lukeamdman

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.

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.

For 10hz maybe 1/2"?

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

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.....

I think they're popular because they're low cost and are one of the only DSPs on the market that let you set PEQ and XO below 20hz without extra workarounds. They also have a frequency response that's pretty much flat to DC. As you've pointed out there are definitely some downsides though. The unbalanced 2x4 lacks voltage headroom, and my balanced 2x4 did have some pretty nasty "thump" when powering on and off. Even that balanced 2x4 would benefit from more voltage headroom. My first 10x10 board was actually missing components on the PCB. The noise floor was even higher and there was some really high frequency noise (above 20khz) that kept the amps signal lights lit up constantly. They did send me a new board, and my only issue with the 10x10 now is the noise floor when trying to full active with high efficiency mains. I've seen the capability and flexibility of using the Motu/JRiver combination from mojave and it's really impressive, but I don't want to rely on running absolutely everything through JRiver.

SME, Sorry, just getting caught up on this thread, but so far your experiences have already answered some questions I had! First, it's too bad the OpenDRC-AN has a loud noise floor. I tried to go full active with a 10x10HD and the noise floor was just too much. I could hear the hiss outside the room! I've been trying to think of how to get that last 1% of performance out of my mains, and I was contemplating FIR EQ, but the OpenDRC-AN has now been scratched off the list... Second, the Motu 16A is on my list to replace the 10x10, but it has some downsides. From what I've gathered, it does have 4 bands of PEQ on both the input and output of each channel (so really 8 total), but it doesn't have low-pass filters? Since you're fully active, how have you been implementing a LPF with the Motu?

Josh, I wonder if my system resonance being right at 40hz was causing some of the voltage oddities at 40hz?

Peavey CS 4080HZ (red) vs. Crest CC4000 (blue)

Peavey 4080 is a beast! Testing done at 20hz.

Today is the day! Getting things setup to test it right now. 4ohm 1ch driven 4ohm both ch driven 8ohm bridge frequency response

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

Why aren't these loaded in PaleHorn's yet?!

I was going to say...try the SP amp I've driven my IPALs to what looked like near 3" peak to peak excursion with a SP2-12000!!

I did successfully test the rig with the resistor on the the ground side, but I ran into the issue again with bridged amps since in that configuration there isn't a "ground level" connection... Besides purchasing a very expensive low voltage differential probe to overcome that, I'll have to stick with the DMMs. The 87V is getting calibrated this week.

ok ok...I'll buy WT2 already! Jeepers

Before I even start anymore testing I'm going to get my 87 calibrated. I don't think it's off or anything, but it'd be nice to have the peace of mind that the numbers are accurate. Lucky for me I have a buddy who works at a machine shop, and he used to work for the calibration company that tests/calibrates all their tools!

I think this post got lost in the mix a few pages back: http://data-bass.ipbhost.com/index.php?/topic/476-lukes-basic-amplifier-tests/?p=12560 I did run voltage tests without any subs connected with both the scope and the Fluke plugged right into the amp to compare the results: As you can see, from 20-120hz the voltage only changes by 0.02v. At 10hz and 5hz you begin to see my signal chain roll-off (Marantz AV7005 + MiniDSP 10x10) which is expected. Here's what I think is going on, and take the SP2-12000 for example: Brian lists the voltage output at 126Vrms, which equates to almost exactly 2,000w at 8ohm (rated power spec for 8ohm). I was able to squeeze 127Vrms at 40hz (5.5ohm)and 131Vrms out of that amp at 20hz (4.5ohm). BOTH of those voltages exceed the spec sheet of that amp, which would also explain the distortion I saw in the wave form. With the XLS, and without any subs connected to the amp, it hits the brakes at ~100-102Vrms. According to Crown's specs, it should be able to reach 111Vrms without any load connected to meet specs (rated at 1,550w at 8ohm). However, my testing lasts for several seconds, so I'm not surprised the Crown falls a bit short (It was only $299 new!!). I'm going to re-test with the Fluke 87V, but additionally, I'm going to list the maximum Vrms the amps will produce at 40/20/10/5hz without any subs connected first. After that, then I'll test with a load connected. And yes, my impedance charts are done 1hz at a time with me imputing the readings into a spreadsheet...I should just buy DATS already!

Josh, I'm seriously jealous of the power cord that came with your SP2-12K... My first SP2-12K came with a 14/3 cable with a NEMA-15 plug (15A)... My second SP2-12K I just received today came with another 14/3 cable, but this time with the L6-20 (20A)... I just ordered another Tripp Lite L6-30 10AWG cable to replace the 14awg like I did with the first amp.

Kind of an impulse buy, but I got a used Fluke 87V off eBay. It has a frequency range of 0.5hz-200khz, so we'll see if it oscillates below 20hz like the 117/115.

The "HT" version looks to have typical controls you'd find on a consumer grade sub amp. Things like gain, crossover, delay, etc. On the "DP" version I think you're limited to just gain knobs for each channel. EDIT: The "HT" version also has the standard 15A plug and RCA inputs. Pictures of each here: http://www.speakerpower.net/rack-mount-models.html

Whole new SP website today.

http://www.speakerpower.net/uploads/4/9/5/7/4957539/spec_sheet_sp_rack_amps_dp.pdf

I completely agree on all counts, but I think with the XLS and SP2 I was hitting the voltage limits. Without any load connected I can only get ~100v out of the XLS, and the spec sheet for the SP2 says ~126v from what I recall, which would explain the clipping I saw on the scope.