Will this work for 5E3 channels?

[mini612]

I am currently building a 5E3, not from a kit but from sourced parts. I have decided to not do a replica but to do something a little different.  I know that there are 4 channels; Normal 1 and 2, and Bright 1 and 2.  So I have a 4P4T rotary switch laying around and decided to experiment with it to see if I can just use 1 input jack and select any of the channels with this rotary switch.  I did the experiment on my 5f2a build and it worked, well on 2 channels of course, but I am sure the other channels will work as well if on the 5e3!  But my concern is the unwanted hum, as it was humming a little louder than before.

When I did the experiment, I did not secure the 4p4t onto the 5f2 chassis, the 4p4t was outside of the chassis.  I unsoldered the 5f2 inputs and used 1 of the inputs.  I then used alligator clips to connect all the points. I connected the 1m resistor from the 4p4t to ground.  Again, it works on each channel but it was giving a louder hum. 

My questions: is there hum because of the way I wired it up, alligator clips and outside the amp?  or will be this 4p4t give my amp more hum?

BTW, if I were to use this 4p4t, I will be using shielded wires and making sure all the ground wires be at a secure ground.

Thanks

[PRR]

> is there hum because of the way I wired it up, alligator clips and outside the amp?

Seems likely. The input is the most sensitive point in the amplifier. It wants to suck-up all the hum/buzz field in the room. That is why we have closed metal boxes and shielded wire, right?

[mini612]

> is there hum because of the way I wired it up, alligator clips and outside the amp?

Seems likely. The input is the most sensitive point in the amplifier. It wants to suck-up all the hum/buzz field in the room. That is why we have closed metal boxes and shielded wire, right?

Yes!  I’m going to try to use this rotary switch on a 5e3 as it did work on a 5f2.  I will be using shielded wires (4 of them) and if that don’t work, I will shield the whole rotary assembly with something.  I will also be using a on/off/on 3 position switch for channel 1 and channel 2 combine.  I think it’ll work but it’s the unwanted noise I'm concerned about.  Thanks!!!

[mini612]

Update: completed the 5e3 and the 4p4t switch works along with a on/off/on switch (used for combining channel 1 with 2).  I used shielded cables for the 4 channels.  Not much unwanted noise that I can hear at this time.  BUT, it's having other issues. I might have to start a new thread for this.  The issue is Channel 1 volume and MV pot is acting a bit weird.    I used Trainwreck, PPIMV, with a 1m pot.  When MV is at position 1 (starting to open), low volume overdrive/distortion and as I increase the MV past 1/4 to max, it cleans up, in other words, Its not acting like a MV.

[sluckey]

Show us an as-built schematic.

[mini612]

Show us an as-built schematic.

Hi Sluckey,

I am new to tube amp building so I still have to figure out how to put this in a drawing.  I am still trying to figure out the master volume as it's not working like how it should.  I am unsure if the input system is the cause of this.  It's wired exactly like how Rob Robinette described: Trainwreck Type-3 PPIMV.

[shooter]

It's wired exactly like

did you take a chunk of schematic and use it out of context?
what you feed the pot and what the pot feeds are bigger factors than if i wired 3 wires right.


^what Sluckey said
without a schematic, all I see is the forest


fwiw, i did the aluminum tape, caused weird stuff, it's too abstract to be appreciated by many 
Spend some quality time looking at Sluckey's page, the layouts, I got better, anyone can 

[sluckey]

The Trainwreck Type-3 PPIMV is the least loved of all the MV types. I found it nearly useless. I really doubt Rob thought it works great!

[mini612]

The Trainwreck Type-3 PPIMV is the least loved of all the MV types. I found it nearly useless. I really doubt Rob thought it works great!

You are absolutely right!  I just changed it to pre phase inverter.  It works well!  The amp sounds good, to me.  But I don't have a 5E3 to compare it to except youtube sound clips. 

I still have a lot to learn but I'm enjoying it so far.  Thanks everyone!

[pdf64]

… It's wired exactly like how Rob Robinette described: Trainwreck Type-3 PPIMV.

I can’t think how that’s possible?
The Trainwreck Pages shows master volume circuits for Marshalls, connected to an LTP phase splitter.
Whereas a 5E3 has a cathodyne phase splitter.

Things work as part of a system, they interact with, and are affected by, the circuits at their input, output and power supply.

Often it can seem that amps are just a bunch of circuit building blocks strung together, and if they’re lucky beginners can proceed on that basis, but eventually an incompatibility will emerge and things won’t work as expected.