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-   -   Stereo Integrity HT-18-D4... Infinite Baffle...How Much "Safe" Power Per Driver ? (http://www.avsforum.com/forum/155-diy-speakers-subs/1521936-stereo-integrity-ht-18-d4-infinite-baffle-how-much-safe-power-per-driver.html)

TinnEars 03-10-2014 04:39 PM

Per the title...


I have four Stereo Integrity HT 18 D4 for IB install via two manifolds. How much RMS power can each driver "safely" handle (using both voice coils)? Estimates are okay!


OR... What is an acceptable rule-of-thumb regarding "rated specs" (which are probably assuming enclosed) vs. IB? 25 percent, 50 percent, 75 percent? Estimates okay!

Scott Simonian 03-10-2014 04:42 PM

Keep it within RMS ratings (600w) per driver. No need for more.

How large of an area is your HT space?

MemX 03-10-2014 06:16 PM

As per above, keep within rated specs and you should be safe.

WinISD can model excursion for an effectively IB design (just model as a massive sealed box) to give you more confidence.

TinnEars 03-10-2014 06:37 PM

The listening space is 16x24x9. So I can safely power each subwoofer with 600w RMS? I don't have WinISD and honestly am losing my ability to function so I'd rather not try. I'm just trying to enjoy my time for now.smile.gif

Kriszilla 03-10-2014 11:08 PM

Running in IB you may not even need all 600 watts to drive them to xmax. You could always test them free-air so that you can dial in the gain to set your max threshold.


Martycool007 03-11-2014 05:47 AM

So does the SI 18HT D4/D2 make for a decent IB driver? What about the SI 15HT D4/D2 or a set of Dayton HO18's?

gworrel 03-11-2014 07:47 AM

Modeling in Winisd in an infinite baffle, 600 watts total (150 watts per driver) puts them at xmax at 10Hz, never exceeding the xmech. 200 watts per driver is the limit to stay safely within the mechanical limits of the driver without a high pass filter. 600 watts per driver is overkill, pushing them to xmax at 23 Hz and beyond Xmech at about 12 Hz.

Thomas-W 03-11-2014 08:41 AM

Quote:
Originally Posted by gworrel View Post

200 watts per driver is the limit to stay safely within the mechanical limits of the driver without a high pass filter..
Were it only that simple....

The OP is attempting to create a situation where regardless of how the system is driven the drivers can't be damaged.

That's problematic; if he stays to the 200 watts/driver and a signal comes to the amp that causes it to go into hard clipping, (due to insufficient power) that has the potential to do as much damage as does exceeding Xmech with a higher powered amp.

The 'best' solution in this instance is probably to use an amp with a bit more power combined with a high-pass filter. That way there's adequte power for large transients, but the drivers have protection via the high-pass filter.

gworrel 03-11-2014 09:25 AM

Quote:
Originally Posted by Thomas-W View Post

That's problematic; if he stays to the 200 watts/driver and a signal comes to the amp that causes it to go into hard clipping, (due to insufficient power) that has the potential to do as much damage as does exceeding Xmech with a higher powered amp.

Wouldn't it also be possible to set the gain structure so the amp will not go into clipping at maximum volume? Or use an Inuke amp with dsp and set the maximum output there? You're right though, it is not as simple as I stated.

Thomas-W 03-11-2014 09:58 AM

Quote:
Originally Posted by gworrel View Post

Wouldn't it also be possible to set the gain structure so the amp will not go into clipping at maximum volume?

One would need a system that 'clamped' the input voltage to a set max. Easy to talk about probably not as easy to implement
Quote:
Or use an Inuke amp with dsp and set the maximum output there?

Sorry, I'm not familiar with the DSP capabilities of those amps

TinnEars 03-11-2014 12:40 PM

Okay, so 200-300 watts amp power per driver is more than enough and I need to implement some way of avoiding more than 150-200 watts to each. This avoids both amp clipping and reaching driver Xmech. Good to know. Anyone know how to limit amp output... maybe some sort of compressor/limiter? Or maybe low power breakers of fuses at the amp outputs?

moosifee 03-11-2014 01:05 PM

The iNuke DSP models have voltage limiting as a DSP feature.

TinnEars 03-11-2014 01:20 PM

Quote:
Originally Posted by moosifee View Post

The iNuke DSP models have voltage limiting as a DSP feature.

I'd like to try and avoid class D amps. Will a DCX2496 or DEQ2496 perform the same function?

moosifee 03-11-2014 01:43 PM

Why?

No.

TinnEars 03-11-2014 01:58 PM

Quote:
Originally Posted by moosifee View Post

Why?

No.

I'm not convinced that class D has reached true hi-fi capability. For instance, the Behringer iNuke amps I've looked at have damping factors of about 140. Yes, I know folks will argue this isn't important but in my experience high current amps with high damping factors seem to produce more articulate bass... the older big Adcoms to mind.

A9X-308 03-11-2014 02:15 PM

Quote:
Originally Posted by TinnEars View Post

I'm not convinced that class D has reached true hi-fi capability.
For sub amps? Good grief. Driver non linearity will vastly outweigh any distortion that the amp produces, irrespective of class.

As for class D not being high fidelity, you need to look at Hypex for wide band units.

TinnEars 03-11-2014 02:19 PM

Quote:
Originally Posted by A9X-308 View Post

For sub amps? Good grief. Driver non linearity will vastly outweigh any distortion that the amp produces, irrespective of class.

As for class D not being high fidelity, you need to look at Hypex for wide band units.

No, it's not distortion characteristics nor even poorly filtered high frequency switching (not that either are issues with iNuke amps). It's the low damping factor. I realize some class D amps are advertised as having 400+ damping but I've read that this can be misleading in class D amps. I wish I had a way to audition some without wasting a retailer's time but I don't. Is there no other way to set up a limiter other than going with iNuke amps?

A9X-308 03-11-2014 02:27 PM

Quote:
Originally Posted by TinnEars View Post

It's the low damping factor.
Which is irrelevant. What is the DF at the end of 10m of cable, i.e. actually at the drivers where it's relevant? Run the numbers using DF of 140 and 400 and whatever gauge of cable you use and get back to me.

TinnEars 03-11-2014 03:40 PM

Quote:
Originally Posted by A9X-308 View Post

Which is irrelevant. What is the DF at the end of 10m of cable, i.e. actually at the drivers where it's relevant? Run the numbers using DF of 140 and 400 and whatever gauge of cable you use and get back to me.

I don't know how to do that and can no longer learn new things. All I know is what my ears tell me. Like I stated, I wish I could audition some class D amps but I can't. I'm very open minded provided I can be shown (can hear) the facts. Maybe my best bet is to buy an amp, test it, and sell it if I don't like it. But finding amps I like could take months and lots of lost revenue.

Scott Simonian 03-11-2014 03:46 PM

Or you could take our word for it since you are here asking us. Just a thought. wink.gif Obviously you are free to make your own decisions.

There is no reason to believe that the iNuke amps or similar would not provide excellent SQ, especially for this application. Something like the iNuke3000 would be great for this. Just pick the one with DSP built in or not.

I think you're good. smile.gif

TinnEars 03-11-2014 03:53 PM

Hmm... "trust". if you knew me then you'd know how much you're asking. biggrin.gif

Okay, I'll try the iNuke amps. I stated that I have two pairs of SI HT 18 D4 drivers and that's true but I also have a third pair of subs with very similar T-S parameters. I'll need three amps capable of delivering 200-300 watts to each driver into 4 or 16 ohms bridged. I prefer the safer/lighter load but don't want to (can't afford to) waste funds. Which would you do... larger amps bridged at 16 ohms or smaller amps at 4 ohms?

Scott Simonian 03-11-2014 03:56 PM

I hear ya. smile.gif

If you feel like something more 'old-fashioned' would do the trick. wink.gif Then really take a look at the Behringer ep4000. That's your guy. biggrin.gif I figured you had alluded to a more ... "advanced age" to put it delicately, so I thought you might appreciate the lightweight chassis of the inukes. I love the old school amps too but these new inukes are the real deal it seems.

One or the other, really, you'll be more than fine. If you want something good and cheap, get the ep4k but if you want to save some weight too then try out the inuke's.

TinnEars 03-11-2014 03:59 PM

Weight isn't an issue since this is for home audio and home theater... once installed they won't be moved. My concern is best sound quality for the money spent. I do care about efficiency but far less than sound quality.

Two things that bother me: 1. Flabby bass, 2. Gritty mids and highs.

Scott Simonian 03-11-2014 04:07 PM

If it helps, I'm using both amps in both midbass and subwoofer use and I can't tell a difference in SQ at all. I'm still using class A/B for mids/highs though.

TinnEars 03-11-2014 04:17 PM

Which would you folks choose: (1) a single iNuke NU6000DSP bridged into six ohms to feed all six subwoofers, or (2) three iNuke NU3000DSP bridged at 4 ohms into three pairs? For now let's not consider cost.

Scott Simonian 03-11-2014 04:38 PM

Trick question.

The iNuke 6000 can not be bridged. wink.gif

So the obvious choice would be three 3000's. biggrin.gif

Wait. What? You have four d4 18's don't you? That's simple. Just a single 3000 or 6000 would be more than adequate for the job.

gworrel 03-11-2014 04:45 PM

Quote:
Originally Posted by TinnEars View Post

Which would you folks choose: (1) a single iNuke NU6000DSP bridged into six ohms to feed all six subwoofers, or (2) three iNuke NU3000DSP bridged at 4 ohms into three pairs? For now let's not consider cost.

If the sub drivers are not all matching then you don't want to run them off of a single amp channel. Actually, using one NU3000dsp in stereo might be sufficient. Run the 4 SI18s off one channel in 2 ohms, run the second pair off the second channel as a 4 ohm load. Adjust levels and voltage appropriately for each channel.

To answer one of your earlier questions: While the DCX2496 does not have a voltage limiting function, it would allow you to set a high pass filter which would be another way of avoiding ruining your drivers, as Thomas pointed out. I like the iNuke dsp option better.

gworrel 03-11-2014 04:49 PM

Quote:
Originally Posted by Scott Simonian View Post


Wait. What? You have four d4 18's don't you? That's simple. Just a single 3000 or 6000 would be more than adequate for the job.

Scott, you missed: "but I also have a third pair of subs with very similar T-S parameters."

gworrel 03-11-2014 04:56 PM

The NU3000dsp puts out 1000 watts/ per channel into 2 ohms. 600 watts per channel into 4 ohms. So using one channel to power 4 drivers gives you 250 watts/ driver. The other channel into 4 ohms gives you 300 watts per driver. I am not sure how much trouble it would be to balance the output. Someone else might have a better idea. The dsp gives you a lot of flexibility to tailor the output so this should certainly work.

Independent measurements of the NU3000dsp here: http://www.diyaudio.com/forums/class-d/213071-behringer-inuke-nu3000-measurements.html

Scott Simonian 03-11-2014 04:59 PM

Quote:
Originally Posted by gworrel View Post

Scott, you missed: "but I also have a third pair of subs with very similar T-S parameters."

*screeching tires*

Noooooo... I did not.

Hmm.. Similar T/S?

Tinn.... what are these other drivers?

The password to my credit card is Sound Splinter RLp18. biggrin.gif


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