greg2putt
Well-known member
Very insightful Jonathan. I'll now put in my plans the need to pick up a 2nd Descent I, that hopefully happens in the next year as the new generation subs come out. Yes, pick it up at 1/2 price like the Stage pricing.
As I mentioned in my other thread on the mini media-room system, I'm experimenting with using four subs to smooth out the bass in the room.
Well, even though I've yet to move what gear I do have to the smaller room, I decided to experiment and just place the four subs into the loft system and grab some measurements.
So I carted all four Dynamo's to the loft, good thing they are not too heavy
The loft is a medium-sized room, 20' long by about 14'wide with the 'left' side open to the stairwell, and the right open to an adjoining office.
It is also far from an ideal audio setup, so it presents some challenges.
The receiver I use is the Onkyo NR-818 with Audyssey XT32 room correction (lowest cost receiver I know of with XT32).
Mains are some old Mirage M-290 Bookshelf speakers with matching Mirage center and rear wall mounted surrounds.
Room is untreated stuco, so very reflective at all frequencies.
I brought up my measurement rig to the loft so I could tune the basic setup prior to running the room correction.
So that's the context, here come the tests and measurements.
[Note : it's been more than two years since I started this thread, just updating with latest findings]
So I finally moved the mini-media room to the small room I mentioned earlier. It is the worst possible shape, roughly a cube, 11.5'x11.5'x9', in terms of low-frequency acoustics, a nightmare.
This is why I wanted to see what fur subs could do, and in the loft, it worked well enough, way beyond my expectations. Well now, I just placed the four subs in the corners (offset 4" or so from the boundaries), wired it all up and broke out the measurement rig.
Wow, that's about all I could say for about 5 minutes. Especially once I saw the graphs. Please note: there is no EQ used in the chain during these plots. None.
So here's the baseline frequency response of the left-front speaker plus all four subs operational:
View attachment 18354
Pretty smooth and extended for such small subs, but then, it's a small room.
Now, here's the waterfall plot, again, almost cubic room with no room treatments (well, a rug on the back wall, but that's for HF):
View attachment 18355
Note how fast the decay is in most of the range. Except for the little tail at 50Hz, it's great.
Now the Spectrogram chart, again, showing rapid decay and extremely even response, one of the best I've ever seen:
View attachment 18356
Pretty amazing results for roughly $600 in subs strategically placed in a small room.
JonFo,
My experiences are a match for yours.
I added 2 more Depth i subs for a total of 4 earlier this year. Making adjustments by ear resulted in amazingly improved sound throughout the entire frequency range.
An electrical engineer friend that rebuilt my interfaces on my CLS's had come over to listen to my system after adding my new front end and he pulled out his phone with an analyzer apt on it.
I realize the phones don't have the best mics on them but it showed a flat trace + or - about 7db. This is using only the adjustments on the subs and the treatments that exist in the room.
He said that was as flat a trace he had seen on the many systems he checked.
There is an entire thread on WBT forum by a DR. / Professor about using 1 good sub and 3 much less expensive subs. If I find it again I will post a link.
Some recent activity in the:
Multiple Small Subs - Geddes Approach
thread:
http://www.diyaudio.com/forums/subw...mall-subs-geddes-approach-88.html#post4507217
Congrats, that's an unbelievably smooth response. Not to doubt you, but from 50Hz and below is dead flat. Are you certain that the sound card and mic are properly calibrated? Also, there appears to be a nasty room mode at ~60Hz(if you check dims in a room calc), I'm amazed it doesn't even show up. Can I ask what level you took your measurements at?
Has your Onkyo experienced the speaker/network/USB chip failure yet? Mine is currently in transit for warranty repair of it...it appears they all fail within a couple years, and Onkyo has extended the warranty to cover it... http://www.onkyousa.com/Support/service_info.php
Congrats, that's an unbelievably smooth response. Not to doubt you, but from 50Hz and below is dead flat. Are you certain that the sound card and mic are properly calibrated? Also, there appears to be a nasty room mode at ~60Hz(if you check dims in a room calc), I'm amazed it doesn't even show up. Can I ask what level you took your measurements at?
JonFo,
My experiences are a match for yours.
I added 2 more Depth i subs for a total of 4 earlier this year. Making adjustments by ear resulted in amazingly improved sound throughout the entire frequency range.
An electrical engineer friend that rebuilt my interfaces on my CLS's had come over to listen to my system after adding my new front end and he pulled out his phone with an analyzer apt on it.
I realize the phones don't have the best mics on them but it showed a flat trace + or - about 3-4db. By this I mean less than 10db total movement. This is using only the adjustments on the subs and the treatments that exist in the room.
He said that was as flat a trace he had seen on the many systems he checked.
There is an entire thread on WBT forum by a DR. / Professor about using 1 good sub and 3 much less expensive subs. If I find it again I will post a link.
And now for the post Room Correction (Audyssey XT32 in this case)
Much smother in the 60 to 200Hz range. Energy is better distributed, with a bit more in the under 50Hz range thanks to a bit of boost:
View attachment 18373
And the corresponding waterfall:
View attachment 18374
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