Can voltage be mixed with coupling caps?


I’m updating coupling capacitors in the line and phono sections of my preamp. Because of cramped space, I need to divide each 1.0 MFD 400 VDC position into three caps of .33 MFD. But two will be at 600VDC (on top of the board), and one at 400 VDC (mounted under the board). Is there any compromise of performance in mixing the voltages of these high end Teflon caps in each summed coupling position?

Also, …how lead sensitive are coupling capacitors in a preamp. Again, because of larger caps and limited space, I need to make the leads asymmetrical (one will be twice as long as the other). The original mounting hole’s spread is much longer than I will need for the new caps, but the caps are fat and need to be moved away from the heat of the tubes. Generally speaking, do leads contribute to capacitor performance? Any tweaky opinions on this?
pandro
Assuming that a 400V cap have the sufficient voltage rating needed you should be fine. Having mixed leads length is a non issue, however you should insulate the leads between the capacitor body and the PCB for an example by sliding a teflon sleeve over them.

Best of Luck

Peter

PS theres some other capacitor options here

True Copper Cap

Jupiter Copper/Paper Capacitor
Just be aware that multiple caps can cause smearing of the signal due to differences in the parts. Usually its best just to give it your best shot with a single cap than to make up a value with paralleled parts.
I have good ears, and can usually tell when something is audibly “off.” I’m not sure I have ever experienced “smearing” – so, is it that the detail and air is lost? Is this more about definition than any other problem one can hear?

The dilemma in updating vintage gear is finding enough space to install upscale capacitors which tend to be much larger than a board can handle. In most cases there is little option other than ganging caps in parallel. I did this recently in one preamp, and the results were spectacular. I keep listening to find anomalies, but the sound is so good – one never knows when to stop, or if the right path has been taken. Having tweaky OCD, I keep trying top the last effort, as most audio mice will want to do. Can you be specific as to what the “smearing” effect will sound like?
Pandro, Atmasphere is right, never ever mix coupling caps, and they will smear the sound as the sound travels through them at different speeds, and they will especially smear at each ones time constant points if they are different values or voltages. Always use a single HQ cap coupling.

Saying that the best cap is no cap at all if the circuit allows, and the DC offset can be nulled out.

However it is OK to mix and parallel up de-coupling, or power supply caps, and it is encouraged, as it lowers the total power supply ESR (series resistance), which "stiffens" the supply and gives a tighter controled sound to the bass.

Cheers George
George and I often disagree but on these points we are 100%.