Sending Dared SL2000a in to repair hum
I've seen several threads lately talking about hum in the Dared SL2000a. Mine has always had a slight 60 hz hum but I convinced myself it was the nature of the beast. I tried lifting grounds, swapping cables, tubes, etc. but nothing changed the hum. It's barely noticeable from the listening position but very obvious a few feet from the speakers.
After reading that some are essentially silent, I contacted Joe at Dared for advice. He suggested I contact Mike at Deltronics in Woodridge, IL. I'll box it up tomorrow or Friday and send it in. Unfortunately, the warranty's up so I'll eat the repair bill. My own dumb fault for not dealing with this sooner. Mike will contact me with a diagnosis before making repairs. I'll post his findings when I hear.
I'm also sending the Auricap input caps I purchased but never installed. Mine has the rectangular input caps flush mounted to the board so I'd have to get access to the back of the board to install. Mike said he can install while he has it apart.
Revelation! Please help interpret.
On a whim, I just hooked up my Yaqin tube buffer between the Dared preamp and NAD amp.
In my old system, the tube buffer still passed the signal through when turned off but speaker output was lower. The gain is 1 when turned on.
I first tried the tube buffer between my Dared and NAD with the tube buffer off. The hum is almost entirely gone! I have to turn the volume knob on the Dared up more to get the same volume but there's no hum. With the tube buffer turned on, the hum comes back.
Do I need an amplifier with a higher input impedance? Someone who understands tube buffers/amplifiers better than I do please help!