chrisby
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A few random thoughts on this kit:
First of all, kudos to Steve for the considering it all, and subjecting himself to the gentle abuse in offering any Decware product based on a PCB. ::)
I guess you could consider that the actual cost of the PCB in the kit is a very small percentage of the total parts cost, and that this could be the cheapest way to accumulate the iron (most particularly custom OPT) and small parts, etc.
However, if trying to convert to tube rectification, or more importantly to a P-t-P build, remember that the cost of new tube sockets (the supplied parts will be for PCB mount), terminal strips, wire, etc, etc. could easily add another $50, not to mention the chassis. It appears that the mains transformer is the same as used in the production amps, so no additional filament transformer would be required if considering the addition of tube rectifier - just the mechanical & safety logistics.
As anyone who has attempted a clone of the Zen C amp (thanks to the very detailed schematics and build information contained on the site) will attest (you know who you are :-X ) - the costs can certainly add up on a one-off build, not to mention escalate when you start tweaking with boutique parts.
In an amplifier with a power supply as simple as the Zen (only 1 stage of RC filtering prior to the OPT tap), it's very hard to disguise the nature and flavor of the rectification. There are numerous accounts of tuning the Zen C and Select's character by rolling the "big glass".
Intrepid DIYers who have experimented with SS rectification in their tube projects ( aloha, all y'all Bottleheads) will know that not all "Sand sounds the same", and that swapping diode types from the basic 1N4007 can elicit some interesting changes.
Steve or others, - please feel free to correct me on the following:
Having been under the hood of a couple of Select amps in the past, my only concern with the current version of the kit is the substantial heat generated by the shared cathode bias resistor (and the 1K in power supply) . It would appear it ships with a 5W "sandstone" component for the first, and Mills W/W for the second, and while these may be adequate for the attendant current draws, I can remember the aluminum heat sink version the Select getting more than warm enough to melt the glue attaching the cathode resistor to the underside of the painted chassis. If not thermally sunk to a metal chassis component, I'd like to see these parts stood well above the PCB, well away from any heat sensitive materials (i.e. not at all near the "breadboard").
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