GR Research Sub

[mdrake]

I built a GR Research sub with their passive radiator and I am not to happy with the sound. It sounds very roary and not very tight or articulate. I used to be a professional car audio installer for years and I am very familiar with subwoofers. Has anyone had this experience or any experience with the GR Research subwoofer?

Matt

 

[mdrake]

Better explanation of what I am hearing

The bass seems to have a rather long over hang on the bass notes and seems to exaggerate the bass notes. The woofer also losses control on fast passages. Does anyone have any experience with the GR sub?

Matt

 

[jaxvon]

What is your room like? Is it in a basement? Also, what is in the room furniture and treatment wise? Lastly, what are the dimensions of the room, and where is the subwoofer, in relation to the room and the speakers? I suspect an acoustical issue here.

 

[mdrake]

Thanks!

You know, I never thought of that. To many years in car audio I guess. The room is large about 14ft wide by 20 long with a large opening to the kitchen. The sub is near a glass sliding door and almost at the end of the long room. There are two couches and the sub is next to the smaller couch. facing into an opening about 12x 12 feet square and aiming at a brick fireplace. I am pushing it with a Dayton HPSA-1000 which is a rack mountable subwoofer amp that pumps out 500 watts at 8 ohms and 1000 watts at 4 ohms with a 12db per octave variable crossover. I will take it out of it's current spot and place it in the center of the room to see if sounds any different. I have NO experience with passive radiators and I build manly 1/8 or 1/16 wave ported enclosures for most of my subs or I use a Zobel Compensation Network on sealed subs but this is my first time with a passive radiator.

Thanks,
Matt

 

[annunaki]

If you have no experience with passive radiators, how did you design your current enclosure?

Typically passive radiator systems will function like a ported enclosure without the vent issues. However, there are things that need to be considered. If you have a 12" driver, you sould be using at least a 15" passive radiator or dual 12" passive radiators. The enclosure is tuned with the passive radiators by adding mass to the diaphragm(s) as well as the enclosure size.

Other than room acoustics issues it could be that the enclosure is tuned to too high of a frequency resulting in very boomy response like a higher tuned vented enclosure.

 

[j_garcia]

The enclosure plans are provided for this sub. Did you use the same dimensions given in Danny's plans? Have you done the mass loading of the passive radiator? This sub can essentially be "tuned" also by using more or less weight on the PR.

I had this sub in my house and have heard it in two other houses and never once would I call the sound loose or to have any overhang at all. You may want to run numbers on it to see what your room is doing to your response as mentioned.

 

[mdrake]

Thanks

I appreciate all the feedback!!! I used the design on Danny's website and double checked it in a couple of box design programs. I think it is a combination of room acoustics and the inherent design drawbacks of a passive radiator. That being that the motor of the woofer has not to only control of the drivers cone but that of the passive radiator as well. I have heard this is a BIG drawback but I wanted to see for myself how well a passive radiator would work and I am not a fan. I did mess around with sound damping foam and room placement as was able to fix most of the overhand but not all of it. (Thanks for that tip!!!) It is still not as tight sounding as my 1/8 or 1/4 wave base reflex boxes or a well built transmission line. Guess I will be building a new box.

 

[j_garcia]

PR designs get about half way between sealed and vented - the driver thinks the box is larger than it is but still doesn't quite yeild the same tightness that a true sealed design would. It does however seem to go lower than a comparable sealed design with less power and I found this sub to be rather impressive for what it costs to build (providing you build the enclosure of course), but it isn't up there with the best subs I've ever heard. Good luck.

 

[jaxvon]

You know, I never thought of that. To many years in car audio I guess. The room is large about 14ft wide by 20 long with a large opening to the kitchen. The sub is near a glass sliding door and almost at the end of the long room. There are two couches and the sub is next to the smaller couch. facing into an opening about 12x 12 feet square and aiming at a brick fireplace. I am pushing it with a Dayton HPSA-1000 which is a rack mountable subwoofer amp that pumps out 500 watts at 8 ohms and 1000 watts at 4 ohms with a 12db per octave variable crossover. I will take it out of it's current spot and place it in the center of the room to see if sounds any different. I have NO experience with passive radiators and I build manly 1/8 or 1/16 wave ported enclosures for most of my subs or I use a Zobel Compensation Network on sealed subs but this is my first time with a passive radiator.

Thanks,
Matt

Try placing the subwoofer in different places around the room. The center will not be the spot for it, but try moving it in and out from the wall, and also sliding it along each wall. Corner loading can increase apparent bass, but can also result in boomy bass from the bump in the response.