mike stehr Posted October 13, 2003 Share Posted October 13, 2003 It works, haven't had a chance to listen to it yet. $54.00 with shipping from Ebay, and a little labor. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted October 14, 2003 Share Posted October 14, 2003 http://forums.klipsch.com/idealbb/files/Train%20show%20027.jpg Great little amp, Mike. NICE. Give it a listen as you know, some of these early dinky trans can be magical in the mids. MY guitar amp buddy has a load and we listened to a few last time over to his studio (the swine has my drum kit). I do agree with Ryan in that some new quality PP trans would really bring some good things but bet you will enjoy the little tikes a lot, especially via the CW. You might not even WANT to replace. kh Quote Link to comment Share on other sites More sharing options...
Deang Posted October 14, 2003 Share Posted October 14, 2003 What is it about the transformers that won't let them go to 20Khz. Isn't this from the same time period as the Eicos and what not? Geez Mike, the tubes are probably worth $50. Nice job. Quote Link to comment Share on other sites More sharing options...
jazman Posted October 14, 2003 Share Posted October 14, 2003 Mike, SWEET looking amp! Klipsch out. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted October 14, 2003 Share Posted October 14, 2003 Most of these amps were designed to power less then stellar speaker systems in consoles so the response curves were designed to match the speakers they were powering. Like ryan suggests a nice set of Iron would do wonders for a amp like this. Craig Quote Link to comment Share on other sites More sharing options...
mike stehr Posted October 14, 2003 Author Share Posted October 14, 2003 Right. The amp was designed for old open baffle consoles with 12 inchers with stiff cones. When I got the amp, I visited my retired EE friend and gave the amp the bench test. It passed. All the coupling caps were OK. The coupling caps are .0015 uf Ceramics, and 0.047 vintage Sprague orange drops. These were the caps that was in the amp. The ceramics probably are stock. Dan and I went around about the orange drops, he thinks they were swapped. They did a helluva job. No electrolytics under chassis, just the multisectional, which includes the cathode bypass cap. The Balance pot was daisy chained to the external receiver or whatever, which is part of the feedback loop. (With a couple of resistors to ground, possibly.) So the amp had too much input gain, and made the output a "Bucking Oscillator". A couple resistors fixed that. I had some .1 Polystyrene and tin foil Relcaps or sumthin' I swapped out for the .0015 uf coupling caps. I still need to replace the old orange drops, maybe more Polystyrenes. The old multisectional hums just tad, what would be expected, it will hang for awhile. Gee, don't condemn those ugly little OPT's so quick. On the bench, the amp mangaged full power at 20 hertz. 8 watts, one side as measured on a scope with a generator. They have bass on the Cornwalls. I'm pretty sure the amp will do better than 10K, but I understand the OPT's themselves won't, not without the feedback loop. http://gabevee.tripod.com/maggie.html Take this guy's info with a grain of salt, he's no engineer, but doesn't claim to be one either. I think Gabe recs a 6000, 6600 ohm OPT with UL (screen winding). Which makes sense, since it's a Paraphase Inverter circuit. Magnequest has a Dynaco copy I think, but I'd rather shell my cash on the 300B amp and find parts for a pre-amp. Ol' Dan is going for a Magnavox clone, he needs one more Olson brand 6K OPT. Looks like a Tango or Tamura. Prepared to be apalled by the quasi self-bias scheme. I do have wiring pics, it ain't nuthin' special. Quote Link to comment Share on other sites More sharing options...
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