F-1X direct out question

[crgaston]

My sound engineer has never let me use the post setting on the DI of my F-1X because it distorts like crazy. I have had it over 10 years, it was that way when I got it, so I just figured the post signal was too hot for the board.  To see if the effects loop is present in the pre setting (it is), I ran a mic cable from the direct out to my amp tonight, and it is putting out almost no signal, compared to the full range out on the back.  In the pre position, it was clean, but in the post setting, it was definitely breaking up.  Not just distorting, but making hideous pops and crackles, even though it was still barely audible through the amp.  If I had had my amp gains set like that and had been running the full range out, stuff would have been falling off walls...next door. Is this right?  Can anyone explain?
 
I ran this test with the preamp gain at 2.5, plugging an 18V Bartolini-equipped Modulus with the eq flat.  The SF-2 was in the effects loop, but the problem occurred even with the filter gains off.  It exhibited this problem before when I was running nothing in the effects loop.  Actually, that is incorrect- I always ran my tuner from the effects send.  During this test, the tuner was plugged into the highpass crossover out.  I have a little multimeter and can provide voltage readings if someone tells me where to put the probes.
 
Thanks,  
Charles

[David Houck]

Just out of curiosity, unplug the tuner from the highpass crossover out and run the test again.  Probably not it, but worth a try.

[crgaston]

OK, I think there were 2 issues here.  One is that the preamp was being overdriven, the other was a bad mic cable.  I think everything is as it should be, just disappointing that I'm running out of headroom on the DI out before the mono full range out.

[David Houck]

You might try plugging the Modulus into the second input rather than the first.  The second input has a 6db attenuation, so that might address the problem of overdriving the preamp.