I have a Bose Companion 5 Subwoofer. The power supply is sealed inside the cabinet. I have access to 2 pairs of wires: AC-in DC-out. How do I measure the maximum output of the PSU?
The start should be to define what you mean by 'maximum output'. One suggestion would be to measure the unloaded output, then connect lower and lower resistance values, increasing the load, until the voltage drops, say, 5%.
Jan
Jan
It isn't easy to find if you are far from electronics. It may involve temperature and ripple measurements etc.
if the amplifier is designed for short dynamic peaks, the power supply may drop by a lot more than 5%. I recently repurposed a power transformer from a 5 Channel 100 watt per channel AV receiver. The power supply capacitor was only 8200uF + 8200uF.
Short answer, you can´t.
Method suggested above can give you a *rough* approximation with an unregulated linear supply; being a modern product I BET it has an SMPS.
Voltage will be rock steady until some internal protection triggers and it shuts down.
Your question is very fuzzy and generic, will only get fuzzy and generic answers; if you told us your actual purpose we might guess better.
As in: if you want to feed an external peamp or processor, it will probably do.
If you want to feed an external power amp, it will not.
You do not even give us the voltage involved, let alone the schematic.
If that's the case, then - assuming it's a switch mode power supply - measuring the efficiency curve (involving simultaneous measurement of Iin, Vout and Iout [assuming Vin is pretty much constant] would certainly be beyond what you'd want to be bothered with.
Regardless, you'd get an efficiency Pout/Pin X 100 vs Pout curve. It would ramp up with increasing Pout toward something like "90%" (by decreasing the resistive load) then go down somewhat. Finally, the PSU would hopefully shut down due to an overload condition.
The point where the power supply is most efficient is probably close to the "maximum output" the unit was designed to deliver. Of course, this is guarded by it being able to provide a bit more power, at the expense of efficiency, maybe 20% more.
(I used to write automated testing for this - it's easy with dataloggers, electronic loads and AC sources that have GPIB interface to a computer. I completely understand it's bit difficult to do manually, as that was the basis of my employment.)
Last edited:
+1. Such question may have a simple solution if there is somebody who definitely knows the answer.
Otherwise we may only guess.
Not at all. You can do the equivalent of a binary search. 4 or 5 iterations should get you there.
But as I said, first decide what you mean by 'max power'.
Jan
Okay . . . Let me break it down.
(1) There will be no schematic, ever - It's made by BOSE!
(2) The Bose Companion 5 makes no specific claims beyond [maximum power 300w] Bose companion 5 and Power rating input. - Bose Community - 154569
(3) In the design of the cabinet Bose has sealed the PSU inside. It is impossible to access the driver or PSU without destroying the cabinet. The amplifier board is at the back and can be accessed.
(4) I have one of these (originally 2.1) systems without the amplifier. I have replaced the original amp with a TPA 3116D2 to power the dual coil bass driver.
(5) I am sceptical as to Bose's power claims but if I am wrong there is enough power for the TPA3116D2 to deliver 240w to the meagre 5" bass-driver, an amount I believe could prove fatal! If Bose's 300w claim is measured in PMPO, down-hill with wind behind, then I'm guess I'm okay. But if the original amp and PSU were capable of delivering 300w RMS - I'm in trouble.
The tpa3116 has an absolute max rating of 26VDC. Before you hook it up to the Bose power supply. Make sure the voltage does not exceed that value. The max power you can pull out of a single TPA3116 is 100watts @2 ohm load. So don't worry about exceeding the speakers power rating.
You can connect kilowatt amplifiers to 10 watt speakers and visa versa. Just be carefull with the volume control.
You can connect kilowatt amplifiers to 10 watt speakers and visa versa. Just be carefull with the volume control.
The 300W rating is maximum power consumption, not output power.
The power supply will have bulk decoupling capacitors so 300W is not an instantaneous value but a longer term value.
It is not necessarily however a continuous rating.
What you can determine, by practical testing with a DMM, is the current consumption of your new amplifier at different listening levels. Measure the current draw in the +ve lead from the power supply to the TPA3116 board. You may be surprised at how little power you require to shake the room, depending on speaker efficiency.
The power supply will have bulk decoupling capacitors so 300W is not an instantaneous value but a longer term value.
It is not necessarily however a continuous rating.
What you can determine, by practical testing with a DMM, is the current consumption of your new amplifier at different listening levels. Measure the current draw in the +ve lead from the power supply to the TPA3116 board. You may be surprised at how little power you require to shake the room, depending on speaker efficiency.
You´d be surprised!!!! 😎
FWIW I have the Bose PS1 power supply service manual and it´s a 34 page PDF.
Calling it a complex PSU is the understatement of the year.
That´s just the recommended outlet rating to use, not even full power consumption.
It could easily include a 2:1 safety margin so no more than 150VA real consumption.
A very fuzzy rating.
But still you have NOT told us supply voltage 🙄
You should have ALSO mentioned that. 🙄
What is each voice coil DCR?
How are they connected?
What is the amplifier load?
That is an IMPORTANT question.
Who knows?
We don´t know VOLTAGE or IMPEDANCE.
Who knows?
We don´t know VOLTAGE or IMPEDANCE.
Answer VOLTAGE and IMPEDANCE and we can guess your TPA3116 health and life expectancy.
But not without data.
Last edited:
Seriously, I appreciate your efforts. But I was seeking the advice of experienced people. If I had all the data I could use Excel and the question would be moot.
Experience and 'rule of thumb' governs 'likelihood'. An appliance using 100v A/C using a 3amp fuse cannot consume [headroom] more than 300w. Assuming standard ineffeciencies, a device consuming 300w cannot output more than 200w. At 12v the power supply would need to be rated @ 25 amps plus . . .
Experience and 'rule of thumb' governs 'likelihood'. An appliance using 100v A/C using a 3amp fuse cannot consume [headroom] more than 300w. Assuming standard ineffeciencies, a device consuming 300w cannot output more than 200w. At 12v the power supply would need to be rated @ 25 amps plus . . .
You got exactly what you sought. The advice of (very) experienced people. Your refusal to believe or accept that advice in no way changes the validity of the advice.
If you think a 3A fuse stops conducting at 3A you're mistaken.
There is no such thing as a "standard" efficiency. Surely 66% is low on the efficiency scale these days. Most class D amps, SMPS, boost converters, buck converters etc are more than 90% now.
I've built many tube amps that have run from a 12V ATX supply. My current model will supply 90A. It's also about 88% efficient.
The first advice was good advice. Get some resistors (or car light bulbs if it's 12V as in your example) and see how many it will power before it won't start into the load. That will give you an idea.
In my experience, nothing that says "300W" ever uses 300W. With the minimal information you've given, I would guess you have about 100W of useful DC power, maybe more but without testing you won't know. Why not call Bose and ask them? They will probably laugh at you but they might help you out.