[Danny Richie]

I have loaded the new sub-woofer info to our site and they can now be ordered from the web site.

http://www.gr-research.com/sub.htm

[Al Garay]

Hi Danny,

I know you have listened to Jeff's SCC300s. I realize there is personal bias. But can you describe how these two compare?

The thought of a small 2.5 cf enclosure is very appealing.  Though, I'm trying to stay with sealed and looks like the SW12a performs best in a ported or PR enclosure.

Thanks,

Al

[RAW]

I snece a shipping date getting closer

[DFaulds]

Al,

Actually, the SW12A should work quite nicely in a sealed enclosure.  Based on published T/S, expect Qtc of .7 in about 2 cu ft with an F3 in mid 30's.  With room gain, it should provide solid output below 30Hz.

[klh]

Danny:

For the subs, I have a few questions...

1. With the current PR enclosure design, how far from the front wall should the sub be positioned for optimal performance and what is the minimal distance it should be from the front wall?

2. If one wanted both the PR and the active driver facing forward, would  that be a problem?

3. What is the Q value for the current active sub/PR/enclosure?

4. What would be the optimal amount of power to feed each sub?

5. How low would the the F3 be if one had stereo subs, or even better yet two pairs? Also, would that change if they were placed in the center of the front and rear walls as opposed to the front corners? I ask that because I've read there is a more even frequency response across the room while still having good low frequency extension when positioned that way (centered front and back with the back 180' out of phase).

Thanks,

Krister

[Danny Richie]

1. With the current PR enclosure design, how far from the front wall should the sub be positioned for optimal performance and what is the minimal distance it should be from the front wall?

I have been using one with the PR facing the wall at an angle and it is working nicely.

2. If one wanted both the PR and the active driver facing forward, would that be a problem?

No problem.

3. What is the Q value for the current active sub/PR/enclosure?

Qtc values are for a sealed box designs not PR or port loaded enclosures.

4. What would be the optimal amount of power to feed each sub?

A 200 watt amp would be fine. A larger amp will be even better and allow more head room so long as you don't over drive it.

5. How low would the the F3 be if one had stereo subs, or even better yet two pairs?

The F3 for this design is about 20Hz. What your room gain or room response is depends on a lot of different factors.

Also, would that change if they were placed in the center of the front and rear walls as opposed to the front corners?

Where then are placed will alter the amount of gain or cancellation you get from running a pair.

Placing them close together will allow them to behave as one unit and will maximize total output.

Placing them in opposite corners will cause them to cancel one another at some frequencies.

[jjb]

Danny, Could the design be modified to be upright  with a downfiring Sub-W and the Pass-W to the side or top. also could the WxL be modified to about 12.5  down from 16.5, this would increase the height, yet achieve a better wife factor. Jim:?:

[RAW]

I am sure the suspension will have no problem with SAG.
On the cabinet size I just built a few 18" cubes out of 3/4" 18.5" out of 1" and 19" cubes out of 1.25" MDF all designed for Dannys subs.
Enough room for Amps,custom feet these still look sweet.
Small yet packa very large punch.

Al

[klh]

Danny,

Thanks for the quick, systematic and detailed answers.

Krister

[Danny Richie]

You can change the dimensions to just about any scale you want and you can fire the woofer down with no problem too.

But, the PR can not be fired up or down. It must be kept vertical.

[David Ellis]

Danny,

It looks like the surround material on your woofer is foam.  This seems like a smart idea.  I would like your thoughts to verify this matter.

Foam has always been and remains extremely well damped - much better than rubber.  Foam is also very compliant and will therefore offer better sensitivity.  From a mechanical standpoint, foam is a win-win surround material, eh.

From a longevity perspective, foam surrounds have a bad history.  Foam tends to rot.  The degree of rot depends on ambient climate and the chemistry in the foam.  I believe the chemistry of foam has improved, but only believe this via rumor.  The rumor-mill seems to agree the new foam surround materials will last 15-20+ years.  Do you have the inside story?

Dave Ellis

[Danny Richie]

Yea, it's foam.

Foam was chosen to increase the sensitivity.

To meet my goals of offering really low extension in a small box there had to be a sacrifice in some sensitivity already and a rubber type surround would have made it even lower.

I think this type of foam should last a long time and the quality of foam surrounds is better than it was twenty years ago.

Even still, in this day and age if a guy keeps a speaker for twenty years and still uses it then it lasted pretty well.

[Brian71]

So far, I've got 2 and am very pleased. Bass is fast and tight,  better than my previous M&K 5000.
http://pg.photos.yahoo.com/ph/brian.corr@sbcglobal.net/detail?.dir=3137&.src=ph&.dnm=ead0.jpg&.view=t

[David Ellis]

Yep, I figured foam was better than in years past.

[Red Dragon Audio]

Hi Danny,

It says on your site the PR needs to be mass loaded with washers and nuts.  Does it come properly loaded or do we need to add these things by ear?

Thanks!

[Danny Richie]

It has been pre-weighted so that it will give you an optimal tuning for an optimal box.

In the 2.4 cubic feet box it will tune it to 22Hz giving you an F3 of 20Hz.

I have been working with it in a new three way design stuffed into a 1.5 cubic feet box. Without altering it it tuned that small box to 26.5Hz giving me an F3 of 25.5Hz.



Most will never mess with it, but if you wanted to it is really easy to add or take away mass. This allows you to be able to tune it to whatever you want as per your application.

[jackman]

Hi Danny,
I have a 3.0 CU sealed box with an Apex Sr. amp and a Partsexpress Titanic II 12" woofer.  Although your woofer is probably much better, it's too late for me to change, and I'm too lazy.  Could I add your passive radiator go increase the output of my sub?  If so, could you weight it properly to work with my woofer and enclosure?

Thanks,
Jack

[Danny Richie]

Hi Jackman,

According to my numbers adding our PR to that woofer combo will increase your bottom end from being -10.5db down at 20Hz to being -5.7db down at 20Hz. At 30 Hz you're -5.1db down and the PR will bring you up to -1.3db down.

It should also increase the power handling too.

Certainly an improvement.

[Red Dragon Audio]

It has been pre-weighted so that it will give you an optimal tuning for an optimal box.

In the 2.4 cubic feet box it will tune it to 22Hz giving you an F3 of 20Hz.

I have been working with it in a new three way design stuffed into a 1.5 cubic feet box. Without altering it it tuned that small box to 26.5Hz giving me an F3 of 25.5Hz.

Most will never mess with it, but if you wanted to it is really easy to add or take away mass. This allows you to be able to tune it to whatever you want as per your application.

Danny my subs showed up today and they were packed very nicely.  They are built extremely well and  the pictures don't do them justice.  Massive construction that looks like it was well thought out and planned for sub bass indeed.  I am eager to start building away but I have some questions.

I want very tight, "musical", "tuneful", "articulate" bass.  Are those good enough adjectives of bass?  

1.  Will I be better off with a straight sealed design or should I go with the standard 2.4cuft passive radiator design?  I got the PR's so I could have the option.  

2.  If I weight the PR's more or less will that give me tighter bass or just change the FS/F3 of the enclosure?

3.  I want the low end extension that the PR route offers but will it fulfill all my bass desires?   :lol"

I am assuming it will be, but I have to ask.

Thanks for sending those out so quick.  12" subs are much bigger than I had remembered.  These bad boys are going to move mucho air I can feel it...or I will feel it.

[Danny Richie]

I want very tight, "musical", "tuneful", "articulate" bass. Are those good enough adjectives of bass?  

That sounds like the criteria I had when I designed these things.

1. Will I be better off with a straight sealed design or should I go with the standard 2.4cuft passive radiator design? I got the PR's so I could have the option.

Use the PR. It sounds great. I am very pleased with the combo and I am not easy to please or impress.

2. If I weight the PR's more or less will that give me tighter bass or just change the FS/F3 of the enclosure?

Adding or taking away mass will just change the tuning frequency and the roll off.

That thing has a lot of mass on it already so that you can get low tuning in a small box. Adding a little one way or another is a subtle change.

Think you can here the difference in tuning it from 22Hz (the way it is already) to changing it to 21Hz or 23Hz?

Don't worry about it for now. Just mount it and play it.

3. I want the low end extension that the PR route offers but will it fulfill all my bass desires? :lol"

You are using a pair of them in your room?

My guess is it will rock your foundations and grab you by the nads in a most pleasing way.  

Lets us know how it feels, will you?