[CraigPSB]

Hi All,

New to the forum.  I have a PSB C6i center channel speaker that was sounding boxy.  This speaker has two 6.5" woofers with two 1" stacked dome tweeters.  Upon inspection it appeared the top tweeter was not working, which would certainly contribute to the boxy sound.  But upon wiring each tweeter individually the top tweeter does work, just not at the same volume as the bottom tweeter at the same volume setting.  Both measure 4.9 ohms at the terminals.  I recapped the crossover to no avail.  I would simply buy new tweeters from PSB but of course they no longer have these available.

What would cause the one tweeter to play at a lower volume being the coil is the correct ohm value?

[mgalusha]

Hard to say for sure, but if they are ferrofluid tweeters, possibly the fluid has changed in one of them. That is a total swag, but a possibility.

[richidoo]

They are ferrofluid.

https://audiokarma.org/forums/index.php?threads/the-ferrofluid-dilemma-fact-or-fiction.757847/

[jonbee]

Ferrofluid thickens up over time, and even moreso if overheated by overpowering the tweeter, sometimes turning into a solid. There are shops that can repair this kind of problem. You might check for a referral from PSB or watch ebay for promising looking parts. DIYaudio.com has a lot of knowledgeable guys, too.

[CraigPSB]

Hi,

I recently posted regarding this center channel speakers tweeters playing at a lower than normal volume, causing a boxy sound.  Since then I used my Anthem ARC program to measure the frequency response to make sure I wasn't hearing things.  Turns out what I heard was correct, a steep drop-off after 2K Hz, which is where the speakers crossover frequency is.  Since PSB no longer makes these tweeters I searched for a replacement.  Since the PSB uses a custom faceplate, and has a low 2K crossover my options were limited.  I found a Peerless tweeter (DQ25SC16-04) that does come with a faceplate, but the tweeter itself is simply glued into the plastic faceplate, and looked to be the same size as mine based on the spec sheet. It had a freq. response that was acceptable.  I took a chance and ordered two.  I cut the faceplate away with a dremel and removed the tweeter.  After sanding down part of the tweeters plastic body and modifying the PSB faceplate mounting, they fit like a glove.  I fired it up and wow, no more boxy sound !  I thought I might need to mess with the crossover to match the levels of the tweeter and woofers, but it sounded great as is.  You can see the difference in response below between the originals that were no longer working properly, and the new ones.  I did take apart one of the originals and the ferro fluid was dried out and had turned into a brown spiky substance. 



Freq Response with Original Tweeters (Pink Line)



Freq Response with New Tweeters