IN-2 woes

[edwin]

OK, this thing is awesome, but I'm encountering some very weird behavior. Admittedly, I'm trying to stretch the boundaries a bit, but still


So, I have it wired like this:


Bass to 5 pin input
Front panel outputs to front panel inputs of F-2B
Rear panel outputs of F-2B to returns on back of IN-2
DIs to PA
Rear panel output to power amp


My understanding from examining it is that when you plug something into the rear input, it breaks the normal to the DI and output, so that the F-2B plugged into it is sent to the PA and the amp.


All is good, sounds great, etc.


However, when I plug a different bass directly into the front input of the F-2B, it goes to the power amp but doesn't go to the DI.


And then, when I hooked up my F-1X to run the other bass, which, of course, worked and sounded great, it wouldn't see the front panel output of the IN-2 when I tried to use the Series equipped bass through the F-1X.


The whole thing is blowing my mind.


I work as a professional engineer, so I think I understand signal flow and how switched normals and half-normals work, but something is very weird here.


Any ideas here?

[JimmyJ]

Hey Edwin,

Is that IN-2 stock?  I have one that over the years I've modified so many times that I have no idea what jack is connected to what...

The last line of your routing description says:
"Rear panel output to power amp"

Rear panel of which piece, the IN-2? 

If you have the stock wiring, the "return" jack on the back panel does as you describe and uses the direct box section as a standalone piece.  In other words it "detaches" from the IN-2 audio path. 

So you say:
IN-2 front panel outputs (the "s" infers you are running stereo) to the inputs of your F-2B. 
Rear outputs of the F-2B (still stereo?) to the "returns" of the IN-2 sending through the transformers and out the front panel XLRs.  So you are going stereo A & B to the PA, right?

Now... if you are feeding your power amp from the rear panel of the IN-2, your F-2B is not in the circuit driving that amp......  that can't be right...

Questions:
Are you running the IN-2 selector switch in stereo mode? 
Are you feeding both IN-2 outputs A & B to your F-2B inputs A & B?
Are you running the MONO output from the rear panel of the F-2B to a return to use the DI box / and the A & B outputs of the F-2B to your power amp?
- or -
Are you running the A & B outputs of the F-2B to both returns, and out to the PA?

If that's the case, then how are you getting to your power amp?  And is that also in running in stereo?

We might have to get you to take the lid off the IN-2 and post a pic.  Ha!  As I said, it's also a really handy piece to modify to do any crazy routing you can think up.

And I'm gonna need a pencil and paper to work on this!

Jimmy J

[edwin]

Thanks for the reply.

Your routing is correct. However, I think that the output of the F-2B, returned to the IN-2 on the back panels, sends the signal from the F-2B to the IN-2 and then on to the power amp via the IN-2 output back panel jacks because the return jack has a switch built in to it, where the signal from the return jack gets routed to both the DI and the output jacks. At least as far as I can trace the wiring.

Are you running the IN-2 selector switch in stereo mode? 
Yes.

Are you feeding both IN-2 outputs A & B to your F-2B inputs A & B?
Yes.

Are you running the MONO output from the rear panel of the F-2B to a return to use the DI box / and the A & B outputs of the F-2B to your power amp?
- or -
Are you running the A & B outputs of the F-2B to both returns, and out to the PA?

I've done both. Still experimenting. The latter obviously works better.

I think I need to get back under the hood and see exactly how it's set up. It might need some mods. Weirdly, it seems like it's acting as expected in some cases and not others. When I first got it, I hooked them both up in my studio and the signal flow (i.e., the F-2B output) behaved exactly as I expected and appeared at both the XLR and rear 1/4" outputs as I expected. It only got weird on the gig.

I did have to accept a mono signal (neck pickup only) onstage as my amp is not in stereo (although I could bring another cabinet).

This past weekend, I tried running it stereo in/mono out (i.e., stereo front panel IN-2 outputs to front panel F-2B inputs, mix out of F-2B to single channel return and then DI of that side out to PA and 1/4" to amp but that behaved oddly, too. The amp was getting both channels, but the DI only got the channel corresponding to the IN-2 input channel. Confusing. I had thought that plugging into the return broke the normal there.

[JimmyJ]

Hey Edwin,

Thanks for the reply. The way I remember the circuit (and it’s been a long time so I could easily be wrong) is that with nothing plugged into those “return” jacks the “dry” signal from the bass currently plugged into the 5-pin input is passed directly to the transformers and out the xlrs to the PA.  Mirroring whatever mode the selector switch is set to (stereo / mono)


Plugging a 1/4” cable into the “returns” interrupts that “dry” signal and sends tip and sleeve of that cable to the transformer, and on to the PA.



But the rear panel “output “ jacks remain as normal. They should still be sending the dry signal from the bass currently plugged into the 5-pin cable.


I’m pretty sure that’s the original wiring scheme, perhaps to reach some gear in the rack with rear inputs, like a tuner...  But as I said, the IN-2 is an ideal box for modifications to fit whatever you can dream up. Think various summed mono outputs while still running your stage rig in stereo, etc., etc...


Jimmy J

[lbpesq]

In more than a decade of hanging around this forum, this is the thread I have understood the least.  You guys should get a room!

hehehehe

Bill, tgo

[edwin]

Whatever happens, I'm imagining a bank of mini toggles on the back of this thing before I'm done!

[jazzyvee]

I'm currently reading through these IN-2 threads to find some reasoning behind my current issue with an IN-2.
This thread has my brain in circles.

[JimmyJ]

Jazzeyvee,

Can you point me to your thread - or describe once again the routing you are trying to get to work.  I saw your note about having a feedback issue so just trying to remember what you're trying to do...

Jimmy J

[jazzyvee]

Jazzeyvee,

Can you point me to your thread - or describe once again the routing you are trying to get to work.  I saw your note about having a feedback issue so just trying to remember what you're trying to do...

Jimmy J

Sure Jimmy.
https://club.alembic.com/index.php?topic=26122.msg267164#msg267164