Will my sub amp run out of juice? (EQ - SVS) (1 Viewer)

[ColinM]

I am running a 20-39CS off of an NHT SA-2, 165w into 4 Ohms. My response is -3.5db at 20Hz, and +3db at 40. Below 20 it drops like a rock, otherwise it's +/- 1.5db for the rest of the bass spectrum, so there won't be any REALLY big tweaks.

Considering the boost I'll give at 20, does anyone think I'll clip the amp? I am not a ref-level type, maybe once or twice a month I'll demo for a friend, otherwise I keep the volume -20db. I do want it flat to 20Hz, since that's why the sub's there in the first place.

I'll probably use something like the ART-351, since my problems are right at the band freq's, and I find these (and others) all over at good prices.

Let me know if you need more info, and thanks in advance for any replies!

- CM

 

[Ned]

Your 165w amp will have the headroom of an 82w amp if you bump up 20hz by 3db. I add about 3db at 20 and 25hz with my ART351 and my Samson s700 often flashes the 3rd output light (-40db/-20db/Clip). Eq'ing subs up is definitely for those with bigger amps only.

 

[Rick Radford]

>Eq'ing subs up is definitely for those with bigger amps only.<
Er, umm, methinks you mean if you BOOST! But if you do only cuts, no problem!
But perhaps my inexperience is showing. I wonder how many EQ'ers boost and cut.. vs cut only?
I do both, and have yet to see the red clip light on my S700... (remember, I said, "yet.")

 

[ColinM]

FWIW, I'll be cutting that 3db @ 40Hz, so factor that.

I don't have a clip indicator on my amp, wish I did.

Thanks so far, but I'd like to hear some more....

 

[Dustin B]

You don't gain any headroom buy cutting a peak. You do lose headroom by boosting a null however.

The basic rule is every 3dB increase in output requires a doubling of input power. So like Ned said, 165W amp will behave like it has the headroom of an 82watt amp with a sub and room that was actually flat to 20hz.

 

[ColinM]

Still sounds like I'd be fine with the 165w.

Awhile ago Tom/Ron (I won't hold them to this) estimated the sensitivity of the 20-39 to be 98db.

Since I don't push the envelope, even at 85w I'm good up to 118db or so.

More than enough. Good deal. Thanks!

But correct me if I'm wrong.......

 

[Dustin B]

I think a 98dB/W/m sensitivity is a little optimistic and I really don't think a single 20-39CS can hit 118dB at 20hz no matter how much power you apply to it. For my justifcation for this statment see this review of dual SVS CS-Ultras:
Link Removed
Here is a quote about the room conditions the measurements where taken in:

Distance from the corner of the room to the listening position was roughly 12 feet, in a room a little under 3600 ft3

The review lists a peak SPL of 118dB at 30hz with peak 20hz output being 110dB.
Granted that is a fairly large room, but a pair of CS-Ultras is a chunk more sub than a single 20-39CS.

 

[ColinM]

I guess that's kinda my point. I'm not saying I hit 118, by the way. I don't even try. On paper, that's where it comes out. And not limited to 20Hz output, either. I'm not trying to be overly analytical about this.

Like I said, I watch movies at -20dBfs. Do you think I go to 118db? Nope. Wifey'd have my head. Looks like I can EQ in 3db at 20 to flatten it out and not melt the amp.

2500 ft3, 10 feet from the corner-loaded sub in a 'live' room.

Thanks for the answers, guys. This thread can die.

 

[Dustin B]

Ok, I misunderstood you then. That being the case, try it. If things don't start to sound funny during heavy bass sequences in movies, you're a happy camper.

 

[Tom Vodhanel]

Just a quick note:

I was asked about the CS *sensitivity*...I explained I had no idea but you could always back extrapolate from the Nousaine data.

TN hit 114.9dB/31hz/2m/7500 room using the old fidek.

This would be about 124dB/1m/2100 cu-ft room.

TN commented that the FIDEK was never pushed near clipping so he thought our PC(with 180-190w)would perform about the same.

So just saying he used about 240w for this example...

240=124

120=121

60=118

30=115

15=112

7.5=109

3.75=106

2=103

1=100

So in a average room,corner loaded...I figured it around 98-100dB 1w/1m at 31hz I guess.

TV

 

[ColinM]

TYVM, TV