Post by alerich on Mar 1, 2013 11:37:11 GMT -5
I've been working on my Splawn Mig60. Removed the low input and its gain control. I never used them and the low gain control was on a push-pull pot. When you pulled the pot it disconnected the low input and added the pot to the hi gain pot in the same manner that the Splawn solo boost operates. Neat idea on paper but it was too over the top and noisy.
Since I now had an available control position in the faceplate I decided to add the solo boost function found on the Quick Rod to my Mig60. First, I repositioned the controls. Scott had placed the gain control for the hi input way over by the pilot light - all the way diagonally across the amp. Not a good idea to string wires (even shielded wires) all the way across an amp like that. I moved it back to its rightful spot next to the input jack now requiring wires of only a few inches in length. I shifted the remaining controls one position to the left and used the now vacant position between the gain and master for the solo boost.
The solo boost operates essentially like the Quick Rod. I used a 500K audio pot. I activate it with a 5VDC relay that is powered off of the Mig60's DC heater supply. It's wired to the former low input jack and a simple latching foot pedal activates it. That is a neat feature. Wish I had sussed that one out in the 80s. Trés useful.
I have dissected Scott's mods component by component. Nothing terribly elaborate on this amp like some of the others I have seen. No added tube stages or channel switching or anything like that. Just really adding more gain and re-voicing a little. Cathode follower converted to a gain stage. Pretty standard JCM800 mod fare. Have been tweaking it a bit to suit my tastes and cleaning up some of the rushed looking solder joints. Sounding better every day.
I decided to re-cap the beast. Not a trivial matter since the original Russian cap cans are basically unobtanium. I had to retro fit current production axial e-caps in the power supply but it came out well and sounds stellar.
Love this amp.
Since I now had an available control position in the faceplate I decided to add the solo boost function found on the Quick Rod to my Mig60. First, I repositioned the controls. Scott had placed the gain control for the hi input way over by the pilot light - all the way diagonally across the amp. Not a good idea to string wires (even shielded wires) all the way across an amp like that. I moved it back to its rightful spot next to the input jack now requiring wires of only a few inches in length. I shifted the remaining controls one position to the left and used the now vacant position between the gain and master for the solo boost.
The solo boost operates essentially like the Quick Rod. I used a 500K audio pot. I activate it with a 5VDC relay that is powered off of the Mig60's DC heater supply. It's wired to the former low input jack and a simple latching foot pedal activates it. That is a neat feature. Wish I had sussed that one out in the 80s. Trés useful.
I have dissected Scott's mods component by component. Nothing terribly elaborate on this amp like some of the others I have seen. No added tube stages or channel switching or anything like that. Just really adding more gain and re-voicing a little. Cathode follower converted to a gain stage. Pretty standard JCM800 mod fare. Have been tweaking it a bit to suit my tastes and cleaning up some of the rushed looking solder joints. Sounding better every day.
I decided to re-cap the beast. Not a trivial matter since the original Russian cap cans are basically unobtanium. I had to retro fit current production axial e-caps in the power supply but it came out well and sounds stellar.
Love this amp.