Where's the thump, longish thread

[philmate]

Hi,I used to have a self build sub from iplacoustics.co.uk which i sold to a friend. In his room, 15ft x10ft x 7.6ft(ceiling)the sub really kicked you in the chest unlike in my room.He has wooden floor boards, myself concrete. I bought a PSB 12 ISD hoping for that feeling with the bigger driver etc in my 17ft x11ft x8ft(ceiling) room.I have lower frequencies but still no thump or shock for anyone not hearing D/digital as they should. I have a DC1, Parasound 1205 and a Limit 900se player. The l/r and centre are from iplacoustics and are in my veiw very good, rears are Eltax bipolar.Just purchased a BFD which i have had trouble introducing but getting the hang of.I have a large 50hz to 56hz rise of 10db which i tamed. However with or without this rise i never get that thwack which my friend gets. All channels have been calibrated, speakers and sub tried on different crossovers, 40,80,120HZ re-callibrated via the DC1 and BFD , DC1 sub out to LFE in on the 12 isd. Do i need to move. Anyone near Southend on sea for a demo of theirs ?.
Puzzled
Phil.

 

[Ettepet]

How did you callibrate your sub? Do you have an SPL-meter, on C-weighing?

 

[Ian J]

Anyone near Southend on sea for a demo of theirs ?.

It looks like you may be trying to tackle this the wrong way round. If you have already had one sub that performs well in your friend's room but not in yours and now have a powerful sub that seems to perform well for others but not for you it would seem that the subwoofer itself is not the problem but you either have room acoustics issues that need to be tackled or else there is something wrong with the way that you have it setup.

You need to be asking for someone in the Southend area to come round to yours as going to hear their sub won't help you in your situation.

 

[Nimby]

Phil

We really need a bit more info if this is going to be a longish thread. Sorry I couldn't resist it.

Is your room closed or has it large openings to other rooms?

Is it a normal rectangle?

Where exactly in the room do you have your sub?

Are you sure your sub is in phase with your speakers?

A quick check of expected modes using your room dimensions with "Room Mode Calculator" doesn't show any obvious problems at the 56Hz you mentioned. Which is odd.

Nimby

 

[Diamond]

Are you sure you didn't hear just harmonic distortion when it thumped? If there was a peak @50Hz, or the sub was too loud? There are different types of friends..

I mean this box of yours puts out clean bass, which takes time to get used to. "If you can hear the sub, it's too loud", a wise man once said.

 

[philmate]

Hello again...my room size is as above though plasterboard ceiling is 8ft. Front three in corner to the right , sub on same wall 3/4ft from the other end angled, port towards fireplace to its right . I sit oppsite slightly to the sub side on the sofa, doorway to my left, other sofa along shorter wall to my left. Set up as per snapbug, Lexicon and svs manuals.Config at the mo, Sub 120hz all others to 80hz.Tried 80hz all round aswell. Intial figures like this, 17hz 74, 20hz 81, 22hz 83, 25hz 84, 28hz 84.5, 32hz 85, 36hz 83, 40hz 81, 45hz 88, 50hz93, 56hz 82, 63hz 88, 71hz 81.5, 89hz 75, trailing down to the 60db's. BFD set up (i think these numbers correspond) 50hz+1 1 -29, 40+10 1 -6, 63+0 1 -7, 45hz down to 80db, 50hz to 78db and 63hz to 81db. Mark Grant cable was swopped for much longer cheaper cable to help locate sub. The bass limiter in the Lex is set to off, not sure what this does except increase bass volume, uh is this where i may have gone wrong.
Phil.

 

[Diamond]

Please use Room Arranger to sketch your room, it's free to use. Then we'll be more able to assist.

 

[Ettepet]

Philmate, the settings you mentioned for the BFD make no sense to me. Did you use C-weighing?

My own current BFD-settings I derived from using the DEQ2496 + Behringer mic as an SPL-meter and a test-disc ("Acoustic Elegance" - Test CD Volume 1) with many "Warbles" on it. Warbles are short-interval frequency sweeps, with which you can average the SPL of a whole interval for quick and easy measurement.

 

[philmate]

The sub was measured slow c-weighting. I have tried at both 70 and 75db. Iwill try to upload a couple of graphs, these were early ones and the figures may not be 100%. The second test was with the port bunged as in an earlier thread, very similar.Tried to upload room arranger, said not thr right kind of file. However with the figures i have i would expect the sub to kick me.If the bass limiter is set to off and i calibrate the sub would it have similar output if this was on, (-5 to 35db) and calibrated. I assume if off all LFE is let through.
Phil.

 

[philmate]

Heres another, i think this one was port bunged not the last one with filters set as stated before. Filter one 50hz+1 bandwidth 1 -29db, 40hz+10 bandwidth 1 -6db and 63hz+0 bandwidth 1 -7db.

 

[Ettepet]

1. This last graph you gave would make me look for a better location. Big wide -17dB intervals is not what you'd want.

2. With the graph looking as it does you would HAVE to hear/feel big Thumps with heavy LFE material. Try running Jurassic Park III's "Jurassic Lunch" (link), which should have your sub running out of breath easily. Or better still, the DTS R1-version of 'The Haunting', where if there's something wrong with the LFE-channel you might not hear any Thumps whatsoever.

 

[philmate]

Link... way over my head...last graph was just to see how the ported version with the BFD compared to the port open, the same filters were in place.With the other graphs should i get a kick, I would think so. To me the db's are there but the impact is not.Does the kick in the chest only come from low frequencies ? i would have thought they come in higher so people with subs not in the right location can enjoy some of them as users of subs can not always have them in the ideal postion due to WAF etc. Shall i post a graph with no filters and with filters introduced, done the way i think it should, may take a few days though.I just don't get that kick in the chest. I had a Yam e800 processor before so i don't think it's the sub output of the Lex.
Thanks for your interest,
Phil.

 

[Ettepet]

The real 'kick' comes from tones below 40Hz in my experience. I also discovered that people in a mainly wooden house have much more benefit from impact than those (like me) living in a well-build concrete building. When the ground (almost) does not shake the experience is lessened substantially. Hence I am looking to buy some butt-kicker(s) to help me out, and reduce sound levels somewhat for my neighbours.