Bossobass Mini GTG Thread

[coolrda]

Sent you a pm shred.

[Shredhead]

http://mbf.me/wU76eH

 

Here's a link to download the Dark Horse Damage song.  It's dynamic, not compressed so it's not very loud overall.  It's mixed in 2 channel 24bit/96k.  Shoot for listening at +8dB hot on SW from flat and then adjust from there based on your taste. 

 

Intro:

 

Hook:

[Bossobass Dave]

Hope everyone here has gotten fireworks, sunburn and hangovers out of his system.

 

Poor Nick has made the big mistake of posting in the AVS DIY forum (are they really using the 'S' is for 'science' bullshit over there?). And Stereodude is the guy who tells you what to build as long as he can call in DIYSG for backup??? Sorry, 'dude, but you said you come here to read only and that saves me having to re-open my account at AVS to call your dopey remarks about subwoofers.

 

Anyway, Nick posted that it takes 4-LMS-Ultra-18" drivers to equal 1-HS-24" driver. That's a simple statement that even the noobiest noob should understand with little difficulty.

 

That remark was immediately followed by some fella stating that DB measurements say that 1-HS-24" can't even compete with a pair of LMS-Ultra-18" drivers 'in every desirable performance metric' or some such.

 

Nick then said that a pair of LMS-Ultra-18s were handily trounced at Brandon's GTG. Brandon chimed in and agreed with the statement and mentioned that SpecLab showed virtually no THD in playback of typical ULF soundtrack scenes while handily trouncing the pair of LMS-Ultra-18" drivers.

 

Then the AVS piling on mob mentality reached it's fever pitch. First, notnyt chimes in with his ported sub-worship baloney, irrelevant as it is to the OP and subject being discussed. I guess he still wants everyone to refer to his measurements for that comparison, I dunno. They can be found in this forum with a cursory search if anyone's interested.

 

Port the LMS-Ultras, the GTG was subjective, the LMS-Ultras weren't co-located, who uses SL to measure THD... lol, Nick continues to act as though he actually designs and builds drivers instead of just modeling them in WinISD.

 

Fuck me.

 

I just glanced at the DB measurements that were referred to. Here's a direct comparison of the CEA-2010 Max burst results with single driver HS-24 vs single driver LMS-U vs 4 drivers LMS-U:

 

So, is this^^^ "performance metric" not a desirable one? How about average, 10-125 Hz? SI = 121dB, LMS = 114dB. How about long term average, 10-100 Hz? SI = 117dB, LMS = 112dB. Looks like 4 to 1 to me.

 

What I suspect is that the libelous slanderers are assuming double power and double drivers as their ammunition to beat Nick over the head and accuse him of lying, misstating or whatever it is that has them bleating like sheep.

 

So, if they assume that it's a good comparison to include a K-10 on a dedicated 220V-50A line for each LMS-Ultra-18" driver, they should probably say so.

 

WinISD is a great way to model native frequency response magnitude with 20V or so sine sweep input, but that's where the predictions end. This isn't an arguable subject. Of course, that won't stop guys like Stereodude from arguing the point ad infinitum. Good stuff.

 

notnyt is the funniest guy in the mix with his whole 'just port them and you'll see 15dB increase..." nonsense. Sorry, Rob, but you deserve that one. Out of context, off topic, thread derail and we're still waiting for the 145dB at 10 Hz measurements to compare with your previously posted 130dB at 10 Hz LMS-U sealed system results.

 

And, who uses SL to "measure" THD? LOL? Brandon didn't say we "measured" THD at the GTG. He said the HS 24 played back clips with no THD while mopping the floor with the pair of LMS-u drivers. Of course, you fellas have no doubt devised a better way to see harmonics during playback of a soundtrack clip... you know, the actual source played through the actual subwoofer? Prob have measurements to show using that flat-to-DC rig we keep hearing about as well... LOL.

 

The HS24 is indeed 4 of the LMS-U. A single one of them did indeed trounce the pair of LMS-U with it's thumb up it's ass. Co-locating the LMS-U would not have mattered. I also like how the poster somehow knows what the respective responses were at the seats in the comparison we did. Take all of the attendant's words for it or invest some cash and try the test for yourself.

 

Nick, just pop in there once in a while and agree with whoever is the current Marty of the week and you'll do just fine. Otherwise, watch out for that inductance shit... it's bad stuff.

 

 

 

 

[tuxedocivic]

Dave. I called out Nick. He made statements in PI's thread that were clearly incorrect (doesn't understand percent vs fractions and went from saying throw any eq at it then changed it to '3db eq changes are normal'). All while being condescending to a poster. He's in a unique position where if he wants his business to do well he needs to be careful what comes out of his mouth.

 

I then called him out again when he started a thread touting the HS15 using info from this very thread where AVS was bashed. He wants to bash AVS yet use it as a platform to sell his product? Sure, go ahead, but I saw it fitting to let people know how he feels about the place. Again, he should watch what comes out of his mouth (keyboard) if he wants to do well.

 

I could care less what people think of SI or AVS. But I sure am annoyed by false information and rude posts to someone trying to help (see PI's thread).

 

BTW, I don't have all the back story, nor do I care to get it, but I think you don't have it all either. I believe people were saying two LMS18 had the same displacement (so ya, requires double the power to realize it) as a single HS24. I don't recall anyone saying hooking up two instead of one would equal an HS24. The bit I did see had Nick side stepping facts. Sure, seems like the haters were really picking out semantics and details, but it's not the gross misrepresentation of data you make it out to be. In fact, they seemed to have had the data correct (again, just picked to death).

[Bossobass Dave]

Hey Tux,

 

I'm only commenting on the threads that are pertinent to me.   I don't care what else goes on at other forums.

 

One thread concerns a build that I've been asked my opinion about in PM on this forum and the other is Nick's thread over there with content taken from this thread.

 

The posts say that one HS24 can't keep up with two LMS-U according (supposedly) to the measurements here at DB. Sorry, but that's not true.

 

The second thought is that somehow David's pair of LMS-U were not set up properly and there was some significantly disparate frequency response at all of the seats at Brandon's GTG. Sorry, but that's just bullshit from the peanut gallery.

 

The rest is just condescending nonsense from the ivory towers of Desterdome and notnyt, neither of whom has ever posted anything significant from their respective positions that I'm aware of.

 

The bottom line for me is that this is the same old crapola that chased myself and many other posters from AVS forever. There isn't a single solitary soul in that mob who knows anything about the HS24 in a subwoofer system, yet they bait Nick into these silly debates about inductance and Klippel as though they have thoroughly explored the depths of possibility and performance with actual (and not self-dictated) content.

 

Nick's posting style is irrelevant. If he's posting bullshit specs, I agree he hadn't ought to do that. But, what I'm responding to is not that at all. Nick said one HS 24 equals 4 LMS-Us. He's right, according to Josh's outdoor regimen. Maybe a gnat's eyelash less than four (depending on the metric you devise from the available data) but certainly more than 3 and most certainly not less than 2.

[tuxedocivic]

Sounds like we're talking about different threads then, my mistake The timing was uncanny.

[Ricci]

The HS-24 driver does not have the displacement of 4 LMS nor does it have the thermal handling or the upper end sensitivity. It is pretty close to the maximum displacement of 3 LMS which is a crap load of displacement no matter how you look at it. All of the numbers bear this out. It's a beast at moving air no doubt about it.

 

As most of us agree, looking at the burst tests above the displacement limited region are not indicative of real world situations since no one puts that much amp on a single driver. That being the case we can disregard the 50Hz and up burst data since we are talking about displacement. 10-31.5Hz bands are the primary focus for determining displacement. Neither of those drivers were using the whole amp in those bands so assuming that 4 LMS would receive the same amount of power as a single 24 and therefore only get 6dB instead of the full 12dB gain is a bunk comparison. We can make that comparison the way Dave has done with the power to the 4 drivers being held to the same amount, but if it is going to be done then it must be pointed out that each LMS would receive 1/4 the power and be required to do 50% of the excursion of the 24" in order to match it's SPL and would not be anywhere near their limits if employed that way. The 24 could be pushed to it's excursion limits with the same amount of power on the other hand. Also all 4 LMS's would be using the same amount of space as the single 24". It cannot be forgotten that the 24 cab is huge at about 16 cubes and that gives tangible benefits below 40Hz compared with an 18" stuffed into 4 cubes.

 

Another thing is that the amp used for the 24 was the K20, not the K10's which I've sold. On paper that is roughly 1.5-2dB more amplifier burst capability which will boost those upper end burst numbers for the 24 a bit over what they would have been with the slightly weaker K10.

 

Compare the voltages used to achieve the displacement limited burst output below 40hz of the 2 systems. Compare the sensitivity and maximum long term output data and the compression data.

 

I like the 24 I think it over achieved somewhat and it bettered what I had thought it would do in the measurements. I'm a fan. If I did an IB I'd go straight for them. It competes with or out displaces multiple good 18" drivers but it isn't magic where it is curb stomping 4 of the best measuring 18" drivers ever.

[Bossobass Dave]

It has become evident that forums have spawned a powerful urban myth that driver, box and amplifier equals performance.

 

The box may be a simple sealed cube, a larger cube with a pipe installed in a hole cut into one of the cube's sides or a gargantuan labyrinth whose mouth is exponentially larger than it's throat and into which you can easily fit a side by side refrigerator.

 

The amplifier may be a so-called bang-for-buck pro sound rack mount or a plate amplifier that enjoys the attention of ID subwoofer manufacturers as long as the dollar-per-watt number is the lowest available, even if that number is not properly defined and the amplifier wins the people's choice award for that week, month or year.

 

The driver may be one that enjoys the Ricci bounce. That is, it may be a driver that Josh pops into a sealed box and applies the outdoor ground plane regimen of tests signals to through a K-20 amplifier that's plugged into 220V-50A mains, capable of feeding 11,000 watts of sustained power to the driver. The fact that no one on any of the forums has the capability to match with the likes of a Behringer iNuke amplifier (for example) that's plugged into a 120V-15A duplex outlet in his home seems irrelevant.

 

The additional fact that all of the soundtracks we post about in these forums will feed high levels of content consisting of a few octaves below Josh's minimum of 10 Hz seems irrelevant for the most part to the discussions. Since there are only two subwoofers Josh has ever tested with the manufacturer's amplification as well as with the K10 amplifier, I can only cite those to make this point. Take the Craig Chase VS18 subwoofer vs the JTR Captivator 1400...

 

The Cap 1400 short term average from 20-125 Hz is 5.5dB higher than the Chase VS18 in the same metric when the VS18 is tested with it's manufacturer's supplied amplification. But, when the VS18 is tested using Josh's amplification, the VS18 bests the Cap1400 by a fraction of a decibel. IOW, you go from needing 2 VS18 cabinets, drivers and amplifiers to match the single Cap1400 to a single VS18 besting the Cap1400 with a single, more capable amplifier fed by serious as hell mains.

 

Of course, this doesn't assume the scenario in which the noob completely destroys the driver in the VS18 in the first 10 minutes of operation because the system hasn't been made "idiot proof". Nor does it tell us what happens <20 Hz when any of the top 1,000 Movies With Bass are used as the input signal. Nor does it tell us what will happen to the sonic signature at the seats when different crossover points are used or if auto EQ is used with no measurement capability or if the system is not properly placed and tweaked before listening, etc.

 

We, using the cited example, just get the dB drag racers going on and on about the 0.2dB advantage of the VS18 over the Cap1400 from 20-125 Hz for 1/2 the price. People get banned, multiple threads on the subject are spawned by posters too lazy to use the search engine and any thread or post with serious discussion about the way subwoofers actually work in real world apps has cobwebs all over it.

 

In the case of a few people chasing after Nick to dis him and his product for personal reasons, the discussion doesn't even look at any of the facts. It's just an all-out attack on Nick and forum debating tactics become the arbiter of right and wrong...

[Bossobass Dave]

The HS-24 driver does not have the displacement of 4 LMS nor does it have the thermal handling or the upper end sensitivity. It is pretty close to the maximum displacement of 3 LMS which is a crap load of displacement no matter how you look at it. All of the numbers bear this out. It's a beast at moving air no doubt about it.

 

As most of us agree, looking at the burst tests above the displacement limited region are not indicative of real world situations since no one puts that much amp on a single driver. That being the case we can disregard the 50Hz and up burst data since we are talking about displacement. 10-31.5Hz bands are the primary focus for determining displacement. Neither of those drivers were using the whole amp in those bands so assuming that 4 LMS would receive the same amount of power as a single 24 and therefore only get 6dB instead of the full 12dB gain is a bunk comparison. We can make that comparison the way Dave has done with the power to the 4 drivers being held to the same amount, but if it is going to be done then it must be pointed out that each LMS would receive 1/4 the power and be required to do 50% of the excursion of the 24" in order to match it's SPL and would not be anywhere near their limits if employed that way. The 24 could be pushed to it's excursion limits with the same amount of power on the other hand. Also all 4 LMS's would be using the same amount of space as the single 24". It cannot be forgotten that the 24 cab is huge at about 16 cubes and that gives tangible benefits below 40Hz compared with an 18" stuffed into 4 cubes.

 

Another thing is that the amp used for the 24 was the K20, not the K10's which I've sold. On paper that is roughly 1.5-2dB more amplifier burst capability which will boost those upper end burst numbers for the 24 a bit over what they would have been with the slightly weaker K10.

 

Compare the voltages used to achieve the displacement limited burst output below 40hz of the 2 systems. Compare the sensitivity and maximum long term output data and the compression data.

 

I like the 24 I think it over achieved somewhat and it bettered what I had thought it would do in the measurements. I'm a fan. If I did an IB I'd go straight for them. It competes with or out displaces multiple good 18" drivers but it isn't magic where it is curb stomping 4 of the best measuring 18" drivers ever.

 

Thanks so much for bringing up the K-20 vs the K-10 vs the choices most DIYers opt for, etc.

 

Although I agree that there can be a side issue of the Xmax metric and how that may or may not relate to total displacement in actual real world use, that' aspect is all but irrelevant in this case.

 

I would most certainly use a K-20 or it's equivalent to power a multiple HS24 system, Vb notwithstanding. But, most would not and I'm elated to see the mention, as I've cited in my post above.

[Bossobass Dave]

I've had the advantage of being able to load a Raptor module with a pair of my BHT-15s, the TC Sounds LMS-R 15s and Nick's HST-15s. The system can be tested in-room with and without signal shaping in the chain, with different amounts of amplification, with different signal chain bandwidths and with performance measured several ways.

 

This is why we asked Nick to bring a pair of the HST-15s to the party last month.

 

We'll post what we've found out as time permits in this thread...

[Bossobass Dave]

As most of us agree, looking at the burst tests above the displacement limited region are not indicative of real world situations since no one puts that much amp on a single driver. That being the case we can disregard the 50Hz and up burst data since we are talking about displacement. 10-31.5Hz bands are the primary focus for determining displacement. Neither of those drivers were using the whole amp in those bands so assuming that 4 LMS would receive the same amount of power as a single 24 and therefore only get 6dB instead of the full 12dB gain is a bunk comparison. We can make that comparison the way Dave has done with the power to the 4 drivers being held to the same amount, but if it is going to be done then it must be pointed out that each LMS would receive 1/4 the power and be required to do 50% of the excursion of the 24" in order to match it's SPL and would not be anywhere near their limits if employed that way. The 24 could be pushed to it's excursion limits with the same amount of power on the other hand. Also all 4 LMS's would be using the same amount of space as the single 24". It cannot be forgotten that the 24 cab is huge at about 16 cubes and that gives tangible benefits below 40Hz compared with an 18" stuffed into 4 cubes.

 

First, if >50 Hz is to be disregarded, then why test >50 Hz and post the results and include the results in the averages at all?

 

Second, adding +3dB per driver is not bunk. It's fact. If you add a driver, you increase sensitivity by +3dB, not by +6dB. In order to say +6dB, you must specify adding +3dB of amplification... period.

 

Vb is irrelevant. Especially in this case. Please, put an LMS-U in 16 cubes and run your tests and show me where the advantage lies?

 

Well, actually, FIND an LMS-U first...

[16hz lover]

I find this thread highly educational, but I am also dismayed knowing that 75% of the people have never actually heard the 24. Yes,make it known right now that I am heavily biased in favor of the 24, I'm old and I've heard lots of subs in this life. In my younger days I use to read all the hi-fi Buyers Guides with tons of specs listed.  Then I started spending more time going to stereo shops (car and home) listening to every woofer/speaker I could find.  This revealed that specs were relatively meaningless in the real world.  What speakers do in actual rooms instead of anechoic chambers cannot be more opposite, and yes, I've spent some time in the one we had at McDonnell Douglas Aircraft.   To me, woofers have a personality( a soul ) that is visceral, and naturally different in every room.  That's what is so great about attending a Hi-Fi show and being able to listen to 100+ rooms of audio gear that I have read about in the magazines and finding out that the reviewers have very limited experience, especially in the world of subwoofers.  None of them have ever experienced the bass that Dave or Brandon displayed at their GTG's

   Criticizing, scrutinizing, and micro-analyzing a driver that you have never heard or felt, is rather unfair.  Just my worthless 2 cents, and I have my flame suit on, so blast away.

[Ricci]

First, if >50 Hz is to be disregarded, then why test >50 Hz and post the results and include the results in the averages at all?

 

Second, adding +3dB per driver is not bunk. It's fact. If you add a driver, you increase sensitivity by +3dB, not by +6dB. In order to say +6dB, you must specify adding +3dB of amplification... period.

 

Vb is irrelevant. Especially in this case. Please, put an LMS-U in 16 cubes and run your tests and show me where the advantage lies?

 

Well, actually, FIND an LMS-U first...

 

 

The raw driver tests are not tests of finished systems just like you just mentioned. They are to capture the drivers capabilities and help people formulate how to best employ them in a finished system design, including things like: What kinds of voltage and current capability from the amplifier the driver can realistically make use of, how to more accurately simulate the driver in various designs, if there is no holds barred on the amplifier power what types of levels can be reached in the range that is not excursion limited, etc. The upper end CEA-2010 bursts are more for car audio SPL competitor types 30-80Hz (I do get a number of emails and inquiries from these types and they are starting to notice this site slowly.). Which driver makes more efficient use of huge amounts of voltage in the upper range? It is just bits of information. A small component of a much larger picture. It is completely different looking at a HSU VTF15 over that range with an amplifier appropriately sized to safely operate reliably as a system and a raw driver test using enough amp to explode or cook the driver with one wrong signal, which is only looking at the driver and it's behavior in order to gather information that can be used to decide how to utilize it in what could be a variety of different system designs. Exactly like the VS18.1 results mentioned. (We've both discussed all this before and I've posted it numerous times here and there, but I'm reposting it because a lot of people still don't understand this difference between the raw driver or passive system tests and the commercial powered stuff.)

 

For practical output comparisons of systems I prefer to use the maximum long term output sweep myself. These are much more representative of what can be actually realized with an appropriate "safe" amplifier capability.

 

About the output comparison of the 24 and LMS. Yep...Can't buy LMS's anymore. Kinda moot at this point. Yes you get 3dB in sensitivity for each doubling of drivers. You are also halving the power to each driver and dropping the excursion requirements. If you appropriately power each driver the same as the first you get another 3dB for the full 6dB. The LMS is right about 89-90dB sensitivity in a 4 cube box over the 40-100Hz area. The 24 is about 92-95dB over the same. If you quadruple up the LMS you reach about 95-96dB over that range which is higher than the 24. The 24 still wins out decisively below 30hz. The CEA-2010 burst numbers for both drivers below 40Hz were nowhere near using the full K10. If we look at the maximum long term sweeps for both the SI was only requiring 100v and the LMS 120v. Considering both as a simple 4ohm minimum load we get values of 2500w maximum for the 24 and 3600 for the LMS. You don't need 4 K10's to power the 4 LMS drivers to realize their full displacement potential. You only need one K10, A14K, Sanway, SP12000, etc...I don't find that to be an unrealistic scenario. The 24 is limited by the excursion below 16Hz during the sweep with 100 volts going to it in that box. It could probably use a bit smaller box to limit excursion while the LMS in 4ft is managed pretty well. Personally I'd probably use something around 10ft or maybe even 8ft for the 24 and bring a bigger amp. When the 24 is driven to it's limit and the LMS is driven to it's limit the 24 has about a 9dB lead in deep bass output. So it takes about 3 LMS's to keep up with it. If that somehow indicates the 24 is anything other than a displacement monster I don't know what to think.

 

Also the sweeps do go under 10Hz I just don't present the data. So the 24 and LMS both received those voltage levels well below 10Hz. A continuous sweep from 2Hz up to 10Hz at those levels is brutal. It's not like WOTW's will present anything more strenuous unless the level is turned up more. As long as the amplifier does not put out more than the voltage levels indicated in the tests the drivers will not bottom out. If you start throwing more than 100 volts into the 24 in that box below 20Hz yes some things can get ugly.

[Bossobass Dave]

Awesome post.

 

Getting back to the claim that one HS24 can't swim with a pair of LMS-U, and adding in the discussion about the increase in sensitivity when doubling the drivers, etc.:

 

The LMS-U was a D2 configuration driver. If you double the drivers, you get +3dB increase in sensitivity but you go from 2+2=4 ohms to 4+4=8 ohms. You could parallel/parallel the 4 coils to arrive at 2 ohms nominal, but that's not a likely scenario and definitely would not have flown at the GTG. So, essentially, you gain +3dB in sensitivity but lose -3dB in required power.

 

This^^^ is partly what happened in the comparo at Brandon's GTG. The subjective results had nothing to do with FR at the seats or co-location of the 2 drivers. The HS24 was presenting dual 2 ohms resistance to the 2 amplifier channels while the pair of LMS-Us were presenting dual 4 ohms resistance to the same 2 amplifier channels. This is because dual 1 ohms was not doable by the amplifier and even at dual 2 ohms the amplifier could rather easily be pushed into protect mode shut down.

 

The argument about how much amplifier is needed is refuted by the actual real-world comparison, where amplifier power was indeed a factor.

 

So, in view of the practical application of the situation, the reasonable comparison would be a single HS24 to 4 of the LMS-U, or... additional amplifiers with the LMS-Us, which need to be calculated in the comparison.

 

That's the gist of my comments. A lot of things need be considered when talking about a subwoofer system to reproduce modern soundtrack source.

 

Like, yes, of course, using a smaller Vb to control excursion allows for a much better balance of use of the top end vs the bottom end in real world use. Applying signal shaping is directly proportional to using a larger Vb, as Ilkka showed by applying a +10dB L/T boost to the LMS-U. The larger Vb or the 10X power increase <30 Hz both limit use of the top end by too soon over excursion. Another 'minor' point in comparing systems with both dissimilar drivers and same drivers

[lukeamdman]

The CEA-2010 burst numbers for both drivers below 40Hz were nowhere near using the full K10. If we look at the maximum long term sweeps for both the SI was only requiring 100v and the LMS 120v. Considering both as a simple 4ohm minimum load we get values of 2500w maximum for the 24 and 3600 for the LMS. You don't need 4 K10's to power the 4 LMS drivers to realize their full displacement potential. You only need one K10, A14K, Sanway, SP12000, etc...I don't find that to be an unrealistic scenario.

 

I think this point is either misunderstood or not noticed at all by most.  In the vast majority of your testing, the K10 didn't even come close to full potential until 50hz and over.  Excursion/mechanical limits or harmonics become the factor below that point for most systems in CEA-2010 burst tests.  

I've been told many times that I won't reach a certain DB with whatever subs because I don't have a K10, but the fact is you don't need K10 power to over-drive a lot of these systems from 30hz and down.  

 

If I can xmech the 5400 in a Ghorn from 17-30hz with a cc5500, the K10/K20/SP2-12000 won't offer anything more in that range because the amp isn't the limiting factor.

[Bossobass Dave]

To reiterate, as it pertains to the comparison mentioned, IMO, you'll need more than a single amplifier to power dual LMS-U drivers. As I said, the standard choices are 4 ohms per channel or 8 ohms bridged.

 

The K-20 on a dedicated standard 220V/16A circuit will not power dual LMS-U drivers to maximum potential. That's going to provide, what, around 2500W per driver, peak power, and I guarantee you won't have to run too hot to see clip lights before the drivers clack when playing this vvv scene (for one example of thousands):

 

 

Now, if the load was 4 ohms and the K-20 amplifier was bridged and fed by 220V/50A mains... different story.

 

Both the HS24 AND the LMS-U were fed 3,500W at 10 Hz with both the CEA no-THD-limit burst and the max sine sweep at 10 Hz. In both cases, if you were forced to power dual driver versions with 2-channels into 4 ohms or bridged into 8 ohms (actually, 5 ohms at 10 Hz stereo or 10 ohms at 10 Hz bridged), you would be using most of a K-10 on a standard 220V/16A line.

 

Try that (4+4 stereo or 8 bridged) with the iNuke6K or a bridged IPR7500 or the CV5000, a bridged Sanway, etc., fed by 120V/20A mains, and let us know how it turns out.

 

 

[lukeamdman]

To reiterate, as it pertains to the comparison mentioned, IMO, you'll need more than a single amplifier to power dual LMS-U drivers. As I said, the standard choices are 4 ohms per channel or 8 ohms bridged.

 

The K-20 on a dedicated standard 220V/16A circuit will not power dual LMS-U drivers to maximum potential. That's going to provide, what, around 2500W per driver, peak power, and I guarantee you won't have to run too hot to see clip lights before the drivers clack when playing this vvv scene (for one example of thousands):

 

 

Now, if the load was 4 ohms and the K-20 amplifier was bridged and fed by 220V/50A mains... different story.

 

Both the HS24 AND the LMS-U were fed 3,500W at 10 Hz with both the CEA no-THD-limit burst and the max sine sweep at 10 Hz. In both cases, if you were forced to power dual driver versions with 2-channels into 4 ohms or bridged into 8 ohms (actually, 5 ohms at 10 Hz stereo or 10 ohms at 10 Hz bridged), you would be using most of a K-10 on a standard 220V/16A line.

 

Try that (4+4 stereo or 8 bridged) with the iNuke6K or a bridged IPR7500 or the CV5000, a bridged Sanway, etc., fed by 120V/20A mains, and let us know how it turns out.

 

I was powering dual sealed 5400s with a sanway, and below 20hz I clacked the drivers many times.  The amp was on a 120V/30A line but did have a 20A surge protector in line.  

 

With the SP2-12000 I'd have no issue at all powering dual 5400s in stereo wired for 1ohm each.  From what I've been told though, the SpeakerPower 12k handles both low impedance and voltage drop better than the 8k.  

[SME]

This discussion is painful to witness.

 

First of all, the claim that 1 HS-24 = 4 LMS-U is false from the get-go.  I have no doubt that the HS-24 performs extraordinarily, but it does not defy physics.  The statement implies a straight-up comparison between woofers without regard to the amp required to drive them.  To argue after the fact that this statement was made assuming both (1) that the amp was the performance-limiting component; and (2) that the user would not upgrade the amp to take advantage of the increased power handling capabilities of the subs, is absolutely disingenuous.

 

Furthermore, the difference in output achieved by doubling or quadrupling the number of drivers while keeping the amp capability constant in a system that was amp limited to begin with will not necessarily increase by 3 dB (for doubling) or 6 dB (for quadrupling).  This is a gross simplification as the results depend on the final impedances and the capabilities of the amp when driven into different loads.  The noobiest noob who believes as much is either confused or has been misled.

 

Undoubtedly, there's a lot more to sub system performance than the displacement capability of the woofers, but without any other context (such as the amps used, box sizes, and so forth), a statement such as "4 LMS-U = 1 HS-24" is flat out false.  I think the best course at this point for those who have made or defended such claims would be to admit their mistakes and move on.  Otherwise, you guys risk doing even more damage to your credibility.  It's sad that this issue arose in the first place because, as has been repeatedly pointed out, the LMS-U isn't even available anymore.  Even if it were, Nick's SI products would still arguably offer superior value in terms of performance for the dollar.  Is that not good enough?

 

Also, signal shaping is not the same as changing box size because the smaller box compensated with signal shaping requires more power to achieve the same low end performance.  Not only is a bigger amp required for the same performance in the smaller box, but the increased thermal demands will increase distortion.  This very point has already been discussed in the HS-24 measurements thread.  There are of course other arguments for using smaller boxes, apart from maintaining placement options and WAF.  Some here are arguing that smaller boxes reduce the likelihood of the amp over-driving and bottoming the sub at low frequencies.  This, in conjunction with a more modest amp, is likely a good design choice for consumer-oriented systems in which you want some robustness against abuse.  Of course, if the amp is big enough and especially if EQ/signal-shaping is involved to compensate for the increased low frequency roll-off of the small box, then the risk of damage is essentially the same.

[Bossobass Dave]

This discussion is painful to witness.

 

>>> <<< 

 

First of all, the claim that 1 HS-24 = 4 LMS-U is false from the get-go.  I have no doubt that the HS-24 performs extraordinarily, but it does not defy physics.  The statement implies a straight-up comparison between woofers without regard to the amp required to drive them.  To argue after the fact that this statement was made assuming both (1) that the amp was the performance-limiting component; and (2) that the user would not upgrade the amp to take advantage of the increased power handling capabilities of the subs, is absolutely disingenuous.

 

A dozen people, each in a different location in the room, heard a pair vs one HS24 with various input source. Adding a 3rd would be a waste of time (except probably to yourself and others who haven't made the comparison being discussed except on a napkin). So, as detailed earlier, 4 is necessary. Otherwise, the pair was completely and utterly overwhelmed. I argued nothing more than the facts that adding drivers increases sensitivity by +3dB and doubling impedance decreases output by -3dB.

 

You said it yourself... "...without regard to THE amp required to drive them." So, please be more specific, after your pain subsides, of course.

 

Furthermore, the difference in output achieved by doubling or quadrupling the number of drivers while keeping the amp capability constant in a system that was amp limited to begin with will not necessarily increase by 3 dB (for doubling) or 6 dB (for quadrupling).  This is a gross simplification as the results depend on the final impedances and the capabilities of the amp when driven into different loads.  The noobiest noob who believes as much is either confused or has been misled.

 

When comparing driver to driver, if amplification is the key component, one must specify that as a condition of one's prediction when multiplying the number of drivers on one or the other side of the comparison. The same holds true with Vb or whatever other variable changes might be assumed.

 

The claims made were:

 

"It's takes TWO LMS drivers to EXCEED the output of a single SI 24, as confirmed by data-bass measurements" "...in every desirable performance metric" "And probably most important, the LMS drivers don't have the inductance related frequency response issues the SI 24 suffers from..."

 

Do you read anything about impedance or amplifiers in those claims?

 

Undoubtedly, there's a lot more to sub system performance than the displacement capability of the woofers, but without any other context (such as the amps used, box sizes, and so forth), a statement such as "4 LMS-U = 1 HS-24" is flat out false.  I think the best course at this point for those who have made or defended such claims would be to admit their mistakes and move on.  Otherwise, you guys risk doing even more damage to your credibility.  It's sad that this issue arose in the first place because, as has been repeatedly pointed out, the LMS-U isn't even available anymore.  Even if it were, Nick's SI products would still arguably offer superior value in terms of performance for the dollar.  Is that not good enough?

 

Oh dear. Thanks for looking out for my credibility but that's irrelevant. How about you make the comparison in a real room using actual soundtrack source and report your findings? That always helps credibility, if credibility enhancement is the goal.

 

Also, signal shaping is not the same as changing box size because the smaller box compensated with signal shaping requires more power to achieve the same low end performance.  Not only is a bigger amp required for the same performance in the smaller box, but the increased thermal demands will increase distortion.  This very point has already been discussed in the HS-24 measurements thread.  There are of course other arguments for using smaller boxes, apart from maintaining placement options and WAF.  Some here are arguing that smaller boxes reduce the likelihood of the amp over-driving and bottoming the sub at low frequencies.  This, in conjunction with a more modest amp, is likely a good design choice for consumer-oriented systems in which you want some robustness against abuse.  Of course, if the amp is big enough and especially if EQ/signal-shaping is involved to compensate for the increased low frequency roll-off of the small box, then the risk of damage is essentially the same.

 

"...signal shaping requires more power to achieve the same low end performance..." "Of course, if the amp is big enough and especially if EQ/signal-shaping is involved to compensate for the increased low frequency roll-off of the small box, then the risk of damage is essentially the same."

 

Just quoting you here ^^^. The only difference you cite is additional distortion. Assuming you are referring to harmonic distortion, I think we've already had this go around about harmonic distortion and it's lack of relevance. I suppose you'll reopen this and I'll just refer to Ilkka's same argument where he put a single LMS-U in 75L and showed the increase in THD vs the same driver in 200L The difference in his CEA2010 average results from 12.5 Hz to 80 Hz was 1dB. The price for less HD <30 Hz was less output >30 Hz. No net difference and certainly no evidence that the measured difference <30 Hz is audible with soundtrack source in-room.

[Electrodynamic]

Dave. I called out Nick. He made statements in PI's thread that were clearly incorrect (doesn't understand percent vs fractions and went from saying throw any eq at it then changed it to '3db eq changes are normal'). All while being condescending to a poster. He's in a unique position where if he wants his business to do well he needs to be careful what comes out of his mouth.

 

I then called him out again when he started a thread touting the HS15 using info from this very thread where AVS was bashed. He wants to bash AVS yet use it as a platform to sell his product? Sure, go ahead, but I saw it fitting to let people know how he feels about the place. Again, he should watch what comes out of his mouth (keyboard) if he wants to do well.

 

I could care less what people think of SI or AVS. But I sure am annoyed by false information and rude posts to someone trying to help (see PI's thread).

 

BTW, I don't have all the back story, nor do I care to get it, but I think you don't have it all either. I believe people were saying two LMS18 had the same displacement (so ya, requires double the power to realize it) as a single HS24. I don't recall anyone saying hooking up two instead of one would equal an HS24. The bit I did see had Nick side stepping facts. Sure, seems like the haters were really picking out semantics and details, but it's not the gross misrepresentation of data you make it out to be. In fact, they seemed to have had the data correct (again, just picked to death).

 

I did not post anything in PI's thread directly at PI that was condescending. However, I did make information clear that was presented in such a way to elude to me being wrong.  Apparently you are one of the reason(s) why people stop posting on forums. No matter what you say you are taken beyond literal and nailed to the cross if you meant it any other way than what your text read. I can not help anyone that believes that "it can handle the boost" to mean that a driver can handle 300 dB of boost at 2 Hz. If one asked for clarification I would / could / did clarify but apparently that wasn't good enough. Once something is posted one time it is in concrete forever. 

 

[sarcasm]But thank you for making a PSA about AVS in my behalf. [/sarcasm] Where did I "bash" AVS in that post about the HST-15's other than mentioning that I did not see the images or measurements posted on AVS? I know the answer. I did not. Here is the text from my one and only post about the HST-15. Where did I "bash" AVS in my below posted text in my post?:

 

"Brought over from data-bass here are images which include measurements from the pair of HST-15's that I took over to Bosso's house a month ago during a GTG. I haven't seen any mention of it here on AVS so I figured I would post it for pictures if nothing else.

 

Naked and L/T'd close mic'd:

 

Video of the DO HST-15's in action:

 

After Bosso and Paul did their BASSIS adjustments:

 

Excursion:"

 

Thankfully, mentally, there is an ignore button on every forum. 

 

So in regards to the HS-24, by now are we agreeing to everyone pissing into the wind at the same time or do the LMS-U owners still get a free-pass?

[Bossobass Dave]

I was powering dual sealed 5400s with a sanway, and below 20hz I clacked the drivers many times.  The amp was on a 120V/30A line but did have a 20A surge protector in line.  

 

With the SP2-12000 I'd have no issue at all powering dual 5400s in stereo wired for 1ohm each.  From what I've been told though, the SpeakerPower 12k handles both low impedance and voltage drop better than the 8k.  

 

Most people who've owned the LMS-U driver have commented on it's being power-hungry. Ilkka tested one with 4KW, supposedly tested to be flat to 10 Hz (his bottom test frequency) and a true 4KW capable. They were invariably put in small boxes because of the extremely low Qts.

 

The Sanway is rated at 8KW bridged into 8 ohms. I assume that was your wiring scheme? Also, what was the net Vb for each driver? Did the clacking result in permanent damage to the aluminum cones? What were the dip switch settings on the Sanway, if you can recall? The Sanway never lit it's VPL or CPL lights? Was there any boost EQ in-line that you can recall?

 

Just trying to get the details for future reference.

 

The SP stuff is actually 2-full bridge configuration amplifiers in a single case. His comparisons of a full bridged SP amp (again, each channel is one) to a single half bridge channel of other amps (like Josh's K-10 or K-20), are disingenuous. Regarding the 1 ohm operation of a full bridge amp, I'll take your word for that but it would be nice to see the signal chain specifics and an impedance graph, O-scope screen caps and other pertinent data to go with the claim.

[Electrodynamic]

The raw driver tests are not tests of finished systems just like you just mentioned. They are to capture the drivers capabilities and help people formulate how to best employ them in a finished system design, including things like: What kinds of voltage and current capability from the amplifier the driver can realistically make use of, how to more accurately simulate the driver in various designs, if there is no holds barred on the amplifier power what types of levels can be reached in the range that is not excursion limited, etc. The upper end CEA-2010 bursts are more for car audio SPL competitor types 30-80Hz (I do get a number of emails and inquiries from these types and they are starting to notice this site slowly.). Which driver makes more efficient use of huge amounts of voltage in the upper range? It is just bits of information. A small component of a much larger picture. It is completely different looking at a HSU VTF15 over that range with an amplifier appropriately sized to safely operate reliably as a system and a raw driver test using enough amp to explode or cook the driver with one wrong signal, which is only looking at the driver and it's behavior in order to gather information that can be used to decide how to utilize it in what could be a variety of different system designs. Exactly like the VS18.1 results mentioned. (We've both discussed all this before and I've posted it numerous times here and there, but I'm reposting it because a lot of people still don't understand this difference between the raw driver or passive system tests and the commercial powered stuff.)

 

For practical output comparisons of systems I prefer to use the maximum long term output sweep myself. These are much more representative of what can be actually realized with an appropriate "safe" amplifier capability.

 

About the output comparison of the 24 and LMS. Yep...Can't buy LMS's anymore. Kinda moot at this point. Yes you get 3dB in sensitivity for each doubling of drivers. You are also halving the power to each driver and dropping the excursion requirements. If you appropriately power each driver the same as the first you get another 3dB for the full 6dB. The LMS is right about 89-90dB sensitivity in a 4 cube box over the 40-100Hz area. The 24 is about 92-95dB over the same. If you quadruple up the LMS you reach about 95-96dB over that range which is higher than the 24. The 24 still wins out decisively below 30hz. The CEA-2010 burst numbers for both drivers below 40Hz were nowhere near using the full K10. If we look at the maximum long term sweeps for both the SI was only requiring 100v and the LMS 120v. Considering both as a simple 4ohm minimum load we get values of 2500w maximum for the 24 and 3600 for the LMS. You don't need 4 K10's to power the 4 LMS drivers to realize their full displacement potential. You only need one K10, A14K, Sanway, SP12000, etc...I don't find that to be an unrealistic scenario. The 24 is limited by the excursion below 16Hz during the sweep with 100 volts going to it in that box. It could probably use a bit smaller box to limit excursion while the LMS in 4ft is managed pretty well. Personally I'd probably use something around 10ft or maybe even 8ft for the 24 and bring a bigger amp. When the 24 is driven to it's limit and the LMS is driven to it's limit the 24 has about a 9dB lead in deep bass output. So it takes about 3 LMS's to keep up with it. If that somehow indicates the 24 is anything other than a displacement monster I don't know what to think.

 

Also the sweeps do go under 10Hz I just don't present the data. So the 24 and LMS both received those voltage levels well below 10Hz. A continuous sweep from 2Hz up to 10Hz at those levels is brutal. It's not like WOTW's will present anything more strenuous unless the level is turned up more. As long as the amplifier does not put out more than the voltage levels indicated in the tests the drivers will not bottom out. If you start throwing more than 100 volts into the 24 in that box below 20Hz yes some things can get ugly.

 

Posts like this will go un-noticed or get buried and forgotten. Josh took the time to explain, in detail, the differences yet the latter will never be looked at or taken as true information on other forums (not naming names so don't go crazy on me tuxedo!  ). Such is the real juxtaposition with the HS-24: First it was "BEAST's GTG results means nothing, send it in to Ricci". I sent an HS-24 and an enclosure to Ricci to which he measured it and posted the data. Then the information was misconstrued and posted adamantly about two LMS-U's being able to not only keep up with, but BEAT, a single HS-24. Josh's post clearly explains why the latter is not the case. But as tuxedo mentioned maybe I'm the one that can't do percent vs fractions. 

 

To add more to my, still, claim that it takes 4 LMS-U's to keep up with / out-perform (I'm sure that select people will tell me which of the latter I have said in the past) is that the LMS-U is a linear topology woofer and the HS-24 is not. Linear topology woofers are perceived by the human ear as having less output than their overhung competition. For the same actual SPL the linear topology woofer will sound quieter due to the reduction in non-linear BL induced harmonic distortion found in overhung topologies with the same / similar one-way linear excursion. If you own a Term Lab you can accurately measure the SPL from both systems and see for yourself. Three or four LMS-U's will be able to over-drive an OmniMic system so you will need a more accurate high-SPL system such as a Term Lab or carefully calibrated REW system with a properly good / proper mic. 

[lukeamdman]

Most people who've owned the LMS-U driver have commented on it's being power-hungry. Ilkka tested one with 4KW, supposedly tested to be flat to 10 Hz (his bottom test frequency) and a true 4KW capable. They were invariably put in small boxes because of the extremely low Qts.

 

The Sanway is rated at 8KW bridged into 8 ohms. I assume that was your wiring scheme? Also, what was the net Vb for each driver? Did the clacking result in permanent damage to the aluminum cones? What were the dip switch settings on the Sanway, if you can recall? The Sanway never lit it's VPL or CPL lights? Was there any boost EQ in-line that you can recall?

 

Just trying to get the details for future reference.

 

Yes, I had the Sanway bridged and running a final 8ohm load.  Net volume after bracing was right in the 4cu.ft ballpark per driver (4.55cu.ft before bracing).  The dip switch settings were always at max voltage, which was something like ~198v?

 

I would only hit the VPL lights in the 50-65hz region where I applied some boost because of my old horrible room, and I had to be cranking it to the limits to do that.  No boost/EQ lower than that.  

 

I also remember thinking the 5400 was power hungry, but after owning them for a good 4 years now I don't think that's an accurate statement anymore.  I think people think it's power hungry because of it's tremendous thermal handling and excursion capabilities for 30hz+ content (think metal or dubstep music).  With a 2kw amp they will make some serious noise, but if you feed them 4kw they really shine for that kind of content.  People upgrade to that 4kw amp and think the driver is power hungry, but that power can only be used over 30hz.  

 

Because of the power of the motor and how flat the BL curve is to pretty much the xmech of the driver, 4kw below 20hz will be detrimental to the driver.  The motor is almost too powerful for it's own good.

 

Xmech on the 5400 is where the back of the cone starts tapping the top spider.  When it first starts to tap, the driver isn't in any danger, but you can push farther and mushroom the cone if you're stupid.  I've never pushed past the initial and VERY obvious warning signs to hurt the driver.  You really have to be careless to break one.  

 

There have been 3 or 4 versions of the 5400, where the latest versions has a thicker cone and finally they slightly reduced the spacing between the two spiders to add some clearance on the final revision.  My version is the second to last model that has the thicker cone but not the latest spider spacing.

[Ricci]

I agree with Luke. The LMS is actually quite efficient in my opinion compared with most other drivers with similar xmax. Since the motor maintains a very large percentage of it's full strength while driving the coil all of the way through the gap to the point that the cone contacts the spider landing, it is just as efficient at high power levels as it is at lower ones. This is something not captured by a 2.83v sensitivity spec. It also has a significant BL^2/RE to go with it.

 

Power hungry? Let's talk about the split coil XXX. Power hungry slugs. If only they would have gotten that much stronger neo motor done...That's why I like the ZV4 and HST drivers. More motor and efficiency than the XXX's, way more mechanical headroom and abuse tolerance than the LMS. Not quite as linear as those 2 but still a crap ton of stroke, slightly lighter than either and cheaper though. Available! (#1 reason.)

 

I've never really commented on that infamous GTG but I have a number of hunches about why the results were the way they were subjectively. I'm not surprised that the 24 shook the room more and seemed more powerful.

[Bossobass Dave]

Well, yes, I call 4KW per driver kinda power hungry.

 

BTW, the Sanway amps VPL dip switch numbers are doubled when in bridged mode so if the VPL lights were lit with 50-65 Hz input into a pair of LMS-U the amp was putting out 6KW per driver bursts to make the drivers really shine and the VPL lights light up.

 

I would like to hear comments on the difference between the pair of LMS-U and the single HS24. Subjective responses have always fascinated me but I have no way to quantify them because the discussion is usually pretty juvenile with loads of exaggeration about teeth and pants.

 

The impedance was halving the power to the pair of LMS-U and that's usually the difference that matters with soundtrack source. Looking at the speclab cap where one was switched to the other on-the-fly during playback of one of those Bass I love You types of music clips, you can see the SPL difference of right around 3dB and no significant difference in FR in the bandwidth of interest. You can also see the slight advantage the LMS-U drivers enjoy around the 100-120 Hz region due (maybe) to less inductance-induced roll off:

 

 

IMO, the 3dB diff in level was not what I was hearing as the difference. There was a significant difference in presentation and I do not believe it was harmonic distortion and none that would be significantly audible shows up on the SL cap either.