IB and LLT in one

[g75]

Hi guys, my new house is almost finished and now it's time to start planning/building the HT.The room is located in the basement and is about 6*10*2,7 (w*l*h) that is in meter. All walls, floor and ceiling is concrete.

The problem is i can't decide what to build a LLT or a IB, so i thought if it could be possible to build both of them in to the same box.

The plan is to build two large LLT's about 3m3 each with a plug for the port so it could be sealed off, this would then fulfill the requirement for a IB setup (10*Vas).
How does this sound to you? i mean is this sane or insane?

As drivers i am thinking of FI audios Q.18 Dual2

[Geoff St. Germain]

A ported sub in a volume of 10*Vas is going to be too large and you're going to get a resurgence in the output at the tuning frequency. Are you planning 3m^3 for each driver? What tuning frequency?

[SteveCallas]

Ilkka's testing and Rodny's measurements and subjective impressions go a pretty long way to show that the LLT is superior in performance to any sealed enclosure - I don't have to end that sentence with "in my opinion" anymore either I'd set it up as a proper LLT from the get go.

[g75]

The problem is that i only have experience from 'normal' sealed and vented boxes. And in my own opinion a sealed sounds better than a vented, now i do not know the changes in quality with bigger volumes thats why i would like to experiment with both types.

At the moment i thinking of building the left sub as a 600l LLT, and the right one as a IB. Then by listening decide what to do?

Geoff that is true i did a small error in my simulation i had a 3m^3 box each and the tuning set to 8Hz and the plot was from 10Hz up, so i missed the bump at 8Hz. I guess the optimal for a LLT would be around 600l for the Q.18

[thxgoon]

If you are going to build one of each for comparison's sake, make sure you position them in the same place in the room and recalibrate to remove all other variables. I for one would be interested in your findings.

[Chrisbee]

g75

You have PM.

Look up to the right under Private Messages.

Regards
Chrisbee

[SteveCallas]

Why do you want to tune it to 8hz?

[g75]

SteveCallas wrote:

Why do you want to tune it to 8hz?

I don't, it was a error i did with the simulation with the 3m^3 box. If i go for the 600l the tuning should be somewhere around 14Hz.

At the moment it looks like i will go for the solution with one LLT and one IB, and then see what design will be the winning one. I guess it's a bit of extra work but

[Sonnie]

It may be a little more work, but nothing wrong with trying both and seeing which will produce the better results. Rodny did it with his IB and SLLT, so can you. I do recommend that you use REW and take measurements of both so that we'll all have a another good comparison between IB and LLT. If you don't already own one... I also recommend the Galaxy CM-140 for the SPL meter to measure on down pretty low for better results... possibly a Volcraft SPL Meter in your area OR the Behringer ECM8000 with mic amp. Please keep us updated with your progress... pictures and notes...

[g75]

Sonnie wrote:

I do recommend that you use REW and take measurements of both so that we'll all have a another good comparison between IB and LLT. If you don't already own one... I also recommend the Galaxy CM-140 for the SPL meter to measure on down pretty low for better results... possibly a Volcraft SPL Meter in your area OR the Behringer ECM8000 with mic amp. Please keep us updated with your progress... pictures and notes...

It's been a time since i done any speaker building, so i am i bit outdated on the measurement tools, back in the days i used 'Speaker Workshop' with a Wallin jig and a DIY mic and amplifier.
I have moved two times since i last used the tools and now i can't find the mic or jig or anything, so i need some suggestions on what is recommended to do?
I am too lazy to build a new mic so i guess the Behringer ECM8000 is a good choice.
But what SW to use, or is the Speaker Workshop still a good choise?

And of course pictures and notes when there is anything worth to show.

[Sonnie]

For speaker box design modeling... check this thread.

For measuring your response after the speaker is finished... it's a no-brainer, get REW, it's free and right here at the Shack. See the BFD | REW Forum where you can get all the help you ever dreamed of for REW.

As far as mics are concerned... yeah, the ECM8000 and a mic amp (with phantom power), along with an SPL meter is all you need. We provide you with correction values for that mic. Or if you can find the equivalent of the Galaxy CM-140, which I believe is made my Voltcraft in your area, it's a good mic and SPL meter combined that might be a little less expensive than the separate mic, amp and SPL meter.