Hey Ricci... - Page 2

To elaborate a bit...What I was getting at with the comment about $50 12's was that if you play the bang for the buck game you can end up with some sick things for cheap. John mentions using 4, 9mm xmax pro 18's against a single XXX. Of course the 4 pro 18's win overall. Is this a question? It is 4 drivers versus one. By that same token I'd take the 16 12's in the above example over the 4 budget pro 18's without hesitation. Something like 12-16 12" drivers against a single 18 is no contest every single time. However at some point you have to make the call on just how big of a system you can deal with though.

The question is if you can fit the 4, 9mm xmax, pro 18's do you go with those or do you need a driver with more displacement like 25mm for when you EQ the low end in which case you sac some efficiency? We can talk about the advantages of efficiency all day but I personally need the later.

I use 4 XXX's currently in 9 cubes each sealed with about 4500w per driver. One in each corner of the room. Truthfully this is more than enough. I do not have any issues with running out of headroom except when I purposely push the system to uncomfortably loud demo levels. When I do run out of headroom it is in the sub 25Hz range first due to the sub bass boosting done to get the response flat. The excursion gets scary and the drivers grumble first which tells me to back off a bit. I can make my coffee table literally jump around on the floor at certain frequencies under 20Hz at these types of levels. (Wood floor over crawl space). I never have issues in the range where the way more efficient pro drivers would have their 10dB advantage. Yes even with the incredibly innefficient XXX's, 4 of them and big amplification is still enough to do a lot of damage in a domestic environment such that I never find myself running into headroom issues in the music bass range.

Now I never claimed this bass system as "the best", or something to emulate or any of that. If I had it to start over again from scratch would I go with something else? Probably. Also my subwoofer section is far from complete anyway and I've been spending the last year trying to decide what to do with it to finish it off. Some of the DB testing is related to this search. See I built my enclosures with dual opposed either 18's or 21's in mind from the beginning and that is why there is a removable baffle on both ends. I had thought that I would replace the XXX's with a pair of 21SW152's or 21nlw9600's and get the extra 10dB of headroom in the upper bass plus perhaps a little extra displacement but after testing a couple of 21" pro drives it really does take 2 of them to almost equal the low bass output of one XXX. My favorite driver I have ever used probably is the big B&C BTW. Also those a very expensive drivers and I need twice the number of them to just maintain parity in the deep bass with what I already have and am happy with to begin with? Not to mention the biggest improvement is in a range that I don't currently have headroom or distortion troubles with anyway? That just seems like spending a whole lot of money for...? What I really need is even more displacement and if I can get extra top end at the same time, great. I thought I could re config the enclosures and go to 4 21's per enclosure but now we are talking crazy money. Not in the cards. Then I thought I already have 3 LMS's so I'll just sell the XXX's and use the proceeds to buy 5 more. Again that is a lot of work to sell the XXX's and recut the baffles and it still ends up costing a good chunk of money. Only a moderate gain in displacement. Meh...Then I thought about 8 Zv3's or 8 FTW21's but that has most of the same problems as the LMS route. Cost, work and having to sell the XXX's which I think will be a PITA.

Currently I'm leaning towards saying to hell with it and buying 3 more XXX's pulling the one wasting away in my garage from the ported enclosure and just slapping those 4 in with the current 4. It would be the least amount of work by far requiring only cutting the driver cut-out in 4 baffles and I would gain the most potential displacement. Not only that but even with the extra power from the amps I should at that point be amp limited everywhere. I will never have to worry about over excursion or damage to drivers ever. I do not see there being any headroom deficiencies in any realistic scenario if i go this direction either. Anyway that is the reasons why I ended up moving away from the high efficiency units for my HT sub bass duties in case anyone was wondering why I have ended up back with the inneficient boat anchors that I started with. One mans particular situation...YMMV and all of that.

40Hz and on up I'm a huge fan of the pro high efficiency drives and I think they beat the snot out of the innefficient car audio and consumer grade stuff, which is why you'll see me using big mains and big mid woofers. I bought in for 11 drivers in the AE deal. 9 are 4 ohm TD15M's with Apollo. The current crop of big pro woofers are closing the gap but still just don't quite have enough VD for the sub 30Hz freq's without resorting to large groups of them.











Oh and Scott....
4 2226's per main don't you think that is a bit excessive? You can't possibly need that. I've been running a pair of 4645C's which have 2 in each in a very large room at sometimes absurd levels and it is more than enough. Good god man. I'm only going to run a single 15" driver per main! Sell half of them to fund the finishing of the project.

Think of two tubes with the same wall thickness. Let's say one is a half inch tube and the other is a 3 inch. You glue both to a flat surface at one end and cut them to the same length. Which one will flex or deflect from center with less applied force? Which can be snapped off at the glue joint easier? Which tube will be easier to bend over your knee? Not real scientific but...

Less coil mass and layers= less motor force. The gap can be made smaller but then we are talking about very long excursion designs so there will be more chance of rubbing, misalignment, etc. The longer your excursion the wider your gap needs to be for clearance usually. There is a rather big gap in the XXX which is part of the reason it has such a low BL despite having a huge motor.

Heh. Who needs two, four or eight high powered 18's in a single system?

The main design point was longevity. I wanted to build a system where I could be happy with it for the rest of my life (I'm 27) and not desire to "upgrade" (lol, which I prolly will anyway) but moreso not be hit by that wall of "I can't turn it up anymore cuz it's got nothing left". I want to to not be able to turn it up because my face will be peeled off if I do. I want that kind of performance. Again...why? Longevity, headroom ...all the good stuff. Also, everyone always seems to run out of steam with mains and I wanted to eliminate that possibility. On demand, if I desire a real rock concert at home, I'll have it. Now... the why 4x and sealed? Well...



I don't want some arbitrary cutoff for my mains. I want to run them full range. For the most part, at equal power twice as much sealed will equal the output/extension of the vented version but with extra output up top and down, down, down to the very bottom. I don't know anyone with a system like it. Everyone builds kits. This is DIY and I wanted to build something unique and very special yet extremly capable. Time will tell if I make or break. Thankfully a downsize will net me some extra cash. Win Win!


What most people are missing is that not only are these going to be extremely capable mains but also a mega MBM for the LFE system.

I'll be writing an FAQ to go with my build thread to explain all this, hopefully in much detail. Sorry to derail thread. Carry on.

EDIT: Oh Josh..btw, you should totally just stick with the multiple sealed XXX's. Just get more. Sounds like you are good up top.
Edited by Scott Simonian - 6/26/12 at 10:52am

Scott,

Pffft...This entire thread is a derail to begin with. By all means talk about whatever. I didn't start it but it has my name so yeah. I'm giving the ok.

I think I am just going to continue with plan alpha for sub bass. It's not like I'm dissappointed with what I have. 4 is already enough really but I intended 8 of something from the get go and I already have an extra sitting there.

I forgot you would be running those full range. Are you planning on running double bass or are the RLP's going to handle LFE only and not be active with music? Are you going to let the 2226's naturally roll off or equalize them flat? I just let my subs handle everything below the crossover. I've never really liked double bass when I've tried it.

I don't see how the above applies here.

The only transverse forces are gravity and transverse components of rocking modes, neither of which are a function of VC dia.

Motor force = I*L; the longer VC with fewer layers just redistributes the same length of wire differently.

By smaller gap I meant that fewer layers takes up less radial space than more, but you're right that more excursion needs more radial clearance, so my hypothesis loses a point there.

They may not be functions of vc diameter but they act upon the former the same. A smaller diameter tube will be easier to flex, apply more sharply focused force to the cone and have a weaker glue joint. The forces involved are not entirely linear or symmetrical and get increasingly less so at larger strokes. I'm probably overstating this stuff quite a bit but I'm trying to give some reasons as to why we don't see voice coils of this type very often.

Heheh.. okay. Cool. Thank you, sir!

Yes. You pretty much have the details correct. Thanks for paying attention. I won't name names but I do have a few fans that have been waiting ever so patiently for the outcome of my uber build so I'll outline some details. Those that agree/disagree feel free to nitpick. I'm doing it the way I want anyway.

AVR settings:

+Left, center, right will be full range
+Surrounds (4x) will try at default 80hz or may play around. They are sealed but very small.
+LFE LPF will be set @ 120hz
+LFE will be set to double bass which will reproduce the LCR's bass info in addition to it's own LFE signal. This is pretty much how everyones system works but almost everyone has some HPF on their mains. I will not.
+Audyssey XT is an option but I usually don't use this. It is an option though. My Onkyo TXNR3007 does have independant levels and delays for 2x LFE out but with AudXT it will not EQ them seperatly, or at least I've heard. This is one of the very limited amount of XT AVR's that has truely independant 2ch LFE. Though I think Aud XT just treats them as one sub wrt the actual EQ part. Not delay and levels, those are variable. Awesome! This feature will play HUGE in the next part.
+Actual subwoofers will get direct output from AVR to proposed Bosso bass EQ for bass boost and hopefully overall extension <5hz

DCX controls:
+Crossovers....blah blah blah
+Each LCR get's a dual channel bass output. I mean like a .5 system with the bottom woofers maybe playing up to 120hz and then roll off and the upper woofers playing to ~300hz. Hope that makes sense.
+Each channel gets it's own DCX. That means three inputs and six output. Four outs used per LCR with two free per DCX for upgradability (bolt-on super tweeters and/or extra subs used throughout room.)
+Each L
+Sum feature will be used for each LCR combining the relevent channel with a copy of the LFE out from the AVR (will most likely use output #2 from AVR for independant level and delay calibration)
+The possibility for shelving bass with LCR's is there but I will run them natural at first.

Not a perfect outline but that pretty much sums (pun intended) it all up. Yes, if you are paying attention the LCR's will get a double (pun intended, again...Wooooooo!) dose of their own bass. Yeah, so what? It might sound cool. It might sound awful. We will find out when I'm done but if one must say anything regarding some form of cancellation, blah blah blah. I will have full control over EVERYTHING so I'm sure I can get it to work.

Mmkay. I think that was everything.
Edited by Scott Simonian - 6/26/12 at 11:39am

Got a good laugh seeing the XXX graphed to 2k Hz.

Chop the graph at 200 Hz and apply a L/R 4 LPF at 80 Hz, as most everyone does.

The so-called high sensitivity version will look like a bandpass sub, and, IMO, if it's sensitivity peaking at 60 Hz you're after, just build a BP sub.

Of course, building for efficiency at 60 Hz, then pulling the response down at that very same point is kinda silly, no?

Again, there are no significant (transverse) forces tending to bend the tube; axial forces are another matter of course.

The reason we don't see such a design is because there isn't a market for very expensive and heavy woofers (because of the extra magnets) that only give higher sensitivity where it's not really an issue.

The reason why is cuz if I do that then my much more capable (at lower frequencies) quad 18" sub system will not be reproducing any possible deep bass that isn't carried in the LFE channel. This way, all four 18's and twelve 15's will do all the bass <120hz. The only side-effect is the "doubling" of mains bass back into themselves. This can be controlled with levels and/or turned off completely at any time though. The crazy amount of control I'll have with these DCX's is awesome.

All these things can be toggled on and off with a switch or button press. Oooo I'm so excited to get this done!

Noah,
I don't see prohibitive weight and cost as being the reason at all unless we are thinking of different goals. I am assuming we are talking about making a driver with pro audio type 95+dB sensitivity up top but a geometric xmax of 25-30mm. If this type of driver was easier to produce with a small diameter coil it would be in production. This is the type of driver that everyone wants to develop because it produces more bass in less space.

Existing driver motors are already providing as much stroke as the typical soft parts and frame can handle so switching the voice coil mass into an elongated form providing even longer strokes but with smaller diameter doesn't make sense. This will probably not have much effect on the moving mass since the former is smaller in diameter but now has to be longer. Not only will the driver components not handle the increased stroke without tooling new parts but the coil would not handle the increased thermal demands needed to use it.

From the phone...

Scott,

You are doing something different that is for sure.

An active 3.5 way with your mains? I'm curious why the extra complexity over a standard 3 way, improved C2C spacing through the midbass? Your spacing from the bottom woofers to the mid horn is what 40" give or take and your XO to the 15's you plan on being 350-400Hz? 3.5 way requires an extra 3 channels of amplification, equalization, cables, extra time tweaking etc...Might be worth trying without the added complexity just to see how much of an audible difference is there.

Listening distance is about 10ft?! WTH man. You are going to use about 2% of these.

You are running the LFE channel into the mains as well as the RLP's? Is that right?

Max had a good point. One of your biggest challenges will probably be hiss and noise floor. You are going to want to keep the amp gains as low as feasible and use as much gain as early in the chain as possible. Gain structure will probably be a whole day or two by itself with this monster.
Edited by Ricci - 6/27/12 at 8:09am

^^This^^

Widen the gap, use 3dB more amplifier, drivers are safe, displacement remains intact... what's the question? All this sensitivity/efficiency crap is just that. I also agree with your simple statement of fact regarding 40-80 Hz. What the disconnect here is, I just can't understand.

I would just love to see some real data posted in-room using these pro sound drivers. There isn't any, as in none. WinISD is a kid's toy. Useless. There's all this talk about pulling the top end down by -6 to -12dB, but I've never seen anyone do it yet, much less do it and prove this goofy 'headroom' theory with any sort of in-room test results data using actual real program source.

People who use pro sound drivers tout how loud it can get and when you attenuate the <30 Hz response, they call it 'tight'. So, why have subs at all? Just beef the ported mains and run them large, erase the first 3 octaves and enjoy.

The only thing I disagree with in your system is the ridiculous size. No chance in he!! I'd live with 80 cubes of box for the low end.

80cubes....No no...Me neither!

It is 36 cubes for all 8 drives. Still a lot of box no doubt!

Each pair of 18's will be in 9 cubes dual opposed. Doesn't model that great on paper. A little peaky, efficiency is tripe and the q is high but that is what active signal shaping is for. I was hoping for IB to get the boxes out of the room totally but its not in the cards. (It's funny how priorities get shifted around as you start home shopping. )This way with 3kw available for each driver they will never even exceed 40mm so I will be completely amp limited and the drives will be still in their comfort zone. I can thrash it to my hearts content and as long as the amps hold up I should be ok. I am a little curious how the new room is going to be acoustically and structurally since I am coming from a wood floor and framed walls to a concrete basement floor with 3 walls of brick. I expect to lose a lot of the tactile feel.


As far as running the pro drives sealed at home...Don't get me wrong they sound amazingly good and they will rip your face off in the kick drum range but at the end of the day in my case at least, when I push my system I run into headroom issues in the sub bass range well before the upper end so the extra 5-10dB of sensitivity is not applied in the area that I want the extra headroom and would probably never be utilized. YMMV FWIW etc...
Edited by Ricci - 6/27/12 at 8:43am

When I used to visit the forums at Prosoundweb I got the impression that weight and cost were both important to pro guys.

To them it's a living, not necessarily a passion inspiring extreme behavior like you see around here.

I'm no expert on motor design, either; is the basic premise even correct, that stacking more magnets to give the same flux density over longer excursion?

And I forgot, there's another reason that thisshould increase efficiency, I'd guess more than the wider radial gap - for a given overhang, the longer the VC is, the less the % of wire there is out in the air doing nothing.

[quote name="Ricci" url="/t/1417211/hey-ricci/0_50#post_22171088"Existing driver motors are already providing as much stroke as the typical soft parts and frame can handle so switching the voice coil mass into an elongated form providing even longer strokes but with smaller diameter doesn't make sense. This will probably not have much effect on the moving mass since the former is smaller in diameter but now has to be longer. Not only will the driver components not handle the increased stroke without tooling new parts but the coil would not handle the increased thermal demands needed to use it.[/quote]

I have been reading up on the subject and it's still probably one of the biggest things I'm worried about. That and a lack of power from the wall. Most of the amps will be set low enough and hopefully it won't be a problem. Let's hope.

Again, these monsters look larger than they really are. Yay! Each woofer is in it's own sealed box that measures 16.5" by 16.5" on the front. So the stacked cubes per channel are 33" tall and wide. The midhorn is 12" entirely and iirc the JBL 2380 is 11". The C-C from the top woofer to the midhorn is more like 12" or so. Bottom woofer to top HF is a bit over 24". The important part is that almost all the spectrum comes from the midhorn/hf section which is pretty damn small. Only the 300hz and down comes from the woofers. I tried to make the centering between all as tight as possible. And you know...I'm really not worried about the spacing. Look at any ACTUAL JBL design or anything similar and you'll see even larger C-C distance (granted the listening position may be further in actual use) and no one is concerned about it. Look at MK's old JBL systems. Mine are much tighter. So...I really don't think about it cuz I've got this design real tight.

As for the 3.5way design. It was an idea to have the capability incase of cancellation ...blah, blah, blah. Just fyi, I already have the means to have it done and it's paid for. A stereo amp for bass and I have a smaller stereo amp for the mid/hf section. With a dcx on each channel, I've got the goods. At this point the question would be "why didn't I allow myself to run them with independant bass control?". I do plan at first to just run the system as a 3-way anyway with all four woofers running from xover all the way down. I just thought I may need to roll one set off up high so I've got that functionality built-in. Ahhh...I f**king love the DCX.

Yup. LFE in mains and RLP's. I'll never have to worry about adding an 'MBM' ever. Lol!

Scott,
You would not worry about an MBM with just one 2226 on each speaker. My C-C spacing was all from JBL and within 13 feet all were fine! Even those 4675C's which had a huge horn, I mean huge!

Exactly so I'm not worried. You and I have similar sized rooms and seating distances so I used your experiences as an A-OK for what I wanted to do.

Your different systems, James, had me plenty inspired to design this monster set up. Yup.

Sorry... I thought you said each in 9 cubes.

As far as being limited on the extreme low end, I've never seen a system that isn't. Even with 8xLMS and a scrillion watts, notnyt filters at 7 Hz, the 1st octave being traded for SPL above that. That only means that his system is limited in the 1st octave or he wouldn't filter... simple as that. Sub bass is where the focus should be. Above 30 Hz is backstroke.

If you have a dozen pro sound drivers just for 30-100 Hz proponents talk about headroom. And if you add a dozen more, adding +3dB "more headroom"... sorry... nothing changes except you're out the dough for a dozen drivers and you can't move for the added box space.

The same truth applies when you use the pro sound stuff for sub duty. Pulling down the top end does nothing for headroom. When the low end reaches its max, that's your headroom ceiling. Back off of there or, at worst, kill the system, at best, kill the SQ. What's left on the table at the top end is not headroom, it's table scraps.

In my opinion, backed by placing and measuring 50 or so systems in half a dozen rooms, a 4x15" multi-KW, signal-shaped system is all anyone needs. Double that to 8X15 with +3dB of amp and you have headroom from whatever to whatever. there is no lacking at cross. The whole "130dB" sh!t is just absurdity, as is running the SW output at 10-15dB hot. Fun, personal preference, demo mania, call it whatever you will, it most certainly is not necessary, and... it is always clocked above 30 Hz and always at the expense of below 30 Hz.

Here's a comparo of an 8x15 system in my room vs notnyt's 8x18 system in his room, using sine sweeps. My sweeps were started at 3 Hz and his were started at 10 hz:



This is simply enormous playback capability with no compression. In fact, I question how he could stand running that top sweep. I stopped where I did because it's insanely bad for everyone and everything and not necessary. In the past when I've gone to +6dB of system (doubling amps and drivers to 16x15), I noticed zero playback difference at reference level, calibrated flat. That's only useful if you prefer to push far beyond reference levels, which is a personal preference and has nothing to do with accurate reproduction goals.

The point here is that the driver/small box combo I used in these sweeps should be far less "sensitive" than the combo not used. If you compare WinISD models, you'd wince looking at mine vs his. But, in-room there is virtually no difference other than how loud a sweep you can perform without system damage/stress. Neither of us had to pull down the top end and neither of us is looking for added headroom in the top end.

Now, we just need someone with accurate hardware to run the same test using pro sound drivers, signal-shaped flat as ours were, to at least 10 Hz, and bingo, we'd have a post on the subject with some credibility.

Good post, I wish I learned spec lab when I had the CHT subs. Notnyt said he was not limited, he just could not feel the presence of under 7hz even at 130 dBs. That is what he said, not my opinion. Of course, when you can run 130 dBs at 7hz I don't see the need of filtering under that for movies which won't come close those spl's, why need more headroom above 7hz? I know when I get crazy and run the system hot and pin the meter it starts to hurt my ears, I don't run it that hot anymore, actually with the new drivers, I have been watching movies with the subs calibrated to 71-73 dBs and feel more.

This makes me sad, as that is exactly where I am with my room :/ and I refuse to go with bass shakers/face shakers.

I could be mistaken (and it's not really a big deal) but aren't you "cheating" a bit with that statement? Don't you use an L/T to pull up the low end though... functionally equivalent to "pulling down the top end" ???

Hopefully there is still something there...That will suck if it is completely gone. What I liked was I could watch a movie at a reasonable level so as not to disturb everyone else in the house but I could get a sense of powerful low freq's just through the furniture and floor. I too will not be using tactile transducers. I just can't. No judgment for anyone that does. On the other hand my current room is plagued with some major acoustic issues so hopefully there will be some improvement in that regard.

For you guys with basements and concrete floors would installation of a floating floor bring back some of the tactile feel? I know it's mostly for sound isolation to the rest of the house but wouldn't the vibrations still be transmitted on the floor which is floating, just not to the rest of the house?

I am really not sure if that's the case but it seems to make sense.

I'd argue that definitions of pro, car or home audio woofers have become rather fuzzy lines in the past few years. A woofer has parameters and strengths which are or are not useful for a given application.

It is important to be mindful of how much electronic correction is required and how much output results from say 1/100th to 1/10th maximum power at different frequency ranges. I don't believe there is some magic cliff of EQ beyond which any more will make the system self destruct. I do feel there is a sliding scale of compromise, and the more you push it, the more you need to check the real world results. Generally you will be able to find lower distortion and better suited options than say 4-8 pro-style 18" woofers if you look at other options in the same total sealed box volume.

Just take a look at the maximum output measurements Josh took recently of the Paradigm Sub 2. These pretty well track what is likely the pre-EQ response of the 6 10" woofers in the relatively compact package:

There's a world of difference, IMO. When you L/T the input signal, that boost is there for <30 Hz only, which is the occasional program source. When you pull down the top end, it's a permanent 'fix' that affects the entire program source and the crossover region. It's far more difficult to do with good results in my experience. In fact, I believe most people who have used the pro sound driver approach have ignored the whole 'pull down' part of the equation and just applied post smoothing EQ. And, don't forget the dreaded Audyssey effect. With adjustable L/T, low end boost is no sweat with Aud, but with top end attenuation, the low end is defenseless.

LTD's comparo is what's a bit skewed by taking the least possible sensitivity driver and comparing it to the highest possible sensitivity driver... times two. If he compared the LMS Ultra or the UXL-18 to whatever the 18" pro sound flavor of the month is, you see a much more probable comparison.

Here's Josh's results from testing the B&C 21 vs UXL-18 (BTW, Josh, most awesome stuff there, and getting better every time!)



I included the PAIR of 21s vs a single UXL-18 max burst numbers to show that, using LTD's premise, it takes 2-21s to equal 1-18 down low before his point is realized and before you pull down the top end. Since I would apply a +8dB L/T to the UXL-18 to work with a typical room, you'd have to pull the top end of the 21s down by around 12-15dB to get equal in-room performance.

Again, I have far less experience with top end down systems because i saw it as a lesser approach and abandoned it 15 years ago, so it would be great if someone would post more than a WinISD model and show some actual data.

You and I have touched on this subject several times in the past. Yes, this is a familiar commercial solution to utilize top end 'headroom' by using limiters to stop the low end signal at max headroom. And, yes, this gives the effect of reverting the system to its pre-signal shaped response. IOW, using limiters to negate the L/T.

It's just a poor design. They should have to disclaim any posted FR graphs and/or specs accordingly.

I thought that's what you were referring to, bt i just couldn't get you to spit it out before.