10-25 hz, is it necessary for HT or Music? - Page 11 - diyAudio
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Old 13th October 2007, 03:01 PM   #101
Daveis is offline Daveis  United States
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TC-2000 12", wonder if its suitable for LT?
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Old 13th October 2007, 03:18 PM   #102
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hm.... your question tells me that you did not even start to read & learn about LT....

The version which will bring you the lowest frustration impact and good results down to 20Hz is version 1.
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Old 13th October 2007, 03:40 PM   #103
Daveis is offline Daveis  United States
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Quote:
Originally posted by ChocoHolic
hm.... your question tells me that you did not even start to read & learn about LT....

The version which will bring you the lowest frustration impact and good results down to 20Hz is version 1.
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.

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Old 13th October 2007, 04:01 PM   #104
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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...).
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Old 13th October 2007, 04:41 PM   #105
Daveis is offline Daveis  United States
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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?
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Old 13th October 2007, 07:41 PM   #106
GM is offline GM  United States
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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
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Old 13th October 2007, 08:20 PM   #107
Daveis is offline Daveis  United States
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Quote:
Originally posted by GM
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.

GM
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 N/M 228.00
Sd (m^2) 0.0490
Lp (mH)
Ls (mH)
Rp Ω

Constants
c (m/s) 341.00
d (kg/m 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

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Old 13th October 2007, 09:11 PM   #108
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by Daveis
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.
Hi,
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.
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Old 14th October 2007, 04:51 PM   #109
GM is offline GM  United States
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Quote:
Originally posted by Daveis


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?

Bipolar pair? You mean orient the two drivers electrically in phase, but pointing 180-degrees apart.

If they were mounted on two faces of a square box at 90-degrees at least I'd spread the vibration along two axis.

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...?
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 ??
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Old 14th October 2007, 05:52 PM   #110
Daveis is offline Daveis  United States
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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)
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