[jlafrenz]

I'm thinking of building an OB sub for my 2 channel room after several suggesting it was the way to go. With space and budget concerns, I am hoping to build using only a single driver. I see that several designs, including Danny's are for dual drivers. Those who have only single driver cabinets still have 2 in the room. So my first question is that will a single driver setup work? The room is roughly 12x14 and I don't intend on having a rock concert in there. The second question is what type a box design would be idea for my situation?

[TRADERXFAN]

Just going to be resticting the potential output. A simple design is all you would need. Take half of the v1 sub design which would be a 13" deep open frame with a baffle in the middle holding the driver.

The output as you drop in frequency will be limited. But depening on what you want it could be fine to fill in some low end without overdriving it.

-Tony

[jlafrenz]

Thanks Tony. That design seems simple enough. I'm not looking for tons of output. Just filling in a little low end and giving my system a bit more umph. The drop off is something that others have stated and I read about. Also in the little reading I have done, it has been suggested that a U design may help compensate for the db loss of OB designs. Would this be a better design than the H frame you suggested? OB is completely new to me so I'm looking to get educated.

[ebag4]

Thanks Tony. That design seems simple enough. I'm not looking for tons of output. Just filling in a little low end and giving my system a bit more umph. The drop off is something that others have stated and I read about. Also in the little reading I have done, it has been suggested that a U design may help compensate for the db loss of OB designs. Would this be a better design than the H frame you suggested? OB is completely new to me so I'm looking to get educated.

I seem to recall Danny stating that he looked/tried a "U" frame alignment for the servo subs when he was developing the V series, ultimately he chose to go with the "H" frames.  I believe he mentioned other issues with the "U" that made the "H" more attractive. 

I'm not certain this is the statement I am remembering but this is a comment by Danny in an earlier thread:

Also, I would highly advise against a U shaped frame. Most utilize them with no bracing at all. Then the panel size is such that they flex and resonant wildly. At least the H frame breaks the panels down to half their size. That helps a lot, but can still be a problem. Even a friend of mines Orion's allowed a LOT of low frequency coloration due to panel flexing and resonating. I used 1.25" thick side panels on the Super-V and it still needed to be lines with No Rez to kill the resonances completely and provide a solid bass response.

Danny could certainly answer this, give him a call or send a PM.

Best,
Ed

[JohnR]

The second question is what type a box design would be idea for my situation?

With just a single driver and no measurement capability (I assume), I would quite honestly suggest that you should look into the sealed versions. Next spend should be on a basic measurement setup - then you can optimize the position of that one sub. You can go from there as budget and space permits. You will always be able to use a high-quality sealed sub as a part of any subwoofer system.

[mcgsxr]

A single sealed sub is a great way to integrate additional bass into any system I agree with that.

To answer the original question, I have run a single OB 12 in an H before, and found it OK, but it needed EQ to keep up with the rest of my system.  That EQ'ing soon led to XMAX issues with a single woofer on OB in my 25x35 basement, and need for big bass.

For a more restrained implementation, in a smaller room, you might get away with it though.

[jrebman]

Just curious, why do H frames always (or is it my imagination) have the drivers in a vertical alignment instead of lateral?

Also curious if the 370 PEQ amp is designed for a 16 ohm load and what would the power be at that load?  Any other drawbacks/benefits to using one 16 ohm driver here?

Does anybody have any updates on the 8 inch servo drivers?

-- Jim

[Danny Richie]

I'd do an H frame with two of them if any at all just for the increased output capability. If I could only do a single woofer then the sealed SW-12-04 is ideal.

Just curious, why do H frames always (or is it my imagination) have the drivers in a vertical alignment instead of lateral?

They can be laid either way.

Also curious if the 370 PEQ amp is designed for a 16 ohm load and what would the power be at that load?  Any other drawbacks/benefits to using one 16 ohm driver here?

No, the amp is designed to reach make output levels into a 4 ohm load.

With a single SW-12-16FR it will only peak about 170 watts.

Does anybody have any updates on the 8 inch servo drivers?

finally in production this week.

[jparkhur]

Danny...specs on the 8 s out for us....

[jrebman]

Thanks, Danny, helps a lot.

-- Jim

[jlafrenz]

Danny, do you suggest a single 12-04 only because of output levels with one sub or are there other reasons? I was interested in OB designs as many have suggested that it is a great option in a 2 chanel system. Its not a big room, but if you still advise against it I may need to rethink my build. My goal is quality over quantity.

[corndog71]

A single sealed servo sub is the way to go.   

[jlafrenz]

A single sealed servo sub is the way to go.   

 

That's what I was originally going to build, but then several people recommended OB and that got me intereated in going that route.

[Danny Richie]

If you are looking at a single woofer purchase and a single amp then the sealed version is the ticket. It will give you a lot of output and a performance level not matched by any other boxed sub.

Open baffle plus servo control takes it to another level. Nothing touches it. However, I'd recommend at least a pair on a single amp or even three of them. Many close a left and right pair combo like what's used in the V-1 and Super-V kits. Now you are talking performance and output levels.

It just depends on how much of a good thing that you want, and how much you're willing to spend to get there.

[jlafrenz]

I would love to do dual subs in separate areas, but space is limited and I am trying to watch the budget. Will I loose that much output from an OB sub that a single 12 won't have enough to fill in the low end in a spare bedroom?

[Danny Richie]

Open baffle woofers aren't going to give you as much SPL output as a sealed box design.

Plus the high impedance of a single 16 ohm woofer will reduce the maximum output of the amp to 170 watt peaks. So don't expect a lot of output.

The single 4 ohm SW-12-04 in a sealed box will allow the amp to produce a solid 370 watt peak power output (quite a bit more power). Same price too.

Also, keep in mind that an open baffle sub needs to be well out into the room (at least 3 feet or more), while a sealed box design can be placed right up against a wall.

[jlafrenz]

Assuming an H frame design and having the position of the sub driver itself at 3ft out into the room, that would put the front of the baffle at about the same distance from the front wall as my speakers. This would fit in my room, but then my concern becomes the fact that my listening position is do close (due to room size) that I would be sitting at a 45 degree angle from the front of the baffle. From what I gather is that this may also hinder me as the sides are dead spots so to speak. I could toe in the sub a bit, but at the expense of distance from the front wall. Am I correct in my undersanding and how it will play in my room?

I can also see where the power can be an issue. This along with position may drasticly hinder output and performance for my setup. Please correct me if my assumptions are not correct here.

[Danny Richie]

I would be sitting at a 45 degree angle from the front of the baffle. From what I gather is that this may also hinder me as the sides are dead spots so to speak.

That would put you in an area where it will start to null.

I could toe in the sub a bit, but at the expense of distance from the front wall. Am I correct in my undersanding and how it will play in my room?

Towing it in will work well even if it is now a little diagonal to a side wall.

However, a single OB woofer is not going to give you much output.

[jlafrenz]

Toeing it in would put the rear of the baffle aimed more towards the corner of my room where there is a bass tap. I aime this would be acceptable. Now the issue that I face is output. What level of output would be expected in a room this size with only a single woofer (if posible to estimate)? I can get ot the SPL meter and verify some of my listening levels to see if they are close.

[dvenardos]

If you are really set on OB you could start with the single and then add a second one later on...