My grounded grid amp project


New member
Username: Jjaudio

Post Number: 4
Registered: Jul-08
Ground Grid Preamp DIY Kit

Grounded Grid tube preamplifier DIY module, simply called as CG preamp, circuit designed by famous tube amp designer: Bruce Rozenblit from Transcendent Sound. Bruce has profound power in design tube amplifier, and good at creating special and unique sound effect. His design is received good comments from US media.

Grounded Grid preamp will not make any artifacts to the sound, and play 100% originally and naturally

For many years, Grounded Grid tube preamp has been tested and verified by many worldwide DIYers. This DIY kit adopts the same amplifying stage which is invented by Bruce Rozenblit. The simplicity of this circuit enables the beauty of circuit symmetricity, and also simplify its power supply circuitry. This kit can be supplied only by using one main transformer (toroid main power transformer T30)

The high voltage supply for the tube preamp is come from the secondary coil (200VAC) of T30. This kit corporates with the RC filter to reduce undesired power supply ripple.

The static current consumption of GG tube preamp (2 channels) consumes approximately 8mA, taking the power consumption of ZENER rectifier part into account, the total current consumption is just about 13mA. The power supply of the filament is come from the secondary coil (12.6VAC ) of T30, with the low voltage dropout of the LT1085CT and relative large surface area of the heat sink, the temperature of the heat sink almost remain the same and it is very stable.

The signal grounding of this small signal preamp is very crital to the overall perfomance, better signal grounding can reduce the noise distortion or addition to the original weak audio signal. In practical experience, either using the method suggested by Bruce Rozenblit: The bypassing the GND of RCA input with a 10ohm (0.5W) or the GND of filtering capacitor via copper strip to the metal chasis, it can greatly reduce the surrounding noise interference. There is no much different of the two methods.

A GND hole for copper strip is designed for this purpose. Just using a copper strip to connect this hole to metal chasis, good shielding and low noise will be resulted.Upload


Platinum Member
Username: Nuck

Post Number: 10633
Registered: Dec-04
Are you building one, Matthew?
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