Author Topic: Triumvirate Build Doc Confusion  (Read 515 times)


  • Transistor Tickler
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Triumvirate Build Doc Confusion
« on: January 03, 2020, 06:58:20 PM »
Just got the Triumvirate PCB and have a couple of questions regarding some of the instructions and parts regarding the "fixes".

1) The "10F Cap Fix" - the text in the build doc says to use a non-polar 10F, but the grayed PCB layout on page 7 shows the use of a polarized 10F 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 F 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 10F 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 0.1F 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."


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Re: Triumvirate Build Doc Confusion
« Reply #1 on: January 05, 2020, 09:55:05 PM »
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.