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Hi there,

My Triwatt build is coming along slow and steady - so far, no major catastrophes. It's been almost 30 years since I've dove into a project with this many parts so lot's of re-learning going on. Been using both the schematic/layout diagrams in the supplied manual + the Zaphod Build Pics thread for direction but have noticed some deviations in the Zaphod Build Pics thread compared with the layout diagram.

Zaphod's build pics appear to show that polarity of the heater wiring to the power tubes isn't maintained as it is for the preamp tubes but the layout diagram does indicate polarity is maintained (red wire to pin 2 of both power tubes, brown wire to pin 7 of each). Confirming my suspicions, the polarity of the heater wiring isn't necessary for the power tubes?

Also, the wiring of the power transformer to the standby switch/fuse/mains appears to be backwards to the layout diagram - I'm guessing the following either wiring is fine; the standby switch will still work the same regardless of which one I follow?

Lastly, the wiring of the bias pot seems pretty different in Zaphod's build pics compared to the layout diagram.

Probably being a little too over-analytical, but I'm a little curious.

Sounds like you're having some questions similar to what I went through. I used the Zaphod build pics a lot because they were extremely helpful, but in cases where they weren't clear I simply went with the layout. He also provided some helpful info replying to my posts. If you check out some of my posts you'll see what I mean.

Thanks Roadstar. Your build looks fantastic!, by the way.

Follow the layout

Maintain polarity on the power tubes. The polarity on them is what matters. 12AX7s are hum cancelling, the power tubes are not.

Power switch wiring follow the layout, might be different because he added a relay PSU board. Fuses and switches don't have polarity so they will work either way. That said follow the layout to wire the fuse the "safe" way.

Zaphod grounded the bias supply differently than the layout.

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Thatnks for the compliment "Fret'. It's a pretty involved amp to build so I took a lot of time to build it. It wasn't like I needed the amp for a gig so I could afford to be patient. Good luck with yours. I'd be interested in seeing some progress photos.

As far as I know I did maintain heater polarity on the power tubes. It *is* important. But I am partially colour blind, so sometimes mistakes can happen.... And the all the Triwatts I've built have been very quiet, so I think I did actually get it right, despite what the photo may appear to show.


Stephen and I developed the official layout between us, but after that I came up with a few little extra tweaks to improve the layout in the builds I did. I am kind of anal like that...

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Great tones come in small glass jars!

If you don't mind sharing, etc., I am about to embark on mine.

I didn't document them anywhere, but you should be able to see them if you study my build pictures. For example, the way the ground is wired in the power section. Also how the long signal runs are done along the side of the board, with shielded cable used for some.

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Great tones come in small glass jars!

The picture is here: http://www.trinityamps.com/ForumGallery ... _board.jpg

There have been a lot of Triwatts built, and the layout has been very reliable. But I do intend to take another look at it and compare.

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Stephen
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