lukeamdman

I have the same 5210 surrounds and I really like them.

My buddy always used a pair of DMM for this and now I know why I basically copied his setup for testing current, but he used a 1ohm resistor since he never needed to send more than a volt through the setup. I'll be sending more power through hence the much lower resistance of 0.01ohm.

I tested this using multi-meters before trying it on the scope, but I didn't anticipate the same ground from all the probes (a "duh!" moment after thinking about it for a few minutes). Oh well, you live and you learn. I of course started slow with the scope and it was obvious there were issues before even reaching a single volt, so no harm done. I was really hoping to use the scope for this since it has nice graphs for the voltage history and it's easy to take a screen shot, but that won't be happening. I suppose I can still use the scope to see how accurate the clip lights are on the amps.

I think the issue is that all of the channels have the same common ground. If that's the case, I doubt your scope is going to behave any differently unfortunately. I tried just using a single probe across the resistor and that also doesn't give accurate readings. Additionally, once you approach ~0.75A it starts to severely distort the signal, so much so you can easily hear it in the sub. Next I used a cheater plug on the scope's power plug to bypass the ground. That actually worked for measuring voltage across the resistor! BUT...I still can't use a second probe, so I might have to stick with the multi-meters. I emailed Rigol, so we'll see what they say.

I think I might be having an issue with my scope... Using a pair of multi-meters it all works fine. Using the scope, a 10x probe on channel 1 to measure Vrms directly out of the amp also works fine. However, as soon as I even connect probe #2, the readings for probe #1 are severely reduced. The two probes seem to interfere with each other, and somehow it's actually causing current to run through the probes and heat them up!?!?!

The wiring is correct, so I'm unsure if why I'm having issues. I'm going to double-check everything and try again.

Here's what I threw together today. Amp connects on the left side. The stubby wires on the left make it really easy to connect a 10x probe to measure Vrms.

This wiring diagram, where the leads to measure current are across the resistor, is not correct. When connected this way the current draw on the amp goes through the roof. I'll call my buddy tomorrow to figure out what I'm doing wrong.

I bought this one: http://www.mouser.com/ProductDetail/Vishay-Dale/RH050R0100FE02/?qs=sGAEpiMZZMtbXrIkmrvidDNaDpN5VXc5fz7udgZqacQ%3d 0.01ohm 50W. Should be good for up to ~6kw at 1.5ohm loads. If you need to measure more power than that, the cheapest way is four of these same resistors in a series/parallel configuration for 4x the power handling.

Sweet, the Rigol came with (4) 10x probes. Maybe tomorrow I'll have some time to assemble my resistor jig and try and measure something small.

I just pulled the trigger on the Rigol. It's going to make my head spin learning how to use this thing, but it'll sure be fun!

On that link for the Hantek you posted is says it's a discontinued product? I'll probably go with the Rigol. It's more expensive but it comes with two 10x probes and it's software upgradeable to be a DS1104Z ($850).

It looks like the Hantek is actually rated for a little more voltage with a CAT III rating of 150Vrms. If it can handle that then I doubt 154Vrms for a few seconds would cause it any problems. Or I could always just buy 10x probe and call it a day.

Arggg..... This Hanek and the Rigol are limited to 150v RMS? My testing with the bridged CC5500 exceeded that dang it.

I'm fairly certain I'm going to buy an entry level scope. Maybe the Rigol DS1054Z. Doing this with multi-meters is clumsy and requires longer sine wave durations since I have to keep track of readings on two different displays.

Yes, with the two drivers in each box I'll series the coils and then parallel the drivers. With 4 cabinets, each having a DCR of 1.5ohm, I have good ~2ohm and ~4ohm testing options. For the ~2ohm testing I'll be able to share the load between all 8 drivers.

Good points. The drivers that I will be using for this testing are a dual 2ohm configuration, with each coil having a dcr of 1.5ohm. That being the case, I don't ever expect the resistance to ever drop below that 1.5ohm. I see the worst case scenario between 1.5-2ohm. Good call on measuring the RMS voltage from the amp terminals rather than the sub terminals. This was my plan but I goofed it on my super professional CAD-like diagram.

I was thinking of that as well, but I need/want to keep the resistance at 0.1, 0.01, 0.001, etc so I basically won't have to do any math. 0.08v will equate to 8a, and 0.10v will equate to 10a and so on. I'll know for sure once I test the rig simultaneously with another meter wired in series to compare the results to confirm it's accurate.

Yeah I think you're right. From what my buddy was telling me, most of the time these low impedance wirewound resistors are wound in a way that cancels out inductance anyway even if they don't say it. I'm going to drop down to a 0.01ohm 50w resistor. Even in the worse case scenario of 6kw with a 1ohm load that should be no more than ~40w seen be the resistor. http://www.mouser.com/ProductDetail/Vishay-Dale/RH050R0100FE02/?qs=sGAEpiMZZMtbXrIkmrvidDNaDpN5VXc5fz7udgZqacQ%3d

I'm fairly certain this is how it needs to be wired up, and this looks so good it's scary!

Oh snap, an electrical engineer buddy of mine is onto something. I'll post the details when I understand them, but basically by using a very low resistance wire-wound resistor wired in series with the load, by measuring voltage you're also measuring the current. Here's the resistor he recommended: http://www.mouser.com/ProductDetail/Vishay-Dale/NH050R1000FE02/?qs=sGAEpiMZZMtbXrIkmrvidDNaDpN5VXc5CiNzBrP%252bceM%3d That's the lowest resistance I could find for a non-inductive resistor.

I pulled the trigger on the clamp meter. Should be here tomorrow. I was also looking into a scope and an amp probe, but the probes have the same "accurate" frequency range as the clamp meters. Similar to a simple multi-meter that can be wired in series with the amp/sub (but is limited to 10A), is a there a device that can be used in the same way but can handle loads up to ~80A? My searches have come up empty, but it's very probable I'm searching for the wrong thing since I'm so green to this.

I think I'm going to give this a try: http://www.amazon.com/Fluke-i400-Current-Clamp-Banana/dp/B000EA1ETC/ref=sr_1_1?ie=UTF8&qid=1450396077&sr=8-1&keywords=fluke+i400 The specs say it has a "usable frequency" range" of 5hz-20khz, with the most accurate of that range being 45-400hz. I'll be able to directly compare it with a meter wired in series, so if it's way off I'll know. If this works out, I'd know the resistance of the load at the peak output levels and we'd have a much better idea of actual power being delivered. http://en-us.fluke.com/products/all-accessories/fluke-i400.html#techspecs

I was going to compare the 7.5 to my nu4-6000 (basically a inuke-6k when bridged), but I sold the 7.5 with the Ghorns a couple months back...