Klipsch Forte II Passive Radiator stuck vibrating

[Jarrod]

I have a used set of Klipsch Forte II speakers I picked up last year.  I have always enjoyed Klipsch speakers and always wanted a pair (I still run KG4's in my living room) .  They sound excellent at most volumes but when I push them hard the passive radiator gets stuck vibrating and causes a terrible low rumble noise.  For example if I play side two of Dark Side of the Moon at the end of the album the vibration noise is very audible and when the music is over the passive radiators continue to vibrate and cause the loud low rumble noise until I lift the needle from the record.  Just the background white noise of the needle on the record with no music is enough to keep the passive radiators stuck vibrating violently.  Almost anything Led Zepplin at only moderately high volumes causes this as well.  It ruins the ability to listen at high volume which is one of the reasons I got these speakers.

 

My set up is as follows (yes i pulled out my old equipment when I bought the speakers):

 

Onkyo Direct Drive Turntable CP-1130F with ST XLM II Cartridge

Denon DRA-425R Receiver

Klipsch Forte II (from 1995)

 

Is this an issue with the Forte II's at high volume?  Is there anything that can be done?  The speakers themselves sound great and at lower volumes everything works fine.  

 

Any thoughts, suggestions or help would be appreciated.

 

Thanks!

[jimjimbo]

Both speakers or just one?  Disconnect one of them and listen.  Are you sure that they are fully secured in the cabinet?  No rips or tears or?

[Jarrod]

 

1 hour ago, jimjimbo said:

Both speakers or just one?  Disconnect one of them and listen.  Are you sure that they are fully secured in the cabinet?  No rips or tears or?

 

Both speakers do it, there are no rips or tears.  Everything looks good and is secure.  

 

Ok, I disconnected one speaker and when I run just one speaker it does not cause this issue.  One speaker by itself works and sounds great.  When I connect both speakers the issue comes back.

 

Is this something you have seen before?

Edited September 1, 2017 by Jarrod

[jimjimbo]

I have no direct experience with  this specific issue, but it just sounds very odd....pardon the pun.  The passives have no electrical connection and are volume and placement dependent.  Can you possibly send a photo of the setup, and of each passive as they are currently configured.  You have verified that when you disconnect the left that the right works and vice versa?

[djk]

You need a steep filter to remove all the junk below 30hz from the phono.

 

Something like this will do:

 

http://www.ebay.com/itm/Vintage-Audio-Control-Stereo-Octave-10-band-graphic-equalizer-subsonic-filter-/253104489715?hash=item3aee3404f3:g:Ro4AAOSwP0ZZjF8b

 

http://www.ebay.com/itm/AudioControl-D-520-5-Band-Equalizer-with-Subsonic-Filter-and-Tape-Monitor-/322665374596?hash=item4b205ae384:g:HvcAAOSw~iRZmgN3

[WMcD]

This is by no means a fault in the speaker. The passive radiator, and the main woofer which drives it, can not oscillate for a long time as describe unless the amp is sending it a corresponding signal.

it is not entirely clear what the situation is.  If this oscillation is occurring while you have the stylus is in a seemingly silent groove and the disk is turning,   it is possible that the source is "rumble" from the turntable motor.  

Otherwise, it is coming from the amp.  Under some circumstances the amp can oscillate and this was in the old days called motor-boating because of the low freq growl.

Another possibility is an acoustic  feedback loop between the speaker and the stylus.    We hear this as a high freq howl when a microphone is too close to a speaker.  But it is possible to get a low freq equivalent with a turntable.  This is why people use isolation pads under their turntables.

Tell us more.

WMcD

 

[pzannucci]

Sounds like you are using vinyl and way too much vibration at high volumes.  Since the Forte will go rather low,as said above, this is a feedback situation.  If you have tubes in the mix, like a preamp and vinyl, then you could also be adding microphonics into it.

Hold you hand on the base of the turntable and or tonearm after the loud passage, it will point you in the area.

[unclefred]

I've had the same issue with subwoofers  when the TT was not isolated properly. It can sometimes r\also require isolating pads under the system rack. 

[Jarrod]

Hey everyone, sounds like I a have a few things to try here, specifically isolating the turntable to start with.  I have been away for the holiday weekend and have not had time to try anything yet.  I will try to get some time when my wife and kids are out of the house over the next few days and report back.

 

Thanks for all the responses and suggestions, this is a great group!

[Jarrod]

Hey Everyone,

 

So turntable placement and adding some pads under the turntable fixed the issue.  I tried a few places in the room and found I needed to have the turntable farther away from the speakers, but not in a corner of the room.  Putting the turntable in a corner of the room when it was even farther from the speakers actually made it worse.  

 

As someone mentioned above putting my hand on the turntable base temporilary calmed the issues when it was occurring.  I found a place in the room for the turntable where the issue is now completely gone.

 

Thanks to everyone for the suggestions and help, I really appreciate it!

[unclefred]

Glad to here that. TT's can be tricky.