Jump to content

Funk Audio

Members
  • Posts

    62
  • Joined

  • Last visited

  • Days Won

    12

Posts posted by Funk Audio

  1. 1 hour ago, chrapladm said:

    Well thanks for this. BC IPAL's are the best value for myself and where I live. The IPAL pair would be the same price as a delivered 24UHT.  So if the 21" version kept up with the 21IPALS down low then the 24 should be a better option for me if I can swing the payment right now. Above 40-50hz the IPALS run away from the 24" but I'm only after ULF in a sealed alignment.

    Would @Ricci have time to ever test a 24uht?

    I looked at possibly getting one and having one shipped to him. Although I would then have to get a quote for shipping from Ricci to myself in Australia. Either way I'm not in a hurry for a build yet as I have a lot going on. SO I have plenty of time if he is interested.

    Last I talked to Josh, sounded like he would be game for my idea, if only this covid thing would go away already.... maybe one day hopefully.

    I suggested to fly him and his gear up here, we have a suitable area to test, and for the cost of sending him a couple things we could do, well everything we can manage to have prepped 🤪.

    • Like 1
  2. 11 hours ago, SME said:

    Do you know what assumptions are involved?  Particularly concerning the air?  The situation is very different if the air is stagnant than if it is allowed to convect freely.  My guess is that a heat-sink calculator would assume free (natural) convection under some particular mounting configuration (say installed onto an infinite slab).  A sealed box stuffed with insulation may not allow much if any natural convection, so the situation may be worse than this calculation suggests.

    On the up side, if the coil is mounted in very close physical proximity (on the order of one millimeter or less, by my rough calc) to other metal parts of the driver, enough heat could travel them through the air to make a difference.

    The calculator I found allows orientation and ambient temp settings, if I set it to 20c and face down the power drops to 42watts. I am sure one could calculate the thermal resistance of the air in the box and the wood as well and input the degrees/watt resistance to the calculator as well to get a more accurate sim. If I change the ambient temp to 50c degrees, to assume the inside of the enclosure might stabilize at that then the power to get the coil over 220c drops to 35watts. Adding steel helps but even setting the final surface area to what a huge motor would have keeping the source(coil) the same size and setting 1mm air between the coil and steel brings us up to ~55watts at 50c ambient, ~65watts at 20c.  My main point is no matter what you do its usually going to be a dismally low amount of true RMS power a driver can take for an infinite period of time.

  3. 5 hours ago, Ricci said:

    Since we are discussing some type of HIL related rating here...I'd like your opinions. 

    Should I use max burst for it, which will tend to favor passive systems at the higher frequencies due to the absurd amount of amplifier on tap, or use the max long term sweeps which will be more granular and more fair between turn-key systems and the passive stuff, but may under represent the actual dynamic potential by a large amount?

    Alternatively should it be discarded altogether? Too much work, not enough pay off, too confusing for casual enthusiasts?

    I think long term would be best, as most of the time the power level used on a passive system to get the highest sweep is about the amount of power that would be spec'ed for it in use, so even if a system can do more with more power in the upper frequencies most applications wont bother taking advantage of it.

    • Like 1
  4. 26 minutes ago, SME said:

    Thanks for your input re humidity vs speaker parts.  I don't see a rubber surround being too happy at -40 deg.

    Expensive how?  A servo controlled woofer is likely to rely on (re)active DSP.  The Apple HomePod uses a servo woofer in addition to adjusting its room EQ in realtime using data from built-in mics.  I believe many cars already use active noise cancellation.  Some cars also play fake engine noise through their speakers.  I think Harley may do something like this on the outside for its European bikes, in order to provide a "Harley-like sound" while staying within EU noise restrictions.

    I could definitely implement reactive capabilities with my current PC-based DSP system, if there was a good justification for it.  I live in a climate that has fairly large humidity fluctuations.  It's reasonable to assume that indoor relative humidity will correlate with outside dew point temperature, given enough time for the air in the house to equalize.  A/C usage is likely to affect things a bit too.  I now casually monitor dew points published by NWS here.  In the last week, I've seen multiple jumps from 58 deg F (14.5 deg C) to 28 deg F (-2 deg C) and back, each in less than 24 hours.

    Humidity changes have a very measurable effect on absorption in the air of ultra high frequencies.  It's probably reasonable to assume that human listener adapt to these changes when listening to "normal sounds" but audio reproduction systems typically have flaws, and the humidity changes could affect the relative audibility of said flaws, leading to intermittent changes in apparent sound quality.

    I am aware of the things you mention, what I am talking about is going the next level and implementing it in a high end system made up of all kinds of different components, and compensating for driver specific changes, meaning you would need to know what to have the system change to compensate, and where for each part of the system, a little harder to do when its not a complete integrated system. Also I am talking about not just frequency response correction. Again though there is the question of what do you bother compensating for, to what degree and would it be of much detectable value.

    • Like 1
  5. 2 minutes ago, Ricci said:

    +1

    Home audio has it easy with a relatively stable environment. Outdoor pro audio work at festivals and the like is a whole other deal. The worst is car audio. 100+ deg temperature variations, random humidity and barometric pressure, road noise, etc...Forget that tightly dialed in DSP. 

    🤔"reactive dsp" I wonder if that could be a thing, albeit prohibitively complex and expensive I am sure. Have sensors that detect temp humidity pressure and even outside noise, that feedback into a system that compensates in the dsp signal processing with some noise canceling action too.

  6. 7 hours ago, SME said:

    Definitely agree about not really knowing what to test in drivers.  I think it's fascinating that some of the most audible "distortion" is often the hardest to directly measure.  An example of a weird thing I worry a bit about these days is how humidity changes to driver suspension might affect stability of sound quality in a very tight in-room bass calibration.  It may not really matter, or it could have rather profound effects.  I don't really know.  Perception is extremely sensitive to certain aspects of sound and seemingly completely ignorant of others.  Which stuff matters?

    That's what keeps things interesting for me, always trying to learn more, the hows whys and what matters, then how to correlate the science to the perception, by no means does anyone have it "all figured out". Some of science's biggest discoveries have been accidents. I have to humbly admit I have discovered some things by accident myself.

    Humidity can very well affect some materials, thick untreated paper cones would change in mass/damping properties, I have never investigated this so I cant say how significant the differences would be. Most suspensions shouldn't be affected much with the synthetic materials and resins used, temperature certainly can change them though, that is something I consider in designs. For things like that you factor for a range, min max, and make sure everything still falls within desired spec at each end of the range. Luckily we don't need worry about the speakers/subs any of us use(make) working right at -40 or anything like that, I believe that would cause some issues.

  7. 2 minutes ago, Ricci said:

     this type of output density rating is really just for "learning" rather than salesmanship to consumers. They have a ton of other usually more pressing considerations like, cost, looks, warranty service, availability, etc. 

    I do believe your right on that.

  8. 4 hours ago, Wayne said:

    Here is all active commercial subs on data-bass (plus the F113) . Looks to me that linear volume vs log SPL is a decent fit.  The r squared is 0.6684 or a correlation of 82%.  The JTRs also outperform the trend on output at 20 Hz vs size.

     

    image.thumb.png.68dbc302cc2509a53b54d246e02a6176.png

    Have to say I am kicking myself now for not sending in the square versions of the 18.0 and 21.0, those curved sides 🤔

    The 18.0 we make in a 20"x20"x20" cube and the 21.0 in a 22.25"x22.25"x16", both have identical internal volume to the ones tested.

    • Haha 1
  9. 1 hour ago, SME said:

    Well, for subs measured by Data-Bass, there are the max long-term output, power compression, and harmonic distortion plots.  For DIY systems there're also impedance and raw driver response plots which offer at least some hints as to how inductance effects may impact sound quality.

    Of course none of these things can be conveniently distiled down into one SPL "output" number, but so what?  If you want the best, you're not going to find it by looking at a single chart or a single metric.  That kind of "make everything quantifiable" BS is a major error, perhaps even at the root of some of the major problems facing our society right now.  (Serious!)  BTW I say this as an engineer who specialized in study of computational science.

    Also, why CEA at 20 Hz?  Many small rooms have a lot of room gain by then.  My room in particular dramatically boosts sub efficiency there.  The air starts noticeably rippling before the "signal present" lights even come on on the amp.  Tell me what the sub can do at 10 Hz, and then I'm interested.  But of course for someone who need something small to fill a large room, maybe 30 Hz is the money spot.

    Hoffman's Iron Law can be overcome with brute (motor) force.  The limitation then is how much magnetic flux you can ultimately focus on a coil, and whether the end result is remotely affordable.

    FWIW, I spent an excruciatingly long time deciding on which subs to buy for myself.  I had a very specific location and space budget, and wanted the best I could possibly get with that space.  I had to make a custom design.  There was no chart that told me which driver would work best.  I had to consider all the possibilities individually.

    I have to agree with you there, firstly its impractical to test even all the known aspects, things like intermodulation distortion, and subharmonic distortion, are factors I consider in designs that also affect the sound but to test these adds a whole other level of complexity. Besides the fact that who besides the engineers designing drivers/systems know how to interpret them. As it stands a lot of people already don't know how or even misinterpret the measurements Databass does do. I know there are some out there who believe we know all there is to know about drivers and how they work, and how to test every aspect of them and that how they sound can be completely derived from these tests, but I have been listening to designing and building drivers for some time now and even with all the possible aspects we know about and test for I still believe its fully possible that there are things about drivers we haven't even put a name to yet let alone devised a way to test.  

    • Like 1
  10. Hi, Just trying to clear out some space and have a few old random things I would like to get rid of, open to offers on it all. These things have just been sitting around so long I hate to just toss perfectly good stuff but I need them gone so I have lowered prices to bottom line, basically to cover shipping and packing.

    One Aura NS 18 motor for sale. Madisound sells replacement tops for them or someone might be able to build it into custom driver, I do have the top assembly from it with blown coil the cone spider and surround are in perfect shape if someone wants it but that will add some cost to ship. Motor shipped within USA $140

    One Ciare SW18, great shape tested only shipped within USA $175

    Two AE TD12M, they are from different times and so they look a little different but are in perfect working condition. $130 shipped in USA for both

    One B&C 12NDL76 like new. $75 shipped in USA

     

    all sold

  11. On 2/28/2018 at 10:58 AM, radulescu_paul_mircea said:

    If you have the module, can you please tell me how noisy is it? Mine are terrible on this spec, the amp generates a very powerful hiss and buzz through the driver. I've even disconnected the coolers to see if the interference is from there but nothing happened.

    Also, I haven't managed to connect it with power control manager software, I've tried it with two PC's and with 2 different serial adapters.

    I don't know if you saw that they have changed the specs on this one. They reduced the max Voltage from 195 to 180 peak, the current also and the power is now 4500 watts at 2 ohms. In the software the maximum power is 5000 VA PK, current is 100 and true power is 700 watts over a maximum of 3 seconds. This means it is way lower than a channel from a K20 and TBH, if a SpeakerPower SP 6000 is capable to sustain that power for 4 seconds and then to drop to 2400 watts , that is way more that what this one is capable of.

    I found the same issue and that's why we never used it in production as most of our products are used in quiet environments, also connecting to the controls I recall being tricky.

    I am not surprised that they derated it, hopefully that means there are some "hardwired" protections now implemented, because you could set it up in the DSP to be able to blow traces right off the main amp board with over current :wacko:. This I found out the hard way :(.

    • Like 1
  12. I'm, way too busy today to do much listening today, but I've tried a few things.  I did some signal shaping last night that should put me flat to 5 Hz, but I haven't measured yet to verify.

     

    The 16 Hz organ pedal seems to be reproduced with better temporal accuracy and is maybe a bit cleaner without port noise.  I listened to the canon blasts in a 2 channel down-mix of the "1812 Overture".  The single digit content is undoubtedly present, as evidenced by the motion of the woofers, but it's not loud enough to appreciably hear or feel.  Bummer.  I also tried the Space Shuttle recording, and at "-3 dB" from its natural level, I get a decent amount of feeling of lateral motion, but it's not a whole lot more than I noticed with my last subs, which went down to 15 Hz.  So far, I'm thinking that single digit bass may be a dud in here, despite my suspended floor.  It does rattle the glass in the living room window quite a bit though.

     

    Of course, this is all preliminary.  I need to do a lot more tuning and optimization before I render any final judgments.

    Turn it up ????
  13. Are they @ risk of shorting against the CFcones? Resin should provide enough insulation no?

    We did find under extreme conditions the leads would touch the cone, and we had thought the epoxy would insulate it enough *if the leads ever touched but we found it did not. Its not enough conductivity to actually "short" but it did enough conductivity to deteriorate the lead wire. The shrink tube over the leads makes them behave better anyway so it was a win win.

  14. Would be interesting if it could be made to work as such.

     

    I think of the cooling on some of the Sundown and Stereo Integrity drivers with lots of little holes and how those could be coolant pipes or something. I don't know how to get liquid coolant into the motor and around the voicecoil without saturating the open gap with liquid coolant and most likely preventing proper action of the system.

     

    There is no way other people haven't thought about this sort of thing. I guess it would require some serious R&D and engineering just to test it.

     

    Might be easier to water cool an amplifier.

    Air cooling still has a lot of potential before liquid cooling is needed, I have some ideas for some really crazy stuff with unique air cooling system(I do have some ideas for liquid cooling as well), but nothing that's really "practical" either way. That wont stop me though :ph34r:, just might be a while.

  15. Good looking drivers. Should be performers. Underhung drivers with 350 normalized motor force. LOL. :D

     

    Nathan this is a bit off topic but did you start dressing the tinsel leads on the drivers using the CF cones? Just wondering.

    Yes we are now using a high end 3M shrink tube over the whole lead wire, and I am really happy with how they are working, So far in testing they seem to be immune from any possible "flapping"(and subsequent touching of the cone as a result) as can be an issue at certain frequencies when they are long enough to accommodate these excursion levels. And I have never liked leads sewn into the spider.

    • Like 1
  16. I believe he said 4.5 per driver.

     

    Are you talking in sim land?  :rolleyes:. Real world is a little different sometimes.

     

    Based on our in house tests compared to the 21.0, the UH21 given the same power in the same box ~3 cubic feet internal, the long term output sweep was about 1-2db lower across the board, although distortion under 60hz was a little better. Throw it in about 7 cubic feet and long term sweep output was 1-2 db higher than the 21.0 under 50hz, along with much lower distortion. In 4.5 it should be fairly close to that, as 7 is too big, didn't actually take much power in the low end. So overall long term output in 4.5 cubic feet should be similar to the GUJ21v1 as tested 20hz down(but with much lower distortion), about halfway between the GUJ21v1 and the 21.0 20-40hz about the same as the 21.0 50-60hz, and a couple db below the 21.0 above 60hz.

  17. So due to the confusion that seems to be happening with the GUJV1 motor being a Focusworks Audio product, and the GUJV2 being Funk Audio, we have decided we should rename it before putting it up for sale. What does everyone think of; UHFA(driver size) Mk1?, (under hung funk audio, mark one).

  18. If you built the enclosure with panels attached on both sides in front of the drivers spaced away from the cabinet with standoffs, you would have perfectly symmetrical driver loading and you could place it tight to the wall, and also have something close to the other side as well without worry, the "slot loading" affect could be reduced by having both the front and top edges open, vs just the front

×
×
  • Create New...