Funk Audio

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 🤪.

You can see how the early version of this did for seeing what kind of excursion the GUJ platform is capable of here; https://data-bass.com/#/systems/5c2682df1cefb00004803ab5?_k=4sikz2 You can see it can out travel the dual IPAL21 tested, and this version has over twice the normalized motor strength.

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.

That actually becomes a calculable thing at that point. You can call the coil a flat heat sink, there are online calculators to tell you how many watts will reach what temp in ambient air. I put in the area for a 4" coil 2" long, at 50watts it hits 225c so that's where it would melt, high temp coil insulation is rated at 220.

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.

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.

🤔"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.

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.

I do believe your right on that.

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.

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.

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 , just might be a while.

If the 18.0 is run on 240V you gain on average exactly .5db for the burst output, that brings it closer to the peak average. If you look at the "short term averages" chart yes the S1 would still have 0.7db higher burst average 10-125hz, I feel that's "close overall". Yes the S1 has more burst output, and quite a bit at some frequencies, but a little less at others. There are more aspects to consider than just burst output too, for example long term output average 10-125hz for the 18.0 on 120V would be almost identical to the S1, and on 240V about 1db higher. The S1, and S2 as this thread is for are great subs and the tests show it.

Sorry just looking at the wrong graph if your referencing where I said "the S1 and 18.0 look near equal 30hz down for long term output with the 18.0 having a clear advantage over 30hz, as it compares directly to the S2 40hz up" That is burst output your showing, in reference to which I said "Burst output is very close across the board to the S1(take 5db off across the board for the S1 as per your comments on the S2 vs S1), each having a little more than the other in some areas"

Well if you look at the 21.0 tests, and add three db across the board, you get an idea how the 18.2 would look as they share the same motor structure and amplification(per driver) and proportionally more airspace. So it should be nearly matched for long term output under ~30hz, with similar distortion at max output, lower distortion at just below max as already the 21.0 is very close in distortion given the same output level(115db sweep for 21.0 compared to 105db sweep for S2) under 30hz when both are down a couple sweeps below max. Then it walks away for output over 30hz and distortion over 50hz. Not really a fair comparison though considering the cost. The S2, and proportionally the S1 shows awesome performance for the money under 40hz, the 18.2 shows what it takes to match that performance under 40hz at nearly half the size. Massively more power and cost, is what it takes to push the laws of physics hard up to the wall. Comparing to the 18.0 is a little more fair as they are closer in box size and power per driver, although the 18.0 still costs more. Considering the S1 is said to be basically half the S2, so -5-6db across the board. Factoring that in the S1 and 18.0 look near equal 30hz down for long term output with the 18.0 having a clear advantage over 30hz, as it compares directly to the S2 40hz up. Burst output is very close across the board to the S1, each having a little more than the other in some areas, as well as distortion is comparable 30hz down. The advantage the 18.0 has is over 50hz where distortion and power compression are much lower, lower even than the S2 compared directly at similar outputs in that range.

Hi Dave, Don't you think things like impulse response, group delay, power compression, distortion, and inductance related affects change the way things sound even with a matched FR? The RF is significantly better in "all" these "factors" I feel Josh downplayed it but he did say "it does seem like these changes resulted in a much better upper bass range through the crossover region. It definitely seems like there is a better sense of attack and punch on kick drums and sharp upper bass transients when the system is cranked up." I have done enough work with drivers similar to the XXX(and the XXX itself), and with drivers like the RF to concur albeit much more strongly with the differences Josh has noticed, I will agree with the sheer number of drivers and amount of power on hand the differences at normal listening levels would be diminished, but even at that differences are noticeable. On a 1 to 1 basis when driven to limits the difference are Huge, "massive"... and some other descriptive words you may not like...

That's the whole point the "result" is not even close to the same, the same FR is not the end all be all and does not mean they will sound the same, especially when driven hard, there are many factors that will change the resultant "sound". The RF's are a massive step up in every possible way.