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  1. #61
    John,

    Thanks a bunch for sharing your power supply with us. I recently got around to putting it together and am very impressed with the sound my Touch is producing. I just don't understand how a power supply can have such a profound affect on the sound that a piece of equipment produces.

    Anyway much thanks and highly recommended.

    Mark

  2. #62
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    Quote Originally Posted by mjock3 View Post
    John,

    Thanks a bunch for sharing your power supply with us. I recently got around to putting it together and am very impressed with the sound my Touch is producing. I just don't understand how a power supply can have such a profound affect on the sound that a piece of equipment produces.

    Anyway much thanks and highly recommended.

    Mark
    I have Mark's power supply on loan right now. I am completely amazed how well this power supply performs. I currently use a stock Jerome linear, and I have heard the Bolder modded Jerome in my setup. This power supply is significantly better in every way. I'm having a hard time even listening with the Jerome in place again. I'm going to either build this supply myself, or get one of my electrical engineer friends to build it so it's pretty (and done properly).

    Terry

  3. #63
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    Hi all,

    I have a SB Classic on the stock power supply and did some Googling but all the LPS I've seen mentioned I can't find by part number anymore.

    Does anyone know of a good budget LPS I can use with a SB3?

    Not interested in the Bolder or RWA mod, just something to tinker around with and compare against the stock PS.

    Thanks.

  4. #64
    Hi Sandy,

    Here is a inexpensive Jerome one that is a step up from the stock. It is linear power supply. You would need to put on a new connector and figure out which wires were for the 5 volt supply. Here is a link: http://www.herbach.com/Merchant2/mer...egory_Code=PWS

    Mark

  5. #65
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    Dear John

    You seem to have quite a following in your non science of acoustics and power supply design. Are you even qualified in any of the fields of electronics you comment on weekly?

    I have designed power supplies for the last 25 years for audio and high end medical equipment and can only describe your postings as pants.

    In the EU, power supply designs are very stringent on emissions, so to say a linear supply is better is totally non scientifically proven to be better than switchers in the audio band. Modern switchers when properly designed are far superior to heat generating linear supplies.
    Last edited by Waldo Pepper; 2012-01-17 at 12:57.

  6. #66
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    Quote Originally Posted by Waldo Pepper View Post
    You seem to have quite a following in your non science of acoustics and power supply design. Are you even qualified in any of the fields of electronics you comment on weekly?

    I have designed power supplies for the last 25 years for audio and high end medical equipment and can only describe your postings as pants.

    In the EU, power supply designs are very stringent on emissions, so to say a linear supply is better is totally non scientifically proven to be better than switchers in the audio band. Modern switchers when properly designed are far superior to heat generating linear supplies.
    For those not familiar with U.K. slang: http://dictionary.cambridge.org/dict...ritish/pants_2

  7. #67
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    Quote Originally Posted by mjock3 View Post
    Hi Sandy,

    Here is a inexpensive Jerome one that is a step up from the stock. It is linear power supply. You would need to put on a new connector and figure out which wires were for the 5 volt supply. Here is a link: http://www.herbach.com/Merchant2/mer...egory_Code=PWS

    Mark
    Thanks .. any other options I can look at?

  8. #68
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    Quote Originally Posted by Waldo Pepper View Post
    You seem to have quite a following in your non science of acoustics and power supply design. Are you even qualified in any of the fields of electronics you comment on weekly?

    I have designed power supplies for the last 25 years for audio and high end medical equipment and can only describe your postings as pants.

    In the EU, power supply designs are very stringent on emissions, so to say a linear supply is better is totally non scientifically proven to be better than switchers in the audio band. Modern switchers when properly designed are far superior to heat generating linear supplies.
    Unfortunately I don't have time to make a full reply to this, its going to take some time to do it justice, I don't want to make a quick and dirty reply which does not fully represent my experience and research in this matter. I'm not blowing you off, I really do want to make a thorough and in depth response to this, but it's going to take some time to put it together, I don't want the reply to be pants as well, maybe at least a shirt.

    John S.

  9. #69
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    OK, here is the in depth reply to Mr Pepper's inquiries.

    I am an electronics engineer working for a semiconductor company (I'm not allowed to say which one), I layout integrated circuits, mostly large high speed digital with sensitive analog circuitry as well. My specialty is power distribution networks in these chips, providing low noise power and ground networks to provide very low jitter on the interface between the digital and analog sections. This jitter needs to be kept in the single digit ps range, which is not easy. In order to meet this we need on chip regulators, these regulators are always linear regulators, switching regulators simply produce too much noise.

    At the system level we usually have a switching regulator on the board, followed by a linear regulator on the board and the linear regulator on chip. This is required in order to keep noise levels low enough so we can meet the jitter requirements. Believe me, if we could get away with a switching regulator on the chip we would do so.

    As to my personal experience, I have designed many switching and linear regulators, I have only designed a few switching AC mains to DC supplies, but I have worked closely with those that do. I have measured many switching supplies, I have a fairly good good idea of what they can and cannot do. I have designed many linear AC Mains to DC supplies and measured those as well.

    As to how this relates to audio, that is a long saga. Many years ago I was building audio DACs for myself and found out that what power supply I used had a significant impact on the sound. I set out to find out what differences in these supplies caused the difference. I ran many hundreds of tests with different supplies, listening and measuring the supplies and trying to come up with correlations, it was not easy and took a couple of years. One thing I learned from these tests was that most supplies feed a fair amount of noise back into the AC mains as well as the noise feed to the audio circuits. This noise injected back into the mains turned out to be one of the most important aspect of the tests, and one which is frequently completely ignored in power supply tests.

    It turned out that frequency range that caused the most impact on sound quality was the 40KHz to 200KHz range. MHz and up was usually well controlled and filtered, and frequencies in the audio range were usually handled very well by the regulators in the circuits, but the intermediate frequencies were not well dealt with. And it was the amount of this noise injected back into the mains that had the most impact on sound quality, presumably by being carried to other components in the "stereo system" such as power amps and preamps. I tried this with many different audio systems, from inexpensive consumer systems, expensive audiophile systems, pro audio systems and all of them seemed to be susceptible to this incoming noise on their AC.

    Many of these components contained "line filters" designed to block incoming noise, but most of those only seemed to be effective in the MHz and up range, having very little affect in the 40KHz to 200KHz range. I probed around inside these other components and watched what happened to this noise coming in over the AC mains and found many of these components actually had resonances in this range which significantly magnified incoming noise. In quite a few cases even if their own power supply was not generating noise in this region, the resonances wound up feeding significant noise into the circuitry when noise in the right range was on the AC.

    So the summary of all these tests was that the biggest requirement for a PS was to not send noise in the 40KHz to 200KHz range back down the AC line, keeping noise out of the DC fed to the DAC also made an impact, but it actually was not as big a concern as what went to the mains. It also had to not be susceptible to noise in that range coming from OTHER components.

    So I set out to design a PS that met these goals. Since this was going to be a onesie for my own use it was a lot easier to build a linear supply. I did a LOT of spice simulations trying out different topologies and components which eventually evolved to what I have today. I built several and proved that the real world did in fact closely match the spice results so I was quite confident that doing the exploration with spice was a reasonable approach.

    The result is very different than most linear supplies. Most linear low voltage supplies employ a single stage very large value cap after a bridge regulator. This of course only conducts over a very narrow portion of the cycle, giving rise to very high current pulses in the transformer. Common rectifiers produce switching noise in the bad frequency range, with in conjunction with the current pulses cause the power transformer to ring like a bell right in the bad range. This noise goes right through the power transformer and into the mains. Even if you have a good regulator which blocks this noise from the circuit beeing fed from this supply, the noise still goes out to the mains.

    My design attempts to alleviate these issues in several ways, first it uses Schottky rectifiers, second it uses a choke based asymetrical PI filter after the rectifiers. The first cap is much smaller than the second cap. The result is a supply which has cunduction over almost the entire cycle, thus no large current spikes. Having the small first cap allows the large conduction angle, but it also allows the filter to not need nearly as much minimum current as a true choke input filter. What comes out of the filter is almost pure sine wave which is very easy for the regulator to deal with. In a tgraditional linear supply the sawtooth output has a lot of high frequencies which are much harder for simple regulators do deal with. The third part is a damping network across the power transformer which damps the winding resonance so it will not resonante from noise coming in from the outside world.

    The result of all this is a design which has extremely low noise injected back into the AC line and very low noise sent to the audio circuitry. It's simple, does not contain any custom components, no special "audiophile" parts, is easy for inexperienced DIYers to build. Is it the only design possible? of course not. Can a switching supply be made which can match this performance, almost certainly. But its not going to be nearly as simple, will probably need custom magnetics and could very well cost more money to make and will be way out of the range of a DIYer to build.

    I have tested many commercially available switching supplies (certainly not all), designed for many different applications, including many that come with audio devices including some very expensive pro audio equipment and NONE of them bettered the noise levels of this simple linear supply. So while it is certainly possible that a switching supply good do as well or better, it does not seem that this is common in the market place. It is also true that most linear supplies are also very bad as well, and many linear supplies are worse than the switching supplies that people are replacing. I have NEVER said that a linear supply is always better than a switching supply.

    If you would like to test these claims go ahead and build this design (its easy and not very expensive) and compare it to any of your switching designs, paying attention to what is injected back into the AC mains as well as what gets sent to the device, I'd be very interested to see how it stacks up with your switching desings. Oh yeah, and while you're at it try hooking them up to a Touch and see if you hear any differences.

    Here is the schematic of the design mentioned above:

    http://johnswenson1.home.comcast.net/stereo/SB_5V.GIF

    John S.

  10. #70
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    Quote Originally Posted by JohnSwenson View Post

    Here is the schematic of the design mentioned above:

    http://johnswenson1.home.comcast.net/stereo/SB_5V.GIF

    John S.
    Great post

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