SI 18 D4 Linkwitz!

I don't have the time, space, or equipment to make the box myself so I hired a professional box builder to make it for me :bigsmile: Here are his pics, construction is mostly complete sans the driver cutout and finishing. The finish will be black Duratex, which has a nice texture to it. His techniques and attention to detail are impossible to beat for the price, I won't advertise his company name per forum rules but anyone in the area who's interested let me know in a PM.

Thanks.

Here are some more plots, with and without the Linkwitz Transform enabled and with power adjusted accordingly. It seems like 1000-1200W would be a good range to set the limiter on the inuke DSP.

The driver shows up tomorrow, I plan to run some break-in noise on it and then measure it's true T/S params with my WT3. The box is also almost finished. Amp, fan, and heatsinks show up next week :bigsmile:

Here's a wacky approach using a wide PEQ band and the Linkwitz to flatten the overall response further, f3: 23Hz, -6dB at 17.5Hz and -10dB at 13Hz! :dumbcrazy: I don't know if I will try it or not, just an idea. The flexibility of the DSP makes it all too easy to whip up.

Decided on 18-5/8" for the recess cutout after measuring the driver with gasket. The fan and heatsinks for the NU3000dsp also showed up today.

The specs of the NU3000dsp are just right for the SI 18, or pair of SI 18s, especially considering confirmed bench test ratings. Killing an amp trying to get a max SPL rating with a 10Hz sine wave isn't really a representative test of HT or music use :duh: The price is right so hopefully it does me well!

Here are the T/S results of my 18 D4 using WT3/DATS after running a break-in tone all day, series and parallel. Didn't go to the trouble of measuring Vas.

fusseli said:

The specs of the NU3000dsp are just right for the SI 18, or pair of SI 18s, especially considering confirmed bench test ratings. Killing an amp trying to get a max SPL rating with a 10Hz sine wave isn't really a representative test of HT or music use :duh: The price is right so hopefully it does me well!

Here are the T/S results of my 18 D4 using WT3/DATS after running a break-in tone all day, series and parallel. Didn't go to the trouble of measuring Vas.

Click to expand...

Well lets be honest, the iNuke 3000 puts out nowhere near 3000 Watts bridged and certainly a lot less between 10 and 20 Hz...Nope...does not happen. It will surely be fine for the SI's but as I mentioned in the post, the PSI subs mentioned above are a different story. I'm sorry but the iNuke is just not an amplifier that can be driven hard, at least compared to other more robust offerings. I do sine wave testing to find the limits of the driver and the amp and if the sub shuts it down under testing then its a no go, plain and simple. Yes, done long enough a sine will eventually shut down any amplifier but not after less than ten seconds. The ep2500 survived many sine tests without bother.

http://www.diyaudio.com/forums/class-d/213071-behringer-inuke-nu3000-measurements.html

For HT sub use it would be useful to know what it is at 20 or better yet, 10 Hz.
Out of curiosity, I tested voltage and continuous power output for 20hz & 10Hz.

With no load:
20Hz = 49Vrms
10Hz = 44Vrms

With 8 ohm load:
20Hz = 282 Wrms
10Hz = 230 Wrms

With 4 ohm load:
20Hz = 475 Wrms (< 10 seconds)

After about 10 seconds, the power output dropped back to 280Wrms.
Based on this, I skipped the 10Hz and 2ohm testing.

kramskoi said:

Well lets be honest, the iNuke 3000 puts out nowhere near 3000 Watts bridged and certainly a lot less between 10 and 20 Hz...Nope...does not happen. It will surely be fine for the SI's but as I mentioned in the post, the PSI subs mentioned above are a different story. I'm sorry but the iNuke is just not an amplifier that can be driven hard, at least compared to other more robust offerings. I do sine wave testing to find the limits of the driver and the amp and if the sub shuts it down under testing then its a no go, plain and simple. Yes, done long enough a sine will eventually shut down any amplifier but not after less than ten seconds. The ep2500 survived many sine tests without bother.

http://www.diyaudio.com/forums/class-d/213071-behringer-inuke-nu3000-measurements.html

For HT sub use it would be useful to know what it is at 20 or better yet, 10 Hz.
Out of curiosity, I tested voltage and continuous power output for 20hz & 10Hz.

With no load:
20Hz = 49Vrms
10Hz = 44Vrms

With 8 ohm load:
20Hz = 282 Wrms
10Hz = 230 Wrms

With 4 ohm load:
20Hz = 475 Wrms (< 10 seconds)

After about 10 seconds, the power output dropped back to 280Wrms.
Based on this, I skipped the 10Hz and 2ohm testing.

Click to expand...

Here's what I reference for the NU3000, which is plenty based on my simulations:
Peak power 20ms/1000Hz
8 Ohm 2x465
4 Ohm 2x870
2 Ohm 2x1700
RMS (sine wave)
8 Ohm 2x312
4 Ohm 2x600 (2x375 after 3 seconds)
2 Ohm 2x1176 (2x750 after 1 second, protect after 5 seconds)

For the SI 18 D4 a limit of 1700W burst, 1200W for 3sec, or 750W sustained is just right. With the LT (25-30Hz fc) in place the only time the amp will ever be asked for more than a few hundred watts is below 20Hz, which is fairly infrequent in real world HT. In other words it would take some ridiculous volume levels of looping the depth charge scene in U-571, or something silly like trying to max 10Hz SPL with a sinusoid, to ever get near the amp's power limits. Real world signal content, HT or music, is nothing like a sustained sinusoid. Also keep in mind that the 600W rating is the general recommendation by SI for mechanical limits, not thermal. From the bench test and modeling, the NU3000 should be fine for running two SI 18 D4s. If someone is really concerned about overdriving the amp they could consider an NU3000 for a single 18D2, or an NU6000 for a pair of D4s.

Feel free to direct future discussion of the NU3000 to the proper iNuke thread.

fusseli said:

Here's what I reference for the NU3000, which is plenty based on my simulations:
Peak power 20ms/1000Hz
8 Ohm 2x465
4 Ohm 2x870
2 Ohm 2x1700
RMS (sine wave)
8 Ohm 2x312
4 Ohm 2x600 (2x375 after 3 seconds)
2 Ohm 2x1176 (2x750 after 1 second, protect after 5 seconds)

For the SI 18 D4 a limit of 1700W burst, 1200W for 3sec, or 750W sustained is just right. With the LT (25-30Hz fc) in place the only time the amp will ever be asked for more than a few hundred watts is below 20Hz, which is fairly infrequent in real world HT. In other words it would take some ridiculous volume levels of looping the depth charge scene in U-571, or something silly like trying to max 10Hz SPL with a sinusoid, to ever get near the amp's power limits. Real world signal content, HT or music, is nothing like a sustained sinusoid. Also keep in mind that the 600W rating is the general recommendation by SI for mechanical limits, not thermal. From the bench test and modeling, the NU3000 should be fine for running two SI 18 D4s. If someone is really concerned about overdriving the amp they could consider an NU3000 for a single 18D2, or an NU6000 for a pair of D4s.

Feel free to direct future discussion of the NU3000 to the proper iNuke thread.

Click to expand...

First, apologies for derailing your thread but I was responding to the gentleman above [spur31] and the PSI subs, which are quite different from SI's. The iNuke was bench-tested in the thread I posted. I have no quarrel with the mechanical/thermal qualities of the SI driver, I do however have issues with its distortion.

The German test does not really note the frequency of the sine waves used and the link is broken. The stateside testing from DIYAudio noted the frequency at which the amplifier was "run through". Given the results, it is hard to trust this amp with purely resistive loads and my personal experience seals the deal.

You keep referencing sine-wave testing in overtly pejorative fashion but it is used to find limits [Data-Bass.com] and assess the veracity of claims made by manufacturers. You are correct about actual HT signalling but your aims seems less superfluous than mine. To each, his or her own. I won't "feel free" to post in the iNuke thread but I will "feel free" to no longer own one for more than a few more days. Moreover, I'm more disappointed in the performance than the actual financial loss. My fault really...spurning due diligence, but that won't happen again on the amplifier side. Even so, my suggestion to spur31 was the iNuke 6000 and it was not meant to impugn your project in any way. Apologies if it did.

Finally, 20 Hz content (and below) in HT is much more common than you think. The huge compilation below might change your mind:

http://www.avsforum.com/t/1333462/the-new-master-list-of-bass-in-movies-with-frequency-charts/0_100