| Follow the directions below to convert your 5670-powered Manley Variable Mu® to use the 6386 tubes. It's more work to do this than to install our 6BA6 T-Bar mod kits which we charge $250 for (complete and installed with four 6BA6 tubes selected for quad-perfect matching, lo-noise, and lo-microphonics).
If you want us to convert your unit for you, we can. You'll be supplying the 6386 tubes and we will all pray to the Tube gods that they are quiet and internally matched. Maybe buy extras to be sure. Check out our service page for rates and then fill in the RA form to book the service and you can work with Paul on that.
INSTRUCTIONS FOR CONVERTING 5670 TO 6386
1) Replace 3k57 resistors connected to pins 4 & 6 of 5670 socket with 6k8 1W.
2) Replace 1k resistors connected to pins 2 and 8 with 511 ohms.
3) Replace 10k “balance” trimpot with 500 ohm trimpot.
4) Remove 200 ohm resistor between pins 2 and 8.
5) Replace 33k 1W resistor between wiper of “GR cal” trimpot and the junction of the meter with 22K 1W (resistor is located near the rear corner of the pcb next to the GR cal trimpot).
6) Repeat procedure for the other channel; re-calibrate as outlined in the owner’s manual. |