2. home-theater
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subwoofer with zero punch... help

I'm a noob go easy but give me the technicals(if any) because I want to learn. I was very excited to get that extra grunt and some good punch from kick drums out of my new subwoofer when it arrived.  I was severely disappointed when I plugged it in.  It only sounds bloated and boomy and there is ZERO amount of punch or slam to speak of.  And I do mean zero! I've had 6in car speakers that "hit" harder than this thing.  It'll shake everything like crazy but there is no definition to any of it. I need help diagnosing where my issue is because I don't think its the sub itself. lol

Sub: SVS SB-4000
Speakers: Klipsch RP-600M (these sounded great on their own)
Amp: ~90s JVC 70w/channel home theater amp 
input: ~$100 headphone DAC and playback from TIDAL
Room: concrete floor basement 26ft x 14ft x 7ft drop ceiling with R19 in the floor joists, full cover thin carpet, lots of furniture and a decent amount of cheap sound absorption foam. 

Other Notes about setup:
1.Sub signal is RCA out of headphone jack, I know its not ideal but splitting rca out of my DAC was worse
2.This is temporary residence, I plan to move but I want to know what my problem is before I bring my issues with me to a new listening space. 
3. The acoustic foam was an attempt to kill the drone from a crypto mining rig which it was successful in accomplishing.

What I tried so far: Tuned the eq for the sub with a tone generator. Found that 65hz was nearly silent, I boosted that and bumped the LPF to 75hz (12db slope). I also tried various boosts and cuts between 65 and 140hz on the whole system but everything sounded worse.  For reference I have 4in woofer monitors at my desk with a little Polk 8 in woofer and it "punches" harder than the SVS 4000.  Like the title says.... Help...
ctstauffer
terry9
2,348 posts
 
For amps, I build my own for the most part. But when I want clean, good sounding, bullet proof power at a reasonable cost, I always use Bryston.

Check out their factory rebuilds by calling them. I emailed them about a month ago on Sunday. The VP responded Monday morning. I phoned him that same morning.Then I bought a factory reconditioned unit that afternoon, with an additional 5 YEAR WARRANTEE. At a reasonable price.
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auxinput
2,920 posts
 
Two things jumped out at me:

First:
Found that 65hz was nearly silent
This is clearly a bass NULL or bass node due to the size of your room.

Second:
The LDF drop ceiling and R19 is creating an enormous bass trap that is sucking the life out of the woofer.
Bass traps do not work like this.  Bass traps DO NOT suck the life out of the woofer.

You can over-deaden a room with too much acoustic treatment, but this is mostly with the midrange and high frequencies.  It's very easy to put too much acoustic absorption into a room and this will definitely suck the life/excitement out of the room.  But once again, this has to do with high frequencies.

If you look at the exact size of the room ( 26X14 with a 7 foot ceiling), Amroc shows a primary bass node right at 65 Hz:

https://amcoustics.com/tools/amroc?l=26&w=14&h=7&ft=true&r60=0.6

I have really bad bass nulls in my own room and the only thing that I found that really affected this was tuned membrane bass traps.  If you want to treat the room that you are in, I would start stacking tuned membrane bass traps in the rear corners.  GIK Acoustics makes their Scopus tuned membrane bass traps.  They have a T70 that you can just buy online at $199, or you can call them and have them custom make a T65 (they will custom make for any frequency).  The cost will not really be any different.
big_greg
6,655 posts
 
Running the sub from your headphone jack?  Uh, no.  If you're using a home theater receiver, it should have a subwoofer out.  Use that.

Which input are you using on the sub?  If you're using the LFE, try the left (line level) input.  

As others have said, the "punch" you're looking for is more in the mid-bass.  A sub is for lower frequencies. 

I have owned a number of SVS subs and currently have a pair of SB-13 Ultras (similar to your SB-4000) in my 4 subwoofer distributed bass array. 

The sub you have is by far the best component in your system.  The sub is not the problem.
auxinput
2,920 posts
 
As others have said, the "punch" you're looking for is more in the mid-bass. A sub is for lower frequencies.
I don't know that I necessarily agree with this.  Yes, there is a definite "punch" in the midbass (somewhere between 100 and 150 Hz).  However, there is an area of bass right around the 60-70 Hz area where it is a very strong and beefy satisfying sound that you can feel.  You could say there is punch missing in this area as well.
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