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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

    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,
  2. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    It seems Danley is using electrical series on their TH812 subwoofers
  3. 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 !
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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!
  10. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    I did the measurements again to directly compare the 21ID Vs 21IPal Measured at 4 meters, normalised to 2 meters CEA2010 2 m K20 bridge BPH221 ID 4 ohms 20 Hz 104.6 25 Hz 126.2 28 Hz 132.2 30 Hz 133.4 31.5 Hz 133.1 35 Hz 133.1 40 Hz 137.0 50 Hz 141.2 63 Hz 140.1 70 Hz 142.0 80 Hz 143.2 100 Hz 144.5 BPH221 Ipal 2 ohms 2 meters 20 Hz 105.8 25 Hz 126.9 28 Hz 134.5 30 Hz 136.6 31.5 Hz 137 5 35 Hz 135.4 40 Hz 138.6 50 Hz 140.7 63 Hz 142.8 70 Hz 144.0 80 Hz 144.6 100 Hz 145.1 I love these tests. The amp asked for huge amounts of power at 28 Hz where the port is tuned. I've seen 720 V peak to peak and 110 amps on the output with series IPal before the 20A breaker dropped. I can say that the drivers in series are a problem, a big one IMO. Very different excursion at 35 Hz between them, that's why the output is lower there
  11. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    It was the 451. The suspension is more linear and a bit softer. But the glueing seems way better applied and engineered
  12. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    All the measurements were made outdoor ground plane. One space where I measured the TH and F121 , a wall of the building was 14 meters away but the rest of the space is a lake and a field. I truncated the impulse response to eliminate as much of the load as possible. 17 meters the reflection came 100 ms after so I had very good resolution and clean response down to 10 Hz. The space where I measured Stasys XV2 that I will not publish, the BR with RCF , the SKhorn XL and others is a very large space where the building behind and on one side was at 25 meters and the other 2 sides were empty for more than 100 meters. I switched from MC2 to clone and X4 because I own a clone, a K20 and I have 2 X4 for an install that I could use but the MC2 was installed in a fixed place where Funktion and TH are installed. I am using REW for generating and measuring the output, Focusrite soundcard, earthworks M30 calibrated mic , a class 1spl calibrator , a Behringer calibrated mic for comparison purposes. Unfortunately one of the RCF drivers kicked the backplate with the coil former and it isn't in the perfect shape right now. I will soon test the SKhorn XL with 21ID , each driver on a K20 channel to see the numbers. Probably next week.
  13. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    Br221RCF 33hz bridge FP14000 clone 2 meters CEA2010 20 Hz 106 25 Hz 121.3 30 Hz 131.9 31.5 Hz 134.7 33 Hz 136.9 35 Hz 139 40 Hz 141 50 Hz 142.4 63 Hz 140.6 80 Hz 140.8 100 Hz 141.5
  14. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

    CEA 2010 measured at 2 meters F121 MC2 E45 bridge normalised to 2 meters 25 Hz 108 30 Hz 115 31.5 Hz 117.1 35 hz 120.8 40 Hz 127.1 50 Hz 132.3 63 Hz 134.5 80 Hz 136.2 F221 measured at E45 BRIDGE normalised to 2 meters 25 HZ 114.7 dB 30 HZ 121.4 31.5 HZ 123.5 35 HZ 128.9 40 HZ 135.2 50 HZ 139.4 63 HZ 141.5 80 HZ 141.8 100 HZ 142.9 1*TH18 xoc1 measured at 4 METERS MC2 E45 BRIDGE normalised to 2 meters 25 HZ 110.4 30 HZ 123.3 31.5 HZ 125.1 35 HZ 128.2 40 HZ 129.3 50 HZ 133 63 HZ 134.3 80 HZ 134.8 100 HZ 136.6 2*TH18 xoc1 measured at 4 METERS MC2 E45 BRIDGE normalised to 2 meters 25 HZ 116.8 30 HZ 130.3 31.5 HZ 131.9 35 HZ 135 AMP LIM 40 HZ 136.3 clip 50 HZ 139.2 63 HZ 140.2 80 HZ 140.4 100 HZ 142.7
  15. radulescu_paul_mircea

    Ricci's Skhorn Subwoofer & Files

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