Sir Serengetiplains,
I have nothing against SMPS. Understand the rationale - efficiency, area and weight (the transformer is smaller). However, unless its designed by reputable SMPS designers I wouldn't be going that route just yet. I don't expect an audio electronics company to be good at designing SMPS also. Very different field.
Rascal101
I have nothing against SMPS. Understand the rationale - efficiency, area and weight (the transformer is smaller). However, unless its designed by reputable SMPS designers I wouldn't be going that route just yet. I don't expect an audio electronics company to be good at designing SMPS also. Very different field.
Rascal101
rascal101 said:
Come on.......that statement requires modification...In defence... I use and design switchmode technology in audio... ....Ripple and noise aren't issues anymore with good components and designs. Some switching mode topologies have noisy reputations but it is simple to choose another. It may more costly to produce.
I use a 75Khz 1 kW boostmode power factor corrector as the 530V B+ supply in my tube power amps, also a push-pull low voltage converter ....both are far quieter in terms of emitted pollution than the poorly screened flyback psu used in most satellite down receivers and other consumer products from the far east.
Commercially made units may just scrape through compliance to EMI standards but since much of todays music goes through circuits using similiar technology, i.e digital processing and oversampling algorithms....one can't avoid switchmode anymore.
richj
I said that SMPS do not have a home at high end audio because I don't believe a good number of people who design audio amps are also good at SMPS. Insofar as SMPS companies, there are hundreds all over the world. But it doesn't mean these companies produce a good design. I come from an SMPS company and I do see the designs. While I have not designed a full power supply yet (just pieces eg PFC, inrush ckt etc), I noticed that even seasoned design engineers are not completely familiar with all parts of the power supply. We have a consultants for magnetics, DC-DC, PFC, EMI etc. Depends on the output power - higher output = more consultants. Typically we have 1 in a typical project depending on the need.
Speaking of SMPS in audio application, yes its true we're seeing more and more and it will just be a matter of time. However, I don't believe it is this time just yet.
ok rascal....too true....to design a smps with all protective features takes alot of practical and theorical experience in physics and magnetics and most of todays engineers lack both in depth and magnetics (sadly) is still a black art subject. I'm from the old school of thought when a university degree was worth something, not like the ones obtainable now.
richj
richj
Jan, there was a number of them both before and after, in their high-end lineup as well as the regular consumer stuff. I've seen and heared a number of them, and in fact own a TA-N88B. The switchmode power supply used in them is not as advanced as todays designs (and all discrete), but it does the job very well. It is an extensively shileded (has it's own sealed box) two step design, with a buck regulator in front of a self-oscillating push-pull cpnverter. I did however notice the propensity to produce acustical noise rather than electrical, a faint hiss perceptible only in very quiet conditions (like in the middle of the night). There were some issues with reliability, though - due to much worse filter cap technology, compared to what is obtainable today - anyone who ever designed a SMPS already knows what I'm talking about.
ilimzn said:
Yes indeed, my experiences with the -88 are similar to yours. In fact, I got two, both broken (the smps part). One I was able to repair and is functional, the other one is still waiting for me to find a quiet day to trouble shoot. Probably Wednesday morning 2007...
The case is a study in RF and EMI engineering and I find the same metal "finger" seals I saw when working on Air defense radars many moons ago.
Jan Didden
janneman said:
fwiw == you can purchase the finger stock at Surplus Sales of Nebraska: http://www.surplussales.com/ (they also have a huge assortment of polystyrene caps).
Just to put something tangible to the discussion: the attached is from the Vicor website. Output ripple from smps, top is from supply itself, bottom after going through a R(ipple) A(ttenuation) M(odule). Bottom one is 1.5mV RMS. Not bad at 10A load, eh! If it just was a tad less expensive and/or I were a millionaire....
Jan Didden
Jan Didden
richwalters said:
Rich I agree with you 100%.....
I don't mean to sound arogant but at all the companies I worked at doing SMPS design...their design gurus were morons....they had basic understanding of things with no understanding of advanced magnetics and physics and I would try to explain control loop theory to these guys 100 times and it wouldn't sink in....SOme of these guys are afraid of math and can't follow some second order diff equations... I scratch my head thinking how did this shmuck get a degree....
I am venting here, because in many cases I wind up doing all the work while these guys screw around in the lab contributing very little... Some of these companies are pretty big names....
cerrem
switching noise.do u have 'audiophile' ears?30khz is inaudible to humans!
Its obvious that you cannot hear beyond 20KHz. However, signals beyond 20KHz according to this study is relevant to the perception of an audio signals
- Tsutomi Oohashi, Emi Nishina, Norie Kawai, Yoshitaka Fuwamoto, Hiroshi Imai, High-Frequency Sound Above the Audible Range Affects Brain Electric Activity and Sound Perception. Audio Engineering Society preprint No. 3207 (91st convention, New York City). Abstract, page 2
This is also mentioned in the ff: paper
There's life above 20 kilohertz! A survey of musical instrument spectra to 102.4 kHz
Just to put something tangible to the discussion: the attached is from the Vicor website. Output ripple from smps, top is from supply itself, bottom after going through a R(ipple) A(ttenuation) M(odule). Bottom one is 1.5mV RMS. Not bad at 10A load, eh! If it just was a tad less expensive and/or I were a millionaire....
Jan Didden
Those are nice hybric thickfilm modules. Pretty much bullet proof, I used them in an avionic job before. They have pretty clean ripple to work with ie not that much hash and noise (resonant mode).
From your attached chart > 20LOG(10/74) Filter module has about 17 dB of ripple attenuation. The switching freq is about 200 KHz so a filter at 20KHz should work. I'm sure they have common mode filters as well.
That's probably true. And heck, I'm probably the only member who's ever built a class D tube amp.
http://www.diyaudio.com/forums/tubes-valves/110155-blasphemy-im-sure.html
Far more adventurous than SMPS for audio, I have built a supply for an eventual tube oscilloscope project (which should resemble an early Tektronix when I'm done). A 5MHz bandwidth with 50mV/div sensitivity is most certainly enough to "hear" all the noises of an SMPS operating at 100kHz.
http://www.diyaudio.com/forums/power-supplies/153635-tube-scope-supply-board.html
I haven't started on the oscilloscope yet, but if it works out, it will be utter and complete proof that SMPS are suitable for high fidelity audio.*
*And for those who like "hi-fi" instead, you can still put a resistor in series to get "That Tube Sound" from the PSU droop. You'll still get the advantage of low line ripple, regulated heaters and soft start.
Tim
Chris / cerrem, a question
Greetings,
I have built a resonant SMPS using the L6599 controller to provide 225mA @ 450Vdc.
The resonant frequency is 150kHz (120-180kHz bandwidth for regulation purpose). However, I saw on my scope that the 100Hz (50Hz mains here) ripple reaches 1V pk-pk. Which I deem unsuitable for HiFi purpose. (My CLC - 110uF+10H+110uF - power supply has only 0.3V pk-pk.)
The SMPS has 2x220uF to filter the rectified mains. Any idea how to get rid of the ripple? Thanks.
Serge
Greetings,
I have built a resonant SMPS using the L6599 controller to provide 225mA @ 450Vdc.
The resonant frequency is 150kHz (120-180kHz bandwidth for regulation purpose). However, I saw on my scope that the 100Hz (50Hz mains here) ripple reaches 1V pk-pk. Which I deem unsuitable for HiFi purpose. (My CLC - 110uF+10H+110uF - power supply has only 0.3V pk-pk.)
The SMPS has 2x220uF to filter the rectified mains. Any idea how to get rid of the ripple? Thanks.
Serge
Are you using a p-p amp; if so, ignore the ripple issue as the ripple cancels by the opposing halves in the o/p tranny. I allow 4v p-p 100Hz ripple without any illeffects solong both o/p tubes take sim currents.
richy
Hi Richy,
Thanks for the reply.
I use a PP amp. The first two stages are differential pairs with ccs.
I'll have to try my smps on the amp. There is also a concern about reliability. My brother repaired our grand-parents'radio. After more than 40 years, the psu is still ok. But with integrated circuits, transistors... one day they are fine, up in smoke the next day.
Serge
Thanks for the reply.
I use a PP amp. The first two stages are differential pairs with ccs.
I'll have to try my smps on the amp. There is also a concern about reliability. My brother repaired our grand-parents'radio. After more than 40 years, the psu is still ok. But with integrated circuits, transistors... one day they are fine, up in smoke the next day.
Serge
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.