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ncc74656

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Posts posted by ncc74656

  2. Posted

    i was hoping M5 (or someone else) might know of a place locally that does a mix of electrical work. i had a customer drop off a large LED sign board that runs off 220V mains with seriesed 110V inverters into about 88 separate micro controller boards that run off 24/12/5.6V and control small segments of RGB led's.  the panel blows breakers upon power up. its beyond the scope of work that we do at my shop and wanted to give the customer and idea of maybe where to go.

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  4. Posted

    want to make sure im not deceiving myself.  if i have 3 wires on a long run, going into a fuse holder and then a single short wire going from the fuse to the battery, it should be able to handle the current with out significant voltage drop due to the short run and low resistance, right?  by the math the short run can but when paired with a long run behind it... i guess im not sure how to do the math when the wiring run changes size.

     

    so three 00 over 11 feet into a single 00 for 4 inches or so to carry around 600A. that will work right?

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  7. Posted

    nice. well im going to try my hand at making some copper terminals for my 2nd battery up front. im still going to coat the other al ones i made and just see how they get on.  i REALLY love the idea of threaded holes and i dont think i can do that with the copper but we will see... 

     

    side question,  many amps and terminal blocks i see have set screws in them and it seems the terminals are al? i can scratch them and use vinnigar to test if its al right?  

    is there a way to 'plate' al? like in a bath with a battery? i haven't googled this yet, first time i thought of it.

     

    thanks.

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  8. Posted

    can copper be stacked? lets say i want to build for a max current of 500A. i can pretty easily get .25" copper but not any thicker. so if i had .25x1.25" that could carry around 300A. could i take two .25x1.25 and stack them to get 600A of current? and if so do i just bolt them together or solder or braise?  in an ideal world id like to have a .75" thick copper bar to drill and tap holes into for bolting ring terminals to. 

    as for contact area - i cant seem to find any good data on contact patches. it does not make much sense to me that you have a thick bar with say 1/0 cable coming in and then a ring terminal with about 1/8 square inches of contact surface area on the ring terminals...  i dont have any of this installed yet so i cant do a voltage drop test. i want to get things right before i install (or as close as possible).

    i built some aluminum battery terminals yesterday that seem to be working very well. i am picking up some of that paste that prevents corrosion. im concerned by the shrinkage of aluminum compared to copper so i guess ill find out if my bolts come loose in a couple weeks...  i wish i could find a 1X4X15" brick of copper, that would be perfect for what im doing. its just so much easier to find aluminum in those sizes and WAY cheaper. 

    you mention copper can be much thinner - from what i have read and was told by people in the AC electrition field (no idea how DC changes things) aluminum must be upsized by about 25% to carry the same current as copper, the load isnt the major issue in their field but rather the terminal connection and how much more aluminum expands and shrinks by temperature.  i think thats right?

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  12. Posted

    it got very cold around here and like many others i just bought two new batteries for my truck, these are just factory but AGM upgraded.   now in an audio system lets assume i have enough wiring to transmit power with negligible losses from under hood to back seat.  if i have two batteries at 1150CCA up front and put an older battery in back on the amp rack (say a 900CCA agm) will i run into issues with having a less than new battery back there?  lets say the battery tests out at 80% of its rated cca (so still a decently good battery i think), when the amps pull power will it have a similar effect as a cap can have in that the alternator is now trying to charge the battery up as well as the amp, increasing the load on the alternator or would the fact that its got capacity over ride any negative impacts on the charging system (would it even have any?)

    would it be better to just keep the two batteries in front and not add a 3rd in the back?

    i know an older battery can drain a newer one when left sitting in parallel, id probably be isolating the rear battery from the front two while off.

     

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  13. Posted

    can MLV be stacked to provide better results? for instance if one has 1/8" 1lbs per sq/ft can you put two layers on to get double or close to double the effectiveness? if so how should the sheets be orientated? front to front, back to back, or in the same direction? you couldn't glue it together right, because that would lessen its effectiveness?

    when installing into doors it should be affixed around the edge but left relatively free floating other than that, right? my understanding is if its rigidly stuck down that it will lessen its ability to absorb sound.

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  14. Posted

    just to try it i stuck some deadener over the spray on and i could hear a drastic difference in panel noise when i tapped it so it does something, that being said i have no way to measure the loss in efficiency compared to directly on the metal.

     

    i plan to stick some over the spray on and then cover that with the MLV, getting burnt out on this projecct and just to much work to redo things. at this point im going for "accecptable" over perfect

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  15. Posted

    ok, ill see what i can do with this MLV i have then, its fairly heavy @ 1lbs per square foot.

     

    i guess my primary question is, does adding multiple layers of peel and stick dynamat do anything? my understanding is the sticky side resists the movement of hte panel and it deforms at a different rate than it returns. so if you put a layer on top could it really have any effect since its no longer attached to teh panel you are trying to dampen?

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  16. Posted · Edited by ncc74656

    i didnt intend to say the peel and stick deadener is useless but im thinking, if i put enough on to make the panels not vibrate (say 30-40% coverage) then my money would be better spent doing a damper after that rather than more deadener. right?

    my coworker used 5 layers of dynamat peel and stick and one layer of 1/4" dynaliner. however i looked up the specs on that liner and NO WHERE do they claim it is intended to dampen anything, dynamat states the liner is intended as thermal barrier only....??

    i have full coverage on the floor of mlv, i want to place it on the back wall as well but i worry its to heavy for the ceiling and doors? if its a night and day difference from an MLV style to the next step down (some type of foam) then ill figure out how to make MLV work, however if its only slightly less effective than MLV but lighter and easier to install then i think id prefer that route.

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  17. Posted

    at the point i asked i already had the spray on, i had also never done it so i wanted to see what it was like first hand.  

    what i noticed was about 1/2 coverage with a single layer of even mesa mat stops the tinny noise when you knock a panel and it makes the noise lower in frequency where as 6 coats of pray on with 100% coverage dosent lower the frequency but does stop the tuning fork style reverb after hitting it. 

     

    so if im understanding correctly the stick on or spray on damping is more of a secondary concern and using absorptive materials will do more for internal cabin noise?  i have used MLV on my floor and rear but i didnt order anything for my doors yet. i have room to do maybe 3/4" on my doors, my understanding is as a general rule the thicker and more dense the better. i have accommodation on dynamat but looking at their dynaliner im not convinced it would be the best type of product for this as it appears to be just foam. if i were to order MLV im honestly not sure how i would secure that to teh roof with out welding studs in there o.O. all i know is i want to use what ever product is best for blocking outside noise and ill just deal with mounting.

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  18. Posted

    i decided to try some spray on deadener as opposed to stick on, i gutted/cleaned my truck before application and applied multiple layers. i found sprayed in a 1/16 inch coat with about 40% overlap a single spray has no effect, two layers is enough to stop reverberation of a smaller 5X15" panel when you tap it with your knuckle and 3+ layers is needed for larger 2X5' areas. however the peel and stick products (dynamat and mesamat in this case) not only stop the reverberation but audible lower the resonance of the panel they are applied to while the spray on does not do this, or at least not to a noticeable level.  i applied 6 coats of spray on for large areas with seemingly no audible change past the 4th layer. 

     

    my question is this: so you stop the reverberation, thats good, but how does lowering the resonance of the panel effect your cabin noise when not coupled with the resonance? basically trying to separate the two effects of sound damping into quantifiable distinctions.

    second, if spray on takes time to dry, time to do multiple coats, a fair amount more prep work than peel and stick... what are its advantages? why would one choose to use spray on over peel and stick?

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  20. Posted

    we sell many dsp's that are quite expensive and listed to go from 10hz-67Khz, 96khz 24bit or even as high as 192khz... im questioning what is actually needed to get good quality audio.

     

    as far as i know you need double hte sampling rate of the frequency you are reproducing to get the same output as input. now my understanding is the output is EXACTLY what is put in at double the sampling rate. (i suppose minus a bit of dithering?)  so if a file was 20hz-16khz a sampling rate of 32khz would be able to accurately produce every sine wave in that file.... right?

     

    then we have the amplitude, my understanding is 16bit is enough to give +/- 100db of dynamic range which seems WAY more than is needed to me? i mean if im blasting my stereo i doubt i could hear subtle audio at even 50db less than im playing it as my EARS cant adjust fast enough for that kind of gradient.

     

    some of the processors in these dsp's are 64 bit now, isnt a 24bit or even a 16bit processor enough to handle the standard 44.1/16 cd audio?

     

    wich brings me to the next question...i can tell the difference from an mp3 to a flac or a 96kbps mp3 vs a 320mp3 but i cant hear any difference in a wav vs a flac, i have taken flac files from HD tracks and down converted them to wav and i just cant tell... i "think" a wav file is 22.5 khz for each channel right? so a 48khz sampling on a dsp should be more than enough to not induce any distortion?

     

    i have also read that super-sampling a wav file will lead to artifacts, such as if you sample a 44.1 wav file to 192 it will have more audible distortion than that same file sampled at 48.  does a dsp function differently than the raw audio playback file does? does it need more data points to do its job or is all this higher sampling/higher bit rate/fancy cpu's all marketing? 

     

    finally IF all this higher sampling/bit/cpu all does generate higher fidelity audio... is that increased clarity going to ever be discernible in a car environment? 

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  21. Posted

    i like the idea of a carputer but i dont want to deal with a UI mess. ive been looking at available software but idk. i dont really care for any of the current double dinn name brand setups and the android chinesiums have some kool features but their hardware sucks and UI is a mess.

     

    if i could put a 12" touch screen with a UI that defaults to "car stuff" and maybe has secondary apps but every radio setup i have seen so far is the windows or linux or android os with their corresponding apps you need to load and move through. its just not as seamless as a kenwood or pioneer. 

     

    i wish it could be as functional as my laptop when i need it to be and have the UX of a kenwood when i want it to be. 

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  22. Posted

    just thinking, why do we still use head units? we are taking digital signals from streaming/flac/wave files on a phone or usb stick and converting that to analog just to convert it back to digital at the dsp... are there any head units out there that just go digital to a dsp rather than the extra conversion step?

     

    i was considering a carputer to just do source and dsp all in one via software and a soundcard up front

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  24. Posted

    i feel like you are over read or over complicating? I'm not asking about amperage or wiring sizing or anything like that. rather I'm asking that if in the same way you can get grounding differential that can cause induced noise in a system by having grounds spaced all over the vehicle could the same thing or does the same thing occur with the power input feeds from the charging system?  e.g. if you have two alternators that deliver power to different points in the system could that cause a difference in voltage potential that could cause erroneous functionality in either the charging or electrical system?

    rather is there a "standard" practice for multiple charging systems to be routed to a single point or is it acceptable to have them connected to different batteries in the system.

     

    it makes sense to me that routing one alt to the other and then to one battery would be the best way to run the wire but ive never looked into this so i thought id ask

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