cstokely@decwrl.dec.com (06/24/91)
It's time for me to do something about the power to my audio system. I have 1.2Kwatts of power (total in 2 Bryston amps), a Bryston pre-amp, Infinity cross-over net, a Cal Audio CD player, and some fine speakers. All the peripherals' power cords are plugged into the pre-amp, and the pre-amp and 2 amps are plugged into a power strip. (it used to be a surge protector, but the local power company took care of that recently with a nice powerline furball.) The power strip is plugged into (ahem) a 3-prong adapter which goes into the 2-hole wall socket. What do you think of voltage regulators or something just short of a UPS for this system? Got any to recommend? What about the 3-prong adapter? It has a copper braid to the wall box, which seems to have a ground attached. Should I really just have an electrician come give me a grounded 3-prong separate circuit for audio? When I power on the amps (1 at a time), there is a definate dimming of the lights, and some time the refrigerator even coughs. (love these old homes ;-) What is the reasonable solution to the power delivery? I'm sure I'll hear the difference in the speakers. What is the ultimate solution, assuming money were not much of an object? (short of my own substation, of course.) Looking forward to an ozone-free discussion, ..Celeste Stokely cstokely@btr.com
miker@polari.UUCP (Mike Ranta) (06/25/91)
In article <13357@uwm.edu> btr!cstokely@decwrl.dec.com writes: >It's time for me to do something about the power to my audio system. >What do you think of voltage regulators or something just short of a >UPS for this system? Got any to recommend? rong I do not recommend voltage regulators. They operate by "stepping" between multiple transformer taps as the input voltage and/or load varies. Each time the device steps to the next tap, there is a small but abrupt jump up or down in the voltage. These jumps alone are a source of noise and sonic problems. The popular Tripp-Lite units sold for audio use operate exactly this way. They also will probably degrade the power output of your Bryston amps which require a great deal of current--more perhaps than even the large Tripp-Lite unit can provide. When you push your amp hard, the regulator is going to be actively stepping between taps somewhat in step with the music to try and respond to the rapidly changing load the amps are presenting. This has to be far worse than the minor variations that may be on your power line. The transformer(s) in your amps already provide isolation from the power line. The large filter capacitors go a long way toward removing noise, minor variations, etc. And in the case of Bryston amps, I believe the gain stages are already electronically regulated. To make a long story short, I cannot believe an external regulator or other magic power conditioner is going to help anything. I do, however, highly suggest a good surge supressor. The stand alone variety for about $50 (versus the ones built into power strips) are the way to go and many have lifetime warranties along with built in monitoring circuits. Some even warrant the equipment connected to them. The good ones will survive many "hits" from your local power company. These devices also remove some RFI from the line which can't hurt. >Should I really just have an electrician come give me >a grounded 3-prong separate circuit for audio? If your outlet is really grounded through the center screw, you should be ok. Even without a ground, most audio systems are happy. The ground is important for the surge supressor to work correctly, however. >When I power on the amps (1 at a time), there is a definate dimming of >the lights, and some time the refrigerator even coughs. (love these old >homes ;-) The lights dimming when your large amps power up is normal. They are drawing hundreds of amps to charge the filter caps in less than a second. Obviously, heavier wiring (and more direct runs to the power panel) help this problem but are usually not practical. >What is the reasonable solution to the power delivery? I'm sure I'll >hear the difference in the speakers. What is the ultimate solution, >assuming money were not much of an object? (short of my own substation, >of course.) I can suggest only that you use a good surge supressor, make sure the outlet is grounded, and if you want to spend more money, put the audio system on it's own 20 amp 12 gauge circuit. Will you hear a difference? Probably not, but you can sleep better knowing the equipment is safer. Will you hear a difference with a regulator? Yes, it will probably sound worse! Finally, I'm sure some of you out there believe power regulation is a wonderful thing, and I'm just waiting for the flames. This is only my opinion represented above, but as a designer of power amplifiers and a devout audiophile, I'm fairly comfortable with my comments. miker@polari.uucp >
bms89@ecs.soton.ac.uk (Scally BM) (06/26/91)
By the sound of it a complete rewire could be in order, failing that a
dedicated line for the HI.FI. would be a good idea, this would be easiest.
My experiance of dedicated lines.....
When my parents last moved I managed to perswade them to let me put in a
line for the system (tar Mum). I didnt realy notice the difference untill
(in the same house) a rewire forced me to lose it. This was a subtle but
great loss.
Power conditioners....
The best ones I have tried (in the UK) are made by Lynwood electronics
there are other brands, I have a suspision that the each system may
respond differently to different power conditioners. He does make a 1K2W
version
Tiggerbms89@ecs.soton.ac.uk (Scally BM) (06/26/91)
I'm about to ramble again..... In my opinion most powersupplies are very capable of coping with LF modulation of their source (mains). The harmonics commonly incountered due to hystersis in the core are again at relatively low frequencies up to about 5th at low levels. HF noie- due to the increased use of switch mode powersuplies and the surges caused by diode conduction present lots of HF noise. Standard powersupply electolytics are not that good at handeling this. Thus in a well built amplifier there will be devices to remove the HF noise thus preventing it from causing distortion to the signals. So far so good... no flames yet??? Due to cost cutting pre transformer hf filters, and post transformer bypass filters are often left out. Consider the specifications though.. This devige has to 'repell' noise down to 7K (at low levels at the bottom frequency) yet be capable of responding to current transients at up to 20K. Hummm A tad of a design problem I fancy. Any help will of course benafit the sound but to much control will strangle the life out of the system. QUERIES Has anyone ever tried there system on it's own generator?? Sugestions.. A device that filters and rectifies the mains and then modulates it at a constant frequency (50/60hz) with enough power to run an amplifier (or two..) you are right this is getting silly. Such devices are available.. for turntables as well... Why not just go and get a nice line from the electricity board... remove nasty transients on the way to a good size transformer, nice not to noisy diodes, good smothing and there you are. with a good powersupply. and hopefully good sound. That is how it should be but for economies.... Tigger
miker@polari.UUCP (Mike Ranta) (06/27/91)
In article <13454@uwm.edu> bms89@ecs.soton.ac.uk (Scally BM) writes: > > I'm about to ramble again..... (good stuff deleted...) > Thus in a well built amplifier there will be devices to remove the >HF noise thus preventing it from causing distortion to the signals. > > Due to cost cutting pre transformer hf filters, and post transformer >bypass filters are often left out. Power amps usually have at least an RFI supression capacitor on the secondary of the power transformer. The transformer itself also provides a great deal of attenuation. > Consider the specifications though.. > > This devige has to 'repell' noise down to 7K (at low levels > at the bottom frequency) yet be capable of responding to >current transients at up to 20K. Hummm > > A tad of a design problem I fancy. This is not the case. The filter capacitors in an amplifier cause the input current to be very low frequency. If you put a small value resistor in series with the AC line and monitor the current waveform with a scope (watch out for common mode voltage) you will see a very low frequency waveform (typically far less than 100 hz). We're talking about orders of magnitude here which makes filtering an easy task. > Any help will of course benafit the sound but to much control >will strangle the life out of the system. This is not true. While RF junk on the line can certainly cause audibile side effects, the filters themselves, unless they inhibit current at a few hundred hertz (which would take a HUGE inductor) do not create any problems of their own. > (More stuff deleted...) > A device that filters and rectifies the mains and then >modulates it at a constant frequency (50/60hz) with >enough power to run an amplifier (or two..) you are right >this is getting silly. Such devices are available.. >for turntables as well... This would be powering an amplifier from essentially another amplifier--your're right, that is silly. The moral of all this remains the same: A good RFI filter and surge supressor between all of your audio equipment and the wall is a good investement and certainly can't hurt. A dedicated circuit for your system may also be of benefit. Anything else, however, is either unnecessary or possibly even detrimental.