Why so little use of SMPS in commercial amps? - diyAudio
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Old 3rd January 2010, 03:41 AM   #1
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Default Why so little use of SMPS in commercial amps?

Most commercial amps still seem to be using bigass transformers instead of SMPS designs. I'm a bit perplexed as to why - it seems that it's not all that hard to reduce noise down to inaudible levels with a bit of clever design, while the elimination of a big, expensive transformer can save a lot of cash.

So, where's the SMPS designs?
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Old 3rd January 2010, 08:11 AM   #2
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Thats right, I agree with you.

But it dosent mean tha they are unable to develope High End SMPS.

But I cant explain why.

Crown MA5002VZ, only switched to SMPS in the past few years, it was big toroidal transformers.

the KV2 audio I have still USING the big transformers.

Thats a designer mind
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Old 3rd January 2010, 08:41 AM   #3
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The simple answer is probably that regular transformers are extremely rugged and well understood. If you decide to go the SMPS route you need to design for the peak power draw or run the risk of the power supply going into protection or blowing up. A regular transformer can withstand momentaneous power draw several times above it's rated power, so you can get away with a nominaly under-sized transformer.

Sad, but true.
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Old 4th January 2010, 12:52 AM   #4
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Development time costs as well, and to build a good, reliable and low EMI SMPS with good enough properties for audio is not that easy.
On the other hand, power transformers are not so expensive, so apart from weight there is not so much to win for powers of below 500W.
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Old 4th January 2010, 11:50 AM   #5
marce is offline marce  United Kingdom
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As stated EMC is one of the major concerns, design time, layout etc plus with high powered SMPS direct from mains you quite often have 300+ volts D.C floating about so isolation for the various low voltage standards becomes an issue. Even though the transformer is much smaller, you have the production costs of all the other components required for the SMPS. Even though the actual cost of these components is relatively low, they have to be placed, soldered inspected etc which can soon push costs up depending where the products is manufactuered (UK Electronic Assembly is approx 90-120 per hour), plus EMC testing etc.
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Old 4th January 2010, 01:09 PM   #6
Glowbug is offline Glowbug  United States
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Quote:
So, where's the SMPS designs?
In the 12V world
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Old 4th January 2010, 07:12 PM   #7
Eva is offline Eva  Spain
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The price of copper and the metals used in the cores of toroids is rising, and at the same time the requirements for compact and light weight equipment are increasing, so the way in which audio amplifiers are designed is progressively changing.

For very high power applications, where output voltage is also high and dangerous like mains input voltage, the future is probably no transformer at all.

For lower powers, SMPS.
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Old 5th January 2010, 03:02 AM   #8
Enzo is offline Enzo  United States
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To have an SMPS, you have to engineer one, and the design skills for the high power SMPS are not the same as for audio circuits. There may be nuance to linear power supply design, but the process is familiar to most any engineer already on staff.


MAny consumers associate weight with quality.

This is not unlike the sound effects engineered into your American car doors. Car doors could safely and reliably simply click shut, but consumers are more comfortable with a big KA-Chunk sound.

Any number of the SMPS I find in professional audio gear will handle a dead short across the power rails. They just shut themselves down.
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Old 5th January 2010, 03:32 AM   #9
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Quote:
Originally Posted by runebivrin View Post
The simple answer is probably that regular transformers are extremely rugged and well understood. If you decide to go the SMPS route you need to design for the peak power draw or run the risk of the power supply going into protection or blowing up. A regular transformer can withstand momentaneous power draw several times above it's rated power, so you can get away with a nominaly under-sized transformer.

Sad, but true.
Actually, you have to design for both peak and minimum current -- it's like the old "dog food" linear programming problem where you had to learn how to optimize a design within some constraints. I've mentioned this before (search the "wayback machine" Rocky) -- Sanjaya Maniktala has done a really nice power point on SMPS magnetics which can be found on the Nat Semi website -- search under his name.
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Old 5th January 2010, 05:13 AM   #10
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IMHO, it's entirely customer acceptance. People expect a powerful amp to have some mass. I don't know if there's really a cost savings in terms of parts, but shipping iron around has gotten expensive.

CH
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