trinityamps.com

Hello All - I received my Trinity plexi kit yesterday and have already got busy with some initial assembly - I am pretty stoked

I've looked at a lot of different amp builds (not just 18 watt) over the past few weeks checking out layout and lead dress - how wires are routed, grounding etc. and was hoping a few of the gurus might chime in on my questions.

It is suggested in the Trinity manual to knock off the layout exactly in terms of lead dress. But.. I assume that the drawing is also laid out to be easy to read as opposed to an actual "perfect" lead dress layout - correct?

1. For example: the shielded cables from the input jacks are shown routed indirectly around the outside perimeter of the chassis to the tube sockets, yet nearly every amp I have actually seen seems to just randomly lay shorter lengths of shielded cable over or under the board in a more direct line to the tube sockets. I would assume that because these cables are shielded that they could simply be laid in a somewhat careless fashion. Or am I incorrect, and should I indeed rout them around the edge of the chassis in spite of that increasing the length of the cables?

2. Some wires are shown bending in pretty specific shapes, crossing other wires perpendicularly etc - From what I read this is often intentional to avoid interference and other electrical issues. For example, on the layout drawing the wires from V1 and V3 on pins 7,8,9 all bend in a specific path as well as cross each other at right angles, maintain certain spacing that seems intentional in the drawing - is this positioning and routing for lead dress purposes, or just to make the drawing easy to read and follow, or a bit of both?? Are there specific wires one should be particularly careful with vs others? say from certain tube pins? Any suggestions on this would be helpful.

3. My Ceria-tone layout is quite different than this Trinity layout as V2 and V3 tubes are switched in position on the chassis - in the Ceria-tone layout the V3 tube is in the V2 position whereas it is next to the power tubes in the Trinity layout. Why would this be, and what advantage does either hold over the other? It seems odd in the Ceria-tone layout swaps these tubes vs most other amp layouts I have seen. Nic seems like he knows what he is doing yet goes against most layouts I have seen in this regard

4. How important is it to drop wires abruptly from the board to the chassis, and run them right against the chassis to where they are supposed to go? I see some amps laid out with an amazing amount of care, almost like art, and others where wires are pretty hap hazard. My Ceria-tone tends to have most wires reasonably well laid out, but not right against the chassis etc or nearly as carefully bent to the degree that some builds I have seen. They do not always drop abruptly to the chassis, nor do they even correspond exactly in terms of position and wire crossing angles vs the actual layout drawing (some grounds on the ground bus attached to the board are placed in a different order as you run from the input side to the transformer side, some wires do not cross as shown in the layout etc). That said it is still much better than some amps I see

perhaps someone can post examples of good and bad lead dress on an 18 watt and why one is an improvement vs the other??

anyone have any really good threads or sites that go through good lead dress and grounding examples?

Any help is greatly appreciated

Lindsay

The layout drawing is a guide - and a real good one at that. However, don't take it as 100% for the precise routing of the wire, since it has also been drawn to be easy to read, as you suggested.

I was the person who first got Nik into the Marshall 18W world, as he was originally just producing F*nder boards. His first ever 18W board was a Lite II, he did for me, and he used to be a regular contributor on 18watt.com. However, he pretty much dropped out of the 18W community a few years ago, and as a result he didn't get the benefit of certain improvements that came in over time, nor of peer reviews of his later design variants. In this case, the tube order he uses is based on the layout used in the earliest 18W TMB amps, which were themselves based on a modded Classic Tremolo 18W amp. The tube order is therefore not ideal and can sometimes lead to oscillation problems, manifested as hissing or squealing. OTOH the Trinity layout has been purpose-designed as an 18W TMB and is therefore much less prone to stability issues.

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