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Ficar SSD18 Group Buy Thread - Page 9

post #241 of 535
Quote:
Originally Posted by Ricci View Post

Dave,
I haven't yet came to a conclusion on this one particular B&C in a sealed alignment. I only brought it up in this thread because of the suspension stiffness result not to directly compare the 2.

Using the same size of sealed enclosure for all parties involved there won't be more than a couple of dB sensitivity advantage for any drivers down low so I consider sensitivity there moot. If you want more you need to add systems or use a different alignment. What matters there is displacement, self noise and power handling. I've seen you tout the advantages of having the box control excursion before and how the extra power available can be used for large dynamics up top. I agree with this. You don't believe the same holds true for efficient pro drivers though because they have too much headroom up top? I disagree. At what point does too much efficiency kick in, in your opinion? At what F3 is the basic response shape unacceptable?

I agree, and have said basically the exact same thing, except the "sensitivity there is moot" part (see below).

My limit for boost is +10dB. Looking at 'most' rooms, PVG doesn't kick in until around or just below 30 Hz. That means you need to be flat to that point anechoic. So, my limit for roll off at 20 Hz is right at -15dB. If you choose to cut the top end in the case of a driver like the B&C (or JBL or whatever), you look at displacement. The top end you cut is not headroom, it's tossed in the waste basket.

So, yeah, you can buy 3 or 4 of the $1k pro sound woofers and get that headroom @ 20 Hz, but that makes as much sense as buying a tractor trailer to deliver a pencil.

Look at it another way...

If you watch a movie at reference level and your system operates cleanly across the board at that level, then essentially, use an all pass filter to 'cut' the entire systems BW by lowering the MVL to -10, how do you have headroom? You have headroom in the sense that you can safely bump the MVL by +10dB if you choose to.

OTOH, if you cut a subs top end to get the required response, your headroom is at 20 Hz, not 100 Hz. You don't have the same option as in the illustration of the entire system. When the driver or the amplifier bottoms at 20 Hz, there is your headroom ceiling. If you attempt to utilize the 'headroom' at 100 Hz by bumping the SW trim or MVL, you'll exceed maximum capability <20 Hz.


Quote:


The reason that I don't care whether the response rises all of the way up until 125Hz is because this results in an extra 6-10dB in free output headroom that can simply be cut without much ill effect. At 20Hz the difference in sensitivity is going to be maybe 1 to 2dB at most. And actually the advantage in sensitivity should go to the opposite driver than you think despite what the FR shape might at first glance look to indicate. Lower F3 doesn't automatically mean it is more sensitive or efficient at lower frequencies. If you match the 2 different types of systems to the same output levels and response shape in use. The "pro" unit uses no more boost or very little in reality. What it does end up with is a huge cut in overall top end output comparatively. Yes much more signal manipulation is needed but if it results in large cuts in overall output I consider that an advantage personally. This assumes that the displacement, power handling and self noise is acceptable on the high efficiency unit which are what the real question marks are with those types of drivers and where most of them can't make the grade.

Sensitivity (and displacement) @ 20 Hz is not moot, it's everything. It defines your headroom. I can't believe you can disagree with that simple fact with a straight face.

Look at the CSS SDX-15 sealed pair, single REXXX sealed and single LMS-18 sealed. 80-83dB @ 20 Hz 1W/1M. The B&C21 is 73dB and, that's using a pair of them. Subtract -3dB for a single 21" driver. 10-13dB less sensitive is irrelevant???

Sensitivity @ 20 Hz doesn't change just because you cut the top end to affect a lower F3.

Shrink the box to control excursion and add +3dB of amplifier... yes. But, add +10dB of amplifier? Even if you could do that, you don't have the displacement. So, back to adding drivers to increase sensitivity and displacement <20 Hz. When you're talking about 18" and 21" drivers @ a grand a pop, it's just absolute lunacy to even consider.


Quote:


I don't feel the need to go over the GP testing again. Not everything is about HT bass in domestic settings. That is only one possible "job" among many.

YMMV, FWIW, etc...

You don't have to go over anything. Many of us did that exhaustively long before you got interested in the subject, and to be perfectly honest, it's disappointing to hear you say that as though I'm so new to GP testing that you would have to go over it again or explain what possible "jobs" it might relate to.

Yeah, for those who haven't paid much attention, it is definitely all about HT bass in domestic settings for me.

I have to ask, if not for HT, what other purpose would involve cutting the top end of sealed subs with pro sound drivers???

Bosso
post #242 of 535
Quote:
Originally Posted by LTD02 View Post

"A HPF defeats the purpose of using a sealed alignment in the first place."

'not is running one at 10hz iirc.

not is running his system at reference level with the SW trim @ +15dB hot.

There is a LOT of difference in a HPF at 10 Hz vs at 20 Hz.

not's system could be run anechoic flat to 10 Hz with no HPF at reference level in most every HT on earth.

Finally, what not does does not define anything beyond what not prefers to do.

Bosso

Quote:
Originally Posted by FOH View Post

Absolutely, ... individuals utilizing non-standard graphing practices that obfuscate performance issues, and claim otherwise, are delusional. Oftentimes, the one's I've seen such as you describe, know no better.

I thought you were claiming certain software had inherent graphing issues. A bit slow on the uptake, I am

Technically, I was claiming that. The insanely stretched graph is an issue for me. Also, the 6 data point graphing choice adds to the problem, IMHO. If I never ran a measurement in my life, bought OM and ran a sweep, I'd probably think I was stylin' and needed no tweaking whatsoever. In fact, that was the gist of the 3 posted OM graphs... that all you have to do is stick your sub in a room and run Audyssey and there you go. Not a good trend to worship GP results and ignore in room performance, aided by a grossly biased graph and 'auto' EQ, and that's all I was trying to point out.

Bosso
post #243 of 535
Quote:
Originally Posted by omegaslast View Post

^^^
didnt bosso put new drivers and crossovers an basically just use the cabinets in his rocket series?

Yes, I re-did everything and bi-amp using an active analog X-over. Not the highest SQ on earth but then I don't go around from forum to forum telling anyone what mains and CC they should have and why.

DS-21 is just desperately trying to show that everyone (but, really himself) is intelligent and has good sound and I'm not and don't.

It happens. He doesn't have much to say about SSD-18 (morphed to Q-18/X-con-18) group buy, but whaddaya gonna do?

Bosso
post #244 of 535
Quote:
Originally Posted by omegaslast View Post

^^^
didnt bosso put new drivers and crossovers an basically just use the cabinets in his rocket series?

I was not aware of that until your post. His website says "modded," but nothing beyond that.

Following Scott's link, I found the following text (the pictures didn't show up), with emphasis added:

Quote:
Originally Posted by bossobass View Post

***Having recently put new drivers and a stock 2-way passive X-over in my Rocket CC,*** I also decided to bi-amp. I already had a Rane AC23-B active crossover***

One would assume his new Peerless drivers are a good bit better than the cheap ones MLS spec'd, but they're still pint-sized. While I couldn't see the tweeter, even if I could I have no comment because I've never to my knowledge heard one of Selenium's drivers. (I'm sure I have in some PA system at some point, but was never aware of it.)

But regardless, except for lack of efficiency and dynamic capability because of the the size of the drivers, the more salient point is he apparent lack of attention/interest in optimizing the crossover. Odd for someone who preaches to others about accuracy, no?

I guess "accuracy" only matters at 4 Hz

So given that the "modded" speakers use a "stock crossover" (whatever that means) for the center, and a primitive analog active unit that can only do fixed 4th order slopes, delay, and levels (no frequency contouring within the passband) for the other two mains...I see no need to modify my initial comments. They still stand just fine, despite the new information.

Quote:
Originally Posted by bossobass View Post

My limit for boost is +10dB.

Your problem here is that you're unable to make the intellectual bridge between "tools available" and "desired performance," and persist in only seeing a few of the many tools available.

One can flatten response with many ways besides just boost, even with the primitive analog stuff you prefer. (Seriously, those mains cry out for a miniDSP!) Such as creative use of crossover filters. And then one has the benefit of both flat FR to the desired cutoff and high efficiency at the top of the bass unit's passband.

Quote:
Originally Posted by bossobass View Post

OTOH, if you cut a subs top end to get the required response, your headroom is at 20 Hz, not 100 Hz.

Some of us see that as long as a unit is capable of delivering the desired output across its bandwidth, a more efficient driver (that is to say, a driver that sheds less of the amplifier's input as heat) in the upper bass is only beneficial.

No, with such a system design one won't reach the same SPL at 100Hz with a 1kW amp that one would on an unfiltered system.

Let's do a thought experiment.

Take a multisub system with primary subwoofer using dual-opposed B&C 21SW152's in an 150L box, powered by an amp capable of 4kW. Two kW per driver is, for the record, under the manufacturer's stated power handling.

On paper, that sub powered by that amp can do on paper 110dB from 16Hz up. It has, however, an F3 of 96Hz.

Now, what would happen if one puts a 12dB/oct low-pass filter on the sub at 20Hz? The frequency response would change dramatically, right? Assuming no room modes, it would now have an F3 of 20Hz and gently slope down (downward-sloping rather than flat because of the low Q of the system) to ~100Hz. From 100Hz, it would fall off at 12dB/oct. (One can extend the response up top a bit with another filter, if desired.)

Yes, that dramatically affects how much power the driver can pull from your 6kW amp at 100Hz, because the lowpass cut the voltage input to the amp something in the area of 25dB at 100Hz. So the available power is 25dBW lower. In fact, that "6kW" amp will only be putting out about 20W at 100Hz at cinema reference. But that's not really a problem, because when fed 20W at 100Hz the main sub will still put out a bit under 109dB. (No matter what processing one employs, it'll still take about 20W to get 109dB from the sub at 100Hz. of course.)

In that system, if one wishes to flatten response down another octave (that is, to 10Hz, one can apply boost down low, just like on any other system with that much volume displacement. It just so happens that the amount of boost required here is...your 10dB limit.

Now, in the real world one would probably put that low-pass filter higher, choosing a value to provide the designed extension based on the measured response of the system in the room. (Also, because multiple subwoofers sum basically in-phase in the first-mode region, one will get a further boost down low.) So the numbers above are a worst-case scenario.

The bottom line is, in taking the above-outlined approach, one has drivers that even at high levels just aren't shedding much heat, and amplifiers that are going to run very cool and consume very little power because they are barely used, except when a short burst of ULF energy is in the program material. So everything stays cool and happy from a thermal perspective, essentially eliminating dynamic compression in the subwoofer system throughout its bandwidth even if one plays it all day at cinema reference. Likewise, the amps will likely be able to handle those transient loud LF sounds from their reserves, so won't tax one's electrical system unduly.

By contrast, if one uses a super-heavy driver designed for as low an F3 in a given box size as possible, the amp will have to work a whole lot harder over its whole bandwidth, increasing one's electrical bills, and in systems that don't put the subs on a dedicated circuit - which is to say, most systems - decreasing the power available to the rest of the system. Likewise, the driver motor structure will have to deal with much more heat, leading to dynamic compression sooner rather than later.

Quote:
Originally Posted by bossobass View Post

[b]Sensitivity (and displacement) @ 20 Hz is not moot, it's everything.

If you actually believed that, you would not use small closed boxes, but very large boxes. Because in the deep bass the box size basically determines the system's efficiency.
post #245 of 535
Quote:
Originally Posted by DS-21 View Post

I was not aware of that

There, I edited for you. The rest is so wrong, there's nothing there worth a comment.

Bosso
post #246 of 535
Quote:
Originally Posted by bossobass View Post

There, I edited for you. The rest is so wrong, there's nothing there worth a comment.

Bosso

How can one be so clueless as to not understand basic physics, such as the fact that box volume determines efficiency in the deep bass, and yet be so snide?

If you see an error in my math or something like that, please point it out. It is certainly possible that one exists. But your response just sounds like nothing so much as a bully whining after getting a taste of his own medicine.
post #247 of 535
She's gonna blow!!! Everyone take cover in the bunker!! I'm bringing beer and boggle!!
post #248 of 535
Are these still available for group purchase?
post #249 of 535
"I have to ask, if not for HT, what other purpose would involve cutting the top end of sealed subs with pro sound drivers???"

the increased sensitivity lowers the current through the driver which lowers distortion and power compression. there are several ways to deal with this issue. one, as employed by john j. is to lower inductance. an alternative is to use high sensitivity drivers, as this reduces current and its interaction with the bl field.

another aspect to consider is the resonant frequency location. for the higher sensitivity drivers it tends to be located in the upper bass region. around the resonant frequency, the impedance spikes and in turn the current through the driver is very low, frequently 5-10% or so vs. the minimum impedance. this has the same effect as using a high sensitivity driver or one with very low inductance, it minimizes the interaction with the bl field.
post #250 of 535
Quote:
Originally Posted by Jerry Parker View Post

Are these still available for group purchase?

Yes I think at the end of the day the hope is for a group buy still . This train sadly has been derailed significantly. I am waiting on my Xcons to arrive to give to Ricci (along with SSD) to play with and report back. Stay tuned to see how they do and I'd a new thread will get created for them.
post #251 of 535
Sorry to anyone who is actually wondering about the SSD, Xcon or Q drivers.






Quote:
Originally Posted by bossobass View Post

I agree, and have said basically the exact same thing, except the "sensitivity there is moot" part (see below).

My limit for boost is +10dB. Looking at 'most' rooms, PVG doesn't kick in until around or just below 30 Hz. That means you need to be flat to that point anechoic. So, my limit for roll off at 20 Hz is right at -15dB. If you choose to cut the top end in the case of a driver like the B&C (or JBL or whatever), you look at displacement. The top end you cut is not headroom, it's tossed in the waste basket.

As far as sealed systems are concerned F3 alone is not a big issue as far as I am concerned. I don't have a strict limit for boost or cut or roll off. I care about available headroom, efficiency and displacement much more. I'm also hesitant to categorize too much as typical of a typical room. The variance in size, shape, construction and placement of the subs and listening position cause too much variance IMO. Either the system will have the headroom available to support the signal manipulation and playback levels desired or not.

You say that the extra top end headroom is wasted. It may not be used often but I consider that a good thing not bad. It is always there as potential that could be used and will lower energy use and stress on the amp. You can say that it is wasted potential. I consider it possibility or insurance and extra potential output headroom anywhere a good thing.


Quote:
Originally Posted by bossobass View Post

If you watch a movie at reference level and your system operates cleanly across the board at that level, then essentially, use an all pass filter to 'cut' the entire systems BW by lowering the MVL to -10, how do you have headroom? You have headroom in the sense that you can safely bump the MVL by +10dB if you choose to.

OTOH, if you cut a subs top end to get the required response, your headroom is at 20 Hz, not 100 Hz. You don't have the same option as in the illustration of the entire system. When the driver or the amplifier bottoms at 20 Hz, there is your headroom ceiling. If you attempt to utilize the 'headroom' at 100 Hz by bumping the SW trim or MVL, you'll exceed maximum capability <20 Hz.

The headroom equals out the same either way whether you boost or cut. It doesn't change the max power from the amplifier or the mechanical limits of the driver.

The first paragraph is something we all agree on. Go overkill. Make sure that you have the headroom to reproduce any level that you might potentially need over the bandwidth you want. Reduce the level by 10-15dB and that is where we all want to be with a system that is coasting and operating in a linear, untaxed fashion. Now what that has to do with the driver type discussion I don't know.

As to the second paragraph, it goes both ways. Sure it is more typical to run out of headroom in the deep bass due to displacement issues, I think we can agree there, but every system has an eventual output ceiling everywhere, not just at 20Hz.

[quote=bossobass;21500313]Sensitivity (and displacement) @ 20 Hz is not moot, it's everything. It defines your headroom. I can't believe you can disagree with that simple fact with a straight face.

Straight faced here...20Hz sensitivity in a sealed box is 95% airspace available and about 5% driver. You can go through an entire library of 15-21" sub drivers that you have TS specs for and the sensitivity at 20Hz won't vary by much more than 2dB. Sure you can always find an outlier or 2 but even in that case you will be lucky to find a 3dB difference. That is not enough to worry about especially when these systems are almost always displacement not power limited at those frequencies.

Quote:
Originally Posted by bossobass View Post

Look at the CSS SDX-15 sealed pair, single REXXX sealed and single LMS-18 sealed. 80-83dB @ 20 Hz 1W/1M. The B&C21 is 73dB and, that's using a pair of them. Subtract -3dB for a single 21" driver. 10-13dB less sensitive is irrelevant???

This is a flawed comparison. The XXX is in a 9 cu ft enclosure. The SDX's are in 8cu ft. Those airspaces alone give a large boost. The LMS is in about 4ft. The original 21 dual opposed was not compensated for at all and it loses a ton of apparent output at 1m because of it. I have learned a lot since then and realized that I was not doing some things in the best manner at first, not to mention there were equipment limitations. That is why all of those old tests are being completely re done to get back to parity between everything even though it is a ton of work.

Here is the 100w/10m sensitivity, for both the LMS Ultra in about 3.5cu ft and the dual opposed 21's in a about 5.8 cu ft for both, with 1/3rd octave smoothing applied to make the graphs legible. These enclosure volumes are my best estimate. I subtracted 3dB from the dual 21's to show what the 1w sensitivity of a single in <3cu ft should be. The LMS driver has slightly more volume which will help the low end a bit. Also the voltage input to the 2 cabs is what is calculated as being 1w or 100w for 10m into the DCR but it is rounded to the nearest 10th, etc. All I'm saying is that there is some fudge in there still either way. Can't really help it.

Attachment 234349


The LMS shows what amounts to a little over 2dB better sensitivity at 20Hz. Not exactly a huge amount and it has more enclosure volume. Also there is still the fact that the 21 system was dual opposed which may still have some effect at 10m. I will need to get the single 21 sealed measured to know for sure on that front.

Quote:
Originally Posted by bossobass View Post

Sensitivity @ 20 Hz doesn't change just because you cut the top end to affect a lower F3.


Nobody ever said that it does. You were the one making it seem as if there is a major sensitivity difference at 20Hz which there usually is not. It is overwhelmingly controlled by the airspace available. If you alllow one driver 3x the airspace, of course it will have a large advantage. If the airspace available is kept constant, at 3 cu ft for example, the difference in sensitivity will usually be 3dB or less. Not an advantage worth stressing over.

Actual efficiency is a whole other matter.

Quote:
Originally Posted by bossobass View Post

Shrink the box to control excursion and add +3dB of amplifier... yes. But, add +10dB of amplifier? Even if you could do that, you don't have the displacement. So, back to adding drivers to increase sensitivity and displacement <20 Hz. When you're talking about 18" and 21" drivers @ a grand a pop, it's just absolute lunacy to even consider..


There is no need for any different of an amplifier. The sensitivity difference is <3dB. Broken record here...Displacement is THE consideration for low bass output. Sensitivity is barely on the radar for small sealed systems as the box volume sets it. If and I mean IF you can get a pro driver with enough displacement to do the low range justice and with freedom from mechanical noise then yes it will offer some advantages over a heavy mass driver that has similar displacement but much less efficiency. Whether these types of drivers exist or not? I don't know.


Quote:
Originally Posted by bossobass View Post

You don't have to go over anything. Many of us did that exhaustively long before you got interested in the subject, and to be perfectly honest, it's disappointing to hear you say that as though I'm so new to GP testing that you would have to go over it again or explain what possible "jobs" it might relate to.

Yeah, for those who haven't paid much attention, it is definitely all about HT bass in domestic settings for me.

I have to ask, if not for HT, what other purpose would involve cutting the top end of sealed subs with pro sound drivers???

Bosso

And I find it disappointing that you make remarks about how GP testing is pretty much worthless all of the time, but next thing you know you seem to use it in a lot of your posts to defend your position or attack others. We can't even get enough information from manufacturers to know what the many hundred dollar drivers that are being bought actual response shape is. All people have to go on is logic and subjective user info for the most part when making a choice about what to buy, or maybe some simulation that's about as close to accurate as some manufacturer's marketing claims. That is what people spend thousands of dollars based on. It seems pretty useful to me to have some objective information available about how a component that I am considering for use performs.

Other jobs for sub drivers? Mobile, marine, fixed venue install, musical instrument, portable PA, commercial cinema, HT, outdoor, 2ch music only.

I have never once suggested that anyone use these or any other pro drivers in the manner you seem to be suggesting that I or someone else did. Sure I will investigate it for myself because...why the hell not?, but I haven't even came to my own conclusion on those particular drivers suitability for it yet. I am not the one that derailed this thread with talk of it either! This thread is about the Fi made drivers for the love of Pete.

This whole discission boils down to is there a large sensitivity difference below 30Hz? The answer is no. Therefore the amplifier and power requirements stay close enough to the same.

Item #2. Do high efficiency drivers have enough displacement, robustness and and freedom from noise to be viable for <20Hz playback. In most cases no. In a few cases possibly. Are any of them $$$ for displacement leaders? Hell no.
post #252 of 535
tgse3, why did you choose xcons? vs. say zcons or the fi q's?
post #253 of 535
Quote:
Originally Posted by Ricci View Post



And I find it disappointing that you make remarks about how GP testing is pretty much worthless all of the time, but next thing you know you seem to use it in a lot of your posts to defend your position or attack others. We can't even get enough information from manufacturers to know what the many hundred dollar drivers that are being bought actual response shape is. All people have to go on is logic and subjective user info for the most part when making a choice about what to buy, or maybe some simulation that's about as close to accurate as some manufacturer's marketing claims. That is what people spend thousands of dollars based on. It seems pretty useful to me to have some objective information available about how a component that I am considering for use performs.

Other jobs for sub drivers? Mobile, marine, fixed venue install, musical instrument, portable PA, commercial cinema, HT, outdoor, 2ch music only.

I have never once suggested that anyone use these or any other pro drivers in the manner you seem to be suggesting that I or someone else did. Sure I will investigate it for myself because...why the hell not?, but I haven't even came to my own conclusion on those particular drivers suitability for it yet. I am not the one that derailed this thread with talk of it either! This thread is about the Fi made drivers for the love of Pete.

I have no idea what you're talking about in the 1st half of your post so I'm just going to let it go and disagree with most everything you said in it. Except that I'll say once for the record, I don't attack anyone. There ain't no statue of you in my church, so if and when you say something that's just not true, expect more than me bowing in front of your measurements.

I build subs and see how they do in rooms. They do pretty flippin' good. No outdoor GP measurement regimen is going to change that. I get plenty of accurate information from manufacturers. GP measurements isn't going to change that. I post my results and talk about how to get there. You apparently think the few available drivers-stuck-in-a-box and powered by whatever amplifier is handy is more valuable. I don't. So, if you voice your opinions on the matter, all is good, but if I do the same, it's attacking?

Lighten up, man. A tiny % of the world even knows there's a such thing as GP tests, let alone claiming to be on some crusade to save the subwoofer buying public from evil manufacturers.

Quote:


This whole discission boils down to is there a large sensitivity difference below 30Hz? The answer is no. Therefore the amplifier and power requirements stay close enough to the same.

Item #2. Do high efficiency drivers have enough displacement, robustness and and freedom from noise to be viable for <20Hz playback. In most cases no. In a few cases possibly. Are any of them $$$ for displacement leaders? Hell no.

Whether or not there is a large sensitivity difference where it counts matters less than the fact that you lose all of your so-called high sensitivity and that that sort of driver will never have higher sensitivity at 20 Hz than one that's designed to be a HT sub.

Your attachment didn't show up for me, but irrelevant. All HT drivers have higher sensitivity than the B&C type drivers @ 20 Hz. Spare the box size lecture, please.

Item #2; on this we are in agreement. I never said you said anything about them being better or worse for anything. There are many other people posting here. You might want to read some of them.

This thread is about whatever the particular person posting says it's about. Fi SSD? Yeah, not so much. Fi Q, SSA XCON, modded MFW-15, ground-up driver X and B&C suspensions along with continual lectures about the superiority of low Q, High Bl, high sensitivity whatever.

Basically, this thread has been held up until you get the Q, XCON and SSD. So, you'll test for self noise by ear and get a rough FR in a box. Do I have it right?

Bosso
post #254 of 535
"I have no idea what you're talking about in the 1st half of your post so I'm just going to let it go and disagree with most everything you said in it."

bosso? that doesn't make much sense...
post #255 of 535
Quote:
Originally Posted by LTD02 View Post

tgse3, why did you choose xcons? vs. say zcons or the fi q's?

Aesthetics, pricing, specs, customer service, to benefit the group buy cause.
It ends up being cheaper or same price to get an Xcon as it does to buy a loaded Q with the added benefit of aesthetics. When I emailed/called around for a group buy Aaron was most prompt with his responses and willingness to help in a group buy. To help people make up their minds I decided to grab a few to have Ricci test out. This way we will have Xcon, SSD, and Q numbers for people to form their own opinions on. Right now I must say I'm pretty happy with my SSD's for the price, but we'll see how they measure out. I'm not sure what I'm going to do with six 18's now though.
post #256 of 535
Quote:
Originally Posted by tgse3 View Post

Aesthetics, pricing, specs, customer service, to benefit the group buy cause.
It ends up being cheaper or same price to get an Xcon as it does to buy a loaded Q with the added benefit of aesthetics. When I emailed/called around for a group buy Aaron was most prompt with his responses and willingness to help in a group buy. To help people make up their minds I decided to grab a few to have Ricci test out. This way we will have Xcon, SSD, and Q numbers for people to form their own opinions on. Right now I must say I'm pretty happy with my SSD's for the price, but we'll see how they measure out. I'm not sure what I'm going to do with six 18's now though.

Werd. I'm still interested in the XCON's but the lack of vent pole is making me go... ehhhh. So far, there really isn't any driver that I really like enough. I miss the Mal-X and my RLp's.
post #257 of 535
Quote:
Originally Posted by Scott Simonian View Post

Werd. I'm still interested in the XCON's but the lack of vent pole is making me go... ehhhh. So far, there really isn't any driver that I really like enough. I miss the Mal-X and my RLp's.

The SSD has no pole vent and thus far I notice no noise coming from it sealed. I'm running 1 per channel on EP4000 in 5cu. Time to do some cardio so I'll pay more attention to them, and see if I notice any noise while I'm down there.
post #258 of 535
Bosso,

The attachment would have shown that an LMS in the same enclosure volume as the 21 results in all of a 2dB advantage in sensitivity at 20Hz or slightly less as confirmed through measurement and simulation. Not enough of an advantage to worry about. The LMS is one of the more sensitive drivers at 20Hz to begin with.

You have posted some points about sensitivity that are incorrect as far as I know which is the reason I commented on them. We can discuss that or not. As you say "when someone posts something that is not true, expect more than me bowing down to your measurements." I reserve the same. Which points am I wrong as you mentioned?

I don't see any reason to make competing, condescending or snide remarks to each other as some of the comments in your last post certainly came across. I think we can have a conversation without the attitude.
post #259 of 535
Quote:
Originally Posted by Ricci View Post

Bosso,

The attachment would have shown that an LMS in the same enclosure volume as the 21 results in all of a 2dB advantage in sensitivity at 20Hz or slightly less as confirmed through measurement and simulation. Not enough of an advantage to worry about. The LMS is one of the more sensitive drivers at 20Hz to begin with.

You have posted some points about sensitivity that are incorrect as far as I know which is the reason I commented on them. We can discuss that or not. As you say "when someone posts something that is not true, expect more than me bowing down to your measurements." I reserve the same. Which points am I wrong as you mentioned?

I don't see any reason to make competing, condescending or snide remarks to each other as some of the comments in your last post certainly came across. I think we can have a conversation without the attitude.

I have to get this out of the way first. I don't intend my posts to be 'snide, condescending', but I suggest you read LTD's and DS-21's comments to me leading up to your "I'm not going to go over GP measurements again" comment.

If you guys can't take it, don't dish it out. The best tact (with me) is to not be cryptic with no data and too much "you're the dumb guy, we all know better" insinuations. Life's too short and I have little tolerance for that nonsense. Have the stones to spit it out straight away and back it with some actual facts, data, whatever ya got and we can get it over with and move forward.

Next, I generally don't talk out the wrong hole. If I know something to be the facts of the matter, I post it. I used your own posted measurements to make a simple, basic, HT subwoofer driver 101 point.

There is all of this recent BS about high sensitivity drivers. I call is BS because that's exactly what it is. You do not preserve any headroom when you cut the top end or boost the bottom end. You do not spare the VC from maximum voltage. You do not have better sensitivity.

Headroom is defined by where the sub driver and/or amp bottoms. That's why every commercial sub on earth has limiters, without exception.

95dB drivers give up sensitivity at 20 Hz because they aren't designed to operate at 20 Hz. Therefore, when the very few of them that have any X-max are asked to hit X-max, they require more voltage, not less.

The B&C is a perfect example. Your measurements show it as the "All Time Minimum Efficiency" sub @ 20 Hz:



And, please don't go into the "LMS in the same box..." stuff. It doesn't change the fact that these drivers don't have the displacement and need more power to get it out of them.

No, I won't be surprised at what the B&C 21s will do. It's math; SPL = 112 + 10 * log(4 * pi^3 * Ro / c * (num * Vd)^2 * f^4). They may give less than the math dictates because of a bogus X-max spec, Sd spec or non-linear behavior, but they won't give more. The box size won't matter. The amplifier won't matter. The method of signal shaping won't matter.

This stuff, as I said, is purely basic HT subs 101. You can up the sensitivity by putting the driver in one of the resonant systems (which is what low Q drivers are designed for), but there are tradeoffs in doing that. Just like the high sensitivity # for a subwoofer driver; gain it here, lose it there.

Yes, you may model extreme examples of each driver in extreme examples of boxes with extreme examples of signal shaping methods, but, although you may close the gap somewhat, you will not change what I just posted.

My shop is pretty much closed on this issue. I've tried to debate it with data and facts, but after the whole "everyone else knows..." baloney, backed by nothing, I'm just not interested in going on and on. Build what you want, buy what you want, believe what you want. I've said my piece, so others can use the search function if they really care.

Fact is, Tumult, Mael-X, SDX, Sound Splinter, Blueprint and every HT driver vendor are gone. Kyle Richardson, Scott Atwell, Dan Wiggins, Kevin Haskins, Brian Bunge, John Janowitz, et, al... all gone. The market is simply too small to make a profit and the loud calls for 18" and then 21" drivers shrank the market further still. Brian Ding is the last man standing and I personally believe that's because he stayed conservative with a 15" driver size limit.

The next best option is the so-called 'car driver'. I usually do not recommend drivers/boxes/amps to anyone, even though I get requests for such every week. I talk about what I build and why. I don't care what anyone else does or why they do it. But, I decided to recommend the Fi stuff to a few people in PM. Several have ordered and received them. I built a pile of subs and loaded a couple of systems with the SSD-15s. I found them to be good quality, relatively inexpensive (the SSDs with the pole vent were $199) and packed a lot of firepower in a small space.

There is the HT sub, the car sub and the pro sound sub. Absent a good HT sub, the car sub is the next best logical choice. That's what this thread is supposed to be about, not what 'everyone else knows' about pro sound stuff or what center channel I use.

If the SSD GB (what this thread is supposed to be about) turns into the Q GB, I'm still interested, if Scott cares to offer a discount or answer the e-mail request at all. For the record, I won't buy anything from the Aaron guy and I feel that those who feel differently should have started or should immediately start a new thread.

Bosso
post #260 of 535
wow, some serious reading to catch back up on this thread. Ricci, did you manage to make any more headway with the "Q" this past long weekend??
post #261 of 535
Bosso,

I did post some refuting information a couple of posts back. I'm not sure what happened to the link, but as I explained the original data which you are using for your point for the dual 21 opposed is not compensated at all and as such is misrepresentative. Ever since I tested the Empire I knew it would be way off. I commented on it being way, way off from the simulations back when it was originally posted and there is a disclaimer on the results as not being up to the current standards I'm trying to hold myself to. I should have pulled it down truthfully. I have re-done measurements with the current LMS and the dual 21 but have not had time to update the site yet. I have lowered the 21's by 3dB in order to show what it should be with 1 driver in <3 cu ft. Again this still isn't a true apples/ apples comparison, I need to test a single 21 forward firing in the test box I have made up, so there could be another+/-1dB either way on this but it should be close.

Attachment 234416

Here is a very simple simulation of the 1w spl of the LMS, 21SW152 and an SSD18 D2 all in a 4cu ft sealed enclosure. Below 30Hz the LMS is the most sensitive by almost 2dB over the others. The SSD and 21 are almost identical.

Attachment 234417

I don't consider this a large sensitivity advantage down low. What you have posted about the high efficiency drivers versus low efficiency ones does not always hold true. With similar driver SD in similar enclosure volume you will not see much more than a 3dB sensitivity difference in practice at 20Hz unless one of the drivers has a huge amount of inductance affecting the response which will lower the sensitivity.

What you will see is that the actual power delivered by the amp can vary quite a bit due to the impedance. Higher impedance indicates less current and power needed indicating an easier load on the amp. In other words efficiency. This is a more important thing to look at than sensitivity alone. The system resonance plays a huge role in where the efficiency occurs at. If true higher efficiency is wanted down low you will need to lower this as much as possible, but it will sacrifice efficiency up top or vice versa. No free lunch. Also motor force plays a role here as well.

Below is the same simple simulation of the LMS, 21, and SSD in a 4cu ft box but instead we show the current or power actually being used. Again we see that the LMS is by far the most efficient down low on top of being more sensitive, due to it's low resonance and very strong motor. The 21 with it's much higher resonance and strong motor is most efficient by far up top but requires more power down low until about 10Hz where it eventually comes to parity with the LMS. It is still slightly less sensitive in that range still though. The SSD actually requires more power basically everywhere and has lower overall sensitivity so it is obviously the least efficient and will place more demands on the amplifier to reach the same output levels in the deep bass.

Attachment 234418

I get lot's of PM's asking for advice too. I have never recommended that someone place a pro style driver in a small sealed enclosure and L/t it to anyone. That should say plenty about my thoughts on it really. The only issue I take is with the blanket statement that high efficiency drivers are always less sensitive or efficient down low. That is not always the case. The FR is obviously highly tilted which does pose some questions or challenges of how much manipulation one wants to use. The real big issue with the pro style driver, which we agree on, is the lack of displacement and freedom from mechanical noise at high excursion. The best attempt that I have found is the 21sw152 and it is a $750 driver which offers the total displacement of a moderate xmax 18".

Let's move on to the Fi drivers.
LL
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post #262 of 535
Quote:
Originally Posted by Ricci View Post

Below is the same simple simulation of the LMS, 21, and SSD in a 4cu ft box but instead we show the current or power actually being used. Again we see that the LMS is by far the most efficient down low on top of being more sensitive, due to it's low resonance and very strong motor. The 21 with it's much higher resonance and strong motor is most efficient by far up top but requires more power down low until about 10Hz where it eventually comes to parity with the LMS. It is still slightly less sensitive in that range still though. The SSD actually requires more power basically everywhere and has lower overall sensitivity so it is obviously the least efficient and will place more demands on the amplifier to reach the same output levels in the deep bass.

Attachment 234418

I pay very close attention to this stuff right here when I sim subs anymore.
post #263 of 535
The problem I see with the arguments come from not talking about the same comparisons. My best guess is that Bosso is primarily considering drivers in the box volume that gives the type of excursion protection he wants, which will be a Qb of 0.65-0.8. For some very stiff or strong motor drivers this will make for very small boxes.

Ricci and a few others were commenting that if you don't worry about the exact Qb of the sealed box (within reason), then for a given box size (assuming not overly huge relative to the driver parameters) the low frequency SPL output per watt input will be very close. How much the response rises above 20Hz will vary with driver parameters, and how close the sensitivity is below 20Hz will depend on how soft or stiff the suspension is. Unless drivers are way too stiff for the application, you will often only see 2-3dB differences, with another dB possible due to different DCR values to fudge the real vs. nominal power input.

The smaller the box, the less the suspension will matter, while larger boxes make bigger differences. What is really going on is that the driver's suspension + box compliance (volume) set a maximum efficiency. A very stiff suspension is the same as a smaller box on the same motor and mass parameters. This is why IB woofers are more efficient down low with soft suspensions, as the driver's suspension is what determines the equivalent of the sealed box size.

Other than bosso setting some limits on the max response deviation he prefers above 20-30Hz, I think many are arguing the similar ideas from different angles.

My only addition would be that while 2-3dB is not a huge difference in maximum output and excursion requirements, that makes for a reduction in required power per SPL by 35-50%. Remembering that real power usage means that you will almost always be producing power higher in frequency when you tickle the max excursion limits, that 2-3dB can be a tangible and useful difference in max output and reducing current related compression and distortion, not to mention increasing the amplification options at lower power.
post #264 of 535
Ok. I free air'd the Q for a while at pretty generous levels over the weekend and also put it in my old 4cu ft sealed enclosure and ran it for a while.

There is some air noise from the motor at high excursion but truthfully it doesn't seem to be much worse than other high xmax drivers. There is quite a pile of air jetting through the frame ports but it doesn't seem to be excessive at 2 or 3" of excursion. On that front it seems to be fine. Especially once it is buried inside of an enclosure it should be a non issue. However what is audible is a tapping sound that develops somewhere between 1" and 1.5" p2p. I thought it was the leads at first but they have felt on the bottom of the cone above the leads and the didn't apear to be hitting especially at that moderate drive level. Perhaps it is the spiders, excess glue somewhere or even rocking? I am not sure. It doesn't seem to get any worse at higher drive levels or develop into a very loud tap or knock. It is audible with the sub mounted in the enclosure. I had hoped that it would work itself out as these things sometimes do. Other than that the driver seems to operate without a lot of suspension noise until past 2" p2p. It is robust and I believe that I took it to between 2.5" to 3" p2p a couple of times and though it was noisey and obviously distorted at that level it didn't seem to be in any danger mechanically. I believe the Fi drivers are spider limited and you will have to break the triple joint before it will hard bottom. The foam surround is huge and seems to do a very good job as I didn't notice any obvious deformation even during the highest excursions. Seems really robust. I did smell some coil glue during this so the newness has been knocked off. (That is typical for new drivers getting heated up for the first time).

After all of that I did get another set of measurements of the impedance and specs. They changed quite a bit. FS dropped notably from the suspension loosening up. This is the biggest change I have ever seen on a driver. It was definitely new when i recieved it. It smelled like a gas station when I recieved it. since the parameters changed so much I am going to keep running it for a while longer and test it one more time to see if they shift even more.


Attachment 234428

Attachment 234426



I have also included a simulation using the specs generated. One is a simple simulation like you would see using winisd without inductance. The orange trace is a more detailed simulation like what you would see using winisd with simple inductance. The third yellow trace is with complex impedance curve fitting and frequency dependent inductance modeled in. WinIsd will not do this. (BTW Mark I did finally remember that the WT2 has a simulator built into it that will do this. Unfortunately it is not free or that intuitive to use really.)


Attachment 234427



Attachment 234437



It looks very peaky. Not what I was hoping for really. This measurement is far from ideal and it may accentuate the peak due to being an extreme close mic that is in room. The actual response might flatten out some when properly tested outdoors but that hump will still be there. However the close matching of the simulation response has me doubtful that it will improve much.
LL
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post #265 of 535
Josh, Unibox has a feature for complex inductance modelling (that I just recently figured out how to use. ) and your new models jive with some of my predictions in Uni. Pretty much ALL of these recently discussed drivers...dare I call them 'car subs' (lol!)... have very peaky response. Some worse than others.

Lemme plug in your brand new numbers and see why I get. Brb.
post #266 of 535
Quote:
Originally Posted by Scott Simonian View Post

Pretty much ALL of these recently discussed drivers...dare I call them 'car subs' (lol!)... have very peaky response. Some worse than others.

I assume that's not a good thing for home theater use correct??
post #267 of 535
Quote:
Originally Posted by edoggrc51 View Post

I assume that's not a good thing for home theater use correct??

Well... ummm... not necessarily. Just means they're 'peaky'.

More EQ needed, less of a naturally smooth response but this isn't exactly abnormal either.


Back with Unibox results. Please bare in mind that these are numbers ripped straight from Ricci's last post before mine with the numbers he extracted from a 'new yet burned in' unit. These numbers are still subject to change over time, I believe and some margin of error must be considered.

That being said, my numbers aren't too far off.

Sims are in a 4cuft sealed box with 1,500w applied:










Discuss.

post #268 of 535
So in general are you saying perhaps more EQing is needed out of this guy, or its too far gone to pull back? have your run any content through to see how it sounds doing stuff other than sine waves or sweeps?
post #269 of 535
Quote:
Originally Posted by Scott Simonian View Post

Josh, Unibox has a feature for complex inductance modelling (that I just recently figured out how to use. ) .

REheeheeheeheeheEEEAAAHHHLLLY....

I haven't touched Unibox in years. Time to dust it off. Actually that is awesome becuse I didn't think it had this capability. Now the only problem is manuf's don't give this info.

If you look at the measured model compared to one without the frequency dependent LE factored in it is a HUGE difference. Sensitivity goes way down.
post #270 of 535
Yup. Made most drivers I model look pretty ugly save for: Aurasound, Dayton RSShf, and anything AE.

What do you think of the sim'd results?
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