Does transfomer is symbol of richness in Amplifiers? what about SMPS

[Audio_Freek]

Hello Fm's

Now a days am getting more into the Sound reproduction methodologies often and part of my recent thought was about Usage of transformers in amplifiers.

SMPS is one of the best resolution to power the Electronic equipments seamless , But i cant see only the low end (Local Made )amplifiers or the Home theaters uses SMPS for the power manage units.

I got to know that SMPS can give almost 100% Humming free Music and its very cheap too + can be easily rectified during any issues.

So why does the Transformers are still ruling the Amplifier area in power unit. As the SMPS have very high advantage than transformer, and not be put under research so that the even better power management can be on cards with very low weight.

 

[kanwar]

Hello Fm's

Now a days am getting more into the Sound reproduction methodologies often and part of my recent thought was about Usage of transformers in amplifiers.

SMPS is one of the best resolution to power the Electronic equipments seamless , But i cant see only the low end (Local Made )amplifiers or the Home theaters uses SMPS for the power manage units.

I got to know that SMPS can give almost 100% Humming free Music and its very cheap too + can be easily rectified during any issues.

So why does the Transformers are still ruling the Amplifier area in power unit. As the SMPS have very high advantage than transformer, and not be put under research so that the even better power management can be on cards with very low weight.

Some thoughts:

1. Pre-conceived notions that heavier the better are still deep routed in minds of people, SMPS being lighter in weight fails here.

2. An average audio designer cannot design SMPS, learning curve is very steep in order to reach that level. Only few have mastered this.

3. Bad designers making noisy EMI inferno SMPS which gave rise to bad repute for SMPS in the minds of people, hence they stay away from it.

 

[doors666]

Also, I think a transformer can handle transients much better than an smps for the same ratings.

 

[kanwar]

Also, I think a transformer can handle transients much better than an smps for the same ratings.

Only if the SMPS is not designed properly, if SMPS is designed properly to handle peak current demand, then SMPS is better.

 

[Audio_Freek]

Only if the SMPS is not designed properly, if SMPS is designed properly to handle peak current demand, then SMPS is better.

Kanwar,
You have exactly got my point.Just leave about the Entry level and Even Mid priced amplifiers.

Consider the Classe or accuphase which could be considered to be Hi end(For Me)

They are mostly sold 1k$ and above for the basic Models, But even they use the Transformers and not SMPS, So does this means they spend tons of $ for R&d for design and processing and they dont have skilled designer to design a SMPS board? SMPS board can be designed even a layman level, so enriching them for such a big audio gaints should not be an issue.

But i think everybody would accept that Technology Improvement means ovecoming the previous techn and adding more and advance features to that.

Transistors and resisters and now labled into small IC and its has been taken to business as well. So why the Transformers are still getting carried? though an advance SMPS is already in place and not getting room to grow in Amplifier Marker?

 

[Rupam]

The main reasons are interference. SMPS are more prone to Electro Magnetic Interference than transformers.
Read here in depth > http://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCsQFjAA&url=http%3A%2F%2Fwww.iaesjournal.com%2Fonline%2Findex.php%2FIJPEDS%2Farticle%2Fdownload%2F789%2Fpdf&ei=7nxjUqXZPMeUrAfs64A4&usg=AFQjCNHfRNhkARq1rZvFZU1TK4BJJjb1Bw&sig2=kcH7pZ7t2nmgHaJEte6now&bvm=bv.54934254,d.bmk

A manufacturer needs to take account of many schematic design points before implementing them in a AVR, whereas the transformer doen not cause such a concern.

 

[hydrovac]

Hello Fm's

Now a days am getting more into the Sound reproduction methodologies often and part of my recent thought was about Usage of transformers in amplifiers.

SMPS is one of the best resolution to power the Electronic equipments seamless , But i cant see only the low end (Local Made )amplifiers or the Home theaters uses SMPS for the power manage units.

I got to know that SMPS can give almost 100% Humming free Music and its very cheap too + can be easily rectified during any issues.

So why does the Transformers are still ruling the Amplifier area in power unit. As the SMPS have very high advantage than transformer, and not be put under research so that the even better power management can be on cards with very low weight.

It is totally wrong that most audio circuits are powered with large and heavy transformers. Some old ones and some audiophool! ones, but those are a small minority.
SMPS can and are used for audio circuits! can use them from sensitive microphone preamps to huge power amplifiers. In fact, for the larger power amplifiers they are mandatory. Once an amplifier gets over a couple of hundred watts then the power supply needs to be super efficient. Imagine the heat produced by a 1000 watt amp if it's power supply was only 50% efficient!

But even on a smaller scale, the efficiency of a SMPS often makes a lot of sense. If the analog circuitry is properly designed then the noise from the power supply gets rejected by the analog circuitry and doesn't impact the audio noise (very much).

But one thing to keep in mind... A SMPS for audio applications needs to be designed with audio in mind. Of course you'll need better filtering on the output. But you will also need to keep other details in mind. Normally a SMPS will switch at a fixed frequency, but in one of these modes the switching will become somewhat erratic. That erratic behavior might push the output noise into the audio frequency band where it becomes more difficult to filter out. In some cases, you can't control it. In that case you have no choice but to use a different chip or use a hybrid approach.

Some people advocate using only linear power supplies for audio. While linear supplies are less noisy, they have lots of other issues. Heat, efficiency, and weight being the biggest ones. In my opinion, most of the people who preach linear supplies only are either misinformed or lazy. Misinformed because they don't know how to handle switching supplies or lazy because they don't care to learn how to design robust circuits.

 

[kanwar]

Kanwar,
You have exactly got my point.Just leave about the Entry level and Even Mid priced amplifiers.

Consider the Classe or accuphase which could be considered to be Hi end(For Me)

They are mostly sold 1k$ and above for the basic Models, But even they use the Transformers and not SMPS, So does this means they spend tons of $ for R&d for design and processing and they dont have skilled designer to design a SMPS board? SMPS board can be designed even a layman level, so enriching them for such a big audio gaints should not be an issue.

I tend to disagree here,

Costly products in NOWAY suggests that the company invests heavily in INNOVATIVE R&D. There are many costly products than Accuphase and still they are many times inferior technically from it.

Some companies like outsourcing technology, some don't. Designing SMPS is not like designing an audio circuitry.

Again i will disagree that making an Audio SMPS is easy for a layman. No its not the case at all.
Because designing a proper Audio SMPS with Power Factor Correction itself makes its mandatory to have some high-tech testing equipments in order to ensure the working of SMPS which is not a case involved with designing audio circuitry.

For example, For SMPS some important tools:

Full Floating DSO having 100Mhz+ resolution is the bare minimum required tool to carry out waveform level measurements in high voltage circuitry.

You need High Bandwidth Spectrum Analyser which itself is above + 300K INR for carrying out testing on content of harmonic contamination happening in mains. You cannot market the SMPS from layman point of View, have a look at EN61000-3-2-4 directive, which is extremely stringent and meeting it is NOT easy. Then you need a Proper power factor measurement tool + power draw meter which again raises the cost.


Big companies can invest in such tools , no doubt in that,very easy for them when they can invest in Audio analyzers worth 6 lacs +, but a regular Audio designer cannot work on SMPS level unless he attains proper knowledge and experience, its simply different ball game altogether. And as i said high tech costly outsourcing is not easy and not always preferable in audio sector where companies like to have inhouse design expertise.

Having seen INs & Outs of Accuphase at circuit level, i will not say there is any innovation in it, which was not present in electronics field prior to it.

Its just that SMPS is very different than linear electronics, the switching power electronics is very large field and needs lots of expertise and exposure to begin with. Designing an Audio SMPS take much more effort, you have to devise ways for reducing EMI, RFI, noise and many other related factors.

 

[greenhorn]

the main reason I stay away from Class D and SMPS - Please note that this is a personal Opinion - All other things being equal, a linear PSU/Amp is the simpler and has less components than an SMPS/Digital setup and is inherently more reliable. If a class D amp/SMPS fails, then its even more complicated to troubleshoot. the whole thing is usually replaced.

 

[haisaikat]

Sometimes I see that for DACs and other Audio Equipments manufacturers are selling a separately branded liner power supply for better quality of audio. These I have seen costing as much as the original equipment. Will an SMPS based supply be better here or will it be more costly to produce the same? I am certain efficiency may not be the factor here since we are only talking about a couple of watts (50 to 100 max) like those sold for DACs.

 

[Audio_Freek]

Hi Just got through this Link, though there is not or indepth information on the specialty of Transformer, Some information with a basic understanding on Real power of them

Innovative Audio - Interview With Brent Butterworth

 

[kanwar]

Sometimes I see that for DACs and other Audio Equipments manufacturers are selling a separately branded liner power supply for better quality of audio. These I have seen costing as much as the original equipment. Will an SMPS based supply be better here or will it be more costly to produce the same? I am certain efficiency may not be the factor here since we are only talking about a couple of watts (50 to 100 max) like those sold for DACs.

For lower power a dedicated SMPS is not costlier than those fancy linear supplies projected as something exotic by so called high-end manufacturers.

In my personal opinion, i would like to go with a hybrid mix of SMPS + Linear supplies in very high quality audio applications with lower power range [preamps/DACs]. In such case, a linear mains Balanced auto-transformer will be used to step down the mains voltage from 220VAC to somewhat lower value say 24V and then using choice of switching for isolation and linear regulators to do rest of the job. This type has several advantages when the power consumption is less than 100W such as low cost and optimum use of various advanced technologies which are meant for low power by keeping the costs down.

 

[SatMumbai]

Kanwar,

Consider the Classe or accuphase which could be considered to be Hi end(For Me)

I had owned Classe CP-800 which has SMPS power supply and Classe SSP-800 which has a torroidal power supply. CP-800 is a 2 Channel pre-pro where as SSP-800 is multi channel HT pre-pro. I had both at the same time and they were run into same Power Amp (CA-2100) and speakers.

Classe has published a great white paper to 'de'myth SMPS power supply and to me it was convincing.

Coming to the actual experience, CP-800 sounded superb clean with great levels of blackness in silent places of the music. However the SSP-800 was a lot more organic and musical. It was no brainer for me that SSP-800 beats CP-800 even for two channel music.
I am not saying that all this has boiled down to SMPS power supply vs Toroidal but sometimes that sum of the parts is greater than the actual sum.

If it is my money, I would let the SMPS tech mature further and all/most manufacturer use them. Till then I trust the Torroidal transformer to do the duty!
I do not have extensive technical data to support this hypothesis, but based on the extensive equipment I lived with, I come to this conclusion as of now. I am willing to change it, the moment I find a product which does it right the other way.

 

[doors666]

so what are the pros and cons of SMPS. I know these:

Pros:
1. smaller size. Most of the people dont care about this in home audio.
2. Cost. Many people dont care. And its not as if the smps amps are cheaper to purchase.
3. Efficiency. People dont care. They actually aim for tube amps or class A amps at some point of time in life, so efficiency is irrelevant.
4. Regulation. For lower power supplies, even a linear regulated supply gives you that.

Cons:
1. Noise. This scares people. Sure it can be done without noise, but how will one know.
2. Technical complexity. A fault in linear supply is easy to detect and fix. All you need is a dmm. Secondly, a really good designer is needed to do a good smps, Its very difficult for an average person to make sure that his amp has a good smps. For linear, even an idiot can check the caps and trafo ratings etc and do some basic calculations to make sure his supply is good.


Feel free to add more.

 

[captrajesh]

Consider the Classe or accuphase which could be considered to be Hi end(For Me)

They are mostly sold 1k$ and above for the basic Models, But even they use the Transformers and not SMPS, So does this means they spend tons of $ for R&d for design and processing and they dont have skilled designer to design a SMPS board?

That is a valid point.

I tend to disagree here,

Costly products in NOWAY suggests that the company invests heavily in INNOVATIVE R&D. There are many costly products than Accuphase and still they are many times inferior technically from it.

I guess it would be also less expensive to make SMPS than making linear power supply. Also, I can't buy that argument that designing an SMPS is a rocket science that involves some dark science and hence even big companies do not have the wherewithal to design or atleast get designed one for their amp models. If SMPS is equal if not better, why is not everyone using it?

 

[kanwar]

That is a valid point.

I guess it would be also less expensive to make SMPS than making linear power supply. Also, I can't buy that argument that designing an SMPS is a rocket science that involves some dark science and hence even big companies do not have the wherewithal to design or atleast get designed one for their amp models. If SMPS is equal if not better, why is not everyone using it?

Its not a dark science but its a science which is not much popular in audio field, because expertise required in smps is different than what is required in an audio field. There is a considerable difference in the implementation from circuit level, components, pcb layout and testing procedures. Engineers who are expert in Audio field cannot go into smps directly, they need alot to learn and experiment and this is where it is lacking. If you look at non-audio field of smps, you will find its use in Aeronautical and Medical fields and let me tell you , when a SMPS is designed for a medical equipment, its requirement to pass tests of EMI,RFI,ESD,POLR is much more stringent than what you could ever imagine with what is required in Audio. EN61000-3-2-4 & 89/336/EC Electrical Safety 73/23/EC Medical testing ensures you that the smps made for medical field is using state of the art innovations in it.

For a layman like you, it could be difficult to believe that this could be the cause[Because you don't have technical background in order to grasp the difference of level of technical innovation implemented and achieved in smps Vs linear supplies], but given my technical background i have seen and have experienced such things alot. Let alone a PFC stage, i have seen people lacking in basic smps design topologies. They don't even know which topology is best and they will implement audio smps with FLYBACK topology, one example is ICEPOWER modules used in JEFF ROWLAND and BELCANTO, both have SMPS topology which is FLYBACK converter based its one of the worst to be used in audio because of its flawed EMI radiation. And you tell me, why don't these companies HIRE deisgners which can give them topologies based on LLC resonant converters+ CCM PFC as used in some state of art pro-amps/ Pro-mixing desks/ Medical equipments these days?..............

Most of the cost in linear supply goes to the copper windings which are expensive due to rising prices of that metal. In smps the cost is more with high voltage components mainly capacitors and semiconductors.

 

[kanwar]

so what are the pros and cons of SMPS. I know these:

Pros:
1. smaller size. Most of the people dont care about this in home audio.
2. Cost. Many people dont care. And its not as if the smps amps are cheaper to purchase.
3. Efficiency. People dont care. They actually aim for tube amps or class A amps at some point of time in life, so efficiency is irrelevant.
4. Regulation. For lower power supplies, even a linear regulated supply gives you that.

Cons:
1. Noise. This scares people. Sure it can be done without noise, but how will one know.
2. Technical complexity. A fault in linear supply is easy to detect and fix. All you need is a dmm. Secondly, a really good designer is needed to do a good smps, Its very difficult for an average person to make sure that his amp has a good smps. For linear, even an idiot can check the caps and trafo ratings etc and do some basic calculations to make sure his supply is good.


Feel free to add more.

The way you have shown SMPS in negative light and making it look like "Not Needed" is commendable. hyeah:

Take a case of class-A amp with 50 watts. Ignore the COSTS. Look at it from technical point of view with following points.

1: Linear supply needed should be atleast 300W continuous rated because of constant loading of supply in class-A--->>> Large format Ironcore is needed with thicker copper windings, not at all a Greener solution by any means because of wastage of copper as precious metal.

2: It will not give you any power factor correction, will suck the mains current in form of peaks which will contaminate it with spray of harmonics and resulting in clipped sinewave of AC mains. You are making the supply line dirty.

3: You will need large amount of filter storage capacitors along with big iron chokes which again add to weight and excessive use of copper windings. Resulting in heat. And still you won't achieve more than 30dB of wide bandwidth ripple rejection with it.

Now compare it with SMPS

1: You get PFC, the mains current draw is ultra linear, you are using one whole sinewave cycle to charge the capacitors. Mains contamination is bare minimum because of 3 order PI stage EMI filter network required by EN61000 directive.

2: You get regulation and much more reliable operation from 90VAC to 270VAC, let the mains fluctuate, your equipment wont DIE due to this.

3. You use 1/20th mass of copper windings [compared with windings of conventional trafo]. Less heat, better current response and best thermal headroom for class-A. Efficient use of resources, a greener way for the planet.

4. You get ZERO HUM in your class-A amp, no need of any large bulky expensive filter chokes which can't match with such a high value of ripple rejection and noise free supply. [Equally mandatory for tube amps which are humming and band-aids are applied in DHTs to make them hum free but fail]



If someone still prefers a flawed topology design with drawbacks just because its simpler[ Also claims that its superior]and simply ignores the best design format available just because it is complex and needs an able designer to do it, i have zero objection in this, Go Ahead.........


Kanwar

 

[captrajesh]

For a layman like you, it could be difficult to believe that this could be the cause[Because you don't have technical background in order to grasp the difference of level of technical innovation implemented and achieved in smps Vs linear supplies], but given my technical background i have seen and have experienced such things alot. Let alone a PFC stage, i have seen people lacking in basic smps design topologies. They don't even know which topology is best and they will implement audio smps with FLYBACK topology, one example is ICEPOWER modules used in JEFF ROWLAND and BELCANTO, both have SMPS topology which is FLYBACK converter based its one of the worst to be used in audio because of its flawed EMI radiation.

I'm not undermining the fact that certain expertise is required to design proper SMPS.

The point is, if companies making medical equipment could afford to hire experts to design SMPS to suit their equipment, why (at least) big companies in the audio business cannot afford to hire experts for designing seemingly cheaper and superior SMPS for their audio equipment rather than linear power supplies for making which no knowledge would be required; plain simple logic of "layman" would suffice IMO.

 

[kanwar]

I'm not undermining the fact that certain expertise is required to design proper SMPS.

The point is, if companies making medical equipment could afford to hire experts to design SMPS to suit their equipment, why (at least) big companies in the audio business cannot afford to hire experts for designing seemingly cheaper and superior SMPS for their audio equipment rather than linear power supplies for making which no knowledge would be required; plain simple logic of "layman" would suffice IMO.

IMHO,

The stigma attached to SMPS[bad repute from past] is the culprit and sticking with traditional approach as they don't want to take risks. Along with the inadequate exposure to the innovations happening at present in SMPS Tech field is responsible. Smps were bad in past, not any more, times have changed, one should also change his/her mindset along with it.[I agree, you guys are yet to see anything like that in home audio.]

Else i could not see any other reason.

 

[haisaikat]

For lower power a dedicated SMPS is not costlier than those fancy linear supplies projected as something exotic by so called high-end manufacturers.

In my personal opinion, i would like to go with a hybrid mix of SMPS + Linear supplies in very high quality audio applications with lower power range [preamps/DACs]. In such case, a linear mains Balanced auto-transformer will be used to step down the mains voltage from 220VAC to somewhat lower value say 24V and then using choice of switching for isolation and linear regulators to do rest of the job. This type has several advantages when the power consumption is less than 100W such as low cost and optimum use of various advanced technologies which are meant for low power by keeping the costs down.

Okay thanks but there is another school of thought I came across, there are some products like JKDAC32 which uses built in battery and claim that it gives much purer form of the myth named "linear power". In fact JKDAC32 now offers a add-on module which trickle charges its battery while in use. Would this not be a better and cheaper option that costly linear power supplies?