F-1X distorting on DI post setting but not full range Out

[edwin]

My new to me F-1X distorts on loud-ish notes on the Post-EQ setting but not on Pre and the full range never distorts.


Since the full range isn't distorting, I'm assuming it's not the FX return jack, otherwise it would be distorting to the full range output.


The post setting on the DI is much hotter than the pre. Could this be the culprit and I just need to back off the input level until it goes away and then do the post setting gain mod?

[jazzyvee]

I have the same situation with both of my F1-x preamps up to last weekend i gigged and had to switch to pre and i rarely have my input gain above the 9:00 position. The sound guy told me my di out was too hot. I do the exercise routine on the jacks now and again but not noticed any change. I am separately experimenting with the output trim pots in my basses to find their optimim level so there may be a common thread.

[gtrguy]

I have not worked on these for quite a while but I am going to blather on with ideas that come to mind. I don't have mine in front of me either.
The unity gain amp is supposed to provide the same level out the amp as comes in, if I read it correctly in the specs.
Can you try another 12AX7 tube to test it with?
Is the DI set up to push more signal, to get it down longer cords, etc, I wonder?
I kinda remember that the TRS output is set up to run a stereo bass in a Bi-amped mode to 2 amps at once.
Are the batteries in your bass fresh or is the blue box working correctly?
I remember that either the F-1X or the F-2B has output jacks that have open/closed contacts on them (inside the case) that may require cleaning with some fine sandpaper on occasion to work right. They are like 'points' on an old car distributer.

Is this the unit you bought from Guitar Center? If so, I think you can return used stuff within 30 days for a refund (worst case)

Anyway, I am rambling. I am sure those with more knowledge than I can come up with better info.
Best of luck,
Dave

[David Houck]

Here is a similar thread from 12 years ago, though I don't know if it's much help.

[David Houck]

This from the FAQ section might be on point.

Post output louder than pre in direct out

[edwin]

This from the FAQ section might be on point.

Post output louder than pre in direct out

This is what I was thinking. However, the distortion is within the DI circuit, not within the mixer input section (my mixer can handle +4 line level and it was far from overloading).

I have come to the conclusion after experimenting that I need to do the output level mod as the post level is clearly saturating the transformer or other circuitry in the DI stage. When I turn down the input, there is no distortion.

Definitely not returning it, it sounds great!

[jazzyvee]

My gig last night I had the F1-x in post mode for soundcheck which was fine but as soon as the first two songs finished, ( they run one into the other), the sound guys came over and told me it was too hot and had cut out for most of the two songs, (my on stage sound was fine), I switched to pre and all was fine. I have two F1-x's and both are giving hot outputs to the DI in post mode. It looks like my first job is to get the mod that David  refers to a couple of comments up and see how that runs. I will try it on on of my pre-amps first and check in the field, although that wouldn't explain the cutting out?
Just to be sure also the send and return sockets where I have my SF-2 is still in the output when the pre-amp is in pre mode isn't it?

[mario_farufyno]

David, you're great.

[edwin]

I did the mod yesterday afternoon with 5 minutes to spare, before I put it in the rack and headed out to the gig with no testing!. Luckily, everything went perfectly and the DI out sound was even better than before, it sounded clearer and there were no crunchy sounds at all. Exactly like the bass should sound (and the front of house mixer loves bass, so it was pretty massive in the room. I like FOH guys who say that the music should sit on a big pillow of bass).

Unfortunately, my car didn't fare so well, and the alternator went in the middle of Colorado nowhere in the middle of a blizzard with the temperature at 25º. One of my windows was stuck slightly open and it got insanely cold in there before  the tow truck arrived. Made home by 5AM. Sheesh. Fun gig, though.

[edwin]

PS. My preamp had the 10k resistor mentioned in the mod picture. At first I was a little confused about which resister that paragraphed referred when it said sub out a 33k resistor, but at the end of the day, I assumed it meant the one that was on the circuit board, so I changed that to a 33k and the "jumper" resistor I left at 10k. But maybe it doesn't matter?

[elwoodblue]

  One of my windows was stuck slightly open and it got insanely cold in there before  the tow truck arrived. 

Brrrr...


Thanks for the tone report...might have to do that with my F-1X.

[edwin]

I think it's worth it. The tone opens up with the volume set higher. At least, that's my experience.

[Zut8083]

Wow.  I am glad everything worked out well.