A search through the parts bin in the PTP Audio workshop soon resulted in everything necessary to assemble a gainclonish amplifier. As with many hobbyist projects, the most fun was the construction itself. Whether the outcome would grow in status and gain a stay-around permit was to be seen or in this case, auditioned. What Peter heard from his breadboarded contraption was a revelation for what really is a - well, dieheart tube guy. Not long after his initial encounter with the opamp’s potential, the real deal began to take shape. Parts were swapped for better ones, the layout was refined, the power supply beefed up. Of course the visual appearance enjoyed plenty of its own considerations too and from the very start of the maturing phase, it was clear that the casing should be Corian, the typical PTP Audio building block for all of their turntable plinths.


After quite a few iterations and many many hours of listening, the Blok20 emerged. The production version became a very minimalist integrated solid-state amp. The gain/buffer stage consists of one op amp and three resistors per channel. Built as a two-story affair, the basement is occupied by a hefty 300VA toroidal transformer. All rectifiers are ultra-fast recovery types, all connections point to point. Where wire is unavoidable, it’s silver-plated copper in Teflon dielectric. There are three single-ended inputs with a Z-in of 50kΩ each. All parts are fitted in a housing CNC’d from a block of Corian measuring 17x17.5x20cm HxWxD. PTP Audio fancy white and black Corian as stock colours but any available color of Corian may be ordered. Du Pont even advertises that Corian can be fabricated in any colour imaginable.


When Peter asked if we were interested in reviewing the finished Blok20 amplifier, we agreed instantly. Not long after he returned with a Blok20 production sample in gloss white. For such a small block, the weight of 8kg surprised us. Its front is as minimalist as the circuit inside. Only two knobs situated at about 2/3rd of the total height bracket a sunken-in red power indicator somewhat lower on the facade. At the back things are just as simple. The black-anodized aluminium panel leaves two open vent slots for air exchange and doubles as heat sink for the mounted op amps. The three sets of RCAs are nicely spaced and occupy the top half of the back plate. Above the IEC connector with the mains switch and fuse bay sit the loudspeaker binding posts.


Whilst spacing between the inputs is generous, the spacing between the binding posts and more particularly the two negative terminals and the IEC connector socket is a bit narrow. With spades and a chunky IEC housing, some creative adjustments will be necessary. Bananas work like a charm however. Peter recommends to leaving the Blok20 powered up at all times. Idle consumption is very low and as with most chip-based electronics like DACs and this amp, optimal performance is obtained when things aren’t powered off.