12" Replacement Driver for my DIY Sonotube Sub - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 10 Old 05-20-2020, 12:11 PM - Thread Starter
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12" Replacement Driver for my DIY Sonotube Sub

Back in 2001, I built a sonotube sub with one of the original Adire Audio Shiva drivers. It's a dual voice coil driver (8 ohm per coil), and while I can't find a spec sheet for it, or remember what the ratings are, I believe it's somewhere around 200 watts.

When I designed the enclosure for it, I took the TS parameters of the Shiva and used WinISD and LspCAD to work up the specs. I ended up with a 160l (5.65 ft^3) enclosure using 24" sonotube with internal height of 23". I also ported it with a 16" long, 4" wide, dual flared port.

The sub has been working great for years, and I currently have it connected to a Carver x400 amp (200w per channel at 8 ohm).

I found some old notes from when I built this, and I think it has a tuning of 23Hz with excursion limits being reached at 30Hz on 200w, and estimated 105dB @ 1m. Which was great for my previous room size and setup.

Here is how it performs, after using REW to define PEQ settings and applying them to the sub.




Well, I've moved several times since building this, and am now in a much larger house and living room, and would like to get more output from it .... so I was kicking around the idea of modifying it with a higher power driver and a new amp, to increase the output. But when searching for replacement drivers, all the ones I'm finding are designed for much smaller enclosures than what I have.

Ideally, I'd find a dual coil (4ohm per coil) driver, which would work well in this large enclosure I have, but capable of 500w or so. Anyone know where I can find drivers like this, or have a recommendation on a replacement?
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post #2 of 10 Old 05-21-2020, 06:27 AM
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Can you rebuild the base or enlarge the opening for a 15" driver? What is your budget for the "better" 12 or even a 15? What drivers have you looked at?
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post #3 of 10 Old 05-21-2020, 07:51 AM
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Some 20 years ago when Adire hit the scene, I purchased their Rava sub, which houses the Shiva driver. It still works without any issues too. Here is a pic from their manual on the specifications of the driver. It states that it can handle up to 650 watts.
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post #4 of 10 Old 05-21-2020, 09:27 AM - Thread Starter
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Quote:
Originally Posted by rlj5242 View Post
Can you rebuild the base or enlarge the opening for a 15" driver? What is your budget for the "better" 12 or even a 15? What drivers have you looked at?
Yes, the base could definitely be modified to fit a 15" driver ... When I built this almost 20 years ago, I was doing it on a very slim budget. I'm in a much different position now, and could definitely go for a quality 15" driver if it makes sense to do so

I think I'd be comfortable spending $200 - $300 for a better driver. I looked at Adire's current offerings, as well as Dayton and Eminence. All of their 12" drivers suggest a much smaller enclosure than what I have though.


Quote:
Originally Posted by shivaji View Post
Some 20 years ago when Adire hit the scene, I purchased their Rava sub, which houses the Shiva driver. It still works without any issues too. Here is a pic from their manual on the specifications of the driver. It states that it can handle up to 650 watts.
Thanks for this! I used the Wayback Machine to try and find the original Shiva specs, and best I could find was this page with whitepapers on Shiva implementations (sealed, vented and passive radiator)

Shiva Page on Wayback Machine

Here is what is in the vented doc for amp selection:

Quote:
Originally Posted by Adire Audio
2.1 Power Amplifier Selection

At first glance, Shiva would seem to indicate a need for a 600W amplifier, since that’s the power rating of
the driver. However, this is not the case. Very good results can be achieved with Shiva running from as
little as 40W per channel. Even smaller amplifiers (10WPC) can result in a musically satisfying
experience. It really depends upon your tastes and the capabilities of the loudspeakers paired with Shiva.

The 600W rating of Shiva is just that: a maximum power rating. This is the peak amount of power that can
be dissipated in Shiva over the long term. Realize that this level of power would yield an in-room output in
the 120 dB SPL range; this level is well beyond the typical continuous home listening environment.

However, assuming a source peak-to-average ratio of 25 dB (such as is typical for modern music, FM
broadcasts, and most soundtracks), listening at normal levels (80 dB SPL) would require peaks of 95 dB
SPL. This peak level requires 17.5 dBW, or 56.2W of amplifier power. As such, most home receivers
capable of 100W per channel performance will be quite suitable for use with Shiva.

We do realize that such listening levels (80 dB SPL nominal) are not for everyone. Some individuals will
listen to Shiva at higher levels. The 600W rating is intended to allow for those who enjoy musical peaks up
to and beyond 120 dB SPL in-room.

As with all acoustic transducers, we strongly recommend that you exercise good judgement when listening
to your loudspeakers. High power/high SPL capable drivers such as Shiva can cause permanent hearing
damage and actual hearing loss, if abused. Prolonged exposure to levels in excess of 110 dB can cause
partial or full deafness. Be kind to your ears!

My current amp (Carver a-400x) is rated at:
  • 200wpc @ 8ohm
  • 300wpc @ 4ohm
  • 500w bridged @ 8ohm.

In hindsight, I wish I had opted for the dual 4ohm coil Shiva instead of the dual 8 ohm coil version they used to offer ....
The original amp I used when I built this was the Adcom 545 (100wpc @8ohm). I got the Carver some time afterward.

How are dual coil drivers rated? Is it 600w per coil, or 600w total (both coils)? It's too bad the Carver isn't stable at 2ohm, as both coils wired in parallel, for a combined 4 ohm load, then bridged to the Carver would produce quite an increase. Although I'm not sure the amp would handle it.

Since the Shiva is rated at 600w, it looks like I could just get a new amp rated for 600w @4ohm load, wire the coil in parallel, and it should perform well with a nice increase in output. Although my notes from back then suggest I'd hit the driver's excursion limit @ 30Hz with 200w. Although I don't recall how I came to that conclusion

Does your manual/document happen to have the TS parameters of the original Shiva driver?

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post #5 of 10 Old 05-21-2020, 09:36 AM - Thread Starter
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Ahh, I found the TS specs in the Wayback Machine as well.

Shiva White Paper


Here is the table from the doc showing the TS parameters





So it's 650w total, or 375w per coil. I suppose I should just reinstall WinISD and/or LspCAD and start playing with different power ratings for my enclosure to see the result.
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post #6 of 10 Old 05-21-2020, 12:49 PM
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Quote:
Originally Posted by Stoopalini View Post
Yes, the base could definitely be modified to fit a 15" driver ... When I built this almost 20 years ago, I was doing it on a very slim budget. I'm in a much different position now, and could definitely go for a quality 15" driver if it makes sense to do so

I think I'd be comfortable spending $200 - $300 for a better driver. I looked at Adire's current offerings, as well as Dayton and Eminence. All of their 12" drivers suggest a much smaller enclosure than what I have though.
I'd definitely move up to a larger driver. 18" if you can squeeze it in.


$300 is a great budget. Try modeling subs like these. There are dozens of other options as well.

https://psicaraudio.com/product/15-bass-line/
https://ficaraudio.com/product/xv3-series/
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post #7 of 10 Old 05-21-2020, 01:34 PM
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A single 4 inch port will not be enough. A better sub will move more air which needs more port area. You're going to run into a problem getting a long enough port into that short box. Increasing the port area to accommodate the more powerful driver will also require a longer port for the same tune. In a sonotube your port locations are limited, and your box is only 23 inches tall. I guess you could use an elbow to add length.
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post #8 of 10 Old 05-22-2020, 07:41 AM - Thread Starter
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Thanks guys, I appreciate the input.

So I reinstalled WinISD, and have been playing around with different configs.

When I originally built this sub, I powered it with an Adcom 545, which is 100wpc @ 8ohm. WinISD shows the cone excursion to be right at the limit with 200w.

Now that I am running it with the Carver, which is 200wpc @ 8ohm, looking at the WinISD models ... I now understand why I am hearing pops at high volumes (it appears the driver is reaching the excursion limit.

I sit about 12ft away from the sub, which is probably why I'm wanting to increase the output from the sub now.

So in playing around with WinISD, and modeling different configs ... it looks like I could add another Shiva in an isobaric config (cone to cone), and then wire each driver's coils in parallel, to create a 4 ohm load on each on the Carver's channels.

The Carver amp produces 300wpc @ 4ohm, so this would be 600w total system power, split across all 4 coils of both drivers.

Modeling this in WinISD shows a significant increase in SPL, and a much better cone excursion graph.



Here is the SPL graph of the 2 setups in comparison:







And here is the Cone Excursion graph, comparing the two designs:







So would this really be as simple as sourcing a 2nd dual-8ohm Shiva (with the same TS params), and bolting it to the cone of the existing, and wiring them up to the Carver?

Or is there something I'm missing with this approach?
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JBL Performance AVA7 / Mitsubishi DA-A10 / Carver a-400x / Adcom GFA-545
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LG OLED65CXUAP / Vizio M602i-B3 / Dell 5100MP
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post #9 of 10 Old 05-22-2020, 10:30 AM
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Sorry if I missed it but are there size or location requirements? Could the answer be as simple as buying a VBSS with an inuke? OP stated replacing the amp also. If 2-300 is only for the driver that would get pretty close for the enclosure and driver.

Or an multitude of sealed jbl 12" near field.
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post #10 of 10 Old 05-22-2020, 10:32 AM
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How about an UM12 or 15? The port velocity would need to be checked but I believe both of those would do fine in that sized enclosure.
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