Just another /\|OOB to Tubes....Need Schem Help

[benjamins100]

Hey everybody, I need some help. I am really into mod's and I am working on a periphial that uses solid state amplification and I wanted to Incorporate a 12ax7 tube into it. There is only one problem, I have no Idea how to put together a basic tube circuit..... I am such a Noob to this I need to have it explained to me like I am a 5 year old.... It's just really confusing for me, All this stuff about having a Negative Bias, Etc

What I do know is that, you have to apply voltage to the tubes "Heatre" nominally 12.5 Volts, up to 16v A-C......Ok, so after you hook up your wires to the "Heatre" where is the Mic Signal go through? Do you Tie it into the A/c Voltage?? LOl, Or To the Grid?? Idk.... How do you get the Negative Bias?? Etc....

I have a Presonus Studio Channel that costed Me $350.00, When I opened it up, I was amayzed how little components were inside...However Presonsus says this does not have any solid state I'cs inside of it... But when I looked inside, on the Mic input and Output there are 2 I'cs. I don't think that these are Instrument Amps, they are probably for phantom power or eq or compressor mabee but I am not sure... but I am not sure because I have not looked up part numbers yet.... Anyhow, This particular Pre has a 16v wall transformer.. Thats how it powers on.

I am trying to mimic the design of this tube pre, since it is so simple.... Even if I had to use a solid state I'c to get some results that would be fine, I know thats sort of cheating, but the device I have uses all solid state and does not sound to well, I wanted to remove the I'c from this device aka "Bypass" their IC and Install A New I'c that has wide bandwidth, Low distortion and then run it through a tube if I had to, I rather not use solid state, but if I have to thats fine...

All I want to do is make my Tube heat up and run some vocals through it, Thats it, nothing special, Tube drive would be nice but thats it. I don't need 48V Phantom Power, My Periphial has it, so does my external Pre.. Just wanna run the audio throught the Tube and Directly into my Analog To Ditigal Converter. (Logic Device, Not Phy)

I allready have a 12ax7 tube, a 16v ac wall transformer, I have a bunch of 220uf 100v and 50v 4700uf Caps..... What else to I need Resistors? Transistors?

[rotaspec]

Here's a good read for you to start:
Valve Wizard - How to design valve guitar amplifiers

Try the link on the left menu for Triode Gain Stage.
You're going to need more than a 16v wall wart for a 12ax7 though.

[jmilch]

Originally Posted by rotaspec

Here's a good read for you to start:
Valve Wizard - How to design valve guitar amplifiers

Try the link on the left menu for Triode Gain Stage.
You're going to need more than a 16v wall wart for a 12ax7 though.

Excellent link, thats helping me out a bit too.

[kavermei]

Originally Posted by benjamins100

What I do know is that, you have to apply voltage to the tubes "Heatre" nominally 12.5 Volts, up to 16v A-C......

I wouldn't exceed 13 volts if I were you, it will drastically reduce the life span of your tube.

You can still use the 16V wall wart, if you place a series resistor of 27 ohms in series with the heater of the 12AX7 (pins 4 and 5). The resistor should have a 1 or 2 watt rating.

Pin 9, the center tap of the heater, can be connected to signal ground for minimal hum.

Pin numbers are clockwise looking from below the socket. If you get a socket which has the numbers stamped on them, you can't go wrong.

[kavermei]

Originally Posted by rotaspec

You're going to need more than a 16v wall wart for a 12ax7 though.

I think he was talking about the heater power...

[rotaspec]

Originally Posted by kavermei

I think he was talking about the heater power...

Er, no, I don't think he knows that he also needs a plate supply.

[Eli Duttman]

Originally Posted by benjamins100

Hey everybody, I need some help. I am really into mod's and I am working on a periphial that uses solid state amplification and I wanted to Incorporate a 12ax7 tube into it. There is only one problem, I have no Idea how to put together a basic tube circuit..... I am such a Noob to this I need to have it explained to me like I am a 5 year old.... It's just really confusing for me, All this stuff about having a Negative Bias, Etc

What I do know is that, you have to apply voltage to the tubes "Heatre" nominally 12.5 Volts, up to 16v A-C......Ok, so after you hook up your wires to the "Heatre" where is the Mic Signal go through? Do you Tie it into the A/c Voltage?? LOl, Or To the Grid?? Idk.... How do you get the Negative Bias?? Etc....

I have a Presonus Studio Channel that costed Me $350.00, When I opened it up, I was amayzed how little components were inside...However Presonsus says this does not have any solid state I'cs inside of it... But when I looked inside, on the Mic input and Output there are 2 I'cs. I don't think that these are Instrument Amps, they are probably for phantom power or eq or compressor mabee but I am not sure... but I am not sure because I have not looked up part numbers yet.... Anyhow, This particular Pre has a 16v wall transformer.. Thats how it powers on.

I am trying to mimic the design of this tube pre, since it is so simple.... Even if I had to use a solid state I'c to get some results that would be fine, I know thats sort of cheating, but the device I have uses all solid state and does not sound to well, I wanted to remove the I'c from this device aka "Bypass" their IC and Install A New I'c that has wide bandwidth, Low distortion and then run it through a tube if I had to, I rather not use solid state, but if I have to thats fine...

All I want to do is make my Tube heat up and run some vocals through it, Thats it, nothing special, Tube drive would be nice but thats it. I don't need 48V Phantom Power, My Periphial has it, so does my external Pre.. Just wanna run the audio throught the Tube and Directly into my Analog To Ditigal Converter. (Logic Device, Not Phy)

I allready have a 12ax7 tube, a 16v ac wall transformer, I have a bunch of 220uf 100v and 50v 4700uf Caps..... What else to I need Resistors? Transistors?

Tubes are high voltage, low current, high impedance devices. If you are familiar with "N" channel/depletion mode FETs, then you have an idea about how tubes are set up.

If 100% of the power the Parnasus unit uses comes from the "wall wart", there must be a voltage multiplier on the PCB to generate B+. Look around for something resembling either of the 2 circuit fragments in the graphic ("ripped" from Voltage Multiplier, Inc.) I've uploaded.

The 12AX7 is a high gain twin triode with absolutely wretched load driving capability. You need to provide the "crowd" here with info. about the gain structure needed in your application and the nature of the load to be driven. There's a high probability the 12AX7 is not suited to the task at hand. That should not be surprising, as scads and scads of different types, with greatly varying characteristics, have been introduced in both tubes and SS.