Strange Amp Issue, No Sound With Active Bass

[deluxeg]

After fixing the bias issue in my Ampeg SVT3 I thought I was done, it sounds great and had good volume with my 70's Classic Jazz. However tonight I plugged my Fender MIM Jazz Deluxe in which is an active bass. I got zero sound, I turned up the gain and master all the way and I could hear my bass very very faintly in the speakers. Changed the battery in the bass, same issue. I plugged in some other basses, all passive, and could hear them fine. Then I plugged in my Pod XT into the power amp in in the SVT and my bass into the Pod, same issue couldn't hear it. Tried the active bass in a TC BG500 and a Micro-VR and could hear it fine. This has me stumped.

[deluxeg]

I also tried sending the SVT3's preamp out into the Micro-VR's return jack and same issue can't hear the active bass, but can hear my other basses.

[BassmanPaul]

You are not using a TRS cable are you??

[Swampman Cory]

Try plugging into a tuner. See if your bass reads there. Maybe there's a problem with the input jack on the bass.

[deluxeg]

I am using instrument cables from monoprice.com tried two different cables and I can hear the same bass in my other two amps using the same cables.

[deluxeg]

Well I feel dumb, I was just able to try a Fender California cable instead of the monoprice cable, and what do you know? Sound! It turns out the cables I ordered were TRS cables!

Why would these cables work on my other amps and not on the SVT3? Thanks for the suggestion BassmanPaul.

[B-string]

We've seen it before, the ring is not in the ground path.

[BassmanPaul]

With an active bass the output jack is a TRS. The negative pole of the battery supply connects to the ring. When a regular TS cable is inserted into the jack the ring and the sleeve are shorted together switching on the pre-amp.

If the input jack of an amplifier also causes the ring to sleeve short then the pre-amp is again switched on.