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radulescu_paul_mircea

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Posts posted by radulescu_paul_mircea

  1. Because I have the job to check sound systems in different venues, I often check the subwoofers at high volume to see if there are any problems. Most of the times I use protection, sometimes even earplugs and headphones on top, but there are times when I forget some of my equipment and i have to do it without protection. I can tell you for sure one can have really big problems with his hearing after checking a stack of  4 double 21" subs, flat to 26 hz, for a few minutes. even with my ears covered with my hands, sometimes I feel my ears hurt and hurting is never a good sign. So yes, bass can damage your hearing!

  2. I want first to know what is the audible spectrum of humans, ear and other senses.

    I cannot find any new study where they test the auditory system capacity , to get rid of 20-20k Hz , to make a difference where the cochlea stops functioning and other sesory inputs tend to be more important in the perception of those frequencies.

    I have a professor that states the ear stops functioning at 200 hz hand hands over to other sensory inputs.

    I know he is not right but I have to proove him so if you know of studies please link them here.

    Paul

    Edited:

    This is what I found up to now

    http://oto2.wustl.edu/cochlea/romesalt.pdf

  3. Post anything you find interesting about acoustics, hearing and audio reproductions. 

    It can be any type of study new or old as long as it is veridical and it is not common knowledge. 

    I mean we have to keep things interesting.

     

    • Like 1
  4. So taking that much power even in a very high efficiency system the heat will accumulate very fast. Using the metal wings attached to the motor one can increase the heat transfer but it is not as efficacious as forced air. And using the TruePower counter from Powersoft K10 generating around 1.2-2 Kw per channel drawing on average 3.1 Kw from the wall, to see how quick and how high 4 BC 18PS76 per channel will heat up, in 45 minutes of bass heavy music I ended the test because I got around 35 degrees Celsius increase. So putting only that power in 8 vented drivers I could get that temperature increase. Now imagine 2 KWh in a single 22 kg motor.

  5. I believe the problem is the lack of active cooling . In a normal driver the moving of the coil creates air currents and that exchanges the heat between the driver and the medium but here they use only convection. In the F32 from Funktion one I believe they use the driver as per the image attached with a small chamber of air and in a horn enclosure using 8 of them which behaves more like a full horn.that raises the impedance for a good bit. The thermal inertia is very high so even though it is hard to increase the temperature, it is also as hard to decrease it . The M-Drive can generate around 5000 watt long term and 2000 watts thermal equilibrium so in 2 minutes you increase the temp with 20 degrees Celsius

    post-3306-0-13500200-1477746846_thumb.jpg

  6. I am now playing with these babies and I have a SVS fan client with 3 Ultras installed and we listened to both of them for days now. He will probably end up buying the speakers but also will probably be the first PB16 client.

    As for the dimensions, could the 16" be in fact an 18" but measured only from the suspension edges?

    post-3306-0-85308600-1475779668_thumb.jpg

  7. From the image there it seems its ferrite magnet.

    The spider could be good enough. It doesn't look to be 15" ,more like 12. But when you look at the Ipal driver's spider you can see it is not that huge but it can allow sufficient excursion and control for the application.

  8. The room is 4*4 meters in an apartment building. The level I can get with those subs is formidable, using the amp bridge to drive them both but I took out one of them because it gets scary very quickly and I stay with rent :-D With some processing I got flat from 21 hz, and I try not to exceed sane, normal levels

  9. Keep up with these test! Your test, Ricci's and some others from the DIY community helped me to convince a client to get the best possible.

    I know it is not directly related with Luke's measurements, but I wanted to share a review with you about the Powersoft X4 (and for X8 at the same time, being 2 of htem in a single package)

     http://www.powersoft-audio.com/en/docman/1012-x-seriestestrevieweng/file

    That is a resonably way of review-ing amps IMHO

    • Like 1
  10. In a sealed burst test, I think other important factors besides excursion and thermal compression,are the break-up of the diaphragm, the softness of the adhesives and other small factors that doesn't have an effect at small signals but once you push ove a threshold, those effect starts to accumulate with other nonlinearities.

    • Like 1
  11. Yeah,for that kind of money I would settle with the video.

    They say it uses over 3 Kgs of magnet and that got me thinking that it couldn't all be only in those pillars. The "flower power" arrangement for the magnets looks good but are a little inefficient, from what I know.

  12. The thing in the Ipal system that is most important and interesting is the fact that as far as the designer is concerned, there is an electric input and an acoustic output, size and weight constraints and maximum Spl/cost. Using that DPC allows one to choose a desired transfer function and no matter of the inherent nonliniarities of the drivers, that BI is overwhelming them so it is easy to modify the system to match the target response.

    Even though this 21Ipal driver is formidable on it's own, I really love what it can do in a complete system, in the pro audio domain. Taking into account only the fact that the effects of aging are largely diminished, can expand the life of one's investment and that is a serious advantage.

  13. Martin audio MLX says its 8ohm driver

     

    "DLS18002 18" Driver 8 ohm MLX £1,083.00"

     

    https://martin-audio.com/downloads/datasheets/MLXspec.pdf

     

    8ohm B&C ipal 18"?

    If you look into Ipal AES convention paper, you can see that it "can be matched to any high performance low frequency high excursion transducer, even though it's performance can be maximized if used in conjunction with some specific transducer" and I believe being a matter of cost and profit, it isn't always the best choice to make the best one can do, because for 3 dB extra, it is better for them if you buy an extra box than to spend more to use the best driver. ;)

    I never opened a MLX sub so I cannot know, but they definitely use the Ipal module controlled by their own software

  14. The KV2 specs for the sub's continuous output when two are used is spot on! 141 dB from a pair and 147 from the Ipal version with 34 Hertz extension is the most sincere spec I'be seen for a while :)) that's if you don't read the rest :))

    The Martin ASX user manual is more than interesting. it said about the driver being capable of a 30 mm one way stroke and 152 dB SPL, even saying to limit the peak output if one cannot keep the minimum distance at 4 meters.

    We, DIY-ers have some things to compete with now, not only bass reflex subs ;)

  15. That package is quite good, and possibly even better with the Ipal driver module combo. Also a design a bit larger with a bit lower extension could be a game changer for me.

    Yes , those ports are huge , as are also those in VHD sub, but even with those sizes I measured about 2-3 dB compression at vent running. But for a fact I know that a part of that is because of the power amp because although I had 2 K8, an X8 and a K20 with me that I installed on another location afterwards, I only used the VHD 3200 because of the special connections and I didn't have the time to change them.

  16. The VHD sub is measured as you can see in REW and the simulated response usinng basic band pass crossover looks almost Identical. The sub was measured outside on a beach close rangeand also at 10 meters with no object around closer than 20 meters. the graph is close mic.

    When I was comparing the efficiency and output of the KV2 vs Othorn i was comparing 1 VHD 2.21 IPal vs 2 Othorn Ipal.

    The other sims are fictive, based on what I think the Martin Asx looks like inside, but larger with 2 drivers inside. first would be with Ipal and second with M-force.

    My main question is if the Ipal technology has a way of compensating for the port compression at very high output.

    From what I know, a Helmolz resonator works well when alt the air mass from the port is resonating. when turbulences occur the efficiency drops and after a certain air speed the sistem tends to be nonliniar and the speaker starts to behave almost like in a leaky sealed enclosure with a higher tune and a good cooling system, but that port will not really help the driver to get more sound . That is why I always thought FLH and TH are more suited for extreme SPL than Bass reflex or Band pass. But then I thought that this tech from Powersoft could have some methods trough which they can overcome this problems or compensate for them in a way.

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