andy497 Posted April 19, 2016 Share Posted April 19, 2016 ...but I ran into the issue again with bridged amps since in that configuration there isn't a "ground level" connection... Aw nuts. Yes I suppose bridged would be a problem. It's too bad differential probes are so expensive. Do those flukes have any kind of data out feature? I know my cheapy tekpower does. It's actually pretty decent. I think it captures 10 samples per second if you pick low precision: www.amazon.com/TP9605BT-Cellphone-Connection-Interfaced-Multimeter/dp/B00SGKR9FA Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted May 27, 2016 Author Share Posted May 27, 2016 Received the Smith and Larson WT2 today. Neat! This is certainly a lot easier than doing impedance sweeps one frequency at a time with a pair of DMM! lol Quote Link to comment Share on other sites More sharing options...
Stormwind13 Posted May 28, 2016 Share Posted May 28, 2016 Good, now we can see peavey numbers :-p 1 Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted May 28, 2016 Author Share Posted May 28, 2016 Good, now we can see peavey numbers :-p Today is the day! Getting things setup to test it right now. 4ohm 1ch driven 4ohm both ch driven 8ohm bridge frequency response Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted May 28, 2016 Author Share Posted May 28, 2016 On 5/27/2016 at 11:45 PM, Stormwind13 said: Good, now we can see peavey numbers :-p Peavey 4080 is a beast! Testing done at 20hz. 3 Quote Link to comment Share on other sites More sharing options...
chrapladm Posted May 28, 2016 Share Posted May 28, 2016 Look's pretty good to me. Quote Link to comment Share on other sites More sharing options...
Stormwind13 Posted May 29, 2016 Share Posted May 29, 2016 Great, now I just need something to power with it! Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted June 1, 2016 Author Share Posted June 1, 2016 Josh, I wonder if my system resonance being right at 40hz was causing some of the voltage oddities at 40hz? Quote Link to comment Share on other sites More sharing options...
SME Posted June 1, 2016 Share Posted June 1, 2016 Looking at your previously posted results, you show resistance values of between 5 and 6 ohms at 40 Hz, which is much less than what you show here which is close to 15 ohms. Unless I'm misinterpreting your data, the implication is that the currents you are measuring at the resonance are way higher than they should be. Of course, one should expect some impedance difference in drive level, but I wouldn't expect it to be that far off. Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted June 30, 2016 Author Share Posted June 30, 2016 I've been messing with the scope again this week and I think I (well not really me, but a suggestion from notnyt) found out why the Rigol was reading a little higher votages than the Flukes. Here's what I measured before: Apparently there's a High Resolution setting on the Rigol and that seemed to level the playing field between the scope and flukes. I'm going to to re-test the above numbers and report back. Also, and it's unfortunate, but the 87V doesn't oscillate any less than the Fluke 115/117 at 10hz and 5hz...arggg..... Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 1, 2016 Author Share Posted July 1, 2016 Did some CEA burst tests for the first time. This is on a single channel of a SP2-12K. First I wired all eight 21s into a single 1.5ohm load and ran an impedance sweep in WT2: I did some CEA testing at 10hz (2.36ohm) and 20hz (3.54ohm). 10hz: 290Vpp = 102.5Vrms into 2.36ohm = 4,451w 20hz: And I somehow deleted the first screenshot!?!?!? Anyway, 358Vpp clean with no clip lights 358Vpp = 126.5Vrms into 3.54ohm = 4,520w. Also, the spec sheet for these amps says 127Vrms, so this test seems spot on. I then pushed 0.5db further and got 384Vpp and a brief flicker of the clip light. Sure enough, tiny bit of distortion in the peak of the wave form: 384Vpp = 135.7Vrms into 3.54ohm = 5,201w 1 Quote Link to comment Share on other sites More sharing options...
SME Posted July 1, 2016 Share Posted July 1, 2016 Nice. Hopefully spreading the power out across a lot of drivers helps minimize the impedance changes that occur. How much excursion do you think the drivers were seeing for these tests? Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 1, 2016 Author Share Posted July 1, 2016 Nice. Hopefully spreading the power out across a lot of drivers helps minimize the impedance changes that occur. How much excursion do you think the drivers were seeing for these tests? For 10hz maybe 1/2"? Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 1, 2016 Author Share Posted July 1, 2016 Here's a test notnyt wanted me to run on a channel of the 12k. 20hz at 3.5ohm for 12 seconds: Maintains 356Vpp (125.8Vrms / 4,521w) for the entire 12 seconds... Amp ice cold, fans idle. 1 Quote Link to comment Share on other sites More sharing options...
EndersShadow Posted July 1, 2016 Share Posted July 1, 2016 Luke... does this mean the testing you did with the Crown XLS was flawed? I'm a bit over my head here so wanted to just double check if that was the case. Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 1, 2016 Author Share Posted July 1, 2016 Luke... does this mean the testing you did with the Crown XLS was flawed? I'm a bit over my head here so wanted to just double check if that was the case. Those tests are good. The "High-Resolution" thing did lower the voltage a bit, but for the voltages the XLS was putting it was probably only ~2v. For the CEA burst stuff I just tested, those are the starting resistances, and with a reactive load like my subs the resistance will go up with more power. Think of those CEA numbers as a best case number. Maybe I should get some heater elements and a bucket! That's was nice about a non-reactive load, the impedance doesn't change with frequency. Quote Link to comment Share on other sites More sharing options...
EndersShadow Posted July 1, 2016 Share Posted July 1, 2016 Those tests are good. The "High-Resolution" thing did lower the voltage a bit, but for the voltages the XLS was putting it was probably only ~2v. For the CEA burst stuff I just tested, those are the starting resistances, and with a reactive load like my subs the resistance will go up with more power. Think of those CEA numbers as a best case number. Maybe I should get some heater elements and a bucket! That's was nice about a non-reactive load, the impedance doesn't change with frequency. Ok, thanks. I was mainly making sure the XLS stuff was "close" since your testing somewhat invalidates the whole subsonic filter debate. For the sub I'm building now its ported too so it will need a subsonic filter, but I'm using EQ that would potentially go lower than 20hz Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 1, 2016 Author Share Posted July 1, 2016 Ok, thanks. I was mainly making sure the XLS stuff was "close" since your testing somewhat invalidates the whole subsonic filter debate. For the sub I'm building now its ported too so it will need a subsonic filter, but I'm using EQ that would potentially go lower than 20hz Absolute worst case those XLS numbers may be 45-50w high. Quote Link to comment Share on other sites More sharing options...
Ricci Posted July 1, 2016 Share Posted July 1, 2016 Now you're getting somewhere...WT2 and actual impedance curve FTW. Torpedo amps are high current beasts...Are you going to repeat the tests on your other amps on hand? Quote Link to comment Share on other sites More sharing options...
EndersShadow Posted July 1, 2016 Share Posted July 1, 2016 Absolute worst case those XLS numbers may be 45-50w high. Yeah... since I need 200-400 wpc max @ 8 ohm from the entire amp (ie bridged) I'm not worried.... I am thinking about a 2500 later on to maybe a HST-15 or 18 or some other larger sub in a sealed box trying to enter the depths of ULF but thats likely a pipe dream till my new home pipedream materializes. Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 2, 2016 Author Share Posted July 2, 2016 Now you're getting somewhere...WT2 and actual impedance curve FTW. Torpedo amps are high current beasts...Are you going to repeat the tests on your other amps on hand? I'll definitely test some other amps this way, BUT, I think I'm going to put together a non-reactive load with some heater elements and a bucket first. A CEA burst happens way too fast for me to measure the current across my resistor with a DMM. With a dummy load, since the resistance won't change with frequency or as the power increases (well, not NEARLY as much as a driver will), I won't have to measure the current during the actual testing. Anyone have any input/disagreements with that? Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 2, 2016 Author Share Posted July 2, 2016 Here's an updated comparison between the scope and the flukes now that high resolution is turned on. ' The 87V definitely has less fluctuation than the 117, but at 5hz it's still not great. Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 5, 2016 Author Share Posted July 5, 2016 Just ordered 10 of these: https://www.amazon.com/Camco-Screw--Foldback-Heater-Element/dp/B000PSB3B2/ref=sr_1_1?ie=UTF8&qid=1467741070&sr=8-1&keywords=camco+6000w+240v That should get me to almost exactly 2ohm per channel, which can also be easily converted to a single 4ohm load. Quote Link to comment Share on other sites More sharing options...
SME Posted July 6, 2016 Share Posted July 6, 2016 How much power do you plan to put into one of those? Quote Link to comment Share on other sites More sharing options...
lukeamdman Posted July 6, 2016 Author Share Posted July 6, 2016 How much power do you plan to put into one of those? There will be 5 per channel, so the most power one should see is about 1,200w for 4-5 seconds. They'll be in a 5 gallon bucket of water as well. Quote Link to comment Share on other sites More sharing options...
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