There is no need to use 2 of the 68uf caps on the one board. Only 1 of the two caps is responsible for the sound of the woofers. The other one is used for linearisation of the load for the amplifier.
Look at the circuit plan, you will see, that only 1 68uf cap is needed. To replace the linearisation cap with a MKP cap is a big waste of time, space and material... and money. It makes no difference for the amp using the cheap bipolar electrolyth cap in this position.
And there is absolutly no use of caps with 400V. The amplifier works with */- 40V, so 100V is completly sufficient. The Penta reaches it's 300W output with voltages less 100V. Usually caps with 160V fit perfectly with the size of the original caps. 400V does also not sound better, they are only more expensive. Since the boards become pretty warm, the heat dissipation can damage the caps easily, since there is less cooling space available. So it really makes no sense using 400V caps.
The pictures are still available in the old workbench forum how to replace the Penta caps...
Replacing the 27uf cap is also quite easy. On the original position fits a normal 22uf cap, on the other side of the pcb fits a 4,7uf flat MKP type perfectly. It is also better, using 2 caps instead of just one, the internal resistence becomes even better.
You can read it in the archieved forum from 2007...
