EBS Shiva Sonosub complete (1 Viewer)

[Greg.K]

My long sub-less nightmare is over! For the past couple of years, going back to when the Shiva was new and the first sonosubs were being discussed in this forum, I've been planning on building one of these things. In fact, I bought the 12' of 16" tube and it's been sitting in my garage, waiting until the budget & my spare time allowed me to complete it.
I finally was able to build the thing, so here it is: Link Removed
My intial tests (very informal, although I've made a test tone CD and used a Rat Shack SPL meter) show that it does get down low enough, with plenty of output into the low 20s. It also gets plenty loud enough for me when driven by my old Pioneer reciever - no complaints there.
The only thing I've not liked about it so far is that it seems to have a bit of a boominess to it - But I haven't narrowed that down to the room, the driver or maybe even the receiver I'm using.

 

[Greg.K]

I made some frequency response measurements this weekend, using the Spectra+ demo & my Radio Shack SPL meter as a microphone:

The only things that really concern me are them the peak at 70 Hz and the null at 63 Hz. I'm pretty sure the measurement is accurate. It is pretty audible difference, especially since they're so close together.
I was a bit surprised by the boost right below 20 Hz.
Now, I also did this without applying the correction values for the SPL meter that are floating around. If I do that, the response looks pretty bizarre, with the hump below 20 Hz getting huge.. I'm not sure if I can trust these numbers, maybe I should use some other means of measurement?
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On another subject, a question: - My main speakers right now are a pair of NHT SuperOnes, (2 SuperZero XUs as surrounds). My center channel right now is the weak point in my audio system, it's an older Radio Shack bookshelf speaker with a tweeter canabalized from another speaker, and I want to replace it. I was planning to get either another SuperOne from OneCall, since they're pretty decently priced now that they've been discontinued. Another possibility is an NHT SuperCenter from the same place.
However, I wouldn like to investigate going the DIY route for this speaker too. I would want something that would fit in tonally (although it's not like my current center does). I might also want to upgrade the other speakers in my system some time down the road too.
Are there any kits out there that might be a good candidate?

 

[Jack Gilvey]

Nice job!

 

[Anthony_Gomez]

Hey Greg, without EQing, those numbers aren't abnormal at all. They look all room induced.
Try playing around with the following program. Changing the absorbtion coefficients with change the magnituded of nulls/gains, but the over alll picture will still be there.
http://www.pvconsultants.com/audio/reflection/rrc.htm
(good job with the sono!)

 

[Anthony_Gomez]

On the subject of spectra plus....I installed it and used it on this comp some time ago. Anyway of re-installing the program or such to get rid of the previous install artifacts?

 

[Greg.K]

Anthony, thanks.. that's a nice tool. I had tried to model room response in LSPCad but must have messed it up somewhere. Just doing some rough numbers I get this:

Hmm, looking at the predicted results, it looks like the meter correction results might be right after all, and I have an even larger peak at 18 Hz than the uncompensated graph indicated. I just updated that pic to show the compensated values..
It all seems to be due to my family room not having a right side wall, it's just open to the kitchen & then past that a wide opening into the dining room. So I guess I'm happy that everything is working as it should be at this point. The sub sounds great, too.

 

[ColinM]

About the center - Consider a BIC 62CLR - it matches well with the 'Ones in my room, from ubid for $80 shipped. Not exactly DIY, but...

Looks good!