Connecting up an F-2B

[jazzyvee]

I'm still experimenting with my F-2B. So I have a couple of novice questions.
At the moment the F-2B is used in Mono mode with the mono output going to my SF-2 in mono mode and then out to my Power amp and single cab.


1) If I am using a mono bass, can I put a patch cable between the front 2nd A channel Input to the input of the B channel so in effect the same signal is being seen by all the inputs.
1) Whist using the mono out for the main amp are the remaining A & B outputs on the back of the F-2B available to use at the same time as the Mono?
2) If so can I put the DI on one of those outputs and a powered speaker on the other?


My instinct says yes it would be fine but I just thought to ask before I dive in head first and fry something. :-)

[JimmyJ]

Hey Jazzyvee,

#1, I think you can link channel A and B together in that way but the signal to B will be reduced because of the summing resistors between the two 1/4" A inputs, if you see what I mean.  But I think it would work.  But why?

#1.5, I can neither remember nor find the actual schematic right now, but my guess is that the mono out is just summing the two individual A & B outputs with resistors.  I don't think using the mono out disconnects either of those two individual outputs, meaning, you can probably use any or all of of these outputs at the same time.  Like, you can probably run in stereo but get a mono feed for the DI at the same moment... That's my guess but i could be wrong.  Gotta ask why again though.

#2, Ahhhh, now I think I might see what you're thinking about now.  Are you looking for a way to have a different preamp tone setting for the DI than you have for your cabinet?  If that is not the case, then the simplest thing to do is #4, put the DI between your bass and the F2B input (like everybody usually does), or #5, if you want to include the F2B tone in your DI send, put the DI between the output you are using and your powered speaker.  Just let the sound-person know that it will be a hot signal.

Also ... mono bass into channel A means you can use the channel A output and not the mono output.  Just sayin'   

Jimmy J

[garyhead]

Still trying to figure #3. Read the post at least 3 times.

[lbpesq]

I regularly "jumper" between the second Channel A input and the first Channel B input (with my guitar plugged into the first Channel A input).  But I do this with my F-2B outputting in stereo to my stereo Carvin DCM200L, and then each channel goes to a separate 1x12 loaded with JBL K120s.  I haven't noticed any weakening of the signal to Channel B.

Bill, tgo

[lembic76450]

I'm thinking to myself don't be that guy, but......
Jazzy,  I used to do this all the time.  Mono bass signal into ch. A input #1 jumper from
Ch. A input #2 to input #1 of ch. B.  Mono out of back to one side of stereo amp to one cab.
The first time I did the it was a revelation of fatness.  Jimmy, I don't believe the summing resistors
come into play because both inputs are being used in ch. A.  The first time I did this was with a Showman
head in the '70s and I continued using the same method with my F2-B.  Try it Jazzy, you'll like it.

[JimmyJ]

Of course the correct answer is - just try it!  My comment about the lower level is based on what I thought I understood about the two separate inputs on the same channel.  That is, at least on Fender amps, there were resistors in line so that if you were to plug two guitars into channel A (sharing it) they would be slightly isolated from each other.  So turning the volume down on one wouldn't change the other, or something like that.  Here's a little pic of the input section of a Bassman.  Note the 68k resistors from each jack before the signal gets to the tube.  So coming in one jack and out the other would put 136k in the signal pathway...

That said, this amount of resistance may have ZERO effect on the level, especially of our active instruments.  But I'm self-taught and in this area of audio electronics so please ignore me.   

Jimmy J

[lbpesq]

Looking at the one-page F-2B manual, the #2 jack on each channel is a 6db pad.  But if #1 and #2 are used simultaneously, the signals are “resistively mixed in equal proportions”.   How this translates to jumpering from channel 1 to channel 2 is far beyond my limited knowledge in this area.


Kenn:  That sounds like an interesting way to set up an F-2B.  I’ll have to try that with guitar.

Bill, tgo

[jazzyvee]

Jimmy, thanks for your insight, and to answer the why? question. I am really just trying to get the configuration with my various alembic bits and basses to get the best sound out of my gear. Once i find that, i will more or less leave things setup.
The thing i find here is that most of the engineers doing FOH at our gigs don't have much experience with mixing the live sound of a reggae band so in a fashion i'm trying to organise my gear so i get to hear the sound i want and be able to give FOH that sound so they have less to do. When we had our own engineer i didn't need to think about FOH.

[JimmyJ]

Got it.  So you want to - for example - give the DI signal a nice juicy bass boost before sending it out to the FOH.  That makes sense.  Of course there's no telling what that engineer might do to your tone once it gets to his desk - he might be tempted to boost highs to get "definition".  Nooooo! 

I once did a club tour where I was relying on house monitors to hear myself.  (It wasn't a terribly loud band).  At one venue we got a nice sound at soundcheck but when the crowd came in the sound man suddenly decided he couldn't hear enough detail in my bass so he gassed up about 1k and above.  The problem is, that EQ also came through my small floor monitor and sounded like an absolute TURD.  Not much fun.

Anyway, Jazzyvee, try what others suggest works fine and link the two channels together, use the A-output in back to run your powered cabinet and use the B-output to feed the DI - easy on the volume of the B-output.  Every PA is slightly different but generally you're dealing with a full-range rig, like a giant stereo.  So if you have a way to test that DI signal from your B-output by running it into a stereo system, powered monitor, or even a small board with a headphone output, you could set the tone controls to best represent what you want to send to the PA.  Then tell the soundperson to try to use it as you have prepared it. 

Jimmy J

[wayne]

One additional note:  I was informed once by Mr. W that if you plug into the mono out, there will be some cross-talk between A and B if they are used as well. 

I was feeding a DI with the mono out and sending separate signals via A & B to different cabs using a Series bass.  Any cross-talk was insignificant for my purposes.

Good luck!

C-Ya..............wayne