[cody69]

I just completed a pair of subs using Danny's servo drivers and the A370PEQ amp. This was the second pair of GR subs I've built, the first pair were based on the SW-12/PR-12 drivers, which proceeded the servo units. I've really enjoyed the SW/PR subs, so when I needed a second set for my listening room, I was eager to try out the newer servo drivers.

Here are a few pictures during construction. I followed Danny's plans, with a minor adjustment to recess the grills for a flush fit. I also followed the recommendation on this forum to use floor tiles to line the enclosure.









Once I get them broken in, I'll set up a side by side comparison between the servo and SW/PR subs. My initial reaction is the servo drivers offer a much tighter bass than my traditional subs, with no lingering decay of a bass note. However, they don't play as loud as the SW/PR subs, I have the servo amp turned up to 80%, while the traditional sub is set to 50%. This may change once they're fully broken in.

I really like these subs and plan to move these into my main listening room. And since the enclosures have a smaller footprint than the SW/PR units, the spouse will be pleased.

[Ron]

Wow! Your new Servo Subs look absolutely beautiful. Great cabinet work. Excellent job.

[corndog71]

Oh yeah, they take a while to break in. 

Those look terrific.  But "floor tiles?"

[S Clark]

Heavy linoleum floor tiles is the "poor man's" way to the added a mass layer similar to Black hole 5, whispermat, and No rez.  The carpet padding is an open foam deadener that can be bought in different densities. 

[motosapien]

Lovely craftsmanship there.   

[Danny Richie]

The difference in loudness is likely due to a difference in input sensitivity of the servo amp. So the setting on the volume control is not a real reference as to how high it is turned up.

They sure do look good too. 

[Plaid Frog]

are you running both subs off of one amp?

[cody69]

Yes, both subs (SW-12-08s) are being driven from one A370PEQ amp.

[Plaid Frog]

I am thinking about doing the same thing.  How far apart are you going to place the subs?  Is there a limit to how long the speaker wire from the subs to the amp can be?

[cody69]

I got different views on allowable distance between servo subs depending on who I spoke. I'll tell you what I learned and what I'm doing now -- hopefully Danny and others will chime in.

Currently my subs are about 6 feet apart.

Originally I was going to build the amp in one of the sub enclosures and run wire to the other one. But Danny told me there could be a problem with unequal lengths of the servo cables.

When I spoke with Brian at Rythmik, he was not concerned about the length of cable to the sub, but cautioned the subs should not be separated and should be together, preferably in same enclosure. He did say his concern was more theoretical, and hand not done any practical experiments with distance though.

I really wanted the subs spaced apart, so I built a separate enclosure for the amp and located it in between the two subs. This way I have equal cable runs to each and each sub enclosure is identical in volume, just in case that could cause a problem with the servo units.

I also ran fairly large cable out to each sub -- Belden 10AWG to the drivers and 12AWG for servo signal.

[Christof]

I like.  Ash?

[Plaid Frog]

That answers my questions.  I would be interested to hear what distance you settle on.  I am thinking of building a pair and spacing them 4-5 feet apart.  One on either side of my HT equipment stand.  Next question for you or anyone else, how would a pair of servo subs do for exclusive Home Theater use? 

[cody69]

Christof - yes, ash. Originally planned on using quartersawn veneer but decided to use flatsawn when I added the face frames since I thought it matched better and I had some pieces on hand wide enough to cover the sides without joining.

Plaid Frog - Like you, I have mine on each side of my equipment stand. I tried them side by side with short cable runs and could hear no difference from how I have them now, roughly six feet apart.

I have not used mine yet for HT, but will be bringing them into my main room next weekend, so I can post my impression then. You may want to consider upgrading to the 600watt amp as it may pack more punch for HT use -- talk to Danny and he can help you decide.

[drphoto]

Nicely done.  I really like the curved front pieces.

So what did you do w/ the plate amp? Mine is just in the cardboard box, which is a bit embarrassing. (I'm running the OB version) Did you build an enclosure for it?

You might want to play around with adding your old subs into the mix. They don't have to be at the same volume, just in different locations. Not more bass, but just smoothing out the room interactions. (The distributed sub theory) You may not have the space to keep it, but it would be interesting to try and see if you think it works just as an experiment.

[cody69]

Funny you ask... my amp was also sitting in the box for a bit  . Somewhere I saw a picture of a nice enclosure someone made, but I wasn't able to find it. So, I just made a simple box, cut out an opening for the amp and let in the speakon connectors in the top.







You have an interesting idea about co-mingling the old subs, I hadn't thought of that. In thinking how I would do this, I'm currently running a pair of subwoofer interconnects from the pre-amp L/R output to the servo plate amp. Would I run one of these cables to the plate amp for the servo subs, and the other to the plate amp for the "Classic" GR subs? Let me know if there's another way to do this. I can give it a try next weekend, although it'll be for experimentation purposes only -- wife's been tolerant when I added two subs, but 4 would be pushing the limits.

[rajacat]

You might want to play around with adding your old subs into the mix. They don't have to be at the same volume, just in different locations. Not more bass, but just smoothing out the room interactions. (The distributed sub theory) You may not have the space to keep it, but it would be interesting to try and see if you think it works just as an experiment.

I've thought about that too. Presently I have a custom ACI Titan which has a very nice cabinet but it's very heavy and would be a PITA to sell and ship. I've been yearning for a set of the GR OB subs so would be nice just to keep the Titan and use the OBs working towards a Swarm-like arrangement. Hmm...I wonder how the open baffle subs will interact with a quality traditional sealed sub. 

-Roy 

[drphoto]

cody, I'm guessing you'd want a splitter, so you're going into both inputs on the amp. I'm pretty sure it's a mono amp, but I dunno if you can into only one input and get full power. As this would just be an experiment, you wouldn't need an expensive 'audiophile approved "Y" adapter. The problem might be that it works, you love it....and your wife won't let you keep it!

Raja....only way to know is try it and see err...listen. I'm using my crummy old Mirage for the 'filler'. It's a bipole design, but still not OB. You basically don't even hear it playing.

[cody69]

After playing the servo subs for about a month to break in, it was time to do some serious listening and compare them to my classic GR SW/PR subs. I've been impressed with the bass from the classic subs, and wasn't expecting to hear such a difference from the servo units. I played one of Diana Krall's early albums, Love Scenes, that has some good bass tracks, and was amazed at the clarity and tightness of the bass. Each note was crisp and well defined; with amazing clarity to hear each note as it was played on the instrument. With the classics, the notes ran together more without as much separation, losing some of the definition. A few other albums with heavy drums provided similar experience. Originally I thought the servos were not putting out as much bass as the classics, but now I realize its that they're putting out a different bass -- cleaner and tighter.

As Danny would have predicted, the servos won this shoot-out, hands down, and have a position in my main listening room. As I lugged the classics down the stairs to connect to my shop system, I kept telling myself the following... THANK GOD THESE ARE NOT THE SANDBOX DESIGN... those suckers are really heavy