12AX7 vacuum tube pre-amp?

[AnimusDivinus]

for my record player, ive come to a decision on exactly how this thing will be built, and i will modify it as i go to get better and better each time, but one thing i will need is a pre-amp...

id like to keep this all analog and use a simple 12ax7 vacuum tube for the pre-amp, it can be either two 1-channel pre-amps on a single perfboard, or a stereo preamp... but im looking for simplicity, with adjustable volume control of course...

does anyone have a simple schematic that would use the vacuum tube, simple component parts, and be able to be assembled on a perf board?... not interested in integrated circuits for this one, trying to keep it a little old fashioned if i can

[DF96]

Perf board is not commonly used with valves. Matching a rectangular array of holes with a circular array of valve socket pins can be tricky. Three constructions usually used with valves: point-to-point, tag board plus ptp, PCB.

For circuits use Search on here or Google. There is a simple RCA phono preamp using a 12AX7. It has flaws but will get you started. I assume you are familiar with safety using high voltages, and mains PSU etc.? If not, start with a kit.

[AnimusDivinus]

perfboard, tag board.. im just not too interested in the integrated circuits for this... id like to preserve a classic look... ive found some schematics that look go though, ill look into them further

[Loren42]

Originally Posted by AnimusDivinus

perfboard, tag board.. im just not too interested in the integrated circuits for this... id like to preserve a classic look... ive found some schematics that look go though, ill look into them further

The classic look, at least from the inside, is point-to-point wiring.

[AnimusDivinus]

perfboard looks classic too, but a bit more organized

[SY]

Originally Posted by DF96

Perf board is not commonly used with valves.

Except around here (see His Master's Noise article for an example), where it's standard practice. Punch a hole in the board to mount a standard chassis-type tube socket. The other components mount as usual.

[DF96]

OK, I live and learn!

[AnimusDivinus]

SY, exactly my idea, ive seen many homemade guitar amps made the same way as well which is where i got the idea..

also, i should note that the 12AX7 is optional, it just seems to be the most common with the most support and easiest to find, if theres a better preamp tube for audio quality in a diy phonograph, id be willing to use it

[Alain Poitras]

Originally Posted by AnimusDivinus

for my record player, ive come to a decision on exactly how this thing will be built, and i will modify it as i go to get better and better each time, but one thing i will need is a pre-amp...

id like to keep this all analog and use a simple 12ax7 vacuum tube for the pre-amp, it can be either two 1-channel pre-amps on a single perfboard, or a stereo preamp... but im looking for simplicity, with adjustable volume control of course...

does anyone have a simple schematic that would use the vacuum tube, simple component parts, and be able to be assembled on a perf board?... not interested in integrated circuits for this one, trying to keep it a little old fashioned if i can

This one seem to be very good :



Thanks to the cathode follower last stage, with is low 10K load impedance, you can use any volume control, 50K is the best ...

It use three 12AX7 for two channels, just add a simple supply over 250VDC and it will be perfect, you will just have to adjust the R12 voltage dropping resistor, the same zeners and filter capacitors can be use for both channels. It is an easy to build project on a good steel or aluminium frame, there is no need for a PCB for all the circuit, just a little "general use" for the passive parts beside the tubes on sockets installed on top of the frame with the power transformer ...

Cheers,

Alain.

[AnimusDivinus]

is it possibly to run two channels through a single 12ax7 tube for an even simpler setup?...

the alain posted looks really simple to build, and looks like it would be great for really hi-fi stuff, has anyone used it?