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Even More Adventures with Wire....Eico HF-81...

Hi,

So this integrated amp has its 12AX7s and 12AU7s all operated conservatively at under 1 mA. per section. It is wired stock with bell wire, flimsy stuff.

I ended up, as of two weeks ago using 12 gauge aircraft or mil spec wire, pure silver stranded, and a 30 gauge continous cast copper ( long grain ) magnet wire in parallel with the 12 gauge silver, to all B+ wiring distribution points in the amp.

This was a pretty good compromise, and way better than the stock amp's PUny wiring. But, it STILL was not totally capturing dynamic peaks with absolute integrity and ease, as I heard it on playback with my JBL D-123 speaker.

I added some special Mr. Dave Slagle-approved Radio Shack jumper wires :-) across the newly added silver B+ wiring, and I HEARD a need for an even greater gauge than 12 gauge ... to cut the mustard even moreso.

As of now ( and I am done with the HF-81 ) I ended-up using Fulton FMI Brown speaker wire, which is about 10 gauge, for all the B+ wiring, and also some about 30 gauge CCC wire from Dennis Boyle ( Chrimera Labs ) IN PARALLEL with the 10 gauge speaker wire. Now realize audio DIY friends, this is 10 gauge B+ wiring going to tube sections running under 1 mA.

While the present modded HF-81 has endearing qualities, I just can't hack listening to it long term, due to its lack of a totally separate G2 supply.....something I like in pentodes. The modded Paoli 60Ms of mine had this G2 optimized in such a way...no comparison between the two pentode stages' resolution, the Paoli wins easily.

I think its time for me to take the 2007 lessons learned with wire in the Eico HF-81 and apply it to a low mu triode output stage amp. A two-stage DC-coupled P-P Lofin White variant I've had in mind for a couple of years, a single 6SL-7 with round plates, DCed into a P-P pair of 2A3s with no negative supplies, no constant current sources, etc. A Zen-like super-simple / honest amp. Gee, I could even strip-out my old ARC D-75 and build it in that chassis reusing the old ARC iron !!

Did you all know that the ARC D-75-76 amplifier series had power trannies ( thirty years ago ) rated 800 mA and ... WELL under 5 ohms DCR? ... Measure one ! Wm. Z. knew, back then... was and is .... no fool.

Now I need to order four 2.5 VAC at 2.5 A. dual bobbin Hammond Ef power trannies for those four 2A3s next !! Ahh, the useful 2A3, Jeff's old friend - along with the 45.

Jeff Medwin


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Topic - Even More Adventures with Wire....Eico HF-81... - drlowmu 20:35:42 04/17/07 (40)
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