Now that we know where AC line noise is coming from and that our homes are vulnerable to all the generators of noise, what to do about it? Our options have pretty much always involved creating safe havens for the equipment that will benefit from it.
Safe havens are isolated areas of power that we build using either a filter or a regenerator like a Power Plant. But what about the whole house? Would it be possible to create a whole house safe zone for power? Probably not since homes take a lot of power, on the order of hundreds of amps and, besides, who cares? We don't benefit from cleaner power driving our washing machine, dishwasher or stove.
We do, however, benefit from cleaner power with our AV equipment including televisions, stereo systems and computer audio products. These can have demonstrably better performance with cleaner power.
Several of you have asked me why we don't just place simple filters everywhere we want clean power. After all these simple filters convert noise energy into heat and create lower noise safe zones pretty effectively. The answer is performance, the very goal we're trying to achieve.
Whenever you place a series filter inline with the power feeding equipment you risk performance loss if the filter is aggressive. There's just no getting around it - as designers we can minimize that loss and create a product whose benefits outweighs the loss - and that's what we've done in a product like the Dectet. None the less, the Dectet is in series with the power and will limit, to some extent, all the possible benefits of unrestricted AC that's been cleaned. The same is true for any series AC product of which most are.
The good news is that using a properly designed series filter like the Dectet brings far more benefits to the table than not - the bad news is that we have to restrict how much noise it can clean. Let me explain. The last thing we want to do is produce a line noise filter that restricts dynamics or bleaches out harmonics in the music - as most filters do - so we have to limit the amount and frequency of the noise we lower in order to make sure we never violate a user's trust in our ability to make better sound. That comes at a price - for if we didn't care, we could make a far more aggressive filter that really romped on the noise - but then you wouldn't be happy with the results. Cleaner power, worse musicality - not a combination we're interested in having anything to do with.
So the goal would be to reduce line noise before the filter to help a well designed filter do its job. To have that happen, we'll need to build a filter that is not in series, but rather in parallel - thus no restriction placed in the AC line. Great idea, but unfortunately traditional parallel filters have two main problems: they cannot eliminate or lower AC noise without just rerouting it and they are not very effective.
We'll start looking at the world of parallel filters tomorrow.