2 x 15" TC-3000 Sub

[DennisP]

Lurking for a long time, first post!

I noticed these drivers on TC's website, and they look stellar. I was inspired by the recent 2 x15 SS vented monster another member built and I'd like to do something similar with the TC-3000 drivers, which should provide even more output (based on the specs.)

I'd like to lay the box horizontally, since it will probably be tall (I haven't modeled it yet, kind of a newbie). I'd love to keep it to 27"H x 30"D x 52"W (outside finished dimensions) and tuned to 16HZ. The drivers are quad 1 Ohm coils, so can I wire each one with one 4Ohm channel of a 2 channel pro amp? If that's the case, then 1000W at 4Ohms should be enough power (per driver). Am I making sense, or am I nuts? :P

I have to mention again that I'm a newbie at this stuff, and my woodworking skills are not great, but I have access to people (brother in law, father in law) with tools and more skills than I have that I can con into helping me build a box. I have Unibox and have played with it a little bit, but admit I'm a little confused at all the parameters (and am annoyed that every mfr seems to post in different units for different parameters!)

Any help would be greatly appreciated!

-Dennis

[SteveCallas]

Post the T/S parameters for those drivers and I will see what I can come up with. You've set the bar pretty high with trying to beat Steve nn's sub

[DennisP]

Here they are... 8)

15" TC-3000 QVC

Qts 0.260
Qes 0.275
Qms 4.950
Fs 19hz
Res 5.28Ω
Ls 9.2 mH
Lp 20.2mH
Rp 27.66Ω
Dia 325mm
Vas 205.1l
mms 329.5g
cms 212.2m/N
bl 29T*m
Spl 89dB

For more info:
Link!

[Jack Gilvey]

Holy Inductance, Batman!

[Bent]

Yup, hook a 1.5 volt battery to those windings in series, break the cct and the colapsing field will let you pull a 1 foot arc off the terminals, :ROFLOL

[ThomasW]

This should get you started. I used the Sd from another driver since one wasn't provided
It's going to take a HUGE diameter port to get the Mach numbers reasonable....

[DennisP]

Thanks Thomas, I'll plug into Unibox and see what happens!

[Amphiprion]

I think you would be better served by the TC-2000 series for high quality audio apps, the 3000 line looks geared more for max output rather than output linearity (I'm just guessing this looking at the coil and gap geometries). I think the TC-2000 look like they would be fantastic units.

Also, TC is supposed to be coming out with passive radiators to match the drivers. I would very much prefer using something like that to a port, if it looks like you're going to be running into vent mach problems.

[kramskoi]

This should get you started. I used the Sd from another driver since one wasn't provided
It's going to take a HUGE diameter port to get the Mach numbers reasonable....

winisd pro auto-calculates Sd=830 cm^2...IF this is true then...5.64 liters Vd swept !!! 8O vs. 4.86 liters for a Tumult 15d2...incredible! :E

[SteveCallas]

Hmm, nothing spectacular on my first go at it. What is with this trend of newer drivers having a big dropoff starting at ~80hz and hitting -3db so early? Is it a flaw in modeling software or what parameter causes this? The SS RLp15 has it too.

The excursion capabilities seem kinda wasted because it doesn't want a very large enclosure and it probably won't want to see more than 1000 watts for very long. By not liking a very large enclosure (I'm at 200 liters with a 15-16hz tuning to get it reasonably flat and balanced) it won't have very good sensitivity with a very low tune. It seems better suited to sealed or IB because a whole lotta that excursion isn't being used with a 15hz tune and 1000 watts - and output isn't much, if any, better than an RLp15.

Perhaps all that excursion capability is being used as a method to keep distortion low?

[SteveCallas]

I think I figured it out - it's the very high Bl. This article is interesting:

http://www.aes.org/sections/uk/meetings/0403.html

Notably:

Next vented systems were studied. The cone's acceleration is given by a combination of the box characteristics and the vent details. Vented box loudspeakers have extended bass, but it rolls off faster than a sealed box. When Bl in increased by 5times, the port resonance becomes almost undamped, generating a peak in the response at the resonance. This peak then requires a sharp notch filter EQ. This is not practical. Therefore high Bl drivers need a sealed box.

The Dayton HiFi 15" and Avalanche 18, both of which model extremely flat and go deep with a ported design, have a considerably lower Bl than the SS RLp15 and this TC Sounds 3000 15" (this TC Sounds driver's Bl is about 2x that of the HiFi and Avalanche). Apparently that works well with sealed implementations, but not so well with ported. That explains quite a bit for me, and probably why I have found the dual 4ohm RLp15 to model a bit better than the dual 2ohm in ported designs, as the dual 2ohm's Bl is a little higher.


EDIT: I agree with the suggestion of using the 2000 series, the single voice coil 15" to be exact. 300 liters and 600-800 watts per driver, tuned to ~15.7hz looks great, almost identical to an Avalanche 15 actually, just a tiny bit more sensitive.

[Mark Seaton]

Steve,

I would point out that it's not just a sealed box that needs/likes a high BL driver. If fact, if you have too much BL in a sealed box you start loosing LF sensitivity as you get more upper frequency output.

As a gross generalization, if you want to push the box size down while maintaining low frequency extension, higher Bl and higher mass drivers will work better. There are of course many exceptions. In the case of large, ported boxes, high BL isn't necessarily bad, but you certainly get to a point where it doesn't give you obvious gains in sensitivity. Further increasing BL does have some interesting effects on the impedance curve which impact current through the motor and thermal compression.

Also note that where I'm talking about increasing BL, that is only from the perspective of keeping Re the same. For different impedance drivers remember to figure BL^2/Re to get a force factor which you can compare.

The biggest problem I see with this driver is as Jack noted, HUGE inductance.

I do want to first commend TC for actually giving us the values for a good 3 part Le model. In this particular driver, depending a little on the alignment, I see about a 4dB hump from Le in the 50-55Hz range. Granted, this can be EQ'd back flat, but note that the response will start dropping above 70-80Hz.

Looking at just the drawings on the TC site, this looks to be a bigger evolution of the HE-15 type design with a hugely tall gap and somewhat longer coil. It does serve to give huge BL, which has it's applications, but the Le is large enough here to start impacting the entire frequency range, not just the top end. From what I'm seeing, you need something like a 2500W amp to make this driver put much of that 34mm Xmax to use in most desireable alignments. The most interesting alignment I came up with in a couple minutes was about 140L with 2 18" PRs at about 2500-3000g and 2000-2500W of power on tap. You would ideally want a 4th order high pass on that sort of system set to 13-14Hz. It's a good bit of output, but I think there are many more effective ways to do the same thing or better, with less expensive parts.

[Mark Seaton]

winisd pro auto-calculates Sd=830 cm^2...IF this is true then...5.64 liters Vd swept !!! 8O vs. 4.86 liters for a Tumult 15d2...incredible! :E

Don't believe everything you read on the internet... :roll:

I would be very surprised if the effective Sd is 830cm ^2. The parameters posted used 830cm^2 for all of the 15" drivers, and I'm all but certain that's well overstated for the TC-2000. Maybe Kyle could to some fact checking for us and determine what are some more realistic values. I would guess a range of 750-800 cm^2.

[DennisP]

Hmmm....great input guys, thanks very much. I take it then that this driver isn't the best choice for what I was hoping for (a low distortion, 2 driver, vented sub tuned reasonably low, without sacrificing high output in the upper bass frequencies).

So the TC-2000 is a better driver for a vented enclosure, but how does it compare to the SS (they are both TC designs, right?)

I may end up wanting to build a dual SS or a dual TC-2000 depending on how they compare.

-Dennis

[SteveCallas]

In the case of large, ported boxes, high BL isn't necessarily bad, but you certainly get to a point where it doesn't give you obvious gains in sensitivity

What I don't like is the ski slope FR and how that might interact with a normal room. And it seems that the higher the Bl, the less it wants to mate with a large enclosure (ported), so the low end capability and port noise (can't use a huge diameter port in a medium sized enclosure) take a hit.

What are the drawbacks to a lower Bl?

[SteveCallas]

So the TC-2000 is a better driver for a vented enclosure, but how does it compare to the SS (they are both TC designs, right?)

I may end up wanting to build a dual SS or a dual TC-2000 depending on how they compare.

Hmm, tweaked the 2000 15" SVC a bit more - 330 liters, ~14.8hz tuning, and 800 watts, and it outperforms my preferred RLp15 model in every way aside from excursion used, but that's why they give you more. Indeed, this 2000 15" SVC appears to be VERY similar to the discontinued Avalanche drivers.....they should make an 18"

[Scott Simonian]

.....they should make an 18"

You said it!

[kramskoi]

Don't believe everything you read on the internet... :roll:

I would be very surprised if the effective Sd is 830cm ^2. The parameters posted used 830cm^2 for all of the 15" drivers, and I'm all but certain that's well overstated for the TC-2000. Maybe Kyle could to some fact checking for us and determine what are some more realistic values. I would guess a range of 750-800 cm^2.

agreed!...but this was from no website, winisd pro auto-calculated this value for the tc3000...but that surely does'nt make it official...i've posted at tc-sounds for the "right stuff"... :T

[ThomasW]

The Sd used in the Unibox screenshot I posted was from the RL-p15". That should be pretty close to the 3000 unless they're doing the trick of using a portion of the surround...

[Jack Gilvey]

The difference between an Sd of 750cm^2 and one of 830cm^2 is about 1 dB.

[Mark Seaton]

Thomas,

In most cases the Sd ends up roughly equal to about 1/3rd the 1/2 roll. The 3000 & 2000 use entirely different surrounds. I only played with the 18" version of the tall profile surround, and that was a couple years back. 804 cm^2 sounds reasonable, if not slightly optimistic for the SS, and I would expect the 2000 to have the same Sd. I'm not sure on the 3000.

While the Sd shifts all of the parameters, it will first be seen to affect the sensitivity and output for a given excursion. It's not a huge difference, but worth noting, and can certainly make a driver look a bit different when comparing models that are already fairly close. As the drivers get heavier with higher excursion capabilities, I've seen more variations that simply don't make sense with simple logic of what the differnces are between two drivers. In other words, know that we're in the ballpark, but hardly dealing with pinpoint accuracy.

[Amphiprion]

Geometrically it makes sense for 1/3 of the surround to count towards Sd.

Mark, since you've played with the tall surround they're using, how does it compare to the 1/2 roll? More linear or just more maximum excursion allowed? Suckback issues etc?

[DennisP]

Hmmm...decisions decisions...

Steve, when you say 330 liters enclosure volume, that's for 2 drivers and 800W per driver, right?

-Dennis

[SteveCallas]

:twisted:

No, 330 liters and 800 watts per driver. To get that low end reach while maintaining high sensitivity, you gotta go big. Remember, my sub is 700 liters :B

EDIT: I just read my post and I guess if you don't know me it may come off as being sarcastic, so let me clarify. Yes, I am serious, 330 liters and 800 watts per driver.

[DennisP]

Don't worry my friend, I'm the sarcsasm king, so I got ya.

Dang, that's massive! I have to ask- is there a pair of drivers that can offer comparable output (and price) that can do it in a smaller enclosure?

But just for giggles- how big would the port need to be (diameter x length) for this hypothetical monster?

-Dennis

[SteveCallas]

For the 330 liter TC 2000 sub, I'm looking at a 7" diameter port that is ~36" long. As for a pair of drivers that can equal it in a smaller enclosure for around the same price, the only thing I can think of would be a pair of sealed Dayton HiFi 15" drivers in a sealed enclosure, but they would still come up short in terms of low end output.

330 liters isn't that bad - if you have to get it past your wife, show her a picture of my sub - she'll be thanking you for going 330 :T

[noah katz]

"When Bl in increased by 5times, the port resonance becomes almost undamped, generating a peak in the response at the resonance."

I don't understand this at all.

I thought higher BL meant lower Qe, which is higher damping. Or to say it a different way, the high back EMF should really give the driver a good grip on the port resonance.

Conversely, lower Qe in a sim program and watch the hump grow at Fb from too little damping.

"I'm looking at a 7" diameter port"

Here you go:

http://www.acoupower.com/products.php

Say Mark, I wonder if you noticed I PM'd you at AVS some days ago

[SteveCallas]

Far too expensive for my tastes, I'll stick to sonotube for ports and roundovers for flares :lol:

[DennisP]

Does this sound ok-

712L (prior to driver loading, bracing, stuffing, etc.)

Cabinet dims (I'm going to stand it vertical after all)

21"W x 30"D x 69"H inside dimensions

Assuming a doubled 3/4" cabinet (probably 2 layers of baltic birch), outside dimensions should be 24"W x 33"D x 72"H.

Is this enough to get to 660L after all the drivers, stuffing, bracing, etc.?

I'd like to mount the port on the top, but I assume it will be stinkin' huge- (12"D?)

-Dennis

[Mark Seaton]

I'd say don't bother with dual layer walls if you are building with Baltic Birch. Just use plenty of bracing. You will probably want a dual layer baffle just to recess the drivers. With a box that big, you could just glue in a backer board to recess where needed. Things to consider at least. 1.5" less in one dimension for something that large can make a BIG visual difference.

[noah katz]

"Assuming a doubled 3/4" cabinet ..."

I agree with Mark [that's living dangerously, huh? ] . That's a lot of unneccesary volume, weight, and $.

As I found with my dual Avalanche 18 sub, you can get an inert box by making sure that any panel has no more than about a foot between any two support points (perpendicular panel or cross brace).

[DennisP]

Okay, that just saved me a chunk of change on the box materials! Thanks guys!

What kind of material should I use for the bracing inside? 1/2" MDF? 3/4" MDF? Or go all baltic birch?

-Dennis

[steve nn]

Things to consider at least. 1.5" less in one dimension for something that large can make a BIG visual difference.

No doubt about it" The difference a few inches can make.. is really quite remarkable.

[steve nn]

What kind of material should I use for the bracing inside? 1/2" MDF? 3/4" MDF?

I would stay away from the 1/2". The 3/4 MDF would be the rout I would take myself, little heavier than the B though.

[SteveCallas]

Wow, this guys is serious folks.....first JonW, then steve nn, now DennisP - now I don't feel so crazy anymore

712 liters raw should come out pretty cose to 660 liters effective after the bracing and port. That sounds on the mark.

As for the port, a single 10" that is 34" long will do the trick, no worries about chuffing there.

Feed it with 1600 good clean watts and you should have all the capability you will ever need ~120db down to at least 15hz, potentially lower depending on your room gain. Very, very nice. I swear you guys will force me to assemble my second sonosub in this apartment...grumble :x

[steve nn]

Now just hold it here! I'm going to wind up being the runt in the neighborhood with 601 Liters Raw. I must seriously reassess this situation.

A word of caution Dennis, if you go with veneer, be sure to go with the 4 X 8' sheets instead of the 2 X 8' sheets. Welcome to the Brotherhood.

[Rene D]

[QUOTE=steve nn]Now just hold it here! I'm going to wind up being the runt in the neighborhood with 601 Liters Raw. I must seriously reassess this situation.

Don't feel too bad, Right now a 600 L or larger box is my bedroom closet and a good chunk of the bedroom itself!. Hmmmm *rubs chin* I Wonder if the wife would notice me boarding off the closet and two 15-18" drivers suddenly mounted in the living room wall?

you guys are turning out to be a VERY bad influence on me! :W

Rene D

[SteveCallas]

you guys are turning out to be a VERY bad influence on me!

Once you give in to legitimately thinking of a way of how you might be able to "make it work", it's all over - no sense it fighting it much longer :T

[DennisP]

Sweet! I'm going to start checking around for suppliers for both MDF and BB ply...are the big box stores worth checking? (Home Depot, Lowes, etc) Or should I look at smaller lumber/ wood suppliers to get specifically what I want?

Hmmm...not sure about the finishing yet, veneer would be nice, though I wouldn't mind staining the BB ply as an option.

I have a lot to learn every step of the way (from construction to finishing, then wiring, then my biggest worry- the proper eq'ing for my room), and I anticipate this will be a long process for me, but with help from the fine folks here at htguide, I should be able to achieve bass nirvana. I currently have a PC-Ultra in my setup, which was fantastic in my old HT setup before we moved to a new house, now it does ok, but my brother in law's PB/Ultra2 is obviously spanking the crap out of the single 12" in my cylinder. So, hearing that sub in action has inspired me to want more! :B The nice thing about all this is that I'm in no rush, but I do want to get started on the cabinet pretty soon, with many questions to follow.

-Dennis

[SteveCallas]

Lol, when this is done, your brother-in-law will be in disbelief - first at the size, then after you fire it up, the performance. Seriously, this will be a monster. If you wanted to save a few bucks and some size, you could go for a replica of Steve's and not really give up anything that I would say is going to be noticable (since you shouldn't come close to pushing this thing to its limits), assuming the two drivers don't have a completely different tonal quality. Just something to consider...but at the same time I'd like to hear some first hand impressions of these drivers Either way, you can't lose.

I wouldn't worry much about the EQ, you may not even need it. If you do, with RoomEQ Wizard, it should be a piece of cake.

[Amphiprion]

what speaker systems are you guys matching these monster subs up with

[SteveCallas]

Bose Lifestyle for me.

[steve nn]

Bose Lifestyle for me.

You to!? :lol: Man you sure have class br C..and I thought I was the only one that ran the cubes around here. :T

So, hearing that sub in action has inspired me to want more!

Well lets hope he doesn't come over and listen to yours after your finished. I can humbly tell you there will be a difference.

though I wouldn't mind staining the BB ply as an option.

From the pics I've seen so far, the BB ply comes out real nice and the edges with all the bands looks pretty attractive. It certainly would be a time saver and simplify the process.

[DennisP]

From the pics I've seen so far, the BB ply comes out real nice and the edges with all the bands looks pretty attractive. It certainly would be a time saver and simplify the process.

Yeah, I've seen some speaker projects that look pretty nice with stained BB ply. I might consider veneering though, your sub looks like a commercial unit to my eyes (meaning it looks professional!) ;x(

The other option to building this myself (or with some family help) is to hire a cabinet maker to build the box for me, perhaps even finish it. I have a feeling it wouldn't be cheap though. I'm in the San Francisco Bay area, if anyone knows of a good furniture/ speaker cabinet maker that won't totally rape me, I'd be willing to get some quotes.

I'm an architect by day, so I have great AutoCAD skills (and the full version of the software to draft in 2D or 3D if necessary). I can produce all of the dimensioned drawings for the cabinet, including bracing locations, etc. and hand it off to someone who knows what the heck they are doing and get the thing built for me. If that turns out to exceed the budget (which is still sketchy, just ask my wife... ) then I'll just go full force on the DIY box route.

-Dennis

[SteveCallas]

Dennis, if budget starts coming into play, as I mentioned earlier, you can use two RLp15s and a slightly smaller box (basically a clone of Steve's sub) and still get nearly identical performance. The TC Sounds driver outperforms the RLp15, but just barely so.