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kipman725 last won the day on July 8

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About kipman725

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  1. You may want one to remove content in the low region the sub doesn't have useful output in to increase usable output in the region it does. EG. if your sub is -3dB @ 30Hz and you play back the TELAC 1812 recording with 11Hz fundamental cannon fire you would be better off not just going to maximum excursion on the 11Hz and instead reproducing the harmonics*. Only applies if your hitting excursion limits though, if the sub stays in the linear region I don't see an advantage to HPF. *As the harmonics will be distorted by the sub been pushed out of the linear region
  2. I think these area good points I also had some skepticism about the statistical basis for saying that the the small signal values can be used. High crest factor signal is interesting and only reporting 2nd and 3rd harmonic distortion, this suggests some gaming of the results. I think the practical implementation uses voltage and current sensors to inform the model along with reference data obtained from the kipple system of the transducer. There are a few demo videos floating around like this one where parameter variation over time is shown:
  3. I have been reading these papers by Kipple: http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 1.pdf http://www.klippel.de/fileadmin/klippel/Files/Know_How/Literature/Papers/Green Speaker Design Part 2.pdf In the second paper they improve the efficiency of an overhung driver by reducing the coil height to the top plate thickness and then compensate for the resulting non linear behavior. The benefit of this in their example is a 39% in voice coil temperature for a given output compared to an overhung driver (~3dB output gain in the non excursion limited region for the same driver). Considering the IPAL driver already is designed to be a transducer with dedicated amplifier and it has a huge coil overhang it would seem that with just shortening the coil a bit and a new version of the IPAL mod that implements the kipple DSP work they could increase the efficiency/output substantially (IPAL2?). There would also seem to be benefits form changing reducing kms but I understand that this is required to have small clearances in the voice coil gap due to rocking modes.
  4. I have a couple of 15TBX100, yet to go into a box and can confirm its a pretty serious driver. It has many of the features of the more expensive drivers like shorting rings, double silicone spider and a 4" voice coil . What it lacks compared to the top end drivers is excursion capability with an xvar of 11mm VS 19mm xmax for the 18N862 (comparing xmax numbers is difficult between manufacturers as some report geometric xmax and others report 70% Bl and others are just pulling a number out the air almost and other factors such as compliance often limit excursion before BL on high excursion drivers), unless your aiming to get every last dB out of the sub the reduced excursion capability is not going to be important. These videos from B&C show some of the kipple data for the 18TBX100 which show a nice parameters that should result in a low distortion bass like a flat BL curve:
  5. I also wouldn't bother with an additional mid bass cab initially as you will be adding quite a bit of cost and complexity to the system that will run without it, going from 4 amp/dsp channels per side to 5. Saying that I am (slowly slowly) building a midbass horn for the 100-500Hz range which is an unfolded exponential horn so it might be worth looking at what I did: https://www.diyaudio.com/forums/pa-systems/349105-mega-midbass-straight-horn-139db.html This horn was designed for outdoor usage The paper you should read before designing a bass horn is " 11. "Low-Frequency Horn Design Using Thiele/Small Driver Parameters," Presented at the 57th Convention of the Audio Engineering Society, Preprint No. 1250 (K-7), (May 1977). " http://xlrtechs.com/dbkeele.com/papers.htm The changes I would make to my horn in covering say 60 - 120 Hz would be to no longer bother having a smooth straight horn profile and instead folding the horn. I would also reduce the mouth area to less than half the ideal mouth area and use multiple boxes per side. The HD15 has quite a short path length so if you can tolerate a larger box you can get much closer to true horn performance.
  6. If your volume requirements are modest and you want to minimize the size of your sub a sealed box sub woofer would work well, perhaps dual opposed drivers to minimize mechanical vibrations. Such a sub woofer will require equalization to produce low bass and a powerful amplifier to overcome the strong air spring of the undersized box. The driver will be a high excursion type driver. Its hard to make specific recommendations as I don't know your specific requirements in terms of output and size but the Eminence LAB 12 might be a decent starting point. For sealed subwoofers you can use this calculator to work out the maximum output: http://www.baudline.com/erik/bass/xmaxer.html for example 2*LAB12 would be about 115dB@41Hz/1m (lowest note on double bass)
  7. Interesting the difference looks to be the surround; vortex = cloth, Kraken=foam. Foam should perform better (more linear) but early foam surrounds decayed and it should be kept out of the sun. I am a bit surprised they are ferrite as the magnet will be heavy.
  8. kipman725

    AE Techron

    The power outputs are greater than the most powerful audio amplifiers and they claim to be able to sustain such power output continuously rather than been power supply limited to lower than rated power as high power audio amps are: They are also able to be run in series and or parallel for even greater power output. Other interesting features are voltage or current control mode (with smooth transition between modes) and the very high switching frequency compared to audio amps.
  9. kipman725

    AE Techron

    I have on occasion heard rumors of people using these for subs but never confirmed. Specs (and presumably prices) of current models seem impressive: https://aetechron.com/IND-RESEARCH-8500.shtml Also I found this older model which claims to have crown designed amps but offers 5000W @ 0.1% THD into 1 ohm which would be more powerful than the MA5002VZ etc. http://www.aetechron.com/pdf/7700Manual.pdf Any experience with these or other non audio marketed amps?
  10. The K10 seems to require quite strong front to back airflow directed past the components that generate heat. The best solution would be to relocate the amplifier and run cables. Or perhaps removing the stock fans and constructing some kind of manifold that pulls air through the original flow path but using large low RPM fans. However as this this amp has high 2nd hand value you might be best just replacing it with an amp thats intrinsicly quiet. Speaker power has been previously reported to be quiet and offers comparable output power
  11. The 1kv to ground sounds very weird as even if the heatsink was live on purpose you wouldn't expect 1kV to be generated anywhere in the amp. Mix of output transistors is a very bad idea as they won't share current effectively. On the plus side this is making me very certain I don't want one of these amps in my life
  12. possibly they are not needed, its hard to tell because powering the unit up outside its case is tricky.
  13. Art clean box pro will convert the single ended signal from your phone to balanced signal with gain. I did some measurements /modifications on mine to improve LF response: https://www.diyaudio.com/forums/analog-line-level/329210-art-cleanbox-pro-low-freq-modification.html
  14. I investigated dielectric absorption quite a long time ago when I was 17 so my memory is a bit fuzzy. I built a precision high dynamic range current mirror and monitored the charge/leakage current over the period of hours when the capacitor was connected to a voltage source with some series resistance. I also had access to a volt meter with exceptionally high input impedance for monitoring the capacitor voltage. I found that my capacitors fitted a model of a capacitor in parallel with another capacitor with a very high impedance in series with it that represented the long term leakage trend and the dielectric absorption. Static electricity can kill you if you use it to charge a large capacitor
  15. https://en.wikipedia.org/wiki/Dielectric_absorption From my tests the absorption of electrolytics can approach 50% (much more than Wikipedia claims). Solved via bleed resistors. I had a college who liked to leave 5kV film capacitors the size of a thermos flask without bleed resistors attached on his desk and around the lab when I worked at the University. On the subject of amps I see that people who have experience with the Lab clones are reporting better reliability with CVR amplifiers: https://www.cvr-audio.com/product/101.html
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