Size?
It is hard to beat the little Tivoli Pal I have had for seven years. It cost me $100 back then and although needs a new battery it still sounds great.
I have the good old sonic impact hooked up to my boom-bike but it goes though batteries fast, ( still looking at battery pacs). It is loud enough with a 10" goldwood sub and 3" satellites to travel a block or fill just about any room. The $25 DVC sub is mounted in three ft. of 10" sonotube and has a 95db efficency so base is great but not what I would consider portable, it is mounted to a lowrider bicycle.
The key to good base is efficiency and then you need a large enclosure for any low output.
Pro sound plastic boxes are rugged, cheap and lite, some are water resistant also. I think one or two of those with a Amp6 and good battery would get you the most bang for the buck.
It is hard to beat the little Tivoli Pal I have had for seven years. It cost me $100 back then and although needs a new battery it still sounds great.
I have the good old sonic impact hooked up to my boom-bike but it goes though batteries fast, ( still looking at battery pacs). It is loud enough with a 10" goldwood sub and 3" satellites to travel a block or fill just about any room. The $25 DVC sub is mounted in three ft. of 10" sonotube and has a 95db efficency so base is great but not what I would consider portable, it is mounted to a lowrider bicycle.
The key to good base is efficiency and then you need a large enclosure for any low output.
Pro sound plastic boxes are rugged, cheap and lite, some are water resistant also. I think one or two of those with a Amp6 and good battery would get you the most bang for the buck.
Woa, this is really cheap für about 100Wh... Have you seen any measurements, whether the capacity really is as high as advertised?
Really, I wouldn't bother searching any cheaper for it
sorry i did not. i'm struggled by this, since it's usage is intended for video surveillance system: a system that turns on/off frequently, without a great power consumption.
instead of this, lately i'm looking into liion 18650 or rc batteries. the liion 4 cell packs are intended for flying little helicopters, so i think that their performance won't "fall" so much
having a look for those kind of accu, i found this:
5200mAh 14.8v 20C LiPo 4-Cell 14.8 RC Akku Battery WF su eBay.it Cars, Radio-Controlled, Toys Games
only doubt remains in the discharge rate i have to choose: i will feed two ta2020, and little chippery that goes on 3.7v input (read: an mp3 player, an headphone amp, a bluetooth receiver) - will a 20c accu do the work?
have you found something else interesting, more cheaper, r0b?
Isn't the 20C on a 5.2Ah battery ~100A or so (100A x 14.8V = 1.48kW)? I guess it is enough Those RC batteries can deliver huge amounts of current.
Does anyone know if those RC batteries can be paralleled and can they be charged with the same charger then? I would like to use four of the above mentioned ones or something alike.
Those RC batteries can deliver huge amounts of current.Does anyone know if those RC batteries can be paralleled and can they be charged with the same charger then? I would like to use four of the above mentioned ones or something alike.
Thats correct. However I highly doubt the ratings of such cheap batteries. Look at brand name LiPos. 14.8V 5200mAh 20C will run you 5-6 times as much as this one.
However even if it is really only 5C and 4000 mAh, that would still be 20A, so you should not have a problem.
You have to remember though that a 4S pack will output 16.8V fully charged, too much for T-amps I guess. A 3S pack will give you 12.6 fully charged to about 9V (3x3V) empty.
Paralleling packs is no problem, if they are the same capacity/type, and of equal age/usage state. You should get them all fully charged before connecting, and maybe sometimes disconnect them and charge them individually. Charging with a balancer every some cycles is a must anyway.
I got three of these DealExtreme: $6.68 TrustFire 18650 3.7V 2500mAh Rechargeable Lithium Batteries (2-Pack). Haven't tried em yet though. Problem is to get a battery holder. I ordered some of these DealExtreme: $1.98 UltraFire 2*18650/4*CR123A Battery Protective Case (2-Pack)
and will try to build myself some sort of battery holder with them. You can safely draw 2C from them, with true 2Ah, and 3s2p config, you would have 8 Amps. Definitely enough and about $20 for 12v/4Ah pack.
Try to see if you can get any reviews on the cheap batteries, to see if they really keep what they promise. On the other hand 20 pounds is worth a risk, and current will be coming out these too
Haven't really looked for much cheaper options, but I'm happy with the price I paid.
r0b
I like the ideas here. Class D/T is definitely the way to go there. I'm also working on a gel battery + soler panel combo.
The only thing that is a problem is making small enough and decent enough speaker(s) for this. I actually think that having it Mono won't be a problem either.
I like the ideas here and I definitely need to make something that is transportable in a backpack soon.
The only thing that is a problem is making small enough and decent enough speaker(s) for this. I actually think that having it Mono won't be a problem either.
I like the ideas here and I definitely need to make something that is transportable in a backpack soon.
Isn't the balancer a circuit that supervises the voltage of every individual cell connected in series? So if this 14.8V pack contains four cells in series (3.7V each) I can connect them in parallel with no problem, but as they are internally connected in series, I should maybe check that the pack contains a balancer? Longer life for the pack?
I would connect them in series via the power terminals, and also connect the balancer plugs. That way you would have 2 cells paralleled and 4 of these in series, as opposed to having 4 cells in series and two of these paralled.
1: + =-=-=-= -
2: + ==== -
That way each cell would be "buffered" with a parallel cells. In that config small differencen between the parallel cells would equalize themselves.
I think what you meant was how to charge though. Then of course you have to use option 1 (i.e. paralleling the balancer leads) since otherwise one pack would not be balanced, while the other one would be.
What I meant to say with "Charging with a balancer every some cycles is a must anyway.", is that it is not necessary to balance the pack every single charging cycle, if you have a simple charger for on the road for example.
1: + =-=-=-= -
2: + ==== -
That way each cell would be "buffered" with a parallel cells. In that config small differencen between the parallel cells would equalize themselves.
I think what you meant was how to charge though. Then of course you have to use option 1 (i.e. paralleling the balancer leads) since otherwise one pack would not be balanced, while the other one would be.
What I meant to say with "Charging with a balancer every some cycles is a must anyway.", is that it is not necessary to balance the pack every single charging cycle, if you have a simple charger for on the road for example.
indeed RC battery tech has progressed to such a rate that you could power a pretty powerful home full sized rig with it. I would use nanophosphate (lifepo4) instead of the lipo cells though, they dont have quite the energy density, but they charge quicker, are MUCH safer and lower noise/lower output impedance. A123 is the best brand for these. they will not explode if overcharged a bit and are not as easily damaged by undercharge. you can buy the cells singly and make your own balancer connector with a molex or similar, then either make your own regulated charger, or buy one of the chargers they use at RC meets. these LiFePo4 batteries are said to not show any degradation to the capacity after 1000 cycles and only at 90% capacity after up to 3000 cycles.
i'm using some for a portable buffalo II with balanced headamp
there is nolonger a valid claim that battery powered audio doesnt have the authority of power as home gear, with my battery pack being able to put out +/-10vdc (20v point to point nominal) at 2200mah, with a constant current rating of about 60A and a burst rate of up to 130A lol. these cells were developed for power tools, but the RC jets and helis they are running with these things are utterly insane. able to pull outside loops and pull up to a stop upsidedown a foot off the ground
i'm using some for a portable buffalo II with balanced headamp
there is nolonger a valid claim that battery powered audio doesnt have the authority of power as home gear, with my battery pack being able to put out +/-10vdc (20v point to point nominal) at 2200mah, with a constant current rating of about 60A and a burst rate of up to 130A lol. these cells were developed for power tools, but the RC jets and helis they are running with these things are utterly insane. able to pull outside loops and pull up to a stop upsidedown a foot off the ground
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I can't believe I just now found this thread.
I agree, a LiFePO4 4 cell battery would be an ideal solution for the Helder TA2020, to stay within the ideal voltage range; something like this...
LiFePO4 26650 Battery: 12.8V 6.8AH (87 Wh, 20A rate) built in PCB , Replace SLA with 10 times longer life & 61.77% lighter weight (8.16)
the built in PCB will keep the battery between 10 to 15.2 Volts.
I just found this. You can get some 18650 holders here... Digi-Key - BK-18650-PC2-ND (Manufacturer - BK-18650-PC2)
or from this guy... DIY 18650 Li-Ion Cell Holders - New Stuff... see thread bottom - CandlePowerForums
This is a good place to buy very decent LiPo packs in just about any size or shape ... HobbyKing Online R/C Hobby Store :
I have this charger (for Li-ion, and LiFe) and it works great!...
HobbyKing Online R/C Hobby Store : Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories
These are some great connectors...
HobbyKing Online R/C Hobby Store : Traxxas style Plug Male & Female (10pairs/set)
Anyone ever think about making some speakers out of Polycarbonate bottles like this... www.nalgene-outdoor.com - Detail
I still have a few of the older ones that were still made out of polycarbonate, not the newer copolyester.
or something like this... (may be too thin?)
Cambro Food Storage Containers / Round / Clear Polycarbonate / Boxes / 1 to 22 Quart Capacities by Cambro - Restaurant Equipment and Restaurant Supplies at Zesco Products
I agree, a LiFePO4 4 cell battery would be an ideal solution for the Helder TA2020, to stay within the ideal voltage range; something like this...
LiFePO4 26650 Battery: 12.8V 6.8AH (87 Wh, 20A rate) built in PCB , Replace SLA with 10 times longer life & 61.77% lighter weight (8.16)
the built in PCB will keep the battery between 10 to 15.2 Volts.
I just found this. You can get some 18650 holders here... Digi-Key - BK-18650-PC2-ND (Manufacturer - BK-18650-PC2)
or from this guy... DIY 18650 Li-Ion Cell Holders - New Stuff... see thread bottom - CandlePowerForums
This is a good place to buy very decent LiPo packs in just about any size or shape ... HobbyKing Online R/C Hobby Store :
I have this charger (for Li-ion, and LiFe) and it works great!...
HobbyKing Online R/C Hobby Store : Turnigy Accucel-6 50W 6A Balancer/Charger w/ accessories
These are some great connectors...
HobbyKing Online R/C Hobby Store : Traxxas style Plug Male & Female (10pairs/set)
Anyone ever think about making some speakers out of Polycarbonate bottles like this... www.nalgene-outdoor.com - Detail
I still have a few of the older ones that were still made out of polycarbonate, not the newer copolyester.
or something like this... (may be too thin?)
Cambro Food Storage Containers / Round / Clear Polycarbonate / Boxes / 1 to 22 Quart Capacities by Cambro - Restaurant Equipment and Restaurant Supplies at Zesco Products
I have just found this thread and I hope that you still have a interest in it. I bought about half a dozen of your cheap ta2024 (which sound amazing), paired them with a 12.6v 4800mah cctv battery and whatever speaker I can, buy a cheap pair of $1 headphones for the jack. So far, I've made 6, all of which sound better than anything that you can get at a store and for a fraction of the price. I will post pictures soon.
My concern is that I had to bypass the circuits on the battery. For whatever reason, it would power down when I turned on the amplifier. so i removed the circuits on top of the cells and remade the pack. I was using 6 "C" cells, and I can say that it's definitely louder. I'm just worried about using lithium batteries without a protection circuit.
Also, what would be a good pre-amp for the ta2024 or ta2020? I'm interested in using them in a guitar amplifier as well. I like the
Oatley Electronics
Although it's a little steep for a college budget.
Im now working on a 2X 3 watt amplifier on 3.8 V it will have the following things inside,
- Dc-DC converter to convert to 5V ( gives the amplifier maximal power )
- Solar charger connect your solar panel and check the charge status with 2 LED's
- 2X mono 3 watt class-D ic ( PAM8303D )
- battery indicator with 4 LED's
- size is 45X55mm
ill show a photo of a prototype when available.
Greetings!
arjen
- Dc-DC converter to convert to 5V ( gives the amplifier maximal power )
- Solar charger connect your solar panel and check the charge status with 2 LED's
- 2X mono 3 watt class-D ic ( PAM8303D )
- battery indicator with 4 LED's
- size is 45X55mm
ill show a photo of a prototype when available.
Greetings!
arjen
its always bad to trust the IC manufacturers specifications, they are never as good as promised, so measuring the real output is essential.
for the PAM8303D i measured less than 1% THD at 2.5 Watt over 4 Ohms, with good speakers for a portable application that is really quite good! and if you want more sound, another option is to use this kind of IC in parallel and add another speaker. then you can end up with 4 speakers instead of 2.
for me a truly portable design is something with solar, that can recharge where ever. and also play straight off the sunlight.
my PCB has been ordered, im eager to show results~!
for the PAM8303D i measured less than 1% THD at 2.5 Watt over 4 Ohms, with good speakers for a portable application that is really quite good! and if you want more sound, another option is to use this kind of IC in parallel and add another speaker. then you can end up with 4 speakers instead of 2.
for me a truly portable design is something with solar, that can recharge where ever. and also play straight off the sunlight.
my PCB has been ordered, im eager to show results~!
Arjen, I think your idea is great. An ultra-portable and rechargeable unit, looking forward to seeing it completed. I'm curious as to what speakers you'll pair with this unit. Ultra efficient...maybe 90db/w/m+? Maybe 5"? I'm guessing that the box design would be really important too.
Are you planning to sell this board?
-Nicholas
Are you planning to sell this board?
-Nicholas
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