MILA-1 finally done... now how do I track down that "spike"?

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babyhead said:
Shouldn't an unbalanced signal go straight into the DI?

Probably... but my tone generator (unbalanced) makes this thing freak out, so I'm assuming I have something wrong on the way in cause this should work without adding noise, right?
 
[quote author="dustbro"]I now have the power inlet and B- from the power supply meet at one point on the chassis, and the rest meeting at another point on the chassis. the hum is now completely gone[/quote]

Interesting...if you short the two star points with another wire does the hum come back?  Based on your description you are using the chassis to connect the two star ground points.

I can't tell from your pics...did you run a shielded cable from the DI input to the connection to the first tube?  Or are you even using a DI jack?

 
Matador said:
Interesting...if you short the two star points with another wire does the hum come back? 

It does come back... but only when there isnt anything plugged into the input. If anything is plugged into the input, the tiny bit of buzz and hum go away. Going to have to check my grounding scheme a bit more.

Here's what I got sending a 1kHz tone thru the amp when the gain turned up. Looks like there are harmonics all over the place. These follow the tone as I sweep thru any range of frequencies. Is this normal?
The amp also sounded dark with a dynamic mic plugged in, but sweeping tones with my generator shows that its pretty flat from 20hz to 20k. I also see that there is still a bit of 60hz in the amp, but I dont really hear it.
mila1k.jpg
 
dustbro said:
It does come back... but only when there isnt anything plugged into the input. If anything is plugged into the input, the tiny bit of buzz and hum go away. Going to have to check my grounding scheme a bit more.

That's to be expected, when your input is not shorted to ground on disconnect. But who cares what it sounds like when it's not hooked up to anything.
 

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