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#1
Posted to rec.audio.pro
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Dirty Power
Can anyone help me understand - or point me to some good resources -
why the AC in Brooklyn, NY adds so much noise to guitar amplifiers? I have six or seven different tube and solid state guitar amps that I use in my apartment, recording studio, and at a rehearsal studio - all three locations are in the same neighborhood. The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. It's hard to describe these things, obviously, but it's basically sort of mid frequency hiss, with an intermittent paper clips being flushed down the toilet sound. There are some day when I don't experience the noise, but it is otherwise consistent between amps and locations - and it happens whether or not an instrument is plugged in. This is why I believe it must be related to the power source. Any ideas? Are there "power conditioners" that can alleviate this problem? Thanks. Steve |
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#2
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Dirty Power
Noise in the mains is caused by all sorts of interference and can affect the
quality of the sound produced by any hardware. I've seen many different mains conditioners reviewed on Sound on Sound's website although I can't recall any manufacturers off the top of my head. Search in Sound on Sound's archives and you'll find some I'm sure. |
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#4
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Dirty Power
Thanks for the tip.
So I saw that the box you recommended - the Furman IT-20 - is around $1700 street price. So I went to Guitar Center and bought a Furman Power Factor Pro conditioner hoping that it would solve the problem. Unfortunately, it did not resolve the issue at all on any of the amplifiers on which I tried it. Does anyone know of anything like the IT-20 that I could try that's not so expensive? Thanks, Steve Romeo Rondeau wrote: wrote: Can anyone help me understand - or point me to some good resources - why the AC in Brooklyn, NY adds so much noise to guitar amplifiers? I have six or seven different tube and solid state guitar amps that I use in my apartment, recording studio, and at a rehearsal studio - all three locations are in the same neighborhood. The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. It's hard to describe these things, obviously, but it's basically sort of mid frequency hiss, with an intermittent paper clips being flushed down the toilet sound. There are some day when I don't experience the noise, but it is otherwise consistent between amps and locations - and it happens whether or not an instrument is plugged in. This is why I believe it must be related to the power source. Any ideas? Are there "power conditioners" that can alleviate this problem? Thanks. Steve You might try a balanced power system. Basically it's running your ac power through a transformer. Instead of the device getting +120 volts hot and 0 volts neutral with the ground at 0 volts, it gets +60 volts hot and -60 volts neutral with the ground at 0 volts. The AC devices still see 120 across the hot and neutral, so they don't care. The good thing is that noise that exists from the ground gets cancelled out in both rails, just like a microphone cable or a humbucking pickup. It may fix your problem, it may not but it sure makes everything quieter in the studio. Furman makes one, here's a link: http://www.furmansound.com/products/pro/blncd/it-20.php There are other ones out there, this is the one I have experience with. Hope it helps! |
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#6
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Dirty Power
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#7
Posted to rec.audio.pro
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Dirty Power
Soundhaspriority wrote: Permit me to doubt, but the noise is more likely internal to the amps. If these are tube guitar amps, they contain foil capacitors that become "unsealed" with age, and are self-repairing. While it's certainly possible that all of his amplifiers need repair, my initial reading was that they worked before he moved to Brooklyn. But I may have read too much into it. My answer stands - there's nothing we can do other than guess. He has the amplifiers, he has to do the analysis. He may not be able to do that. |
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#8
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Dirty Power
wrote Are there "power conditioners" that can alleviate this problem? Power conditioners to fall into four different classes: 1. General filtering 2. Specialized filtering: analog, digital, power amp 3. Specialized filtering with isolated transformers 4. Power regeneration FYI... Nigel's Power Line Conditioner Info Sheet ©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 source 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. Happy Listening, Nigel |
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#9
Posted to rec.audio.pro
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Dirty Power
On Sun, 1 Oct 2006 08:41:52 -0400, "Powell"
wrote: Nigel's Power Line Conditioner Info Sheet ©2000 Note that this is written from the angle of debunking audiophile gadgets. Balanced power supplies for studio equipment do not (necessarily) deserve this :-) |
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#10
Posted to rec.audio.pro
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Dirty Power
"Powell" writes:
wrote =big snip = Uninterruptable Power Supplies ============================== = little snip = 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 Very true. 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. Also known as "double conversion" from the manufacturers that do "pure sine" correctly. 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 Generally not the case with a double-conversion UPS. These take incoming AC, convert it to DC, then feed a *good* inverter to generate new, pure AC. Somewhere along that DC line they also have a battery waiting to supply DC to the inverter should the incoming AC go away. This means you can have really awful incoming power (sags, noise, harmonic issues, etc) and you get squeaky clean "new" AC on the other side -- and this is continuous. It also means a very short AC path between your gear and the "power plant" (the plug on the back of the UPS), which can have a number of advantages. Heavy, expensive, and typically not found at your local computer store (special ordered from industrial supply houses) -- but from more than one experience with iffy location power (especially when a PA company is involved), I'd say worth it. Frank Stearns Mobile Audio -- |
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#11
Posted to rec.audio.pro
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Dirty Power
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#12
Posted to rec.audio.pro
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Dirty Power
Romeo Rondeau wrote:
wrote: Thanks for the tip. So I saw that the box you recommended - the Furman IT-20 - is around $1700 street price. So I went to Guitar Center and bought a Furman Power Factor Pro conditioner hoping that it would solve the problem. Unfortunately, it did not resolve the issue at all on any of the amplifiers on which I tried it. Does anyone know of anything like the IT-20 that I could try that's not so expensive? I think that $1700 for something that makes this much of an impact on the noise levels in a studio a bargain, but I also understand that everyone's on some kind of budget. You could build one if you can get the parts. I'll bet Scott Dorsey would have some good advice here. I think that balanced power is mostly a scam and only solves one specific problem: chassis leakage inside the equipment. On the other hand, with a balanced power system you get the other benefits of having an isolation transformer, like for example some effective low-pass filtering. Maybe that is what you need. Maybe it isn't. Find the source of the problem and address it before you spend any money on anything. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#13
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Dirty Power
Romeo Rondeau wrote:
wrote: Can anyone help me understand - or point me to some good resources - why the AC in Brooklyn, NY adds so much noise to guitar amplifiers? I have six or seven different tube and solid state guitar amps that I use in my apartment, recording studio, and at a rehearsal studio - all three locations are in the same neighborhood. The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. It's hard to describe these things, obviously, but it's basically sort of mid frequency hiss, with an intermittent paper clips being flushed down the toilet sound. There are some day when I don't experience the noise, but it is otherwise consistent between amps and locations - and it happens whether or not an instrument is plugged in. This is why I believe it must be related to the power source. Any ideas? Are there "power conditioners" that can alleviate this problem? Thanks. Steve You might try a balanced power system. Basically it's running your ac power through a transformer. Instead of the device getting +120 volts hot and 0 volts neutral with the ground at 0 volts, it gets +60 volts hot and -60 volts neutral with the ground at 0 volts. The AC devices still see 120 across the hot and neutral, so they don't care. The good thing is that noise that exists from the ground gets cancelled out in both rails, just like a microphone cable or a humbucking pickup. It may fix your problem, it may not but it sure makes everything quieter in the studio. Furman makes one, here's a link: http://www.furmansound.com/products/pro/blncd/it-20.php There are other ones out there, this is the one I have experience with. Hope it helps! balanced power systems are mostly snake oil. You need to go figure out what the real problem is. Unless you have boatloads of money to spend, in which case, moving to a newer apartment building that is further away from industrial parks and transmitters would be easier. Is the noise exactly the same at all times of the day and night and weekends? Are you near any TV or Radio transmitter antennas? Industrial parks? electrical substations? Have the amps been modified in any way from factory specs? Are they in good repair? Have you had a recent hearing examination? Can other folks identify the noise without prompting from you? Do any control manipulations, swapping out, adding or removing connector cables, guitars, stomp boxes, DIs, or whatever make changes in the noise? --Dale |
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#14
Posted to rec.audio.pro
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Dirty Power
The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. It's hard to describe these things, obviously, but it's basically sort of mid frequency hiss, with an intermittent paper clips being flushed down the toilet sound. There are some day when I don't experience the noise, but it is otherwise consistent between amps and locations - and it happens whether or not an instrument is plugged in. This is why I believe it must be related to the power source. Any ideas? Bizarre! Could you make a very short wav file of it and post it? It's probably radio frequency interference of some kind. With all the digital modulation in use now, like with cell phones and trunked radio sites, which often have very many transmitters in relatively constant use, the chance of picking up some RFI in a densely populated area is pretty high. Another really annoying, perhaps even more pervasive radio frequency interference one will encounter is from TV sets and any old CRT. With flat screens becoming more ubiquitous and replacing CRTs, that horrible manner of interference is on the wane, but it's almost everywhere and still a big problem, and... you got it, it propagates quite nicely over power lines. So to answer your question regarding getting rid of this interference in your guitar amps... I'd bone up on how to protect your high impedance inputs in high gain preamps from RFI. Good shielding practices are so important but almost impossible with electric guitars, which are like wonderful antennas, even though they're not supposed to be, so you have to figure out ways to deal with it. The two most effective that I know of besides shielding are capacitor shunts, that is shorting the RF signal to ground by putting a very small value capacitor across the input of a high Z preamp, and the other is to use in-line inductors or chokes. Some chokes can consist merely of a ferrite bead with the input wire strung through it. Just as a place to start, take a look at some schematics for mic preamps or guitar preamps and see what other successful designs use. Sometimes I see like 100 pico-Ferad capacitors across mic inputs for example. Anyway, I'd investigate those things on the internet and see if you can come up with more detail and a better general understanding of the subject before you proceed. Since a shunt capacitor is a low pass filter, you don't want to use too big of a value for an RF shunt, so as to prevent rolling off high frequency audio, though you shouldn't need anything bigger than 100pF in my estimation. There are all kinds of places RFI can enter a circuit, so RFI filtering on the AC power strip would be a good thing to try too. Good luck! :-) Skler |
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#15
Posted to rec.audio.pro
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Dirty Power
I think that $1700 for something that makes this much of an impact on the noise levels in a studio a bargain, but I also understand that everyone's on some kind of budget. You could build one if you can get the parts. I'll bet Scott Dorsey would have some good advice here. A handful of RF shunt capacitors and in line RFI chokes would cost under a dollar or perhaps up to a few dollars, so I'd say that kind of price is more than ridiculous, it's dishonest. The same holds true in general for filtered and protected outlet strips costing 30 or 40 bucks on upward, simply containing a few MOVs and chokes for example. There are some more sophisticated filter designs that are really nice, especially in the context of Uninterruptible Power Supplies, employing carefully designed switched power supplies or sometimes even high voltage filter capacitors, but the highly cost of those is quite legitimate, not such a scam as the typical filtered and protected AC power strip. Skler |
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#16
Posted to rec.audio.pro
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Dirty Power
It's probably radio frequency interference of some kind. With all the
digital modulation in use now, like with cell phones and trunked radio sites, which often have very many transmitters in relatively constant use, the chance of picking up some RFI in a densely populated area is pretty high. Another really annoying, perhaps even more pervasive radio frequency interference one will encounter is from TV sets and any old CRT. With flat screens becoming more ubiquitous and replacing CRTs, that horrible manner of interference is on the wane, but it's almost everywhere and still a big problem, and... you got it, it propagates quite nicely over power lines. So to answer your question regarding getting rid of this interference in your guitar amps... I'd bone up on how to protect your high impedance inputs in snip PS RFI or EMI can also, though not as often, enter an amplifier through the speaker output leads! It can enter speaker leads, get into a driver or pre-driver stage or even float on top of an ungrounded circuit chassis/common and then get into an earlier stage and become amplified along with the audio signal. So... if shunt or choke filtering on inputs and AC mains fails to eliminate your problem, you might also look into dealing with output shunting with very small value capacitors. I'd consider this approach as a last resort though. Skler |
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#17
Posted to rec.audio.pro
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Dirty Power
Skler wrote:
I think that $1700 for something that makes this much of an impact on the noise levels in a studio a bargain, but I also understand that everyone's on some kind of budget. You could build one if you can get the parts. I'll bet Scott Dorsey would have some good advice here. The box he is talking about is a "balanced power unit" basically an isolation transformer with a grounded center tap. It's expensive because an isolation transformer capable of handling a lot of current is big and has a lot of iron and copper in it. A handful of RF shunt capacitors and in line RFI chokes would cost under a dollar or perhaps up to a few dollars, so I'd say that kind of price is more than ridiculous, it's dishonest. The problem is that real RFI chokes also have a lot of iron and copper in them and are expensive. You want to run 20 amps through a pi filter tuned to 60 Hz, you get a transformer that weighs twenty pounds or so. That is why real power filters (as opposed to isolation transformers or cheez-whiz RF filters) are heavy and expensive. The same holds true in general for filtered and protected outlet strips costing 30 or 40 bucks on upward, simply containing a few MOVs and chokes for example. There are some more sophisticated filter designs that are really nice, especially in the context of Uninterruptible Power Supplies, employing carefully designed switched power supplies or sometimes even high voltage filter capacitors, but the highly cost of those is quite legitimate, not such a scam as the typical filtered and protected AC power strip. Most of these filtered strips don't have much filtering, and have little common mode chokes tuned way up high. Useful for actual RF at low levels, but totally useless for stuff below the KHz region. You want to actually clean up the waveform, you need a lot of iron. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#18
Posted to rec.audio.pro
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Dirty Power
On 30 Sep 2006 10:58:51 -0700, "
wrote: Are there "power conditioners" that can alleviate this problem? Yes, and I've been using one since 1994 in Midtown. They work; and it's advisable to not get too caught up in the smoke and mirror aspect these. This article may be a good starting point: http://www.stereophile.com/powerlineaccessories/499api/ A_C |
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#19
Posted to rec.audio.pro
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Dirty Power
balanced power systems are mostly snake oil. You need to go figure out what the real problem is. Unless you have boatloads of money to spend, in which case, moving to a newer apartment building that is further away from industrial parks and transmitters would be easier. Balanced power may not help in all applications, true. Calling it snake oil is horse****. I've seen the improvement first hand. 'Nuff said. Not only did our noise figures improve substantially, but we also lost all of our little clocking abnormalities. We had some pretty dirty power before we started and the addition of the Furman cleaned it all up quite nicely. You're saying that moving to a different location is "easier?", you must be completely off your rocker! |
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#20
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Dirty Power
Romeo Rondeau wrote:
Balanced power may not help in all applications, true. Calling it snake oil is horse****. I've seen the improvement first hand. 'Nuff said. Not only did our noise figures improve substantially, but we also lost all of our little clocking abnormalities. We had some pretty dirty power before we started and the addition of the Furman cleaned it all up quite nicely. You're saying that moving to a different location is "easier?", you must be completely off your rocker! The thing is, the balanced power boxes ALSO provide low pass filtering and ground isolation. Those two things provide most of the benefit. The actual balancing isn't of much benefit. It reduces noise due to chassis leakage issues, though. But your noise figures probably improved for reasons not related to the balancing itself. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#21
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Dirty Power
Try a big fat isolated transformer, like a 5kVA Topaz. The can be had
through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! |
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#22
Posted to rec.audio.pro
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Dirty Power
Scott Dorsey wrote:
Romeo Rondeau wrote: Balanced power may not help in all applications, true. Calling it snake oil is horse****. I've seen the improvement first hand. 'Nuff said. Not only did our noise figures improve substantially, but we also lost all of our little clocking abnormalities. We had some pretty dirty power before we started and the addition of the Furman cleaned it all up quite nicely. You're saying that moving to a different location is "easier?", you must be completely off your rocker! The thing is, the balanced power boxes ALSO provide low pass filtering and ground isolation. Those two things provide most of the benefit. The actual balancing isn't of much benefit. It reduces noise due to chassis leakage issues, though. But your noise figures probably improved for reasons not related to the balancing itself. --scott Digital devices dump a lot of **** through the ground plane. In a studio where there are a lot of digital devices it makes a difference, although you may have a point about how much it helped. It really comes down to what you've got stuffed into your racks and how nasty your power is. The real problem is that your electric company only cares that you HAVE power, not that it's in any kind of condition when it gets to you. |
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#23
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Dirty Power
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#24
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Dirty Power
In article .com,
"ABacon" wrote: Try a big fat isolated transformer, like a 5kVA Topaz. The can be had through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! Keep an eye on ebay, you can buy one waaay cheap. David Correia www.Celebrationsound.com |
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#25
Posted to rec.audio.pro
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Dirty Power
wrote:
(Scott Dorsey) writes: Most of these filtered strips don't have much filtering, and have little common mode chokes tuned way up high. Useful for actual RF at low levels, but totally useless for stuff below the KHz region. You want to actually clean up the waveform, you need a lot of iron. Amen! See if you can find anyone who has an old black DEC power controller in their junk collection. Might be hard to find nowdays though. It will also probably be 3 phase, but dont worry about that. There are lots of them out there. In the US, try C&H Surplus Sales in Pasadena, CA. They usually have a bunch of real power conditioners for a couple hundred bucks or so. Be prepared to pay freight charges. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#26
Posted to rec.audio.pro
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Dirty Power
The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. This seems really fishy to me, are you positive this is the case? Correct me if I'm wrong, but doesn't this mean the noise source is post gain stage? How could the noise source effect the signal post-gain but not before it (I can think of a few bad PCB grounding practices that might do this, but for them to be replicated across 7 amps would be very unlikely) -- Posted via a free Usenet account from http://www.teranews.com |
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#27
Posted to rec.audio.pro
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Dirty Power
In article , (Scott Dorsey) wrote:
wrote: (Scott Dorsey) writes: Most of these filtered strips don't have much filtering, and have little common mode chokes tuned way up high. Useful for actual RF at low levels, but totally useless for stuff below the KHz region. You want to actually clean up the waveform, you need a lot of iron. Amen! See if you can find anyone who has an old black DEC power controller in their junk collection. Might be hard to find nowdays though. It will also probably be 3 phase, but dont worry about that. There are lots of them out there. In the US, try C&H Surplus Sales in Pasadena, CA. They usually have a bunch of real power conditioners for a couple hundred bucks or so. Be prepared to pay freight charges. --scott I don't imagine I know what they were. I worked there in 1969. I have used one of their old transformers in a power supply I built. The ferro resonant transformer keept a fairly constant voltage as used on the old Dec unregulated power supplies. We used to do power checks to see under what power conditions the computers and peripherals would continue to opperate and not bomb out. I have had this supplier on my list for many years. http://www.keyways.com/ greg |
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#28
Posted to rec.audio.pro
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Dirty Power
The box he is talking about is a "balanced power unit" basically an isolation transformer with a grounded center tap. It's expensive because an isolation transformer capable of handling a lot of current is big and has a lot of iron and copper in it. Yeah, isolation transformers are great! I've never known anyone to power their whole studio set up on one. I one at work when I'm repairing stuff sometimes, but it doesn't have to handle near as much power. The problem is that real RFI chokes also have a lot of iron and copper in them and are expensive. You want to run 20 amps through a pi filter tuned to 60 Hz, you get a transformer that weighs twenty pounds or so. That is why real power filters (as opposed to isolation transformers or cheez-whiz RF filters) are heavy and expensive. That's true, if you're talking about chokes for power filtering. High impedance and/or high gain inputs are often a problem in terms of picking up EMI and if one is working in an area with really bad EMI, it could get into any guitar amp. I hear TV horizontal oscillators on every guitar amp I've ever hooked up at my house and the EMI isn't getting in through the power line or power supply, but through the amp's input. I suppose an easy test would be to put your amp on a UPS and see if the noise goes away, but then some UPS's have noise problems too! :-) Most of these filtered strips don't have much filtering, and have little common mode chokes tuned way up high. Useful for actual RF at low levels, but totally useless for stuff below the KHz region. You want to actually clean up the waveform, you need a lot of iron. Good advice! I hope the original poster can solve his noise problem. :-) Skler |
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#29
Posted to rec.audio.pro
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Dirty Power
The noise is consistent on all amps and does not increase or decrease in volume when the amps are turned up or down. Maybe it's getting in on the output & getting amplified in the output stage. I've definitely seen / heard this before. Worst case scenario is if you're close to an AM broadcast antenna site. Rare, but I've also heard radar transmitter harmonics getting into audio amp outputs. :-) It'll probably end up being something simple & common though... So what about a wav file dude? My experience has been that hearing the nuances of a particular noise can really help pinpoint it, even if you have to go backwards by identifying what it isn't! Skler |
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#30
Posted to rec.audio.pro
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Dirty Power
In article .com,
"ABacon" wrote: Try a big fat isolated transformer, like a 5kVA Topaz. The can be had through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! What exactly does one of those heavy Topaz Isolation Transformers do? In English ; David Correia www.Celebrationsound.com |
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#31
Posted to rec.audio.pro
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Dirty Power
david correia wrote:
"ABacon" wrote: Try a big fat isolated transformer, like a 5kVA Topaz. The can be had through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! What exactly does one of those heavy Topaz Isolation Transformers do? In English ; I think the Topaz is not a ferroresonant type. So what it gives you is noise filtering (because it acts as a low-pass filter) and also some degree of spike removal as a side-effect of the low-pass. More interestingly it allows you to isolate the power line grounds easily and safely, which can help reduce ground contamination issues. The ferroresonant transformers do all this and ALSO give you voltage regulation, but you have to be very careful about sizing them... they need to see at least half their rated load to regulate properly. They also have the benefit of being able to provide power for a couple cycles if the line drops out briefly. The bad news is that they weigh a lot more than a simple isolation transformer and cost more. Ask an industrial electrician about providing an isolated power panel for you. They might call it "clean power" too. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#32
Posted to rec.audio.pro
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Dirty Power
In article , david correia wrote:
In article .com, "ABacon" wrote: Try a big fat isolated transformer, like a 5kVA Topaz. The can be had through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! What exactly does one of those heavy Topaz Isolation Transformers do? In English ; I have a Topaz 2000 watt resonant transformer. I hate moving it around. Perhaps i will find a use for it one day. The output is not isolated,,, I just measured it, it seems isolated. That does not seem right, at least in Reading Mark Wallers book, an isolation transformer should have one output leg tied to ground by NEC regulation. greg |
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#33
Posted to rec.audio.pro
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Dirty Power
You've all been most helpful, though I admit that there has been more
information presented here than I've been able to intelligently digest throughout the past several days. To "Sklar"... I will post a .wav on Saturday if you are still curious. To those who have been skeptical that the noise I've been experiencing is not affected by increasing/decreasing volume on the amplifiers... indeed you are right. It is incorrect to say that output volume adjustments have no effect - they do. I would say, however, that the effect is minimal, and is really only perceivable in a meaningful way through the last 5%. Again, I am happy to have started what has become a somewht contentious thread. I've learned a lot, and I thank you all for your input whether or not I ultimately solve this problem in my present studio or not. Steve GregS wrote: In article , david correia wrote: In article .com, "ABacon" wrote: Try a big fat isolated transformer, like a 5kVA Topaz. The can be had through surplus outlets for ~$300. Wire it 240/220 in and 120/110 out. It will make ALL of your gear sound better. I have been using one for years and I swear by it. HTH! What exactly does one of those heavy Topaz Isolation Transformers do? In English ; I have a Topaz 2000 watt resonant transformer. I hate moving it around. Perhaps i will find a use for it one day. The output is not isolated,,, I just measured it, it seems isolated. That does not seem right, at least in Reading Mark Wallers book, an isolation transformer should have one output leg tied to ground by NEC regulation. greg |
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#34
Posted to rec.audio.pro
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Dirty Power
wrote in message oups.com... You've all been most helpful, though I admit that there has been more information presented here than I've been able to intelligently digest throughout the past several days. To "Sklar"... I will post a .wav on Saturday if you are still curious. To those who have been skeptical that the noise I've been experiencing is not affected by increasing/decreasing volume on the amplifiers... indeed you are right. It is incorrect to say that output volume adjustments have no effect - they do. I would say, however, that the effect is minimal, and is really only perceivable in a meaningful way through the last 5%. Again, I am happy to have started what has become a somewht contentious thread. I've learned a lot, and I thank you all for your input whether or not I ultimately solve this problem in my present studio or not. Steve Yeah great! That'd be interesting. :-) Let us know how things turn out. Skler |
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#35
Posted to rec.audio.pro
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Dirty Power
GregS wrote:
I have a Topaz 2000 watt resonant transformer. I hate moving it around. Perhaps i will find a use for it one day. The output is not isolated,,, I just measured it, it seems isolated. That does not seem right, at least in Reading Mark Wallers book, an isolation transformer should have one output leg tied to ground by NEC regulation. With a standalone transformer, you can float the neutral. You _cannot_ do this easily if the transformer is installed into a building system and remain legal. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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