Shine7.com

12AX7 tube pre-amp




since this tube amp is relatively simple, the wiring will be done on a prototype board. I drew the planned layout on a piece of paper before the actual wiring is done.

 

Prototype board with the pole and tube socket installed.

 

Wiring at the back.

 

Solder the components.

 

Finished.

 

The tube PSU is from a web forum member, it provide the regulated 300V and 12.6V for the amplifier board.

Putting them altogether.

 

Measurement is done at 2V peak to peak output to a 10k load, using my EM-U 1212m PCI sound card and RMAA 6.1:

 

Frequency response -

Total Harmonic Distortion at 1kHz -

The harmonic distortion is exactly as what I wanted : some 2nd harmonic distortion at -70dB with very low 3rd harmonics at -100dB. The RMAA measured THD is 0.033%.

 

There are room for improvement for this simple design : The gain of this preamp is 51 (34dB) ,which is a bit high. The 625 ohm output impedance could be lowered, also higher output current is desired. Therefore I implemented this design with 2 other medium mu tubes to overcome the mentioned disadvantage, see my 12AU7 and 6922 tube preamp.

 

<< Previous Page : Design

 

Page 2 of 2

 

 

 

Privacy Policies | Site Map | Contact Us |