Volume, balance, oh my…

As part of our new affordable line of electronics, Stellar, we're building what's known as a "pre-DAC" though I am not big on that term. A pre-DAC is a preamp and DAC combo. Analog preamp, digital DAC, one box. The term I prefer is Control DAC and that's what the new Stellar piece is called. The biggest challenge in building such a device is not the DAC. Sure, that takes a great deal of skill and technology of which we will certainly lavish tons upon it. But the real challenge in building a sonically wonderful analog/digital instrument turns out to be the preamp. It took Bascom King the better part of 50 years to come up with a preamp as good as the BHK Signature. Preamps and power amplifiers are perhaps among the most challenging products to design when expectations are high (and when aren't they?). Looking deeper into specifics of preamp design challenges we find the volume control is number one. And worthy of discussion. I thought perhaps we'd spend a few days talking about preamps and volume controls as the subject moves me to write about it. Let's start at the beginning (novel idea, that). A preamplifier consists of three essential elements:

• Input selector
• Volume/balance control
• Gain stage

All three are vital elements in successful designs. Failure to pay attention to any of the three gives less than grand performance when sonics matter—and in our world, sonics always matter. A lot. Tomorrow I will detail some interesting notions and challenges with the input selector section, then we'll move on to the meat of the discussion, the volume control.