Markbass F-500 arrives--and an issue arises

[mindwell]

So the F-500 arrives today. I get it home, unbox it, hook it up to Bag End S-15D, power up, and plug in my Sadowsky Metro M-24. Everything is flat on amp, and it sounds great. I pull up the VTC knob, to take the bass from active preamp to passive mode, and the signal from the preamp farts and dies, and the smell of burning capacitors wafts from the amp into the room.

I power down immediately and then restart the amp. It seems a bit balky at first, but then signal resumes. I play it on active for a couple of minutes, adn then test it by taking down preamp volume, unplugging, pulling up VTC from active to passive, and then plugging bass back in and bringing volume back up. Amp sounds fine and seems to work.

So it sounds great, at least at "don't wake up the sleeping baby" basement volume, and appears to be VERY responsive and alive. But did I barbecue the input jack, and does it need to be sent back during the 30 day trial period? Seems odd that a realtime preamp change on the input side should produce such a dramatic result...

[MIJ-VI]

"...and the smell of burning capacitors wafts from the amp into the room..."

I'd send it back.

[fleabee]

Send it back asap. Don't dare to even open it.

[Kwesi]

Originally Posted by fleabee

Send it back asap. Don't dare to even open it.

hells yea.

[unlined4string]

Magic smoke BAD.

[mindwell]

True dat. Still, just spent the last hour playing it at low volume, and it sounded and responded fine. No weirdness, and the electrolytic smell is gone. Seeing as how I'm only on day one of the GC 30-day trial period, I'll play it at gig this weekend as planned, and return it on Monday. In the meantime, if any tech folks would like to surmise why a drop in preamp voltage caused the buffering / gain weirdness, I'll be all ears.

[Munjibunga]

Even as an electronics tech, I was never able to differentiate the smell of a burning capacitor from that of a burning resistor.