[robbo266317]

I have a pair of Shiva X's which I am going to use in my new three way speaker system (when we get the new house built) & I was wondering if they could be used in an extended bass shelf design.
I don't listen to music or movies at high levels but would like to get a bit deeper bass.
My current amp is the Pioneer VSX 710 and I rarely get it above -45.

This is what I was thinking

 

[Mike P.]

Re: Shiva X extended bass shelf

It would definitely work. What will you power the Shiva-X's with? Have you figured out the dimensions of the box to see how big that is?

 

[robbo266317]

Re: Shiva X extended bass shelf

The pioneer has a sub amp built in, mono only, with adjustable gain for all speakers.
It's only a stop gap measure to utilise these till we get the new place built with dedicated room,
The pioneer is 120 Watt per channel. I tried to get it tuned as low as possible as I don't know if the amp has any LPF built in to prevent over-excursion.
As for the box, I have no real plans yet, I would consider getting a sonotube to minimize footprint.
A large box won't fit in the room as it is. I had contemplated using the fireplace and chimney.... but a sonotube may be the best bet as we currently have ten foot ceilings.

 

[Mike P.]

Re: Shiva X extended bass shelf

You mean a high pass filter, you probably won't be needing one with this setup. If you're planning for future use, the sub will handle 360 watts with Xmax being reached at just under 12 hz. Porting will have to be a 6 inch diameter to keep the air speed down. SpL is 107 db in the 13 - 20 hz range, plus room gain.

 

[robbo266317]

Thanks Mike,
That was what I was aiming for.

HPF... LPF... It's late - 10:30, I've had several glasses of a very nice hunter shiraz :neener:

Until I found this forum I hadn't realised that you could buy the "sonotubes" even though I had seen them on building sites. I must download the software and have a play.
Is there a height from the floor that they need to be based on driver size?

 

[Kevin Haskins]

Thanks Mike,
That was what I was aiming for.

HPF... LPF... It's late - 10:30, I've had several glasses of a very nice hunter shiraz :neener:

Until I found this forum I hadn't realised that you could buy the "sonotubes" even though I had seen them on building sites. I must download the software and have a play.
Is there a height from the floor that they need to be based on driver size?

You just need a box big enough to fit the port. Tuning it low with a large port requires long lengths.

Kevin Haskins
Exodus Audio

 

[robbo266317]

You just need a box big enough to fit the port. Tuning it low with a large port requires long lengths.

Kevin Haskins
Exodus Audio

Thanks Kevin.

Mike, how did you save your winisd plots? they are much clearer than mine.
I did a screen shot and pasted in Adobe Photoshop and changed the resolution to 800x600 then jpeg'd them.

 

[Mike P.]

Paste the screen shot in Paint. Select and cut the part you want and paste into a new Paint window. Save as a jpeg. Open you Pictures folder and resize the pic to "small" with Image Resizer.

http://www.microsoft.com/windowsxp/Downloads/powertoys/Xppowertoys.mspx

 

[robbo266317]

I have been looking at the Sonosub software and it has the option of a top cap over the port, is this just to keep things from falling in or does it help with the sound?

 

[Mike P.]

It's just for looks and port protection.

 

[robbo266317]

OK I have ordered a 45 cm "Form-a-Tube" and it should arrive monday. :yay:

 

[robbo266317]

Update:
After phoning the hardware store and asking about cardboard Sonotubes they said they didn't have that brand but did have "form-a-tube" in 457 mm width, which I promptly ordered to be delivered.
Upon delivery the tube is made from 2 mm sheet metal! So I sent it back.
I phoned the Sonotube importers to find if there are any distributors close by and the closest is 2 1/2 hours away.
Did more searching and found a build using laminated ply. This looked promising so I did the calculations and it only gives a tube of 400 mm which means it would have to be 2.5 m long.

Back to the drawing board...

 

[robbo266317]

Ok, I'm going to try to make a tube fromlight guage MDF.
I figure a diameter of 470 mm or 18 odd inches should put me in the ballpark.

The thread I found using 3 sheets of 1.5 mm ply to make a thickness of 4.5 mm or 1/4" doesn't seem practical as "Mr Plywood" want's au$80.00 per sheet.

I am thinking of building it with three legs from floor to top of port and the MDF routed into slots running up the length of the tube with internal bracing to keep the shape.

 

[Mike P.]

Contact Sam at:

http://www.affordabledrivers.com.au/

He may be able to help you out with the sonotube.

 

[robbo266317]

Thanks Mike,

I will send them an email to find out pricing and delivery. (the delivery might put it over budget as they are 500 miles away)
I haven't seen any builds like I'm contemplating so I might just go ahead anyway and see how it turns out.

It would definitely work. What will you power the Shiva-X's with? Have you figured out the dimensions of the box to see how big that is?

I sketched out the size of the internal baffles and you're right, it's going to be BIG.
However, I checked the corner of the room behind the tv and there is enough room.

 

[robbo266317]

OK, I have cut out the internal bracing and routed the legs to suit.

Next is to join the sheets of mdf, one is 1.2 m and the other is .9 m which comes out at about 6' 6" and about 18" in diameter.

 

[robbo266317]

The Sonosub calculator says that the main resonance is around 85 Hz and to add damping at the end.
I was wondering if I cut a circle out of the thin mdf and made a spiral in the tube at about 2/5ths the length if this would break up the resonance.
Has anyone tried this?

 

[Mike P.]

I've not heard of doing that, can't say for sure if it would work. Damping the top cap is easy enough though.

 

[robbo266317]

OK, Here is the Top Plate with a rough coat of primer.

And Bottom:

 

[Kevin Haskins]

Looking good! I like everything I see, especially that flared exit for the port.

Kevin Haskins
Exodus Audio