fr34kout Posted April 11, 2011 Report Share Posted April 11, 2011 Oh and @ 1 ohm it's basically just square root. At a true 1 ohm load, the voltage and amperage coming out of the amp will be the same. So if you set it to 55 volts, it would also put out 55 amps for a total of 3k watts. In reality, the amperage is going to be lower because of box rise, resulting in less power. But you can still use the DMM to pretend to set your gains to the power you want now, and you'll know you're even safer because of box rise. So if you set it for 3k @ 55 volts like you were saying, you could end up with something low like 500 watts if your box rise is crazy and you're seeing something stupid like 5 ohms. Quote Link to comment Share on other sites More sharing options...
REaudioBuff Posted April 11, 2011 Author Report Share Posted April 11, 2011 Ok well not to ask you to straight up teach me everything here but this is making very good sense to me. If i have box rise of lets say 5ohms as you used. How could I set the gains with the dmm... I mean even if i found out the rise of the box with a clamp meter and all how could i set the gain closer to where i want it at 3k rms with the dmm... Sorry if this is annoying you but im learning a great deal here thank you sir Quote 1 Crossfire XS v2 15" 2 Deka group31a's 1 XS Power D3400 (under hood) 1 Addictive Audio 500.1 1 Rockford 3sixty.2 4 Crescendo pwx 6.5s 2 Pyle Pro Super tweets 1 Crescendo 1000c4 Kenwood excelon x494 Head unit Big Three upgrade All 0 gauge of course 1 4.56c^ft box @28hz (New Best official db score= 151.2 @ 36hz) Link to comment Share on other sites More sharing options...
fr34kout Posted April 11, 2011 Report Share Posted April 11, 2011 Basically when you use a clamp meter, it will show you the voltage and amperage coming out of the amp. You would want to start this with the gains set with your DMM if you were to do it this way. Burp a frequency, say 40 hz and clamp the speaker wires coming out of the sub amp. The clamp meter will show you the voltage and amperage coming out of the amp. I'll just do the setting it with a DMM @ 3k example and run with it. If you set the voltage to 55 volts, and your box rise ended up @ 5 ohms, it would show 55 volts and 11 amps. When you multiply the 2 together, you get 605 watts. Now from here, it's not so much as trying to get up to 3k, it's trying to match your output to the amps specs. I'm going to slightly change the example and use my 4500. So say I started off @ 55 volts with my amp, but instead after box rise I was @ 4 ohms. 55 / 4 is 13.75, so the amp would be putting out 55 volts and 13.75 amps. Multiply those 2 together, and you get 756 watts. Now if we go look up the specs of the Sundown, it's rated to do 900 watts @ 4 ohms, so I would want to get my output up to 900 watts. This part might be a little confusing, but this is how you would do that. 900 = 4x(x) with the 4 being your actual load after rise. So then 900 / 4 = 225. Then you want to take the square root of 225 which is 15. You want the amp to put out 15 amps, and since your ohm load is 4 ohms you want the voltage to be 4 times higher. So 15 x 4 = 60, you would set the voltage coming out of the amp to 60 to get 900 watts @ 4 ohms. Quote Link to comment Share on other sites More sharing options...
REaudioBuff Posted April 11, 2011 Author Report Share Posted April 11, 2011 Ok im understanding that much. I'm taking down my little notes off this haha. I love math btw i just don't know the equations thats it. once i see what goes where it looks like #s to me lol. So my real question after this is lets say on your amp then you do set it to that. 60 volts coming out when your doing the gain setting again. Lets say running the system on the 40hz tone like you did you set your amp to 60 volts now does that mean your only gonna see that 900watts??? and if so then why in the world would i want a 5-7krms amp lol i know i gotta be mixed up on something there.. Quote 1 Crossfire XS v2 15" 2 Deka group31a's 1 XS Power D3400 (under hood) 1 Addictive Audio 500.1 1 Rockford 3sixty.2 4 Crescendo pwx 6.5s 2 Pyle Pro Super tweets 1 Crescendo 1000c4 Kenwood excelon x494 Head unit Big Three upgrade All 0 gauge of course 1 4.56c^ft box @28hz (New Best official db score= 151.2 @ 36hz) Link to comment Share on other sites More sharing options...
fr34kout Posted April 11, 2011 Report Share Posted April 11, 2011 Well it lets you set the amp safely until you can actually oscope it. Like I said earlier, I have a 4500 wired @ 1 ohm, but after rise I'm @ 3.67 ohms and only seeing 2600 watts (which is still extremely good for that high of an ohm load). The reason people buy such big amps is to try and get as much power from the get go instead of trying to fight box rise. A lot of people would be surprised if they clamped their amps and saw how much power they were actually getting. Quote Link to comment Share on other sites More sharing options...
REaudioBuff Posted April 11, 2011 Author Report Share Posted April 11, 2011 Lol i guess i dont really need to know how to do all that.. Thanks man it was good learning that right there. I will still prolly see if i can wrap my head around that and use the clamp meter and all. Thanks for the help I feel better about running this amp to this sub now. I'm not too worried about blowing it. I have seriously overpowered subs for a few years now so im used to doing that. I'm smart with how i play them and how long i romp on them for. But this will just help with knowing more about where im actually at on power. thanks again man Quote 1 Crossfire XS v2 15" 2 Deka group31a's 1 XS Power D3400 (under hood) 1 Addictive Audio 500.1 1 Rockford 3sixty.2 4 Crescendo pwx 6.5s 2 Pyle Pro Super tweets 1 Crescendo 1000c4 Kenwood excelon x494 Head unit Big Three upgrade All 0 gauge of course 1 4.56c^ft box @28hz (New Best official db score= 151.2 @ 36hz) Link to comment Share on other sites More sharing options...
TeamHT Posted April 11, 2011 Report Share Posted April 11, 2011 I stopped reading once impedance rise was being used as a suggestion to save your driver. Here's my personal advice...don't count on rise to save you. Especially if it is a daily system...where frequency will change...CONSTANTLY. For the space you have to play with, I would keep the XL and go with a smaller amp. You have some frugal options, an AQ2200...I think skittles might still have a Crescendo 3kw for sale. Quote Tell me...does this smell like chloroform to you? Link to comment Share on other sites More sharing options...
fr34kout Posted April 11, 2011 Report Share Posted April 11, 2011 I'm not saying to count on it to save you, I'm saying that if you are using a DMM to set your gains, your power output is going to be much less than you actually think because of box rise. You may think you're getting a certain amperage out of the amp, but because of rise you will be getting 2-4x less, this of course will change with frequency. Quote Link to comment Share on other sites More sharing options...
REaudioBuff Posted April 11, 2011 Author Report Share Posted April 11, 2011 Well if I were to sell/ trade this amp i would do it for like 2 amps of that power. This is just too massive to do something like a straight trade lol. I think though i will wire it to 4 ohms to break it in for like a week or so. then wire it down and see what im getting... Quote 1 Crossfire XS v2 15" 2 Deka group31a's 1 XS Power D3400 (under hood) 1 Addictive Audio 500.1 1 Rockford 3sixty.2 4 Crescendo pwx 6.5s 2 Pyle Pro Super tweets 1 Crescendo 1000c4 Kenwood excelon x494 Head unit Big Three upgrade All 0 gauge of course 1 4.56c^ft box @28hz (New Best official db score= 151.2 @ 36hz) Link to comment Share on other sites More sharing options...
ChevyBoy95 Posted April 11, 2011 Report Share Posted April 11, 2011 (edited) I stopped reading once impedance rise was being used as a suggestion to save your driver. Here's my personal advice...don't count on rise to save you. Especially if it is a daily system...where frequency will change...CONSTANTLY. For the space you have to play with, I would keep the XL and go with a smaller amp. You have some frugal options, an AQ2200...I think skittles might still have a Crescendo 3kw for sale. i did too. rise is only the same on burps, which is why people calculate it down and wire there amps to .35 because they know after rise it will be at 1(or there desired ohm load). but on music the ohm load constantly changes, quite quickly actually, MUSIC AND IMPEDANCE RISE SHOULD NEVER BE IN THE SAME SENTENCE.(<---except for that one) hook a DMM up to your amps output terminals, put the DMM on ohms, play a song and watch it jump around. makes me want to punch my computer screen when people talk about calculating box rise when they play fucking music on the systems (DDs). /rant Edited April 11, 2011 by ChevyBoy95 Quote Best Score to Date : 160.5 dB Outlaw (47Hz)[4 XM 15's & 2 Taramps Bass 12k's] BL : http://www.stevemeadedesigns.com/board/topic/147800-chevyboy95s-4-15s-7krms-wall-1533-db-on-half-power/YouTube: http://www.youtube.com/hitemwiththeflex/ Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.