Stereo Integrity's new HT Subwoofer - Page 3

Dave,

We have been over this many times back and forth. We both have our viewpoints and opinions on this inductance thing. Data-Bass driver and DIY tests are about gathering info on how the drivers compare to each other and how different system alignments compare to each other so that the data can be useful for making decisions about what approaches to take depending on the application. Sealed enclosures are used for comparing drivers because it is the simplest, easiest to understand comparison to make. I'm looking at the performance of components to figure out how they might react in various possible scenarios, while you are always talking about the final system, small sealed, 80Hz low pass and a medium/small HT room, a very specific use and app. While it does take some forethought to implement a full bandwidth HT bass system like you have done and I think everyone here agrees your system performs well and also looks great in the process, it is not exactly difficult to accomplish as you have said yourself many times. A high inductance driver is certainly not a deal killer either and we agree there.

My view is if I am starting from scratch and choosing a driver the lower inductance driver is usually a better all around performer for all of the reasons I listed earlier. Why not pick it from the get go if it is available? I don't see the problem here? It's like you view a low inductance driver as a negative or something. You seem to be of the view that inductance does not matter, distortion does not matter, response shape does not matter, sensitivity and efficiency does not matter and thermal compression does not matter at all. EQ and massive firepower will fix all of this in the end. What does this leave to base your driver decision on? Displacement and cost is just about all that is left on the table. Is this your stance that when choosing drivers for bass all that need be looked at is displacement (which would really be xmech and not xmax since we don't care about distortion) and cost? Perhaps with a side of long term availability speculation? Massive headroom does take care of many of those issues but if I am starting from scratch and have a choice of $250 20mm xmax driver A with a huge peak in response due to inductance and 20mm xmax driver B at $250 with a much flatter response shape and some inductance measures, I'm going with B because it will likely be the better all around driver regardless of whether we will ever hear a difference because are using so many of them with so much power that they will never operate at even 35%. What about all of the other possible applications? I agree with LTD02 when he says there is a reason that all of those engineers at these transducer companies put effort into it.

You mentioned the SSD which is about $300 after shipping and about $340 with options so we will use it to rep the higher inductance drivers. Here are a few comparisons with the UXL. Obviously the UXL is a more expensive driver about $550 after shipping. It still exhibits inductance roll off but there is a very large difference between the shape of its curve which is 3.5dB down at 100Hz and about 5dB at 200Hz and exhibits a very mild hump versus a lot of these other drivers which are down 7-10dB by 100Hz and 12dB by 200Hz while also exhibiting a sharper roll off towards 20Hz as well. There is a dramatic difference between the two response shapes IMHO. Not to mention the large sensitivity differences.



This shows that the differences in response translate at higher output as well. The SSD is compressing much more and never makes up that ground being about 5dB down at 10Hz and about 4dB less output over a large percentage of both the upper and lower bandwidth.



I don't have the THD sweeps for the UXL but here they are for the SSD. Distortion is really high everywhere than at the response peak at system Fb. Especially in the low bass and upper bass. As a trend the higher inductance drivers seem to have higher distortion and less output. I could actually hear the second harmonic distortion out of this driver during the last 3 sweep levels as in the deep bass it sounded like the sweeps doubled back on themselves and repeated instead of steadily increasing.



The SSD could not produce 100dB at 20Hz with less than 30% THD. The higher inductance drivers again seem to show a trend where they have reduced output and much higher distortion the further away from system Fb and the response peak they are. They do not respond as linearly to frequencies outside of that narrow band.

dave, many companies that have a great deal more experience engineering subwoofers than you do go to considerable lengths in order to linearize and or minimize inductance in subwoofers.

this makes their subwoofers more complicated to manufacture and more expensive in the marketplace. my argument is simply that they would not go through all the trouble if it had no effect on the sound.

as for measurements, the effect can be measured using the klippel method for le(x), which is inductance as a function of the position of the coil. the drivers that have good inductance control will have a relatively constant or flat line, while the drivers that don't will have a non-uniform inductance or a sloped line.

...
Edited by bossobass - 10/19/12 at 7:05pm

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Edited by bossobass - 10/19/12 at 7:06pm

"Still, my offer to LTD stands. We won't be playing progressive sine sweeps and I'll have 8 of them. And, I'll bet my dirty socks he'll prefer the THD."

dirty socks? what are you talking about now? here is the w15gti which employs good inductance management. it is not a pro audio driver.



you also left out the av15h from ae (unavailable), the new alpine swr d4, the re xxx18...none are pro audio drivers, but all employ inductance management in one form or another.

"Actually, I like that UXL driver."

it is a good one, but limited on the inductance front. hence the r&d on the lle. ;-)
Edited by LTD02 - 10/18/12 at 7:20pm

He didn't forget about it. He pointed out more than once how it is out displaced by the Tumult and therefore inferior in my thread.

displacement is a different topic. the subject at debate is the extent to which inductance control matters in subwoofers.
Edited by LTD02 - 10/18/12 at 8:00pm

Not really. That seems to be Bosso's preferred performance metric for drivers. Clearly it's not Le.

Quick story...

Early last year I was sent a commercial subwoofer to test and review. Quickly I realized that there were some "issues" with this product. The largest one was the drivers inductance. The response shape looked like what you see in many of the drivers tested at DB just a big 10dB peak at 50Hz and very sharp roll off to either end. It looked terrible and this was a "finished" product. Additionally the distortion was really high even at moderate levels and the maximum output available was dreadful everywhere except at the response peak. EQ would not have fixed this. I contacted the company back and gave them my recommendations of what to do with the sub including item #1 being improve the driver and get some shorting paths in that motor. We decided to abort the review and they went to work improving the product. Months later a version 2 with an improved driver came back. This driver looks exactly the same as the first version and uses all the same components as before except for 3 pieces. The only changes made were to the T-pole where a copper pole sleeve was added and the magnets had a moderate diameter increase in order to offset the decrease in force. None of the suspension or cone components were changed and the xmax and xmech were physically the same as well. I was told that the total cost increase per driver amounted to about $20 each. The amplifier and cabinet were the same as before.

The FR went from +/-3dB 37-63Hz (Seriously) to +/-3dB 25-125Hz. This same shape was maintained during the maximum sweep levels for both. With CEA-2010 testing the new system with the low inductance driver gained an average of 3.5dB over the old system averaged across all 1/3rd octave centers recorded. Additionally distortion dropped and where the old system would not even produce a passing output in 2 bands the new one did on top of being a little louder at the same time. Everywhere away from the peak in the old system the new one recorded an increase in output of 4dB or more. Right at the peak and near it the old model had a slight edge in peak output. It got trounced everywhere else across the whole bandwidth. THD in the upper bass and lower range dropped noticeably as well.

The majority of this was caused by adding a copper pole sleeve to the driver motor which otherwise was basically unchanged. Audio memory is bad but i have no doubts that the second version product is vastly superior to the old one and sounds it. It's not about types of driver or application specific or any of that. Bass drivers without steps taken in the motor to linearize and lower inductance are not as good as they could be or drivers that have those steps taken during the design.

I just came across this thread form a mention somewhere else. The subwoofers are real and are not vaporware. They are being produced as I type this. Production should be finished in about 30 days at which point they will be shipped to our facility.

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Edited by bossobass - 10/19/12 at 7:06pm

;';;
Edited by bossobass - 10/19/12 at 7:07pm

I think it's high time for the few of you with the personal axes to grind to do so in private. SI's thread has been virtually destroyed by this nonsense, which isn't fair to Nick. Move along please.

i have long wondered why copper sleeved poles seem to cost so much more. never could reconcile it with the relatively low price of copper (few bucks per pound) and what seems like a relatively simple mechanical addition.

interesting.

"Yep, this is the problem. Here we are a dozen years and a couple million posts into it and the basic fundamentals are questioned as though debatable."

seems like the extent to which low/linear inductance matters in subs is debatable, hence the debate. :-)

Cool story! No...seriously.


I am awaiting for your product to be in stock. Then they will be real for the rest of us mere mortals.


Chill out. No thread is being destroyed. This is all appropriete discussion. There is nothing else to talk about until poeple actually get the drivers and use them.

Snuck around Data-Bass looking for new stuff... found some early documenation on the driver itself. So far, this is shaping out to be an outstanding driver. Especially considering the cost.

http://www.data-bass.com/data?page=driver&id=46

This thread has definitely been trashed. It was supposed to be about SI's subwoofers, not a pissing contest between a few people rehashing a previous war. 75% of what's been posted thus far is neither appropriate or germane, because it has nothing to do with the threads intent. If there isn't anything to discuss until the drivers are released then perhaps nothing should be posted until then.

That was a great write-up.

Definitely. If these are going to be as good as they shaping out to be and measure as well as they are modeling then....dayum. I'll be in for a dozen. Tons of bass for cheap. Still, I will not participate in the pre-order. I will wait for them to be in stock. Pending a full review from Josh, of course.

"This thread has definitely been trashed."

i don't see it that way at all. just a few guys with different perspectives kick'n around some thoughts.

if you want to focus on problems, go back to bosso's post (#14) where he points out that the stiching on the 15" sub is all over place. maybe it was just a prototype and the production subs will be fine, but that isn't exactly confidence inspiring.

Exactly.

The floor's all yours Jim. Tell us all about it.

Getting back to the original topic, have any of you guys received your SI subs? I wonder how this SI 18" will compare to one of the new Dayton 18's? The SI 18's are definitely cheaper. I would be interested in knowing how the SI 18, Dayton 18, and the SSD-18, all compare when used in both a sealed enclosure and also a ported enclosure? How many watts would be needed to drive one of these 18's in a sealed enclosure? Would something such as a Dayton 500 watt or Dayton 1000 watt plate amp work to power these in a sealed enclosure? Or would something like a Behringer EP-4000 be needed?

What is the SI HT driver ? A low cost to displacement ratio driver is the best way to describe it. Again... lets remember it's not a $1000 reference driver; it is made to be very affordable and offer respectable (class leading in this case) performance for it's price.

There is way too much attention placed on something as insignificant as surround stitching. Cones / surrounds are manufactured by "soft parts" companies in most instances (several large companies make the majority of cones and surrounds that you see); then they go to the "assembly" company or "build house" from there -- so some stitching being a little off in no way represents the assembly quality of the build house / brand name or the overall performance of a driver. And yes; a prototype is often is a little rough as the parts are done one-off and all of the equipment isn't necessarily setup to run a bunch of them uniformly. Concentrating on such a minute detail reminds me of the expression, "not seeing the forest for the trees."

I will also confirm that the drivers are 100% not vapor-ware. They are being produced. I've handled the prototypes and I think people will really like them.

I dropped this driver in a 4.2 ft sealed cab tonight to see what kind of power it would take before excursion became a concern. Right about 75 volts it turns out. This driver in cab gives a min impedance right about 4 ohms. That equals a power of 1400w with 75 volts. Obviously this will change depending on the cabinet size and type but it does show that the driver will handle quite a bit of short term power in a sealed cab without running into mechanical danger.


EDIT: Basic impedance of above system that was fed 75 volts.


Edited by Ricci - 11/2/12 at 8:35am

@Ricci,
And now everyone is going to want distortion sweeps.
If it makes you feel better, I think I was the first person to bring up Le and it was because this woofer is supposed to have nearly 1 Le/Re. I'd hope not because I don't speak German. My wife would have to translate for me.

Can someone link a good place to order the SI subwoofer? I am interested in picking up a few of these.

HERE.

Has all of the discussion of this Sub moved to the HTS forum?

I ask because the recommended enclosure volume of the 18" on the website is 6ft^3. I have some ~3ft^3 raw boxes with an 18" cutout that I am planning on spending some serious time finishing out over the next few weeks. I initally designed the WAF box with the intention of experimenting with the TC Sounds Pro 5100, but it's just too expensive. I'm looking for a good 18" to fill the box and debating on this SI driver, the Dayton HO or the UXL-18. I'm leaning towards this becuase it seems to be the most cost effective option, though I may wait until Ricci finishes up his testing on the Dayton HO (supposidely) this weekend.

I have the miniDSP for fq shaping and should have the power that I need to make anyone of these drivers work in the "small enclosure." With that said, I haven't learned how to model subs, so I was wondering if someone could let me know if this sub would even be worth trying to implement in the box I have built and the actual power demands I would be facing to achieve xmax around 16Hz.

Thanks in advance!

Because there is nothing to talk about. No product exists yet for the public. But ... I can't say that though.

Just get the Dayton 18HO. It's out now and costs about the same as the SI 18HT driver which won't be avaiable til early 2013.

Without more testing from Ricci there's not really much to say until people get them in their hands.