Can DC tube filaments reduce hum?
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jctaudiodesigns
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Can DC tube filaments reduce hum?
Can DC tube filaments reduce hum, and if so by how much?
Last edited by jctaudiodesigns on Fri May 08, 2009 9:21 am, edited 1 time in total.
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paulster
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Re: Can DC tube filaments reduce hum?
Are you on about hum coming from having a guitar plugged in (with single coils, for example), or just the background 50/60Hz hum of the amp itself?
You can make the amp significantly quieter from a background hum perspective with DC heaters (particularly on high gain circuits) but it won't make any difference if the hum you are hearing is coming from the guitar.
That's getting induced into the coils and wiring from external sources, which the DC heaters do not address.
You can make the amp significantly quieter from a background hum perspective with DC heaters (particularly on high gain circuits) but it won't make any difference if the hum you are hearing is coming from the guitar.
That's getting induced into the coils and wiring from external sources, which the DC heaters do not address.
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jctaudiodesigns
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Re: Can DC tube filaments reduce hum?
Hi Paulster, thanks for the reply.paulster wrote:Are you on about hum coming from having a guitar plugged in (with single coils, for example), or just the background 50/60Hz hum of the amp itself?
You can make the amp significantly quieter from a background hum perspective with DC heaters (particularly on high gain circuits) but it won't make any difference if the hum you are hearing is coming from the guitar.
That's getting induced into the coils and wiring from external sources, which the DC heaters do not address.
Actually this has nothing to do with a guitar amp. I am building a bunch of recording gear using tubes and I want to drop the noise floor. What I wanted is to see if anyone has done this and how much of a difference it made.
Also I was wondering how they did it, that is if it required changing the layout of the wires. Can the filaments still be wired the same in parallel (as in pin 4 & 5 together and pin 9 on the opposite end) or do they have to be in series?
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paulster
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Re: Can DC tube filaments reduce hum?
It can certainly make an appreciable difference. You need really clean DC though, or you can end up making it worse as the AC ripple on a poorly filtered DC supply is a 100/120Hz sawtooth wave, which sounds a lot worse than a 50/60Hz sine wave.
Properly filtered/regulated though it'll can definitely reduce the noise floor.
The wiring can be exactly the same. I use 6.3Vdc for all of my preamp tubes in all my amps as it was more convenient for me than generating 12.6Vdc and wiring the filaments in series. You can do whichever suits you best, but bear in mind that the current drawn will be twice the 12.6Vdc figure if you use 6.3Vdc, which could be an issue with your choice of voltage regulator if you decide to use one.
Properly filtered/regulated though it'll can definitely reduce the noise floor.
The wiring can be exactly the same. I use 6.3Vdc for all of my preamp tubes in all my amps as it was more convenient for me than generating 12.6Vdc and wiring the filaments in series. You can do whichever suits you best, but bear in mind that the current drawn will be twice the 12.6Vdc figure if you use 6.3Vdc, which could be an issue with your choice of voltage regulator if you decide to use one.