Fearlessly Fixing The Blodgett Family Room Speakers (Paradigm UltraCube 10 Sub & CC150 Center Channel) 15Jun22-05Jul22

With an awesome new 42" OLED panel in the Blodgett Family Room spot, I set out to repair the associated 5.1 speaker setup there. Unfortunately the subwoofer (Paradigm Ultracube 10) is ~20 years old and it just recently stopped working completely after a year of sounding a smidge suspicious. Further, the center channel (Paradigm CC150) is also 20+ years old and an old repair of the foam rounds I did some time ago has again failed. The speaker is going "blaaaapppp." Someone more sane than I would probably just choose some new speakers, drop the K-buck, and re-install. While I may have to go there ultimately, I first will attempt to repair the fails more directly on existing speakers. Now for the sub fail and repair... I disassembled the subwoofer (all the drivers are fine) and went online to determine the most likely cause of its failing.

The most common failure is the power amp portion of the 1200w plate amplifier built into the sub - and in that there are a number of capacitors that fail or go out of suitable range for the power circuit. I acquired a schematic and determined which caps were more likely to be buggering the works. I also had to acquire an LC meter (to measure inductance and capacitance). There was a cheap $40 one on AMZ which folks said was fine - and was surely good for me versus the next closest ~$200 competitors; Fluke's entry was $400+ and I still got gray wrapped by yellow. In the day we used to prosecute even color IP disturbances.

I measured the possible problematic capacitors against original specs in the power supply, power amp, and pre-amp. Kala liked the geeky image - $15 magnifying headset is a godsend.

Here are the results; a number of 22µF and 10µF caps were out of spec so I found substitutes, ordered them, and replaced the seven critical ones. One guy just comprehensively replaced every one in the circuit. It was not a big purchase because the BOM is actually pretty friendly with mainly 22µF and 10µF caps! I'd hoped I'd not need to extend the repair to all caps.

Bench desoldering and removal of old caps was a task from hell (the solder on this board was problematic) and suited only to completion with a powerful solder sucker and under my magnifying glasses again, with much tedium. Nonetheless, accomplished. Resoldering new caps in was a smidge easier 'cause the through holes and pads were cleaned up from my prior actions. Next, a smoke test... I just powered it up while still disassembled to see if it would blow up, and see if a signal would move the driver. A simple 60Hz grounding sound showed all seemed right. This whole process was a very long shot fix ~ but it worked! For ~$60 (including the LC meter) and 1.5 days net time I brought this $1200 sealed sub back from the dead! It's buttoned up and back in place. If it fails again though, I will probably drop the $500 on a new small sealed SVS sub. I respect the EE rework station bench techs and have hand burns to prove my ineptitude.

Now on to the center channel. I disassembled the Paradigm CC150 too and physically measured carefully. I didn't want to just replace the foam rounds as I had before; I wanted to replace the entire mid-bass drivers with new transducers. No exact replacements from Paradigm (who makes their own drivers) were available. After a morning of searching, and soul searching (as there were "nicer" drivers I found that might work very well), I chose to buy some relatively cheap Dayton Audio drivers which would hopefully fit the cavity and fit the bill. I didn't buy better Taiwanese Tang Band drivers because replacement cost of an entire unit could be had for just ~$250 (not perfect but acceptable) and so buying $140 worth of drivers seemed too much; ~$60 was better.

The replacements were on backorder but after they came in early July I installed them and the fit was nearly perfect. The front cover doesn't fit any more but that's no problem as the speaker hides behind a sonically transparent panel I made originally when we moved into Blodgett. So, driver cost plus a <1/2 day's time on the center channel was the investment.

Of course after a new set of drivers in the center channel and a repaired sub I wanted to remeasure the area to configure delays & frequency responses. The Yamaha RX-V2700U AV receiver has that capability built in so after researching how to use the feature again, and finding the measurement mic, I did so and the family room theater is again sounding solid.  The CC looks a lot better than the nasty foam rim repair I did prior.

UPDATE 07Jul22... Unfortunately the subwooofer fix didn't last. It blew again. And, true to my word, I did not repair it a 2nd time. Instead I ordered & installed a new SVS SB 1000. It's a sealed sub like our last one (as they tend to have a tighter response in general, IMO). Re-EQed and sounding stellar. This was delivered in one day via AMZ and is recommended. All is said and done, and measured... good response to my house curve.