They're here! "A Tale of Two Subwoofers" (and LCRs) - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
Reply
 
Thread Tools
post #1 of 58 Old 03-29-2007, 08:34 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
My two TC-3000 15" subwoofers arrived today. Oddly, so did the Crown XTi 4000 I'll be powering it with. I'll be building two sealed boxes of internal dimensions 18"x18"x20", which should give me about 3.6 cuft after bracing and driver area is subtracted. The Crown XTi 4000 has two shelf filters and 5 parametric EQs, which should take care of an LT to get it to reach low, as well as deal with room issues. The build will start in about two weeks when my parents come down to visit - my dad doesn't want me to have all the fun. I'll also be putting together three main speaker kits that Rick at Selah Audio designed for me (and a couple of other people). Together, they should be a match made in theater heaven. It's going to be scary in a sealed 2000 cubic foot room with these beasts pounding.

As my daughter's expression says: "Daddy, what were you thinking!!!"



I'll post pictures and measurements once I finish on the 8th. I'll also be posting pictures and measurements of the LCRs, a little later. Unfortunately the dedicated room won't be finished for another 5 months, so no pictures of that for a little while.

I want to give a special thanks for Kramskoi for showing us what these bad boys can do in the right room and with enough power. I also want to thank Rick for creating some serious speakers to match these subwoofers at reference levels.

Specs on the speakers:
3-way dual box
2x 8" Peerless Nomex, 2x Dayton RS150, Peerless HDS Tweeter
90.5 dB sensitivity
200 watts continuous, 400 watts peak
7 ohm nominal, 4.8 ohm minimum

Should be capable of reference level peaks from 3.5-4.0 meters. We'll see how they test.
Lindahl is offline  
Sponsored Links
Advertisement
 
post #2 of 58 Old 03-29-2007, 09:05 AM
AVS Forum Special Member
 
ssabripo's Avatar
 
Join Date: Feb 2004
Location: Plantation, Floriduh
Posts: 6,144
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 112 Post(s)
Liked: 48
nice! looking forward to your progress....
ssabripo is offline  
post #3 of 58 Old 03-29-2007, 09:11 AM
AVS Forum Special Member
 
Willd's Avatar
 
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 5,642
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Ahh yes, I saw that thread about those speakers a few days ago. They look like a sweet design.
Willd is offline  
Sponsored Links
Advertisement
 
post #4 of 58 Old 03-29-2007, 10:12 AM
AVS Forum Special Member
 
jpmst3's Avatar
 
Join Date: Dec 2005
Location: Davidsville, PA
Posts: 8,593
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 200 Post(s)
Liked: 316
Man, that is one mean pair of headphones!

______________________________________________
Joe = LFE Addict
Past Builds: 24" LMS-5400 cube, Anarchy 25Hz Tapped Horn, Danley DTS-10 kit, BFM AutoTuba, BFM THT, BFM THT-LP
Joe's LOWARHORN build, Dual LMS-5400 Ultra Endtables build
jpmst3 is offline  
post #5 of 58 Old 03-29-2007, 10:56 AM
AVS Forum Special Member
 
vitod's Avatar
 
Join Date: Dec 2003
Location: Pocono, PA
Posts: 3,640
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 287 Post(s)
Liked: 165
Congrats, but waiting for two weeks is cruel.

Panasonic AE-8000, Carada BW 120", Paradigm Studio 40v3 x 2, Paradigm 690v4, Paradigm ADP 470v3 (rears), Micca M-8C x 4, Volt 6 x 2 (SR), SI DS4-18 in 12cuft X 2, Marantz 7702MKII, OPPO 103D, Emotiva XPA-3,
vitod is offline  
post #6 of 58 Old 03-29-2007, 12:11 PM
AVS Forum Special Member
 
Exocer's Avatar
 
Join Date: Mar 2005
Location: The big apple
Posts: 1,873
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Liked: 10
Sweet! Audio nirvana... Congrats

My DIY Speaker Build: https://www.avsforum.com/avs-vb/showthread.php?t=684744
Current Equipment: Marantz AV7704, Rogue Audio ST-100, Tidal via HEOS
Backup Amps: Onkyo M504, Yamaha M60
Computer Setup: Topping DX7S Balanced out to JBL LSR 305 V1
Exocer is offline  
post #7 of 58 Old 03-29-2007, 12:27 PM
Member
 
graniteguy's Avatar
 
Join Date: Mar 2006
Location: Austin, MN
Posts: 134
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I love the look on your daughter's face. It's as if she know about the audible carnage that is about to take place. Or it could be that she realizes her inheritance is being completely depleted!
graniteguy is offline  
post #8 of 58 Old 03-29-2007, 09:07 PM
Advanced Member
 
mconno's Avatar
 
Join Date: Jan 2007
Posts: 501
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 12
As much as I'm impressed by the "gear", as a grand daddy , I'm more impressed by your daughter......she's a real cutie.
A little secrete, your dad is really coming down to see her. Grampy's are like that...you're on your own. Great luck !
mconno is offline  
post #9 of 58 Old 04-02-2007, 10:32 AM
AVS Forum Special Member
 
Nabs17's Avatar
 
Join Date: Apr 2003
Location: Wesley Chapel, FL
Posts: 1,755
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 920 Post(s)
Liked: 516
Please do post pictures of your build as it progresses. I am leaning towards the DIY sub route and after some preliminary investigation, I am leaning towards these 15" drivers as well. I was wanting to put them both into one box but I could go two separate boxes.

Very interested in your build.

Thanks,

Nabs17
Nabs17 is offline  
post #10 of 58 Old 04-29-2007, 11:39 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Ok, it's time for a big update. Click on the pictures to see larger resolution versions. Unfortunately I lost a lot of the pictures during the sub construction, but I do have some pictures that should be instrumental in explaining how it was put together, along with a Google sketchup file with the speakers and subwoofers modeled. I've attached it as a zip file to this post. I'll be more careful with the pictures I take during the speaker construction. Since both the speaker and subwoofer boxes were constructed in a similar fashion, you should be able to apply the same techniques.

Here's a picture of the Sketchup file, it also includes how I planned to cut the 6 sheets of MDF (three different cut sheets, mirror images of each other).


Arrival of Rick Craig's kit. The crossovers have been blurred to protect his intellectual property. The kit came with everything but stuffing and the boxes, even screws and gasket material.


Why DIY when you can get Home Depot to do it for you? Instead of buying a table saw, I had Home Depot cut all of the MDF - A LOT of it. Since Home Depot doesn't require you to pay for cutting anymore, I gave the guy a nice tip. I let him know that I'd be very thankful if he was careful with the cuts and got them as precise as possible. Probably not as good as using a table saw, but close enough for someone without any woodworking experience (me!).


I cut grooves in the panels that touch the bracing in order to hold the bracing better. Here you can see the inset grooves with the bracing in place. The grooves were a little smaller than the thickness of the MDF, so it was a real tight fit by sanding the edges lightly to create a wedge, before inserting into the slots.


After the first box was finished, I built another box around it. Since this is my first time doing a woodworking project, I figured I'd get a more airtight box doing a box within a box. Mandatory tool is a belt sander. The edges never perfectly aligned, and using a belt sander to sand it down worked well to make sure the outer layer of the box didn't have any airgaps in it. Technique is critical when doing this. Don't ever sand for a long period in one location. Really go over the entire box with the belt sander in large circles, moving it around and changing position. If you don't do this, it's very easy to sand down a small part of the box too much, which can create airgaps such as these - mostly you just have to watch the edges and corners:


The fix is to mix wood glue with all that sawdust you created with the driver cutouts. Use the paste that's created to fill in the gaps. It's better than nothing, at least.


Here are both boxes with only the inner layer completed.


Here are both boxes with still a ton of MDF left, for the second layer of the subwoofers and the 3 identical two-box LCRs.


I'm currently using one subwoofer box for a workbench, since the huge driver cutout makes a convenient way to add clamps when building the speakers. Since my current speakers aren't quite up to the task of high SPL, one subwoofer works just fine, for now. The subwoofer is configured for a nominal 8 ohm load, and the amplifier is bridged, providing 2400 watts at 8 ohms. 14 gauge wire was enough (doesn't get hot).

 

speaker + sub cuts.zip 74.34375k . file
Attached Files
File Type: zip speaker + sub cuts.zip (74.3 KB, 52 views)
Lindahl is offline  
post #11 of 58 Old 04-29-2007, 11:39 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Unfortunately that's it for the subwoofer pictures. Now for the room and measurements. We moved from another (unaffordable) state into our current house about two months ago. I was able to get a basement that, by moving one wall, and building another would give me a 21'x13' space to create a dedicated theater. We're planning on construction in a while from now, since I'm spending quite a bit of money on equipment. In the meantime, we get to enjoy a haphazard theater built in an open portion of the basement. The brown bed sheet on the floor is covering all the speaker drivers and crossovers to keep the dust off.


You can see my old subwoofer just to the left of the left speaker, along the side wall. Yes, it's a reeeaaalllly tiny 8" ported subwoofer. The response isn't too bad for a single 8", but the placement is pretty terrible. The main problems are the 20hz, 50hz, 70hz and 90hz nulls. The new subwoofer had the same problems at those frequencies.


I tried several placement options before settling on this one.


It still has a couple nulls at 40hz and 72hz, but they're both pretty narrow and the 40hz null is pretty tame. A second subwoofer, well placed, should help out. You can see the normal inductance peak at around 60hz and a smaller room peak at around 30hz. The most amazing part of this placement is the room gain. After seeing the gain I was getting, it was a no-brainer to leave the sub where it was. When they say it's all about room placement, they really mean it.


Using the well-engineered System Architect software and the Crown XTi's DSP, I applied several filters to tame the peaks in the original response. But with the amazing room gain I'm getting, I didn't have to apply a single boost! The available 5 parametric filters are more than enough to flatten the response - I only had to use three.


Ignoring the nulls, the FR is flat to 10hz and +/- 3db to 7hz with a very slow rolloff afterwards. I still can't believe it. Some may say it's the measurement equipment boosting the lows, but with the old placement, the boost down low didn't exist and it rolled off pretty quickly and early. It required a couple stacked PEQs at 20hz to get it flat to 20hz. As additional proof, you can see my nearfield measurements here. It's almost sad to build a dedicated room, and lose all that room gain!
Lindahl is offline  
post #12 of 58 Old 04-29-2007, 11:39 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Well, I'm done and loving it! The speakers are incredible, especially for the price. The night after I finished them, the wife was struggling to get me to go to bed, while I just wanted to sit back and enjoy the music. There's still a bit of work to do in treating the room and subwoofer integration. The speakers are going to stay unfinished, and I'm not going to bother doing roundovers, or sanding the edges flush until I have the contractors start on the dedicated room (and my temporary theater is out of commission). I'm still waiting on the XLR-RCA cables, so I haven't been able to fire the system up past 95db peaks. I'm really looking forward to that, though. Incredible imaging, good midrange detail, and smooth treble are definitely the strong points of these speakers. These are THE speakers to have for a dedicated theater (and just as good for music). The imaging is incredible, except for one thing. With the bass bins, they image a bit lower than I'm used to, so I'm talking to Rick Craig about this to see if we can bring the image up any higher while keeping the tweeter at ear level.

So... without further ado, construction updates:

I decided to first glue the bracing to the back panel. In order to get it lined up as best as possible, I used some larger MDF pieces and some clamps to get the edges as parallel and flush as possible.



After setting up the guides, I marked the placement of the central horizontal brace on the back panel and central vertical brace.



Using the markings, I was able to line up the crossbrace without the guide.



Add balancer pieces in the middle, so the central panel and back panel are parallel, and clamp away.



Once the bracing pieces were glued to the back panel, I glued the front panel to a side panel, using a balancer piece again, this time to get a good perpendicular joint.



Next, I added the bracing structure to the same side panel.



Finally, it was time to sand the bracing, front and back panels so that they were as flush as possible to provide a good surface to glue the second side panel.



Using a large piece of MDF, I checked for flushness by sliding it up and down on all sides of the bracing and front/back panels, looking for gaps.



Here's a picture of all six boxes sanded and ready for the second side panel. Also shown is my workbench (aka: the subwoofer)



When adding the second side panel, it became obvious that there were some issues in getting the edges flush.

Lindahl is offline  
post #13 of 58 Old 04-29-2007, 12:11 PM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
So by clamping the front and back panels lightly, I was able to get flush edges and a good glue joint for the second side panel.



Once I got the edges flush, I added clamps for the four corners to hold the edges flush.



Finally, I was able to get the side panel glued down and clamped.



The next step was to get the top and bottom of the boxes sanded flush to provide a nice and flat gluing surface for the top and bottom panels.



Since I wasn't able to sand it perfectly flat, the clamp positions were chosen precisely to close any additional small gaps that I wasn't able to sand away. I clamped the bottom and top separately, so it took a little more time, but it made it easier to line up the edges so they were as flush as possible.



Since I was going for a double thickness baffle, and the RS150 midwoofers aren't very deep, I needed to route out some larger holes in the first front panel to make sure the midwoofers had plenty of breathing space.



Finally, I was able to glue the second baffle, again, sanding the surface flat as possible and positioning the clamps in the best position to close any gaps.



With the boxes done, I was ready to begin the driver cutouts. I used a piece of scrap MDF to test out cutout sizes to make sure everything fit as tight and as flush as possible. You can see the large cutout I did when testing cutout sizes for the subwoofers.



Before I began doing the driver cutouts for the MTMs, I realized I made a huge mistake. The midwoofers are off center, and I completely forgot to mark which side when I had done the pre-cutouts for midwoofer breathing space. Doh! So, before I began the cutouts, I used a drill and did some calculations such that I could make a single drill hole to determine on which side the cutouts were supposed to be biased. This way, if I was wrong, I only had to fill a small drill hole. I spent about about 15 minutes rapping my knuckles and listening carefully, to try and avoid drilling the small hole on the wrong side. Turns out that I had guessed right every time! So with some confidence, I began the rabbits.



I was still sweating a little bit, just in case the drill holes didn't tell me properly, but once the driver cutouts were finished, I knew that everything was golden. That was a close one!

Lindahl is offline  
post #14 of 58 Old 04-29-2007, 12:11 PM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Even though the woofers aren't flush mounted, I did some rabbiting to give more strength to the baffle.



Here's a shot of all six boxes ready for pre-screw drilling.



Now for the fun stuff... wiring up the drivers and securing them in place.



I went with outboard crossovers so I can tweak till the world ends. I'll be building boxes for them eventually, but this is good enough for now.



All done and wired up, ready for first testing.



Shot from the sweetspot. Note that the MTM box for the center speaker is missing. One of the tweeters was pretty much DOA. The upper frequencies were all but missing, very odd sounding for sure. Rick Craig is taking good care of me on this problem and another one is on it's way as I type.



TC-3000 stackage.



Here's a shot from the back of the room. Notice the two projectors. The Sharp 12K is WAY better than my older Panasonic AX100, which is going back to Costco in a week or so. Unfortunately the Sharp is pretty loud, about as loud as the amplifiers with their makeshift hushbox - which you can see behind the subwoofers - it's two sheets of gray egg-crate foam boxed around the amplifiers. I'll definately be making a hushbox for the projector too (one with better cooling, obviously).



Here's a shot from the front of the room looking back at the equipment. I'm using a Denon AVR887 as a pre/pro, with an X-box above it and a Sony 400-disc DVD player below it. The amplifiers behind the gray foam are 1 Crown XTi 4000 and 4 Crown XLS 402Ds. Whenever I get an HD-DVD in from Blockbuster online, I bring home the HD-DVD player we have at work (we do custom software jobs for various AV companies).



Finally, here's the measurements of both mains. As you can see, I'm having serious room issues around 100-600hz, which is very noticeable on lower toned male voices, like Hugh Jackman in The Fountain (lots of breathiness). Sub integration needs some work, as well (70-90hz). The combing up top is due to two speakers playing the same signal, on top of not having any roundovers (which are spec'd for this design). With one speaker, the combing is about +/- 2.5dB. Overall, not bad at all, IMO - almost +/- 5dB in a completely untreated room from 10hz to 20khz.





** ATTENTION **

The below posts are in response to my initial subwoofer build posts. The speaker build posts were added later, in an attempt to keep all of the build pictures and information in one place.
Lindahl is offline  
post #15 of 58 Old 04-29-2007, 02:30 PM
AVS Forum Special Member
 
Willd's Avatar
 
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 5,642
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Could you change the graphs so they don't range from ~5Hz to 635Hz? 10-100 would be better...anything around that...just not 5-635.

Thanks!

And not a bad job on those enclosures for having Home Depot cut the wood!
Willd is offline  
post #16 of 58 Old 04-29-2007, 05:08 PM
AVS Forum Special Member
 
TheEAR's Avatar
 
Join Date: Nov 2006
Location: Montreal,CANADA
Posts: 3,451
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 13
Lindahl,

Good work,keep the pics comming.I will be building a similar sub,dual TC-3000 and Crown XTi 4000 to power them.

I will follow this thread close...

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
TheEAR is offline  
post #17 of 58 Old 04-30-2007, 12:58 PM
AVS Forum Special Member
 
soho54's Avatar
 
Join Date: Sep 2005
Posts: 3,343
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 24

That is a funny mic/soundcard correction filter you have there.
That seems to be an abnormally peaky natural FR as well.

I would try to figure out what is causing the weird correction filter before I tweaked them much more. I have seen a bad connector/wire in my mic setup cause something similar to that 300Hz area squiggle. My creative drivers wonked out one time as well with similar results. The thing is it threw off all frequencies not just the ones that showed up in the correction filter.

Since then I always run a base line sweep on a known old POS Sony speaker to make sure everything is on the up and up. My computer set up is in a constant state of flux, so it might just be my problem.

You could be fine, just thinking aloud.
soho54 is offline  
post #18 of 58 Old 04-30-2007, 01:12 PM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Quote:
Originally Posted by soho54 View Post

That is a funny mic/soundcard correction filter you have there.

Thanks, I'll look into it. Sometimes I do get blips and the like when doing sweeps, but they're never at the same frequency and random (often getting none at all). I could be having some soundcard distortion issues (MobilePre USB).

Quote:


That seems to be an abnormally peaky natural FR as well.

Looks normal for the TC-3000 - pretty close to the model, peaking around 70hz and about -15 db at 20hz. The hump at around 30hz is due to a room mode, I think. Or are you talking about the serious combing between 100hz and 200hz?
Lindahl is offline  
post #19 of 58 Old 04-30-2007, 01:36 PM
AVS Forum Special Member
 
soho54's Avatar
 
Join Date: Sep 2005
Posts: 3,343
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 24
Quote:


Looks normal for the TC-3000 - pretty close to the model, peaking around 70hz and about -15 db at 20hz

This is what I was talking about. I'm at work now, so I couldn't model it. Just use to the other TC drivers I guess. Looking at the specs now I can see it is a different beast.

Looks like an old dual P2 box, I had years ago.

Quote:


Sometimes I do get blips and the like when doing sweeps, but they're never at the same frequency and random (often getting none at all).

Yeah, this is what mine would do as well. I looped the input and outputs together ran the calibration again, and ran a sweep then changed the loop cable out and tried it on a second one. If it is a cable the blip will be gone. If the blip stays regardless of the cable it is a software gremlin.

To double check the software problem run a sine sweep on another program (WMP) while looped, and record the returning sound in CoolEdit or something. Now check the recorded wave against the original. I found that there would be amplitude variations all through out the recorded sweep. Time to uninstall the sound card, and set it up again.
soho54 is offline  
post #20 of 58 Old 04-30-2007, 01:58 PM
AVS Forum Special Member
 
Join Date: Jun 2005
Posts: 5,020
Mentioned: 17 Post(s)
Tagged: 1 Thread(s)
Quoted: 1296 Post(s)
Liked: 738
Quote:
Originally Posted by soho54 View Post


That is a funny mic/soundcard correction filter you have there.
That seems to be an abnormally peaky natural FR as well.

That response is about what one would expect for a driver with inductance as high as the TC3000's. And even after the FR is tamed the energy-storage issues of hgh-Le drivers remain. The TC3k is probably a great driver for home theater bombast, though.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
DS-21 is offline  
post #21 of 58 Old 04-30-2007, 02:09 PM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Quote:
Originally Posted by DS-21 View Post

That response is about what one would expect for a driver with inductance as high as the TC3000's. And even after the FR is tamed the energy-storage issues of hgh-Le drivers remain. The TC3k is probably a great driver for home theater bombast, though.

Actually, you only get the high Le when wired for 8 ohms. It's much lower if you wire for 2 ohms. Do a search on Le with poster being "TC Sounds". At least that's the way I read it... either or, linearity is a much bigger problem with respect to SQ.
Lindahl is offline  
post #22 of 58 Old 04-30-2007, 05:04 PM
AVS Forum Special Member
 
Join Date: Jun 2005
Posts: 5,020
Mentioned: 17 Post(s)
Tagged: 1 Thread(s)
Quoted: 1296 Post(s)
Liked: 738
Quote:
Originally Posted by Lindahl View Post

Actually, you only get the high Le when wired for 8 ohms. It's much lower if you wire for 2 ohms. Do a search on Le with poster being "TC Sounds". At least that's the way I read it... either or, linearity is a much bigger problem with respect to SQ.

It's kind of silly to argue that you're not dealing with an inordinately high inductance driver when your own measurements betray a ~12dB inductive peak in the upper bass. Wire it for 2ohms and watch that peak not go away! Because on an Le/Re basis it's still the same, and more than double that of the TC woofers noted for their high sound quality such as the TC2+/TC1000. If the inductance is modifying the frequency response that much, there is also significant energy storage that can't simply be fixed with EQ like the FR can. And linearity is highly related to energy storage...

Here's a good thread from the AVS archives about inductance.

Not that with proper EQ, as you seem to be doing, a woofer with excessive inductance can't sound pretty decent. Especially for movies, because "fidelity" is a really nebulous concept when all one's trying to do is recapture synthetic events. But with similar attention to detail (box construction, placement, EQ, etc.) a driver with lower inductance will have greater audio fidelity.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
DS-21 is offline  
post #23 of 58 Old 04-30-2007, 09:32 PM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Quote:
Originally Posted by DS-21 View Post

It's kind of silly to argue

Not really arguing, just pointing out what someone else said on the topic. I don't have enough knowledge in this area to really discuss. Either or, backing up your statements with more of your statements doesn't really help (not saying you're wrong). I guess I was hoping the link would lead to another party talking about inductance and linearity (and it did, somewhat with the quote from Hiddley and Geddes). Thanks for the education, anyhow.
Lindahl is offline  
post #24 of 58 Old 05-01-2007, 09:02 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Quote:
Originally Posted by DS-21 View Post

It's kind of silly to argue that you're not dealing with an inordinately high inductance driver when your own measurements betray a ~12dB inductive peak in the upper bass.

Actually, the inductive peak is quite a bit smaller than 12 db. It looks like a much larger inductive peak, due to the nature of the sealed alignment. Here's the TC-3000 modeled in 3.6cuft with and without the inductance added to the model. I'm not exactly sure how to interpret the graphs, but it looks closer to a 4 db inductive peak across the passband. I would think that other SQ issues would dominate the energy storage issues you talk about, especially considering an 80hz crossover to the mains, around where the inductance peak is at its worst. Though, I think several distortion tests are imminent just to see how much of a problem is this energy storage that you speak of - just to satisfy my curiosity. That should be sufficient enough, no?



On a side note, I enjoyed your critique about dynamic compression of the mains in the Jai's thread. If you want to offer up any comments on the dynamic compression pairing between my speaker and subwoofer configuration, I'm all ears to any critics.

Quote:
Originally Posted by Willd View Post

Could you change the graphs so they don't range from ~5Hz to 635Hz? 10-100 would be better...anything around that...just not 5-635.

I didn't save the measurements, so I'll try to find some time to run a few more sweeps with better resolution. My struggling lawn and speaker build are taking top priorities during my afterwork hours . Keep in mind that I'm not smoothing my graphs. Maybe I'll add a smoothed one so people can compare it with other peoples' graphs (it looks like most tend to smooth them).

Quote:
Originally Posted by Willd View Post

And not a bad job on those enclosures for having Home Depot cut the wood!

Yeah, the enclosures are pretty strong. As with any single-driver sealed box, you can definately feel vibrations when it's pushed, but they aren't enough to add any coloration at the seats (or even nearfield), so that's good! I haven't added stuffing yet, I'll do that when I (again) get some time. But it won't be happening today, since it's my birthday.
Lindahl is offline  
post #25 of 58 Old 05-01-2007, 09:11 AM
Advanced Member
 
Richard Mayer's Avatar
 
Join Date: Oct 2006
Posts: 861
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Lindahl View Post

Actually, the inductive peak is quite a bit smaller than 12 db. It looks like a much larger inductive peak, due to the nature of the sealed alignment. Here's the TC-3000 modeled in 3.6cuft with and without the inductance added to the model. I'm not exactly sure how to interpret the graphs, but it looks closer to a 4 db inductive peak across the passband. I would think that other SQ issues would dominate the energy storage issues you talk about, especially considering an 80hz crossover to the mains, around where the inductance peak is at its worst. Though, I think several distortion tests are imminent just to see how much of a problem is this energy storage that you speak of - just to satisfy my curiosity.


Unfortunately WinISD doesn't model inductance properly. Try Unibox for more accurate models. It uses the more accurate triple value model (Ls, Lp, Rp).
Richard Mayer is offline  
post #26 of 58 Old 05-01-2007, 09:43 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
Quote:
Originally Posted by Richard Mayer View Post

Unfortunately WinISD doesn't model inductance properly. Try Unibox for more accurate models. It uses the more accurate triple value model (Ls, Lp, Rp).

Can anyone do this for me? We use OpenOffice at work, so I don't have Excel to manipulate it (the graphs, buttons and pop-ups don't work in OpenOffice). For what it's worth, I don't recall the difference between the two being all that big. In fact, I believe it was in favor of the Unibox model. I'll model it when I get home, unless someone else jumps in.
Lindahl is offline  
post #27 of 58 Old 05-01-2007, 10:00 AM
Advanced Member
 
Richard Mayer's Avatar
 
Join Date: Oct 2006
Posts: 861
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Inductance included



No inductance

Richard Mayer is offline  
post #28 of 58 Old 05-01-2007, 10:15 AM - Thread Starter
AVS Forum Special Member
 
Lindahl's Avatar
 
Join Date: Dec 2005
Posts: 1,847
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Liked: 23
A bit worse than what WinISD shows, but not quite a 12 db peak - more like 6 db. Come to think of it, that's about what my nearfield response shows. Thanks, Richard. After doing some reading, it appears that a simple impulse response would better reveal whether or not the energy storage of the TC3000 is an issue. Spectral decay plots, may help as well, but now you're looking at multiple types of energy storage. Perhaps look at an impulse response, and then look at the spectral decay plot for that frequency and determine if the energy storage in the TC3000 due to inductance takes a back seat to other forms of energy storage. Or, on the subjective side, listen to a lot of material with quick transients (i.e. kick drums). Is this the part where you felt high-inductance subwoofers to be amusical, DS-21?

From some of the subjective tests I've made, I don't find the single subwoofer to be lacking in transient response. IMO, it has plenty of attack and a quick decay for both movies and music, and I certainly don't notice any ringing.
Lindahl is offline  
post #29 of 58 Old 05-02-2007, 04:43 PM
AVS Forum Special Member
 
Join Date: Jun 2005
Posts: 5,020
Mentioned: 17 Post(s)
Tagged: 1 Thread(s)
Quoted: 1296 Post(s)
Liked: 738
Quote:
Originally Posted by Lindahl View Post

Actually, the inductive peak is quite a bit smaller than 12 db.

I guess it depends on where you think of the inductance effects starting and stopping.

Here's an example of the FR of a woofer I find to sound excellent, Peerless's XXLS12.



Note the utter lack of an inductive peak. (Complete measurements of the XXLS 12, and many other drivers of interest to DIYers are here. N.P. Dang is a huge asset to the DIY audio community at large, no matter that his primary focus is car-fi. I don't think anybody else has published so many Klippel measurements of drivers for free public perusal.)

Correlating measurements with my basket of sonic impression of different systems really makes me think that for high-fidelity bass reproduction multiple woofers with more moderate excursion capabilities and very well designed drive systems. Seaton's Submersive seems to take a similar path: not-quite he man drive units, but plenty of cone area and thus Vd despite that, combined with intelligent application.

Quote:


I would think that other SQ issues would dominate the energy storage issues you talk about, especially considering an 80hz crossover to the mains, around where the inductance peak is at its worst.

I'm not saying that energy storage is the most important thing, just something that particularly bothers me.

Quote:


On a side note, I enjoyed your critique about dynamic compression of the mains in the Jai's thread. If you want to offer up any comments on the dynamic compression pairing between my speaker and subwoofer configuration, I'm all ears to any critics.

It is obvious from your post thus far that you've put a great amount of thought and attention to detail into spec'ing your setup. Those Peerless HDS woofers are outstanding performers. I do not foresee a problem with them used at an 80Hz Fc, or even assuming a 4th order HP maybe 60Hz. You also avoid midrange excursion-modulation issues at high SPL by going with a true three-way design with identical LCR. You also have quite a lot of sub, so from a dynamic compression POV it looks like a great combination. Admittedly, I would've gone for something different on top (a B&C 8CX21, maybe their new 8CXT, or if cost were more of a limiting factor one of the Seas coaxes) but I prioritize consistency of the power response in the midrange over ruler-flat on-axis treble FR, whereas RC is very much about perfect FR. In all, though, I wouldn't imagine there are many (if any) commercial HT systems for under $25k that will achieve the level of performance you will with those parts and the attention to detail you've already shown.

--
"In many cases there aren’t two sides unless one side is 'reality' and the other is 'nonsense.'" - Phil Plait
Serious Audio Blog 
DS-21 is offline  
post #30 of 58 Old 05-02-2007, 06:20 PM
AVS Forum Special Member
 
Willd's Avatar
 
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 5,642
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:


Note the utter lack of an inductive peak. (Complete measurements of the XXLS 12, and many other drivers of interest to DIYers are here. N.P. Dang is a huge asset to the DIY audio community at large, no matter that his primary focus is car-fi. I don't think anybody else has published so many Klippel measurements of drivers for free public perusal.)

Correlating measurements with my basket of sonic impression of different systems really makes me think that for high-fidelity bass reproduction multiple woofers with more moderate excursion capabilities and very well designed drive systems. Seaton's Submersive seems to take a similar path: not-quite he man drive units, but plenty of cone area and thus Vd despite that, combined with intelligent application.

Indeed N.P. Dang is a wonderful resource. I check out his tests quite often.

And for reference, here is a free air measurement of the 15" TC-2000, courtest of Ilkka.



And of course if one was to match the resolutions of the two graphs, the difference wouldn't be that significant.
Willd is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off