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Hey Al thanks these things are wonderful. I built two. One is connected to my P-300's output(which only feeds my CDP) and one to my outlet strip that feeds my system. The HF is so much clenaer and nicer. I took my most silibant Cd's and they were way better. I took some Cd's w/synthetic sounding percussion and they were way cleaner. My noise floor that was small is inaudible now. I ended up finding X-caps at Mouser. They have a nice 10% Vishay w/axial leads. I found them listed as safety caps. They are non-magnetic too. I used metalized film 1% Vishay resitors. All the parts to make two were less than $20 shipped. Thanks so much. I also made a schematic of sorts using wordpad for guys like me that can't visualize well from the written word. For testing purposes I used cardboard to mount the parts and snagged a couple of polarized power cords, cut them 6" long and connected the power cord to the circuit which I put in a ziplock bag taped shut. Now that I found them wonderful I will permanently mount them in a better manner.ET
Edits: 01/12/08Follow Ups:
Then, we'll take you seriously!
So, what the parts costs for this, just the caps and resistors?
I did find that a noisy MOV is REALLY bad for audio. They must age or something.
First off, they work beautifully. I spent years with Al working on this stuff. Have a set of them in my house, including some of his last experimental versions.
Second, Awe-d-ofile does sell them for cheap.
Third, don't be fooled by the simplicity or the lack of expense.
Fourth, this is an old design of Al's. He upgraded after that, but the idea is the same.
Fifth, you have to make damn sure you use safety rated caps for your voltage, so if you are now convinced it's worth the try to DIY, read the later posts and do it SAFELY!
I'm looking at this and don't completly understand how it's connected. Would this be wired between the hot and neutral going to a component. Or is it wired between two dead end wires originating at a wall plug?
Thanks,
Bill
You have several options, but all are hooked up between hot and neutral on an AC line, and the values given are for 110-120V systems and the caps must be X or Y rated for AC safety. As I recall, the R side goes to the neutral.
I use them in 3 ways:
1) in their own plugs (with a PVC jacket for safety)that you plug into your wall or other outlets
2) where I join a snipped captive power cord to the new DIY power cord
3) where I join the PC to a toroid in a PSU.
Where and how you put and house them is a matter of safety concerns, so know what you're doing!
These work cumulatively and you can use them in not just your audio system but anywhere in your house circuitry that noisy stuff plugs into (computers, TVs, appliances).
In my case I've upgraded them with carefully constructed and damped Ti-Shield that's grounded. REad up in the archives how to do this.
just curious about the similarities and or differences
OK, now consider the Ti-shielded and grounded variety posted several ways recently. These are another significant upgrade.
And these things I find to be cumulatively beneficial, not just in the audio outlets, but also in household places that have significant sources of RF, like where your TV or computer are plugged in.
Your approach of using only film caps is a good one. I have a friend who dislikes ceramic caps, and the smaller sizes of X and Y caps are usually only made with ceramic. I will have to try your combination.
Thanks also for confirming that the Vishay caps are nonmagnetic. This seems to be important.
Finally, I'm in the middle of an evaluation of the resistor value that works best. My 120 ohm figure was calculated from crude measurements of some house wire cable. A lower value, such as 100 ohms, may work better. Keep in mind that your close spacing of capacitor values will result in a lower net resistance over most of the frequency range. Stay tuned.
Another reason I chose the Vishay cap was not only its axial lead style but the fact it was the only with 10% tolerance. The others were all 20%. I chose .47,.33 and .22 values because that's what they had. Finally you say 100 ohm resistors might be better. Can you tell me why or what sounds better w/100 ohm vs 120? Thanks in advance.
ET
The primary purpose of the resistors is to damp resonances on the house wiring. The ideal way to stop a cable from resonating is to terminate it with a resistor that matches its characteristic impedance. The capacitors are there to keep the 60 Hz power waveform out of the resistors, as they would have to dissipate on the order of 120 watts if connected directly to the line. The larger the net capacitance, the lower the corner frequency, below which the filter has diminishing effect and above which it couples the resistor to the line.
In your case, the capacitors are closely spaced in value, so they will have overlapping effective frequency bands. The effective R seen by the line will be one-third of 120 ohms for frequencies above the smallest capacitor corner frequency and below the largest capacitor resonance frequency. This may be a good thing, as there will be ultrasonic noise on the line that is below the house wiring resonant frequency range. The lower the resistance this noise encounters, the better.
My house, and two of my dedicated audio circuits, are wired with Romex-type plastic jacket cable. I measured the inductance and capacitance of a sample of similar cable and came up with the 120 ohm estimate for the characteristic impedance. Other types of wire, such as armored cable, would have different values of characteristic impedance.
Making R too large (compared to the type of wire used for the house circuit) results in underdamping and some ringing from reflection of the noise. Making R too small results in overdamping and reflection of noise.
I'm doing experiments with different values of R. At this time, 110 ohms sounds best. To me, overdamping sounds closed-in, while underdamping results in excessive treble artifacts. That is just my system, though, and other systems may have different results. The TI-Shield bartc mentioned may also affect the performance so that the optimum value of R may change.
These are small performance changes. I would not worry about experimenting with different R values unless you have a lot of time and interest. The TI-Shield has to have at least a week of burn-in before you can hear something close to the final effect.
Thanks for the detailed follow up. I think in my next builds I will try 100 and 110 ohm values. I do notice that w/120 ohms that the HF is up a bit. That is not unwelcomed in my warmer system. I also did some lisening with the device only and my Richard Gray removed. I had hoped it was as good w/o and could therefore sell the Gray. I found however that the Gray imrpoves the soundstage when its connected. Oh well. I may find I like a unit w/100 ohm on the CDP to tame the HF a bit but w/120's on the amps. I will fool around with various combos and see. Thanks again! I'm enjoying them very much. It is one of those tweaks that makes you want to listen to all your software again, not just those "in recent rotation" so to speak.
ET
Making major improvements with cheap tweaks is a lot of fun.
I've learned not to discard apparently boring discs, as sometimes a tweak will reveal their interesting aspects.
Hi, I like the idea of the RC combos butI take it that the discussed values are for 110V 60Hz mains supply. What would your suggestion be for 230V AC at 50 Hz? thanks, tim
These are made for world-wide applications, so they are listed by the European and Asian agencies as well as the USA.
Hello Al,
What resistor value would you recommend for 50hz (France)?
What brand of cap sound the best I see Rifa is making ones with paper some are MKP (vishay)....
Have a good day: David
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