Hi everyone,
I'm building my first loudspeaker/amplifier situation and have a question about choosing power supplies.
It's going to be a multichannel speaker, kind of like a guitar amp but with six or eight (not sure yet) independent audio channels. The goal is to make a more lively/rich/colorful electronic sound coming from loudspeakers so I can play my own digital sound patches with a keyboard and other midi controllers – with audio output not from a regular stereo PA but from a kind of inverted-surround-sound object on stage.
Anyway!
Because it's rather experimental I wanted to make some prototype first that doesn't have to be super high quality and meticulously designed. Still – of course – I bump into so many questions. I found a very cheap stereo amplifier of which I bought a couple for the multiple channels. It specifies the input voltage as 12v and speaker impedance as 4-16Ω. (Quite the range, right?) But because it doesn't specify the ideal electric current from the power supply, I started wondering what would be the difference.
What would be the difference between using a higher vs. a lower current power supply?
I thought maybe with a 5A / 60W power supply I could make a louder sound, or possibly a more refined/controlled sound – but in testing with different power supplies I can't discover a difference. Maybe the amplifiers are just too cheap for the power supply to make a difference.
I am just wondering: is there a benefit in using (more expensive and also heavier) higher current power supplies, or could I just as well use any (cheaper & lighter) power supply as long as it's 12V ? Maybe even 300mA would be enough?
Bonus question: is the answer to this question also connected to which kind of speakers I choose?
Thank you very much for your thoughts!
I'm building my first loudspeaker/amplifier situation and have a question about choosing power supplies.
It's going to be a multichannel speaker, kind of like a guitar amp but with six or eight (not sure yet) independent audio channels. The goal is to make a more lively/rich/colorful electronic sound coming from loudspeakers so I can play my own digital sound patches with a keyboard and other midi controllers – with audio output not from a regular stereo PA but from a kind of inverted-surround-sound object on stage.
Anyway!
Because it's rather experimental I wanted to make some prototype first that doesn't have to be super high quality and meticulously designed. Still – of course – I bump into so many questions. I found a very cheap stereo amplifier of which I bought a couple for the multiple channels. It specifies the input voltage as 12v and speaker impedance as 4-16Ω. (Quite the range, right?) But because it doesn't specify the ideal electric current from the power supply, I started wondering what would be the difference.
What would be the difference between using a higher vs. a lower current power supply?
I thought maybe with a 5A / 60W power supply I could make a louder sound, or possibly a more refined/controlled sound – but in testing with different power supplies I can't discover a difference. Maybe the amplifiers are just too cheap for the power supply to make a difference.
I am just wondering: is there a benefit in using (more expensive and also heavier) higher current power supplies, or could I just as well use any (cheaper & lighter) power supply as long as it's 12V ? Maybe even 300mA would be enough?
Bonus question: is the answer to this question also connected to which kind of speakers I choose?
Thank you very much for your thoughts!
The (maximum) current the amp will draw will depend on the power output (Wattage)
So you need to provide more details, you could put a 12V 3000A supply on it and it will only draw as much as it needs at the time.
Depending on the amp topology it might only draw 100mA when producing no audio, but as soon as you want to listen to it at any volume, it will draw current as required.
Hi Mike, thank you for your thoughts!
Which details should I provide? I'm afraid I don't know anything about the amp topology.
My experience has been that whether I use a 5A power supply or a 300mA one with this amplifier (turning up the volume of the amp all the way): it doesn't seem to make a difference in sound quality or volume. So I'm tempted to just use cheaper/lighter power supplies. Does that make sense?
Which details should I provide? I'm afraid I don't know anything about the amp topology.
My experience has been that whether I use a 5A power supply or a 300mA one with this amplifier (turning up the volume of the amp all the way): it doesn't seem to make a difference in sound quality or volume. So I'm tempted to just use cheaper/lighter power supplies. Does that make sense?
As I've said the current draw will vary in line with the music and the volume you've dialled in..
If the PSU doesn't have a high current capability the supply voltage to the amp will drop in sympathy... simply because it can't hold it up at that current draw, and that isn't good it leads to distortion and the potential for damage.
Without a power output rating you need to disconnect plus or neg to the amp and fit a multimeter in between (in 10A current mode - most meters will have a 10A range and the probes need plugging into to different sockets on the meter for current mode).
Then turn on and monitor what the meter says as you turn the volume up , it will jump about but you should be able to spot a ball park range and peak of current.
Then buy a 12v PSU that at least meets that of exceeds with a good 20% margin.
If the PSU doesn't have a high current capability the supply voltage to the amp will drop in sympathy... simply because it can't hold it up at that current draw, and that isn't good it leads to distortion and the potential for damage.
Without a power output rating you need to disconnect plus or neg to the amp and fit a multimeter in between (in 10A current mode - most meters will have a 10A range and the probes need plugging into to different sockets on the meter for current mode).
Then turn on and monitor what the meter says as you turn the volume up , it will jump about but you should be able to spot a ball park range and peak of current.
Then buy a 12v PSU that at least meets that of exceeds with a good 20% margin.
Tell us what circuit, and voltage.
How many channels?
That should give us some clarity as to what is needed.
How many channels?
That should give us some clarity as to what is needed.
Power supply design is both dirt simple, and very complex *at the same time*. You can directly calculate the *peak* current required from the power supply voltage and load impedance but that is the limit of what you can obtain easily. Anything else requires guesswork, statistics, or measurements because the average current drawn depends on use conditions and the characteristics of the supply itself. You can always use a supply good for the peak current, but that may result in it being significantly oversized. For such a low power application it may not be that bad a penalty to pay, but when you start looking at 500 watt amps you’re talking about real money. Direct measurement on a DMM is fine, IF you can be certain the power supply will not misbehave when you put out peaks too short to be captured by the meter. THAT depends on whether the supply is regulated or not, and the time constants in the regulator.
So how much peak current do you need? If it’s a “bridge” amplifier (common for 12 volt applications - both sides of the speaker connect to hot leads - NO speaker ground) it can draw 1.5 amps peak on an 8 ohm speaker. If it’s just a standard amp with one side of the speaker grounded, the peak is half of that (with double the peak to average ratio). The average currents are always much lower, even with the volume turned up to distortion.
So how much peak current do you need? If it’s a “bridge” amplifier (common for 12 volt applications - both sides of the speaker connect to hot leads - NO speaker ground) it can draw 1.5 amps peak on an 8 ohm speaker. If it’s just a standard amp with one side of the speaker grounded, the peak is half of that (with double the peak to average ratio). The average currents are always much lower, even with the volume turned up to distortion.
I have a meter like that but I wouldn't know how to disconnect plus or neg to the amp. It's just a regular plug, one of those tube-like connections with + on the inside and - on the outside, or vice versa. So I think I have to trial and error this one.
The circuit is like this: 8 channels of audio coming from an external sound card connected to a laptop. These eight channels of audio are spread over four small stereo amplifiers. Each stereo amplifier is connected to a set of speakers of a different type, so from the computer I can send out different signals to different speakers with different sound colors. As a kind of small "speaker orchestra" let's say (or "speaker ensemble"). The amplifier's outputs have the note 4-16Ω, and the amplifier's power input socket has the note 12V. That's it, that's all I know.
Then I thought like this: if I get power supplies with higher currents I could power speakers with higher wattages. So I got 5A power supplies that can deliver 12*5= 60W of power, thinking that now I can attach a speaker with rms 30W for both channels of the stereo amp, totalling in 60W.
Does that make sense?
That's exactly what I'm trying to avoid and why I'm asking how to handle the situation.
This part is very interesting for me, thank you for this information! I don't completely understand: is bridging a wiring technique used for mono summing, or also something that happens inside the schematics of a stereo (or more-than-two-multi-channel) amplifier? Is there a way to figure out whether my stereo amp is a bridge amplifier or not? I would assume it's a standard amp with both plus and minus but that's just because I never would think to connect a speaker two to different plus sides. If I understand you correctly: a normal 12V amplifier can draw 0.75 A peak on an 8 Ω speaker, right? So I would need a 1.5A / 18V power supply for one stereo amplifier. And for 4Ω speakers it would be double that. Do I understand you correctly?
I'm sorry if I'm oblivious to something! I appreciate all your responses very much, so thank you.
What precisely is "a normal amp" ??? 🙄
We need the power output in watts
In the absence of the spec of this amp, if you break into the power connection (on either the pos or neg) and put your multimeter (set to current range) it will tell you all you need to know about how much current your "normal amp" is drawing. - end of story.
12V bridged amp into 8 ohms can peak 2A or more, as "8 ohm" nominal speakers are usually 5 to 6 ohms resistive, and in bridged mode you get the full 12V to play with rather than +/-6V