What happened re: SVS PC Ultra grill issue?

indus · 15-11-2009, 9:07 PM

I remember some time ago some members raising issues with noises emitted from the grill of the pc ultra. What became of this?

I'm now know that this is a real issue. On certain scenes the grill on my pc ultra moves/resonates/flexes and produces a VERY audible noise. It is flexible, and therefore acts like a drum skin.
If I remove the grill, the noise goes, and I've checked this many times.

So, though I'm happy with the ultra on the whole, but would like a solution to this problem

Moonfly · 15-11-2009, 10:03 PM

Nothing was ever done AFAIK. My friend sent his back, and SVS pretty much dismissed it as a non issue. IMO, you need to make your own grill somehow, and replace the metal grill for a more traditional cloth one.

sammy the squid · 15-11-2009, 10:33 PM

yep, my cylinder went back. The service from khc was top notch and due to a change in personal circumstances, i never purchased the box. I think the conclusion was some people had issues with it and the majority didnt. Be interesting to see if any new svs cylinders adapt the same design or if its modified.

stevefish69 · 15-11-2009, 10:34 PM

I did PM KHC with regard to this but never had an answer.

TBH i've not heard the noise for a long time whilst watching a film so i've not bothered to pursue the problem even though i know it does exist though at uber high SPL. I get a similar noise from the grill's on my Kef Ref's although this is much worst. I now remove the Kef grill's when i know i'm gonna watch an action film.

Not the correct answer (for a £2.7K pair of speakers), but it works and takes all of 30 seconds to do. If the SVS starts rattling again, i'll probably just do the same

Legzr1 · 16-11-2009, 12:53 AM

I get the same problem with my 4.2's - a little bluetac in the holes where the grill mounts really does help (as does removing them in the first place

).

The grill on my PC13U is fine.

However,at very high SPL I get vibrating floors upstairs,rattling windows and wobbling doors

jameslunn · 16-11-2009, 9:04 AM

I've had this issue in the past and it did it again watching Star Trek at the weekend.

I thought about getting some good strength fishing wire, putting a weight on the end, dangling it down one port, then hooking it back up. Basically down one tube and up another. Once I've got both ends, thread them through the grill and pull the metal down tight, this should stop it from flexing. Boy Scout knots required...

Any thoughts?

Cheers

James

Moonfly · 16-11-2009, 11:59 AM

Quote:

Originally Posted by jameslunn

I've had this issue in the past and it did it again watching Star Trek at the weekend.

I thought about getting some good strength fishing wire, putting a weight on the end, dangling it down one port, then hooking it back up. Basically down one tube and up another. Once I've got both ends, thread them through the grill and pull the metal down tight, this should stop it from flexing. Boy Scout knots required...

Any thoughts?

Cheers

James

Honestly?

Terrible idea. Anything in the ports will only make4 the air more turbulent and increase issues. Most of the problem with the grill is not rattle, its simply air being forced through the tiny holes at such a rate the air movement becomes audible. The only solutions to this is a grill with larger holes, some kind of vent to prevent pressure build up behind the grill, or another grill entirely, like a cloth one.

Edit:

Oh BTW James, I'm going getting my drivers for my DIY sub next week, so I should have something ready in a few weeks. You still up for a testing day?

jameslunn · 16-11-2009, 1:00 PM

Yeah - defo still up for the test day, no worries.

Re the PC13, I disagree, for or me it’s not the disturbance caused by air passing through the holes, it’s the flexing of the metal mesh. It moves from one static state to another under heavy loads, like a diaphragm. I doubt fishing wire will have any effect on the air-flow, but will stop it from flexing.

I will give it a whirl and report back, worth a go, I can always remove it.

Cheers

James

indus · 16-11-2009, 1:15 PM

Thanks.

As others have said its not the end of the world and on the whole I'm happy with it. It seems to happen for me on a few certain scenes of Ironman.

I agree with James though, the sound is due to the grill flexing/unflexing not due to sheer volume/speed of air passing through (imho

)

Moonfly · 16-11-2009, 2:11 PM

I look forward to your results then guys. I never noticed grill flex myself, but perhaps it creeps in with age a little, not sure

Nimby · 17-11-2009, 11:30 AM

Isn't it half the problem that you are too busy enjoying the film to worry about grill noise? You chaps just aren't taking this matter seriously enough! Has nobody done any serious research into the this?

I like James idea except for getting sufficient tension in only one direction to kill any "drumming".

A screw and spacer into the top plate between the ports on the PCU would be more efficient if the grill really was vibrating like a diaphragm. Downside is you've made a new hole in the grill if you should ever want to sell it. Use a long, thin countersunk screw and paint it black and it wouldn't notice. Call it an upgrade and charge extra?

What about a screw and spacer underneath the grill which lifts the grill slightly. Just enough to tension it a little? No extra holes required in the grill.

A suitable rubber ball under the grill resting between the ports and lifting the grill slightly? You could rest a ball in one of the ports if you usually have one closed just to tension the grill slightly.

Don't drop a spacer or ball down one of the ports though! Hard rubber, aluminium or stiff plastic tubing seems most practical for a spacer. Steel might stick fast to the magnet if you drop it down a port! You'd have to dismantle the base plate and remove the driver to get it back.

stevefish69 · 17-11-2009, 3:50 PM

Personally with my PCU it's just the whistling noise through the holes so no amount of damping is going to help. It only comes into play at around 115db so i'm personally not too bothered as the house makes more noise / creaks than the PCU at this SPL.

In all honesty Nimby my problem is not that bad. Maybe it's because the EQ1 has worked it's magic. There are now no pesky peaks in my room so the output across some of the frequencies are reduced to make up for the room gain

Maybe if the Sub was not EQ'd in any way then the PCU would be outputting maximum SPL across the board as per design. This would explain why some users hear different symptoms with regard to grill noise and chuffing

jameslunn · 24-11-2009, 10:10 AM

Gents,

I've installed a work around for this that is dead simple. It's been installed since Friday evening and seems to be working well. Its something that all PC13 Ultra owners can do in 30 seconds and looks quite good too.

Will post some picks and hopefully some video (before/after) too.

Cheers

James

Legzr1 · 24-11-2009, 2:54 PM

You just removed the grill didn't you?

**IronGiant** · 24-11-2009, 5:28 PM

He's hoping to rack up the suspense a bit longer...

jameslunn · 24-11-2009, 9:22 PM

Gents,

Its dead simple really...

Take one sharp knife.

And one SVS Ultra Bung and chop 2cm off the bottom.

Place the 'Mod Puck' in the middle of the unit, between all three ports.

Replace the lid.

You end up with this...

YouTube - SVS Mod.m4v

Cheers

James

sammy the squid · 24-11-2009, 9:37 PM

well illustrated James, some handy knife work there to

Would be interesting to hear it in person to.

Regards

Sammy

jameslunn · 24-11-2009, 9:51 PM

Cheers Sammy,

It makes quite a difference.

Well if you're ever in Yorkshire, PM me and come and have a listen.

Cheers

James

kbfern · 24-11-2009, 9:59 PM

The simplest solutions are always the best

SBanga · 24-11-2009, 10:15 PM

Nice mod and a fellow Leeds PCU owner. Good man

sammy the squid · 24-11-2009, 10:17 PM

thankyou kindly for the offer James, im only in lancashire so may well take you up on that offer in the future

Regards

Sammy

indus · 25-11-2009, 10:14 AM

Thanks James, that will work. The grill flexes in the middle where there is no support, this should fix that.

Perhaps SVS should incorporate this in future and pay you a small royalty

kbfern · 25-11-2009, 10:44 AM

Just done the mod to my PC+ as I have noticed a bit of Tizzing at high volumes.

AngelEyes · 25-11-2009, 11:42 AM

Great British engineering, well done

Adam

jameslunn · 25-11-2009, 12:26 PM

I sent the vid and a link to the thread to Ian at KHC and he said 'Love the “Puck” concept. I’ll pass on to the SVS boys to see if they’ll manufacture them?'

Lets see what happens. No royalties required... but a complimentary secondary PC13 wouldnt go a miss... obviously for research purposes and further mod development...

J

tin69 · 25-11-2009, 1:48 PM

Great mod

Hail Sir jameslunn ...

stevefish69 · 06-12-2009, 11:59 AM

Great mod - Finally got off my arse and spent 30 seconds doing my this today. Just been playing Bassotronics at Ref level with the power amp off so that just the Sub was playing and the only spurious sounds now are those poxy picture frames rattling all over the house.

I might posty my own 30 second mod which involves a pack of Blu-Tac sticking everything down around the house that rattles