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Hi all, just finished an 18 watt Plexi build. Fired it up, sounds great, except for a very quiet "sizzle" tone on the volume , tone channel. Actually sounds like heavy distortion, only very quietly playing underneath your main tone. It goes away if you turn the tone below 3 or so, but above that it's there. It's only present when the guitar is active/playing. Really only noticeable on clean setting, (Distortion covers it up). If your hand is on strings, muted, no sizzle sound. Any input or direction would be great!
-Thanks -

Nice looking build

That sizzle sounds like high frequency noise.

Try a different tube for that channel to start. Check you grounds, play with the lead dress, etc.

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http://pdfelectronics.com

Clean looking build. if only on VT channel, Try swapping V1 with v2. But If your hand is on strings, muted, no sizzle sound wondering if there is some guitar aspect too.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Played around a bit more today. Started by swapping v1 & v2, didn't seem to change anything. Also swapped guitars to make sure it wasn't introduced by that factor. Also ran it into another cabinet to see if that had anything to do with it, but no luck. I also discovered that if the volume is down around 3 on the amp it goes away also. So in summation at low volume, and low tone levels (3 or less on each) the "sizzle" disappears. I wonder if it is some sort of harmonic? Maybe I will try swapping power tubes, just to eliminate another possibility. This whole issue isn't really a major problem, just an annoyance. I've been so impressed with how quiet the rest of the amp is, and the tones from this thing are amazing. I just want everything to work perfectly. Cranked up the gain about halfway plugged in my SG, and was in AC/DC heaven! I'll do some more research, and look for more possibilities another day. Thank you guys for your input, and suggestions!

dude that's an excellent looking build... nice job

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Corey

Nice build.
One thing i can't see in the picture is the 1meg resistor on the input jacks on the normal channel. (thinks it's the angle)
Only other thing i can think is to check is that there is no DC voltage on the pot side of the capacitors . mili volts ok