Like, lets say i have an amp that can do power down to 1 ohm all day. Let's say it's 1000w rated.
Where would I buy a "resistor" for this at? How do i know what is the right one to buy? How to wire it up? can they hold the power they are recieving for a while to meter it?
posted
ebay is a good place if you want to buy resistors... just get some high powered resistors, 100w or so, plop them on a heat sink, like 5 5 ohm resistors, 4 4 ohm resistors, etc
posted
You can try to find a 1 ohm, 1000+ watt resistor, or you can get say 10 10ohm 100 watt resistors and put them in parallel. It will probably be easier to find the smaller ones than a single bigger one. I have 2 2000 watt resistors, they're about the size of a 1F cap and have curvy fins all around them for heat dissipation, which is a huge issue.
I would look at surplus stores, BGmicro, electronic goldmine and the like. Big resistors are expensive, and getting them surplus will help alot. I bought both of mine for about 40 dollars I think.
Hooking them up is easy, they have 2 terminals, one positive one negative, they aren't polarized so you can't hook it up wrong. Some resistors are variable so there is a third terminal that you could hook up to instead of one of the end terminals.
They can hold the power, as long as they are allowed to dissipate the heat. 1000 watts is a lot of heat, like a small electric space heater. When I'm doing serious long term high power testing I have my resistors mounted on a frame that holds them in the air, and have fans underneath to blow air across them.
Posts: 2575 | From: GA | Registered: May 1999
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posted
Also, if you want to get REAL result, you should use non inductive resistor because normal resistor like you are talking are inductive(made from spire wire) the problem is that impedence change depending of the frequency.. like a coil. Non inductive are made from carbon, ceramic, chemical mixture or coil with spire rolled in both sens to cancel magnetic flux.
That would help you to test your amp with stable impedence, avoiding frequency problem
Doc
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 645 | From: Quebec city | Registered: Mar 2000
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quote:Originally posted by Doctorbass: Also, if you want to get REAL result, you should use non inductive resistor because normal resistor like you are talking are inductive(made from spire wire) the problem is that impedence change depending of the frequency.. like a coil. Non inductive are made from carbon, ceramic, chemical mixture or coil with spire rolled in both sens to cancel magnetic flux.
That would help you to test your amp with stable impedence, avoiding frequency problem
Doc
??? resistor 1 hand, inductor on the other... ??? only thing i can think of that makes any sense with what you are saying is a thermal resistor, which increases its resistence with heat... or vice versa...
Let's say i buy a non inductive resistor, wire it up, turn on stereo, play lets say 40Hz and got the DVM and ammeter handy ready to get readings.
The power going to the resistor is a LOT more than what the resistor is rated for, like the above link- 4 ohm 100w. I metered my amp at doin 676w at 3.55 ohm so i know it does more than 100w at 4 ohm. What is gonna happen to this resistor? It isnt gonna spark or blow up in my face is it if the power output was a lot more than anticipated?
posted
meltdown. it's not going to explode... it's just a coil of wire encased. same as a woofer coil for your example. I've melted a few.
-Nick
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If I showed up to Game 7 of the World Series and was found to have a Corked Bat in pre game warm-ups, what would happen to me? Even if I said that I 'didnt see it in the rulebook, my bad'.
From Finals 2004:
quote:Originally posted by dBSteve: Everybody in the top 8 in every class bent the rules.
posted
shizzzon, just go buy the link i gave you for ebay, it is all you need. $25, for 4 225 2 ohm resistors, no searching or anything. or there are 8 300w 2 ohm resistors on ebay for $60.
quote:Originally posted by Doctorbass: Also, if you want to get REAL result, you should use non inductive resistor because normal resistor like you are talking are inductive(made from spire wire) the problem is that impedence change depending of the frequency.. like a coil. Non inductive are made from carbon, ceramic, chemical mixture or coil with spire rolled in both sens to cancel magnetic flux.
That would help you to test your amp with stable impedence, avoiding frequency problem
Doc
??? resistor 1 hand, inductor on the other... ??? only thing i can think of that makes any sense with what you are saying is a thermal resistor, which increases its resistence with heat... or vice versa...
Jar.. What? A wire wound resistor IS a coil of wire, so obviously it's also an inductor too. Non-inductive resistors have half of the coils clockwise and then a switchover and the other half counterclockwise to cancel the magnetic field.
Obviously with material composition resistors you don't have this problem, but they're usually not available in high power dissipations
ShadowStar
-------------------- You can't build a reputation for what you're GOING to do.. But you can build one for TALKING about it!
It's all about knowledge, love and respect. Posts: 2579 | From: Somewhere In the Northeast | Registered: May 1999
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I'm French.. so i think you explained what better than me what i mean.. (I do my best in english with only the words i know to speak on this forum...)
Doc
-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 645 | From: Quebec city | Registered: Mar 2000
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posted
I'm pretty sure you can drop resistors into distilled or ionized water . One of them is non conductive , BUT I forget which one so double check before doing so . That way they'll stay cooler at power higher than rated for . 30 seconds at a time testing still though ..
quote:Originally posted by mister_B: I'm pretty sure you can drop resistors into distilled or ionized water . One of them is non conductive , BUT I forget which one so double check before doing so . That way they'll stay cooler at power higher than rated for . 30 seconds at a time testing still though ..
1) I hope you mean de-ionized.
Also, I really really don't suggest doing this. If you REALLY want to water cool your resistors, wire them up, wrap the whole thing in Saran Wrap, tape it off, *then* dunk it in distilled water.
ShadowStar
-------------------- You can't build a reputation for what you're GOING to do.. But you can build one for TALKING about it!
It's all about knowledge, love and respect. Posts: 2579 | From: Somewhere In the Northeast | Registered: May 1999
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-------------------- Street A "not legal but not outlaw!" Score in my integra: -152.34 dB 51Hz TL sensor -157,1dB 51Hz AC mic
2005-2006 Street A Champion in Quebec province!
CRAZY TESTs: ||||||THE ONLY 6.5" TO SCORE 168.9dB(TL)OUTLAW IN THE WORLD with 6 Watts.|||||| -Crazy 5.25 Bose sub 1.1cu box: 138.0dB TL mic 55Hz with ONLY 100W ! ---------------------------------- www.teamxmax.com Posts: 645 | From: Quebec city | Registered: Mar 2000
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