Raqs wrote:
Hi all,
Putting this together and could use your clarifications with a couple of things... First and foremost, the size of the PCB from the original post is a little confusing ("After many modifications the PCB was reduced to a 2-1/4" x 4-3/4" and then down to 2" x 4" (50 x 100 mm) with thicker traces. The build is demonstrated on the first version (slightly larger PCB)."). What is the actual size of the PCB in that PDF? If I print it "actual size" (letterhead paper size, though that shouldn't matter) I'm not getting either of the sizes above, but 1.75" by 3.75". Which one is it?
In terms of parts choices, I opted for the IRF610 due to lower capacitances, which I trust should translate in potentially better frequency response (than in the case of the IRF510). Thoughts? Also, thinking of doing this with an 6189 from TD (didn't have any 12AU7s laying around...).
Though have not gotten this up and running, so I don't know if this is necessary, but I may be very interested in exploring a more fully fleshed B+ (I don't mind putting together an actual PS for this). In that case, I wonder what an optimal B+ would be (all things factored in, such as power dissipation on all other parts also).
Does anyone have any direct experience / thoughts on this amp and Pete Millett's Nutube-based amp? I have that other one built and have pretty conflicted feelings on it. I'd be curious of some A/B thoughts.
Looking forward to the project! Thank you all for your input on this.
Radu.
I sorted my PCB issue by downloading the board file and running it in Eagle. For anyone else's reference (possibly needing this at some point in the future), it's 3.75" by 1.75". Built it, adjusted bias (no issues whatsoever), and I'm pretty stunned by the performance. It's one of a few recent headphone amp projects (and trials of factory-built stuff) and this is a damn good one. Not expected. Also, drives my HE400is (difficult load in the low impedance world at 93dB) without losing a beat, very effortlessly. I also expected the low B+ to tax the performance a lot more, I don't really feel it does. Impressed and very happy.