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Keystone Sub Using 18, 15, & 12 Inch Speakers
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Old 24th November 2014, 08:47 AM   #411
Osse is offline Osse  Sweden
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Originally Posted by weltersys View Post
My Keystones are loaded with 4 ohm drivers, so I will try one on each bridged mono pair. With four channels each loaded with two ohms, driven to the limit light with 30-100 Hz pink noise it drew up to 11.5 amps (120volt) 100-9000 Hz it rew 9 amps. With 35 Hz sine wave, 21 amps. Long term, the amps breaker would pop, but I was surprised it didn't during the fairly long time I let the sine wave signal go.

Judging by the tests I have already done, it looks like the NU4-6000 is going to be within a dB of amps that cost (and weigh) 2-3 more, and have twice the channels.
I'm sorry about my lack of electrical knowledge, but if I have 230V would it be about half the amperage drawn compared to 120v? It will be interesting to hear your conclusions if the Bridged amp are capable of driving the 115 to full performance.

Thanks
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Old 24th November 2014, 02:04 PM   #412
weltersys is offline weltersys  United States
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Originally Posted by BP1Fanatic View Post
Are just downsizing or are you going to replace the keystones?
Downsizing, selling my largest system complete with the Keystones, retaining a smaller system that has a pair of the new SynTripP cabinets and a pair of 2x15" PPSL subs, that pair of subs are the size of one Keystone.

I still have the Domino DFLH system (powered by some older amplifiers..)with four top cabinets and a nifty little 10" tapped horn for sale (cheap, like less than component cost).

Art
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File Type: jpg Domino DFLH & Tops.jpg (125.5 KB, 494 views)
File Type: png TH10".png (413.3 KB, 491 views)
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Old 24th November 2014, 02:28 PM   #413
Brian Steele is offline Brian Steele  Grenada
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Originally Posted by weltersys View Post
I still have the Domino DFLH system (powered by some older amplifiers..)with four top cabinets and a nifty little 10" tapped horn for sale (cheap, like less than component cost).

Art
A 10" PA TH? Would love to see the design notes on that.
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Old 24th November 2014, 02:52 PM   #414
weltersys is offline weltersys  United States
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Originally Posted by Osse View Post
I'm sorry about my lack of electrical knowledge, but if I have 230V would it be about half the amperage drawn compared to 120v? It will be interesting to hear your conclusions if the Bridged amp are capable of driving the 115 to full performance.
I'll be finishing the amplifier tests today.

120(volts)x21(amperes)=2520 watts. If the NU-4 6000 is 90% efficient (just a guess, I should have measured the output voltage during the sine wave test) it would be putting out 2268 watts/4 channels/2 ohms, about 567 per channel, so a mono bridged pair should do around 1134 watts in to 4 ohms. With sine waves (or certain genres of music that has similar 3 dB crest factor in the sub 100 Hz range), that may be enough power to char a BC18SW115-4 after not too long a time.

The stink from the (over) heated BC18SW115-4 voice coil epoxy lingered in the shop for several days after the last sine wave tests. I did verify all 28 drivers used in the tests are still working perfectly, though upon first listening thought I'd had lost 7 out of 8 HF drivers, fortunately it turned out to be a oxidized connection on the first link cord.

2520 (watts)/230 (volts)=10.96 amps, just over half the amperage needed for 120 volt operations. I envy the European power, I could cut my AC cable weight in half if 230 vac was available from the usual household outlets.

Even though the NU-4 6000 is super efficient, it still sucks power like crazy on peaks, ideally you should size your 230 vac cable for 29 amp (peak) draw with no more than 5% voltage drop for whatever length you are running. At 120 volts, ideally we would size the cable for a 55 amp peak draw!

That size cable is too heavy for me to lug around, so I will live with some voltage drop and reduced peak power output...

Art

Last edited by weltersys; 24th November 2014 at 02:54 PM.
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Old 24th November 2014, 10:05 PM   #415
Osse is offline Osse  Sweden
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Originally Posted by weltersys View Post
I'll be finishing the amplifier tests today.

120(volts)x21(amperes)=2520 watts. If the NU-4 6000 is 90% efficient (just a guess, I should have measured the output voltage during the sine wave test) it would be putting out 2268 watts/4 channels/2 ohms, about 567 per channel, so a mono bridged pair should do around 1134 watts in to 4 ohms. With sine waves (or certain genres of music that has similar 3 dB crest factor in the sub 100 Hz range), that may be enough power to char a BC18SW115-4 after not too long a time.

The stink from the (over) heated BC18SW115-4 voice coil epoxy lingered in the shop for several days after the last sine wave tests. I did verify all 28 drivers used in the tests are still working perfectly, though upon first listening thought I'd had lost 7 out of 8 HF drivers, fortunately it turned out to be a oxidized connection on the first link cord.

2520 (watts)/230 (volts)=10.96 amps, just over half the amperage needed for 120 volt operations. I envy the European power, I could cut my AC cable weight in half if 230 vac was available from the usual household outlets.

Even though the NU-4 6000 is super efficient, it still sucks power like crazy on peaks, ideally you should size your 230 vac cable for 29 amp (peak) draw with no more than 5% voltage drop for whatever length you are running. At 120 volts, ideally we would size the cable for a 55 amp peak draw!

That size cable is too heavy for me to lug around, so I will live with some voltage drop and reduced peak power output...

Art
That's what I was searching for in manuals and such, the capability of the ac inlet of an amp tells a lot about it and in the nu-4 6000 it is 12 ampere in the EU version so it sounds like the power stage and amplifier stage are well optimized for each other. Thanks for your detailed explanation and I'm looking forward to your conclusions in your test!
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Old 25th November 2014, 01:40 PM   #416
BP1Fanatic is offline BP1Fanatic  United States
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A 10" PA TH? Would love to see the design notes on that.
Have you seen the THAM10?
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Old 25th November 2014, 03:46 PM   #417
Brian Steele is offline Brian Steele  Grenada
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Have you seen the THAM10?
Yup. I'd like to see if Art came up with something different.

I did try out a THAM-type fold with a 12" driver. I prefer the SS type fold for a number of reasons.
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Old 25th November 2014, 05:05 PM   #418
BP1Fanatic is offline BP1Fanatic  United States
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What are your reasons?
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Old 25th November 2014, 06:03 PM   #419
Brian Steele is offline Brian Steele  Grenada
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What are your reasons?
1. Panel flex: The larger the panels, the greater the tendency to flex, and the greater the bracing requirements to minimize this. The THAM design places some of the largest panels near the points of greatest pressure (e.g. at S1). In the SS fold, the shortest panels are located at S1.

2. Geometry/Design Flexibility: The THAM design results in a box with a roughly square cross-section if the taper is done properly, and it's not easy to implement a dual-taper design with this fold. The SS fold offers a lot more flexibility wrt dimensions and it's actually quite easy to do a dual-taper design with it.


The THAM fold has one advantage - the area of the box around the mouth is more reinforced than is the case with the SS fold. But this can be addressed in an SS fold if it really is an issue by diagonal cross-bracing across the mouth.
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Old 25th November 2014, 08:22 PM   #420
weltersys is offline weltersys  United States
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Yup. I'd like to see if Art came up with something different.
Different, but similar to the Keystone, you can see it in post #55:

Midbass tapped horns?

The chart below is the response of the 2x10" compared to a JBL SRX 728 dual 18" cabinet, both with 25/125 BW24 filters.
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File Type: png WS 2x10TH.png (146.5 KB, 429 views)
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