So; the bottom line seems to be:
DVD/CD/SACD/DVD-Audio Players with "Switchmode" power supplies absolutely SUCK for Audio; unless they are "Modified".
Stand alone CD/SACD players with "Linear" power supplies are the absolute best for Audio.
Video circuitry and switchmode power supplies have absolutely no place with High-Quality Audio Reproduction.
DVD/CD/SACD/DVD-Audio Players with "Switchmode" power supplies absolutely SUCK for Audio; unless they are "Modified".
Stand alone CD/SACD players with "Linear" power supplies are the absolute best for Audio.
Video circuitry and switchmode power supplies have absolutely no place with High-Quality Audio Reproduction.
jackinnj said:
ChuckT said:
Hi all,
I have never seen a switcher quiet enough yet. Do not only consider DM noise but also CM noise currents and magnetic coupling.
1 mV induced noise will give 1 ps of jitter in an average inverter circuit (read the standard oscillator used in CD players)
963: Connect left and right main speakers to front outputs rather than stereo outputs
Clock circuitry is a real drama, I am trying to understand the architecture, if any exists.
Will keep you updated
regards
jackinnj said:
Hi
I adapt my measurement speed on possible temperature effects, which have typical time constants of uS, in the case of AD797
LM317: That noise is easy to measure (the level depends on the DC load, yuck !)
Once you are >30dB down that level it becomes more difficult.......
regards
It was late when I wrote the previous post. I forgot to add that my error was thinking of current as constant. In this case, the rate of change is exponential and so the dB change is also higher.
🙂ensen.
🙂ensen.
As I´m interested in a car-audio setup since recently and want to build a small low-power switch-mode power-supply feeding a couple of op-amps (+/- dual rails) to roll my own active crossover/ equalization, I searched this board for possible solutions.
I came across various posts from "jackinnj" where he (as here also) repeatedly recommended the LT1533.
Thereupon (thanks jackinnj!) I finally searched the web and read some lenghty data sheets and application notes and it seems (I`m anything but a switch-mode-power-supply expert - to be true - I have no clue ...hey.. am I a poet?
) that this part indeed has outstanding qualities not only as a switch mode part but can even challenge good linear designs. Take a look particular on the LT AN-70 Application-Note. Almost at the end (Appendix K) there is are interesting measurements of how an 16 bit A/D converter powered from an LT1533 switch-mode power supply compare to powered from a bench-power-supply (I assume it`s a high quality linear regulated design).
Untill now I have not wasted a thought about switch-mode but now I`m surprised how good it actually can be.
Maybe that the performance still is not good enough for some very high-end audio applications but "high-quality" it really seems to be (at least to me).....yet again
. Switching-regulator design lowers noise to 100 µV
LT1533 datasheet
LT AN70 Application Notes: Monolithic Switching Regulator with 100µV Output Noise
BTW and off topic: does somebody has a PCB-layout (or can give me a link where I can find one) with the LT1533 and for my mentioned purpose above. As I said I have no clue about SMPS design and I guess layout is very crucial with this and with my big knowledge possibly I`d only mess up a few things when I try it by myself.
cocolino said:
Hi
Forget about switchers if you are not experienced, uness you want to muddle up the sound. Even experienced designers (including myself) are not able to cut the noise down to a required level.
Funny by the way that even "designers" (linked in your previous mail) are not able to correctly specify noise. Use:
Volts AND specify the bandwidth of measurement (Hz)
or
V per Sqrrt Hz
All other specifications are utter nonsense !
regards
mrfeedback said:
I was reading through Pressman's "SMPS Design" -- the chapter on error amplifier stabilization -- it would appear that just switching to LOW ESR caps may result in some unintended consequences -- one of which is to lessen the feedback loop's ability to remove 120Hz (100 Hz in Europe) hum.
Specifying all of the components in the supply and regulation loop seems to be a combination 85% science and engineering, 15% art.
I wonder how many psychiatric wards are inhabited by former SMPS designers.
My biggest gripe about SMPS's is that the most expensive failures I've had in commercial AV products was when the SMPS in as rear projection unit crapped out taking other components with it.
I guess randomly replace caps in a SMPS is not a good idea. Can anybody tell me the possible location of a cap in a feedback loop in a SMPS.
I also have a problem location the datasheet a Motorola switching controller chip. The part no on the chip is "TY72011AP2 CPCD0315". Nothing turns up on the Onsem site.
Also, I read somewhere that mentions the Linn CD12 uses some form of SMPS, is this true?
I also have a problem location the datasheet a Motorola switching controller chip. The part no on the chip is "TY72011AP2 CPCD0315". Nothing turns up on the Onsem site.
Also, I read somewhere that mentions the Linn CD12 uses some form of SMPS, is this true?
ChuckT said:
The response curve of the error amplifier, the transistors and all the passive componenets has to be very high at DC through a few hundred Hz, but then slopes down -- at one rate (-2) to the point where it is critically damped, and then at a lesser rate (-1) through the next decade.
So the first couple capacitors in the feedback loop of the error amplifier itself so that the gain decreases with frequency.
I hvae never bothered to open up my LP12.
Huh? I won't pretend I know what you are talking about?🙁
Time for some googling. Let see, "feedback", "smps", and ....
Time for some googling. Let see, "feedback", "smps", and ....
smps linn
Yes the Linn CD12 has an SMPS powersupply as well as a lot of other Linn gear, the whole Klimax range use SMPS for an example.
Yes the Linn CD12 has an SMPS powersupply as well as a lot of other Linn gear, the whole Klimax range use SMPS for an example.
And so does the LK85, the LK140, the 5125, the 2250, the klimax twin, the klimax solo and the classik serie.
Isn't it TDA7293 in some of them and TDA7294 in some?
Regards Mikael
i'll have to crack it open again
i have biamped Kelidh's driven by the Majik, and LK100 -- this is this the unit I use for purposes of domestic tranquility, if you know what I mean. The amps I build are with the kids in college or in the basement.
Jack
i have biamped Kelidh's driven by the Majik, and LK100 -- this is this the unit I use for purposes of domestic tranquility, if you know what I mean. The amps I build are with the kids in college or in the basement.
Jack
jackinnj said:
Yes, I know about this, and these stability considerations apply to linear regulator supplies also.
In the case of the DVD smps, the originals were low esr but of unknown (doubtful) quality.
The Hitano replacements I used are known to be good, and in this case effected sonically nice improvement.
I think that with most mass produced smps modules as used in modern DVD players, the circuits are configured to be reasonably tolerant of component drift/tolerance and in cases like these the result of better caps is to reduce broadband noise output on the DC rails as is my experience.
These modern DVD players and their supplies are built to a (lowest possible) price, so capacitor quality just good enough to do the job is specified, and high quality low esr caps are out of BOM budget.
Eric.
Clean Power Supply
Would this post provide the solution?:
http://www.audioasylum.com/audio/tweaks/messages/91675.html
Would this post provide the solution?:
http://www.audioasylum.com/audio/tweaks/messages/91675.html
Hello,
I would like to comment on some of the remarks made in this thread.
First of all why does a company use switchmode powersupplies? The only reasons are cost and mandatory idle power consumption regulations. As long as a CD-player performs well enough it is good enough. This is certainly not the same objective as striving for the best audio quality. So a good analog power supply is the best. See the comments of Guido regarding EMC.
Regarding the power supply quality of a Cd player there are basicly three blocks of power use you can distinguish.
-Servo power use. Mostly already good enough. If you play clean undamaged discs it is OK. If you have a lot of scratched discs you might improve a litle but then the data stream will not be of best quality (due to the scratches) resulting in non optimum audio quality. So improvements are hardly worthwhile but won't hurt either.
-Digital power use. Yes, a good powersupply simply gets the best digital signal quality.
-Analog Audio power use. Use your ears to determine the point where you stop improving.😉
Although it seems obivious that you should not forget the other design rules while improving your CD player.... I once got a very high end CD player to compare it with the internal Philips refferences. The expectations of the company offering that product for testing were very, very high. However it turned out that due to improper separation of the HF-signal coming from the cdm the playability quality was comparable to a clock-radio with built in CD player....
Ward
I would like to comment on some of the remarks made in this thread.
First of all why does a company use switchmode powersupplies? The only reasons are cost and mandatory idle power consumption regulations. As long as a CD-player performs well enough it is good enough. This is certainly not the same objective as striving for the best audio quality. So a good analog power supply is the best. See the comments of Guido regarding EMC.
Regarding the power supply quality of a Cd player there are basicly three blocks of power use you can distinguish.
-Servo power use. Mostly already good enough. If you play clean undamaged discs it is OK. If you have a lot of scratched discs you might improve a litle but then the data stream will not be of best quality (due to the scratches) resulting in non optimum audio quality. So improvements are hardly worthwhile but won't hurt either.
-Digital power use. Yes, a good powersupply simply gets the best digital signal quality.
-Analog Audio power use. Use your ears to determine the point where you stop improving.😉
Although it seems obivious that you should not forget the other design rules while improving your CD player.... I once got a very high end CD player to compare it with the internal Philips refferences. The expectations of the company offering that product for testing were very, very high. However it turned out that due to improper separation of the HF-signal coming from the cdm the playability quality was comparable to a clock-radio with built in CD player....
Ward
It is well understood that linear is the best way, but for efficiency (less heat), lower operating costs and plain old physical smallness, SMPS cannot be beat.
That said, opamps are getting better and better PSRR so at some point in the future, having linear supplies will be overkill and just plain bad for the planet (power plant pollution). Most consumers can't even hear the diff, which is why the fabs put them in. Still, what about an SMPS for efficiency, then into a power opamp for PSRR and then into the audio circuits?
🙂ensen.
That said, opamps are getting better and better PSRR so at some point in the future, having linear supplies will be overkill and just plain bad for the planet (power plant pollution). Most consumers can't even hear the diff, which is why the fabs put them in. Still, what about an SMPS for efficiency, then into a power opamp for PSRR and then into the audio circuits?
🙂ensen.
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