kipman725

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)

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.

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.

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?

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

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

possibly they are not needed, its hard to tell because powering the unit up outside its case is tricky.

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

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

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

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.

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.

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.

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

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).

Do you have a MA5002VZ? I have a couple in very bad shape that I'm trying to fix and as they have previously been fiddled with and there are discrepancies between the service manual wiring diagram and the silk screen I'm unsure if the cables P500 and P501are in the correct positions (there are another set of cables underneath them) (this is how it came to me). I did some basic checks against the MA5000VZ schematic on the pin outs and I think this is correct... As for parallel mode like lots of the design of this amp it doesn't make sense to me as at least at the time it was launched the available drivers had 8 ohm voice coils so for it to be useful the amp would have to be loaded with a ludicrous number of drivers. The very large number of parallel transistors approach was used with amps like the Void Infinite 8: https://www.abeltronics.co.uk/amptesting.php?z=Void_Infinite_8_mk2 *on a side note the forum upload limit seems to have been reduced to 0.08MB!?!? (my picture didn't seem to work as well - try https://drive.google.com/file/d/1iQ59CYpxIum91ivtv0ULTfLJV3aFF2jt/view?usp=sharing )

I understand where your coming from, when you hear a well set up PA system at decent volume there is no going back to home Hi-Fi and even if you have the speakers at home the space is too small and the neighbors too close. My situation is actuality pretty similar to you, having spent my whole life not going out much and when I did hearing pretty crap PA systems (line arrays etc) I went to party with a big stack of relfex subs and orbit 4 tops which sounded like an infinitely powerful Hi-Fi and was instantly hooked. Since then I have heard quite a few good systems but never at the larger more commercial gigs. I think I started building up my system a few months after that first time and also started with sealed subs but have recently rebuilt them as reflex due to box heating issues and optimisng for more output in the >30Hz range. For me the reflex is a big improvement but I'm running them pretty hard for 12+hrs. I have only really started building up some contacts in the past year, not been an especially outgoing person. A good way to meet people is to attend local music events and talk to the people running the system (although not possible at this time). A possible issue you might encounter is where I am (North West UK) is a lot of venues have license clauses preventing the use of external sound systems due to historical noise complaints, may not be an issue but its worth looking up your local licensing situation.

I don't have any stuffing in my ported subs as I figured it was pointless with one driver operating magnet out. I only get noise out of them if pushed beyond xmax or if they are pushed at the tune frequency with sine waves (air noise).

https://bonsaihifi.co.uk/ is a similar idea and pretty fun but I don't know how it would be possible to make money from such a thing unless you have a lot of existing contacts (Rich people house parties?) it also won't work if you have to space people out, no one is going to start spending 4x as much in a recession. I can confirm though that people are in general very keen on the oiled wood aesthetic compared to the normal PA black paint so this is a good idea (although less durable). Up to the point you run out of power, money or weight allowance sealed boxes will give the most output per unit volume but in PA use the lack of air exchange can be a problem as the air inside the box gets hot.

these are very solid numbers, if it could avoid blowing up it would probably be OK with 2ohm load. What kind of instrumentation are you using on the supply side?

Pro gear like Behringer DCX2496, Symetrix 8x8 DSP, QSC QSys are often better value for money especially second hand. I run an 8x8 DSP which I have modified for silent operation by replacing the top of the box with mesh and replacing the fan (by using a 12V fan and a 24->12V buck converter).

It sounds like you don't have much space in which case the most compact solution would be equalized sealed boxes. Multiple subs are one of the best sound quality improvements so for home use I would prioritize more smaller subs over a single large sub. Outboard DSP/DSP amps are quite easy to use, you can just enter the coefficients from REW into the parametric EQ. Berhinger Inuke/NX are powerful and cheap but have noisy fans so you would want to locate them in another room. There are also plate amplifiers with DSP available which could be an option if you don't want any large/nosiy equipment.

Flat frequency response is not the most important characteristic considering that room modes have far greater effect. Most people here are running room equalization and house curves so beyond giving an indication of the minimum frequency where sufficient output can be coaxed from the sub the frequency response isn't very important. A flat measured in room response will sound thin and overly bright on electronic music, a typical house curve would be -1dB/octave for general purpose playback but I would add significantly more bass boost for playback at 'party levels' (~95dB A weighted average) of electronic music.

Looking at the VBSS thread it looks like the xmax specified for the PA460 is geometric and so the usable excursion is a bit greater than specified: https://www.avsforum.com/forum/155-diy-speakers-subs/2226642-v-b-s-s-diy-subwoofer-design-thread.html

This may be a concern or not but the SAN214.50 will have more resale value than the many PA460 option and if your needs change IMO is the more flexible option. This is assuming that you only have two locations to place subs, if you have lots of locations for subs making many PA460 subs would be the best option for even bass throughout the room. I would recommend Hornresp for simulating sub performance, its quite easy to use once you are used to the weird interface.