Another 15TC-2000 qurestion for the experts...

Sort of, but you'd really be better off building the enclosure yourself or finding someone that would be willing to help you with it (whether it be tools or experience, say, for some beer).

I'd say the 15" TC-2K would like at least 3ft^3 per driver, and they can take a lot of power. You'd want something like the Behringer EP2500 at the minimum, IMO.

I really wouldn't recommend the Dayton rack mount amps. They are too expensive for the amount of power they provide, and they have a very sharp drop off in response after about 20HZ or so. You'd be far better off with two Behringer EP-2500s for the money, or even a pair of better pro-amps.

The Soundsplinter Rl-p 15's are closely related to the TC-2000.

Here is what one guy did with 4 of them in sealed boxes.

http://www.htguide.com/forum/showthread.php4?t=23365

His thoughts: http://www.htguide.com/forum/showpos...3&postcount=76

Cost aside, the TC-2000.

The measurement is made available by Parts Express. http://www.partsexpress.com/pdf/300-808response.pdf

The single-band PEQ included is basically useless. You can get a much more functional/useful PEQ for $99. Auto turn on can be accomplished other ways.

In what way were you using the EP2500? Whether you were blow away by it or not, it no doubt has much more power than the rack mount amp in question, and it also doesn't have such a poor low frequency response. Hell, you'd be better off with the Buttkicker BKA-1000 than the Dayton amp IMO.

As lofty as the ratings may be, something was wrong with your setup. The EP2500 could not have been clipping due to running out of steam with those two subs. Hell, the power handling of the CS 20-39's is rated at 350W @ 4ohms by SVS. You should have been bottoming out the CS' before reaching the Ep2500's limits.

Sounds like you had the high pass filter turned on. I played with mine with the HP filter set at 30hz, 50hz and off. 50hz was obviously no bass. 30hz, you could hear some bass but it just didn't have the impact. I turned it off and THERE WAS BASS!!!! And this is with one channel @4 ohms driving a pair of 15's.

I had the mis-marked DIP switches so it took so testing to find the correct settings.

Any reasons for not looking at the TC-3000? There has been at least one small, sealed sub built with a pair of 3000's and an EP-2500. The results were quite impressive.

-Robert

For my money, the TC drivers (including the Sound Splinter drivers), which are overhung, big coil drivers simply have too much inductance to be seriously considered for a sealed system. The aluminum cone is a bit of trouble as well, in my experience of using the TC based AE drivers as well as others over the past 5-6 years. It just doesn't have the longevity that other modern composites do.

The Dayton ref series drivers look nice on paper, with very low Le and very high efficiency.What you lack in throw you could make up in multiples. Thomas' post in the thread Will linked to:
"No doubt the HO's model better than the others you mentioned. That would be apparent just looking at the T/S parameters (the Le in particular). And using 4-HO's is going to give you a very nice high sound quality setup..."
Says it all.

The really overlooked driver, IMHO, has been the Adire Brahma MK IV. Very low inductance (2X.22mh on the 15D2), XBl^2, and I hear the new cone is a Hemp Acoustics composite, so when you decide to upgrade you can break up the cone a smoke it .

I have a 2X15" Brahma sealed, L/T here. About 12dB of boost with selectable system Q, fed by 2,700 watts, and it is superb. Kyle offers them for $379, shipping included, and ask for the Bosso discount if you plan to order more than 2 (he always gets a kick out of that one )

Bosso

Right now I'm using my own rack mount amps. I use one amp per each dual driver, D2. 2,700 watts into 8 ohms bridged.

I got tired of looking for the right amplification specs and features and decided to ODM a couple of designs off of existing class H platforms. HP at 3Hz, enough juice to run a dual 15" sealed sub off a single 20 amp dedicated outlet, noiseless fans, etc., etc.

I have 2 versions being tested. It'll take a while for the whole process to be complete, as I do it as a hobby to this point. When my latest system is completed, I might explore ordering the amps in quantities because they really (so far) are great amps for the money.

Some more details of the system on my site...more measurements, details, etc., as I have them, will be posted on the site for those who may be interested:

http://web.mac.com/bossobass.com/iWeb/Site/Welcome.html

Good building and keep us informed as you get into it.

Bosso

ouch!...now you've thrown down the gauntlet!...

although i can't speak to potential flux modulation issues, which would be my biggest concern here, the TCQ5 has acquitted itself quite favorably...even at 10 Hz



i agree that the high Le has negative implications for linear FR, among other things, but it's nothing a little (or a lot) of eq can't rectify...anyway it's my only solution so i have to ride it until more suitable drivers (4100 Neo) are released from TC Sounds...and i'll tell you that it ain't some "ole paint"...this horse can unearth some startling theatrics...and it's about to get some new hoofs...moving up to 3.1 kW with a QSC PLX3102...the ep2500 ain't cutting it...i've grown weary of the behringer clipping lights...the drivers totally eat that amp. The QSC, with Power Light Technology, should provide some real power.

What makes having lower inductance more important in a sealed system as opposed to a vented one?

And is a an Le of ~2.5mH really detrimental to performance below 100Hz?

in single driver implementations...the sealed driver usually presents higher distortion simply because it moves more than a comparable vented system...adding the potential flux distortion, along with suspension nonlinearites and hysteresis from higher excursions and it becomes a serious problem...the high Le causes the top end of the subwoofer to rolloff rather prematurely...like a built in low pass filter if you will...it becomes harder to mate the subwoofer to the lcr and surrounds, especially if they are of the smaller variety...

the high inductance imparts a hump to the FR...the higher the inductance, the higher the hump...add a voice coil under load and your nice theoretically calculated small-signal response curve goes to crap, with the corresponding effective Q of the enclosure raised...that's why single driver sealed system are really at a disadvantage...from my sub, it was in the 60-80 Hz area...depending on your room, it has to be eq'd flat...sometimes you get lucky, sometimes not...this is my best stab at your question...i've been out the loop a few months so maybe some more knowledgeable guys can speak to this...

I think if the Le were to be too high, the alignment would be too peaky. In a sealed system, anyway...

I say sealed because, firstly, this thread is about a sealed build.

Secondly, it's generally accepted that a second order system is preferred for critical listening, because of it's better potential for the best transient response. This is partly because the roll off profile is very user controllable vs any other alignment.

It's also important to maintain a flat anechoic response to an octave above the crossover point. Yes, as Kram points out, EQ can fudge the in room response somewhat, but it robs the system of headroom in that critical area of BW.

A ported sub uses less amplification and so it has less headroom to begin with from 40Hz through the crossover region. Since headroom for transients in that region is critcal to accurate reproduction, I would assume that accuracy was not the motivating force in deciding to build a ported subwoofer. They are cheaper to build and more efficient at tune, the down side being the physical size.

If your crossover point is one octave below the Le induced corner, you're OK. Otherwise, your Le can be considered too high. Some may call that a strict standard, but those would be folks who lack experience on this subject.

Since transient response is limited only by frequency response, the subwoofer has much more potential to accurately reproduce transients in the crossover region than the mains and a sealed L/T system has the most potential for the best transient response...

I would say that a high Le driver is not the best candidate for a sealed sub...as I said...for my money...YMMV

Bosso

I suppose I should have PMed you...I shouldn't have mentioned vented among you guys. Thanks for the info though...



How can one figure out where this Le induced corner is? Measuring or simulation?

It's just like a 1st order low pass filter.

http://www.selectproducts.com/calculator_crossover.html

Just enter the impedance (you should use the Re value) and frequency, and the program gives you the inductance. Play with the frequency value until you get the correct inductance.

So for example TC-2000 15": Re 3.19 Ohms, Ls 2.45 mH -> corner frequency is ~207 Hz.

TC-3000 15": Re 4.63 Ohms, Ls 9.2 mH -> corner frequency is ~80 Hz.

LMS-5400 15"/18": Re 4 Ohm, Ls 1.5 mH -> corner frequency is ~424 Hz.

Tumult 15D2 MKII: Re 2.8 Ohms, Le 0.6 mH -> corner frequency is ~743 Hz.

Brahma 15D2 MKIV: Re 3.2 Ohms, Le 0.44 mH -> corner frequency is ~1158 Hz.


If you feel like calculating it yourself, the formula is:

Frequency = (1000 x Re) / (Ls x 6.283)

I see no reason why it wouldn't be.

edit: enclosure net volume for two TC-2000 15" should be in the range of 145 liters (0.707 Qtc) - 240 liters (0.6 Qtc).

Thanks a lot for the info Richard.

Measuring.

And, I'll patiently await a flat-to-207Hz graph of a TC2K

In the meanwhile, AVTalk and Ilkka and Ed have all measured the responses of the TC Sounds overhung motors. Every one of them has the hump at 50-60Hz, followed by a 1st order roll off as frequency increases.

Bosso

I have one here somewhere I'll sell ya for a good price. Very low hours.

IIRC, don't you have to make your own cabling to run the XLS series in bridged mode?

Bosso

Which ones have AVTalk, Ilkka, and Ed measured specifically? I know that Ilkka will eventually be testing a TC2K build which should be interesting.

How should I go about testing my TC2K? Just do a near field measurement?

All of the SVS subs are similar platforms, TC overhungs. Reportedly, they're building in house now and have begun to address the inductance issue, but all of the test results to date are of models with TC overhung drivers (except for the Ultra, which is an underhung, but still had many turns of wire...8 layers or more, IIRC).

I don't think near field is the best method for overall FR of a sub. I'd use 1M distance. Even though the room's influence will be present, a trend should also show up.

If you're using your A/V receiver, you'd probably have to take the signal off one of the front outputs with the speakers set to 'large', to avoid any filters?

Bosso

Indeed, some of the SVS drivers used to be TC made, and the new ones may be similar, but certainly that does not mean their measurements are enough to suggest the ones you can currently buy from TC sounds will measure the same.


Yeah, I am worried about the room. If I felt like it I'd take it outside.

I definitely thought about the signal aspect. I know the LFE lowpass on my receiver is limited to 200Hz, so I just decided to hook my sub straight up to my computer so that is one less problem to worry about. My lowly buttkicker amp is flat to at least 200Hz, and I believe just 2dB down at 300Hz, so that shouldn't be an issue.

We'll see.

Nevermind. This isn't going to work. This setup is useless (my room has too many issues as well, vibrations too). I suppose we'll just wait till Ilkka can test one. He has a good setup and will test it outdoors too.