Grounding scheme questions

[pablogt]

Hi all. This is my first post in this forum, although I've been reading for the last couple of months or so. I decided to build my first Trainwreckish amp and I'll start with a Rocket. I already got most of the pieces I need from rjguitars.net, including a gorgeous set of cherry cabinet, chassis and custom faceplate (thanks again, rj!).

The changes I want to do to the standard Rocket are putting the filter caps on a board and a few non-essential tweaks like parallel input or so, like most of the rocetish builds I've seen on this forum

I have a question regarding grounding of Trainwrecks in general. I understand that many of the participants in the forum realize that the distributed grounding used is against every rule in the hum-hunting book. Grounding the PT's away from the filter caps look specially anathema to me. I started thinking of sending every filter's ground to the "proper" place to build a multi-star grounding scheme the way that Kevin O'Connor and Merlin Blencowe recommend in their books (one local star for each filter or smoothing cap).

But then, there are a few things that prevent me from doing it:

1.- Those long ground leads might worsen hum instead of improving it
2.- "Rockit" builders seem to be getting further away from star grounding with every build. Have you noticed changes in hum?
3.- I'm convinced that Ken Fisher knew about these ground schemes and did not use them for some reason.

So, my question is: Can someone point me to any literature, maybe a Ken Fisher article, that could help me understand why he used this kind of "distributed grounding"? I already read all the Trainwreck pages as published in Gerald Weber's books and don't recall a word about grounding.

Thanks everyone for sharing so much info. I'll do a complete post once my Rocket build is done, although I doubt I can add much to what is already here!

Pablo

[rooster]

Pablo - Welcome. Yur post is being ignored because it's a blugeoned topic. It seems a simple question to you but typically would require a book to answer.

Read the build guides and pay close attention to the notes. That will help. Good luck.

[pablogt]

Thanks for your answer. I looked for a related thread and did not find a single one. I'll read the Express build guide.

P.

[M Fowler]

Since your talking about not building a traditional TW clone I think your smart to put in a cap board or two can caps.

Pasting cap stacks into an amp isn't right, the cap board is solid.

Nothing wrong with rethinking the grounding scheme at all.

Your going to end up with a sweet Rocket in the end building smart.

Mark

[overtone]

Hi Pablo,
there was a thread a while back which presents very many different placements of the caps in a TW type build. Generally, you'll see two different approaches:
1. mount the caps on their own remote board
2. actually mount the caps right next to the stages they serve, which forces a layout re-design.
https://tubeamparchive.com/viewtopic.ph ... ap&start=0

Re. long leads increasing hum:
To my mind you need to pay close attention to the route of the current between the CT and the -ve pole of the first reservoir cap. That routing could radiate into places you would not enjoy. With respect to trying your own ideas I think you will find the Rocket circuit very forgiving. Enjoy the build and using the amp,
best, tony

[pablogt]

Hi all.
Thanks all for your input. Tony, the link was most useful. What I will probably do is bring the preamp filter grounds to the corresponding cathodes, but without physically putting the caps there (I already got these nice perf boards made by rj). These will be grounded at the input jack. The reservoir and screen caps will go to another star which will be connected to the other stars or will go direct to ground (I'll try both ways). The PT center tap will go directly to the first cap's cathode turret. I'll probably use non-isolated output jack sockets since, without NFB, the currents should be negligible.

Thanks again,
Pablo