OTL Asylum

My experiences with new M-60 Mk.3.3s, good and not-so-good

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1. First, sound quality--resolution/transparency and smoothness (= nonedginess)--is excellent, even with brand-new everything.

2. Have had some problems with lack of good contact with tube sockets. Had lots of trouble getting one amp to null its DC offset. Thought it was mismatched output tubes or even bad frontend tubes. Played with 16 output tubes (hereafter OT or OTs) and several frontend tubes (FETs)--original Chinese and old Tung-Sol roundpates. Sometimes the cathode follower's filaments wouldn't glow. Eventually worked out a system of loading input tubes into the amp and then pairs of OTs, and all has been well in both amps for a couple days. (I experienced the problems in only one amp, I experienced NO OT-internal-fuse blowings, and Ralph was very helpful.) My lesson learned--TY, Ralph--is that the Chinese tubes have slightly larger pins, and sometimes the socket's contacts don't make good contact with my old tubes.
3. Have installed new Cardas CCGR bindingposts, new solid-silver wires to the cap terminals, a new Furutech FP-901(R) RCA jack, two 1uF SoniCap Platinum output-stage-PS bypass caps, and three strips of SoundCoat the thicker...see link...on the bottom cover. IMO the chassis rings too much, and I'll be adding more of that stuff. (IMO vibrating resistors, capacitors, wire, vacuumtubes, etc., do NOT add to the sound quality, they all diminish it.)
 photo 2016Apr23_SoundCoat on bottom_1500h_zpszliczxck.jpg
I got SoundCoat inside the very-highly-ringing transformer cover on the 2nd amp.
 photo 2016Apr23_SoundCoat inside T-cover posts and RCA_1800w_zpsh9p5lmpg.jpg
This cover is now DEAD!

4. I THINK the first serious improvement project I'll do is to replace the inexpensive 100/350 'lytic caps in the frontend's powersupply with BlackGate VK-series 150/350s*, bypassed with 0.47uF Platinums. ... But that's a big project, and probably it'll take me weeks to start that. Then I'll replace the output-stage PS caps, and for that I have a bunch of BlackGate 470/160s*.

BTW there are no feet on my amps; I'm using the 2"-square Wagner antivibration pads...
http://www.audioasylum.com/audio/tweaks/messages/20/200726.html
...two-high. They seem to work just finely on my carpeted concrete-slab floor.

* that I've been saving for many years

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Tin-eared audiofool, large-scale-Classical music lover, and damned-amateur fotografer.
William Bruce Cameron: "...not everything that can be counted counts, and not everything that counts can be counted."



Edits: 04/23/16   04/23/16   04/23/16   04/23/16   04/23/16   04/23/16   04/24/16

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