tubologic
Well-known member
- Joined
- Mar 29, 2009
- Messages
- 72
I just found this circuit in the Oct.1954 issue of RADIO-ELECTRONICS magazine and thought it might be interesting to some DIYer's and experimenters. It's a simple vari-** type tube compressor using only 4 cheap common radio tubes and a voltage regulator.
Performance is quite good for such a simple circuit, the main limitation factor is that being a single-stage circuit it has not much gain. There's provision for input tubes balancing and treshold level adjustments (the 25K pot across the OD3 regulator). The dual recovery time constant can be easily modified by altering the values of R1/C1 and R2/C2. A 12AT7 side chain driver amp is used to give a faster attack time. Recommended transformers were UTC A-12 for the input and A-27 for output but other xfmr's may fit.
Simple,cheap, easy to build, common parts and decent performance: can we ask for more ? Maybe a good basis for your next "poor man's" tube compressor ? Full description and construction details can be found in the above magazine.
Performance is quite good for such a simple circuit, the main limitation factor is that being a single-stage circuit it has not much gain. There's provision for input tubes balancing and treshold level adjustments (the 25K pot across the OD3 regulator). The dual recovery time constant can be easily modified by altering the values of R1/C1 and R2/C2. A 12AT7 side chain driver amp is used to give a faster attack time. Recommended transformers were UTC A-12 for the input and A-27 for output but other xfmr's may fit.
Simple,cheap, easy to build, common parts and decent performance: can we ask for more ? Maybe a good basis for your next "poor man's" tube compressor ? Full description and construction details can be found in the above magazine.