Infinity Reference 1260 - design questions

[ani_101]

Hi

I am interested in this particular design, and there seems to be a couple of designs out there - a sealed one and a ported one.

The sealed one is good for music and the ported one can be made flat to below 20Hz for home theater.

Sealed is 36 to 42 L and the ported is around 101 L

A couple of naive questions:
- do I need to build 4 of them, 2 sealed and 2 ported, and use them appropriately for music and HT
- Seal the ported ones for music (plug the port)?
- Have 4 sealed ones - would that get it close to 2 ported ones?
- Which amp - Crown XLS 1500 or Behringer 3000 DSP - they are priced similarly. Maybe I add a mini dsp to the crown (later on at added cost)

In the grand scheme of things, i can afford one amp and two subs would be optimum, but i can add later on. So how do we get the best of both worlds or do i keep the worlds separate???

[jinjuku]

The room you are in will be part of the equation. I am working with a member at AVS forum on doing a (we think a quad array) (two locations) in his 11000 Cubic Foot room. It's a large enough space that 8 drivers will do a very nice job in a sealed dual opposed box.

We will drive this with the Behringer iNuke 3000DSP fan modded. Each channel will have a dual stack. Even the dual sealed will work for HT. 105dB at 20Hz sealed isn't anything to sneeze at considering the price. There are better but the question is cost. This is a great budget build.

[ani_101]

The room you are in will be part of the equation.

My room isn't too big - 16 by 20 or so... hence 4 subs might be overkill, so 2 are preferred

We will drive this with the Behringer iNuke 3000DSP fan modded. Each channel will have a dual stack.

Are all the 8 drivers being driven by 1 3000DSP? Id so how are you configuring it? What do you mean by dual stack - 2 dual opposed subs on each channel? If so would the 3000 DSP have enough juice?

Thanks

[jinjuku]

Two properly placed will do a good job assuming you have standard height ceilings. The plan is two dual opposed subs on each channel. The iNuke 3000DSP will have enough for the configuration. We will wire for 1kw RMS per channel at 2 Ohm/Channel.

[fastbike1]

I think 101 is too big / unnecessary for vented. 65 liters net will give you F3/F10 26/21 Hz. Personally,, I think a good sub is a good sub. Meaning I don't buy the Music OR HT. It's really a matter of tuning. The right build will do both well. The issue is that it's difficult to get really low tunings from a sealed box, but I'm not one that thinks infrasonices are that important.

Hi

I am interested in this particular design, and there seems to be a couple of designs out there - a sealed one and a ported one.

The sealed one is good for music and the ported one can be made flat to below 20Hz for home theater.

Build two sealed ones and try them out. If you like it, finish the boxes. If you don't, build new bigger boxes.

Sealed is 36 to 42 L and the ported is around 101 L

A couple of naive questions:
- do I need to build 4 of them, 2 sealed and 2 ported, and use them appropriately for music and HT
- Seal the ported ones for music (plug the port)?
- Have 4 sealed ones - would that get it close to 2 ported ones?
- Which amp - Crown XLS 1500 or Behringer 3000 DSP - they are priced similarly. Maybe I add a mini dsp to the crown (later on at added cost)

In the grand scheme of things, i can afford one amp and two subs would be optimum, but i can add later on. So how do we get the best of both worlds or do i keep the worlds separate???

[ani_101]

so, now the question if i built a vented / ported sub say 65 or 101 liters and tune it low. Can i get the performance for music as offered by the sealed sub by plugging the port? How well the port needs to be plugged - can simply inserting convoluted foam in the port work? Also the ported, even at 65 l is double the volume of the sealed sub.

what happens to the power handling in sealed vs ported for the same sub?

[fastbike1]

I think you're worrying over minor actual listening differences.

The 36 liter sealed models w/ an F10 in the low 20s. In this case with 300 watts, F10 is still 97dB, i.e. plenty loud. The larger vented boxes don't give an F10 that is a lot lower, you get a lower F3 (which may not matter too much) and 3-4 more dB output, which also may not matter since you're well over 100dB w/ sealed.

so, now the question if i built a vented / ported sub say 65 or 101 liters and tune it low. Can i get the performance for music as offered by the sealed sub by plugging the port? How well the port needs to be plugged - can simply inserting convoluted foam in the port work? Also the ported, even at 65 l is double the volume of the sealed sub.

what happens to the power handling in sealed vs ported for the same sub?

[fbov]

Yes, minor differences, and it you tune low enough, there should be none!
http://www.hometheatershack.com/foru...explained.html

Interesting concept; tune so low that there's no port output in the "music" range so only driver response matters, but with prodgious infrasonic output should you send it those signals. Best of both worlds, if you have the space...

HAve fun,
Frank

[Mayhem13]

if this were my build, i'd use four of the 1262 2ohm models and build two sealed enclosures. Each enclosure would be 75L loaded with two drivers, on either side. Instead of screwing the drivers into the baffle of the dreaded T-Nuts, i'd use threaded rod passing through each drivers mounting points, helping to couple the drivers. The airspace created within the rods,i'd leave empty and heavily stuff the outerside areas.

On second thought, maybe i'll just do it for the family room and see how it goes. We need new end tables in there anyways.

[ani_101]

if this were my build, i'd use four of the 1262 2ohm models and build two sealed enclosures. Each enclosure would be 75L loaded with two drivers, on either side. Instead of screwing the drivers into the baffle of the dreaded T-Nuts, i'd use threaded rod passing through each drivers mounting points, helping to couple the drivers. The airspace created within the rods,i'd leave empty and heavily stuff the outerside areas.

On second thought, maybe i'll just do it for the family room and see how it goes. We need new end tables in there anyways.

Dat wud B awesome!

so let me get this - the two driver are i nthe same 75L box? No divider between them??? and you'd have threaded rods the entire length of the box, going from driver to driver!!!

[Mayhem13]

Yep...two 1262's wired in series model very well in 75l sealed sharing the same air space. The opposed firing makes the enclosure very stable and the partial coupling of the drivers using threaded rod reduces enclosure resonance significantly. Using an amp with on board DSP should yield near flat response to below 20hz at pretty intense levels....+100 db with two subs/4 drivers.

Using the threaded rod requires a bit of patience. I've used acorn nuts on both ends but you have to be sure that the Nita's threads don't bottom on either end or the drivers will have no torque load on the mounting ring. That's where the precision comes in....cutting the rod to the right length. I usually cap one side of each rod first using lock-tite and insert the rods through both drivers. Then add nuts to the opposing side and tighten in an alternating pattern. Usually it requires 2-3 passes to get everything even. Works extremely well and when you rap the baffles, sounds like knuckles on stone.

[ani_101]

Yep...two 1262's wired in series

Wired in Series, so they are firing in phase? I'd expect firing out of phase so both the cones are moving in the same directions...

Did i get this correct? opposed drivers at either end of the enclosure - facing outward, wired in series, cones moving in opposing directions?

[Mayhem13]

.......? Why the phase question. Same phase. Drivers move OUT at the same time and IN at the same time.

[fastbike1]

Mayhem's wiring insures that any rocking moment is cancelled. Note that 2 drivers in 75 liters = 1 driver in 36.

One point here is that it seems to be hard to go wrong with the 1260 / 1262. There have been several builds; single small sealed, single larger ported, double larger ported. All builds reported to have excellent results provided they have enough power.

Wired in Series, so they are firing in phase? I'd expect firing out of phase so both the cones are moving in the same directions...

Did i get this correct? opposed drivers at either end of the enclosure - facing outward, wired in series, cones moving in opposing directions?

[ani_101]

.......? Why the phase question. Same phase. Drivers move OUT at the same time and IN at the same time.

sorry, i was confused. In series would make the drivers move In at the same time and Out in the same time...

[fastbike1]

Interesting link and concept. Thanks for pointing it out.

Yes, minor differences, and it you tune low enough, there should be none!
http://www.hometheatershack.com/foru...explained.html

Interesting concept; tune so low that there's no port output in the "music" range so only driver response matters, but with prodgious infrasonic output should you send it those signals. Best of both worlds, if you have the space...

HAve fun,
Frank

[Mayhem13]

sorry, i was confused. In series would make the drivers move In at the same time and Out in the same time...

I think you still might be a bit confused. Series or parallel wiring doesn't inherently reverse the phase of either driver. In this case, it's used to sustain a suitable resistance ( load/impedance) that a typical subwoofer amplifier can handle safely and use efficiently. The 1260's I believe are nominal 4ohm drivers, and wiring a pair of these in parallel creates a 2ohm load.....very difficult to drive while wiring them in series produces an 8ohm load, easy to drive but halves the amplifier output current so overall efficiency suffers. I mention the 1262's as a nominal 2ohm unit where a series pair still maintain the rated 95db efficiency, increase output by 3db and maintain the ampl friendly 4ohm load.

[ani_101]

I think you still might be a bit confused. Series or parallel wiring doesn't inherently reverse the phase of either driver. In this case, it's used to sustain a suitable resistance ( load/impedance) that a typical subwoofer amplifier can handle safely and use efficiently. The 1260's I believe are nominal 4ohm drivers, and wiring a pair of these in parallel creates a 2ohm load.....very difficult to drive while wiring them in series produces an 8ohm load, easy to drive but halves the amplifier output current so overall efficiency suffers. I mention the 1262's as a nominal 2ohm unit where a series pair still maintain the rated 95db efficiency, increase output by 3db and maintain the ampl friendly 4ohm load.

Ah, i forgot these are DVC....!

[ani_101]

Where do you get threaded rods that span 2.6 ft, assuming the baffle is 1 sq ft. 75 l = 2.6 cu ft?

[jinjuku]

Probably Lowes or HD(?). I don't know if you need to go through that type of effort. I would simply have a brace that spanned between the baffles. Two so that would be one on either side of the woofer cutout.