Avoiding big caps on solid state preamp inputs

[Mr. Moscode]

We don't have a power amp forum. I started a thread here:
https://groupdiy.com/threads/tube-otl-and-zotl-amps.83620/
I was chief engineer at NYAudio Labs. I worked for Harvey until the company collapsed.

 

[Philbo King]

Interesting. Does operating at more conservative voltage (e.g. using a 25v part in place of a 16v part) seem to help?

I used to design aircraft electronics, and the design guideline for caps was to use a voltage rating 2x the voltage the part was exposed to. And 105 deg C parts, always. All lytics had to be RTV'd solidly to the board. The projected design life is 50 years, so they can squeeze extra years out of those 747s/737s...

 

[FIX]

I used to design aircraft electronics, and the design guideline for caps was to use a voltage rating 2x the voltage the part was exposed to. And 105 deg C parts, always. All lytics had to be RTV'd solidly to the board. The projected design life is 50 years, so they can squeeze extra years out of those 747s/737s...

And they have squeezed a "few" extra years. I watched the 747 being built and was really saddened with they stopped using them. Watched a test where they bent the wings up, and the didn't snap off until the tips were 20 feet from each other...

 

[abbey road d enfer]

Interesting. Does operating at more conservative voltage (e.g. using a 25v part in place of a 16v part) seem to help?

Beware that increased nominal voltage often results in increased ESR. In a decently designe circuit, it shouldn't matter, but ...

 

[Matt Syson]

It would be a mistake to RELY on a particular ESR when placed in any circuit because we KNOW it will degrade over time so the circuit as a whole may well malfunction, or go out of design tolerance. If your product only has a 3 or 5 year 'lifespan', (guarantee) that may not be an issue.

 

[Erlend Sæterdal]

Beware that increased nominal voltage often results in increased ESR. In a decently designe circuit, it shouldn't matter, but ...

Beware that increased nominal voltage often results in increased ESR. In a decently designe circuit, it shouldn't matter, but ...

Wow Really? I would never thought this. Absolutely the opposite.

 

[abbey road d enfer]

Wow Really? I would never thought this. Absolutely the opposite.

Interesting.
It seems to be the case for some manufacturers/lines and the contrary for others.

 

[Matt Syson]

Since the 'perfect capacitor' doesn't exist there are many complicated compromises made with formulations, the way the wire lead outs are connected to the plates, the ability to shrug off heat and so on so plenty of scope for 'golden ears' to think of all manner of wild theories based on,,,,,, 'whatever'.
Like the fact that you must use GREEN sleeved wire for ground connections. So while there will be small differences you are also in the realm of 'small differences now, this year but they will be different again next year (as will your ears). ALL of the old classic stuff (often with 'N' as part of the name has degraded over the decades so are not what they were when first made (and nor are we).