[Larpy]

I'm a recent convert to open baffle speakers.  I listen to DIY Lii Audio F15 open baffles in a small room (12" x 13" x 9").  I get reasonably flat bass down to 65 or so Hz but output drops like a rock below that, so I want to build one of the GR Research sub kits.  Given my small room, I don't really have space for the conventional OB H-frame with dual drivers, but I could build two separate smaller H-frames and put one driver in each and place each each H-frame underneath each of my F15 baffles (using a single sub amp in mono).  That's the only way I can see getting the OB sub drivers far enough from the front wall.

Would such a set up work? or would it make more sense to build the (sealed) sub kit 2 and put the sub in the corner of the room?  I'd rather have OB bass, but if placing a single-driver H-frame under each of my FR baffles isn't a good idea, then I'll settle for a sealed sub.

Here's a photo of the room (as you can see, my listening spot is only 6' or so from the speakers).

[guf]

I don't have OB subs but often want and ask questions about how to make them work in various situations i've had. Suggesting the following because it was suggested to me.....how about single dual in the center or I bet you could get 2 duals and lay then horizonital with the Lii ontop of them.

I'm sure more will chime in.

[Larpy]

The room is small.  There's only 32" between the two FR baffles, so a dual H-frame would take up this much space:



It would be difficult to get to the equipment!

[mikeeastman]

I would wait for Danny to answer, But in that small of a space I would think a single H-frame under each speaker would be more than enough bass.

[mlundy57]

You'd have to connect one sub to the amp and connect that sub to the other sub as if both drivers were in the same cabinet. I don't know what effect that length of wire to the second sub would have on the servo control. Likely it will pose problems but Danny would need to chime in on that.

Using a single driver sealed sub under each speaker would work and not have any control issues since each driver would have it's own amp. The character of the bass won't be the same as if it was OB bass, but the bass response will still be very good.

Mike

[Early B.]

Build new speakers that conform to your room.

[Larpy]

Meaning smaller baffles using smaller FR drivers so that they'd fit on top of two dual H-frame subs?

If so, I'm open to suggestions.  As I explained, I'm new to OB.

I do have a pair of Caintuck Betsys with Lii Fast 8 drivers, and they would obviously better accommodate two dual H-frames in my room, but the Fast 8s start rolling off at 500 Hz, so that's why I built the bigger baffles with the bigger drivers. If I used dual servo H-frame subs with the Fast 8s, I fear that I would end up with a 200-500 Hz suckout (–6 to –8 dBs).

With the 15" FR drivers in larger baffles, I get relatively flat output to 60 Hz or so.  Hence my interest in adding a sub.

But if you think I've got this ass-backwards, it wouldn't be the first time I've waded into deeper water than I expected, and I'm willing to be enlightened.

[Hobbsmeerkat]

You can always go with 2 dual subs topped by NX-Otica MTMs or NX Studio both should make for a great experience that won't take up any extra room, aside from a little extra vertical space, that should also put the tweeter height closer to your listening position.

[Early B.]

Meaning smaller baffles using smaller FR drivers so that they'd fit on top of two dual H-frame subs?

If so, I'm open to suggestions.  As I explained, I'm new to OB.

For your room size, I'd go with NX Studio monitors with a single sealed servo sub. Once you get into a larger room, build the dual OB servo subs with the NX Studio monitors on top, and you'll be in hifi heaven.

[Larpy]

I'm open to considering a new set of FR OB speakers (though I really like the sound of the Lii OBs), but I'm using a 300B amp: from what I've read about the NX Studios, they need more power than 8 watts.

[Early B.]

...but I'm using a 300B amp: from what I've read about the NX Studios, they need more power than 8 watts.

For your size room -- I seriously doubt you'll need more power than 8 watts.

[Hobbsmeerkat]

I'm open to considering a new set of FR OB speakers (though I really like the sound of the Lii OBs), but I'm using a 300B amp: from what I've read about the NX Studios, they need more power than 8 watts.

If i remember right, Danny also has a custom/modded 300B, and he has used it to power the NX-Tremes, so i imagine it'll be plenty of power, esp in a small room like yours. 

[Danny Richie]

You can go with a single pair in the middle of the room to power in mono.

Or you can add a single SW-12-08 woofer in a H frame under each of your speakers, but they will each need their own amp. You can't separate the two woofers using one amp without the added lengths of wire and time delay causing a control problem.

[Larpy]

Thank you, Danny.  That's helpful info.

[Larpy]

UPDATE:

I ordered a single servo subwoofer driver and a A370PE amp (I figured I'd start with one and buy a second driver and amp after next payday) and built two single-driver H-frames (thinking I might as well make two at a time if I'm going to use two eventually).

My big "barrel" OBs with Lii F15s looked ridiculous atop the H-frames, so I decided to modify them and make them more streamlined.  Since I wasn't worried about keeping the baffle a certain size for bass extension, I came up with this new configuration:



It's a bit odd looking at an empty H-frame but here's the deal:  the bass even with a single sub driver sounds great.  Granted, it took me a couple of days of tweaking and measuring SPLs, but the result is everything I could have hoped for:  virtually linear (within 2 or so dBs) bass response down to 32Hz.  I'm only 6 dBs down at 28Hz.  It's amazing to hear such low bass in my small room.

And the transition from the F15s to the servo sub sounds seamless.  My head knows that frequencies below 80Hz are handled by the servo sub and those above are handled by the F15s, but my ears just hear music.

So here's the thing: I don't think I need any more bass than the one servo woofer is giving me.  On the other hand, I've got the second H-frame all ready for a second sub.  It also means buying a second A370PEQ, so I'm wondering if it's worth it.

Given my small listening room (mine is 12' x 13' x 9'), a single sub seems to suffice.  So what, if any, would be the advantages of adding a second one?  I might be talked into adding a second if there's a strong argument in favor of doing so.

But in addition to this question, I'd also like to commend Danny and Rythmik Audio for making such a great subwoofer kit.  It really is as great as so many of you claimed on this forum.

[mlundy57]

UPDATE:

I ordered a single servo subwoofer driver and a A370PE amp (I figured I'd start with one and buy a second driver and amp after next payday) and built two single-driver H-frames (thinking I might as well make two at a time if I'm going to use two eventually).

My big "barrel" OBs with Lii F15s looked ridiculous atop the H-frames, so I decided to modify them and make them more streamlined.  Since I wasn't worried about keeping the baffle a certain size for bass extension, I came up with this new configuration:



It's a bit odd looking at an empty H-frame but here's the deal:  the bass even with a single sub driver sounds great.  Granted, it took me a couple of days of tweaking and measuring SPLs, but the result is everything I could have hoped for:  virtually linear (within 2 or so dBs) bass response down to 32Hz.  I'm only 6 dBs down at 28Hz.  It's amazing to hear such low bass in my small room.

And the transition from the F15s to the servo sub sounds seamless.  My head knows that frequencies below 80Hz are handled by the servo sub and those above are handled by the F15s, but my ears just hear music.

So here's the thing: I don't think I need any more bass than the one servo woofer is giving me.  On the other hand, I've got the second H-frame all ready for a second sub.  It also means buying a second A370PEQ, so I'm wondering if it's worth it.

Given my small listening room (mine is 12' x 13' x 9'), a single sub seems to suffice.  So what, if any, would be the advantages of adding a second one?  I might be talked into adding a second if there's a strong argument in favor of doing so.

But in addition to this question, I'd also like to commend Danny and Rythmik Audio for making such a great subwoofer kit.  It really is as great as so many of you claimed on this forum.

It will definitely be worth it. going from mono bass to stereo bass is a big step up. It is like having a pair of full range speakers that play down to 20Hz in stereo.

[Tyson]

Stereo bass for the win!

[Early B.]

Definitely another woofer. 100%.

Hey guys -- would the OP need a second 370 amp if he purchased another servo woofer?

[mlundy57]

Definitely another woofer. 100%.

Hey guys -- would the OP need a second 370 amp if he purchased another servo woofer?

Without the second amp he wouldn’t have stereo bass.

[Larpy]

Yes, earlier in the thread Danny said I'd need a separate amp for the second sub.  I think the issue is running servo cables more than a few feet won't work.