From ~100 Hz and up, yes indeed. Much smoother response.
But not much at lower frequencies. Distributing the subs really doesn't help at frequencies below 2-3 times the lowest mode of the room, in my case 46 Hz.
Awful = +/- 10 dB
I have said many times that multiple subs does not do anything below about the second room mode. EQ is the only thing that does anything at these frequencies, but "2-3 times the lowest mode of the room, in my case 46 Hz." or 92 - 138 Hz is way too high. I would say below 60 Hz if your first mode is at 46 Hz.
Or did you mean that 46 Hz is 2-3 times your lowest mode? That would be a first mode below 23 Hz, which is not such a small room.
In my 21 years as an audio professional I've heard this too many times to count. In fact, early in my adventures as an audiophile I had the same opinion. But I've been a speaker and subwoofer designer now for 20 of those years and I have learned and will continue to learn more and more how to manipulate the speaker by tuning the cabinet properly. A properly tuned enclosure is absolutely the key to getting deep, well balanced bass. The amplifier controls the woofer, but the cabinet has everything to do with response. For 10 years I did all my calculations with a pen and a calculator to get a starting point, then I fine tuned by ear and spectrum analyzer. Once I started using software, I didn't trust it, so I still used a pen and calculator. I've been using the same software with updates for nearly a decade now and it's never missed. By repeatedly experimenting with tuning in the simulation software, a designer can create an enclosure with very flat, deep bass that will convince or even trick even the harshest skeptic of vented enclosures. I have far better success and many more happy clients with vented enclosures because they are actually far more flexible than a sealed cavity. Again, the key is to be able to tune the enclosure below any frequencies that will be played at high volume, but that's not usually too difficult. Ultimately, the driver selection truly dictates the type of enclosure. Most JBL subwoofers, for example, do not work well in sealed enclosures. This is not to say I won't use them, some subwoofers do perform better in a sealed box. In the case of the Daytons, they will get much deeper and more linear bass extension in a vented enclosure. I always use what gives the best response for the woofer being used, and the space available for the enclosure.
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I doubt people know what the lowest frequencies are they want to reproduce nor do they know what SPL is required to do so. How the transfer function to the listening position looks like can't be predicted but has to be measured. So how do you design a vented box with all those unknown variables?
It really isn't boxed vs. vented. All I care about is if the result is good. For example I'm using two Ripole subwoofer behind me. But in this particular case closed box designs will be more useful to murillollirum than a rather arbitrary vented design.
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That is based mostly on what type of music they intend to listen to. However, In home applications, It's been my practice to tune the cabinet as low as I can and still have linear response. I always assume the listener will play a system at high volume and will be playing music recorded at the full human audio spectrum. In my experience, that has been very successful for both sound quality and dependability. We all know that playing high volumes below the tuning frequency of the vent will be catastrophic to the survival of the driver. So as a means of preventing that failure, I tune at the lowest possible frequency. Again, this is dependent on space available for the cabinet and the driver Thiel parameters. Like I said, I've been at this for a while and I've learned from my failures and successes.
I use the best design style for the application at hand. Sometimes that is a sealed enclosure, and sometimes it is vented. On rare occasion, I build a bandpass.....
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I just read Dr. Geddes papers on perceived distortion and I think they are brilliant. This does, as in all audio discussions, come down to personal preference. The reason I am currently working on my engineering degree comes from my years in the business and a desire to approach audio systems from a different angle. For me, the math and theory are simply the starting point, final designs must be arrive upon by listening. Not everyone will like what I do, but some will. When clients ask me "Who makes the best...?" I always tell them that is up to their ears. Perception is the only thing that matters to the listener. I can tell you that something sounds great because the measurements say so, but your perception of that product is all that matters to you, especially if you're going to pay for it. I have merely offered help and suggested what has worked over and over again for me as a professional. I try to keep an open mind when it comes to audio. I'm always willing to try something new and experiment with theories. That's kind of the whole point of this forum.
First I wanna express my deep sorrow for the stupid things that happened at Boston. I hope the justice come to those involved in this.
Your information is great! thx for your kindly help. As Mr. Geddes told, reinforced by Markus, the initial approach is with sealed subs, but I will write down your suggestion if I decide to change in the near future.
I wiil do the measurements today, as posted earlier, and we all will get inside the problem, this is the "Small room study case" that is going to take place here in DIYAUDIO.
What a great place here! with all these people so incredible, with experts, gurus, newbies (as I am) excited to get information of audio. Information that is usually distorted by these pseudo-audio-reviewer`$ people.
After all measurements been taken and the advices been tested I will contact Mr. Geddes, as initially I was supposed to, for asking his professional (of course paid) finish adjustments with the DCX as it's very hard to work with EQ without the correct tools.
The information of my room and system is bellow, so it can be a reference to others that want to implement this "Geddes approach" for otimal bass reproduction.
THE ROOM:
3,30M WIDTH (10.8 foot)
4,00M DEPTH (13,12 foot)
2,80 HIGH (9,18 foot)
Acoustic Treatment: Nothing except my bed, sofa, books and chairs.
############################
THE SPEAKERS:
DRIVERS:
JBL 2215H 15INCH WOOFER
Sens. 94.1dB
SCANSPEAK 8545 MIDWOOFER
Sens. 88dB
SCANSPEAK ILLUMINATTOR TWEETER 6600
Sens. 91.4dB
CROSSOVER: BEHRINGER ACTIVE CX3400 24 L-R
CROSSOVER POINTS: 300Hz - 3kHz
Amplifier: DIY 6 mono amps to feed the 6 drivers.
All drivers are matched to 92dB in the crossover level adjustment.
The Midwoofer are working with inverted phase in the behringer, I noticed it's better.
Speaker Size: 170 liters each.
Port tuning: 30Hz.
Position of the speakers:
Toe-in: 25 degrees
Side wall: 30cm (1 foot)
Back wall: 90cm (3 foot)
######################
THE SUBWOOFERS
2 sealed 1 cu.ft. (28,5 liters) w/ DAYTON Audio RSS265HF-4 10" Reference
Dayton Audio RSS265HF-4 10" Reference HF Subwoofer 4 Ohm
1 sealer SVS SB-12NSD
SB12-NSD - SVS
Amp for Dayton: Behringer Inuke 3000
Behringer: iNUKE NU3000
2 x 880W RMS 4 OHMS
Crossover: Behringer DCX2496
Level / Phase / EQ / Delay INDIVIDUAL adjustment for each sub.
#####################
LISTENING POSITION
50cm from the back wall.
the game started...
Your information is great! thx for your kindly help. As Mr. Geddes told, reinforced by Markus, the initial approach is with sealed subs, but I will write down your suggestion if I decide to change in the near future.
I wiil do the measurements today, as posted earlier, and we all will get inside the problem, this is the "Small room study case" that is going to take place here in DIYAUDIO.
What a great place here! with all these people so incredible, with experts, gurus, newbies (as I am) excited to get information of audio. Information that is usually distorted by these pseudo-audio-reviewer`$ people.
After all measurements been taken and the advices been tested I will contact Mr. Geddes, as initially I was supposed to, for asking his professional (of course paid) finish adjustments with the DCX as it's very hard to work with EQ without the correct tools.
The information of my room and system is bellow, so it can be a reference to others that want to implement this "Geddes approach" for otimal bass reproduction.
THE ROOM:
3,30M WIDTH (10.8 foot)
4,00M DEPTH (13,12 foot)
2,80 HIGH (9,18 foot)
Acoustic Treatment: Nothing except my bed, sofa, books and chairs.
############################
THE SPEAKERS:
DRIVERS:
JBL 2215H 15INCH WOOFER
Sens. 94.1dB
SCANSPEAK 8545 MIDWOOFER
Sens. 88dB
SCANSPEAK ILLUMINATTOR TWEETER 6600
Sens. 91.4dB
CROSSOVER: BEHRINGER ACTIVE CX3400 24 L-R
CROSSOVER POINTS: 300Hz - 3kHz
Amplifier: DIY 6 mono amps to feed the 6 drivers.
All drivers are matched to 92dB in the crossover level adjustment.
The Midwoofer are working with inverted phase in the behringer, I noticed it's better.
Speaker Size: 170 liters each.
Port tuning: 30Hz.
Position of the speakers:
Toe-in: 25 degrees
Side wall: 30cm (1 foot)
Back wall: 90cm (3 foot)
######################
THE SUBWOOFERS
2 sealed 1 cu.ft. (28,5 liters) w/ DAYTON Audio RSS265HF-4 10" Reference
Dayton Audio RSS265HF-4 10" Reference HF Subwoofer 4 Ohm
1 sealer SVS SB-12NSD
SB12-NSD - SVS
Amp for Dayton: Behringer Inuke 3000
Behringer: iNUKE NU3000
2 x 880W RMS 4 OHMS
Crossover: Behringer DCX2496
Level / Phase / EQ / Delay INDIVIDUAL adjustment for each sub.
#####################
LISTENING POSITION
50cm from the back wall.
the game started...
Please remember that for me to help the data must be in HolmImpulse format and laid out as I described in the writeup. I don't know if Holm will run on a Mac.
Ok Dr. Geddes, no problem because I can run windows on my mac with Parallels. What are the adjustments for the holm? what should I look for and how to take exactly each measurement?
Thx
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