Switching Power Supplies in AV Receivers

[Verdinut]

Most AV Receiver manufacturers don't explain in detail what replaced the standard power supplies with massive transformers which represented most of the weight of the products several years ago.

Were those heavy power supplies all replaced by the more efficient, light and cooler-running switching power modules? This is what I believe is the case with the Marantz SR5010 receiver that I use.


Also, I noticed that, as compared to my previous NAD Flagship T763, the Marantz seems to put out a wider dynamic range. Yesterday, I was listening to an amazing performance of Beethoven's 4th symphony, from a 1967 recording with the Vienna Philharmonic under Hans Schmidt-Isserstedt. There wasn't the compression that I felt with the NAD amplifiers.


That more impressive dynamism most likely has to do with the more ample current to the audio power circuitry by changing the supply rails at least 100,000 times per second through a low impedance circuit.



Someone has any comments?

 

[TLS Guy]

I have a severe dislike of switching power supplies for power amps. They are complicated, and virtually impossible to fix. They are significantly more unreliable than conventional power supplies in power amps. Over the years there has been a tendency, especially in Far Eastern gear, to make power supplies needlessly complicated.

There is evidence that simpler old fashioned designs make for better sounding power amps.

The next issue is that switching supplies do have an advantage when powering computer type equipment which exists in spades in the modern receiver. However compared to power amps the power demands are far less and the load much more stable.

This is another really good reason to not use receivers. As I have said before, I would never use a receiver in anything but a low budget system. I would never use one in a reference system. As time goes by a receiver makes less and less sense, and they never made much to start with.

 

[Speedskater]

When it's comes to SMPS's there are the good the bad and the ugly. In the distant past they were all bad. But now there is great demand for better, smaller or cheaper supplies. In a receiver a good SMPS is better than a linear supply can hope to be. Engineers like Bruno Putzeys have advanced the designs.

 

[PENG]

Were those heavy power supplies all replaced by the more efficient, light and cooler-running switching power modules? This is what I believe is the case with the Marantz SR5010 receiver that I use.

I don't believe the SR5010 or even the top model SR7011 use switching power modules, assuming you meant SMPS, or switch rails design such as in class G and H. At least I see no indication of the SR5010 using such design in Marantz published literature. If they do use such designs, we would have read about it in reviews such as those done by AH, S&V and others.

Also, I noticed that, as compared to my previous NAD Flagship T763, the Marantz seems to put out a wider dynamic range. Yesterday, I was listening to an amazing performance of Beethoven's 4th symphony, from a 1967 recording with the Vienna Philharmonic under Hanz Schmidt-Isserstedt. There wasn't the compression that I felt with the NAD amplifiers.

Was that an apple to apple comparison, which NAD amp did you compare the SR5010 with? If both amps have the same rated continuous output, the NAD should do better in short burst kind of dynamic (such as the IHF's 20 ms).

That more impressive dynamism most likely has to do with the more ample current to the audio power circuitry by changing the supply rails at least 100,000 times per second through a low impedance circuit.

I don't know why you would jump to such conclusion. There are more than one way to deliver high dynamic power efficiently, switching power supply rail voltage is just one way. For example, you already know many class D amplifiers such as those by QSC and Crown Audio can provide very high power output into low impedance, without using the switching rail voltage technology.

 

[PENG]

When it's comes to SMPS's there are the good the bad and the ugly. In the distant past they were all bad. But now there is great demand for better, smaller or cheaper supplies. In a receiver a good SMPS is better than a linear supply can hope to be. Engineers like Bruno Putzeys have advanced the designs.

I agree with your comment on SMPS, but do you really believe the OP's SR5010 use the SMPS design, or even switching rails he mentioned? Sorry, I just don't..

 

[highfigh]

If anyone wants to know why the manufacturers have changed most models to SMPS, it's because of shipping costs. They can hit more of their price points with a lighter box and for most people, the result is good enough. For the upper models, which will be purchased by people who are/think they are more discerning, they use a transformer. In the pro market, where most of the amplifiers will be used in a place where the ultimate sound quality can't be heard anyway, it's still a matter of moving the products from one place to another. Trucking a tour rig charges are partially determined by weight and when they knock off hundreds of pounds from their amplifier racks, they save money even if they aren't moving fewer items. Smaller and lighter is different it allows them to move more items, as well.

 

[Verdinut]

I don't believe the SR5010 or even the top model SR7011 use switching power modules, assuming you meant SMPS, or switch rails design such as in class G and H. At least I see no indication of the SR5010 using such design in Marantz published literature. If they do use such designs, we would have read about it in reviews such as those done by AH, S&V and others.



Was that an apple to apple comparison, which NAD amp did you compare the SR5010 with? If both amps have the same rated continuous output, the NAD should do better in short burst kind of dynamic (such as the IHF's 20 ms).



I don't know why you would jump to such conclusion. There are more than one way to deliver high dynamic power efficiently, switching power supply rail voltage is just one way. For example, you already know many class D amplifiers such as those by QSC and Crown Audio can provide very high power output into low impedance, without using the switching rail voltage technology.

The NAD had the same rated continuous output of 100 watts/ch but, as far as I can tell, it didn't have the bass punch which the SR5010 has.

How would you explain then the important reduction in weight if the receivers still use the conventional power supplies. To my knowledge, the standard power supply requires a massive transformer to provide the necessary current at 50 or 60 Hz to drive high wattage outputs. So, how would they manage to use smaller transformers to deliver high dynamic power with a conventional power supply?

By the way, QSC have been manufacturing their DCA (Digital Cinema Amplifier) line which use the SMPS technology, with either Class AB or 2-tier Class H output circuitry depending on maximum power output. They have been used in many theatres for several years. If they had not been reliable, I am sure they would have been removed from cinemas.

In the Montreal area, we have 6 Cineplex theatres fully equipped with QSC sound systems. I had the opportunity to watch several Met Opera direct satellite broadcasts in two of those theatres and they perform pretty well.

 

[Verdinut]

If anyone wants to know why the manufacturers have changed most models to SMPS, it's because of shipping costs. They can hit more of their price points with a lighter box and for most people, the result is good enough. For the upper models, which will be purchased by people who are/think they are more discerning, they use a transformer. In the pro market, where most of the amplifiers will be used in a place where the ultimate sound quality can't be heard anyway, it's still a matter of moving the products from one place to another. Trucking a tour rig charges are partially determined by weight and when they knock off hundreds of pounds from their amplifier racks, they save money even if they aren't moving fewer items. Smaller and lighter is different it allows them to move more items, as well.

Some pro audio amplifiers are used in recording studios and some are also used, as you know, in theatres. For example, QSC Audio manufacture several lines of amplifiers with the SMPS technology among which is their DCA (Digital Cinema Amplifier) line. So, those DCA amps wouldn't have a sound quality that matches that of many audiophile amplifiers?

 

[PENG]

The NAD had the same rated continuous output of 100 watts/ch but, as far as I can tell, it didn't have the bass punch which the SR5010 has.

I have no idea why you are experiencing that. My little NAD amp has no such issues when compared to my much bigger amps as long as I don't push it beyond it's limit.

How would you explain then the important reduction in weight if the receivers still use the conventional power supplies. To my knowledge, the standard power supply requires a massive transformer to provide the necessary current at 50 or 60 Hz to drive high wattage outputs. So, how would they manage to use smaller transformers to deliver high dynamic power with a conventional power supply?

I can see that the newer Marantz AVRs, say compared to the older models such as the SR5003, 5004, 6003,6004 and 7002, seemed to have gone on diet. The chassis appear to be flimsier, and not all metal either. They also now have fans now, so probably have less and lighter heat sinks too. The transformers still seem quite large, too large to be found in typical amps based on switching mode power supplies rated at the 100WPC range anyway. In fact, the transformers don't look smaller than those found in their predecessors, so perhaps D&M has managed to custom design them to have equal or better power capability with lighter cores. If you look at their power consumption figures, the SR5010 and SR5011 are specified at 650W, that's almost 10% higher than that of the 6 lbs heavier SR5003. That's another thing, amps that use SMPS typically won't show such relatively high power consumption figures.

By the way, QSC have been manufacturing their DCA (Digital Cinema Amplifier) line which use the SMPS technology, with either Class AB or 2-tier Class H output circuitry depending on maximum power output. They have been used in many theatres for several years. If they had not been reliable, I am sure they would have been removed from cinemas.

I believe well designed/build SMPS or the class G/H rail voltage switching type of power supplies are fine so you don't need to convince me, but feel free to try and convince TLS Guy, who I don't always agree with. IMHO, like most things, we should not generalize and say one design is good and the other is bad. There are usually pros and cons for each design.

The bottom line is, I still don't believe your SR5010 uses the SMPS. I also don't think Marantz AVRs use switching power rail voltages (the so called class G and class H) yet either. On the contrary, NAD does use a higher voltage rail in their so called "PowerDrive" feature, though apparently not of the multiple or continuously modulated type, but just one higher voltage rail. You can read more about their "Powerdrive" thing in the link below.

https://support.nadelectronics.com/hc/en-us/articles/201906277-NAD-Full-Disclosure-Power

Just for clarity, switching mode power supply (SMPS) and the class G and H's voltage rails switching or modulating are different things, that can be used together, but not always.

http://www.audioholics.com/audio-amplifier/amplifier-classes

 

[Verdinut]

I have no idea why you are experiencing that. My little NAD amp has no such issues when compared to my much bigger amps as long as I don't push it beyond it's limit.



I can see that the newer Marantz AVRs, say compared to the older models such as the SR5003, 5004, 6003,6004 and 7002, seemed to have gone on diet. The chassis appear to be flimsier, and not all metal either. They also now have fans now, so probably have less and lighter heat sinks too. The transformers still seem quite large, too large to be found in typical amps based on switching mode power supplies rated at the 100WPC range anyway. In fact, the transformers don't look smaller than those found in their predecessors, so perhaps D&M has managed to custom design them to have equal or better power capability with lighter cores. If you look at their power consumption figures, the SR5010 and SR5011 are specified at 650W, that's almost 10% higher than that of the 6 lbs heavier SR5003. That's another thing, amps that use SMPS typically won't show such relatively high power consumption figures.



I believe well designed/build SMPS or the class G/H rail voltage switching type of power supplies are fine so you don't need to convince me, but feel free to try and convince TLS Guy, who I don't always agree with. IMHO, like most things, we should not generalize and say one design is good and the other is bad. There are usually pros and cons for each design.

The bottom line is, I still don't believe your SR5010 uses the SMPS. I also don't think Marantz AVRs use switching power rail voltages (the so called class G and class H) yet either. On the contrary, NAD does use a higher voltage rail in their so called "PowerDrive" feature, though apparently not of the multiple or continuously modulated type, but just one higher voltage rail. You can read more about their "Powerdrive" thing in the link below.

https://support.nadelectronics.com/hc/en-us/articles/201906277-NAD-Full-Disclosure-Power

Just for clarity, switching mode power supply (SMPS) and the class G and H's voltage rails switching or modulating are different things, that can be used together, but not always.

http://www.audioholics.com/audio-amplifier/amplifier-classes

I know that SMPS and output stage driving switching rail voltages are two different things.
For instance, QSC use both techniques in their Class H DCA2422, 3022 and 3422 amps for their high outputs, from 700 to 1100 watts/ch at 4 ohms with both channels driven.

Maybe Marantz use as NAD do a higher voltage rail in their amp circuits.
Friday, I wrote to Marantz because I'm having an updating problem. I took the opportunity to ask them about the power supply, but I don't think as you were mentioning a while ago, that I will get more info unless I insist and speak with someone at a higher level.

 

[PENG]

I know that SMPS and output stage driving switching rail voltages are two different things.
For instance, QSC use both techniques in their Class H DCA2422, 3022 and 3422 amps for their high outputs, from 700 to 1100 watts/ch at 4 ohms with both channels driven.
Maybe Marantz use as NAD do a higher voltage rail in their amp circuits.
Friday, I wrote to Marantz because I'm having an updating problem. I took the opportunity to ask them about the power supply, but I don't think as you were mentioning a while ago, that I will get more info unless I insist and speak with someone at a higher level.

Yes, for such technical topic on SMPS, Class G, H power supply topology, you are going to need to talk to their level 2 (if exist) or higher in order to get a real answer. Or you can take my word for it, that they are not using SMPS and/or class G/H to help reduce weight. I suppose eventually they may, or will, for all the good reasons, but not yet.

Have you ordered your QSC amps yet?

 

[Verdinut]

I have no idea why you are experiencing that. My little NAD amp has no such issues when compared to my much bigger amps as long as I don't push it beyond it's limit.



I can see that the newer Marantz AVRs, say compared to the older models such as the SR5003, 5004, 6003,6004 and 7002, seemed to have gone on diet. The chassis appear to be flimsier, and not all metal either. They also now have fans now, so probably have less and lighter heat sinks too. The transformers still seem quite large, too large to be found in typical amps based on switching mode power supplies rated at the 100WPC range anyway. In fact, the transformers don't look smaller than those found in their predecessors, so perhaps D&M has managed to custom design them to have equal or better power capability with lighter cores. If you look at their power consumption figures, the SR5010 and SR5011 are specified at 650W, that's almost 10% higher than that of the 6 lbs heavier SR5003. That's another thing, amps that use SMPS typically won't show such relatively high power consumption figures.



I believe well designed/build SMPS or the class G/H rail voltage switching type of power supplies are fine so you don't need to convince me, but feel free to try and convince TLS Guy, who I don't always agree with. IMHO, like most things, we should not generalize and say one design is good and the other is bad. There are usually pros and cons for each design.

The bottom line is, I still don't believe your SR5010 uses the SMPS. I also don't think Marantz AVRs use switching power rail voltages (the so called class G and class H) yet either. On the contrary, NAD does use a higher voltage rail in their so called "PowerDrive" feature, though apparently not of the multiple or continuously modulated type, but just one higher voltage rail. You can read more about their "Powerdrive" thing in the link below.

https://support.nadelectronics.com/hc/en-us/articles/201906277-NAD-Full-Disclosure-Power

Just for clarity, switching mode power supply (SMPS) and the class G and H's voltage rails switching or modulating are different things, that can be used together, but not always.

http://www.audioholics.com/audio-amplifier/amplifier-classes

I remember using the "Soft Clipping" feature on the NAD. I understand that this feature was reducing the amps power output and removing its headroom, I believe that could explain the situation.

Your comments are always welcome.

 

[Verdinut]

Yes, for such technical topic on SMPS, Class G, H power supply topology, you are going to need to talk to their level 2 (if exist) or higher in order to get a real answer. Or you can take my word for it, that they are not using SMPS and/or class G/H to help reduce weight. I suppose eventually they may, or will, for all the good reasons, but not yet.

Have you ordered your QSC amps yet?

I haven't ordered them yet. As I was mentioning in a previous post, the DCA 1222s cost almost twice the price of the RMX 850a's. I can't afford to buy the three in one shot, but I expect to purchase one within one month or so, and the other two next Winter.
One interesting feature of the DCA 1222, is that each channel will drive four 8 ohm speakers in parallel as it can handle an impedance of 1.6 ohms.

One of my friends has some Classé amps and I suggested to him that we eventually compare the amps. That should really be interesting. I don't expect a very noticeable difference between the two. I shall let you know how the experience turned out.

 

[highfigh]

Some pro audio amplifiers are used in recording studios and some are also used, as you know, in theatres. For example, QSC Audio manufacture several lines of amplifiers with the SMPS technology among which is their DCA (Digital Cinema Amplifier) line. So, those DCA amps wouldn't have a sound quality that matches that of many audiophile amplifiers?

Well, it depends- can they still hear as well as they need to, in order to make a decision about an amplifier's sound quality? Do they even have any say in the equipment choices? As much as many people want to believe that all studios are filled with state of the art equipment, they still use Yamaha NS-10 speakers and I have never heard anyone say those sound good. Having listened to them in studios, I have to go along with the opinions about them not sounding good, but they do reveal sonic problems and once those have been dealt with, the result generally sounds good on just about anything.

Theaters? Really? I have heard more bad audio in theaters than I care to. They might use good equipment, but great gear that's set up poorly serves no particular function.

Also, equipment at the higher level needs to live up to some standard, or people will never buy it again. Making bad equipment that's expensive is just a bad idea- it's bound to bite someone on the butt.

 

[lovinthehd]

Well, it depends- can they still hear as well as they need to, in order to make a decision about an amplifier's sound quality? Do they even have any say in the equipment choices? As much as many people want to believe that all studios are filled with state of the art equipment, they still use Yamaha NS-10 speakers and I have never heard anyone say those sound good. Having listened to them in studios, I have to go along with the opinions about them not sounding good, but they do reveal sonic problems and once those have been dealt with, the result generally sounds good on just about anything.

Theaters? Really? I have heard more bad audio in theaters than I care to. They might use good equipment, but great gear that's set up poorly serves no particular function.

Also, equipment at the higher level needs to live up to some standard, or people will never buy it again. Making bad equipment that's expensive is just a bad idea- it's bound to bite someone on the butt.

So your hearing is able to distinguish amp type easily?

 

[PENG]

I remember using the "Soft Clipping" feature on the NAD. I understand that this feature was reducing the amps power output and removing its headroom, I believe that could explain the situation.

Your comments are always welcome.

As soon as I unpacked my little NAD amp, the first thing I checked was the position of that switch. It's default position was "off". If you had that "On", then unless you weren't running your amp any where near it's rated output, you would get the benefits of soft clip alright, but at the expense of losing some dynamic impacts in some music. We all know most Beethoven's symphonies are going to have some major dynamic swings.

 

[highfigh]

So your hearing is able to distinguish amp type easily?

If an amplifier has a sonic characteristic that's specifically due to the power supply, it's possible to hear it. I'd like to do a double-blind comparison but they're hard to come by.

My point is that people in studios are often subjected to excessive SPL, feedback and other things that can and do damage their hearing. If they did live sound, I would say it's guaranteed that their hearing ability is lacking, so I guess the answer to your question may be "No" because I have done live sound but I have also used ear plugs for decades, to prevent further damage. I can still hear high frequencies over 15KHz well and when I do sweeps or test tones, it's not gone. When I had my last hearing test, my hearing acuity was better than average for someone younger than my age.

 

[TLS Guy]

This thread is of real importance to audio enthusiasts, and is cotroversial.

I did not have time to write an extended post yesterday.

However I find that the renowned amplifier designer Douglas Self has written the article for me.

I think it important that you all read this article.

I'm firmly of the opinion that unregulated power supplies are the best option for power amps and I stress power amps.

These are simple and reliable. All the rest are more complex than the amps, and prone to catastrophic failure, that is either difficult to fix and frequently not worth the trouble. To build linear and regulated supplies for power amps is expensive and only high quality caps should be used. If not the equipment will not be know for longevity. In addition unregulated supplies have the lowest inter channel cross talk. Switching power supplies fall into the same category regarding these issues.

Peng, my Quad power amps have unregulated supplies. This is why they don't quite double their power into a 4 ohm load. They are 150 watts into 8 ohm, but 250 watts into 4 ohms and not 300 watts.

This goes to a big reason why I do not like receivers, and nor did Peter Walker. In fact it was him who really put me off the idea. He never designed a receiver and adamantly refused to do so.

The reason is simple, in that the low voltage gain/processor sections do require regulation. This makes for a source of noise in the case in which the power amps are located.

So it is best the have the low voltage, low power sections in a separate case from the power sections. This is and will always be ideal.

As you know I'm trouble adverse, and desire long life from my equipment. That puts me emphatically in the unregulated power supply camp for power amplifiers.

We just had a case recently of a Yamaha M70 that almost certainly had a bad problem with the massively complex regulated power supply. It had far more components than the amps. In addition the amps were inordinately complicated because of the protection required to try and stop output device failure from frying the hugely complex regulated power supply. That unit was pretty much unfixable except by an exceptional genius!

 

[slipperybidness]

This thread is of real importance to audio enthusiasts, and is cotroversial.

I did not have time to write an extended post yesterday.

However I find that the renowned amplifier designer Douglas Self has written the article for me.

I think it important that you all read this article.

I'm firmly of the opinion that unregulated power supplies are the best option for power amps and I stress power amps.

These are simple and reliable. All the rest are more complex than the amps, and prone to catastrophic failure, that is either difficult to fix and frequently not worth the trouble. To build linear and regulated supplies for power amps is expensive and only high quality caps should be used. If not the equipment will not be know for longevity. In addition unregulated supplies have the lowest inter channel cross talk. Switching power supplies fall into the same category regarding these issues.

Peng, my Quad power amps have unregulated supplies. This is why they don't quite double their power into a 4 ohm load. They are 150 watts into 8 ohm, but 250 watts into 4 ohms and not 300 watts.

This goes to a big reason why I do not like receivers, and nor did Peter Walker. In fact it was him who really put me off the idea. He never designed a receiver and adamantly refused to do so.

The reason is simple, in that the low voltage gain/processor sections do require regulation. This makes for a source of noise in the case in which the power amps are located.

So it is best the have the low voltage, low power sections in a separate case from the power sections. This is and will always be ideal.

As you know I'm trouble adverse, and desire long life from my equipment. That puts me emphatically in the unregulated power supply camp for power amplifiers.

We just had a case recently of a Yamaha M70 that almost certainly had a bad problem with the massively complex regulated power supply. It had far more components than the amps. In addition the amps were inordinately complicated because of the protection required to try and stop output device failure from frying the hugely complex regulated power supply. That unit was pretty much unfixable except by an exceptional genius!

No surprises here. If you read books by G Randy Sloan and/or Bob Cordell, they say the same thing.

 

[lovinthehd]

If an amplifier has a sonic characteristic that's specifically due to the power supply, it's possible to hear it. I'd like to do a double-blind comparison but they're hard to come by.

My point is that people in studios are often subjected to excessive SPL, feedback and other things that can and do damage their hearing. If they did live sound, I would say it's guaranteed that their hearing ability is lacking, so I guess the answer to your question may be "No" because I have done live sound but I have also used ear plugs for decades, to prevent further damage. I can still hear high frequencies over 15KHz well and when I do sweeps or test tones, it's not gone. When I had my last hearing test, my hearing acuity was better than average for someone younger than my age.

So your point was that maybe some operators of theaters/live sound/studio venues might have hearing damage and might pick a poorer amp, not necessarily the type of amp, but just in general. Can you tell the difference between a pro amp and a home consumer amp generally was what I was asking, since that's what you've implied. What are those audible clues attributed to power supply type?