[russellberg]

I have a pair of X-SLS's, (which I love), as my mains and a sealed servo sub.  I am in the process of building a single open baffle H frame sub which will probably go between my X-SLS's.  There is an open room behind where the H frame will go, so it will have lots of breathing space.  Does anyone have any experience with combining OB and sealed subs?  Will this be a good plan or should I plan to use my sealed sub elsewhere?   

My amp, Yamaha A-S801, has the option of two sets of speakers, A & B.  I am planning to run the H frame off of high level speaker inputs.  Do I just run a speaker wire from the left side speaker outputs or do I combine the left and right in some way before running to the sub?  Thanks for your help I am pretty new at this.

[Big Red Machine]

Not sure about sealed or open sub piece. My first eyebrow raiser was your additional volume behind the speakers and now you are asking your sub to energize that and your existing room. You might need extra subbage! Probably makes it more a candidate for OB bass. Let the experts chime in.

[Early B.]

A rough layout of your room(s) with dimensions would be beneficial.

The open room behind your speakers is bad news for bass. Is there a way to re-configure the room so that your system and your listening position have walls behind them?

Do NOT combine the high level speaker inputs. 

[DigIndig]

I'm by no means an expert, but I would think you would want to pick one sub or the other. Two mismatched subs are going to have very difference response curves, so sometimes the bass might be uneven, and sometimes it would be lacking. The only option I could see working in that case is using a crossover or combination of hi-pass/low-filters so that the two subs are covering different parts of the spectrum - ideally based on their response.

I also agree that the extra space behind could be problematic, but not a non-starter. You may want to figure out if you have a piece of furniture or some other wall or partition you can use behind the sub. Else, you may need to resort to insane amounts of power or attempt to create a cardioid radiation pattern using the two subs in unison. Again, much easier with matched subs designed for that scenario/application. This is used in live sound applications, and I've never heard of anyone using it at home, but no reason it couldn't work.

[Early B.]

I'm by no means an expert, but I would think you would want to pick one sub or the other. Two mismatched subs are going to have very difference response curves, so sometimes the bass might be uneven, and sometimes it would be lacking.

The OP's drivers and amps will be the same (or very similar) on both types of subs, so there's no mismatch. Otherwise, you're correct -- attempting to integrate different brands and types of subs can be messy. 

Danny at GR Research used to set up his display rooms at audio shows with OB servo subs up front and sealed servo subs in the rear. It's not a problem if you can dial them in properly (easier said than done). Sealed subs are useful when you have space constraints. OB subs need plenty of room to boom.   

[sunnydaze]

My amp, Yamaha A-S801, has the option of two sets of speakers, A & B.  I am planning to run the H frame off of high level speaker inputs.  Do I just run a speaker wire from the left side speaker outputs or do I combine the left and right in some way before running to the sub?  Thanks for your help I am pretty new at this.

Not familiar with your sub, but my sub has high level inputs for both L and R channels.  When using only one sub I run the corresponding amp channel into each of them.  I guess the signal gets combined / manipulated inside the sub?

When I run 2 subs high level, I run L amp channel into L sub input (either one) and R amp channel into R sub input (either one).  Stereo subs.

[russellberg]

A rough layout of your room(s) with dimensions would be beneficial.




The open room behind your speakers is bad news for bass. Is there a way to re-configure the room so that your system and your listening position have walls behind them?

With my existing setup I am getting quite a bit of bass, my measurements are pretty strong down to 20Hz.  Here are my measurements.



Do NOT combine the high level speaker inputs.
Thank you so much!

[russellberg]

The OP's drivers and amps will be the same (or very similar) on both types of subs, so there's no mismatch. Otherwise, you're correct -- attempting to integrate different brands and types of subs can be messy.   

Yes, both my subs are from Danny so I am expecting they will integrate with each other well.  I am hoping for a best of both world's situation where I am hoping to find a balance between the SPL benefits of the sealed sub and the character and texture of the bass from the OB H frame. 

[russellberg]

Not familiar with your sub, but my sub has high level inputs for both L and R channels.  When using only one sub I run the corresponding amp channel into each of them.  I guess the signal gets combined / manipulated inside the sub?

Ok, that makes sense.  My sealed sub does not have high level inputs though so I am running it off the Sub Out from the Yamaha amp. 

[russellberg]

Danny at GR Research used to set up his display rooms at audio shows with OB servo subs up front and sealed servo subs in the rear. It's not a problem if you can dial them in properly (easier said than done). Sealed subs are useful when you have space constraints. OB subs need plenty of room to boom.   

I am hoping that placing them in between the X-SLS's  will allow them the room that they need.  Maybe it is too much though?  There will be 11 feet behind them to the next wall.

[Tyson]

I am hoping that placing them in between the X-SLS's  will allow them the room that they need.  Maybe it is too much though?  There will be 11 feet behind them to the next wall.

It'll be fine.  OB bass does best well away from boundaries and close to the speakers.  Box subs do best in the corners. 

[Early B.]

Yeah, an OB sub in the middle of your speakers will be OK. I'm sure you have plans to build a second OB sub at some point. Dual OB servo subs with a sealed servo sub in the rear will take the full spectrum of sound (not just the lows) to another level. 

[Digi-G]

A box sub in the corner hasn't yielded the best results for me.  Yes, it produced a lot of bass, but at the expense of exciting room modes that I couldn't tame.  Midway along the wall (side walls in my case) has worked best for me, in two different rooms.  I definitely understand why two or more subs would help.  Of course YMMV.

[Scott Joplin]

Having different subs is an advantage, the more variation in placement and response the better to fight room modes. If you want to maintain the benefit of OB I'd suggest you crossover between it and the sealed sub.

[russellberg]

So, I finished the OB H Frame and I absolutely love it!  There is a whole new character to the bass that I had never experienced before.  This is what my setup looks like.


My concerns about loosing all of my bass into the room behind were unfounded.  For now I have been leaving the sealed sub off and my music has been a truly wonderful experience.  I have been listening for hours and hours on end.


These are my measurements without the sealed sub running.  I realize there is still some work to do but it is pretty good.  I have decided not to try and integrate the sealed sub for music listening until I have had some solid time with just the OB playing the low notes, so I get a really good sense of how that sounds.  I want the sealed sub to add to the experience in a subtle way, not dominate so I want to make sure I have a good handle on the auditory experience of the OB sound before I start mixing it in.

I have turned on the sealed sub in HT mode when watching movies and that has been really positive as well.  All in all, right now I feel like I've got something really special here.

[Early B.]

All in all, right now I feel like I've got something really special here.

Awesome, huh? And you're just getting started. Integrating the sealed sub may not be as challenging as you think. Place it as close to your listening position as possible, set the phase opposite of your OB sub, put the volume at the noon position and the crossover the same as the OB sub. Tweak, as needed. Also, try using both subs for HT.

 

[Jonathon Janusz]

The finished sub looks really nice!  I'm glad that it is working as well or better than you hoped!

Running with what Early B. said, you're on the right track thinking to implement the sealed sub as a subtle piece of the puzzle.  Expanding on what was said earlier, in broad strokes, the way Danny generally integrated sealed subs in his open baffle setups at shows in the past was:

• put the sealed subs in the back of the room, pointed at the front wall
• set the phase 180 degrees out of phase with the mains
• set the cross over very low (don't quote me but 40Hz-ish sounds right in my head)
• set the volume level/gain very low compared to the mains

If I remember correctly, the overall goal was to add in the impact/weight at the very bottom of the frequency range that the sealed subs excelled at without muddying what the open baffle subs were doing higher up.  The sealed sub will be barely playing relative to the mains, but in my experience the effect is a noticeable step up. 

[russellberg]

Thank you to both Early B and Jonathon.  I hadn't thought of cutting the sealed sub off so low.  I think thats a great idea.

[corndog71]

If you decide to use both subs then I would split the RCA sub out from the receiver to both sub amps.

[russellberg]

If you decide to use both subs then I would split the RCA sub out from the receiver to both sub amps.

Oh, interesting.  I wasn't aware that I could do that.  Do I just find a Y RCA adaptor?  The only problem I see here is that my amp has a built in 100Hz cutoff on the RCA sub out and I was hoping to keep the OB's playing a little higher to help out with the higher end of the bass.