Help, I have a Shiva Mark IV, with a Rythmic 350 amp with the shiva in parrall so its 4ohms. I also have the setup in a 142 liter box. Heres my problem - After turning the amp up to 50%, with the crossover at 40hz and the phase at 0, i was watching the Italin Job. During the vault explotion and the truck drop explotion, the Shiva made huge popping sounds. Note that my reciver was not turned up very high, at most -30Db. I then experimented, aka tested other movies and songs, with the Shiva only to find that it sounded terrible. I took it out and check it, and i found that the spider had come loose. I was wondering if my voice coils are burnt and if so what should i do. Buy another shiva or send it in for repairs. Thanks.
Generally drivers are not covered under warranty for excess power. In your case ths spider tore from overexcursion, which may be from excess power or may be caused by an incorrect box design. Is your box vented? That's the usual cause for excess excursion. Even if you luck out and the driver is warranteed you need to correct the source of the problem or it wil reoccur.
Both voice-coils should be alright. I had an accident once, my amp blew up and shorted its positive supply rails to 1 of 2 coils. Imagine the horror seing the cone pushing all the way out 
The Shiva was fine, coils and suspension survived 
But I'd still have it checked out just in case.
Cheers!
The Shiva was fine, coils and suspension survived But I'd still have it checked out just in case.
Cheers!
Ok to answer some questions, My shiva is in a 142 Liter box which is vented, 12 inch flared at both ends.
I've done some more testing and when i hold down the spider, the shiva makes a rattling noise, plus it doesn't seem to have the same amount of power, its very weak. Is this burnt voice coils?
I've done some more testing and when i hold down the spider, the shiva makes a rattling noise, plus it doesn't seem to have the same amount of power, its very weak. Is this burnt voice coils?
I assume that means a 12 inch long duct, not diameter, but in either event your box size is far too large for a vented alignment with this driver and that's why it was damaged; there isn't enough compression to prevent overexcursion. The noise you hear is the voice coil rubbing against the pole piece since the spider is no longer holding everything in alignment. The driver is irretrievably blown and will have to be reconed, which hopefully the manufacturer will do at no charge. Do not mount the repaired driver in that box unless you remove the duct and seal it tight.
BillFitzmaurice said:
This is one of the recommended sizes included in the Adire vented alignements. This is an EBS and should be fine if tuned at the correct point. Now if you model this however, a box of this size doesn't seem to perform as an EBS, and this has puzzled me for some time.
Now having a look at this in Subwoofer Simulator I can see how you could push this driver too far with that amp very easily. I've shown 25V which into 4 ohms is ~150 watts. As you can see it is pushed to xmax at about 27 Hz. It is more of a concern here than with the LFE use. (assuming rumble filter)
Here is a chart (output is into half space.) Excursion is also shown in red.
Attachments
I assume that your movie contained signals below the tuning frequency of the box. Under this condition the driver a vented box can be destroyed already at fairly low power.
You should add an active 4th order tschebbychef subsonic filter which
cuts all the signals below fb.
Good luck with Adire warranty!
Bye
Markus
You should add an active 4th order tschebbychef subsonic filter which
cuts all the signals below fb.
Good luck with Adire warranty!
Bye
Markus
The vented 142 liter box provides outstanding deep bass capability (flat to 20 hertz)
but the Shiva cannot handle much power in that enclosure.
Download Unibox and simulate it. You will see that you are in trouble in the
25 hertz to 38 hertz range, when 350 watts is applied.
In addition, the amp may produce even greater that 350 watts into the 4 ohm load.
Bill's box sizing statement is correct in terms of power handling capbility.
Choco,
Fb is 21 hertz in this aligment, so I don't think a subsonic filter will
help.
but the Shiva cannot handle much power in that enclosure.
Download Unibox and simulate it. You will see that you are in trouble in the
25 hertz to 38 hertz range, when 350 watts is applied.
In addition, the amp may produce even greater that 350 watts into the 4 ohm load.
Bill's box sizing statement is correct in terms of power handling capbility.
Choco,
Fb is 21 hertz in this aligment, so I don't think a subsonic filter will
help.
herm said:
This is a good thing. It means you don't need to spend too much on an amp to get the output limit of this driver as determined by the box and the driver VD. It may be a problem if there is more extension than desired at the expense of more output higher up, in which case an EBS design might not be appropriate.
herm said:
Where did this come from? According to the Adire paper, the Fb for the EBS is 18 Hz. Still, if you look at what happens to the excursion below Fb, you can see that a rumble filter should be worthwhile. I'd go with a steep filter like 36db/octave. There is one here (look under preamps)
BillFitzmaurice said:
Bill,
My simulations suggest otherwise - displacement limited power is higher in a vented box above tuning and in the ebs box, the sealed box will only have more power below 15 Hz.
In the simulation shown below, the power is 150 watts into 4 ohms and the sealed box runs out of excursion at 27 Hz. The vented box doesn't run out of excursion until below 15 Hz.
Now if the sealed sub had a LT to achieve a lower F3, then the output would become very limited ...
Weddie, what can you do in a nutshell?
Don't push your sub too hard!!!
1. If you can get it replaced under warranty, then just make sure that you have a rumble filter and be a bit more careful with the volume control. Get to know how much you can turn it up with movies - find the loudest deepest explosion you are likely to encounter and see what settings you can use without pushing your driver too much. Keep it so that p-p excursion is under an inch.
2. If you have to buy another driver yourself, then get something with more output and excursion. Consider the Stryke AV12 if you want a 12". You can put it in that box and it will perform as an EBS. With the AV12 you might have some excursion to spare even in a big EBS box. You might even consider a 15" driver, although in that box many will want it to be bigger.
>I took it out and check it, and i found that the spider had come loose. I was wondering if my voice coils are burnt and if so what should i do.
If the spider just came loose and isn't torn, you probably didn't over-power it. It just didn't get a good glue joint when it was built. If the spider is loose, lift it up and look at the coil. The coil should be sort of a shiny red color. If it is black, you burned the coil, but I doubt you did that. Typically the outer ends of the coil (top and bottom) would burn first since they are farther away from the steel top plate. In some cases you can just glue the spider back down and be on your way. I've done this before. However, if you held the spider down and played it and the coil scraped, this probably won't work, and I'd send it in for warranty.
If the spider just came loose and isn't torn, you probably didn't over-power it. It just didn't get a good glue joint when it was built. If the spider is loose, lift it up and look at the coil. The coil should be sort of a shiny red color. If it is black, you burned the coil, but I doubt you did that. Typically the outer ends of the coil (top and bottom) would burn first since they are farther away from the steel top plate. In some cases you can just glue the spider back down and be on your way. I've done this before. However, if you held the spider down and played it and the coil scraped, this probably won't work, and I'd send it in for warranty.
Thanks for all your help! Now if I can't get my shiva back under warrenty I will buy a different sub. Does anyone have any suggestions for a 12" sub that can handel 380 rms watts and would perform well in the EBS alignment, which is 142L with a 12inch dual flared port in 4inch diamenter. I can spend about $300 on this driver. If not, i'll go with the tempest with dual passive radiators, i heard good things about that setup.
Now if I can't get my shiva back under warrenty I will buy a different sub. Does anyone have any suggestions for a 12" sub that can handel 380 rms watts and would perform well in the EBS alignment, which is 142L with a 12inch dual flared port in 4inch diamenter. I can spend about $300 on this driver. If not, i'll go with the tempest with dual passive radiators, i heard good things about that setup.
I have a pair of the Mk III Shiva and recently built the same box using a straight 17" vent, but found the response not to my liking (XO at 80Hz). I have only ever powered mine with a Rotel amp bridged to 150W, and only ever use 1 voice coil, as I've never found the need for more SPL than this.
My suspicion is that your amp underperformed at 4ohms, or it could be set way too hot (do you have this calibrated with the rest of your system?), as you don't really 'hear' how loud it is playing XO'ed at 40Hz as you do.
With regards to my own box, I looked up the response from the Adire chart and found that it is quite low between 60-80Hz (not what I am looking for), and ended up capping the vent to get a sealed 142L enclosure. I'm much happier with this setup now.
I have the other Mk III sitting in a sealed 54L box.
My suspicion is that your amp underperformed at 4ohms, or it could be set way too hot (do you have this calibrated with the rest of your system?), as you don't really 'hear' how loud it is playing XO'ed at 40Hz as you do.
With regards to my own box, I looked up the response from the Adire chart and found that it is quite low between 60-80Hz (not what I am looking for), and ended up capping the vent to get a sealed 142L enclosure. I'm much happier with this setup now.
I have the other Mk III sitting in a sealed 54L box.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.