Sunday, May 29, 2011
ZABS Suitcase PP/SE
Why hide your amp behind wood and tolex? The ZABS Suitcase has nothing to hide! My main goal for this project was to make an amp with a lot of sound possibilities. From clean to mean and suitable for different styles of music. Low volume and a unusual design and housing. Top cover is made of plexi glass. With a marker you can draw your own design or make notes for example about the setting of the amp for a song. The Suitcase offers two channels and two different power amps. You can choose between a single ended 6V6 power amp in class A (2 Watt) or a push pull 6021 powerstage class AB (700 mW). The preamp uses 6112 submini triode tubes. Channel I has 2 gain stages. Channel II consists of 3 stages and has the option to swich in a bit or a lot more gain. Both channels have there own gain control.
After the preamp comes the cathode follower, treble, mid, bass tone stack and master volume. When the SE 6V6 power amp is used the signal goes from the master volume after the tone stack straight into the power tube. No overall negative feedback (nfb) is used in the SE power amp.
The PP 6021 amp has another gain stage after the master volume followed by a cathodyne phase inverter; a submini 6021 is used for both functions. Gain is tweaked with split plate resistors to avoid the small power tube to be overdriven too early and too much. The PP amp has features as Presence and Resonance in the nfb. Bias can be switched between catode and fixed bias for a more tight sound. B+ rail for the amp is around 190V.
It was great to experiment with the small submini tubes and combine them with a 6V6.
Dimensions (inches): 17 x 9 x 3
Sound samples: 1. SE clean channel 2. SE OD channel 3. SE OD channel xtra gain 4. PP amp
# posted by Jaap Knoppert @ 2:57 PM 
Comments:
Post a Comment
<< Home
<< Home
