Thanks for your patience! I’ve spent the past few days putting the final touches on the Audio Note Kit 1 300B SET amp. Those of you who have stuck with me through this adventure are about to see the fruits of all of our labor.
First, here’s a shot of all the wiring, finally completed. As I mentioned in my last post, I’ll be doing some largely aesthetic cleaning up of the wiring once I’m sure that everything is working properly.
In the previous post, we confirmed with our multimeter that we had 5 DC Volts running across the fat pins (the filament pins) of the 300 B tubes. A lot of things have to be working properly for these values to be correct, so this is good news!
Now, we’ll add all the other tubes except for the rectifier tube and measure a bunch of other DC voltages.
Here are photos of the sweet looking 300B boxes:
And here’s a shot of the amp with these and the three frontmost tubes in place:
The assembly manual provides the details of the crucial voltage values and where to measure them. (For Newbies like myself, you place your red multimeter probe at the point indicated in the diagram, and the black probe goes to one of several ground points.) Taking these measurements requires inserting the the tubes in their sockets and then very carefully turning the amp upside down so that you still have access to the innards of the amp. I propped the amp up with stacks of strategically placed books to make sure that the tops of the tubes, some of which are taller than that big output transformers, were not hitting the table. Slow and careful is the rule in manipulating a nearly 50 pound amp in this way!
Now we flip the amp over (carefully!) as noted above, say a little prayer, and engage the power switch. One thing we want to see at this step is a glow in the tubes we’ve inserted. And, lo and behold…
With all our measurements looking good, we’re really ready to try to get some music out of this puppy. The manual recommends testing the amp with a pair of cheap speakers first, but Brian Smith of Audio Note Kits reassured me that with my voltage measurements looking good, I could just hook them up to my real speakers (Reference 3A De Capo BE’s) and let ‘er rip.
Here’s one shot of the Kit 1 in its new home, with its companion SOTA Sapphire turntable to the left.
And here’s a “glamour shot” of the amp from another angle with a good view of all that luscious tube-osity. Note that Brian was nice enough to send me a 274B rectifier tube (the one between the two transformers on the left) instead of the standard 5U4G rectifier tube. It’s supposed to be a small upgrade over the standard tube.
My favorite story so far about this amp involves letting my music loving but non-audiophile wife and daughter see the completed amp for the first time. “You built that?” they marveled. “It’s beautiful!” Yes, major WAF here.
Most important, I am happy to report that our Audio Note Kit 1 is making music! I will keep you waiting a little while for detailed reflections on the sound of the amp while it is burning in. Expect a future report on the sonic qualities of this amp.
Stay tuned for more and thanks for reading…