PCi+ bottoming out???

[patnshan]

Hi Guys,
I had an unpleasant experience the other night while watching Nim's island in DTS lossless Blu Ray on my PS3. The soundtrack is really good, but during one of the major storm scenes I heard an aweful noise from my sub. I think it bottomed out. We were watching it at about -10 and the sub is calibrated about 5 dB hot. I have watched movies like transformers, Das Boot, etc. at higher levels than that and have never had that happen. I listen to Rock music, Rap, R&B with heavy bass with no problems either. I am not sure why it did as I think I have a pretty powerful sub.
It seems to sound good now. What do I need to do to check the sub for damage?
Should I recalibrate it to make sure the settings didn't get changed inadvertently?
I am a little disappointed as the Plus has handled everything I have thrown at it in the past and am worried that I now need to take it easy.
Thanks,
Pat

 

[mike c]

cough* ultra cough*

maybe you can request a waterfall chart of the specific scene from the avs waterfall thread to see what really is going on.

a 20-31, wow - i just found out today that there was 20-31 PCi, now there's a plus too!

if it sounds fine now, it "should" be ok. try the same scene at a lower volume and see what happens?

 

[j_garcia]

Having enough power won't prevent the sub from bottoming out. That isn't distortion that is it moving beyond its physical limit. Not to mention, I would think it is a greater possibility with it in 20Hz tune in that enclosure. I would ask SVS if you need to worry about it or if you need to take it easy.

 

[GlocksRock]

Bottoming it out one time won't hurt it, I've bottomed my 20-39PC+ a couple times and it's still fine. As long as it still sounds like it did before you bottomed it out, everything is ok with it. However you may want to consider upgrading your sub.

 

[patnshan]

Thanks guys! I didn't take note at the exact point in the movie, so maybe I'll watch it again and see where it is. I'd like to know the frequency of that scene as well.

Mike, my 20-31+ is just the 25-31+ with one port plugged and the tune switch moved. When I talked to SVS about my setup, they felt the 20 Hz tune would work just fine. I doubt I am pushing it too hard at 10 below reference I think I'll give them a call next week.

Thanks,

Pat

 

[patnshan]

Bottoming it out one time won't hurt it, I've bottomed my 20-39PC+ a couple times and it's still fine. As long as it still sounds like it did before you bottomed it out, everything is ok with it. However you may want to consider upgrading your sub.

I wanted the 39 incher but my wife "strongly recommended" the 35 incher. I am gonna keep the sub for now as I need a couple new displays first I think I may have to run it a little less than 5 Db hot

Pat

 

[j_garcia]

Once or twice probably won't hurt it, but I'd definitely turn it down if it keeps happening. Based on the other stuff you watched without issue, I'd say you will be OK.

 

[Midcow2]

What causes bottoming out?

Once or twice probably won't hurt it, but I'd definitely turn it down if it keeps happening. Based on the other stuff you watched without issue, I'd say you will be OK.

This may be a dumb question, 'But what exactly causes bottoming out ?'

I assume this is too much signal level, but since most subs are active rather than passive, meaning the sub supplies the power amp and shouldn't it be the right size.

Does this mean you have too hot of a pre-out signal coming into the sub?

What really scare me is that it is happening to an SVS sub, which SVSs are some of the best!.

Anyway, thanks fro oyur patience in answering my question

 

[mazersteven]

I think I may have to run it a little less than 5 Db hot

I don't know why you feel the need to run your sub hot. If you don't have enough out-put maybe it's time for an up-grade. For what you could sell your sub for a PB12-Plus/2 wouldn't be much out of pocket.

 

[patnshan]

I don't know why you feel the need to run your sub hot. If you don't have enough out-put maybe it's time for an up-grade. For what you could sell your sub for a PB12-Plus/2 wouldn't be much out of pocket.

The only reason is that I like the bass a slight bit more powerful than matching levels all around. If it happens again I will most certainly look into a larger sub. It is quite a big room. The other thing I could do is take it back down to 25 Hz, giving myself more headroom. Do you think that would help?

Pat

 

[GlocksRock]

This may be a dumb question, 'But what exactly causes bottoming out ?'

I assume this is too much signal level, but since most subs are active rather than passive, meaning the sub supplies the power amp and shouldn't it be the right size.

Does this mean you have too hot of a pre-out signal coming into the sub?

What really scare me is that it is happening to an SVS sub, which SVSs are some of the best!.

Anyway, thanks fro oyur patience in answering my question

Bottoming the sub out happens when it reaches it's mechanical excursion limits.

 

[annunaki]

This may be a dumb question, 'But what exactly causes bottoming out ?'

I assume this is too much signal level, but since most subs are active rather than passive, meaning the sub supplies the power amp and shouldn't it be the right size.

Does this mean you have too hot of a pre-out signal coming into the sub?

What really scare me is that it is happening to an SVS sub, which SVSs are some of the best!.

Anyway, thanks fro oyur patience in answering my question

The bottoming of a subwoofer is when the woofer is exceeding mechanical limits. This tends to be a loud cracking or clanging noise. The voice coil former slams into the back plate or the spider/neck joint slams the top plate/polepiece/spider mounting platform. Here is a diagram of the internals:

Sub woofer anatomy

Bottoming can be caused in a number of ways.

1. Over powering of a woofer that is suspension/mechanically limited rather than motor limited. Essentially the motor structure can drive the suspension to it's limits and beyond.

1a. "Bottom less" woofers are motor limited (in most cases) meaning the motor runs out of force before the sub can reach its mechanical/suspension limits to prevent damage. This is very popular in today's designs.

2. Playing a woofer below the tuning frequency when in a vented enclosure.

3. A combination of both 1 & 2.

A woofer bottoming out can cause damage even on the first occurance depending upon how tight tolorances are within the woofer's workings. Many woofers will be fine with a single occurance but others may experience damage.

 

[Midcow2]

So you want really, really LOUD ??

Bottoming the sub out happens when it reaches it's mechanical excursion limits.

Which is the end result from too much electrical excitation of the speaker solenoid caused by too high output from the sub self power amp caused by too high of pre amp input signal caused by running the sub pre out at +5 dB when the ambient SPL is ay 105dB. ---- I GET IT

So the real answer is to get a SVS- PB13-Ultra and if that doesn't work get two SVS-PB12-Ultra and if that still doesn't work get one, then two JL Audio FATHOM f113s and if that doesn't work get the JL Audio GOTHAM g213 at $12,000 MSRP and a net weight of 360 lbs.

 

[mtrycrafts]

Thanks guys! I didn't take note at the exact point in the movie, so maybe I'll watch it again and see where it is. I'd like to know the frequency of that scene as well.
Mike, my 20-31+ is just the 25-31+ with one port plugged and the tune switch moved. When I talked to SVS about my setup, they felt the 20 Hz tune would work just fine. I doubt I am pushing it too hard at 10 below reference I think I'll give them a call next week.
Thanks,
Pat

How many such storm scenes are there in the movie
but during one of the major storm scenes
Perhaps it is easy to find? Also, may want to use an spl meter in that section as well.

 

[mike c]

Mike, my 20-31+ is just the 25-31+ with one port plugged and the tune switch moved. When I talked to SVS about my setup, they felt the 20 Hz tune would work just fine. I doubt I am pushing it too hard at 10 below reference I think I'll give them a call next week.

ack. brain fart on my end. i was thinking about the re-tuned ports of the PCi.

What really scare me is that it is happening to an SVS sub, which SVSs are some of the best!.

it can happen to any sub actually.

I don't know why you feel the need to run your sub hot. If you don't have enough out-put maybe it's time for an up-grade. For what you could sell your sub for a PB12-Plus/2 wouldn't be much out of pocket.

i think i just saw that the plus/2 at SVS is all out

The only reason is that I like the bass a slight bit more powerful than matching levels all around. If it happens again I will most certainly look into a larger sub. It is quite a big room. The other thing I could do is take it back down to 25 Hz, giving myself more headroom. Do you think that would help?

Pat

i was asking SVS about the 20-31 PCi, and they said tuning it that low does not affect headroom at the upper bass because it was amp limited at 300+w.

but yours i think has the 500+w amp - so i don't know if it applies.

but it might just have been caused by too low a frequency at too loud a volume - if you do play around, do try the 25hz tune as well at the same volume.

 

[croseiv]

I've yet to bottom out out my PB-13 U. You should get one. Also, what does -10 equal relative to the level you calibrated at? In my system that would be very loud as I am calibrated at -15 which equals 72 dB (running my sub 3 dB hot=75 dB). Any peaks will easily add 15 dB to that (DTS tracks maybe even more). Just turn it down....or get another sub or two...

 

[Bluesmoke]

Which is the end result from too much electrical excitation of the speaker solenoid caused by too high output from the sub self power amp caused by too high of pre amp input signal caused by running the sub pre out at +5 dB when the ambient SPL is ay 105dB. ---- I GET IT

So the real answer is to get a SVS- PB13-Ultra and if that doesn't work get two SVS-PB12-Ultra and if that still doesn't work get one, then two JL Audio FATHOM f113s and if that doesn't work get the JL Audio GOTHAM g213 at $12,000 MSRP and a net weight of 360 lbs.

That is so ingenious and look at the small footprint. If I was rich, I'd have 4 of those in each corner of my room.

 

[patnshan]

How many such storm scenes are there in the movie
but during one of the major storm scenes
Perhaps it is easy to find? Also, may want to use an spl meter in that section as well.

There are actually like three, it was the first one I believe.

Pat

 

[patnshan]

That is so ingenious and look at the small footprint. If I was rich, I'd have 4 of those in each corner of my room.

Hey, I think one of those may fit where my plus is now

After those two displays I need, maybe I need to stuff one of those in back of the couch. Maybe she won't notice. How much cash do I need to hide?

Pat