hello, I want to make an amplifier that works on a +-25 power supply and a 1 ohm load.
how many transistors 2SC5200 and 2SA1943 do I need to work for a long time without problems
Thanks !
how many transistors 2SC5200 and 2SA1943 do I need to work for a long time without problems
Thanks !
Bridge mode or not? If not that's about 250W required at 16A, bridged 1kW at 31A... The SOA for 2SC5200 suggests about 5A each for non-bridged operation, 3A each bridged, so 3 pairs for normal, 10 pairs for bridged?
that will be non-bridged amplifier with 8 speakers 8 ohm each , for background sound at pub .
according to my calculations it will be 200 watts maximum .
according to my calculations it will be 200 watts maximum .
Mark Tillotson , you look 100 ms SOA curve ?
Well you really need to redraw the curves on a linear-linear plot, and draw load-lines and load-ellipses (for reactive load) to get a more precise answer. And not confuse rms with peak either, which I fear I may have done. If you assume a fully reactive load then the worse case is very roughly the peak voltage at peak current, with a resistive load about 1/2 peak V at 1/2 peak I...
That s 20A output current, so 4 pairs will results in 5A per pair, that should be the minimum required.
Beside the impedance can dip below 1R at some frequencies, so this should be accounted as well.
I wouldnt count on 7A per pair, that s just too much, at 5A the beta is still around 100 and at 7A it collapse
at 70 or so and although that would work it s not optimal for best possible perfs and long term reliability.
Beside the impedance can dip below 1R at some frequencies, so this should be accounted as well.
I wouldnt count on 7A per pair, that s just too much, at 5A the beta is still around 100 and at 7A it collapse
at 70 or so and although that would work it s not optimal for best possible perfs and long term reliability.
Hi
Instead of connecting all 8 speakers in parallel, can you connect them as a series/parallels arrangement? Having 2 speakers in series will give you 16 ohm then 4 groups like this connected in parallel will give you a total load of 4 ohm for all 8 speakers. Much easier to manage vs 1 ohm. Back in the days (35 years ago…) I used to install Dolby sound in theatre and it’s the way we used to hook up speakers for the surround sound.
Have you considered wiring the speakers in series-parallel for a net 4 ohm load?
This is 8 speakers per amplifier channel?
Connect 4 speakers in parallel. Connect this group in series with another group of 4 speakers in parallel.
Total = 4 ohms.
This is 8 speakers per amplifier channel?
Connect 4 speakers in parallel. Connect this group in series with another group of 4 speakers in parallel.
Total = 4 ohms.
Low voltage high current power supplies are harder to work with. More % voltage drop under load, which makes the amp less efficient. Consider a distributed “constant voltage” system. The savings in wire will probably pay for the 8 transformers since you can run lower gauge.
You don’t need to run it all the way to “70 volts” either. It can be run quite nicely at 35 or 50, and you can find an off the shelf amp that will do that at “8 ohms”. You may be able to find “25 volt” transformers, too.
You don’t need to run it all the way to “70 volts” either. It can be run quite nicely at 35 or 50, and you can find an off the shelf amp that will do that at “8 ohms”. You may be able to find “25 volt” transformers, too.
Suggestion: I made hundreds of low cost installations like yours in bars, pubs, background sound in large shops, always connect speakers in series-parallel; it makes it much easier since each branch will stay at 8 ohms.
MUCH easier on wire requirements, amplifier, any 100-200W per channel amp will do.
No big deal on installation since you will use screw terminals on each speaker, somebody must pass wires through conduit anyway, climb stairs to mount them on wall or ceiling, etc.
It makes your whole job much easier, including building/sourcing the amp.
MUCH easier on wire requirements, amplifier, any 100-200W per channel amp will do.
No big deal on installation since you will use screw terminals on each speaker, somebody must pass wires through conduit anyway, climb stairs to mount them on wall or ceiling, etc.
It makes your whole job much easier, including building/sourcing the amp.
@desislavov
Music playback for PA venues that is going to burn away tons of kWh every year I would consider a Class D amplifier, in most cases there is no need for high fidelity audio reproduction in a noisy pub environment, Class D generates much less heat and saves on the electricity bill due to its much higher efficiency.
edit: btw, going the DIY way is fun but you have to think of the legal matters too in case your amp somehow malfunctions and maybe causing a fire and/or harm to the customers etc., better buying a ready made Class D amp that has its electrical safety approval in order, it helps in case the insurance company is involved and other legal issues occurs.
Music playback for PA venues that is going to burn away tons of kWh every year I would consider a Class D amplifier, in most cases there is no need for high fidelity audio reproduction in a noisy pub environment, Class D generates much less heat and saves on the electricity bill due to its much higher efficiency.
edit: btw, going the DIY way is fun but you have to think of the legal matters too in case your amp somehow malfunctions and maybe causing a fire and/or harm to the customers etc., better buying a ready made Class D amp that has its electrical safety approval in order, it helps in case the insurance company is involved and other legal issues occurs.
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Concider using a car amp made for sub 1 Ohm load. Some are happy playing at 0.5 Ohm. Will be cheaper than all the transistors and heat sinks you have to buy. Use a 12V SMPS to power it, with the adjuster to max voltage, 14.4V typically.
Not to mention reliable and no problems with insurance claims.
Not to mention reliable and no problems with insurance claims.
Car sub for 1 ohm might not play 2 kHZ properly.
With anything that is not approved for the purpose you may end up with insurance hassles. If you use class 2 wiring, it’s pretty much got to say “class 2 wiring may be used”. Which means it will limit itself properly in the event of a short, and nominally will not put out more than 30 V RMS. Peaks may go to 70 (as in CV PA systems). Off the shelf PA amps (like old QSC) are suitable for doing either CV 70 volt or the series-parallel would be cheap and insurance-friendly.
And yes, power savings from class D can be substantial, but that won’t be cheap. The car amp idea may not work well and still might be an insurance hassle not because of safety but because of using something not for its designated purpose. That’s still considered a risk. I ended up with a pair of 200 W per channel 70V class D amps buying a lot from some conference rooms that were being renovated. I gutted the telephone interfaces for the cases and SMPS’s, and kept the two Extron PA amps. They are nice. I’d hate to even ASK what they cost new - but one would be perfect for this.
With anything that is not approved for the purpose you may end up with insurance hassles. If you use class 2 wiring, it’s pretty much got to say “class 2 wiring may be used”. Which means it will limit itself properly in the event of a short, and nominally will not put out more than 30 V RMS. Peaks may go to 70 (as in CV PA systems). Off the shelf PA amps (like old QSC) are suitable for doing either CV 70 volt or the series-parallel would be cheap and insurance-friendly.
And yes, power savings from class D can be substantial, but that won’t be cheap. The car amp idea may not work well and still might be an insurance hassle not because of safety but because of using something not for its designated purpose. That’s still considered a risk. I ended up with a pair of 200 W per channel 70V class D amps buying a lot from some conference rooms that were being renovated. I gutted the telephone interfaces for the cases and SMPS’s, and kept the two Extron PA amps. They are nice. I’d hate to even ASK what they cost new - but one would be perfect for this.