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Amplifier Comparison SpeakerPower SP2-12000 and Powersoft K20-DSP-Aesop


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                                       Volts                 Amps                 RMS Power               Peak Power (approximately)

Max Clean:                   86.5V                 71.08A                6148.1W                     8693.4W

 

~1dB into clipping:      88V                    72.31A                6363.28W                   8997.7W

 

 

 

Your outlet power is 122V x 30A =3660W times two breakers is 7320W of total power (RMS) available to your amp.

 

That means that at max clean power your amp is ~84% efficient driving 1.217 ohms.  Not too sure how 2 channel testing would change things, efficiency might go up and power per channel will go down perhaps.

 

Thanks for doing that Luke, good contribution to the thread. That is impressive sustained power @27Hz.  Your driver had to be about at it's mechanical limits?

 

If Brian O. happens to read this post, correct me if I am wrong about any of this and I have a question:  Have you comparison tested your amps using high voltage/high impedance vs. high current/low impedance?  Is there a difference in efficiency or distortion numbers? 

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Your response is disappointing, and you mistake my critical peer review for excessive ego.

I'm not an engineer or a scientist but if I was why would I want you to review anything I did or wrote?  Are you an expert in amplifier design?  Are you here to share your experience in amp testing?  You seem to contribute nothing to this site except an argumentative opposing view.  I'm good on that.  The shit gets old.  Save all of your "help" for someone who wants it, I'll be just fine without your critique. 

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                                       Volts                 Amps                 RMS Power               Peak Power (approximately)

Max Clean:                   86.5V                 71.08A                6148.1W                     8693.4W

 

~1dB into clipping:      88V                    72.31A                6363.28W                   8997.7W

 

 

 

Your outlet power is 122V x 30A =3660W times two breakers is 7320W of total power (RMS) available to your amp.

 

That means that at max clean power your amp is ~84% efficient driving 1.217 ohms.  Not too sure how 2 channel testing would change things, efficiency might go up and power per channel will go down perhaps.

 

While a circuit can sustain far more than its rated current for brief periods of time (as discussed earlier in this thread), the maximum current draw a circuit can sustain indefinitely is actually 80% of its rated load, i.e., 24A on a 30A-nominal circuit.  Either way, you have no way of knowing how much current the amp is drawing from the mains when the amp taps out.  This quantity has to be measured separately.

 

I'm not an engineer or a scientist but if I was why would I want you to review anything I did or wrote?  Are you an expert in amplifier design?  Are you here to share your experience in amp testing?  You seem to contribute nothing to this site except an argumentative opposing view.  I'm good on that.  The shit gets old.  Save all of your "help" for someone who wants it, I'll be just fine without your critique. 

 

I am not an expert in either amplifier design or testing.  That's why it's peer review and not expert review.  You are right that you never asked for my feedback, and it's obvious that you don't appreciate it.  Nevertheless, you and Dave are making statements about this product and about amplifiers in general that are based on calculations or technical reasoning that I know to be faulty.  Many readers here don't have the skill-set to validate these statements.  I'm providing counterpoint to clarify things, and I hope this is of benefit to other readers.  This counterpoint can benefit you and your understanding of amps if you bother to try to understand what I am saying, but apparently you and Dave have other priorities.

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While a circuit can sustain far more than its rated current for brief periods of time (as discussed earlier in this thread), the maximum current draw a circuit can sustain indefinitely is actually 80% of its rated load, i.e., 24A on a 30A-nominal circuit.  Either way, you have no way of knowing how much current the amp is drawing from the mains when the amp taps out.  This quantity has to be measured separately.

 

Yeah, no shit SME but Luke doesn't have access to a lab setup does he?  This is what I'm talking about with your annoying shit.  When are you going to step up and show us how it's done then so we can nit pick the crap out of your data?  Oh yeah never, I forgot that will never happen.  Just more of you flapping the gums.  Thanks for contributing nothing yet again and seriously, fuck off with quoting my posts. 

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                                       Volts                 Amps                 RMS Power               Peak Power (approximately)

Max Clean:                   86.5V                 71.08A                6148.1W                     8693.4W

 

~1dB into clipping:      88V                    72.31A                6363.28W                   8997.7W

 

 

 

Your outlet power is 122V x 30A =3660W times two breakers is 7320W of total power (RMS) available to your amp.

 

That means that at max clean power your amp is ~84% efficient driving 1.217 ohms.  Not too sure how 2 channel testing would change things, efficiency might go up and power per channel will go down perhaps.

 

Thanks for doing that Luke, good contribution to the thread. That is impressive sustained power @27Hz.  Your driver had to be about at it's mechanical limits?

 

If Brian O. happens to read this post, correct me if I am wrong about any of this and I have a question:  Have you comparison tested your amps using high voltage/high impedance vs. high current/low impedance?  Is there a difference in efficiency or distortion numbers? 

 

That definitely wasn't easy on the driver.  I'd say excursion was around 2" peak-to-peak, which is slightly beyond the xmax rating but well within the 80mm xmech.  It was also one of the few times I've put my hand on the motor housing and it was warm.  

 

It would take the meter around a second to show the voltage reading, and I let it go another second or so to make sure the voltage didn't drop.  Even so, ~2 seconds of that is a lot of any single driver to take.

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Yeah, no shit SME but Luke doesn't have access to a lab setup does he?

 

That's not the point!  The point is that the amount of current the amp is drawing from the wall may not be anywhere near the current rating of the circuit, and the efficiency quantity you reported is corresponding flawed.  When I brought this fact to bear in my reply, you responded to me with this followed by a bunch of swearing and pouting.  You ought to just compare me to Hitler so we can all move on.

 

That definitely wasn't easy on the driver.  I'd say excursion was around 2" peak-to-peak, which is slightly beyond the xmax rating but well within the 80mm xmech.  It was also one of the few times I've put my hand on the motor housing and it was warm.  

 

It would take the meter around a second to show the voltage reading, and I let it go another second or so to make sure the voltage didn't drop.  Even so, ~2 seconds of that is a lot of any single driver to take.

 

These numbers suggest that the SP amps can sustain their rated power output for at least a few seconds, and your measurements appear to confirm this, at least with one channel driven.

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Ok guys, just did the same test with both channels driven.

 

I was able to hit the same 86.5v without clipping and registered 139.0db.

 

I then bumped the volume by .5db and registered 91.3v and 139.3db...?  Also, no clipping with this?

 

I then bumped the volume by another .5db and registered 91.3v briefly and it then went back down to 86.5v.  The SPL briefly hit 139.6db but went back down to 139db.  I assume there were clip lights but I only ran the test at this volume once since after this I could smell a little bit of voice coil from the subs if I got right up next to them.

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While a circuit can sustain far more than its rated current for brief periods of time (as discussed earlier in this thread), the maximum current draw a circuit can sustain indefinitely is actually 80% of its rated load, i.e., 24A on a 30A-nominal circuit.

k so that's a max possible total of 5760W with 2 24A sustained circuits.  So since Luke measured 6363.28W max power out of the amp I guess the efficiency is >110%.  :wacko:  What Luke and Josh tested are just things to give us an idea of what's really happening with the amp.  No one said any of these tests are completely accurate and you can sit here and nit pick them all to death because you need a lab full of tools to do get an accurate picture.  Unless you're offering to buy Luke an amp meter or to contribute some data of your own that has to do with this thread, kindly get the fuck up off my nuts. 

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I think it is more likely a current protection circuit because when Josh tested at a higher impedance there was no muting with the same burst/long term tones.

 

 

So a GTG at Beast's?  Woo hoo!  Is Dgage mailing that amp so we can get to the bottom of it finally? 

 

Not sure, but I will have two mariana's there to play with this time. TWO massive 24" subs.

 

 

The DC detection circuit on the outputs is basically a low pass filter that detects a threshold.  It ends up being current/power related so if VLF was tripping it, it would be level dependent.  While not the same circuit, the Dayton SA-1000 rack mount amplifier has the same issue but happens very easily when driving a nominal 4 Ohm load.  Many incorrectly attributed this to some sort of input clipping, including Mr. Chase who never knew why the ones he sold would occasionally go into protection when driving dual woofers.  Changing the time constant and sensitivity of this circuit was part of the many modifications Sandbagger was doing to the SA-1000 amplifier shipped with the MFW-15 Turbo kits.

 

The detail I can't remember is if the amp shutdown at beast's place required cycling the power or if it bounced back on its own?  To the best of my knowledge there isn't any current protection that would cause a cut out, but a few power line conditions could including a GFI condition or over/under Voltage.  With the severe clipping this level occurred at, it's possible there was some internal condition the monitoring circuits were over-sensitive to as well.  We should also remember the levels the amp cut out at was akin to complaining about how a driver behaves well past linear Xmax.  It's much preferred if any protection doesn't cause a shut down that requires a power cycling, but not suffering any damage is just as important.

 

No, it didnt require power cycling. It bounced back after a second on its own. My Crest and peavey do the same thing where I can get one channel to exhibit the same behavior while the other can still power along just fine. 

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Ok guys, just did the same test with both channels driven.

 

I was able to hit the same 86.5v without clipping and registered 139.0db.

 

I then bumped the volume by .5db and registered 91.3v and 139.3db...?  Also, no clipping with this?

 

I then bumped the volume by another .5db and registered 91.3v briefly and it then went back down to 86.5v.  The SPL briefly hit 139.6db but went back down to 139db.  I assume there were clip lights but I only ran the test at this volume once since after this I could smell a little bit of voice coil from the subs if I got right up next to them.

 

Good additional info Luke.  It should be noted that the clip light is intended as an indicator, but the LEDs ramp up their brightness.  When they first start to flicker it is usually just shy of clipping (1-3dB depending on load, power line, and component tolerances) where the first bit of full brightness is right around the clip point.

 

The 6000W modules are a little fuzzier with the clip lights as they have a lot of Voltage headroom, but as time goes on (5-20 seconds) they ramp down to similar long term power as the 4000W.  That Voltage headroom can be seen in the posted 4 & 8 Ohm power ratings of 3400W & 2000W respectively.

 

 

k so that's a max possible total of 5760W with 2 24A sustained circuits.  So since Luke measured 6363.28W max power out of the amp I guess the efficiency is >110%.  :wacko:  What Luke and Josh tested are just things to give us an idea of what's really happening with the amp.  No one said any of these tests are completely accurate and you can sit here and nit pick them all to death because you need a lab full of tools to do get an accurate picture.  Unless you're offering to buy Luke an amp meter or to contribute some data of your own that has to do with this thread, kindly get the fuck up off my nuts. 

 

Power output can certainly be estimated from the info Luke provided, but there's no way to compute any sort of efficiency.  You can get creative with circuit breaker ratings, but it's just creative math and a guess.

 

Breakers are intended to protect against fault conditions and long term overheating of supply wiring.  Wires take some time to heat up, which is why breakers can have a time-variable behavior.  "Long term" for home wiring near a breaker's rating is often on the order of a minute, not a few seconds as we've all discussed and posted about here.  The dynamic load of the subwoofer also can change based on non-linearities in VC heating and changing air loading in the horn at high level.  

 

Luke's anecdotal data point is very useful for real world performance to design around, and less useful for mathematical calculation of power output, power delivered, power drawn from the wall, and certainly not for calculation of actual efficiency.

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...

 

 

...

 

 

Would this work well/accurately to measure amperage draw?  It's compatible with my Fluke 117. 

 

http://www.amazon.com/gp/product/B000EA1ETC?keywords=fluke%20amp&qid=1444928046&ref_=sr_1_3&sr=8-3

 

 

I plan to re-run some of these tests at lower frequencies AND while dividing the load between (8) sealed FTW-21 drivers.

 

If that Fluke clamp works, I'd be able document the resistance of the load while at the threshold of clipping.  That'd definitely give more accurate numbers for power output. 

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Would this work well/accurately to measure amperage draw?  It's compatible with my Fluke 117. 

 

http://www.amazon.com/gp/product/B000EA1ETC?keywords=fluke%20amp&qid=1444928046&ref_=sr_1_3&sr=8-3

 

 

I plan to re-run some of these tests at lower frequencies AND while dividing the load between (8) sealed FTW-21 drivers.

 

If that Fluke clamp works, I'd be able document the resistance of the load while at the threshold of clipping.  That'd definitely give more accurate numbers for power output. 

 

After looking at the specs, it appears to only be accurate down to 45hz.  Dang. 

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Would this work well/accurately to measure amperage draw?  It's compatible with my Fluke 117. 

 

http://www.amazon.com/gp/product/B000EA1ETC?keywords=fluke%20amp&qid=1444928046&ref_=sr_1_3&sr=8-3

 

 

I plan to re-run some of these tests at lower frequencies AND while dividing the load between (8) sealed FTW-21 drivers.

 

If that Fluke clamp works, I'd be able document the resistance of the load while at the threshold of clipping.  That'd definitely give more accurate numbers for power output. 

 

 

After looking at the specs, it appears to only be accurate down to 45hz.  Dang. 

 

I haven't looked at the exact unit and specs yet, but you should be able to get decent info for sine wave testing over shorter duration.  You would have to check if it can look at peak or some sort of sustained maximum current to measure shorter bursts.  I'm not really sure it will give you all that much more info other than being able to see how the amplifiers draw power from the wall at the same output level, which gives you insight into the real world efficiency.  Ironically a couple big pro amps dump a lot of power into cooling fans if the temp gets hot which can significantly affect efficiency of a class D design.  This shouldn't be an issue in home use though.

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I haven't looked at the exact unit and specs yet, but you should be able to get decent info for sine wave testing over shorter duration.  You would have to check if it can look at peak or some sort of sustained maximum current to measure shorter bursts.  I'm not really sure it will give you all that much more info other than being able to see how the amplifiers draw power from the wall at the same output level, which gives you insight into the real world efficiency.  Ironically a couple big pro amps dump a lot of power into cooling fans if the temp gets hot which can significantly affect efficiency of a class D design.  This shouldn't be an issue in home use though.

 

I was more interested in how the resistance changes as the voltage/amperage/excursion also increases.

 

Sure the starting load may be 1.989ohms at a single volt, but will that go up or down once you're at 80v, and by how much?

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The average resistance will go up with more heat in the coil but whether the magnitude at any one frequency goes up or down is not as simple. Once the coil really heats ups or the driver is under a lot of pressure or excursion demands are high the impedance can shift dramatically. You can see this in the power compression tests for a number of systems.

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  • 4 months later...

Saaweet!  Looks like my currently planned build just got a bit cheaper.  And I see that the HT models gained the 12V trigger feature as well.  Very nice!

 

Yeah that's a nice feature!

 

I also see he updated the spec sheets which lists a more accurate frequency response and also power output numbers for the 240v amps running on 120v. 

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Yeah that's a nice feature!

 

I also see he updated the spec sheets which lists a more accurate frequency response and also power output numbers for the 240v amps running on 120v. 

Can you please point me to these updated spec sheets?  I can't seem to find them.

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Thanks!  I couldn't find a the link for that anywhere on the rest of the web site.  It looks like those specs are for the Pro models.  I wonder if there's a specs page specifically for the home theater models?

 

Another bit of information I'm curious about is how many amps are recommended on the circuit to run each amp.  There's a picture of the SP1-4000-HT, which shows "120 V / 8A" on the nameplate.  Unfortunately, the exact same picture appears for the other plate amps, and no similar picture exists for the rack amps.

 

I'll probably have to email about it or something.

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