DIY Subwoofer Situation

[panteragstk]

Hey guys. I've currently got two infinity 1262w 12" drives with my Crown XLS1500 amp.

I didn't buy the right drivers so I'm using them in 8 ohm config which gives each driver 300w. I was using them in a 2 ohm config just to see and they were over-driven so I re-wired them to 8 and have been happy since.

I wanted to use all the power my amp has to offer so I got 3 1260w drivers (should have been 4, but the guy I got them from sold one before I got my order in).

My issue is I now have 5 drivers and I need to decide what to put in theater for the new house. I'm going to use 4 drivers no matter what. Thinking of 4 corner placement as that should provide the most even bass for my room setup.

Here are my choices:

1. Use two 1260w 4 ohm drivers and two 1262w 2/8 ohm drivers wired so the amp sees a 3ohm load. Not sure what wattage that would give me, but it should be around 355w per driver.
2. Find another 1260w somewhere and wire them to where the amp sees a 2 ohm load for about 387w per driver.

All drivers have an RMS of 350w so I shouldn't be much out of range if at all for either config. The reason I'm leaning toward option 1 is because it is spot on for wattage and will leave me with one extra driver to put in my office or something. What I don't know is what amount of wattage each driver will see. From what I know it won't matter that one driver is 4ohm and another is 2ohm they will both get the same wattage since they are essentially averaging out. Am I right?

If I go with option 2 I have 2 extra drivers that I don't really need, but would probably do something with. But that puts me 30w over the RMS of each driver. Shouldn't really do any damage, but I'm not sure.

What do you guys think?

 

[TLS Guy]

How to you have them wired exactly? You may have the impedance to come out, but I think you have the power distribution between the drivers way out of wack.

 

[panteragstk]

How to you have them wired exactly? You may have the impedance to come out, but I think you have the power distribution between the drivers way out of wack.

I was just going to wire the dual voice coil in the 1262w parallel so that at the plug in the box reads 2ohm with my meter. Then wire the 1260w (4 ohm) to the 1262w box (2 ohm) in parallel so that the amp sees the combined load of 3 ohms.

I too am afraid that the power distribution will be wrong, that's why I'm asking about this setup in hopes that someone has done this or at least can tell me how I can measure the power each driver is getting. Or at least come up with an educated guess. Right now all I have is the simple math of wiring in parallel.

This link seems to agree with my hopeful assumptions that if the load is 3 ohms the power will be evenly distributed to the drivers.

 

[lovinthehd]

What do you mean in 2ohms they were overdriven?

 

[TLS Guy]

That I suspected. You can not do that. When you wire speakers in parallel they MUST ALL be the same impedance, otherwise most of the power goes to the lowest impedance load.

There is no way to make this work, unless you use separate amps to each of the impedance loads.

 

[panteragstk]

That I suspected. You can not do that. When you wire speakers in parallel they MUST ALL be the same impedance, otherwise most of the power goes to the lowest impedance load.

There is no way to make this work, unless you use separate amps to each of the impedance loads.

That's what I was afraid of. Guess I'll be getting another 1260w from somewhere. Or I could just run two 1260w as the "front" and the 1262w set as the "back". Then I'd have one amp channel running at 4ohms and another running at 2ohms. That would get the 1262w set 325w each and the 1260w set 387w each. Should work just fine that way.

Thanks

 

[panteragstk]

What do you mean in 2ohms they were overdriven?

They were getting 775w each when their RMS is 350w each.

They sounded great, but the amplifier went into protection mode because it kept clipping. I've used that amp at that power level before and had no issues.

 

[lovinthehd]

They were getting 775w each when their RMS is 350w each.

They sounded great, but the amplifier went into protection mode because it kept clipping. I've used that amp at that power level before and had no issues.

I've never driven my 1500s into protection mode, but may end up trying after I finish my second 1262 sub which I'll be running in 2 ohm mode (built one of two boxes so far, very slow build ). What do you mean power level? You talking about where you had the gain set? How did you determine where to set gain?

 

[panteragstk]

I honestly tried the gain level in multiple positions and it didn't matter. The drivers were moving a whole lot more than they were really designed to and the amp would randomly clip. It really only happened in LFE intense scenes, but often enough that I didn't want to kill a driver.

At 300w I don't have the same impact/spl, but they still sound fantastic. I love the drivers. Shame they are so hard to find now. I only paid $60 each for them brand new.

 

[lovinthehd]

What box did you build for the 1262? I'm using sealed, a bit over 2cuft net. You started with a gain that set the subs up to match your system level, then had to turn the gain down to avoid clipping?

 

[panteragstk]

I went with 2 cu ft net. Works perfectly. With the amp seeing 8ohms I have the gain all the way up so the receiver can control the actual output level.

I couldn't leave them at 2 ohms because the amp would go into protection mode no matter what I had the gain set to.

 

[lovinthehd]

I went with 2 cu ft net. Works perfectly. With the amp seeing 8ohms I have the gain all the way up so the receiver can control the actual output level.

I couldn't leave them at 2 ohms because the amp would go into protection mode no matter what I had the gain set to.

Thanks, interesting, I'll have to keep that in mind. This with the preout from the Onkyo 809?

 

[panteragstk]

Thanks, interesting, I'll have to keep that in mind. This with the preout from the Onkyo 809?

Yup. Works very well, just wish I had more power...

 

[BoredSysAdmin]

Am I missing something obvious here? If 1262w are dual voice coil 4oh, wiring both coils in series should give you 8ohm but wiring two drives in parallel should bring it back down to 4ohm.

1260w are single 4ohm - if you find another 1260w you could have done same trick as above, but with drivers this time, maybe go with Jinjuku's dual firing 1260w box design he posted in his 1260w thread (look in DIY section)

 

[panteragstk]

Am I missing something obvious here? If 1262w are dual voice coil 4oh, wiring both coils in series should give you 8ohm but wiring two drives in parallel should bring it back down to 4ohm.
View attachment 19542

1260w are single 4ohm - if you find another 1260w you could have done same trick as above, but with drivers this time, maybe go with Jinjuku's dual firing 1260w box design he posted in his 1260w thread (look in DIY section)

You are correct. If I wire the 1262w I either get 8ohm or 2ohm at each driver. Then I can wire for a 4ohm load so that one channel of the amp is running at 4ohm and the other at 2ohm for the 1260w. That would give the 4ohm channel 525w (I misread my amp specs above) to split between the drivers and the 2ohm channel 775w to split. Should work until I can find another 1260w.

I've looked at jin's build for when I find another driver. I think the above should work just fine even though there is a bit of a wattage difference it should even out with a driver in each corner of the room.

 

[BoredSysAdmin]

you should be able to adjust the levels on front to amp to match output. use spl meter for that

 

[panteragstk]

you should be able to adjust the levels on front to amp to match output. use spl meter for that

Good point.