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Hi,
My hi-fi sounds great sometimes and not others. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. For example, great one evening but poor the next morning. I leave the electronics on but not playing. Is there a CD that can be played to loosen the system up? I suspect the speakers most. Bass extension is particularly absent at times. Any suggestions as to whether playing a very low frequency sine wave or similar could do the trick? -- TIA, James |
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James Harris wrote:
My hi-fi sounds great sometimes and not others. Most likely causes would be your state of mind and your selection of music to listen to. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. If your system has some technical defect, then warming up could deal with the problem. In general audio systems are up to peak performance within a minute or less of commencment of use. For example, great one evening but poor the next morning. Your system could have a defect that makes it extraordinarly sensitive to operating temperature. I leave the electronics on but not playing. Is there a CD that can be played to loosen the system up? Nothing special should be required. I suspect the speakers most. Bass extension is particularly absent at times. In fact, the cause could be anything else in the system. Any suggestions as to whether playing a very low frequency sine wave or similar could do the trick? Not if your system is in good shape. |
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"Woody" wrote in message ... "Arny Krueger" wrote in message ... James Harris wrote: My hi-fi sounds great sometimes and not others. Most likely causes would be your state of mind and your selection of music to listen to. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. If your system has some technical defect, then warming up could deal with the problem. In general audio systems are up to peak performance within a minute or less of commencment of use. For example, great one evening but poor the next morning. Your system could have a defect that makes it extraordinarly sensitive to operating temperature. More like changes in your hearing. Have you ever noticed that you set your clock-radio in sleep mode and go to sleep listening to the news or whatever fairly quietly, but when it wakes you in the morning it is deafeningly loud? My ears are literally congealed in the morning. As the day wears on, they loosen up. The tissues of the ears live in a world of thick, goopy liquid, the consistency of which varies from hour to hour and day to day. |
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"James Harris" no.email.please wrote in message .. . Hi, My hi-fi sounds great sometimes and not others. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. For example, great one evening but poor the next morning. I leave the electronics on but not playing. Is there a CD that can be played to loosen the system up? I suspect the speakers most. Bass extension is particularly absent at times. Any suggestions as to whether playing a very low frequency sine wave or similar could do the trick? -- TIA, James My hi-fi sounds great late night and during the early hours... single malt may have a lot to do with it ;-) |
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"James Harris" wrote My hi-fi sounds great sometimes and not others. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. For example, great one evening but poor the next morning. I leave the electronics on but not playing. Perhaps you might consider a power line conditioner. These devices reduce RF, EMI and other distortions that leak into your hi-fi gear from AC power lines. While some equipment does not appear (sound wise) to benefit from the device most will, IME. Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Is there a CD that can be played to loosen the system up? I suspect the speakers most. Bass extension is particularly absent at times. Any suggestions as to whether playing a very low frequency sine wave or similar could do the trick? Yes, they are commonly referred to as break-in or system burn-in CD’s. They range from highly specialized (Purest Audio Design System Enhancer, $110) to a single track on a test CD (Cardas/Ayre System Enhancement Disk, $20 or XLO/Reference Recordings Test and Burn-In CD, $27). |
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In article ,
Powell wrote: Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a few chokes and capacitors at most? Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. -- *Eat well, stay fit, die anyway Dave Plowman London SW 12 RIP Acorn |
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"Mike Gilmour" wrote
My hi-fi sounds great late night and during the early hours... single malt may have a lot to do with it ;-) Beer googles for the ears? Martin -- M.A.Poyser Tel.: 07967 110890 Manchester, U.K. http://www.fleetie.demon.co.uk |
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"Dave Plowman" wrote Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a few chokes and capacitors at most? For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. And, some people have bad credit (no plastic) which prevents them from trying a free demo unit in their home setup. Or they don’t know any better. Which are you? For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Consider doing your own home work (empirical experience). |
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In article ,
Powell wrote: For a few chokes and capacitors at most? For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. You must be referring to US stuff. All UK equipment already has an isolating transformer. It would be illegal to sell one without. Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. And, some people have bad credit (no plastic) which prevents them from trying a free demo unit in their home setup. Or they dont know any better. Which are you? I know that you're advocating the spending of money that isn't needed. Just buy decent equipment in the first place. For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Consider doing your own home work (empirical experience). So I take it you just do 'subjective' testing then? Figures. -- *Change is inevitable ... except from vending machines * Dave Plowman London SW 12 RIP Acorn |
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"Powell" wrote in message ... "Dave Plowman" wrote Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a few chokes and capacitors at most? For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. And, some people have bad credit (no plastic) which prevents them from trying a free demo unit in their home setup. Or they don’t know any better. Which are you? For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Consider doing your own home work (empirical experience). Note to UK readers - they're not all locked up yet! |
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"James Harris" no.email.please wrote:
Hi, My hi-fi sounds great sometimes and not others. I am told that it needs an hour's warm-up and this could fit with the times it has sounded good. For example, great one evening but poor the next morning. I leave the electronics on but not playing. Is there a CD that can be played to loosen the system up? I suspect the speakers most. Bass extension is particularly absent at times. Any suggestions as to whether playing a very low frequency sine wave or similar could do the trick? Hi-fi loudspeakers are well known to change after playing some time as the voice coil heats up. If you can hear the difference perhaps it is time to invest in some monitor speakers instead. They tend to use heavier gauge voice coil windings and are better at removing heat from them too. Ian Ian |
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"Dave Plowman" wrote For a few chokes and capacitors at most? For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. You must be referring to US stuff. All UK equipment already has an isolating transformer. It would be illegal to sell one without. Please re-read the above paragraph. It’s “transformers”... that means plural in English. plural adjective 1 more than one in number. 2 Grammar (of a word or form) denoting more than one. Here’s and example of the of the design I use. http://www.audiopower.com/newsite/toc.html Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. And, some people have bad credit (no plastic) which prevents them from trying a free demo unit in their home setup. Or they dont know any better. Which are you? I know that you're advocating the spending of money that isn't needed. How would you know? Just buy decent equipment in the first place. Quack, quack, quack... For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Consider doing your own home work (empirical experience). So I take it you just do 'subjective' testing then? Figures. Sure, you can demo one and find out for yourself.... depending on your financial limitations. For your edification, Mr. Plowman: Nigel's Power Line Conditioner Info Sheet (C) 2000 V 1.15 This document may be copied so long as it is copied in it's entirety, including copyright, and so long as it is not posted to rec.audio.high-end Sections: I. What IS a Power Line Conditioner? II. Why do I NEED/WANT one? III. HTML Links IV. Specific Products & Technology V. Cheap Tweaks for the Dangerously Inclined VI. Closing Comments I. What IS a Power Line Conditioner? ===================================== Before there was such a market for high end tweaks and buzz words in high end audio/video companies like APCC & Tripplite among many others were already making power conditioners for the computer and electronics industry. These devices are still made and they are used to provide voltage regulation for devices like copiers. They used transformers with multiple taps, and as the input voltage surges or sags the relays or transistors in the power conditioner would switch among the different transformer taps. I thought Tice or Audio Power made a similar device, but I seem to be mistaken. Two good sources of non- esoteric power line conditioners are www.furmasound.com and www.equitech.com. Pretty good looking stuff if you have common surge/sagging problems. Today there are many things called a line conditioner, and they are not all the same. In general a power line conditioner can be everything from a power strip with surge protection to larger, beefy boxes that do a variety of things to the incoming AC power. A line conditioner may have some features to do the following: 1. Filter the AC signal so you get closer to an ideal 60 Hz signal. 2. Provide surge protection 3. Provide Under / Over voltage protection (turns off) 4. Provide Under / Over voltage regulation (keeps the output voltage constant) 5. Provide power outage protection (like an Uninterruptable Power Supply) 6. Provide a lower apparent impedance to the source (like PS Audio, Elgar, etc.) Different products work differently, and will have different feature mixes. The heavier, the more you are paying for, so beleive it or not the cost per pound is a good indicator of how much is going into the product, and a good guage of how much you should be paying for it. If you just spent $1,300 on a power strip you can pick up with your pinky, you paid too much. Articles in Hi Fi News and Record Review (a brit mag) in 1998-99 give some insight into building your own. Alas not all filtration is the same. Products which claim to filter RFI/EMI only start to work at around 100 kHz or higher, which is far above human audibility. The theoretically ideal power line filter would filter out all signals below and above 60 Hz. II. Why do I NEED/WANT one? ============================ II.a: NEEDS Unless you suffer from chronic over/under voltages at your house then chances are you don't really need a power conditioner, the system will work reliably without it. You may very well find that surge protection is important to you. Check out the separate "Nigel's Surge Supression Info Sheet". If you're buying some fancy power line conditioner that is supposed to include surge protection, ask them if the equipment has been certified to UL 1449 Second Edition. I have yet to see an audio equipment "Conditioner" manufacturer that claims surge supression publish any sort of UL or CSA listing on their web site, so be careful about relying on them for surge supression. This does not include Monster Cable's strips, they are primarily a surge supressor, with noise filters added, and are in fact UL 1449 certified. II.b: WANTS Audio/videophiles WANT power conditioners because they feel it will improve the quality of their listening or viewing experience. How much of an audible or visible difference a power line conditioner will make in your world depends on the following: 1. The quality of your incoming AC power. 2. The quality of your components power supplies. 3. The resolution of your system (Fix your room acoustics first, then worry about power line issues) 4. The effectiveness & features of the line conditioner. 5. How much noise the line conditioner itself actually creates (a potential problem in a UPS) 6. What frequencies the power conditioner's filtration is effective at. 7. Your gullibility An example of exceptional power supply design is found in much of Krell and Mark Levinson equipment some of which use fully regulated, fully balanced power supplies. This is a rare thing, but any potential benefit from a power conditioner may be a mute point with this equipment. Most amplifiers use unregulated, but highly filtered power supplies, relying on the incoming AC voltage remaining constant, and large capacitors to reduce any noise on the line. II.c: WON'Ts One thing most line conditioners don't do is fix ground loop problems (i.e. a loud 60 Hz hum you hear coming from your speakers), in some cases they can actually make things worse by improving the connection to ground of your equipment. The ideal way to fix a ground loop problem is to use signal level isolation transformers between your system and the source of the problem, which is often the cable TV or a computer connection. Check out: www.jensentransformers.com for a variety of safe solutions. Otherwise, if you want to start a fire or electrocute yourself or your family, use a 2-3 prong adaptor, a.k.a. a cheater plug. There is one exception to this. Power conditioners that provide balanced outputs may reduce ground loop related hums, as well as provide a good lowering of the overall noise floor. Also, power conditioners should not be used to substitute for bad electrical wiring. In some cases a power conditioner may make things worse, drawing more current and stressing the existing wiring. You should NEVER over fuse wiring. III. HTML Links ================ Here is a variety of links to people selling things that go between your equipment and the incoming AC line. www.apcc.com www.audiopower.com www.accuphase.com www.belkin.com www.bestpower.com www.brickwall.com www.elgar.com www.equitech.com www.furmasound.com www.monstercable.com www.psaudio.com www.surgex.com www.ticeaudio.com www.tripplite.com www.vansevers.com You should also check the links from www.stereophile.com which seem to be pretty exhaustive, and mention many more manufacturer links to audio related power line products than I do here. Be warned however that while the list at Stereophile may be more comprehensive than mine, it's less discriminating, and includes some products I feel provide particularly poor return on investment. IV. Products & Technology ========================== Some products merit special attention in my book, for a variety of reasons. Monster Cable ============= Despite having the WORST web site in all of audio regarding technology, with gross technical and gramatical errors, several people have sent me e-mails defending their power strips, claiming they made improvements in picture or video quality. Heck if I know, but you might want to, they're not too expensive. Panamax ======= Panamax gets special because they do have complete A/V surge protection solutions their parts quality does not usually merit what they charge, like $99 for a standard surge strip, and I've read of reliability and warranty problems online, so you should check the archives at www.deja.com. In my opinion APCC, Triplite and Belkin all give you more surge protection/dollar than Panamax. The Panamax DBS+ I have (got a deal on it) has failed to protect my two satelite receivers from wind related static discharge , so I'm not too happy with them these dayas. Brickwall & Zerosurge ===================== Working on a completely different principle of surge protection than MOV based surge protectors are the models from Brick Wall and ZeroSurge. They are basically single pole low pass filters ( a good thing ) for your power lines. The claimed response is -3db at 3 kHz. This effectively limits the maximum Volts/Second. When a surge hits, it becomes a 2nd and 3rd order low pass filter. Surgex also OEM's these devices, or licenses the technology. This low start point for their noise filtration puts them into both my Line Conditioner sheet as well as my Surge Protection sheet. Audo Power & Tice ================= Moving closer to the ideal of a power line conditioner are the ones that use isolation transformers. These have a much better capacity to remove audible power line noise than mere surge strips. Audio Power & Tice have a variety of products you should take a listen to, if you can get past Tice's voodoo web pages (i.e. their Q&A section). Note that not all these products use isolation transformers, so check to be sure what you're getting. Richard Gray's Power Company ============================ Tremendous hype on their web site is parroted almost word for word by dealers and customers. Their web site and "Grey Paper" fails to make any truly technical statements about what the product does and IMHO they offer poor return on investment, considering the parts that actually go into them, and that they sell for around $700. I would encourage people to either spend another $300 for a PS Audio unit, or spend less for something from Furmasound or Equitech, or even getting a power conditioner (not a UPS) from APC or Tripp Lite instead of buying a product from this company. PS Audio ======== New are the Power Plant models from PS Audio. PS Audio has taken the high road, and said electrical bill be damned! We'll get clean power no matter the cost. The Power Plant models are basically power amplifiers that re-create the 115 Volt AC signal at their output. They are perhaps the most ambitious designs I've seen so far and again have some good ideas behind them. Their prices seem very reasonable, considering how much goes into one and the current offerings of power conditioners in the market, and they certainly should be able to meet their twin goals of: Greatly reducing apparent power line impedance - AND - Greatly reducing power line noise and distortion The technology used may very well be the best at doing those two things in combination. Since the Power Plants are essentially class AB amplifiers they are no better than 50% efficient, so expect it to add additional heat and electrical current draw to your electric circuit, which is something to pay attention to if you're close to being overloading it already. On the other hand, using a linear (AB) amplifier stage removes the likelihood of more digital noise being introduced into the 60 Hz waveform it generates. If the PS Audio units don't have enough current capacity, consider the products from Elgar, sweeet....way expensive! If you have money to burn, perhaps you should consider an Elgar as a pre-conditioner, and use a PS Audio unit for your source components only. Other equipment manufacturers should also take note that unlike many sites PS Audio's web site was delightfully free of bovine scatalogical samples. Chang Lightspeed ================ Chang Lightspeed need comments on because of their on-line advertising which demonizes coils & transformers. They're right about small, poorly designed coils actually increasing the power line impedance, however what they fail to note is that by going coilless their conditioners may very well not be able to remove any power line noise within the audible spectrum. This noise is the most important to audiophiles are concerned with as it has the best chance of being propagated through the power supplies of the equipment and finally to our ears. Perhaps this is why their on-line advertising mentions RFI/EMI noise reduction so much, and makes no mention of audio frequency noise reduction. Coil impedance can be overcome by using bigger and better inductors. Does anyone know how much these puppies weigh? I bet you they're lighter and are less expensive to manufacture than comparative products from manufacturers who DO use coils in their designs. Uninterruptable Power Supplies ============================== A UPS is a must for anyone doing serious computer work, but it's benefits for audiophiles will vary. If you're going to try a UPS to improve the sound / picture quality then avoid the standby kind, which have a 2-4 ms lag before they turn on. Get one labeled "line interactive." Because UPS's are designed for computers they usually pay little attention to how much grunge is coming out when they generate the output waveform, which could in turn easily make your system sound worse, not better. The solution is to make sure the output of your UPS is a sine wave, with the lowest possible distortion and noise. So, avoid "stepped aproximation" and look for "pure sinewave" output. Lastly, most UPS have a relatively loose voltage regulation. For example, as the input voltage varies from 90 to 145 volts the UPS will output from 105 to 125 volts. It's a smaller variation than what's coming in, and it's certainly better than any passive conditioners like Audio Power or Tice but it's certainly not the best technology could do if money were no object. Radio Shack =========== Yes, RS can be an audiophiles best friend, especially when he/she is looking for a $20 voltage meter. If you think you have a chronic voltage problem at your home or listening room outlets go get a meter and find out. If it's bad enough, perhaps you should start with a phone call to your electrical company and/or electrician before getting a voltage conditioner. V. Cheap Tweaks for the Dangerously Inclined ============================================= One potential improvement audiophiles can make, fairly easily if they are electronically and dangerously inclined, is to increase the power supply filter capacitance. You can do this both by replacing the current storage capacitors to higher values of capacitance (and equal or better voltages) and also by adding storage capacitance across the maximum + and - voltage rails of the device (make sure the capacitor's voltage rating is greater than the difference between the + and - rails, of course). While we're going there, consider also replacing the filter caps with less inductive versions if possible such as caps from Sanyo or Panasonic (I think, sorry, it's been a while since I was opening data books so check this out yourself) as well as adding polypropelyne or polystyrene capacitors of equal or greater voltage rating in parallel with any upgrades you do. Be careful with how much capacitance you add, adding capacitance increases the turn on (inrush) current and may over-stress the bridge rectifier. Of course, the fix for this is to add a bigger rectifier so you can get more power! (Grunt grunt!) And if you fry your transforer too, well that can be fixed as well! This little tweak alone can greatly increase the S/N ratio of many mass market electronic devices far more than other tweaks, such as new power cables. If you already have a very good power supply it won't matter much as if you didn't (i.e. it will make a bigger difference for mass market Sony or Yamaha than Krell or Mark Levinson). I won't go into any more detail than this, if you have to ask chances are you shouldn't be in there anyway. Oh, yeah, and as always, if you're an idiot and hurt yourself or your equipment don't call me, have your mama call me so I can tell her what a dufus you are. VI. Closing Comments ===================== I don't mean to exclude anyone, so if I missed you or a product you feel deserves special mention send an e-mail to nigel_tufnel@my- deja.com and I'll add it onto this growing and improving list. As always, thoughtful, informative discussions are encouraged, corrections are gladly accepted, and flames may be sent to . It's your ears, eyes and wallet you're trying to please. Advice from anyone is a good way to start but it's your hard earned dollar so you should always be the final judge of a products worth. |
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In article ,
Powell wrote: For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. You must be referring to US stuff. All UK equipment already has an isolating transformer. It would be illegal to sell one without. Please re-read the above paragraph. Its transformers"... that means plural in English. plural adjective 1 more than one in number. 2 Grammar (of a word or form) denoting more than one. So that should read "a better *design* might include having isolating transformers"? Pillock. -- *Corduroy pillows are making headlines. Dave Plowman London SW 12 RIP Acorn |
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On Wed, 14 Apr 2004 17:22:56 +0100, Dave Plowman
wrote: In article , Powell wrote: Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a few chokes and capacitors at most? Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. Quite so. Anything with a CE mark has to adhere to pretty rigid standards for protection against EMI susceptibility. For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Live in an apartment block next to a welding shop? :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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"Stewart Pinkerton" wrote in message ... On Wed, 14 Apr 2004 17:22:56 +0100, Dave Plowman wrote: In article , Powell wrote: Most audio stores will allow you to demo these devices for free so there is no financial risk. The cost of these units start at $200 and run up to $4,000 depending on your needs. For a few chokes and capacitors at most? Some people have more money than sense. Better to buy equipment where the maker has catered for possible mains borne interference. Quite so. Anything with a CE mark has to adhere to pretty rigid standards for protection against EMI susceptibility. For a periodical review of these units check out Stereophile issue Vol. 17 No. 12. Love to know how you arrange for a 'dirty' mains supply to be anything like typical. Live in an apartment block next to a welding shop? :-) -- Stewart Pinkerton | Music is Art - Audio is Engineering Now that would be really unfortunate! What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) Mike |
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In article ,
Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) Here in London, the mains is anything but a pure sine wave - I'd guess because of all the SWPS around. -- *Don't worry; it only seems kinky the first time.* Dave Plowman London SW 12 RIP Acorn |
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"Dave Plowman" wrote For example, better designs might include having isolated transformers, balanced design technology, regeneration of the wave form, outlet isolation/open ground, provide for special need of source/power amps just to prevent electrical grid injection noise. You must be referring to US stuff. All UK equipment already has an isolating transformer. It would be illegal to sell one without. Please re-read the above paragraph. It's "transformers"... that means plural in English. plural adjective 1 more than one in number. 2 Grammar (of a word or form) denoting more than one. So that should read "a better *design* might include having isolating transformers"? I think you need a bigger shovel. |
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Dave Plowman wrote:
In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. -- Nick |
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Nick Gorham wrote:
Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. A typical power supply for audio gear has about 15 VAC on the secondary of the transformer, which includes a lot of power line and trash. The rectifier actually ups the trash content by quite a bit so we're still talking something like 15 volts of power line and other trash at the input to the filter cap(s). Most audio gear filters the mess with a simple capacitive filter, which brings the trash content down to a volt or two. Then, the DC+trash goes through a commodity voltage regulator chip that costs $0.50 or less. The trash is now under 1 millivolt. Total attenuation gets us from 15 volts or more of trash to less than one millivolt or trash or more than 80 dB of attenuation. On top of the good the power supply does, most audio gear has additional power supply rejection built into the circuitry itself. There is another 20 or more dB of trash attenuation there, so total trash attenuation is 100 dB or more. In every case the power line frequency is the predominate source of trash. Most of the means used to deal with the trash are very broad band, so the basic process of keeping power line hum away from the output terminals also nails the other kinds of trash. |
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On Thu, 15 Apr 2004 10:13:39 -0400, "Arny Krueger"
wrote: Nick Gorham wrote: Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. A typical power supply for audio gear has about 15 VAC on the secondary of the transformer, which includes a lot of power line and trash. The rectifier actually ups the trash content by quite a bit so we're still talking something like 15 volts of power line and other trash at the input to the filter cap(s). Most audio gear filters the mess with a simple capacitive filter, which brings the trash content down to a volt or two. Then, the DC+trash goes through a commodity voltage regulator chip that costs $0.50 or less. The trash is now under 1 millivolt. Total attenuation gets us from 15 volts or more of trash to less than one millivolt or trash or more than 80 dB of attenuation. On top of the good the power supply does, most audio gear has additional power supply rejection built into the circuitry itself. There is another 20 or more dB of trash attenuation there, so total trash attenuation is 100 dB or more. In every case the power line frequency is the predominate source of trash. Most of the means used to deal with the trash are very broad band, so the basic process of keeping power line hum away from the output terminals also nails the other kinds of trash. Nice explanation. Keep it up. |
System warm-up
Arny Krueger wrote:
Nick Gorham wrote: Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. Agreed, I was just pointing out that transformers on their own did little, and as you say a cap input PSU with cheap rectifiers may well create move crud than gets in from he mains. Not sure however just how many power output stages are driven from a regulated supply, I would have expected the pre stages to be fed from a regulated supply. -- Nick |
System warm-up
Nick Gorham wrote:
Arny Krueger wrote: Nick Gorham wrote: Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. Agreed, I was just pointing out that transformers on their own did little, and as you say a cap input PSU with cheap rectifiers may well create move crud than gets in from he mains. It's almost a certainty! Basically the rectifiers take a sine wave with a few percent crud or less, and turn it into something that has tens of percent of THD when meausred. Not sure however just how many power output stages are driven from a regulated supply, Typically there is no formal regulation in the power supply related to the feed for the output stages.. Under full load, there are usually several volts of AC across the power supply caps. It's easy enough to measure in most power amps. The first line of defense is the power supply noise rejection of the power amp itself. That that this is sufficient to build power amps with all noise and distortion 90 or more dB down should be noted. I would have expected the pre stages to be fed from a regulated supply. That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everthing runs off the same voltage source as the output devices. BTW, RIP Doub Self's "Amplifier Institute". A sad loss. |
System warm-up
In article , Arny Krueger
writes Nick Gorham wrote: Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. A typical power supply for audio gear has about 15 VAC on the secondary of the transformer, which includes a lot of power line and trash. The rectifier actually ups the trash content by quite a bit so we're still talking something like 15 volts of power line and other trash at the input to the filter cap(s). Most audio gear filters the mess with a simple capacitive filter, which brings the trash content down to a volt or two. Then, the DC+trash goes through a commodity voltage regulator chip that costs $0.50 or less. The trash is now under 1 millivolt. Total attenuation gets us from 15 volts or more of trash to less than one millivolt or trash or more than 80 dB of attenuation. On top of the good the power supply does, most audio gear has additional power supply rejection built into the circuitry itself. There is another 20 or more dB of trash attenuation there, so total trash attenuation is 100 dB or more. In every case the power line frequency is the predominate source of trash. Most of the means used to deal with the trash are very broad band, so the basic process of keeping power line hum away from the output terminals also nails the other kinds of trash. 15 volts seems a tad low when I last looked the Audiolab amps had about twice that. Not that I can say I've ever had a problem with power line supplies.... -- Tony Sayer |
System warm-up
"Arny Krueger" wrote in message ... Nick Gorham wrote: Dave Plowman wrote: In article , Mike Gilmour wrote: What constitutes 'dirty' mains anyway? What about utilities signalling systems, mains borne baby alarms, intercom systems etc, not as invasive as Stewarts suggestion of a neighbouring welding shop but pollution never the less. I'm way out the in country but 'scoping my mains showed evenly spaced spikes... tracked down to an electric fence a third of a mile away. ;-) A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. The transformer is the secondary or tertiary line of defense. The power supply itself carries the major burden. A typical power supply for audio gear has about 15 VAC on the secondary of the transformer, which includes a lot of power line and trash. The rectifier actually ups the trash content by quite a bit so we're still talking something like 15 volts of power line and other trash at the input to the filter cap(s). Most audio gear filters the mess with a simple capacitive filter, which brings the trash content down to a volt or two. Then, the DC+trash goes through a commodity voltage regulator chip that costs $0.50 or less. The trash is now under 1 millivolt. Total attenuation gets us from 15 volts or more of trash to less than one millivolt or trash or more than 80 dB of attenuation. On top of the good the power supply does, most audio gear has additional power supply rejection built into the circuitry itself. There is another 20 or more dB of trash attenuation there, so total trash attenuation is 100 dB or more. In every case the power line frequency is the predominate source of trash. Most of the means used to deal with the trash are very broad band, so the basic process of keeping power line hum away from the output terminals also nails the other kinds of trash. Replacing rectifiers with Schottky barrier ones that supposedly don't generate reverse recovery transients from stored charge & minority carrier injection - does that change the situation much even if you don't use a regulator chip? |
System warm-up
On Thu, 15 Apr 2004 12:36:58 -0400, "Arny Krueger"
wrote: That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everthing runs off the same voltage source as the output devices. If by 'extra filtering' you're talking about C9 and 1, then it's not really very useful--those capacitors will follow the main smoothing capacitors and discharge through the output stage. A schottky diode to separate the main supply capacitors from local smoothing on an isolated small signal supply would work wonders to reject rail sags and grunge caused by the output stage. -- td |
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The Devil wrote:
On Thu, 15 Apr 2004 12:36:58 -0400, "Arny Krueger" wrote: That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everthing runs off the same voltage source as the output devices. If by 'extra filtering' you're talking about C9 and 1, then it's not really very useful- I'm not talking about that at all. Sorry for any possible lack of clarity. I intended this to be an example of a power amp where everything runs off the same basic voltage source as the output devices. In fact, that's what I said - " Everything runs off the same voltage source as the output devices." -those capacitors will follow the main smoothing capacitors and discharge through the output stage. Agreed. A schottky diode to separate the main supply capacitors from local smoothing on an isolated small signal supply would work wonders to reject rail sags and grunge caused by the output stage. As a rule, tweaks such as this just don't have any practical technical advantages. Wire 'em in and there's usually no visible effect on the display of residuals from distortion analyzer. |
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In article ,
Nick Gorham wrote: A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. I must admit to not having tested a toroidal - it's ages since I looked at this. But if it's letting through significant amounts of 'interference' that the normal smoothing and decoupling doesn't stop within the audio band, I'd assume you'd hear it. -- *The e-mail of the species is more deadly than the mail * Dave Plowman London SW 12 RIP Acorn |
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Arny Krueger wrote:
BTW, RIP Doub Self's "Amplifier Institute". A sad loss. Ouch. What happened. Any idea why it went? We have already lost Linsley Hood, Doug Self hasn't gone too has he? Ian |
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In message , Dave Plowman
writes In article , Nick Gorham wrote: A well designed mains transformer will attenuate anything outside about 50 Hz by a considerable amount - if it didn't, decent audio transformers wouldn't be so expensive. ;-) I have seen normal mains torroids used as valve output transformers. Thay do a adiquate job, so they must let through (in that situation anyway) 50hz. I must admit to not having tested a toroidal - it's ages since I looked at this. But if it's letting through significant amounts of 'interference' that the normal smoothing and decoupling doesn't stop within the audio band, I'd assume you'd hear it. Don't forget that the toroids used in audio amps tend not to have inter-winding screens. The inter-winding capacitance also tends to be higher than that of E-I core transformers. They therefore let through pretty much all the common-mode noise on the mains. I know that neutral is bonded to ground at the sub-station, but in many places the common-mode on the mains is horrible (not helped by all the CM crap coming out of SMPSUs, even those with power-factor correction). A good common-mode filter will clean things up a lot. -- Chris Morriss |
System warm-up
"S888Wheel" wrote in message
... snip My hi-fi sounds great sometimes and not others. snip Maybe you could give us the specifics on your system. Nad C541i as transport, Meridian 203 DAC, Rotel RA-02 amp, Dynaudio Audience 62 floorstand speakers Chord Optichord digital link, Audioquest Python interconnects, Atlas 2.0 speaker cable, Atacama Equinox rack The dealer advised a 30 to 60 minute warmup before each listening session - which is a pain and I'm not convinced that the improved sound quality follows such a warmup. The improvement seems random - and unexpected. Maybe mains problems? The sonic difference to the bass is quite clear. Forgive the adjectives but when it's not working well the sound is OK but 'thin' and lacks energy. When it works well the bass is rich and the sound fuller and more musical at the same volume. It even sounds good with the volume lower. The Audioquest Pythons were the last addition. I wasn't happy with the system - it didn't have the clarity - until they were added to replace Atlas Voyagers. Does the kit list above give any clues as to why the sound would change? (BTW, thanks too for your suggestions on test CDs.) |
System warm-up
On Thu, 15 Apr 2004 14:03:06 -0400, "Arny Krueger"
wrote: That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everthing runs off the same voltage source as the output devices. If by 'extra filtering' you're talking about C9 and 1, then it's not really very useful- I'm not talking about that at all. Sorry for any possible lack of clarity. I intended this to be an example of a power amp where everything runs off the same basic voltage source as the output devices. No, I don't understand. You said 'In other cases there is some built-in extra filtering,' and you provided a link to an amp that has local smoothing provided by capacitors 8 and 1. Now you say you weren't 'talking about that at all'. As a rule, tweaks such as this just don't have any practical technical advantages. And of course we all know that pretty much every nominally competent amp (in terms of measurement) sounds just like any other of same . . . -- td |
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The Devil wrote:
On Thu, 15 Apr 2004 14:03:06 -0400, "Arny Krueger" wrote: That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everything runs off the same voltage source as the output devices. If by 'extra filtering' you're talking about C9 and 1, then it's not really very useful- I'm not talking about that at all. Sorry for any possible lack of clarity. I intended this to be an example of a power amp where everything runs off the same basic voltage source as the output devices. No, I don't understand. What's unclear about the explanation I just gave you? You said 'In other cases there is some built-in extra filtering,' and you provided a link to an amp that has local smoothing provided by capacitors 8 and 1. Now you say you weren't 'talking about that at all'. There is he slight matter of the sentence: "Everything runs off the same voltage source as the output devices." Same paragraph as the link. As a rule, tweaks such as this just don't have any practical technical advantages. And of course we all know that pretty much every nominally competent amp (in terms of measurement) sounds just like any other of same . . . You know that, eh? I perceive a change of philosophy on your part. When did this happen? |
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On Thu, 15 Apr 2004 17:36:25 -0400, "Arny Krueger"
wrote: That is usually the case. The early stages of the main part of the power amp circuit often run off the same source as the output devices. In other cases there is some built-in extra filtering. http://www.citycom.gr/electronics/pr...l/100ampl5.gif shows a fairly typical design. Everything runs off the same voltage source as the output devices. If by 'extra filtering' you're talking about C9 and 1, then it's not really very useful- I'm not talking about that at all. Sorry for any possible lack of clarity. I intended this to be an example of a power amp where everything runs off the same basic voltage source as the output devices. No, I don't understand. What's unclear about the explanation I just gave you? See below. You said 'In other cases there is some built-in extra filtering,' and you provided a link to an amp that has local smoothing provided by capacitors 8 and 1. Now you say you weren't 'talking about that at all'. There is he slight matter of the sentence: "Everything runs off the same voltage source as the output devices." Same paragraph as the link. Yes. But you specifically mentioned 'extra filtering' for the small signal stages ('early', in your technical parlance) of an amp, then posted a link to an amp which does not posses that filtering. As a rule, tweaks such as this just don't have any practical technical advantages. And of course we all know that pretty much every nominally competent amp (in terms of measurement) sounds just like any other of same . . . You know that, eh? I perceive a change of philosophy on your part. When did this happen? It didn't. I know it's bull****. -- td |
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James Harris wrote:
"S888Wheel" wrote in message ... snip My hi-fi sounds great sometimes and not others. snip Maybe you could give us the specifics on your system. Nad C541i as transport, Meridian 203 DAC, Rotel RA-02 amp, Dynaudio Audience 62 floorstand speakers James, I am curious. The Meridian DAC is at least 12 years old. I would have thought that the newer Burr Brown DACs in the NAD would measure better and produce "better" sound than the older Philips DAC in the Meridian (is it multibit or bitstream?) |
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On Thu, 15 Apr 2004 22:58:23 +0100, The Devil wrote:
On Thu, 15 Apr 2004 17:36:25 -0400, "Arny Krueger" wrote: And of course we all know that pretty much every nominally competent amp (in terms of measurement) sounds just like any other of same . . . You know that, eh? I perceive a change of philosophy on your part. When did this happen? It didn't. I know it's bull****. Oh, really? I'm still up for it if you are, with your trusty Quads........... -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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On Fri, 16 Apr 2004 06:57:21 +0000 (UTC), Stewart Pinkerton
wrote: Oh, really? I'm still up for it if you are, with your trusty Quads........... Actually, I think the 989s are less sensitive to power amps than most other speakers. ATM, I'm driving them with a cheapy Rotel (PSU Black Gated--more snake oil :-)) and they sound very . . . Quadish. You've already found differences among power amps that measure well. No need to re-prove what you already know, Stewart. :-) -- td |
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In article , James Harris
no.email.please wrote: "S888Wheel" wrote in message ... snip My hi-fi sounds great sometimes and not others. snip Maybe you could give us the specifics on your system. Nad C541i as transport, Meridian 203 DAC, Rotel RA-02 amp, Dynaudio Audience 62 floorstand speakers Chord Optichord digital link, Audioquest Python interconnects, Atlas 2.0 speaker cable, Atacama Equinox rack Since this is being cross-posted to 'opinion'... :-) FWIW I use two main systems. One now uses a pair of ESL63's and a Meridian 263 DAC. The other now uses a pair of ESL988's and a Meridian 563 DAC. (You may spot a pattern, here... ;- ) In each case I tend to switch the speaker energisation and DAC power on in the morning, and off at the end of the evening. I have a slight impression that the speakers (and maybe the DACs) benefit from this. However the changes are so small I am not at all sure of this. I general I don't bother switching on amplifiers more than a few mins before use. So far as I can tell, letting my amplifiers warm up has no effect that seems audible to me. The dealer advised a 30 to 60 minute warmup before each listening session - which is a pain and I'm not convinced that the improved sound quality follows such a warmup. The improvement seems random - and unexpected. Maybe mains problems? The sonic difference to the bass is quite clear. Forgive the adjectives but when it's not working well the sound is OK but 'thin' and lacks energy. When it works well the bass is rich and the sound fuller and more musical at the same volume. It even sounds good with the volume lower. The Audioquest Pythons were the last addition. I wasn't happy with the system - it didn't have the clarity - until they were added to replace Atlas Voyagers. Does the kit list above give any clues as to why the sound would change? (BTW, thanks too for your suggestions on test CDs.) I also hear (apparent) changes from time to time in terms of relative bass level, etc. However it does not seem to correlate with anything so I suspect it is just my perceptions altering as a result of various 'extraneous' influences... Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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In article ,
Tat Chan wrote: James Harris wrote: Nad C541i as transport, Meridian 203 DAC, Rotel RA-02 amp, Dynaudio Audience 62 floorstand speakers James, I am curious. The Meridian DAC is at least 12 years old. I would have thought that the newer Burr Brown DACs in the NAD would measure better and produce "better" sound than the older Philips DAC in the Meridian (is it multibit or bitstream?) I doubt that this is simply a matter of choice of DAC chip. Other influences will include the PSU, buffering, differences in filtering, etc. FWIW I remain a fan of the Meridian 263 and 563, (as well as the Quad 67) despite them being 'out of favour' for a while for technical reasons. Maybe they'll become popular again if SACD really takes hold. A situation with a certain wry irony for Bob Stuart if it occurs... ;- Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
System warm-up
In article , Mike Gilmour
wrote: Replacing rectifiers with Schottky barrier ones that supposedly don't generate reverse recovery transients from stored charge & minority carrier injection - does that change the situation much even if you don't use a regulator chip? When designing/building amps myself I just used to shove small caps in parallel with each bridge diode to eat the 'snap'... However for me the main line of defence was a design that inherently had a good amount of rail ripple/noise/interference rejection, and good earthing. This means that even of HF rubbish gets through the PSU them amp will largely ignore it. Slainte, Jim -- Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html |
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