surfsup wrote:I want to put one on my HO amp to see if it will smooth out the gain a bit. Its cheap, two components, so I'm going to go for it. For the cap:
Here's my question, if I want to put it on a switch, (already have a hole in my chassis) what Amp rating do I need for this? Is a 10A 250V switch acceptable?
So, we are talking about a series RC from SE power output tube plate to ground, right? My 6550 SE amp is running a similar circuit topology to an HO. If I remember, my RC sets a high frequency cut around 7 kHz with a 5K and 0.0047uF.
Given that the highest fundamental frequency on a guitar is 24th fret high e string = 660 Hz, all of the energy in the 5-7kHz range is due to overtones or harmonics. There is not a lot of musical energy at these frequencies and consequently not a lot of current flowing through your conjunctive filter.
Assume you set a filter at 7000 Hz with the above component values. At the corner frequency, the cap impedance equals the series resistor value, so string is 5K + 5K = 10K Ohms. If you measure the RMS voltage swing at the power tube plate, you can calculate how many amps (RMS) are flowing through the filter.
So, for example, I measure 60VAC RMS swing at power tube plate --> current flowing through RC filter = 60/10K < 6mA worst case (because all the music energy in guitar could not possibly be at 7kHz). Remember, the conjunctive filter doesn't pass any bias current. It has current flow only when there is AC signal.
cheers,
rob
