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In Reply to: RE: Lew, It's Testing Not Sides! posted by Dryginger2 on March 31, 2015 at 13:59:39
No one can argue that you hear what you hear. Same for Stu.
As remote as the possibility is, there is the slim chance that one of the panels of your amplifier could become electrified with line voltage. There should be a safety system in place in the form of a low resistance connection of the metal enclosure to earth, which should draw enough current to trip a breaker. If that safe path is interrupted, the next path is through any conductive element that comes in contact with an electrified panel of the enclosure, such as a human. Without the safety ground in place, there is no way to know such a condition exists except by receiving a shock, the severity of which cannot be predicted.
Before you promote this tweak any more, please do us all a favor and test the continuity of ALL of the panels of your modified amplifier to each other, especially whichever one has the earth ground bolt in it. You can use an ohm meter and read actual resistance if there is any (a fractional amount would be safe), a continuity tester, or even a flashlight bulb, battery and some wire. There is no cost to do this, so it fits your requirements.
If there is not continuity among ALL panels, please promise to stop telling people to do this. If there is continuity, I promise I'll stop being critical of it. If you ignore this third request to address the safety issue, you will divulge something crucial about the sincerity of your pledge to help audiophiles realize better sound.
I have one more question: did you test the screws you removed to see if they were, in fact, magnetic? I am not demeaning your tweak. I use only non-magnetic resistors, and my tweeters and midrange drivers are mounted with plastic bolts. I'm not sure something as insignificant as chassis screws can contribute, but you hear what you hear. Unless you're dead.
Peace,
Tom E
Follow Ups:
Tom E,
Yes, I did expose all the original manufacturer's screws to a magnet and was surprised to discover that three-quarters showed an attraction, perhaps a third as strong as had ferrous screws. Since this was a cross-application exercise from UncleStu's speaker tweak, I started off with brass screw substitutes for case machine screws but their presence degraded the sound by changing the tone. So then adopted nylon/ plastic for all machine screws and was apprehensive of their capacity to resist stress. I need not have worried as, despite regular screwing/ unscrewing the plastic/ nylon machine screws of all sizes and holding the unit upside down/ on its side for access, the screws did not sheer with one exception. I was tightening a screw into a screw-hole where, unbeknownst to me, there was a remnant of Teflon tape whose added resistance caused it to snap. Thereafter I took great care to inspect and clean all screw-holes.
It was frequent testing of the warmth of the LFD LE4 heat-sink with my fingers many times daily over many days before I concluded that it was safe to substitute plastic/ nylon for SS machine screws there as well. Since most amplifiers run hotter, that is not a safe application that can be recommended for most users.
Am unclear as to what you want me to do with the electrical testing because that is outside my experience/ have no equipment for solder for bulbs to wires to batteries and must now sleep. With the slightest electrical concern, I simply detach the components concerned from the circuit. Much appreciate your spirit and will do what I can that I do get to understand and does not cost much money. (I find that the AC internal ground is tightened directly against the case by a plastic/ nylon screw with a brass washer in between the ground and the plastic screw-nut.)
Take care,
DG
Interesting that some screws are magnetic; others, not. I can see screws that hold PCB's in place might have an effect on signal, but probably not the chassis panel screws. They're just too far away and too small to have any audible effect.
If you substitute plastic for metal between panels, then there is a good chance of breaking the path of safety ground. If you don't understand that, then quit messing around with it and retract your previous recommendation and put the metal screws back in.
If the panels are coated with paint or anodized, they will not conduct from one panel to another without conductive screws inserted into bare metal threads. You put Teflon in the holes? Get all that shit out of there. Put the plastic screws in, if you insist that it makes such a difference, and test for electrical continuity from the panel that contains the ground bolt to all the others. You will need an ohm meter, available for a few bucks, or a continuity tester, usually a feature on the ohm meter or sometimes available separately, or you can make your own continuity tester with a battery and flashlight bulb. No soldering needed. Hold a wire against one end of the battery. Hold the other end of that wire against one terminal of the bulb. Now hold a wire against the other end of the battery. With your third hand, hold the other end of that wire against an enclosure panel. Your fourth hand holds another wire against the ground bolt panel, and the other end of that wire against the other terminal of the bulb. You should have a circuit of
battery-wire-bulb-wire-grounded panel-different panel-wire-bulb-battery.
If current flows through two different panels and lights the bulb, you have continuity and the enclosure is safe and I will finally leave you alone. If the bulb doesn't light, replace the metal chassis screws and quit while you're ahead and alive. I suppose you could try the test with the metal screws in place, just to see if you were doing it right or I'm full of shit.
The only other way to connect panels is with a wire firmly attached (screwed) to a conductive surface on each panel. Or you could try scraping any coating away where panels touch. This is a bit risky, and might not be UL approved if that sort of thing worries you.
Of course, all this is true only for enclosures with exposed metal surfaces. Wood is good.
You might play your stereo for a hundred years and never develop a fault. You might play a hundred stereos for a hundred years and never have a fault. You might turn it on tomorrow and get an unpleasant tingle or thrown across the room. That's why every metal part of it should be grounded.
Peace,
Tom E
Tom E,
Thank you. The risk factor is very small as you yourself stated and I recognized this morning that this particular safety concern is a monkey on the shoulder of your multi-handed anxieties and that's where it should stay. So, being technically qualified, please test it and report back to the forum (nobody will do a better job, you will be fair AND your sound will benefit).
I have for various reasons touched most parts of my amplifier under power since substituting plastic machine screws and never experienced so much as a tingle. Whereas the Denon CDP/DVD 2910 with a two-prong plug/ no ground by design and the substitution of very few plastic machine screws frequently delivers a tingle when touched during operation. For that reason I turn it off/ disconnect it at night or when absent.
Am sincerely looking forward to reading your report.
DG
I am reporting you to the moderators. Your suggestions are dangerous and it is a liability to Audio Asylum to allow you to post here.You are a dangerous fool.
Regards,
Tom Ernst
Edits: 04/05/15
how all the naysayers have to to do is to kick back and offer experimentation: they never need to experiment on their own adur to their intellect.
oh well c'est la vie
Hey, it's not my tweak, so it's not my responsibility to test its safety. Got that? I'm trying to prevent someone from being electrocuted or at least shocked or burning down their house.
I am not a naysayer. Got that? This is really starting to piss me off.
If someone substitutes plastic chassis screws for conductive metal ones, as DG is promoting, and they break the path of safety ground from one panel to the safety ground post in a different panel, they may be intentionally defeating a safety feature and there is a risk, albeit a small one, that someone could get hurt. If there is still a conductive path, then there is no risk and I'll gladly shut up. The only way to determine that is by testing for continuity from one panel to another, ALL of them. I do not need to perform the test because my enclosures use horrible, distorting, crude, magnetic, conductive screws. My stereo sounds like shit because of it, but I won't die from touching the enclosure.
I am trying to educate the man and warn others, and you make snide remarks. You want to ignore liability, fine. Someone's lawyer will snap you, and possibly AA, out of your fantasy tweak world pretty fast.
Do you know the difference between EMF and RFI?You do realize brass screws are more conductive than steel or stainless, right?
Do you understand Faraday's laws? I can reiterate them for you if necessary, BTW.
Funny how old tuners from the 60's used expensive copper plated chassis, enh?
Oh yeah top of the line Sony and Pioneer digital machines use copper plated screws for assembly tooAlso you use non magnetic screws ads hardware already for your speakers. Why shouldn't it work for a chassis holding a big transformer?
Edits: 03/31/15
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