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About Skizzly

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  1. Its a Carvin X100B amp and it uses EL34s for the power tubes and 12AX7s for the pre. I will measure the bias tomorrow when I am back in the shop.
  2. I checked it out a bit more and found a ~4Vpp sawtooth wave on the power rail, which was also visible on the OT primary windings, so I am guessing one of the power filter caps is leaking. Its the original caps, plastic wrapped electrolytics, so they probably should be changed anyway. I ordered some replacements so ill check back in when I get those installed. You all think thats enough noise to cause this weirdness? No 60hz hum, just weird volume/distortion problems. I also have some spare 12AX7s laying around, this amp uses three in the preamp section which i have not changed yet.
  3. Hello I am trying to troubleshoot a tube amp I got from my friend. He says it was very distorted and strange when he would play it. When i opened it up I found that the PCB had gotten so hot that some resistors across the tubes had desoldered themselves and fallen out of place. This was an easy fix and I replaced them with new ones of the same value. I also replaced the power tubes because I assume the old ones were not happy after all of this abuse. I have a set of 8ohm speakers that I wired up in series and connected them with the OT set to the 16ohm winding. The sound that came out was HEAVILY distorted and had volume spikes associated with how hard i would strum. It sounds like a noise gate opening up, with some bit-crush level breakup and artifacts. After this I tried connecting it to two 8ohm wirewound resistors, also connected in series, so I could run a function generator into it and inspect the output with a scope. Sure enough it folded the {censored} out of the waves and it looks like a heavy distortion effect. Also i noticed the amp would create its own whine in the same freq as the input from the function generator. Is this normal for tube amps? I am a certified electronics tech but i an not very familiar with tube amps, any help would be greatly appreciated! Thanks, Skizzly
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