ChocoHolic said:
Well, given that I have the TC-2000 in my possession already, I need constructive comments on what to do with them. If there's a particular posting or some driver specs that would make one better for LT, then I'd be happy to hear and learn. If there's a spec of the TC-2000 that makes it unsuitable then that's what I'm posting to a forum for in the first place.
But LT was going to be my last thought since I've got some experience with sealed and vented boxes.
I did not want to attack you. My comment was definitely meant constructive, because you are in the unfortunate situation that your mate is waiting for positive results from you. That's not a good situation to start learning the fundamentals and go through all pitfalls of something completely new.
I am in fact convinced that version 1 is a good solution as long as you do not need much lower than 20Hz. Only if you have a lot of signal content below that, then I would think about version 3. But most probable version 1 will serve your demands.
Also I do not see anything wrong with the driver (but I did not find the full spec on TC web page...).
I am in fact convinced that version 1 is a good solution as long as you do not need much lower than 20Hz. Only if you have a lot of signal content below that, then I would think about version 3. But most probable version 1 will serve your demands.
Also I do not see anything wrong with the driver (but I did not find the full spec on TC web page...).
The very large box, low tuning was what I was thinking.
My buddy is convinced that his current MK subwoofer is wonderful above 30-40 hz. He wants the new sub to be a sub sub covering the 15-35 range where his current sub is deficient.
I think he will change his mind about using his sub when he hears the TC sounds. But for now, I am going to assume that this is going to augment the lower end. That of course creates more problems because I need a relatively steep crossover to prevent from stepping on his current sub.
I have a Behringer DCX2496 that I could use and will probably let him have it to accomplish the blending of his current sub and the new one.
I'll also probably get a Dayton plate amp from PartsExpress to power it.
Is the blending of two subs going to work at all? Could you have one covering 20-40hz and another from 40hz to 80hz?
My buddy is convinced that his current MK subwoofer is wonderful above 30-40 hz. He wants the new sub to be a sub sub covering the 15-35 range where his current sub is deficient.
I think he will change his mind about using his sub when he hears the TC sounds. But for now, I am going to assume that this is going to augment the lower end. That of course creates more problems because I need a relatively steep crossover to prevent from stepping on his current sub.
I have a Behringer DCX2496 that I could use and will probably let him have it to accomplish the blending of his current sub and the new one.
I'll also probably get a Dayton plate amp from PartsExpress to power it.
Is the blending of two subs going to work at all? Could you have one covering 20-40hz and another from 40hz to 80hz?
GM
Well, ideally you want a band-pass and the TC2k needs to be mass loaded to lower its Fs to ~10 Hz to get the desired ~15-35 Hz BW and the full 2.5 kW to realize its potential, but the vent requirement due to its tiny Vas, low Fb dictates a large, massive passive radiator (PR) and preferably a bipolar pair to ~cancel out any excessive vibration. That said, a well damped vent works fine IMO if there's enough space available.
For a wider BW, then an EBS alignment of ~Vb = Vas, ~Fb = 0.707*Fs looks good with the PR caveat, so a ~Fs tuned TL seems a 'no-brainer' to me and EQ it ~flat in-room, though as always YMMV.
As for how well these would integrate with an existing sub system, it depends on the XO point(s)/slope(s) and where they're placed in the room referenced to each other and the mains, but in general, 40 Hz is so far down our hearing acuity curve that the room will completely dominate and it's been my experience that all folks typically notice is an increased sense of modulated pressure when a true sub kicks in assuming no extraneous higher frequency noises cranking up due to stuff rattling and/or audible modulation of the mains or possibly even the other subs.
GM
Well, ideally you want a band-pass and the TC2k needs to be mass loaded to lower its Fs to ~10 Hz to get the desired ~15-35 Hz BW and the full 2.5 kW to realize its potential, but the vent requirement due to its tiny Vas, low Fb dictates a large, massive passive radiator (PR) and preferably a bipolar pair to ~cancel out any excessive vibration. That said, a well damped vent works fine IMO if there's enough space available.
For a wider BW, then an EBS alignment of ~Vb = Vas, ~Fb = 0.707*Fs looks good with the PR caveat, so a ~Fs tuned TL seems a 'no-brainer' to me and EQ it ~flat in-room, though as always YMMV.
As for how well these would integrate with an existing sub system, it depends on the XO point(s)/slope(s) and where they're placed in the room referenced to each other and the mains, but in general, 40 Hz is so far down our hearing acuity curve that the room will completely dominate and it's been my experience that all folks typically notice is an increased sense of modulated pressure when a true sub kicks in assuming no extraneous higher frequency noises cranking up due to stuff rattling and/or audible modulation of the mains or possibly even the other subs.
GM
GM said:
How do you add mass to a driver to lower Fs? Can that be done in a way that wouldn't permanently mar the driver? I guess I wouldnt trust myself to do that correctly.
Bipolar pair? You mean orient the two drivers electrically in phase, but pointing 180-degrees apart. Yes, I'm afraid of the vibrations/stress on the box from the TC-2000. I ordered them not fully realizing that these drivers don't seem to be about finesse, but raw motor/power. I expect they will shake the box in ways I've never seen. If they were mounted on two faces of a square box at 90-degrees at least I'd spread the vibration along two axis. I don't know if there is any wisdom in that. I'm just thinking that if the box was in a corner having two drivers pointing in different directions might give a useful semi-omni directional dispersion.
Which alignment EBS or "~Fs tuned TL" will give more output under 25hz?
For the TC-2000 can someone help me determine, Vb that I will need to make this happen...?
Fixed SVC 12"
Qms 3.72
Res Ω 3.12
BL (Tm) 17.20
Mms (grams) 265.00
Cms µN/M 228.00
Sd (m^2) 0.0490
Lp (mH)
Ls (mH)
Rp Ω
Constants
c (m/s) 341.00
d (kg/m³ 1.20
K 9.64E-10
Calculated
Vas (liters) 76.39
Fs (Hz) 20.48
Qes 0.360
Qts 0.328
n0 1.76E-03
SPL (dB) 84.45
Hi,Daveis said:
I planished some strips of 16g sheet lead until about 0.01inch thick (0.25mm) and stuck them to the back of the cone with double sided tape.
I rechecked Q and Fs at each 20gms increment and used WINisd to model the effects.
I have no idea how long the tape will remain sticky, but the solution (adding 120gms) works well at the moment.
Daveis said:
A number of ways, though with the exception of small amounts of poster putty on smaller drivers, all the one's I've used were permanent.
Well, I was referring to dual passive radiators, but it works fine with drivers wired in phase also.
Yes, putting them 90 deg apart will help a little. Anyway, at sub/LF frequencies they are omni in all but the largest typical HIFI rooms, so there's no advantage from that POV. If you do have two drivers, then all things considered, an EQ'd bipole sealed cab seems a good choice.
Depending on the type/size of TL and amount of stuffing used to smooth them out in-room it's hard to say, but typically the TL will outperform the EBS overall, but can be 10+x larger as the trade-off, so what are the size constraints?
Make which 'happen'? The EBS, TL, EQ'd sealed, or ??
The room is 20x15 feet. I am guessing he wouldn't want anything larger than 12 cu feet.
I don't have the skills to do a complex TL inside the box. And the furniture makers I've talked to would have a hard time with it because they typically haven't built speakers for people.
An EBS is going to be easier for me to build (or have built).
How big would the TL need to be? (I can discuss the tradeoffs to him. Heck I might have him join diyaudio community so we can make it more of a team project than just me)
I don't have the skills to do a complex TL inside the box. And the furniture makers I've talked to would have a hard time with it because they typically haven't built speakers for people.
An EBS is going to be easier for me to build (or have built).
How big would the TL need to be? (I can discuss the tradeoffs to him. Heck I might have him join diyaudio community so we can make it more of a team project than just me)
OK, so slightly smaller than mine, but still decent sized with the on-set of room gain not beginning in earnest till < ~28 Hz.
Again, unless you use a PR for the vent in the EBS, it will be large/long, so will require one or more foldings of its own depending on how you configure the basic box. IOW for a MLTL the vent length can be reduced in length while yielding better broadband damping with less stuffing Vs a typical golden or acoustic ratio one:
MLTL:
L = 79.345"
WxD = 58.758"^2
zdriver = 24.496"
zport = near/at the bottom
dport = 5"
Lport = 55"
stuffing density = 0.2 lbs/ft^3
GR cab:
L = 27.03"
WxD = 172.478"^2
zdriver = 12.497"
zport = near/at the bottom
dport = 5"
Lport = 65"
stuffing density = 0.3 lbs/ft^3
All dims i.d. and can be rounded off to suit. Note that the vent diameter assumes that between any room gain and probably a fairly low signal level down around/at Fb that it doesn't have to handle high power levels, otherwise either it will have to be damped to attenuate any 'singing along', reducing output, or a larger/longer vent in the 7" dia./105" long range will have to be designed in.
The largest TL I calc'd was a BIB pipe horn at ~13.5 ft^3 net.
Again, unless you use a PR for the vent in the EBS, it will be large/long, so will require one or more foldings of its own depending on how you configure the basic box. IOW for a MLTL the vent length can be reduced in length while yielding better broadband damping with less stuffing Vs a typical golden or acoustic ratio one:
MLTL:
L = 79.345"
WxD = 58.758"^2
zdriver = 24.496"
zport = near/at the bottom
dport = 5"
Lport = 55"
stuffing density = 0.2 lbs/ft^3
GR cab:
L = 27.03"
WxD = 172.478"^2
zdriver = 12.497"
zport = near/at the bottom
dport = 5"
Lport = 65"
stuffing density = 0.3 lbs/ft^3
All dims i.d. and can be rounded off to suit. Note that the vent diameter assumes that between any room gain and probably a fairly low signal level down around/at Fb that it doesn't have to handle high power levels, otherwise either it will have to be damped to attenuate any 'singing along', reducing output, or a larger/longer vent in the 7" dia./105" long range will have to be designed in.
The largest TL I calc'd was a BIB pipe horn at ~13.5 ft^3 net.
When the vents are long like that what do you make the vent out of ?
You don't use PVC pipe for vents that long do you?
Would it make sense to build a rectangular vent into the box?
I'm concerned that a length of pipe that long with ring loudly even with the stuffing.
Also in the MLTL case with "WxD = 58.758"^2" that means the cross section of the pipe is smaller than the cross section of my 12" drivers?
What's GR stand for?
In a MLTL you are mass loading the driver or the column of air the driver is pushing?
You don't use PVC pipe for vents that long do you?
Would it make sense to build a rectangular vent into the box?
I'm concerned that a length of pipe that long with ring loudly even with the stuffing.
Also in the MLTL case with "WxD = 58.758"^2" that means the cross section of the pipe is smaller than the cross section of my 12" drivers?
What's GR stand for?
In a MLTL you are mass loading the driver or the column of air the driver is pushing?
Wood, you fold it up at the bottom or wrap it around the cab, whatever you want. The more bends and the higher its aspect ratio, the better damped it is. Stuffing can damp it till it has a better than sealed response, i.e. aperiodic.
Right, this driver has such a low Vas that when you divide the length into the optimum Vb there's not much left to work with.
GR = golden ratio as in the L x W x D = ~1.618:1.000:0.618
The driver energizes the cab's 1/4 pipe resonances which in turn mass loads the vent's 1/2 WL resonances and why for a given cross sectional area (CSA) will be shorter than in a typical cube or rectangular cab that has an air mass with a ~uniform particle density.
Right, this driver has such a low Vas that when you divide the length into the optimum Vb there's not much left to work with.
GR = golden ratio as in the L x W x D = ~1.618:1.000:0.618
The driver energizes the cab's 1/4 pipe resonances which in turn mass loads the vent's 1/2 WL resonances and why for a given cross sectional area (CSA) will be shorter than in a typical cube or rectangular cab that has an air mass with a ~uniform particle density.
GM said:
What would my expected F3 be in either of these cases? Which would sound better?
What is the Vb for the above or does that depend on how many twists and turns you give your port length?
I didn't realize the Golden Ratio had any acoustic implications. Apparently, it not only looks appealing, but has good acoustic properties?
Don't have a clue since it will depend on the room and where you place it, but simmed half space F3 = ~40 Hz with either cab.
XO'd at 35-40 Hz and a typical 4th order slope I doubt you could tell a difference due to the room's effect, though at 80 Hz the MLTL should in theory sound a bit 'tighter', but even that can probably be nulled out with stuffing.
Both cabs have the same Vb, so how you fold the vent will determine the added Vb, though the MLTL's shorter vent will in theory make it slightly smaller overall.
Yes, golden or acoustic ratios average out the internal eigenmodes (standing waves) to mimic the 'ideal' ~uniform particle density model, though with subs the cabs have to be pretty big for it to matter. Where the cab's modes are in the driver's BW though, it can make a big difference in how much stuffing is required, so while a cube is usually fine for a sub, not a good plan for a mid or 'full-range' driver, unless it's a B@$# of course!
XO'd at 35-40 Hz and a typical 4th order slope I doubt you could tell a difference due to the room's effect, though at 80 Hz the MLTL should in theory sound a bit 'tighter', but even that can probably be nulled out with stuffing.
Both cabs have the same Vb, so how you fold the vent will determine the added Vb, though the MLTL's shorter vent will in theory make it slightly smaller overall.
Yes, golden or acoustic ratios average out the internal eigenmodes (standing waves) to mimic the 'ideal' ~uniform particle density model, though with subs the cabs have to be pretty big for it to matter. Where the cab's modes are in the driver's BW though, it can make a big difference in how much stuffing is required, so while a cube is usually fine for a sub, not a good plan for a mid or 'full-range' driver, unless it's a B@$# of course!
Attachments
??? So? How much output do they have below 30-40 Hz where these two cab alignments are optimized for? I mean if you XO these two at 40 Hz, the half space F3 is around 12 Hz, but these numbers have little/no relevance since the room will boost/alter any speaker's response below 100 - 300 Hz depending on a number of variables. Not to mention that at rated power the TC2k will probably drown out the other two in their optimized BW, so by adjusting the sub's signal gain you should have no problem getting an in-room level match.