I had the need for a smaller powered sub for drum monitor,smaller rooms, and to loan,lend to friends.
I had 2 6.8 cubic foot sub boxes loaded with a fresh set of these.
Peavey 1808-8 CU BWX 18" Woofer Speaker Driver 294-307
I saw that QSC was blowing out the power amp module for their HPR151w subs. At first I was going to pick up 2 for spares for my HPR181i subs.
But after some testing it seems the low cut filters were higher and the limiters seem to be set sooner/longer time constant because they were designed for the smaller 15 inch woofer. I figured I'd put them in the unpowered boxes that I had and see how they worked. I would still have these available to replace a bad HPR181i sub amp while it was sent out for repair should that ever be needed.
The amp modules required their own chambers so I added those to the boxes. This brought them down to about 6.25 cubic feet. The box tuning changed to about 48hz. This worked out well as the steep lowcut filters on the amp seems to be set at about 50hz.
The boxes have a 6db down point at about 45hz and 6db down at 140hz as well. This is pretty much the same freq. response as the HPR151w boxes the amps were designed to go in. There is a 6db peak around 83hz. I'm unsure if this is eq voicing put in by qsc to give a givin' response in their box or a peak in my box/speaker/amp combo. You can see it in the smaart capture. This was a rough measurement in my home so I will take another look when weather permits outside.
QSC - HPR Series - HPR151W
Overall I'm happy with the boxes. The phase response is close enough that I can use them with an hpr181i sub if need be.
This turned out to be a low cost powered sub project that should work well for its intended use.
Douglas R. Allen
"I was unsure as to where was the correct place to post this so please move as needed"