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kipman725

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Everything posted by kipman725

  1. I would go for corner placement for the reasons SME states but if you could do 1+2 this would be better. Regarding eq/room correction the best curve tends to be genre/album specific due to the lack of standardization in the frequency response of control rooms so quite often you have a situation where one EQ sounds better with one genre but worse with another.
  2. I have made subs that are long like this and yes you need a lot of stuffing to combat standing waves, the higher you can push the first standing wave up in frequency the more effective the stuffing will be: Another thing to consider is your driver placement is a worst case scenario for standing wave generation (mid pipe). If you consider possible standing waves in the pipe you can have a maximum at the driver and two minima at either end at 86Hz (fundamental modes. You would be better off putting the driver at one end.
  3. I have run between one and 4 subs at home and much prefer 4 subs, they are mostly corner placement. I take a frequency response measurement at each seat of my sofa and vector average the results. After I have dialed in the sub crossover I fit the response to a target curve below 500Hz as my main speakers are close in to the corners and designed to be flat in free space so this has to be compensated for and there are some large peaks in the lower bass that need to be cut to avoid the whole thing been boomy. Works well but I wish there was a more scientific method. SME when you say flattest possible response do you mean an actually flat response? as from my understanding a constant directivity speaker in a domestic room which has a flat free space response should have a tilted downwards response in room (and will sound natural in this condition) so equalizing to flat in room will make a speaker sound overly bright.
  4. Ah ok I thought it might be a double bass setup but was thrown off track a bit. I see a few issues: 1) double bass setup should launch a plane wave which relies on the point sources on the opposed walls been within 1/4 wavelength of each other and there to be point sources within 1/4 WL of the walls. At say a crossover 80Hz this is 1m, however real world this can probably be pushed up a bit: https://www.avsforum.com/threads/double-bass-array-dba-the-modern-bass-concept.837744/ So definitely in your configuration there is no plane wave due to the geometry. 2) Another issue I see is that your room has unequal absorption on each wall due to the french doors. Even considering this I still think it would be better to run two subs rather than one even if running them as double bass array doesn't work due the smoothing effect on room responses: https://data-bass.com/#/articles/5cb5fb285389a80004c7e58a?_k=ymaw45
  5. Placement looks fine, the main thing is to have more subs and place them in a diverse set of locations around the room, they don't care which direction they point. Real rooms differ from the research (in your case you have a large lossy door on one wall) so its not necessarily true the best locations would have been mid wall anyway. Box volume isn't very important (as long as your using EQ) as what produces the sound is the cone moving in and out a larger box is just requiring less power to reach a given SPL when operated below Fc.
  6. 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
  7. 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:
  8. 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.
  9. 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:
  10. 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.
  11. 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)
  12. 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.
  13. 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.
  14. 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?
  15. 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
  16. 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
  17. possibly they are not needed, its hard to tell because powering the unit up outside its case is tricky.
  18. 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
  19. 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
  20. 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
  21. Large caps should have bleed resistors on them, even when stored. In some cases large film caps can charge to lethal voltage sat on a bench due to dielectric absorption effects or polymer relaxation effects. I have been 'thrown' across a room but 3 kM of HV armored cable that self charged itself beyond 1kV and had a large self capacitance. I'm not saying these long term effects are the case here but to me the bus should discharge itself on power off.
  22. Copper sleeves are addressed in the AIC paper as a superior version of the shorting ring as they allow a smaller gap size increasing gap flux (and presumably improving thermals as AE claim). The AIC might just be more expensive to manufacture and hard to market.
  23. 18Sound have some interesting drivers that have little/no inductive impedance rise using a technology they call AIC: http://www.eighteensound.com/media/W1siZiIsIjIwMTgvMDkvMTAvMTFfNDZfMDNfNzU1X0FJQy5wZGYiXV0/AIC.pdf http://www.eighteensound.com/en/products/lf-driver/10-0/8/10NMBA520 I think KV2 might be using their drivers.
  24. It would be easier to design a new amp to be honest using the principles, the patents must be expired by now. Here is an explanation of the grounded bridge: http://aetechron.com/pdf/grbgpapr.pdf Class-H doesn't have to be heavy if a SMPS is used to supply the power rails: https://www.abeltronics.co.uk/amptesting.php?z=crest_audio_PRO-9200
  25. Void used to have their own amp designs up to and including the X series (X6/X8) but now rebrand Powersoft. QSC amps have the capability of combining amp channels in parallel:, series and series parallel: https://www.qsc.com/systems/products/q-sys-ecosystem/products-peripherals-accessories/network-amplifiers/cx-q-series/cx-q-8k4/?L= The MA5002VZ is kind of the ultimate class AB (ish) amplifier (just check its specs, very Hi-Fi). It has a circuit topology called grounded bridge which doubles the effective voltage swing of the power stage and also a circuit that series stacks the power rails. The end result is efficiency like a class-G amp (switched rail) but with the performance of a lower voltage class AB amplifier (no rail switching events, lower voltage faster output transistors). It also includes extensive monitoring that models the thermal reserve of the output transistors and keeps the amp in safe operating area. That means if its working right you can just load it up with parallel sub drivers until the Ilimit lights start to flicker or the amp starts to thermal limit. However to do this lots of the circuits are floating and there is a lot of complexity (no microcontroller) so when the amplifier goes wrong its hard to fix at a component level. Fixing the amp at the module level is very easy though due to extensive diagnostic indicators and easy disassembly. It would have been very interesting is Crown had made a SMPS version of the MA5002VZ as almost all the weight and bulk is due to the transformers, it would have been very competitive with class-D amps (although perhaps not in cost due to the large number of transistors required).
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