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radulescu_paul_mircea

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About radulescu_paul_mircea

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  1. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Today was the delivery term, but because of the holidays, it will be a small delay. I'll post some pics and my opinion when I get them.
  2. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Going back to my issue with the drivers in electrical series, I can say there is absolutely no difference between them linked like that or parallel. All my tests and measurements showed me nothing changes, a small voltage difference is present, but only 1-2 V at 60 V sines.
  3. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    A K10 is more powerful and efficient than an FFA10k. On a pair of SKhorns 16A will be enough on the long. But you will see a voltage drop for sure and also you will see lots of amps drawn on the short term. On the K10 and K20 I have I've seen 47 amps at 225 V on display for large peaks. That's on the power supply, not the output stage. There I've seen 100 Amps and 220 V peaks on the K20 meaning 11KVA reactive power.
  4. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I would recommend 2 drivers in series with a K20, one sub per channel. Or a SP12000. Or a driver per channel on SP12000 if you want to melt the coil in the first song. It works well with any amp capable of driving 2 ohm subs. The average and minimum load are higher than what one would get if one would use a pair of 4 ohm cabs per channel like a Stasys X, DBH218, F221 etc that would drop lower on minimums.
  5. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Why did this disappear?
  6. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I just bought a pair of B&C 21SW152-8, a pair of RCF 21N551 and a pair of 18Sound 21NTLW5000-4 and I'll load all of them in my XL version to see how close the sims get to the real deal and why.
  7. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Nice!! SW152 is the best choice except IPal. I worked with PD2151 in some different alignments. Huge efficiency, even higher that the IPal drivers. Low MMS and very high BL. They can take a lot of voltage I low order alignments , they are very well suited to 4th order bandpass. They are conservatively rated at 1000 ( in comparison to other well respected brands) but they can really take 400 watts thermal dissipation, but they cannot dissipate that much heat as one IPal driver and the excursion is limited. Very linear, better than most in craftsmanship,
  8. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    It seems Danley is using electrical series on their TH812 subwoofers
  9. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I wanted to post this picture from last night. They are way more powerful under 45 Hz than 6 Electrovoice Xsub. I used them all in a configuration where I had a null in the DJs spot and a good spread across the venue. With any song that had serious content under 45 Hz, if I turned mine off, the 6 dual 18 were at least 10 dB lower than the whole setup. I love their sound !
  10. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I don't have 2 ohms 21Ipal drivers. They do not exist for now. The power of the IPal module is exactly what a 21Ipal driver is able to handle in a well ventilated enclosure. I'm not that impressed either. But I don't have access to SpeakerPower amplifiers in Europe, especially with the taxes we have around here . It wouldn't really be a good competition for the price I can get the modules or other amps.
  11. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    No, they are single voice coil drivers. But there are 2 drivers in the same enclosure. The difference in resistance gives a small variation. That variation will change the electromagnetic parameters a bit. The variance in the magnetic field intensity adds to that. Then the mechanical parameters of the soft parts will change the general impedance curves between different drivers in identical enclosures. If this drivers are linked in series, being reactive loads, they go haywire even with small variations, because they ask for different voltages and amperages but also with different electric phase angles and this way the variance increases. Then at the onset of large nonlinearities in KMS and BL , the difference can increase quite a bit or decrease if you are lucky. But the difference in load is a difference in temperature, a positive feedback occurs in a worst case scenario. I work with my subs in a pro audio environment and they get used to the limits often. I need to get rid of this problem and the only way is by using them in parallel, with one amp per driver. This sub loaded with 2 21Pal presents a 2.25 ohms minimum load, 3.7 average in series so I would need an amp that can be stable at 1.1 ohms minimum at very low frequency and high power, meaning I'm left with 2 IPal modules per unit. From an economic point of view, it is not very good, I would be better with 2 separate single driver enclosures, where I would gain efficiency, output and portability at the same time. But a dual 21 dual IPal module ultrasubwoofer sounds very fun for fixed installations.
  12. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Off course I did flip the Voltage meters to take them out of question, I changed the polarity, I changed the frequency, I put them in parallel on the same channel or different channels. The voltage difference exhibits only when linked in series. It is way way worse when they are free air, when they are not loaded by the enclosure like under port tunnig. The excursion difference is pretty obvious when I have the hatches open. I never tested their TS parameters. 2 of the drivers are not with me for now , they went to warranty, one of the remaining will go soon. The same thing happens with the ID drivers, the voltage is extremely different when measured but in this enclosure one driver had 1 hour of break in before loading, the other didn't. After 10 hours of high level music, the difference diminished but it was present still, at about the same level as with the IPal drivers.
  13. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I am referring to electrical series not acoustical. I confirmed my theory by Akabak first and then I measured the voltage at the drivers connectors and they differ by up to 6 V when driven with 80 V. So one driver gets 37 V and another 43 V at the same time measured at 38 Hz where driver excursion is maximum. I'm going to test them as you said Sunday. Outdoors with drivers in series and parallel impedance and magnitude.
  14. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    If you look at the measurement I posted since I built these 2, youll see they all are a bit different, especially between 32 and 45 hz. The first ones are with the drivers in parallel, the last ones are with drivers in series. A different Q behavior... Look also at the response of one enclosure vs 2 of them, the ports get better with 2, a higher Q and at least 1 hz lower extension. Off course some of them differ because the space where I measured them is different and no matter what post analisys I use, some reflections will get into the final impulse response, otherwhize I loose resolution and accuracy down low. these differences account for about +- 0.5 to 1 dB sometimes.
  15. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I put my camera inside many times. it does appear to have a problem there. Also the behavior is different when drivers are in parallel, the response between 32-39 hz is 1 db higher in sensitivity, but this I still need to verify again. when the hatches are open and i pass a sine wave anywhere under 50 hz, the drivers excursion is visible and the difference can be very big, like double somewhere under Fs. I'll instal the Ipal modules on them loaded with ID and I have decided shorten the ports to go to 32 Hz instead of 28 Hz as it is now. I wanted them to be 30 hz, I thought they ended up at 29 but 28 is definitely too low, especially for the 18Sound ones. I need to cut 16 cm out of them to be able to get close to where I want them to be but I have a vertical brace in my way. from the experience with the BR with RCF and from sims, going to 32 Hz will increase the output by about 3 db under 45 hz, the output at 30 will be the same and under that it doesn't matter anymore, because the place where they will be installed doesn't need anything that low. Again, I'll have to say about the sound of it, it is absolutely fenomental. The impact that 2 of these have is awesome. I'm in the process of designing and building another set of 2 slightly modified but the same dimensions. I can't wait to hear them together. I took a measuerement between front and back. Unknown voltage, 2 subs one on top of the other, equitemporal distance, so the distance are matche in impulse delay, not in ruler. very good directivity!
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