2 Chassis amp

[rvrazvan]

I'm building a 6c33 SET right now. I'm having troubles with the chassis design and i'm considering to make a 2 chassis amp(separate PSU).
Can someone point my in the right direction regarding the design of 2 chassis amps.
What should stay on the PSU chassis(rectifiers, caps, chokes)? How do i ground the chassis.

[pieter t]

Look at Thomas Mayer's blog.
He builds his amps this way; I guess he is willing to help you with this when you have questions.

[MrCurwen]

My principle in chassis design is that no AC (other than signal) in the signal chassis. I think that is a good place to start. Also no electrolytics in the signal chassis.

[pieter t]

Further suggestion:
Morgan Jones: "Building Valve Amplifiers"; can be bought at Ebay for 39.95 USD.
This is great stuff, actually a must when you want to build your own amps, and then some vintage English humor......

[ReinoutdV]

Good morning RVRAZVAN,
i fully support with earlier comments: AC and DC (power supply) separation. All the power supply-components in a single chassis; all the audio-path components in another chassis. Between the 2 chassis a good solid umbillical.

If the distance between that external power supply and the audio-chassis is too big; there is a chance for hummmmmmm because the filaments simply want their supply really close. In that case you can sidestep this problem by placing a capacitor close to the actual component that it must feed. Yes....i know.....then there is no complete seperation of the power supply but you don't want humm anyway. Breadboarding your project will show if you have to do this or not.

Included some pictures of my EL82 amplifier. Monoblock, 2 chassis each amplifier but with a fixed connection (the tubes between the 2 chassis are hollow; the power lines run through these pipes).

Included some pictures of my big amplifier: the TB3/1000. A completely seperate powersupply with umbillicals. But here the distance became too large hence some capacitors near the audio-components.
In the power supply-chassis: power transformers, rectifiers, capacitors, chokes.
In the audio-chassis: audio-components + final capacitors (DC) for certain components.

Good luck with your project !
Regards, Reinout

[56oval]

Hi
The other alternative would be to make a multi layer case and seperate power supply that way .Pwoer supply transformers at the bottom next level chokes ,next level caps and the top section analog stage's .


With my pre I put them in seperate chassis ,power trannys & chokes in one case analog stage's in the other and the umbillical about 1 meter long .

CHeers

[rvrazvan]

WOW. Nice work there( both of you).
My main concern is about the distance between the PSU and the amp. From what i know(might be wrong) the distances must be kept to a minimum between the parts of the psu.
Do i keep any of the filtering caps in the amp chassis or not?
The filaments will be on AC. If i will have the two wires(AC) twisted realy tight an screened i should have no hum issues right?

Also i have a few concerns about grounding an two chassis amp. Hope i won't do anything stupid .

[Original Burnedfingers]

Reinout


This has to be the best workmanship I have ever seen.

[ReinoutdV]

Good afternoon again RVRAZVAN,

the hum-problems do occur at larger distances. Especially when you use AC at the filaments (are you really sure that you think you can get humm-free 12,6V/3,3A or 6,3V/6,6A). Even if you twist your powerlines very tight.

The only logical solution: breadboarding. So first start with a rough lay-out of all working components and test them in the correct set-up. You will find out IF you have a hum-problem; and at what distances.

When you look at the filament requirements of your tube (6C33), please don't be afraid to use really large diameter wiring.......

Breadboarding makes sense. It will reveal sensitive parts of your schematic. For instance at my phonostage (all tubes; pictures included) i found out that it was that sensitive that the distance between the external powersupply (with the transformers and there respective magenetic fields) and the actual phonostage had to be quite large. Simply: i could hear the transformer fiels make a hummmmmmmm in the phonostage. Nothing to do with filaments....just magnetics.
So i had serious distances to cover with my powerlines....then AC is not that smart....this will introduce humm also. I switched to DC. And as the distances were quite large i put the final (DC-)capacitor right at the phonostage where it was neeeded.

The same with my headphone-amplifier: again with external power supply. And again at DC with the last (DC-) capacitor at the amplifier itself.

Pictures included of the phonostage and headphonamp (with pictures of the respective power supplies)

Regards, Reinout

[rvrazvan]

Originally Posted by ReinoutdV

Good afternoon again RVRAZVAN,

the hum-problems do occur at larger distances. Especially when you use AC at the filaments (are you really sure that you think you can get humm-free 12,6V/3,3A or 6,3V/6,6A). Even if you twist your powerlines very tight.

The only logical solution: breadboarding. So first start with a rough lay-out of all working components and test them in the correct set-up. You will find out IF you have a hum-problem; and at what distances.

When you look at the filament requirements of your tube (6C33), please don't be afraid to use really large diameter wiring.......

Breadboarding makes sense. It will reveal sensitive parts of your schematic. For instance at my phonostage (all tubes; pictures included) i found out that it was that sensitive that the distance between the external powersupply (with the transformers and there respective magenetic fields) and the actual phonostage had to be quite large. Simply: i could hear the transformer fiels make a hummmmmmmm in the phonostage. Nothing to do with filaments....just magnetics.
So i had serious distances to cover with my powerlines....then AC is not that smart....this will introduce humm also. I switched to DC. And as the distances were quite large i put the final (DC-)capacitor right at the phonostage where it was neeeded.

The same with my headphone-amplifier: again with external power supply. And again at DC with the last (DC-) capacitor at the amplifier itself.

Pictures included of the phonostage and headphonamp (with pictures of the respective power supplies)

Regards, Reinout

Your work is amazing . I have a role model now ).
I'm playing with the final tube right now on a breadboard but i still need some big parts to buy or make. I will have an alluminium shassis so that will provide some shielding. Where can i see more of your pictures?