[Ron]

  I have built quite a few GR Research speaker systems over the past few years, but not the 12" servo subwoofer. From all that I have read it is appears to be a very clean, accurate, and musical sounding subwoofer. My question is how well does this servo subwoofer perform in a home theater type system? I know that some subwoofer that sound great for music listening may not sound as good for home theater use. I might be building one soon, but concerned that it may not have enough impact compared to a good vented type subwoofer in a home theater system  Any comments you may have regarding my question will be appreciated

Ron

[Early B.]

Ron --

I have not attempted to use my GR Research servo sub for HT. I have a separate 15" DIY sub for HT. The main reason I haven't considered using the servo sub for HT is because the goals of a subwoofer for HT and music are entirely different. For music, I want my sub to have clarity, finesse, detail, tightness, etc. For HT, I want the room to shake, some boominess, explosiveness, loudness, etc. I don't want my HT sub to sound like a musical sub, or vice versa. Of course, the servo sub will work fine for HT duty, but it won't be ideal, IMO.   

[Danny Richie]

  I have built quite a few GR Research speaker systems over the past few years, but not the 12" servo subwoofer. From all that I have read it is appears to be a very clean, accurate, and musical sounding subwoofer. My question is how well does this servo subwoofer perform in a home theater type system? I know that some subwoofer that sound great for music listening may not sound as good for home theater use. I might be building one soon, but concerned that it may not have enough impact compared to a good vented type subwoofer in a home theater system  Any comments you may have regarding my question will be appreciated

Ron

Ron, it will perform equally well in the HT application. Output levels will be similar to any other 12" sub with similar X-Max. And that same level of refinement and quality can be brought into that application.

[Ron]

  That is what I was thinking too that the servo sub is probably best for music listening, not HT use. Since I will be building the subwoofer for someone else, I will probably build them  a vented type subwoofer with a lot of impact in the low  end for movie special effects. Thanks for your comments.

Ron

[Ron]

  Guess I need to reconsider the 12" servo sub. The transient attack would definitely be a lot faster and lower distortion than a vented type sub. Thanks Danny for your comments.

Ron

[Danny Richie]

  That is what I was thinking too that the servo sub is probably best for music listening, not HT use. Since I will be building the subwoofer for someone else, I will probably build them  a vented type subwoofer with a lot of impact in the low  end for movie special effects. Thanks for your comments.

Ron

Porting it, or porting any sub doesn't give it more output over the servo sub. And the servo sub will be more linear right down to the rock bottom.

Output really comes down to the amount of air it can sweep.

However, a lot of heavy uncontrolled woofers have overshoot because of the stored energy. Like a woofer being put into motion with a driving force and then after the force is removed it continues on from inertia. The servo sub doesn't. So a typical woofer may be driven to 3/4 of it's X-Max but inertia takes it to full X-Max. The last 1/4 of its travel is uncontrolled. The servo sub is capable of playing to full X-Max under power. So even given the same sweep area the servo sub can be slightly louder because it can use the full X-Max under control.

[mlundy57]

Ron,

I have the sealed 12" servo sub in my main system paired with my N3's. The only difference is my unit has the Rythmik metal cone driver instead of the paper cone GR driver (next one will have the GR driver).

I'm not the biggest bass head for sure but the sealed 12" servo sub has plenty of output. The volume on the sub is set at the half way point and the sub setting in the AVR is -4dB.  With these settings the sub is not operating anywhere near it's max output and the bass is enough to be felt throughout the house. If I turn it any louder, my wife starts complaining.

Initially, I had the sub against the middle of the front wall and got plenty of punch for HT. However, I had to move it when I set up the N3s. Now the sub is behind the couch and in this position not only do I get punchy rumbly base, but the couch now shakes so much with the big explosions that it feels like I attached a tactile transducer to it (it shook before but not like this).  In all fairness to true bass heads and in the interest of full disclosure, the single sealed 12" servo sub doesn't rattle the windows out of their frames or shake paintings off the walls but then I wouldn't want it to.

The sealed sub is smaller than a ported sub would be and low frequency extension is not limited by the tuning frequency of the port.

Bottom line, the 12" sealed servo sub has more than enough punch for HT and finesse for music. Besides, a lot of movies have some very nice musical scores.

With the servo subs you really can get the best of both worlds.

Mike

[corndog71]

The 12" sealed servo sub is a monster! 

The previous sub I owned was a $700 B&W sub and even with its fancy dimpled port and 12" driver it ended up being rather boomy and had little definition.  This was probably due to its anemic 120 watt amp.

As one who likes to explore alternative ideas I built my sub as a cylinder.  My first speaker build!  I had a bunch of ideas for finishing it but the consensus was that I should leave it unfinished so you can see the 39 layers of MDF used to build it.  I was hoping it would be fairly dead but it still has a little resonance to it since I chose not to use any internal bracing.   I kinda wish I had one of Ruben's beautiful and much better braced enclosures.

The first time I hooked it up I got almost no output.  I thought something was seriously off because the output was barely audible.  But I let it burn in and and hour later it was producing some really impressive bass.  Still, not as good as I was expecting but I continued to burn it in.  After another 30-45 minutes or so I checked it again and it felt like the walls were going to come down!  I played the title scene from Serenity and as the ship enters the atmosphere the whole room rumbles and rattles and it sounds like you're there on the ship!  One 12" doesn't quite kick you in the chest so if that's what you want then multiple subs would be the way to go.  Still, the output on just one does a fantastic job.

It works well for music too.  I was listening to the Mission Impossible 2 score and there's one track where I was able to discern several different sized drums way in the back of the mix whereas before I could barely hear them and they all sounded the same.

[Early B.]

Ron -- are you considering an open baffle servo sub?

Just to clarify -- my comments above were related to an open baffle servo sub. A servo sub in a traditional box should be great for HT. 

[Ron]

Early B. - The sub I was considering would be a sealed type, not the open baffle.
 I appreciate every ones comments and input regarding my original question about the sealed servo subs. Looks like the servo subs are the best way to go for both music listening and HT use.

Ron

[bdp24]

  That is what I was thinking too that the servo sub is probably best for music listening, not HT use. Since I will be building the subwoofer for someone else, I will probably build them  a vented type subwoofer with a lot of impact in the low  end for movie special effects. Thanks for your comments.

Ron

Ron---No one has mentioned it (maybe out of respect for Danny), but Rythmik has plans on the website for a vented cabinet to put the 15" Servo driver in.

[Ron]

   The size of the room that the subwoofer would be used in is fairly small. I think a 12" sub in a sealed type cabinet would be the best choice. A 15" vented subwoofer would be just too overpowering. Appreciate the information about the Rythmik 15" vented subwoofer design.

[bdp24]

Ron---The reason I mentioned the 15" is because you said you wanted to make a vented sub. Well, Brian at Rythmik does not recommend his 12" for that application, and does not provide enclosure plans for it.

[Scott Trebble]

Ron, ...  I just finished a box (almost) for the 12" GR sub and Rythmic plate amp ...  just awaiting the parts from Danny.   I'm hoping for delivery late this week or next (I'm in Canada).
I based the design from one of Rueben's creations (thanks Rueben  )  The unfinished grill will just be regular black speaker cloth once I get the magnets installed and frame dyed.
  The main use will be HT, but music is important as well.  It will be paired with my new A/V-3 setup.
I'll be happy to report when things are hooked up 
Cheers,  Scott

[ebag4]

Very nice Scott, I like the black finish you used, can you tell us what type of finish (matte?) it is and how you applied it?

Best,
Ed

[Scott Trebble]

Don't want to hijack the thread.
Since this sub won't really be seen,  I just used a couple rattle cans of espresso (dark brown) satin. Nothin' fancy 

[Ron]

 Scott -  Your new 12" Servo sub cabinet looks great!  Nice job.  It should work really well with your A/V-3 setup. Thanks for posting the picture.

Ron

[Architect7]

Decide on a sub yet? I have a Rythmik FV15HP that I also use for music with one of the two ports stuffed.  It does not sound like a 15, very "fast" and easily keeps up with the transient attack of my line arrays.

With both ports open for movies it is an absolute monster.  In a 500sq ft room I have it dialed wayyyyyy down and some scenes on Inception still scare me with it.  I will only get rid of it if I have funds to replace it with two

[Ron]

  The subwoofer that I will be building is for my son. He recently had a house fire and everything in his home, including his HT system, was declared a loss so I will be building him an all new speaker system too along with the subwoofer. He doesn't want a subwoofer cabinet larger than 2.0 cu-ft. Even though the Rythmik FV15SE is an
excellent subwoofer, I think the GR Research 12" servo controlled subwoofer would be the best choice for his den area.  Since it will be about three more months before his home restoration work is completed, he has some time to decide, but I think he definitely wants to go with the 12" Servo sub.
Thanks for your input.