Peavey KB3 pre-amp blown?

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Peavey KB3 pre-amp blown?

Post by stevensec » Sat Apr 17, 2021 12:07 pm

Hoping Enzo or someone else can give me an opinion...

I was playing electric bass into channel 2 on my Peavey KB3 keyboard amp (60 watt), and was using an ART Tube MP pre-amp to boost the input signal. I had the "Level", "Low" and "High" controls all set to about the 12-o'clock position. At some point, I suddenly lost all bass output from the coaxial speaker - - it sounded like I was only getting tweeter sounds. Although I had not been playing at a high volume, I assumed I had just blown the woofer portion of the coaxial speaker:
peavey KB3.jpg
peavey KB3.jpg (148.12 KiB) Viewed 183 times
And so I disconnected the ART Tube MP, plugged my bass guitar directly into channel 2, and played around with the channel 2 controls. I noticed that I DO still have normal-sounding bass sound, but only if the "Low" tone control is set to the 4:00 position or higher; below 4:00 I get no bass response. The channel 2 "Level" and "High" controls work normally. Channels 1 and 3 work normally.

Do you think I "fried" something in the channel2 low tone control circuit? If so, what is the most likely part? Here is a schematic of the channel 2 pre-amp:
Peavey KB3 Channel 2 Pre-Amp Schematic 2of2.jpg
Peavey KB3 Channel 2 Pre-Amp Schematic 2of2.jpg (90.52 KiB) Viewed 183 times
Peavey KB3 Channel 2 Pre-Amp Schematic 1of2.jpg
Peavey KB3 Channel 2 Pre-Amp Schematic 1of2.jpg (107.18 KiB) Viewed 183 times
and here is the spec for channels 1 & 2:
Peavey KB3 Specs.png
Peavey KB3 Specs.png (179.75 KiB) Viewed 183 times

This amp has been used very lightly, and has never left my basement.

Appreciate your input!!

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