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Triumvirate Build Doc Confusion

Started by Cybercow, January 03, 2020, 04:58:20 PM

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Cybercow

Just got the Triumvirate PCB and have a couple of questions regarding some of the instructions and parts regarding the "fixes".

1) The "10µF Cap Fix" - the text in the build doc says to use a non-polar 10µF, but the grayed PCB layout on page 7 shows the use of a polarized 10µF cap. (I understand that the grayed PCB layout is updated and does not match the PCB I received. And that's OK. I just want to better understand the 10 µF fix. The text says the cap was a late addition to prevent any DC offset from being amplified thru the bass section. I get that. But considering the cap (C20 ?) is connected between ground and the 1K resistor (R4), it seems to me that a standard polarized electrolytic can be used with the negative leg connected to ground and the positive side connected to the 1K resistor. Also, the Shopping List on page 3 states in bold that the 10µF cap does not have to be bi-polar (NP). I'd just like to be clear on this point.

2) The suggested mod for the Treble Band Distortion - (not so much of question, rather a gripe) - this mod refers to R11 & C14. While locating R11 & C14 on the schematic is easy enough, locating them on the PCB requires some circuit tracing to locate. I could not see any obvious means of identifying R11 & C14 otherwise.

3) All of the 0.1µF MLCC cap locations are marked as "PWR" on the silkscreen. I found that rather confusing till I sorted it out thru the PCB layout image on the first page of the build doc.

Other than my whiny rants, this is a circuit I've been looking forward to building for a while now and truly appreciate all the great effort that went into creating the PCB and build docs. The mods are impressively noteworthy as well. I considered adding toggle switches to the clipping diodes in each section, but with space at such a premium in a 125B sized enclosure, I shall wait to do that in a second Triumvirate build in a larger enclosure and not mount the pots to the board.

Thanks for reading.
Cybercow - aka: Mark Davis

"Don't let your talent take you where your character can't keep you."

zgrav

in general, the documents are to be relied upon over the print on the VFE pcb, since some tweaking was done even to the finished VFE boad designs.  I think you are OK with a polariazed cap for the 10 Uf fix.    I also found the reference to the pwr capacitors confusing when I started building some of the VFE pedals, but at least that is a consistent part reference.