https://www.homedepot.com/p/DEWALT-...AX-Lithium-Ion-9-0Ah-Battery-DCB609/300610594 But if I had to buy that it would void the purpose of using batteries I already have.
Maybe I can't really squeeze out much more power than my USB speaker with that kind of battery?
I wonder if I could find a circuit that works with a 6V battery like this: https://www.mouser.com/datasheet/2/95/dow01404181781-910180.pdf A bit heavy, but still compact enough and not too expensive. However I can't board a plane with it.
Shall I move this thread to the Class D forum?
10" and horn sound like a home theater / HiFi setup that won't fit my project. I was eyeing whatever subwoofer is most efficient in the <=6" range.
Hi, for your project you should look at the e-bike batteries, which are Lithium batteries and each battery is about 3.2 V with current from 1500 to 3500 mA.
Then you need a Battery Management Supply, BMS, to monitor each battery during charge and discharge.
The market now moves to 48 V batteries ( 13-15 in series, then each is a parallel of 2-3-4 batteries ) so you should find easily some old ones ( but...with a battery- who knows? ) in the 24 V category.
Those should cost you much less. You need just the bare battery pack ( which incorporates the BMS) and the charger.
About the speakers- Quite the opposite: in open space you need some big speakers. I cannot use my old 10" because they're too big ( and awful) in the room. Last summer I made a 'party rig' with some leftovers -the two 10" and two little CDs I bought some years ago for tryin' ( they sounded horrible).
The crossovers were from two Boston speakers and the amplifier an old Pioneer with 20W chip ( STK series). It worked ( and works) like a charm...if only that rusty switches would like to conduct a little more
Then you need a Battery Management Supply, BMS, to monitor each battery during charge and discharge.
The market now moves to 48 V batteries ( 13-15 in series, then each is a parallel of 2-3-4 batteries ) so you should find easily some old ones ( but...with a battery- who knows? ) in the 24 V category.
Those should cost you much less. You need just the bare battery pack ( which incorporates the BMS) and the charger.
About the speakers- Quite the opposite: in open space you need some big speakers. I cannot use my old 10" because they're too big ( and awful) in the room. Last summer I made a 'party rig' with some leftovers -the two 10" and two little CDs I bought some years ago for tryin' ( they sounded horrible).
The crossovers were from two Boston speakers and the amplifier an old Pioneer with 20W chip ( STK series). It worked ( and works) like a charm...if only that rusty switches would like to conduct a little more
You did say open air dance session, correct? I'm trying to imagine something " <=6" " as possibly being adequate, regardless of how much power you throw into it. "Open air" being the operative environment - not inside a car cab, nor inside a room where you can count on some gain for the sound stemming from the speaker being within an enclosed space.
Outside typically means big, regarding loudspeakers and the 10" suggestion is entirely appropriate in order to get something / anything your dancers are going to be moving to.
If I were doing it, I'd make it modular. You could build it around the ZOUDIO AIO4CH: 4-channel amplifier with DSP and Bluetooth
One box holding the suggested 10" / Tweeter, running mono. A second box with the same, optional depending on your luggage and if you want stereo. A third box containing even a bigger speaker / pair, as a sub for that beat to get your dancers feet moving. Depending on how many friends you have about at the time, the system could be 1, 2, or 3 speakers, mono or stereo. Read through the thread - BT to your music source (Phone / PC / Pad)
The spec says 4 X 45W and you want to run at least an hour, so we''l say 1.5 hours as we know how these things (dances) go. We'll also guess 75% ultimate max capacity as a continuous amplifier power output. So that's 135W for 1.5 hours or ~200W-H of energy to be provided. The amp takes ~24V which could be had via a string of batteries. 24 goes into 200 about 8 times, so each of your batteries adding up to 24V would need to be ~8A-H capacity.
On ebay they have these Lithium ECO 8AH 24AH 12V LiFePO4 Rechargeable Lithium Iron Phosphate Battery for RV Boat | eBay batteries for ~$100 for two, of the voltage and about the capacity you'd need. Just that and the Zoudio amp exceeds your budget unfortunately (~$200)...
With the modular approach, you could construct in increments, but I'd say you're looking at perhaps $300 to get started for amp, speakers, battery, cabinet wood and wiring. Try the mono system and imagine how it'd sound doubled by adding the 2nd speaker. But remember, then you can only play and party half as long (1.5 hours with all 4 channels running @ 135W, versus 3 with just two channels using half the power)!
Good Luck!
Outside typically means big, regarding loudspeakers and the 10" suggestion is entirely appropriate in order to get something / anything your dancers are going to be moving to.
If I were doing it, I'd make it modular. You could build it around the ZOUDIO AIO4CH: 4-channel amplifier with DSP and Bluetooth
One box holding the suggested 10" / Tweeter, running mono. A second box with the same, optional depending on your luggage and if you want stereo. A third box containing even a bigger speaker / pair, as a sub for that beat to get your dancers feet moving. Depending on how many friends you have about at the time, the system could be 1, 2, or 3 speakers, mono or stereo. Read through the thread - BT to your music source (Phone / PC / Pad)
The spec says 4 X 45W and you want to run at least an hour, so we''l say 1.5 hours as we know how these things (dances) go. We'll also guess 75% ultimate max capacity as a continuous amplifier power output. So that's 135W for 1.5 hours or ~200W-H of energy to be provided. The amp takes ~24V which could be had via a string of batteries. 24 goes into 200 about 8 times, so each of your batteries adding up to 24V would need to be ~8A-H capacity.
On ebay they have these Lithium ECO 8AH 24AH 12V LiFePO4 Rechargeable Lithium Iron Phosphate Battery for RV Boat | eBay batteries for ~$100 for two, of the voltage and about the capacity you'd need. Just that and the Zoudio amp exceeds your budget unfortunately (~$200)...
With the modular approach, you could construct in increments, but I'd say you're looking at perhaps $300 to get started for amp, speakers, battery, cabinet wood and wiring. Try the mono system and imagine how it'd sound doubled by adding the 2nd speaker. But remember, then you can only play and party half as long (1.5 hours with all 4 channels running @ 135W, versus 3 with just two channels using half the power)!
Good Luck!
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Thanks for all the suggestions so far.
Portability (and hence efficiency) is the main challenge here. I realize there will be compromises to make, otherwise I would go with one of those "trolley" speaker systems that street musicians use.
It's a dance performance, but very contained. 2 people in a 3x3m (10') area, with as much as a dozen watchers on the sidelines. We managed to pull off a decent session even with this skimpy speaker, so I guess that I'm looking somewhere in between these two extremes.
I could try to fit an 8" driver in a shallower design (but of course an 8" has some depth too, plus the battery) but that would be the limit. The e-bike battery sounds like a good idea.
Portability (and hence efficiency) is the main challenge here. I realize there will be compromises to make, otherwise I would go with one of those "trolley" speaker systems that street musicians use.
It's a dance performance, but very contained. 2 people in a 3x3m (10') area, with as much as a dozen watchers on the sidelines. We managed to pull off a decent session even with this skimpy speaker, so I guess that I'm looking somewhere in between these two extremes.
I could try to fit an 8" driver in a shallower design (but of course an 8" has some depth too, plus the battery) but that would be the limit. The e-bike battery sounds like a good idea.
What about pairing a 15+15W T-Amp with a 90+db efficient two-way car speaker or even a full-range one?
The amp board needs 12V @2A so if I got the math right, the 8Ah e-bike battery that @jjasniew mentioned I should get about 4 hours usage at full blast—correct?
The amp board needs 12V @2A so if I got the math right, the 8Ah e-bike battery that @jjasniew mentioned I should get about 4 hours usage at full blast—correct?
I don’t have room in my briefcase for batteries, but the small Class D (TI) chip amp plus a pair of uMar-Ken6, with either my Mac or iPhone as a source produces fantastic sound — even ignoring that it all fits in a haliburton briefcase.
It could run off batteries, or maybe even a solar panel.
dave
It could run off batteries, or maybe even a solar panel.
dave
The Alpair 6-M look really nice and compact. Also, I found the thread on traveling speakers where you mention them. Nice thread. Thanks.
If I could splurge on the speakers I would look into the Audio Nirvana 8" which are much larger but also much more efficient than the Alpairs, so I could save on battery space & weight with a less hungry amp.
About the TI chip—do you have any schematics for a complete amp design?
If I could splurge on the speakers I would look into the Audio Nirvana 8" which are much larger but also much more efficient than the Alpairs, so I could save on battery space & weight with a less hungry amp.
About the TI chip—do you have any schematics for a complete amp design?
OK, I found a pair of Alpair 7MS at a good price, which seem an improvement from the 6.2 which is categorized as a "near-field" speaker. I'll try to pair them up with a Tripath TA2024 (2 x 15W) and see how it fares in the open. The Alpairs are so small that I can easily build 2 small cabinets + an enclosure for the amp and battery, and arrange them apart for an actual stereo image.
Saw this in another thread; PRV Audio 10FR300PR 10" Professional Full-Range Speaker 8 Ohm
"Extremely efficient (100 dB) for high output without a lot of power" MMMmmmmm! That maybe makes your battery last longer than you (or anyone else) can dance. No need for tweeter / crossover too. $66 with free ship -
Maybe 8 Ohm is a problem. Oh well...
Sounds sweet, however 10" is too large for my project.
True. My reasoning was that I could start with a 7 mono. But I actually got a pair of 6M too since they are reasonably priced and I could always repurpose them.
The problem with the mono setup is that the board I got seems to not like mono wiring: T-Amp Tripath TA2024 2 x 15W Audio Digital Amplifier Board However I guess that could be resolved with a soldering iron... right?
Regarding batteries, would a car jump starter, e.g. this one, work as a power supply for the amp?
Maybe the term "jump starter" scares me a bit, and I see that that model can charge phones and tablets through the 5V USB port, but the 12V supply is for jump starting cars, so I wonder if I should worry about any power paks that may burn out my amp...
Maybe the term "jump starter" scares me a bit, and I see that that model can charge phones and tablets through the 5V USB port, but the 12V supply is for jump starting cars, so I wonder if I should worry about any power paks that may burn out my amp...
Directly connected, any 12V battery with the A-H rating you need for a good run-time has the capacity to burn up your amp. You have to protect it with a fuse. The advantage of the jump start kit is you can use it as a jump start for your car, when not using it to power your sound system. However,
I see it doesnt come with a charger, so no advantage there. They dont really say very clearly how the thing gets charged; "just use this or that". Ok, _how_? Through the USB port? Does it have a charging port? What kind of connector? Where do you get the cigarette lighter plug? Smells of "one time use" to me...
The jump cables have the "smart box", which doesnt electrically connect the jump starter battery unless it "sees" certain conditions (perhaps at least some voltage on the "dead" car battery), so you'll have to engineer a way around that (even if it's just cut-off that part from the jump cable set... Before wiring to your amplifier through a fuse of a couple-few amp rating.)
You could probably make it work. 6A-H would run your amp for some time. $30 is pretty good - but be careful; there's a lot of energy in it as an obviously cheaply made piece. I've read at least one customer review where one of these glove box jump start devices burned up spontaneously on his cement garage floor. He showed an after picture...
Of course, the ebay Lithium battery as a component could start a fire too, but at least the ownership there is on you (how thoughtfully you connect wires to it, how you charge it, etc) and not some random manufacturer in China cranking 'em out for $15-$20 a pop.
I mean it'll probably be OK - but there's some things to consider. Err on the side of caution. Maybe one of the jump start kits with a 12V lead acid battery - if they even still make them anymore since these miniature Lithium ones came along - would be safer.
I see it doesnt come with a charger, so no advantage there. They dont really say very clearly how the thing gets charged; "just use this or that". Ok, _how_? Through the USB port? Does it have a charging port? What kind of connector? Where do you get the cigarette lighter plug? Smells of "one time use" to me...
The jump cables have the "smart box", which doesnt electrically connect the jump starter battery unless it "sees" certain conditions (perhaps at least some voltage on the "dead" car battery), so you'll have to engineer a way around that (even if it's just cut-off that part from the jump cable set... Before wiring to your amplifier through a fuse of a couple-few amp rating.)
You could probably make it work. 6A-H would run your amp for some time. $30 is pretty good - but be careful; there's a lot of energy in it as an obviously cheaply made piece. I've read at least one customer review where one of these glove box jump start devices burned up spontaneously on his cement garage floor. He showed an after picture...
Of course, the ebay Lithium battery as a component could start a fire too, but at least the ownership there is on you (how thoughtfully you connect wires to it, how you charge it, etc) and not some random manufacturer in China cranking 'em out for $15-$20 a pop.
I mean it'll probably be OK - but there's some things to consider. Err on the side of caution. Maybe one of the jump start kits with a 12V lead acid battery - if they even still make them anymore since these miniature Lithium ones came along - would be safer.
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