However, I am getting more hum than I anticipated.
I bought the low gain version
I am using my thorens turntable, playstation, or ipod into a Marantz pm500 integrated and using the headphone out of the Marantz to get into the st70 which goes to Klipsch Chorus II’s
If I have the unit on and connected to speakers, but with no source, it is dead silent. When I leave the cables into the st70, but short them at the other end, it is still silent.
When I plug the cable into the headphone jack and turn the Marantz on, the slight hum starts.
The hum fades into the background eventually, but at that point it is LOUD. I think I can thank the highly efficient chorus II’s for this
For watching tv or using the playstation, I can only get the gain up to about 8 o'clock for normal listening levels. At 9 o'clock the house is shaking. With the turntable, 9:30 is normal volume. at 8:30 you can hear the turntable, but it is 50/50 hum. at 11 it is almost painful. At about 10 o'clock with the turntable the hum is no longer noticeable, maybe 98/2 or so.
I have recapped most of the Marantz, but maybe I need to look into the headphone section. I have never noticed a hum when using headphones.
I think the problem is that the headphone out is slightly noisy, and that when that is further amplified, the hum becomes noticeable. Sound right?
If I bought an earlier Marantz integrated with a preamp out, could I use that and would that be quieter? I could also open up the pm500 and find the preamp/power amp function and run a line to the rca's on the back...
I cant really afford a tube pre, but maybe in the future I will get a dynaco pas3 and modify it with the other vta boards for it. This will be awhile in the future though…
I know I can adjust the feedback resistors on the vta board, but it seems to me like the problem isn’t the vta board.
Any ideas for solutions to this?