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So it's been a few years since I've even looked here but I remember there being a lot of useful information so I'm turning to this forum once again.
I really only semi know what I'm doing here btw, so don't be cruel
So here's my issue: I'm trying to make a tube preamp. I saw this thing --> The Persuader | MOD Kits DIY and decided i didn't wanna spend money on it so I thought I'd make my own. In that case I decided to start off simple and use half of the 12AX7 as a single triode preamp.
The triode : Electron Tubes
I have it set up exactly as that schematic shows about half way down the page, with R=5kohm, and no cathode resistor. I determined 5k because I thought maybe it'd be a good idea to reduce current flow a little so i figured I'd only have something like 7 volts on the plate, I forgot what numbers I went for but I used the graphs from the pdf to determine that. I'm using a 9V battery like the persuader does, except I'm using separate 9V's for the bias and for the heater. I have 6.3 volts across the heater as specified in 12AX7 datasheet pdf files. The input jack connected directly to the grid, and the output jack connected to the plate, before the plate resistor like in that schematic.
I finish putting it all together, and I see the heater start to glow so I know that's working okay. I plugged my guitar into it, and then i plugged it into my twin reverb. All it did was hum. So in a state of panic i took out the 5k and redid some connections and then no noise at all came out. I think I just misconnected something at that point, but my question is, where did I go wrong with my initial setup?
I made sure like 10 times that the cathode/grid/plate I used were all part of the same triode unit within the 12AX7.
In the persuader they use what i think is a transistor before the tube stage:
http://www.guitarkitbuilder.com/img/...ersuader18.jpg
I don't have anything like that on hand and I don't really wanna use it either. Is 9V just too little bias for a single triode? Does the signal need to be amplified through the second unit to achieve enough gain to make my guitar signal come out the other end? I also realized later on that I had no resistance before the grid, or no "grid stopper" resistors i think I've seen them called before? Maybe I burnt out the grid with my guitar before I even had a chance to hear it? Or maybe I was just dumb and had my connections all wrong.
Thanks for any help anyone has to offer.
I really only semi know what I'm doing here btw, so don't be cruel
So here's my issue: I'm trying to make a tube preamp. I saw this thing --> The Persuader | MOD Kits DIY and decided i didn't wanna spend money on it so I thought I'd make my own. In that case I decided to start off simple and use half of the 12AX7 as a single triode preamp.
The triode : Electron Tubes
I have it set up exactly as that schematic shows about half way down the page, with R=5kohm, and no cathode resistor. I determined 5k because I thought maybe it'd be a good idea to reduce current flow a little so i figured I'd only have something like 7 volts on the plate, I forgot what numbers I went for but I used the graphs from the pdf to determine that. I'm using a 9V battery like the persuader does, except I'm using separate 9V's for the bias and for the heater. I have 6.3 volts across the heater as specified in 12AX7 datasheet pdf files. The input jack connected directly to the grid, and the output jack connected to the plate, before the plate resistor like in that schematic.
I finish putting it all together, and I see the heater start to glow so I know that's working okay. I plugged my guitar into it, and then i plugged it into my twin reverb. All it did was hum. So in a state of panic i took out the 5k and redid some connections and then no noise at all came out. I think I just misconnected something at that point, but my question is, where did I go wrong with my initial setup?
I made sure like 10 times that the cathode/grid/plate I used were all part of the same triode unit within the 12AX7.
In the persuader they use what i think is a transistor before the tube stage:
http://www.guitarkitbuilder.com/img/...ersuader18.jpg
I don't have anything like that on hand and I don't really wanna use it either. Is 9V just too little bias for a single triode? Does the signal need to be amplified through the second unit to achieve enough gain to make my guitar signal come out the other end? I also realized later on that I had no resistance before the grid, or no "grid stopper" resistors i think I've seen them called before? Maybe I burnt out the grid with my guitar before I even had a chance to hear it? Or maybe I was just dumb and had my connections all wrong.
Thanks for any help anyone has to offer.
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