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Author Topic: SpeakerPower Torpedo SP1-4000 Plate Amp Review  (Read 7673 times)

Art Welter

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SpeakerPower Torpedo SP1-4000 Plate Amp Review
« on: April 20, 2011, 01:37:47 pm »

Brian Oppegaard, President of SpeakerPower sent me one of his Torpedo SP1-4000 amps for evaluation. Brian spent 11 years as Director of Engineering at QSC Audio Products, Inc. and seven years in the same capacity at Renkus-Heinz before starting Speaker Power in 2002.

SpeakerPower has a wide variety of “plate” amps for use in powered speakers.
The SP1-4000 is presently their most powerful amp, and the first amp in which the company makes every circuit board used.

http://www.speakerpower.net/

The amp is rated 4000W/2 ohm, 2400W/4, 1300W/8, it weighs only 7 lbs.
 Front panel has one input, a balanced XLR input with a  looping XLR output.
One detented volume control, two push switches,  one selects full range response or a 30-80 Hz sub filter, the other a polarity reversal.
A Powercon locking AC input, and a Speakon locking looping speaker output complete the “user interface”. The internal speakers are connected with a latching polarized six pin connector.

The amp itself takes up very little internal volume in a speaker cabinet, and produces almost no heat, critical features for a powered speaker amplifier.

When compared to  other amps, the  lack of heat produced by the 90-95%  efficient  SP-4000 was striking. The cool operation also uses less power  from the AC power service, very important when using the amp with marginal power. More power delivered to the speakers with less from the wall is not only green, but louder!

So how loud does it go, how does it sound ?

Sounds just like the signal going in, until the clip light goes on. Even after the clip light goes on, very little change in sound quality, the clip light is tied to a very fast limiter. Pushing the amp another 6 dB harder after the clip light illuminates, little harsh clipping sound was generated.
This could actually be a problem for some users who will crank the input until high average power smokes the speakers, since there is very little audible tell tale clipping sound.

The SP1-4000 has enough power to cause thermal compression with a pair of Eminence Lab 12 six ohm speakers in a matter of minutes using band limited pink noise run just up to clip. Speaker tests were done with both horn and bass reflex cabinets.
Pink noise has a crest factor of 12 dB, more than some heavy duty compressed dance music, users may exceed the average level of pink noise.
The amp did not heat up even with a nominal 1.5 ohm load, but the speakers sure did!
Without some external limiting to keep average power in check, the SP1-4000 does have enough juice to burn speakers in the 400-700 watt continuous range.

So the amp was able to make the Eminence Lab 12s and a 4015LF sound distressed when hit hard, what about  “big gun” speakers?

Just about the time the amp arrived for evaluation I was testing new cabinet designs for the B&C BC18SW115-4, a four ohm 18 inch speaker that handles 1500 watts with around 15 mm Xmax.

I used the SP-4000 for much of the speaker testing, it was nice to not have a noisy fan blowing heat into the shop while the speaker was getting the equivalent power of a space heater.

The BC18SW115-4 speaker could probably take every watt the  amp could produce without a strain, so from a “bullet proof” powered speaker application, the amp would be a good choice.
That said, for operators that wish to take advantage of the huge peak potential of the latest crop of super speakers, more power could be used.

Brian is working on an export/high mains voltage version of the SP1-4000 which will do 110 V in to 2 ohms, 6000 watts, using a buck regulator to reduce 180-240 VAC mains to a 190 VDC rail for the amplifier. The SP-4000 has a 170 VDC nominal rail.

Power of the high mains voltage version will be approximately 2000W/8, 4000W/4, 6000W/2. The 2 ohm number is tentative and depends on AC line voltage and quality.

This will also apply to the SP1-2400. At higher mains voltages it will do 2000W/8 4000W/4, but no 2 ohm rating.

Brian is also kicking around the idea of doing a 100-120VAC boost regulator version which will do the same numbers.

He asked me if people will pay the extra $100 or so for the higher power.
I can only answer for myself, if using speakers in the power range of the BC18SW115-4, definitely yes.

Having looked at trends in speakers and amps as they chase each other’s power ratings for almost four decades now, I think the new crop of speakers that can handle 1500 (real) watts and peaks of 3 to 6K will only grow larger, a super power plate amp will be welcome.

Using music and pink noise I tested the SP-4000 against all the amps in house, a Crest CC2800, a Crest CA-9, an old Crown PSA 2 (weighs 8 times more than the SP-4000 !) and a QSC PLX-3602.

All the rack amps are capable of 4 ohm bridged mono operation, so a single four ohm load was used.

With music and pink noise into a BC18SW115-4 loaded bass reflex speaker,  the Torpedo equaled the SPL output of the CA-9 and the PLX 3602 (though one 3602 died during testing) put out about 4 dB more than the PSA 2, and 5 dB more than the CC-2800.

Notably, when the SP1-4000 was loaded at two ohms, (one speaker and a dummy load) the speaker level only dropped by 1 dB. 
None of the other amps could put out as much level as the SP-4000 driving two four ohm loads.
As it stands, the SP1-4000 is the highest power commercially available direct sale plate amp I know of.

Art Welter
« Last Edit: April 20, 2011, 07:50:38 pm by Art Welter »
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Josh Duke

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #1 on: May 20, 2011, 03:43:33 pm »

Thanks for the review, Art.  These look like just the thing for the BFM boxes I intend to build.

I have a quick question, though. 

Quote
The amp is rated 4000W/2 ohm, 2400W/4, 1300W/8

Assuming we are not talking continuous power, is that rating program or peak?

Thanks.
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Ivan Beaver

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #2 on: May 20, 2011, 06:37:03 pm »

Thanks for the review, Art.  These look like just the thing for the BFM boxes I intend to build.

I have a quick question, though. 

Assuming we are not talking continuous power, is that rating program or peak?

Thanks.
You cannot pull enough continuous power from a standard 120V wall outlet to be able to deliver that much power continuously.  So it is a peak rating.

I have not had time to measure the specifics of how long it can deliver a sine wave.

But most amps of that type power cannot deliver their power continuously anyway.

It was stated many years ago (I forgot who)that what we really need is a 100 watt amp that will deliver 10,000 watt peaks.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Brian Oppegaard

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #3 on: May 21, 2011, 07:41:50 pm »

Thanks for the review, Art.  These look like just the thing for the BFM boxes I intend to build.

I have a quick question, though. 

Assuming we are not talking continuous power, is that rating program or peak?

Thanks.

Depends on your definition of continuous, program and peak. The SP1-4000 is usually limited by what power is available from the AC mains. Fortunately, breakers can deliver several times their rated current for short periods of time. On a 20A breaker, the SP1-4000 amp will deliver full sine wave power for a couple of seconds before the breaker opens. Musically, that is a long time. The breaker on the faceplate has recently been increased to 30A because some of these new super sub drivers have very low DC resistance, as low as 4.7 ohms for a nominal 8 ohm driver. When driving 4 of these in parallel, the current requirement is quite high. And with modern music styles like dubstep, the crest factor is very low. Amps which are perfectly fine for full range may come up short on sub duty. This amp is designed specifically for this kind of work. It can put out gobs of power. Whether you need a 20A or 30A circuit depends on how you use it.
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Brian Oppegaard
SpeakerPower Inc.
www.speakerpower.net

Art Welter

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #4 on: May 25, 2011, 01:37:17 pm »

Thanks for the review, Art.  These look like just the thing for the BFM boxes I intend to build.

I have a quick question, though. 

Assuming we are not talking continuous power, is that rating program or peak?

Thanks.
You cannot pull enough continuous power from a standard 120V wall outlet to be able to deliver that much power continuously.  So it is a peak rating.

I have not had time to measure the specifics of how long it can deliver a sine wave.

But most amps of that type power cannot deliver their power continuously anyway.

It was stated many years ago (I forgot who)that what we really need is a 100 watt amp that will deliver 10,000 watt peaks.
Ivan,

As Brian says, “continuous” or “peak” are relative terms.

In my  sine wave testing, the  SP1-4000    drew 18.72 amps delivering 83 volts of 30 Hz sine wave into 4 ohms.
At 2 ohms, it drew 30.6 amps and delivered 73 V before the breaker popped after a few seconds.    The mains power in my shop was “browned out” to only 106 volts AC when drawing that much power, I have no doubt the amp could deliver it’s rated voltage with a larger breaker and a stiff AC power source.

When doing the high power sine wave tests at various frequencies (30, 60, 120 Hz) it was striking how the SP1-4000 produced no noticeable heat, while  the other amps belched out heat like a blow drier.

I had not put these figures in the review, as the low voltage in my shop resulted in less than rated power for all the amps.
It is interesting to note the real world conditions though, the 120V power in my shop travels about 100 feet from the main panel through10 gauge. The mains are fed with #4, only about 50 feet from the transformer. Perhaps not as good as some proper portable power distribution systems, but better than what we see in most 120 Volt wiring.
With a 30 Hz sine wave the PLX-3602 (rated 3600 watts into 4 ohm bridged mono) delivered 1640 watts, the SP1-4000, rated for 2400 watts 4 ohm, delivered 1722 watts. The QSC  delivered less than 1/2 power (-3 dB) while the SP1-4000 only dropped a little over 1 dB under the brownout condition.

Of course, sine wave testing is pretty extreme in duty cycle compared to most music.
Using pink noise band limited from 20-80 Hz the shop voltage averaged 116 volts at 2 ohms (17.43 amp draw) when the clip light was just illuminating on peaks.
This would suggest that for “industrial strength” music a 20 amp (or 30 as Brian mentions) breaker should be dedicated to the amp for 2 ohm use.

Art Welter
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Brian Oppegaard

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Alan Sledzieski

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #6 on: July 09, 2011, 10:11:01 am »


Using music and pink noise I tested the SP-4000 against all the amps in house, a Crest CC2800, a Crest CA-9, an old Crown PSA 2 (weighs 8 times more than the SP-4000 !) and a QSC PLX-3602.

All the rack amps are capable of 4 ohm bridged mono operation, so a single four ohm load was used.

With music and pink noise into a BC18SW115-4 loaded bass reflex speaker,  the Torpedo equaled the SPL output of the CA-9 and the PLX 3602 (though one 3602 died during testing) put out about 4 dB more than the PSA 2, and 5 dB more than the CC-2800.


Art Welter

So a ca 9 at 1800w and a 3602 at 3600w were equal in spl?
A cc2800 at 2800w was -5db.
Am I safe to assume the way this was done, if you did a test of a ca9 at 1800w against a cc 2800 at 2800w.  The ca9 would be +5db louder then a cc 2800 at both amps clipping?

Guess what I'm getting at is a ca9 that much better then a cc2800 in head to head bridged mode?
« Last Edit: July 09, 2011, 10:15:53 am by Alan Sledzieski »
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Art Welter

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #7 on: July 09, 2011, 02:14:49 pm »


Using music and pink noise I tested the SP-4000 against all the amps in house, a Crest CC2800, a Crest CA-9, an old Crown PSA 2 (weighs 8 times more than the SP-4000 !) and a QSC PLX-3602.

All the rack amps are capable of 4 ohm bridged mono operation, so a single four ohm load was used.

With music and pink noise into a BC18SW115-4 loaded bass reflex speaker,  the Torpedo equaled the SPL output of the CA-9 and the PLX 3602 (though one 3602 died during testing) put out about 4 dB more than the PSA 2, and 5 dB more than the CC-2800.


Art Welter

So a ca 9 at 1800w and a 3602 at 3600w were equal in spl?
A cc2800 at 2800w was -5db.
Am I safe to assume the way this was done, if you did a test of a ca9 at 1800w against a cc 2800 at 2800w.  The ca9 would be +5db louder then a cc 2800 at both amps clipping?

Guess what I'm getting at is a ca9 that much better then a cc2800 in head to head bridged mode?
Yes, I have found The  CA-9  much better then a CC-2800 in head to head bridged mode.
In fact, I found a bridged CA-6 to have more musical output than the CC-2800 . I have used Crest amps since 1981, the CC-2800 is just not one of their better amps.

A while back  tried out the SP1-4000 on a pair of small 2x10"  tapped horn subs that I had built before acquiring the SP1-4000.

I had previously used the Crest CC-2800  when listening to them (four ohm stereo), at clip the speakers sounded like they were at the end stops. I was rather disappointed with the design, and had not listened to them for a while.

Turns out it was  the CC-2800 giving up, not the speakers. With the SP1-4000 driving them, got almost 6 dB more output, and the speakers sounded better (cleaner) 6 dB louder than the other amp did!

My listening tests were done outdoors, the amplifiers all powered from the same circuit, which has about 100 feet of ten gauge wire between the main service and the outlet.

As it turns out, though my power is better than what I find at most venues, the curcuit still dropped in voltage enough to keep any of the amps from putting out their full power. The SP1-4000, being the most efficient amp, also fares best when voltage drops from a solid 120V.

The way amplifiers actually perform in the real world for sub use can be a far cry from what the specs indicate.
And the way an amp sounds when it clips or current limits is never detailed in specs, the CC-2800 sounds good until the clip/limit lights go on, then almost instantly sounds bad, quite different from the “old school” CA-9 and even older school PSA-2.

By the way, even though  CA-9  betters the PLX 3602 for sub use, above 100 Hz the PLX 3602 beats the CA-9 by a good margin.

The Torpedo SP1-4000 could be driven further above clip than any of the other amps I tested while still sounding good .

It is now my "go to" amp for testing subs.

Art Welter
« Last Edit: May 20, 2013, 07:45:29 pm by Art Welter »
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Alan Sledzieski

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #8 on: July 09, 2011, 02:42:42 pm »

So a ca 9 at 1800w and a 3602 at 3600w were equal in spl?
A cc2800 at 2800w was -5db.
Am I safe to assume the way this was done, if you did a test of a ca9 at 1800w against a cc 2800 at 2800w.  The ca9 would be +5db louder then a cc 2800 at both amps clipping?

Guess what I'm getting at is a ca9 that much better then a cc2800 in head to head bridged mode?

Yes, I have found The  CA-9  much better then a CC-2800 in head to head bridged mode.
In fact, I found a bridged CA-6 to have more musical output than the CC-2800 . I have used Crest amps since 1981, the CC-2800 is just not one of their better amps.

A while back  tried out the SP1-4000 on a pair of small 2x10"  tapped horn subs that I had built before acquiring the SP1-4000.

I had previously used the Crest CC-2800  when listening to them (four ohm stereo), at clip the speakers sounded like they were at the end stops. I was rather disappointed with the design, and had not listened to them for a while.

Turns out it was  the CC-2800 giving up, not the speakers. With the SP1-4000 driving them, got almost 6 dB more output, and the speakers sounded better (cleaner) 6 dB louder than the other amp did!

My listening tests were done outdoors, the amplifiers all powered from the same circuit, which has about 100 feet of ten gauge wire between the main service and the outlet.

As it turns out, though my power is better than what I find at most venues, the curcuit still dropped in voltage enough to keep any of the amps from putting out their full power. The SP1-4000, being the most efficient amp, also fares best when voltage drops from a solid 120V.

The way amplifiers actually perform in the real world for sub use can be a far cry from what the specs indicate.
And the way an amp sounds when it clips or current limits is never detailed in specs, the CC-2800 sounds good until the clip/limit lights go on, then almost instantly sounds bad, quite different from the “old school” CA-9 and even older school PSA-2.

By the way, even though  CA-9  betters the PLO 3602 for sub use, above 100 Hz the PLO 3602 beats the CA-9 by a good margin.

The Torpedo SP1-4000 could be driven further above clip than any of the other amps I tested while still sounding good .


It is now my "go to" amp for testing subs.

Art Welter

Thanks for the info.  I to have been using ca9's for a while.  Tried a pro 8200 in stereo one day on my 4733's it fell on its face, put the ca9 at 500w less aside back on the 4733's and all was good again.
 I'm looking for about 2800w a side to bi amp the 4733's, was thinking of 2 2800's bridged, but after I saw this I'll throw that idea in the garbage.  Crest is no longer crest, they just keep proving it.

What makes the plx so much better then the ca9's above 100 hz?


Thanks again
Al
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Art Welter

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Re: SpeakerPower Torpedo SP1-4000 Plate Amp Review
« Reply #9 on: July 10, 2011, 03:00:01 pm »

Thanks for the info.  I to have been using ca9's for a while.  Tried a pro 8200 in stereo one day on my 4733's it fell on its face, put the ca9 at 500w less aside back on the 4733's and all was good again.
 I'm looking for about 2800w a side to bi amp the 4733's, was thinking of 2 2800's bridged, but after I saw this I'll throw that idea in the garbage.  Crest is no longer crest, they just keep proving it.

What makes the plx so much better then the ca9's above 100 hz?


Thanks again
Al
I am running about a 2.3 ohm load for the mids in my system, the QSC PLX-3602 works well with that load above 100 Hz, while the current limiting in the Crest CA-9 seems to “choke” a bit with that load.

For whatever reason, the opposite is true down low.

The net effect is that even though the PLX-3602 is only rated for about 3 dB more power than the CA-9, it ends up sounding comparatively louder than that for mid/ high headroom.

Given proper 120 volt ac, all the amps I have mentioned will meet their rated specifications on the bench.
Other than differences in storage capacity,  and different limiting approaches, I don’t know enough about amp design to give any technical reasons as to why one amp may be better than another for different usages.

My reply #4  goes into some differences under brownout conditions, all too common in the weekend warrior world, and more common even in “pro” power distribution than most would like to admit.

I had subscribed to the “heavy iron” makes better bass opinion, but at only 7 pounds, Brian Oppegaard’s Torpedo SP1-4000, designed specifically for musical  low frequency,  blows that concept out of the water.

That said, lightweight amps still need heavy cable on the AC side to deliver full output, though the SP1-4000 reduces that  dependence too.

I'll never again buy an amp based only on specifications.

Art Welter
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