Well I made progress, she sings! Here is a crappy cell phone pic. Now I need to put a skirt on this lady!
My lady bought the plate for me for Valentines day! What a gal!.
I'm another proud builder and owner of the Millett "Engineer's Amplifier" (DCPP).
I stuck pretty well to the BOM and details on Pete's website, only deviating on the chassis style. I also used 6JM6 (plate cap) Compactrons, mostly because I had lots of them. Pete made a good call spec'ing the Edcor iron; the value is excellent. The quality of the Millett PCB is very high and worth every cent Pete asks for it. It was an easy project given the well-designed layout of the board, and the great documentation available on petemillett.com.
This amplifier has the potential to embarrass factory-built gear costing much more. The sound is very dynamic, yet totally easy to listen to for long sessions. It appears to be making more than the 17wpc Pete claims. It is also dead quiet; a pleasant surprise compared to other tube amp projects I have built.
I have it currently driving a pair of Vandersteen 2Ci's. These speakers don't really like less than 40wpc, but are making great music in my average-sized room. The bass is astonishingly good with plenty of detail in the mid-range.
Considering the money spent, this design is a "giant killer". Build it and you won't be disappointed! Congratulations to Pete Millett for bringing it to the DIY community.
This looks like a very interesting and rewarding project. I just had a look at
the designer's site at the link provided at the beginning of this thread. I am
surprised however that the second harmonic distortion product is nearly at
the same level as the third. Why would this happen with a push-pull design,
does anyone know?
On his website, Pete mentions he tested some high-end OPT's which measured better than the Edcors. Could you hear enough difference to justify the larger expense? I bought 2 boards and might build another one using extra-premium components and iron. However, I suspect it will take a disproportionate amount of money to beat what I'm listening to now.
I think the Hashimoto HCW-30-8 or the James JS-6238H might fall into this category. Not exactly huge money for either.
Jeff
For what it's worth, if you have a variac (and even if you don't) and a meter you can determine the turns ratio of the transformer, and with that information we can calculate what impedance will be reflected back to the primary with any given load from the secondary. Here's a page with the maths: http://www.radioremembered.org/outimp.htm
I'm another proud builder and owner of the Millett "Engineer's Amplifier" (DCPP).
I stuck pretty well to the BOM and details on Pete's website, only deviating on the chassis style. I also used 6JM6 (plate cap) Compactrons, mostly because I had lots of them. Pete made a good call spec'ing the Edcor iron; the value is excellent. The quality of the Millett PCB is very high and worth every cent Pete asks for it. It was an easy project given the well-designed layout of the board, and the great documentation available on petemillett.com.
I just am not that thrilled with PCBs in tube amps. It's actually cheaper to build on tagboards or point to point like God and Leo Fender (and some guys in Binghamton) intended.
So it's cheaper....does that make for great sound?
The DCPP could be quite difficult to build PTP, especially for a novice. That is why Pete did a PCB in the first place.
As far as "God" and "Leo Fender" are concerned, they can line up behind Mr. Pete Millett! The Engineer's Amplifier is a top-shelf design and project.