View Full Version : help quick! tuning freq for idq8 in 2.1 setup

03-10-2007, 07:40 AM
Hey all.

I'm going to be adding an IDQ8 as a subwoofer into my two speaker bedroom setup. The speakers are the Acoustic Visions Kit 51 (

Right now the speakers look-a like this:
http://img183.imageshack.us/img183/757/dscf9523xq8.th.jpg (http://img183.imageshack.us/my.php?image=dscf9523xq8.jpg)

You can imagine the other speaker's location mirrored onto the other side of the TV stand.

Basically I want to build a subwoofer box that slides into that middle vertical section (out of 0.75" MDF) for an IDQ8.

Image Dynamics suggests one of the following for a ported design:

1 cuft, 2" inner diameter port 9" long; tuned to 28hz
0.5 cuft, 2" inner diameter port 10" long, tuned to 35hz
0.5 cuft, 2" inner diameter port 6.5" long, tuned to 45hz

Which one should I go with?

Any input appreciated and quick! I'm gonna start building this in about 2hrs (8:30am EST)


03-10-2007, 01:16 PM
For HT and music in a home setting I would say the 1cuft, 2"x9" tuned to 28hz.

Reason being you want to have it very low for HT and very flat for music. :fyi:

03-10-2007, 05:17 PM
Well - I started working on it at 9:00am (before your post) and I decided on doing the 0.5 cuft with 2"x9" port.

Firstly - there was a very noticeable amount of port noise. I assume that this would be fixed by flaring the edges, though. As a temporary fix, I took out the port (which was sealed in with rope caulk) and sealed up the hole by clamping a spare piece of MDF on there. Either way, the sub simply would not play at even relatively loud levels before clipping, detailed below:

I have some questions about the amplifier. it's the Dayton 500w amplifier from Parts Express (http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-806). The specs on the page say 540w RMS for 4ohms, 273w RMS for 8ohms, but the manual states that these are the MAX values, not RMS. I noticed that the speaker started clipping (And the clip indicator light on the amp lit) way before the sub got even barely loud. With the port in, the same was true, plus a lot of port noise. It was moving a lot of air.

Basically, 273w MAX should be at least 125w RMS, which would be enough to get the sub to play louder than it is.

Or maybe it's an IDQ8 which, for subwoofer applications, is a pure SQ sub, and I'm expecting way too much out of it.

Any input?