It really depends on what the source of the hum/noise is. You need to define the problem before throwing money at it.
Sometimes they can help. The most graphic illustration I can think of is that I used to have a pair of Martin Logan Prodigy speakers. They had a little blue "ML" logo that lit up on the front when a signal was present; if a signal was not present for a sufficient time, they would actually go into sort of a shutdown mode. But, the little blue lights were always on in my house. Until I got a power conditioner. As soon as I did that, the little blue lights went off. So, there was obvious some kind of line noise impacting the signal path.
Oh yeah, it sounded better too. ;)
Again, I'm in agreement with Sean. Hum, from my experience, is not remedied by power conditioning. Dedicated lines first: absolutely! Then a good pc and you're on your way to electric nirvana. (oops, don't forget those power cords, as well. not easy to do inexpensively) Treat your electric as another fundemental component. peace, warren
In some cases, even dedicated circuits or power conditioners might not help. If the house power system is not grounded properly or there's excessive current in the neutral wiring (dimmers, fluorescents, computers, etc), or if strong external RFI/EMI is present (nearby radio towers, radar facilites, etc) then no power conditioner will help short of an isolation transformer. Power conditioners are not a cure-all; it's like saying all a wrecked car needs is a coat of wax.
I think that we are all in agreement here. That is, even dedicated lines, line conditioning, etc... can't solve a problem that is component or system based. How about describing the problem that you're having? Someone here might be able to point you in the right direction.
Gs: "it's like saying all a wrecked car needs is a coat of wax"
Isn't that like the old saying about a "dog" of a muscle car i.e. "if it don't go, chrome it" : ) Sean
Gs5556 puts his finger on the problem that has just been solved for me by an isolation transformer.
Since home heating season began this year in Montreal (and electricity use went up), I had been getting a hum on my bedroom lullaby system (HK 930, Paradigm Titan) that made it unusable for me, no matter what the volume setting. Adding a CDP made it worse, doubled the hum volume. The darn hum went up and down in volume, like a prop-driven small aircraft buzzing the neighbourhood. (OK, it was hum plus buzz... ).
I found a small (250VA), very cheap isolation transformer on eBay and it has cut the noise down to a viable level, not gone, but slightly more than just perceptible.
My main system is on a dedicated line and I get the same hum there, but at a much lower level. I've put the transport on a Deltec 500VA hospital-grade isolation transformer and the results are so good that I intend to give the entire dedicated line similar medicine.
You may want to try this before you spend much $$$.
I had a sporadic hum that I thought was in the AC line. I ran a new AC outlet back to the circuit breaker but it didn't cure it. I discovered the cause by accident when I disconnected the cable wire from the back of my TV and from the wall to rearrange some wires. The hum disappeared completely.
It comes back every few months but I just disconnect the cable line and reattach. It must build up a charge over time. Worth a try.
Tobias: I'm glad to hear of your results. I've been advocating isolation transformers for several years now and have helped others find suitable models for their given installation. Lak and Psychicanimal can testify to the benefits involved and i'm certain that others can too. That is, when the iso's are properly selected and installed. You might want to do some further research on the subject in the archives before investing more money into various iso's as some surely work better than others. Some iso's are more prone to introducing problems into the system, both due to poor design and improper selection for the intended application. Sean
Sean, thanks much for the tip. I have done a bit of research here and lurked eBay. The best kind appears to be what's called an ultra isolation transformer with very (high? low?) internal capacitance, on the order of 0.0005 pF. I have a 220V three-wire line (2 hot, 1 neutral, and I can run a dedicated ground) ready for use as the new audio circuit, so what I need is bucking and isolation.
I don't know if single transformers exist which can do both jobs, but that might be the ideal solution, if I could find it.
My problem is my relative ignorance in the domain. I can wire up a house and build an amp kit but I don't know enough to ask all the right questions of an eBay seller, or recognize that a tranny has the right taps by looking at it and its specs.
Could you possibly suggest a basic reference on the subject?
Tobias: You don't need a bucking transformer at all. You can simply use a 220 - 240 volt transformer and separate the legs down to two 110 - 120 volt lines. Personally, i prefer to keep all of the equipment on one leg of the 220 line, but there are those that have split them and never run into problems. Many of these transformers can be run with multiple taps i.e. 110/120, 220/240, etc...
The spec's that you quoted as far as capacitance and "ultra isolation" are right on the money. The only other real factor is current capacity. This would be the rating in KVA's. If you have a 5 KVA ( 5000 watt ) transformer and are running it at 220 volts, you can use ohm's law to tell you how much current it can sustain. Divide 5000 by the input voltage ( 220 or 110, etc... ) and you'll arrive at how much current the transformer can pass. As mentioned in other threads about this topic, i recommend staying below 60% of the rated capacity of the transformer if possible. That is, if your entire system adds up to 2000 watts of draw, you should have a transformer capable of 3 KVA ( 3000 watts ) at the very minimum. A 3.5 KVA unit would be better and closer to the ratio i described. Obviously, a 5 KVA would provide even more headroom with the potential for an even lower noise floor due to less noise induced by the transformer itself.
Hope this helps. Sean
Warren, i'm sorry if i never got back to you about this subject. I sometimes get plastered with a large quantity of emails at one time. As a result, i sometimes end up losing track of where i left off at or which ones i had enough time to read but not enough time to respond to at the moment. By the time i log back on, more email has shown up and i get lost all over again.
If you would be kind enough to do so, please post your question publicly and i'll do my best to answer it. This may help others to follow along too, reducing some of the emails i may end up getting that ask similar questions. Sean
Cdc: Each of these are different designs with different outcomes. A choke regulated supply should lower the noise floor and provide less ripple ( voltage fluctuation ). The isolation transformer won't do anything in terms of reducing ripple, but it should lower the noise floor to a measurably greater extent. That is, in terms of how most chokes are used in most power supply designs. Given that i prefer to run the Iso at the breaker box / out of the listening area and the other approach is actually built into the gear, one could actually use both with compounded benefits. Sean
I had the same exact problem on my system. I was able to do it by simply puting a 2 prong to 3 prong adaptor onto all of my power cords. This eliminates the ground loop on your house's circuit and if that is the source of the hum (which it most likely is) it will cure it completely. I went from almost unbearable hum to quiet as a desert.
You want bang for the buck. Go to Home Depot and purchase a Belkin AV Master for $75...that right...$75. I am using one with my Naim CDX...only Power Conditioner that totally gets out of the way...lets the dynamics come through...along with the detail. I stumbled into this when I tried it with a Roted 965LE, with miraculous results...I was all set to go for the HYDRA. The Belkin offers amazing bang for the buck...I now own two of them...an amazing product providing you don't believe you have to pay $1,000 for this kind of result.