Moving into basement.. lost LOADS of bass output

[dbworld4k]

Hi guys. Im new to Audioholics.

I recently bought and setup my Infinity Alpha series speakers (A50, A20, C37, and A1200s). The main generator of bass in my system is the pair of Infinity Alpha 50s. Upstairs, poisitoned about 1 foot from the wall, and sitting on carpetting floor (this was the 1st floor, ie. I have another level below) they had a TREMENDOUS amount of bass, enough to satisfy most people without the addition of a subwoofer.

However, once I moved them downstairs into the basement (carpetted floors, finished walls, with oak panels circling the sides of the room) I lost almost all of my bass response. I tried putting them in corners, moving them forward, facing the side walls, and even back walls. The side wall facing position makes a lot more bass than front facing. But the back wall facing makes the most bass (about 80% as much bass as when they were upstairs) at a loss of high frequency clarity.

But the problem is, when firing into the wall, or sideways, I do not feel the low lows much at all (ie. the tones that virbate through your gut and are very low frequency sounds). I also get somewhat of a boomy bass response, although very little boominess is present.

Also, would adding the Infinity Alpha 1200S sub (12" driver, 500 watts RMS. 28Hz - 150Hz) make a HUGE difference?

What is causing the lossof bass here? The fact that the 50s are front firing, or the oak panels. etc. etc.

ANY help is very much appreciated as no man will be happy without his ample supply of bass

Diagram is included

 

[plhart]

From your dimensioned diagram this would appear to be an easy one to figure out. A sealed room's midpoint usually has the biggest null. Since you also have an open doorway at the midpoint the problem is doubly exacerbated. This is why, with your sofa positioned so close to the midpoint that the bass is so weak.

 

[dbworld4k]

Should I put the sub at the small triangular area "labelled zone with high bass output?"

 

[dbworld4k]

.....This is why, with your sofa positioned so close to the midpoint that the bass is so weak.

But even at the stronger bass reproduction areas, the output is nowhere near as great nor acurate as when I had them upstairs which was a 25x30 ft room, completely open.

It just bothers me that my buddy's Interlude 40s outperform the Alpha 50s, and he has it setup in the basement too, on concrete in a totally open room!

 

[plhart]

You could try it. Play with your phase switch as the sub may now be 180 degrees out of phase from your mains. Remember though that you have not changed the position of your couch so it is still very near to the room's null point.

 

[RLA]

Hi
I didn't have to run the mode calculator to see a problem with this room's
listening position and set up. I agree with plhart move the listening position
first and then speakers/sub calculation based on 9' ceiling height


THX RoomModeCalc 1.2






ENTER Speed of Sound MODES
1130.0 --------------Axial-------------- ------------Tangential------------ Oblique
English: 1130 ft/sec -----MOST IMPORTANT-----
Metric: 345 m/s Height Width Length H&W H&L W&L H&W&L
ENTER DATA>>> 9.0 10.0 23.0 13.5 24.7 25.1 26.6
baseline frequency (Hz)> 62.8 56.5 24.6 42.0 22.9 22.5 21.2
EQ 6th octave steps (Hz)
10.0
11.2
12.6
14.1
15.9
17.8
20.0
22.4 22.9 22.5 21.2
25.2 24.6
28.3
31.7
35.6
40.0 42.0
44.9 45.8 45.1 42.4
50.4 49.1
56.6 56.5
63.5 62.8 63.6
71.3 73.7 68.6 67.6
80.0 84.0
89.8 91.5 90.1 84.8
100.8 98.3 106.0
113.1 113.0 114.4 112.6
127.0 125.6 122.8 126.0
142.5
160.0 169.5 168.0
179.6 188.3
201.6 210.0
226.3 226.0
254.0 251.1

 

[plhart]

Another solution would be to leave your couch where it is. It appears that you are only ~8 feet from your screen at the listening position and about 9.5 feet from the front wall. Build a wall behind you which coincides with the back opening of the door or back just a little further. Getting the listening position back about 60-66% from the front wall is usually recommended for a fairly balanced overall sound. The open door can be the monkeywrench in this recommendation though.

 

[dbworld4k]

Ok, I have moved the couch 15 ft into the room, now the bass response is back (still not as huge as when they were upstairs but VERY large improvement nonetheless). Only downside now is that the TV looks tiny lol (even a 60" ). So, anything else we can work on?