Ricci

I was going to say...try the SP amp

 

I've driven my IPALs to what looked like near 3" peak to peak excursion with a SP2-12000!!

I'm going to try it out. Probably a single channel on both first to see what happens. Remember I'm testing these in about 2.75ft sealed per driver so it takes a lot more power to get them moving versus the Othorn and the average impedance is way lower. If that works out all right I may try both amps in the 12K connected one to each driver. I'm a little worried on that since it's a 1ohm min load on each and the airspace is shared. If one side of the amp protects or limits slightly before the other that could cause a catastrophic instability for the drivers (suddenly becomes a very high tuned PR enclosure in the middle of a very high power measurement.  )

In other news...I've been out twice this week. I'll be posting the results for the Aura NS18 soon and some other things.

I also tried to run the 21IPAL driver through testing again. This time I crammed 2 in the tiny 5.5ft dual opposed sealed cab I previously used for the 21SW152's, so I could get a 2ohm nominal load for the amp. The K20 still current limited well before getting to the driver limits. Not surprising since the minimum impedance is dropping down near 1.5ohms and the amp is rated for 4ohm bridged. Thankfully those amps are so well protected they won't let you blow them up even when you do something stupid. Next time I'm out and going to let one channel of the SP2-12000 have a go at this cab and see if it does any better.

 

Anybody else noticed B&C's new 21DS115

 

Any place for it in the Othorn Ricci? 3db more sensitive.

 

 

Haven't modeled it yet. I have posted the Othorn HR inputs a few times so you could model it yourself or I'm sure someone else would help out. Looks like a good driver. 3dB more sensitive at what frequency? It has less motor force so it isn't quite as efficient. Should be pretty similar though.

Maybe he has 36 of them and can only run 32...

Thanks for the info. Guess we will see what the waveforms and PvA show. I should get a chance to watch it this weekend.

Let me get this straight, you just bought a Fluke 87V to go with your Fluke 115 and Fluke 117 but haven't ponied up for a DATS system yet? Really?

Bwahaha! Exactly.

What the hell Luke? I think this might explain some things. Spend $150 and get a Smith & Larson WT2 if you want an easy button. I would pay the extra for this over the DATS or WT3. I've had all 3. Or save some money and wire up a voltage divider network like figure 2 in the attached pic and use REW or go ahead and get the ARTA suite for LIMP for next to nothing. Either way you shouldn't be manually plotting impedance 1Hz at a time in 2016.

Hey man what can I say?

I'm glad Brian is expanding his lineup and is able to drop prices a little as well. The amp I have is a loaner, although I do have a need for another ballsy amp for the band space so I'll probably end up buying it. I can see why he is offering the HT oriented models but I'll stick with balanced connections, speakons and a powercon cable.

That's a nice piece of equipment.

Going back to the voltage results a bit. If it were me the first thing I would do is get a baseline for what you are using to record the voltages and remove variables. Forget about high power and voltage and using the speakers hooked up at first. Use a small signal like 3 volts straight out of the amp or a generator and check the readings at various frequencies. Baseline a 55Hz then try 100, 30, 20, 10, 5Hz etc. Any reasonable amplifier or generator should be flat 200 to 20Hz within a very small window. If your meter is measuring variation from 200Hz to 20Hz it is likely not accurate. 

If everything checks out ok there hook the subs and rest of the chain back up and try the same deal once again at a low level consistent voltage. Baseline at 50-60Hz again and change nothing other than the frequency being used. Make sure that you aren't getting weird voltage readings that don't make sense. It should be consistent regardless of frequency until well below 20Hz where you'll start to see a reduction at the lowest frequencies.

Also it looks like your impedance measurements might be done by hand and then plotted or something? Forgive me if that's not the case but I noticed that they look a bit odd too. Especially the Othorn one. It's missing a peak which only shows up as a tiny bump.

Those are some huge cabs for sure. Assuming the guy is about 5'8" the cabs are about 36" high each. Depth is probably 50-60"? Hard to tell with that perspective. BIG. I'll check out the Funktion one site for more details.

unfortunately the graphs seem to have gone AWOL -> http://www.hometheatershack.com/forums/subwoofer-tests-archived/8152-jl-audio-fathom-f113.html

 

not sure why HTS didn't host the graphs themselves, seems a bit of an error

Wow...I figured they would have had that stuff taken care of. Perhaps they do and are unaware that the links are broken. If not that is unfortunate as I don't see Illka fixing all of that a decade later.

AVtalk was the other test of the F113 as I thought. It appears that forum itself is gone. Might be able to look it up through the wayback app.

Actually there is objective data and detailed measurements on the first generation F113. Illka tested it thoroughly over at HTS forum back in probably 2009 or so. It's probably buried in an old archived thread there. I seem to remember someone else also doing a pretty thorough set of measurements on one. There is no reason to doubt that data.

JL has updated to a version 2 of the Fathom line, but a quick glance shows that the driver size is the same and the driver appears unchanged. The amplifier rating has seen a modest bump to 3kW peak up from 2.7kW which is less than 0.5dB of difference. The rest of the change appears to be to the auto-EQ system. There could perhaps be some tweaking to the dsp in the amplifier as well. Performance of the v2 could perhaps be slightly better than the original but it will be a very subtle advantage and not anything huge. I've seen and heard the F113 before. It is a capable subwoofer especially considering its size. That is its main claim to fame is the output it has relative to its size. It also is built very well (USA made), uses quality parts and looks great in person. I'm not a fan of the HPF employed below 18Hz as that sort of defeats one of the main advantages of a sealed system. Otherwise it is a capable performer but very expensive.

Dgage is right...I could possibly approach JL Audio about them sending a unit in to be evaluated but that is not something that I do. I've got more than I can handle already from other parties who are already prepared to send their products. I'd rather work with those who are interested rather than try to persuade a company to be interested if that makes sense? I get an email about once a week from a random person that says something like..."Do you plan to test the SuperWoof 9000? Please test this sub. I really want to see how it does. Thanks." What these types of people should be doing is emailing the manufacturer about it not me.

Typically an amp will have a voltage limit set by the rails and power supply. Say you have amplifier X and it is capable of 50 volts prior to clipping. Since the amplifier operates as a constant voltage device the current demands increase into lower impedances and at some point the amplifier cannot provide enough current to meet the demand to maintain the voltage required at say something like 1ohm. The current is the limitation. If the impedance is higher say 16ohms or something, the current demand is a small fraction of what it was into the lower impedance and the amp is not being asked for much power. In that case you will be limited by the voltage capability of the amp. There is a sweet spot of overlap where most amplifier are able to produce maximum voltage, current and power. It is odd to see a lower voltage limit at a higher impedance. I can't recall seeing that in any amplifier test before. The voltage limit should be constant to my knowledge once it is the limitations instead of the current.

I am not an expert on amplifiers but this is my understanding of modern amplifiers.

Can you do all 4 cabs as wired and a single? It's the voltage being less at 40Hz than 20Hz despite a 20% higher impedance. Just doesn't seem right to me. 

Sorry to keep bugging you Luke but the results still don't look right to me. Do you have impedance curve measurements of the subs in the cabs covering say 2-200Hz?

The 2nd harmonic distortion is lower along with the rest of em so that isn't what I'm hearing with music. It's likely the extra 10dB of top end headroom, less THD, less radical EQ and perhaps less compression all taken together. I've heard Tom D. talk about rapid onset compression of peaks before and never put much stock in it before but I'm starting to wonder after listening to more types of drivers over the years. Like I said maybe it's placebo. That wasn't a smart ass comment. But the measurements do indicate a lot of differences.

Damn Dave. You sure seem up tight. I thought it would be nice to let others see a bit of my thought process behind the driver choice/change and why I was looking for something else anyway. I never said the differences were massive but there are differences. The discussion is about the driver right? Somehow my impressions of using the drivers and the measurements that I have are off topic or something?

Also like to add that you don't need to bump the master volume by much if at all when pulling down the top end of a driver that is far more sensitive up top than the other. That's excess top end headroom not lack of low end when both have similar low end sensitivity. The 19 has better 10-20Hz sensitivity not worse in this case.

The reason I changed drivers comes down to the fact that I was never quite happy with the bass through the crossover with the XXX. HT rumbles and all that were fine. I listen to a lot of music and that was where I wasn't quite happy. Chalk it up to any number of factors. I didn't want to lose any displacement switching drivers though. It took 6 years or so to find a driver that did what I was looking for. I was designing the motor for something that would do what I wanted when this one came along finally. It does sound different to me when the system is pushed especially with music. Call it placebo or whatever but all of the measurements show that the 19 behaves much different and offers measurable improvements in almost every front. Those can be said to be inaudible but they are obvious in the measurements. Displacement per dollar is not the be all end all for me otherwise I'd have bought a bunch of Alpine 15 SWS's and called it good. I don't know what my system choices have to do with anyone else.

What size box is the XXX in?

Same cab for both drivers. Same airspace as the box they were both tested in GP or close enough it don't matter. 4.5ft.

This is awesome stuff!  Every one of your plots show superior in-room results, compared to the XXX woofers.  Congrats!

It's almost like there was some prior planning or thought process behind it??? Nah...Thatd be crazy. What luck!

Scott,

I think I'm done with the HT bass system if that says anything. After I finish the big project Ive got going it'll be time for new mains and CC, surrounds, treatments etc. maybe a riser? I'd rather not but I have been giving it some thought.

Attached here is the response of each after using EQ to achieve a flat response at the main 3 listening positions. The end result of both is quite close. Being within about a 6dB window from 6-100Hz. Note that the XXX system was using a DCX2496 for EQ at the time of this measurement and it contributes to a steeper roll off below 10Hz. It is no longer used since the EQ has been moved into the amplifiers.

Here we can look at the measured electrical signal shaping used to get both to the same final response. It is quite different.

The XXX's required a massive amount of boosting to get the upper bass range back in line with the 20-40Hz range and also some boosting below 20Hz. The 19's also require a large amount of signal shaping but the net effect is much less severe than with the XXX's. The only frequency range where the 19's require extra boost to match the sensitivity of the XXX's is from 20-45Hz. The XXX's require more in the deep bass and a huge amount more above 60Hz. Both have a 120Hz LPF in line.

Now some would think wait...20-45Hz is pretty much the meat of the bass range especially for HT and the 19's are requiring more relative signal in that range. That would be correct but very deceiving. Sensitivity is not efficiency and the 19's due to the huge motor force are much more efficient drivers than the XXX. Let's look at the impedance curve. Look where the impedance peak is and the impedance is highest. Right at 32Hz and from 20-50Hz. This is where the system is at highest efficiency and requires little current or power from the amplifiers. The XXX's also have the impedance peak right near 30Hz since both are in the same enclosure. the result is that yes the 19 is not as voltage sensitive over that range but when actual conversion efficiency is considered it is more efficient overall. The only range that the 19's require more signal boost than the XXX's is right in the range where the system is most efficient and the load on the amplifier is relatively modest to begin with. The sum total is that the 19's are much easier to drive than the XXX's with virtually any content but especially with loud upper bass in the Xo region and with large wide band effects.

This is the in room response of both systems measured at the main head rest with no processing and only the subs playing.

It is easy to see that my room has significant gain below 20Hz (estimated gain profile was shown earlier in this thread)and has a major issue at the seating position at 45Hz and others at about 90Hz and 115Hz. The peaking response of the XXX related to the small air volume and also inductance effects, only makes the peak near 45Hz that much worse due to the positioning of the main seating near mid room. Additionally the sharp nulls above 100Hz react negatively with the very low sensitivity in that region. The rising but smooth response of the 19 matches up better with the particular room acoustics and seating position to result in a much better starting point.  The same room induced issues are still present but are less severe due to the much different response shape. Less overall signal manipulation will be required to achieve a flat response at the seats. Note that the two responses are scaled to the same sensitivity relative to each other as measured outdoors.

There was some question of why I chose this driver to replace the XXX's and how its extremely strong motor and over-damped response with a rising top end translate into a system design versus a more traditional driver. I'll attempt to explain part of my thought process here. Let's start with the sensitivity of the (4ohm) XXX drivers at 2 volts and compare it to the response of the (2ohm) T3 19 drivers at 1.4volts in the same cabinet.

We can see that the 19 has much higher top end sensitivity but the XXX has much greater mid-band sensitivity. The 19 is operating with a low qtc in the sealed test box to the point that it is very over damped. The XXX on the other hand is in a box much smaller than optimum in the same cabinet. This shows up in the low end response of both systems with the 19 exhibiting a much shallower roll off and the XXX having one that is steeper than 12dB octave from 10-20Hz. This ends up giving the 19 an advantage in sensitivity in the deep bass.

Couple of things that were asked for earlier in the thread.

Close mic of the 19 versus a 2m GP measurement. In general close mic exhibits slight top end roll off and slight increase in LF. Hinge point seems to be near 50-70Hz somewhere. Also if more data is needed on this effect in particular I have probably 20 sets of close mic FR directly comparable with outdoor GP. I've already posted a few of the Othorn with different drivers. All of my data on it comes from a few sealed cabs and one tapped horn. Close mics are taken inside my garage. Different baffle sizes may have a large effect.

Might be interesting to try a test at the impedance maximum and see what type of voltage reading you get there.