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The Truth About HiFi Amplifier Power Supplies

egellings

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I remember that those Sola V-regulating transformers got really hot in operation.
 

egellings

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That is correct. The output waveform is severely distorted and flat topped. The flat-topping is largely responsible for the heating.
 

atmasphere

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That is correct. The output waveform is severely distorted and flat topped. The flat-topping is largely responsible for the heating.
Right. And also an indication of harmonics, some of which can mess with power transformers (5th harmonic) and the like. This is a reason that ferro-resonant regulating transformers can be a source of noise in audio systems.
 

Joe852

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I'm curious if an amplifier was designed with batteries in parallel with the power supply could it have a ton more instantaneous current? Certain types of batteries can dump a ton of current it seems like it would make a lot of sense. If you could get super high current in a 100wpc amp I'd think hardly anyone would need any more.
 

egellings

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I think that the reservoir capacitors in a power supply already do a good job of that, and they can have a much lower series resistance than batteries do, especially when partially discharged. Basically, it's a solved problem.
 

Joe852

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I've gone from a single stereo amp to a pair of bridged mono-blocks twice and both times I thought having what would appear to be overkill made a significant difference in low-end grunt. The amps I'm running now can dump around 800 watts into my Thiel 3.7s, which is absurd, I never get anywhere near that volume and they'd burn up immediately long before I got there. I don't know, it's one of those subjective impressions that I can't prove but I didn't want to spend more money. I hate spending money. I felt like the single amp that according to spec put out 350 watts into 4 ohms sounded weak. I went back to the dealer and bought the demo model of the amp I had and ran them bridged mono. I never felt like there was anything missing again. I had gotten the exact same impression years earlier when I went from 1 to 2 amps in a completely different system.
 

Doodski

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I've gone from a single stereo amp to a pair of bridged mono-blocks twice and both times I thought having what would appear to be overkill made a significant difference in low-end grunt. The amps I'm running now can dump around 800 watts into my Thiel 3.7s, which is absurd, I never get anywhere near that volume and they'd burn up immediately long before I got there. I don't know, it's one of those subjective impressions that I can't prove but I didn't want to spend more money. I hate spending money. I felt like the single amp that according to spec put out 350 watts into 4 ohms sounded weak. I went back to the dealer and bought the demo model of the amp I had and ran them bridged mono. I never felt like there was anything missing again. I had gotten the exact same impression years earlier when I went from 1 to 2 amps in a completely different system.
What power amps have you bridged most recently? :D
 

Joe852

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Currently Cambridge 840s from around 2010. Previously Classe CA200s from 1996.
 

Angsty

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I had thought about moving from a single Bryston 4B-ST to a pair of monoblock 7B-STs for my Thiel CS6s. But after I got the 4B-ST re-capped with larger capacitors, I had no more worries. The fact that the capacitors were new versus 10% larger was probably the bigger factor.

Finding the space for another 50 lb. chassis was going to be a spousal issue, as well. :D
 

sq225917

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The thing about bridging an amp.is it halves its ability to drive low impedance loads, so in the case of vicious speakers, particularly ported ones with an impedance peak below sat 4 ohms in the bass, what you are actually getting is floppy bass, not more accurate bass.

Check the impedance plot of your speakers, it'll indicate what the likelihood is...
 

Philbo King

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The present state of the art in DC power supplies consists of:
Power factor correction->SMPS, but I have no idea if currently built consumer (non-pro) audio gear uses it.

Much of the pro gear does, especially in high power applications such as PAs.

Off topic: The amplifiers, by the way, are class D or better for currently built products (excluding guitar & bass amps where tubes still rule). Class A, AB and B amps are simply too inefficient, heavy and costly to use for pro work.
 
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Honu

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Hi all,
I'm living off grid, i find it pretty inefficient to convert DC (batteries/PV) to AC for it to be convert back to DC in my amplifier.
Why are there no amplifier with external power supplies, i do not know what kind of internal voltage amplifiers are using, but i can easily provide 12V, 24V, 36V or 48V from my batteries.
I ordered a Fosi Audio class D cheap amplifier cause it's the only one i could find ... working directly on 36V. (one TB10D and one BT30D Pro)
But my question, is more .. why are there not more amplifier with external swappable power sources ?
 
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Doodski

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i can easily provide 12V, 24V, 36V or 48V from my batteries.
You will need positive and negative voltage supplies to power a audio amplifier. The positive voltage will make the speaker driver go out and the negative voltage will pull it in. So it can go in and out and make sound. The Fosi is a outlier design and is very suited for your needs. External swappable power supplies are not common because people want them all in one.
 

Honu

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You will need positive and negative voltage supplies to power a audio amplifier. The positive voltage will make the speaker driver go out and the negative voltage will pull it in. So it can go in and out and make sound. The Fosi is a outlier design and is very suited for your needs. External swappable power supplies are not common because people want them all in one.
Maybe it's for convenience .. but it's not for me .. ;)
 

Ken Tajalli

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Maybe it's for convenience .. but it's not for me .. ;)
Amp designers need to control all aspects of the operation. If they allow third party power supplies or even DIY ones, then it could impact the sound quality of their beloved design, or worse, blow up, and they get sued!
If you want to risk a DIY job, you need to open your amp up to find out what voltages the amp is working with on the rails. It could be +/- 35V or higher.
Then jury-rig batteries to supply both voltages (the plus and minus). Run it on charged batteries.
Then jury-rig a charging solution to charge the batteries overnight! a bit of a hassle, you might realize, it ain't worth it, unless you really have to.
 

Doodski

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Amp designers need to control all aspects of the operation. If they allow third party power supplies or even DIY ones, then it could impact the sound quality of their beloved design, or worse, blow up, and they get sued!
If you want to risk a DIY job, you need to open your amp up to find out what voltages the amp is working with on the rails. It could be +/- 35V or higher.
Then jury-rig batteries to supply both voltages (the plus and minus). Run it on charged batteries.
Then jury-rig a charging solution to charge the batteries overnight! a bit of a hassle, you might realize, it ain't worth it, unless you really have to.
Unless there was a quasi complimentary amp design that came with a Marantz model. Only one rail voltage. :D
 
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