Author Topic: 1200s HUM question  (Read 7097 times)

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Offline usersunn

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Re: 1200s HUM question
« Reply #14 on: October 01, 2009, 07:28:57 pm »
Just to give an update-Its almost three weeks since I sent in the 1200s for a full recap/ new power cord/4 ohm tap.....My tech had to order the higher voltage caps, he didnt have any 525 just 400v caps...Ill let you know how it turns out soon!

Offline usersunn

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Re: 1200s HUM question
« Reply #15 on: October 06, 2009, 12:22:55 pm »
OK..... Got the '69 1200s back... Had 15 total caps replaced!(mostly Sprague orange drops; the filter caps Im not sure of the brand..), new 3 prong cord, 4ohm tap added instead of 16 ohm...It sounds just as good if not better (tighter, punchier, fuller upper bass and low mid response) , still has the glassy high end, which by the way is due to the old Mullard 12ax7 in the preamp slot... (The new EH 12ax7 I tried in its place sounded horrible... lost all the hifi sound....theres like an extra octave or two of high end with the Mullard, and a creamier,livelier "feel", ...In addition, I didnt hear any change in the tone controls from replacing those old long green tone caps with the orange drops...Also, the amp was underbiased, (tubes ran very hot)we backed it off a bit and the amp sounds great with even less pronounced hum now with slight overbiasing, and the amp runs cooler. There is a slight hum, but Im thinking theres always gonna be a little...Anyway, amp should be good for a while, only question now is whether to leave the vintage 6550's in there or try some new Tungsols or something......what a rockin' amp!!