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History of SMPS in audio ??
History of SMPS in audio ??
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Old 6th October 2010, 02:39 PM   #1
birdyman is offline birdyman  United States
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Default History of SMPS in audio ??

I am just curious. Who was first to use SMPS in power amps?
I know Carver used smps in his PM2.0t in 1980's?? QSC?
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Old 7th October 2010, 12:16 AM   #2
Enzo is offline Enzo  United States
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PM2.0 was a switcher? I don;t recall that. Then again I don't recall a lot anymore. Carver used multiple power supply voltages and switched them in and out as needed, but that is not SMPS. And they have that whole "magnetic resonance" triac controlled power transformer, but that too is not SMPS.

The QSC Powerlite was their first SMPS amplifier that I can think of. Then the PLX series. Again, the earlier amps with multiple power supplies switching in and out are not SMPS designs.

Switched Mode Power Supply refers to the power supply itself, not what the amplifier circuit does with the power.
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Old 7th October 2010, 01:02 AM   #3
Krisfr is offline Krisfr  United States
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Infinity had one I think not sure what year, it was at a CES Chicago Style if my memory serves me, it loses a lot of memory from time to time...
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Old 7th October 2010, 01:33 AM   #4
abraxalito is offline abraxalito  United Kingdom
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Stereophile says Chord's original SPM900 was released in 1989.

Stereophile: Chord SPM 14000 Ultimate monoblock power amplifier
'The total potential here must be nothing less than astronomical.'
'Nothing less. The number 10 raised almost literally to the power of infinity.'
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Old 10th October 2010, 06:27 AM   #5
dangus is offline dangus  Canada
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History of SMPS in audio ??
Default Technics used SMPS in 1979

Technics built some compact stereo components around 1980. The SE-C01 power amp had a switching supply, and was probably introduced in 1979. It is listed in the Audio October 1981 Annual Equipment Directory (40 watts/channel, $400 list price). (Winter 1980 Consumer Guide "Stereo & Tape Equipment" says list was $360, low retail price was $270.)

(By the way, I have one, along with the matching preamp and tuner. The amp doesn't work. If someone happens to have a service manual or schematic, please let me know.)

Ben Duncan's "High Performance Audio Power Amplifiers" book doesn't say who used SMPS first, but mentions Sony using one in a Class D amp in the late '70s.

One could argue that vibrator power supplies in battery powered tube gear were switching supplies, although I don't think they ran at particularly high frequencies.

Last edited by dangus; 10th October 2010 at 06:38 AM.
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Old 10th October 2010, 09:19 AM   #6
analog_sa is offline analog_sa  Europe
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As a teenager i owned a Sony in 78' or 79' which used a very simple SMPS. It was by far the worst sounding amp i owned at the time and the SMPS blew up at least twice but wasn't hard to repair as it was entirely discreet. The amp itself was AB.
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Old 12th October 2010, 06:19 PM   #7
blmn is offline blmn  Brazil
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Ok, they were self oscillating types, but I remember some car audio power amps circa 80īs beginning or even late 70īs that use SMPS.

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Old 12th October 2010, 07:20 PM   #8
LAJ is offline LAJ  United States
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Default I wouldn't own one personally.

I used to work at a sound shop. People would bring in Powerlites all blown up.
An output would short and take out the power supply with it. The IGBTs would blow up and vaporize traces on the board. It looks like a grenade went off inside the amp. The rebuild kit for just the power supply is $80. I can tell you after rebuilding the (smt) power supply that the circuit board would probably not take another rebuild. I thought it was the poorest built amp that I had ever seen.
If they are used by professionals they might be all right. I know of a gogo bar that uses them and they have never failed. But I know of churches that have bad wiring for their speaker system and they blow them up all the time.
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Old 12th October 2010, 07:39 PM   #9
wrenchone is offline wrenchone  United States
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Infinity had their switch-mode amp with switch-mode powers upply in the mid-70's. It was 200W/channel if I remember correctly. I recall hearing about it when I was still in school. A few years later, I encountered an engineer that worked on the project. He said that the amp used a pair of Solitron high speed BJTs in the output stage, and the power supply had a big problem with bass "pumping", where the energy stored in the woofer got fed back to the power supply through the output commutation diodes and pumped up the power supply rails. This amp (or the rumor of it, as I never saw one) was one of the inspirations that that led me into a career in SMPS design. Now i design and build linear amps for a hobby - go figure.
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