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Old 12th October 2012, 05:57 PM   #1781
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Quote:
Originally Posted by mwmkravchenko View Post
It quickly becomes a very expensive enterprise to put together an amplifier that is a true voltage source. Either very large transformers or very robust switching systems, both limited to what can be drawn off of the wall outlets.

It is not an engineering impossibility.

As for the Speaker Power amplifier.

About 3 years ago I did an exhaustive study on available plate amplifiers for a client. At least then Speaker Power was using ICE modules. They were supposed to be changing over to Pascal modules. I don't know that for a fact by the way.
The SP4000 was the first SpeakerPower amp designed and manufactured by SpeakerPower, they make all the circuit boards.

When the SP1-4000 was loaded at two ohms, (one BC18SW115-4 speaker and a 4 ohm resistive load) the speaker output level only dropped by 1 dB compared to the 4 ohm level.

It is very 2 ohm capable, I have used it driving 4 Lab 12 in parallel, a nominal 1.5 ohm load that goes well below the nominal rating at Fb.
It current limits with that type of load to keep from blowing the 20 amp breaker. Brian Oppegard (president of Speaker Power) had mentioned a 240 volt version of the amp which would have more output was in the works several months ago, I have not checked the site recently to see what's up.

I posted a review of the SpeakerPower Torpedo SP1-4000 Plate Amp here:

SpeakerPower Torpedo SP1-4000 Plate Amp Review

Art
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Old 12th October 2012, 10:22 PM   #1782
Mark Kravchenko
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That's impressive Art.

Thanks for the info.

This was not available when I was talking with them in 2009.

I will keep this in mind for further work.
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Old 13th October 2012, 09:59 AM   #1783
AndrewT is online now AndrewT  Scotland
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Quote:
Originally Posted by weltersys View Post
.............. I have used it driving 4 Lab 12 in parallel, a nominal 1.5 ohm load that goes well below the nominal rating at Fb.
It current limits with that type of load to keep from blowing the 20 amp breaker.............
that anecdotal information confirms my suspicion.
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Old 16th October 2012, 03:38 PM   #1784
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Finally got some time to finish up my 2nd SS15... but this time, I built one with corner fillers in the "critical" areas and a bit more extended bracing. I'll tell you what, this one was FAR more difficult to assemble than the original! Maybe I just suck at putting in corner fillers... but some things didn't square up very well and was a real nightmare. Regardless, I got it done, just took a lot more clamping, screwing, pulling, etc. to make it work right. I think my issue was using screws to secure the fillers, or perhaps I didn't get a good 45* angle cut on them... who knows.

Anywho, attached is a pic. I'll be doing a direct comparison as soon as this weekend using REW (computer to Firepod interface to Dayton calibrated mic | high end sound card to xti1002 to subs), my multimeter, my yard, measuring tape, and a good beer. I look forward to the comparison. Whichever one "wins" will get a twin built soon.
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Old 17th October 2012, 07:19 AM   #1785
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beautiful work!
really interested to see the measurements, though I feel I'd build with corner fillers just for added strength and stiffness.
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Old 20th October 2012, 10:12 AM   #1786
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Has anyone who has done extra bracing found more benefit from a side-to-side broomstick brace in the mouth more beneficial than two thin front-to-back bottom braces at the bottom of the mouth?
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Old 21st October 2012, 06:09 PM   #1787
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Quote:
Originally Posted by Don Snyder View Post
I tried to beat Jim's last cabinet, and failed. I did come up with a modification of Anders cabinet scaled up to match the size of Jim's cabinet. It's max
output is down 3dB from Jim's but it goes 5Hz lower.

If you want 40Hz in a single box, it may be your best choice.


Post 158 of this thread.

Any more information on angles and distances for the inner folds to turn this sim into a buildable version? Thanks.
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Old 21st October 2012, 08:41 PM   #1788
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Set everything up yesterday and was ready to measure, but then a storm hit hard and heavy and we had to rush to put everything away... though it never did rain, better safe than sorry. Plus, the winds were strong enough to skew measurements. Luckily, today was wonderful.
I used REW (roomEQwizard) to compare between the two. I set my calibrated mic ~1m away (39 3/8"), used a rat-shack meter on slow/C weighted and tuned in 2.83v @ 60hz. Then, ran REW and calibrated the graph to the output of 100db @ 60hz. Here are the results. All this done on my lawn... I have about an acre of property out of city limits, so it was pretty noise free.

I can say that the extra corner fills and bracing was, as jbell predicted, was definitely not necessary and wouldn't benefit. I'll let you read the graphs to see the difference. From my experience, it was a real pain to do the extra corner fills. Sad to see the extra work put into it not pay off, but happy to build my 3rd and final version to the original, much easier to assemble version of this great design.
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Old 21st October 2012, 08:44 PM   #1789
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The corner fills and bracing are to keep the panels stiff. Maybe not a problem in a cabinet that takes 500-600w RMS. but in one that takes a few KW...I'd say it becomes necessary not optional.
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Old 21st October 2012, 09:02 PM   #1790
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Good clean measurement.

And yes the reflectors are not all that.

Sometimes what is a brilliant idea, does not work out all that brilliantly in real life.
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