Best 5v speakers

Many external powered speakers are powered by 6v wall adapters, easily regulated to 5v.

And 6v is a common enough adapter that even if the speaker supply is

I see some LDO's but the current supported seems to be quite low (0.5A). Can I put two in parallel to convert to 5v 1A? (I don't know anything about electronics :) )

Yes, I see there are quite a few, thanks! :)

Putting regulators in parallel is in general a Bad Thing. They all have a very slightly different output voltage, i.e. point at which they try to regulate, because of inevitable production tolerances. The consequence is that the regulator with the highest output voltage tries to supply all the current, which it does until it goes into current limit, and then the on with the next lowest output voltage will start contributing, etc.

The current is not shared equally between the regulators, in other words. Some will be more highly stressed than others.

Dave

Although paralleling 'same voltage output' smpsus to boost current rating is generally a bad idea. This arrangement can be used with smpsus designed to safely operate indefinitely in current limited mode (designs with well defined maximum output ratings that don't overstress any of its components) and also designed to tolerate being hooked up to a power bus that can vary above their set voltage by a reasonable margin beyond the normal range of preset voltages used by their peers.

A system comprised of a bank of such smpsus can be arranged so that as the load demand increases, successive smpsus will cut in to stabilise the voltage at a slightly lower level (usually a few millivolts drop for each successive smpsu).

Assuming a bank of 5 10amp rated 12v smpsus numbered 1 to 5 are provided to service a load that varies from less than ten amps to a max of 50 amps with smpsu 1 set for 12.04v, smpsu 2 set for 12.03 and so on with smpsu 5 set to 12.00v we can wire each of them up to the mains with a suitably calibrated ammeter to display full deflection at max output and emulate the metering scheme shown in the movie "Forbidden Planet".

This may have been a practice with mainframe computers for a form of redundency and modularisation (but without the "Forbidden Planet" metering effect and, therefore without any need to calibrate output voltage to achieve a predetermined cut in effect). However, I might just be making this bit up... Time to google.

The only reference I could find to paralleling DC supplies was near the bottom of this page:

Not exactly what I was looking for. Perhaps someone else with a knowledge of mainframe power systems might be able to offer a clue.

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Regards, J B Good

You're probably best looking the other way around - find USB _powered_ speakers and then power both from the same self-powered hub. Note that clarification - strictly USB speakers essentially have a soundcard built into them, you want the simpler kind with an analog audio connection, e.g.

or

--
Andrew Smallshaw 
andrews@sdf.lonestar.org

Hi Andrew,

Yes, that's my current set up with a Airpot Express that outputs audio and current to a set of those speakers, but the audio is really low quality.

So I was looking to build something my self for a bit better quality, eventually with a box big enough to insert the RPi in, or simply paste it at the side with some dual-faced tape. :)

I will continue to search and let you all know if I find something average that could be used for this.

Thank you, Marco.

Anything that lives of 5 V is never going to be all that good. There just isn't the energy available 5^2/4 = 6.25 W at the very best. Why bother spending money on decent drivers, cabinets, etc ...

That would be the way to go, presumably the 5 V @ 2 A requirement is to power the RPi? Or get some decent self (mains) powered speakers and either fit a suitable DC-DC convertor on the the DC rail for the amp or a USB power supply across the mains for the RPi. You may be able to find powered speakers with both amps in one box and the other box just has a speaker connection.

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Cheers 
Dave.

I'd not invest too much money in them - the audio quality from the 3.5mm jack is not very high due to the way its created.

Gordon

Hi Gordon,

Yes I start to think the way to go is having a DC-DC converter (ex.:

12->5v) to avoid having two power adaptors, and paste the RPi inside or on the side.

I have a pair of PC speakers from JBL (14W "Media 3") with an active subwoofer, and maybe I'll dig a bit into them to see if they suit my immediate needs. :)

Cheers.

What do you all think about this? Is it to work without introducing significant noise?

3.5mm jack

Yes, defiantly not, unless there was a way to use the jack or GPIO to output S/PDIF... :)

I didn't write the post you're replying to.

Gordon

There is no way to tell about the noise unless you buy one and hook it up. But you realize that this uses 12 volt power as the source and produces 5 volts? I thought you were looking for something to up the 5 volt supply to 12 volts for an amplifier?

The problem Dave is describing is the fact that to drive speakers to significant power levels, you need a higher voltage than 5 volts. But you also need the power. 5 volts at 2 amps is 10 watts. It won't matter if you up the voltage to 12 or 24, the 5 volt, 2 amp power source will always be limited to 10 watts. However, 10 Watts is not a low volume. If you actually get 10 Watts into your speaker, that is a significant power level.

What is your power source for this project? How loud do you need this to be? I can't imagine there aren't products out there to do exactly what you want without cobbling together a jury rig. If there's not, let me know and I'll design something and sell it :)

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Rick

Of course, there are plenty of H-bridge speaker amps, which could provide about 25w to a 4-ohm speaker. A transformer (unlikely in small speakers) would also allow significant power to be delivered.

I assume, since the OP asked about PC speakers, that a few watts was plenty. (That and the 6v, 1A presumed speaker power supply--with 1A for the rPi.)

--
-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon

ER no.

10v peak to peak is about 3.8v rms or 3.7W rms into 4 ohms: From 5V in H bridge.

Roughly speaking you can 5W from a 12v car supply or in bridge 25W at 'full charge' 13.8v by bending the numbers a little

how LOUD is far more about the speaker itself than the power. there can be 20:1 ratios in loudness between different loudspeakers at similar power

--
Ineptocracy 

(in-ep-toc?-ra-cy) ? a system of government where the least capable to  
lead are elected by the least capable of producing, and where the  
members of society least likely to sustain themselves or succeed, are  
rewarded with goods and services paid for by the confiscated wealth of a  
diminishing number of producers.

Sim I'm not a electronics guy, I'll try to keep it simple and low-cost.

The idea is to use the same power-supply from the speakers to power the RPi, and since these JBL I have here are 13.5v I was looking to extract from it 5v for the RPi.

But thank you for the help. I might come back with some electronic (dummy) questions. ;)

a fairly simple linear or switching regulator will do that for you.

The ones made for radio control models are useful - they take a typical flight battery in the range of 8-40V or so and down convert to a respectable 5V with serious current capability to drive servos etc. Normally built into the speed controller forte electric motors, but they are available standalone.

They are very low noise - have to be to work with sensitive SW and UHF radio..

is a very neat device designed to be pin compatible with a typical linear 5v regulator.

I have used the company before - top quality design engineers.

--
Ineptocracy 

(in-ep-toc?-ra-cy) ? a system of government where the least capable to  
lead are elected by the least capable of producing, and where the  
members of society least likely to sustain themselves or succeed, are  
rewarded with goods and services paid for by the confiscated wealth of a  
diminishing number of producers.

First you would need to check that the JBL power supply has the capacity to handle an additional load.

The simplest form of regulator would be a linear. Assuming about 300mA for the pi (i.e. nothing plugged into its USB ports), that would mean

4 watts split between the pi and the regulator. Of that about 2.5 watts goes into the rergulator, so you would need a pretty highly rated one and equip it with a heatsink. (The 1 amp 7805 type won't cope with the heat - it will keep shutting down as it overheats.)

You would be better using a switch-mode converter. I don't know of specific models, but as the requirement is identical to powering USB devices from a car, they should be fairly easy to find.

--
Alan Adams, from Northamptonshire 
alan@adamshome.org.uk 
http://www.nckc.org.uk/

None of the mainframes I used (ICL 1900 and 2900/3900 systems) had redundant power supplies: it was just that each box in a system (DFC, disk drive, OCP, bank of tape decks, etc) had its own power supply and the computer room might, if you were lucky, have a UPS capable of running everything in the room.

However, the fault tolerant kit I've used (Tandem NonStop [now HP NonStop] and Stratus [also badged as the IBM System/88]) all came with dual power supplies. Normally both would be running, but either could fail and leave the system running on the remaining PSU.

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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
org       |