I'm on my third build now, and I want to step up the quiet a bit from my first two. I've read here and other places that most of the hiss and buzz happens at the first preamp stage, and that I should try to mitigate that through grounding, routing, and component selection. Grounding and routing I think I have, but can anyone advise what components I should look for on the input side of the preamp? What resistor types should I use and what wattages work best? What other components should I pay attention to that can induce noise into the circuit. I don't mind spending a little extra for the best stuff. Also, any other tidbits to know for this?
I'm at the ordering stage of the board, so now would be a good time for me to learn what's best. Thanks!
Advice for Silent Amp
Moderators: pompeiisneaks, Colossal
Re: Advice for Silent Amp
What amp are you building?
There is much discussion about resistor types if you'll look for it.
Resistor Discussion
How to look for information
There is much discussion about resistor types if you'll look for it.
Resistor Discussion
How to look for information
Glenn
Re: Advice for Silent Amp
You seem to be on a good path, researching this prior to breaking out the wallet.
FWIW component selection, not just value but also composition, is a hugely discussed, and often debated, subject here. Quiet is one thing, but quiet yet great tone is another. I understand you're asking about quiet but that you want great tone is an assumption on my part. Selecting quietest can mean sacrificing tone, so it's a balancing act between the two. I've barely scratched the surface of this myself so don't have much more to offer other than encouraging you to read read read....
FWIW component selection, not just value but also composition, is a hugely discussed, and often debated, subject here. Quiet is one thing, but quiet yet great tone is another. I understand you're asking about quiet but that you want great tone is an assumption on my part. Selecting quietest can mean sacrificing tone, so it's a balancing act between the two. I've barely scratched the surface of this myself so don't have much more to offer other than encouraging you to read read read....
Glenn
Re: Advice for Silent Amp
I don't think there is a best, and if there were none of us would agree on it anyway. Most things tend to be a tradeoff. 5e3 shouldn't be too hissy so I wouldn't overthink it.
Higher wattage film resistors can help with noise, the higher the resistance the more it probably matters, so plates and grid leaks. Vishay PR02 or PR03 series look nice.
You can also cut hiss by cutting high highs, but then you don't have those highs anymore.
Layout, lead dress, and ground scheme are important. Plenty of resources to read about those. The original 5e3 worked great and wasn't noisy, but it can be "improved". Sometimes I use the input gridstopper eyelets for a radial filter cap. Either to move the preamp filter ground point, and/or to add an additional power supply filter stage. Gridstoppers should be closer to the grids anyway.
Some tubes are noisier than others, so it helps to try a few, especially in V1, to find the best option.
To minimize hum, you can install a humdinger pot instead of filament center tap winding or fixed resistors. You can also ground it at the 6v6 cathodes instead of ground for a free 20v of heater elevation.