el`Ol wrote:

Romy, it would be interesting to test whether it is really that impossible to get into the near field at 30 Hz as Griffin's simple formula in the line array white paper implies. I am thinking about laying the arrays on the ground, having in mind ceiling-mounted arrays in the final version.

An interesting observation about the Velodyne SMS, thanks, Jessie.

There are a number of similar units out there. The Velodyne specification is very fine:   

http://www.outlawaudio.com/products/SMS_manual.pdf

I did not use those units and I do not know how they perform. It is obvious that with drop of frequency the negative impact of DSP will be minimized. How much minimized – that is the question.

There are a number review of the Velodyne and the similar units, I did not read them but I do not think they will be talking about what I would like to know.  Jessie’s transient comparing of the unit in and out bypass I think is not convincing as well.   Still, this area very much worth to explore.  Jessie, or anybody who use the similar units, can you do some specific tests for me? Also, did anybody has a circuit of output stages of those units?

msaudio wrote:

If you put your speakers in the back extra bedroom, you could have your cake and eat it 2. You will have a normal living room and your headphones sound that you love from small room will be back and better then ever and it don't cost anything except your time and bad back, after you move it again. Then all will learn nothing from ordeal, I am reading these comments and i realize why most people's hifi systems sound like shit because they donot have a clue about audio in the first place. Any 1 that would add solidstate in there line of tube electronics is a nonbeliever in audio purity. EQ bab idea, bass modules center of room a joke, that would be against everything this site stands 4.  Preaching Horn Religion     MSAUDIO

30cm Subwoofer

Type Number: 30W/4558-00
• Fiberglass/Paper Sandwich cone, black coated
• Fs 19,5 Hz
• SPL 90,5dB @ 2,83V / 1m
• 56 mm peak excursion – hereof 25mm linear
• Aluminum Short Circuiting Ring and the

Aluminum Spacer on the pole piece to reduce distortion and power compression.

• Aluminium Voice coil former
• Vented cone / dustcap
• Nomex spider
• Low damping rubber surround
• Litze wire woven into the spider

Specs: Electrical Data Power Handling Nominal impedance Zn 100h RMS noice test (IEC) Minimum impedance Zmin Long-term Max Power (IEC18.3) Maximum impedance Zo Max linear SPL (rms) @ power DC resistance Short-term Max Power (IEC18.2) Voice coil inductance mH Voice Coil and Magnet Parametres Voice coil diameter Resonance Frequency fs Voice coil height Mechanical Q factor Qms Voice coil layers Electrical Q factor Qes Height of gap Qts Linear excursion +/- Tm Max mech. Excursion +/- Mechanical resistance Rms Flux density of gap mWb Moving mass Mms Total useful flux mWb Suspension compliance Cms Diameter of magnet Effective cone diameter Height of magnet Effective piston area Sd Weight of magnet Equivalent volume Vas ltrs Unit net weight Sensitivity (2.83V/1m) Ratio fs/Qts IEC Specs refer to IEC 60268,5 third sdition. All Scan Speak products are RoHS compliant

Well Romy:

If you wanted to stick to some known quantities, you might do well to look at these soon to be released drivers from Scan Speak which seem fairly promising, and might work quite well. They are rather inexpensive according to their indicative prices and so may not be such an expensive experiment. The excursion of 58mm is rather good, they are current production and you could easily add more as you feel necessary.

Regards
Rakesh

Thanks, Rakesh. It might be a good driver, I always like Scan Speaks.

A few things. The Scan Speak nowadays is not Scan Speak anymore, just a name and they made by someone else. Also, I would like different type of drivers. I would like 18-24 inches with moderate exertion, low resonance and none-rubber suspension. The suspension on SD-1 motors was rubber but it was different type of rubber and it was feeling like fine leather. For ULF driver the will not be able to use it – too thin. The rubber suspension on woofer is to inertial and suck a lot of overtones. As a result it would request very sharp crossover….

Anyhow, I have no idea what I would need at this point. I need to know what kind midbass I will have and then I will see what would be the best complimentary lower bass. I think another couple day of market crash and I will not be thinking about midbass horn but instead about the second job to afford them…

http://forum.dancehallreggae.com/archive/index.php?t-33718.html

Let's skip the reactions to the context and just deal with the numbers.  Yes, they are trying to play them too loud.  But
-6 dB @ 43 Hz for twin McCauley 6174s should shed some light on the (U)LF subject.  These are not toy drivers, and they are not "vintage" whimps, either.  If nothing else, this goes to show that simply putting a big driver in a big box, or cranking a small "long throw" driver in a small box is not enough for real (U)LF.  The truth is, few do real (U)LF.


Best regards,
Paul S

Possibly reflects poor use of my free time, but:
 
http://cgi.ebay.com/Danley-Sound-Labs-DTS-10-Hometheater-Subwoofer-KIT-NIB-/200476677178?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item2ead57543a

Might never see it at this price again...


Paul S

zako wrote:

Yes i know the expierence,,,I too live in the wild,,As I open the sliding doors,,The Deer across the lake look up as Mahler symphony rolls across the water,, A startled redtailed hawk takes flight,,,  Good to be alive and witness a fresh new morning.

zako wrote:

I wold like to compose a symphony for a Hurricane

I got home today and was listening the music of my carpenter in my basemen cutting the wood for my midbass horn.  I was slowly thinking about the location of my perspective lower bass channels. The Midbass Horns, if the things go well, will cover down to 40Hz and I would like to have another 20-30Hz sealed box channels. Ironically the requirement is the same – I would like them to do the job but do not destroy the room decor – or not to be too mu8ch in sight. Suddenly it hit me what I can hide the LF channels.

Two days back I have a structural consultant inspected my project and he gave me some recommendation what in his view heed to be done. I said him that the weight of each horn inhaled in attic was 1500pounts of 3000 pounds combined. Some of his recommendations I discard but some I find need to be implemented. So, the in the room will be installed an extra vertical poll to support the horns in the middle. It will be 75” behind the listening position, not too disturbing, still leaving a plenty room on the side wide open. I will probably cover this pall with drywall. In the image below it painted with dark blue behind the listening chair.

Then I asked myself – why do not convert the space behind this new wall into a large LF channel with two L and R drivers in opposite side of the walls – shooting in kitchen and in reading room? I measured the space and I got 83 by 25 by 35 inch or around 35 sq foot. This is perfect to make two 12-14 sq foot LF channels with Aura 1808 for instance.

The idea is very elegant and the woofers will be absolutely not intrusive or visible. I need to measure this space and to see if it is a “hot” space in the room. There are some concerns however that I do not like. Firsts is that the distance between the R and L channels will be less than I would like it to be. The second is that LF souses will be BETWEEN the MF islands and this is VERY bad in my books. The woofers will be closer to listening position than anything else, to make delay for LF is not a problem however.  I need to think about it more. The idea is promising but need to be examined more.

The Cat

Romy the Cat wrote:

Ok, I think it is a good time to deal with room acoustics. All infrastructure problems are set. The Midbass horns are underway; the electricity will be investigated but as now is addressed by PP2000. Macondo and Milqs are inhaled, the system is up. It is too easily to think about lower bass channel. I think it is a good time now to think about room acoustics, particularly in conjunction with the room décor. It is very interesting subject; I will share what is going on. As now, in more or less naked room the sound of the room is not good.  Let see what can be done with it.

Black oval is my listening spot.  Red are the midbass speakers 10 feet above me. Grey are Macondo. Blue are the ceiling fans. Yellow are the sails that I am considering to hang 8 feet above the floor. I need to start looking for a right material. It shall be hairy but transparent, wish me lack…

The Cat