 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
24.6.198.63
OK, so I tried the 193L tweak and it works great. But the recommendation was to get rid of my current multiple outlet box with the ferrite rods etc and just use a choke for each duplex outlet. No way will this fit in the current box so its going to have to be a new box.
So I have some questions on the box, outlets etc. For starters what to make the box out of? I was planning on using thick aluminum (say 1/4") plates and aluminum angles at the corners. I've built several power supplies using this approach and they work really well. Some people have mentioned carbon fiber, is this necessary when using aluminum plates?
How should the outlets be attached to the box. I was not planning on having a separate "box" that the usual mounting "ears" attach to, can I just mount the outlets to the top plate?
Which outlets to get. Currently I'm just using spec grade outlets from the hardware store so I haven't tried any of the "audiophile" outlets yet. I don't really have a clue as to which ones to use. Any suggestions?
Power inlet, should I use an IEC input jack and use an IEC power cord or make a captive cord eliminating one "plug/jack interface? If I use a captive cord whats a good wire to use for this. This is not going to be long, its about two feet away from the wall outlet. (which of course I probably have to upgrade as well)
What type of protection should I be using in the box, fuse, circuit breaker (other?)
Is there any advantage to vibration damping the box?
Well that should get me started.
This is all running of one dedicated 20 amp line, total load is about 6 amps o I shouldn't be overloading anything.
Thanks,
John S.
Follow Ups:
John, I'm going to do the same thing. Here are some excerpts from Alan Maher (audionutge) and Al Sekela (on topic of carbon fiber) from various responses to others. Alan and Al please chime in to confirm or revise!
Q. For starters what to make the box out of?
A. "Either one is fine (referring to wood or aluminum). If you decide to use wood I highly suggest a shielding product inside the enclosure. TI Shield grounded to earth would make a nice improvement in the filters performance. I use this technique in a lot of my power conditioner designs. TI Shield can be purchased at Michael Percy Audio."
Q. Carbon Fiber?
A. Excerpt from Al Sekela: "You can get carbon fiber cheap from Soller Composites. You can fix it to the outer face of the aluminum plate with epoxy. Just be sure to keep the conductive fibers out of the outlet slots."... "the major purpose of the carbon is to absorb the energy of standing waves on the power cords. I don't know if there will be much benefit to putting the carbon on the inside. Making the plate too thick will create a mechanical problem for fitting wide plugs.
Epoxy will be an insulator when it cures, and allow the radio waves to pass through to the carbon. Safety is important, so be sure there are no loose fibers of carbon when the plate is ready to install."
Q. How should the outlets be attached to the box?
A. Mounting outlets to enclosure. "I would have recommended a .015" thickness of EAR C-1002 to be secured to the metal cover to isolate the ringing frequency between the cover and outlet straps. Then I would have used brass hardware to secure the outlet."
Q. Which outlets to get? A. Oyaide and Furutech are expensive but recommended often.
Wiring. "Next, lets take a look at the wiring. I don't care what kind of wire you use...that's not important...but what is important is the outlets resonate character. You should place 5 wires per outlet...this is called star wiring...2 hot, 2 neutral, and 1 ground. On the rear of the outlet you will see 4 wire terminals per side (hot and neutral). Place one wire into the bottom terminal and 1 wire into the top terminal per side...this is for input wiring only....now take 1 wire and place it into the 2nd and 3rd terminal per side...this is the outgoing wiring. Why you may ask??? Because the copper wire alters the resonate frequency of the wire clamp inside the outlet. This neat little trick will reduce 50% of your harmonic ringing at the outlet. I like to use dual runs of Cardas 11.5ga for this application and the Cardas 9.5ga for the earth ground."
Q. Is there any advantage to vibration damping the box?
A. I have shock mounted transformers per Alan's suggestion on a layer of Microsorb and EAR C-1002 on top of the microsorb and underneath the transformer. Both in 1/4". Percy sells both. I'm sure this would be good for a choke too. However, I've read that others have mounted the choke to the top of the enclosure similar to a tube amp.
Q. Power inlet, should I use an IEC input jack and use an IEC power cord or make a captive cord eliminating one "plug/jack interface? If I use a captive cord whats a good wire to use for this?
A. "Use at least 18ga x 3 power cord (12ga x 3 is better). Keep the power cord as short as possible...less than 3 feet." Alan has used XLO Reference Type 2 10A power cord (bulk purchase from Michael Percy Audio) for at least one project but is quick to say that one should use what you've found to work synergistically with your system.
The outlets should be as good as your and John's budgets allow. The best in my experience are the Oyaide. However, if another type, they should not have steel parts or nickel plating. A good budget outlet with these properties is the Pass & Seymour MRI hospital grade.
If mounted to a conducting plate, the outlets should be mounted with a conducting (nonmagnetic) screw at one end only. The other end should have a Nylon washer and screw to avoid making a conducting loop out of the outlet's back strap and the mounting plate. Current passes through the hot and neutral wires on either side of the outlet's back strap, so a conducting loop will act as a one-turn transformer. Even if the back strap is not magnetic, this parasitic transformer will cause distortion in the AC.
IME, it is difficult to damp the acoustic ringing of thick aluminum plate. Such materials as Dynamat X-treme are optimized for the thin sheet metal of auto bodies, and are ineffective on thicker materials. A sandwich of thinner plates and a sheet of Deflex rubber would be quiet and sturdy.
Finally, I've found from a recommendation and through experience that the best audio conductor size is 14-gauge. The famous Volex 17604 IEC cord is no longer made in Mexico, and I've not seen any reports on the audio performance of the Chinese replacement (but the report of nickel-plated plug blades is disturbing). Ace Hardware sells a short 14-gauge extension cord with an unplated, molded, right-angle plug. Cutting the outlet off this would make a cheap but effective line cord for the type of DIY outlet box we are discussing. I don't have experience with the Oyaide plugs, but I worry that any screw-clamp connection would be inferior to the welded connections used with molded plugs.
Thanks for the response Al. On the carbon fiber are you refering to carbon fiber mat or a carbon fiber plate that is already impregnated? I have a local supplier with every imaginable type of carbon fiber available, would a thin plate be good for this?
It sound like the carbon fiber goes on the outside of the box, correct? Does it matter if there is an electrical connection to the box?
On the start wiring, what is the best way to do this? If I take the wire coming in and it needs to go to 8 outlets, regular wire nuts are not going to cut it. Should I get a distribution bar with set screws or some other means of "fanning out" the wires?
Thanks again,
John S.
I would get a big soldering iron (80 watts is good) and some big wire nuts. Strip and clean the individual wires and twist together with the wire nut. Tape the bundle next to the wire nut. Remove the wire nut and solder the wires. I recommend a good solder, perhaps one containing silver and no lead. You should have some liquid solder flux to help with such material. Insulate with appropriate materials. Use the wire nuts if they do not contain steel springs (most of them do).
The carbon fiber goes on the outside of a metal box to damp RF standing waves on the power cords. If the box is wood, then the carbon could be applied to the inside and it will do the same thing. It might help with a metal box to apply carbon on the inside as well as the outside. I'm not sure how you would make a solid electrical connection to the carbon fiber: perhaps a brass screw once the epoxy is cured. I don't have experience with "grounding" the carbon fiber; this might or might not help.
Al and I have both used CF as a plate added to the outlet box as a cover or even over an outlet box cover. The stuff we're using is thick aircraft grade blanks, 3/8" thick, and hard to work plus hard to find. In that case it does require an extra large hole to pass the plug barrels through deep enough to seat in the outlets.
I also use in one application a double layer of epoxied CF cloth insde a nylon plate. That works too, but if done with a metal plate, you MUST put it on the exterior. This is easier material to find and work and poses no extra problems with seating a normal or audiophile plug as it isn't very thick at all.
One last way both of us use CF is as a cover/sleeve on the plug barrel exteriors themselves. There are several ways to do this, but easiest is to buy the 1.25" or larger sleeving from Soler as Al suggests and wrap or shrink wrap it into the exterior of the barrel. You can, in fact, sleeve an entire PC if you want, and Al told me it would probably work, but maybe not better than simply placing at the barrels and at the middle and nodes.
I use one last CF trick, but you have to be awfully careful with this one! I machined some of the circular cutouts from the thick plates to fit inside the barrels of the plugs and around the wires. This has to be carefully done so that it does not short or abrade the wires inside the plug. It also works.
Al can supply you (as he's written here several times) with the reasons different CF placements work. I won't repeat those.
In any case, you want to make sure the CF cannot make contact with the circuitry in any way directly, as I understand that CF is somewhat conductive.
Search the archives here. You've touched on at least half a dozen conversations you'll need to bone up on!
Seriously, I've built various strips to my satisfaction, PCs, some of the RFI tweaks, and have recently experimented with audio grade outlets. Each of these is an issue to deal with. Best to set up something that isn't permanent yet that will permit you to experiment in your system, as there's no one right answer overall.
Damping boxes does help. I've settled on cast aluminum, but given what you want to pack into it (I'm not sure of size of chokes or if you intend them to be internal to the box), you may have to construct a special box. Non-ferrous metal gives some shielding; if you make it from anything but metal, consider lining it with copper or somesuch. A guy here recently posted his design using the chokes and outlets in what looked like a wooden box you might like to copy. Mechanically damp the box, the cover plate (I use ceramic for that in mine with a carbon fiber cover too), and isolate or couple (you choose) to the floor or support it sits on.
I don't know if the chokes vibrate (like my transformer simile does), but if so you may want to separate the chokes from the box altogether with a wire tail. Then damp them too. You don't want to add vibrational sources to your box, believe me.
Have had good luck with Furu Cu and now Oyaide SWO-XXX outlets (better). They best my older tweaked P&S outlets by a significant amount.
So far I've used Alan Maher's dual twist power cord design on my strip. You might look that up or try Chris Ven Haus' Flavor whatever cords. Unless this is digital, you might want an unshielded design. Alan's works well with good noise rejection without a shield.
If you use a metal box, how you mount it (how many points of electrical contact on the backstrap/grounding) matters. Read Al Sekela's posts on that issue.
Best I can offer. You'll get lots of good suggestions; read up to satisfy yourself!
| FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
||||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2024, Audio Asylum, all rights reserved ]
