Sunfire True Subwoofer MK II Loud Thump

[aholloway17 23]

Hi all, 

 

I just added a pair of B&W CM5 S2 speakers to my set up. While trying to balance the sub, it seems to have developed a significantly loud thump? This particularly occurs when playing a track with a good bass line and at any level as long as the volume up so the music is audible. This seems to occur every 4 to six beats. Not only is it audible , but if I put my lightly on the driver, I can feel it hit really hard. Up until I tried to balance the  sub with the new speakers, it never displayed an off sound. I've had it for twelve years. I've switched outputs from the Sunfire Tubed Preamp, cables, and unless I turn the volume all the way down it occurs. Adjusting the crossover setting yield no change.  And no, it doesn't matter the song, one I've played for years or a new one.  Should I be looking at the preamp? Because that plays smoothly if the sub isn't on. 

 

Thoughts?

 

Cheers,

 

[BillWojo 542]

I had an issue like that and it turned out that the spider had come unglued in the driver. Not an easy fix.

 

BillWojo

[aholloway17 23]

Lol, I take it the spider help hold something together but I've no idea what!

[AndrewJohn 10,708]

The speaker cone is suspended on the outside edge by the "surround", and is centered and supported in the inside center edge (hole) by the "spider" also sometimes called the "suspension".  You don't usually see it unless you look through the "basket" or frame of the speaker's housing.  The "spider" is attached to the "former" around which the voicecoil wire is round.  The spider is designed to allow in and out movement as the cone moves air (creates sound) based on the electrical signal sent to the speaker from an amp.  Here's a few pictures.

 

 

 

Here's a torn or separated spider repair video...  I don't know what the issue is with your sub, just wanted to share some links to clarify what the spider was, and how it might fail.

 

 

[aholloway17 23]

Wow, that is a great explanation! And something I will never try to fix on my own. As my sub is at least 12 years old, it's time for a tune up by a qualified technician! 

Thanks a bunch!

Edited August 6, 2020 by aholloway17

[EAHBuckeye 238]

On 8/3/2020 at 7:34 PM, AndrewJohn said:

The speaker cone is suspended on the outside edge by the "surround", and is centered and supported in the inside center edge (hole) by the "spider" also sometimes called the "suspension".  You don't usually see it unless you look through the "basket" or frame of the speaker's housing.  The "spider" is attached to the "former" around which the voicecoil wire is round.  The spider is designed to allow in and out movement as the cone moves air (creates sound) based on the electrical signal sent to the speaker from an amp.  Here's a few pictures.

 

 

 

Here's a torn or separated spider repair video...  I don't know what the issue is with your sub, just wanted to share some links to clarify what the spider was, and how it might fail.

 

 

AndrewJohn, what great info! I believe I may be dealing with a broken spider on my SF TrueSub Jr. I only hear it if I'm playing very bass heavy tunes loudly, but it sounds similar to the one in the video you posted. I need to open it up to be sure, but I second aholloway's comments, don't think I'll trust my lack of skills for the repair.