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In Reply to: Hammond choke 193L installation for dummies? posted by cporada@cabnr.unr.edu on April 21, 2007 at 18:00:39:
The choke works so good for me that i am thinking of getting more. The question is whether we need more than one? or it won't help? or it helps if the AC line is really dirty?
Follow Ups:
We don't know until you do the experiment and determine the point of diminishing returns.In my house, I use a 1 KVA filament transformer with a damped secondary in place of a Hammond choke as a parallel filter on the dedicated AC circuit that feeds my Wadia CD player. Even with this device, I find benefit from treating the other dedicated lines to my monoblock amps, and the other convenience outlet circuits throughout the house. Filters at the primary noise sources also help.
Think of damping your house's AC circuits in the sense of damping a car's suspension. You may recall seeing an old junk car with inoperative dampers ("shocks") on the highway: the wheels bounce up and down continuously and the car bounces several times every time it hits a bump. This is like your house wiring without chokes or dampers installed. The effects of RF noise are magnified by resonances in the house wiring.
On the other hand, there can be too much damping. Put racing dampers on a passenger car and the ride is seriously degraded. Too many chokes or too much resistive damping may increase the reflections of RF noise within your house wiring and degrade the audio system performance.
Since the optimum amount of damping is difficult to predict, buy the chokes a few at a time, let them settle, and listen carefully for improvements. If adding a choke does not seem to improve things, move it to another circuit or put it aside. You may need it later if you change the wiring or set of non-audio appliances in your house.
Honestly, i don't really know.Right now, i plug the choke in the second outlet in the the chain. My gears connected to the first outlet in the chain. There are about 10 outlets through out the room and an ajacent room. Luckily, my gear is the only item using power in this circuit line ( i would consider it as a dedicated line).
I think i will one more to see if it gives improvement.
especially if you have contemporary non-audio appliances that may be strong RF noise sources. Things like digital video recorders (TiVo and the like), microwave ovens with complicated controls, high-efficiency furnaces, personal computers, garage door openers with rolling codes, etc., etc., all seem to contain switching power supplies for the computer controllers these days. They generate a lot of RF noise and put it back onto the AC line.In-line filters for these things can help a lot. Many surge protection power strips also contain EMI/RFI filters.
I'm hardly an expert but just wanted to remind that some EMI/RFI filters are themselves sources of noise . . . it would be nice to have the ability to calculate and to measure/evaluate just what is really needed to do the job right. Not something I am currently in a position to be able to do.
There is some benefit with the common surge protector strips, which is why I recommend them. The MOV surge protection devices within them are reported to be noise sources, and the circuit-breakers, pilot lights, switches, and general flimsy construction all make them less than ideal.However, they are easy for non-DIY audiophiles to find and install.
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