Dynaco Mark VI feedback values

[mr2racer]

Hello All,

I have a pair of Dynaco Mark VI power amps. I modified them to use a 12AU7 long tail phase splitter and KT 88 outputs. After tuning the feedback on my 8b clone I realize that the Mark VI's might benefit from a little feedback.

My question is where is a good place to start so that I don't damage anything? The Original PC 44 Dynaco board included feedback taken from the 16 ohm output. It was connected between two series cathode resistors of the 7199. (What is curious is that the 8b used almost identical cathode resistors, 1.2k and 180 ohm for the current 12AU7 LTP, and 1.2k and 178 ohm for the Marantz.)

The original Dynaco used 3k/390uuf paralleled connecting the 16ohm output to a point between the cathode resistors of the preamp tube. Also a 150uuf cap connected from the same point to the one of the ultralinear connections on the OPT via the grid connections of its output tubes.

I know I have to tune it. But would these values be a good place to start?

Kevin

 

[mr2racer]

Never mind, I'm just going to start with the original caps and a 5k pot mounted on top of the chassis. That should work to get the value then just replace the pot with the correct resistor.