• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Preamp Chassis Layout Advice

Status
Not open for further replies.
Jump to Latest
C

ChrisM91

Member
Joined 2014
#1
I am building a 12B4 CCS preamp to go between my phono preamp and poweramp.

I have now got the designed finalized and have all the parts ordered. With the major parts already here I have got this mock chassis layout for the preamp.


How does this look?
*not all the parts shown are the actual ones I will be using (i.e. volume pot, power switch, etc.)
  1. The RCA jacks will be at the back right corner. 3 pairs of input jacks, 1 pair of output jacks
  2. That input/source selector and volume controls will have shaft extenders to bring the controls to the front panel of the chassis.
  3. There will be two big film caps and resistors at the front of the chassis where the two electrolytic caps are. This is due to the single regulated PSU. The RC filter will decouple each channel.
  4. I have the power switch at the front because it will be an illuminated push button. This does cause a long AC run from the back of the chassis where the IEC is to the front where the power switch is. Not sure if this is a problem? Maybe I should just put a simple power switch at the back?

Any other thoughts or advice?

Thanks!
 
#3
djn said:
Looks good to me. The only suggestion I have is to mount the tubes right under the vents to minimize heat build up. That is a great pre...if you need that much gain.
Click to expand...
Good point

I think for the bottom plate I will have to go this way, just due to space to drill into. I will make sure the top plate has the vents above the tubes though.

Heat does rise after all! 😀
 
#6
Use a tightly twisted pair to bring the "juice" to the power switch. Shield the twisted pair with metal braid that's connected to the chassis. "Dress" the assembly close to the enclosure's wall.

FWIW, I'm not a fan of IEC power connectors. They are just another set of mechanical connections to make trouble.
 
Status
Not open for further replies.
Top Bottom