In 2008 I wanted a powered sub that could play at high volumes and keep up with my Klipsch Fortes and Hafler 500 amplifier. I was intrigued by models made by Pinnacle who opened in 1976 and were based out of Plainview NY. After some demos I bought the Digital 600 which retailed for $499. A surprisingly small 15" cube it fit easily next to my plasma TV and the solid brass isolation cones under each corner were a nice touch. It had deep response at high volumes and I found it very musical. Pinnacle subs were well regarded for years but as of 2020 I could barely find a reference to them online, they seems to have vanished. Recently I decided to open the sub up to see if it needed any R&R.

DIGITAL 600 SPECS
Compound Compression (isobaric) dual 12" woofers 2.5" voice coils, 50 oz magnets
600 watt amp
23-150hz response
108db max output
50 lbs weight

BELOW: The front grill pulls off without much difficulty. But the plastic frame is lightweight and can easily break in the corners. I broke mine and used Gorilla tape to repair the frame. No fuss. One 12" driver is on the front the other sealed deep in the cabinet.

BELOW: the electronics and heat sink are inset into the wood rear panel. Don't try to remove this panel, instead remove the entire wood back panel by removing the screws around the perimeter.

BELOW: this is the backside of the heatsink. The main power supply caps are 10,000 63V Gemcon. The blue pair are 220 35V NP. Several higher wattage resistors are situated above the board. From the unused holes in places it looks like this board was used in several different sub models. Everything was clean and tidy, no overheated parts or issues.

BELOW: the speaker wires attach to the board using locking spades. I wanted to replace the generic electrolytic capacitors but the board is glued down and the two large output transistors attached to the heat sink underneath at the factory...the board placed over them... and the leads soldered. The only way to pull up the board is to unsolder the leads in the center of the board first (see photo). It decided removing the board was too tricky and left it alone. To refresh the circuit I took my soldering iron and reflowed the connections on all the higher wattage resistors and contact points. I cleaned the crossover and volume trimpots.

BELOW: Pinnacle used a toroidal transformer which adds efficiency to the circuit. The heavy fiber-fill was too large and sloppily covered the basket on one side...reducing the internal volume. It had puffed out in another spot.

BELOW: I cut the liner mat shorter so it would fit the walls better and used a strip to fill the gap. I used some sticky Flex-fit tape to secure it.

• CONCLUSION: Doing basic R&R to this 15 year old sub was fun. I wasn't able to change out any parts on the board but reflowing the solder and correcting the fiber-fill were good modding tasks. Now the auto-on seems to start more reliably at low volumes and bass seems more musical.