[Music in a bottle]

Some transistorized preamps have an output capacitor that can send a DC charge to the following amplifier, abd sometimes they shorted, and some power amps have no input capacitor that will nullify the defect. So, you can turn the preamp on first, then the amp and not get the thump which can still easily blow out a speaker. You can wire in a capacitor between the input jack of the power amp and it's first stage of amplifiation. And just what value should you use? The answer is "it depends." I would personnally start with an .05 mfd 620 volt and see how it sounds. I assume that both machines have, or have been converted to proper 3 wire grounded recepticles, and the "death capacitors" have been removed. Use crap speakers and resistive loads in parallel when trying out these tests, and let us know what you find.

I'm using a model 7t marantz, and I need to look at the schematics of the amp, but I believe the input dumps into a capacitor. By the way guys, the thump I was hearing, is actually a loud audible AC buzz that instantly went to a hum, then silent. The sound was noticeable at the main electrolytics, and never came through the speakers. Since I changed the caps out with a set from one of my parts rigs, the amp still makes that sound, but not nearly as often. Probably 1 out of every 6 times now. Would it be wise to simply plug it into the wall recept, several times to see if I can figure out if it is the preamp? My preamp has outputs for an osc. which I have one hooked up, and at power up, there is no visable trace on the scope other than the flat line of the sweep. I also had the scope hooked to the numerous amplifier outputs, with no spike or fluctuation of the flat line sweep, again. According the original literature that I got with these amps, the caps are phone company grade. What are the chances of getting replacement caps that have these same characteristics with threaded post's for wire hook up, like the originals? If you have never seen vintage marantz gear, you should treat your eyes. They are real works of art in my opinion, much like the old Philco radios! I'll try to get some photos up here for you all to view.