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Polk LSI25 Sub woofer amp Problem...Help!!

Hello Everyone! I recently acquired a nearly mint condition, or so I thought, pair of Polk LSI25s for $600. 

Everything worked well for 3 months, until today the Sub woofer on the right side started playing at what I think is max volume while listening to some jazz at a moderately low volume. 

While there are no inputs on the speaker, if I turn the sub woofer on it emits a sound that resembles that off a car muffler at a relatively low volume. Changing the volume knob seems to have no effect, but sometimes pressing on it can make the sound louder, or stop. 

It will still pass through music when connected, but only at what seems to be max volume. 

I live in Oklahoma and there aren't really any speaker repair shops near me. I'm quite savvy with computers and have taken the back plate off but don't see any type of burning issues or anything that looks out of place. 

Any suggestions? 
moskaudio
babyseaotter99
35 posts
 
I owned LSi25s for + years and probably replaced or had repaired, between the 2 speakers, the amps 5 different times.

I always dealt with Polk directly, but I think they are just a crappy sub amp. It's too bad because I really liked the look and sound of the LSi25s overall.

Average repair costs was usually around $100
moskaudio OP
28 posts
 
Yeah the sound is great. I managed to fix the amp on my own. 

I just took the back plate off and i think the board just has very weak heat dispensers. I pulled two transistors apart a little that looked like they had been moved closer together by heat induction, and bam. Fixed. 

I actually just purchased 2 Polk LSIM707s, 2 LSIM703s, an LSIM706C, and a Aventage 3070 from Adorama for $2800. The deal is still going. Got lucky and they all arrived in perfect cosmetic shape. 

Oddly enough though I still prefer the sound of the LSI25s to the LSIM707s. Maybe the need to just break in some more. 
moskaudio OP
28 posts
 
If not, I figure once the deal fades and Ebay settles I can always get my money back. Hell the receiver alone is going for $1,500 at the lowest at the moment. 
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