[SOLVED] PreSonus FP10 as Guitar Preamp and then ... wait will that work?

sonicrealism

New member
I've found myself suddenly (pleasantly) the recipient of a variety of boxes, some rack and others not. Numerous options present to configure a home studio. I also have the option to invest in some gear and was thinking about an acoustic preamp and effects. Before I do, I wanted to explore an option I think is in the PreSonus FP10.

Documentation indicates I can use channels 1 and 2 as preamps and then use the preamp out/send to go to effects. The return is to then be into line 1 and/or 2.

I am confused, however. There is a disclaimer that if there is a line in cable present on 1 or 2, that channel's instrument/mic jack on the front will be inoperative.

How does one feed the original analog signal from a passive guitar pickup into the FP10, say on channel 1, such that it's routed out through the preamp out and back in? Setting up the send/return will remove any option for the instrument in?

I'm a novice, so apologies in advance if this is a "d-uh!" type of question. It's got to be something simple I'm missing.

Thanks.
 
The pre-amp in and outs on the FP10 only work on the mike inputs. If you plug a guitar lead into channel 1 or 2, you won't hear anything, because, as they say, using the in and outs disables the instrument input (for a reason that I cannot figure out).

One way around it is to go from a guitar into a DI, then XLR from DI to XLR in on Channel 1 or 2.
 
Appreciate your engaging here. Per the manual, channels 1 & 2 on the front are mic/instrument, with line in on the back. Line in takes precedence and if used, will disengage the front mic/instrument inputs. All other channels are on the front either mic/line level (not instrument). There's further discussion that non-active instruments should go into 1 & 2 on the front, and active use line level on the back. Putting a non-active instrument on the front bypasses the mic preamp and "the FirePod becomes an active instrument preamplifier" (pg 15).

"Ah-ha!" says I. "I can use it as a guitar preamp and look at other options for my limited cash!" My thought here is to check out using it as a guitar preamp, send to an external effects units (Alesis MicroEQ and Quadraverb ... I'm experimenting and learning) and then return it to channel 1 for A/D conversion and then out to the DAW.

My confusion comes from the simple fact that plugging the effects loop back in the back using that same channel's line input neuters the FP original channel input. Where is the effect send signal to come from ... unless is is a blend of all channels ... except 1 or 2?

Your comment, above, got me to thinking and I went back to the FP instructions. The example setup on pg 19 shows a bass guitar and mic as as input on 1 & 2 front panel, no effects. It also shows an electric guitar to an effects unit and then that feeds the FP on 8. The effects unit would be an line level input, I believe. That tells me the unit does indeed support 8 line levels and optionally 2 that are instrument needing a preamp stage (1 & 2 on the front). That sample setup didn't speak to using the preamp out send/return option.

To your last point, yes, I am considering a DI. I need a preamp. I also value good parametric EQ. I also plan to shape/color my acoustic guitar's sound. If I can make the FP act as the preamp, that shifts the investment into more of the sound shaping/coloring. (I'll eventually need a preamp outside the rack, but not anytime soon). For what it's worth, I am looking at the LR Baggs Venue but the Session has some really nice effects but not the EQ or tuner.

Again, thanks for helping here.
 
Boggled! No matter I am sure you will get it done if it can be done!

Just like to say? The acoustic, does it have a passive peizo pickup? If so I wonder if you know that these need a very high input impedance pre amp, 5 meg Ohms, better 10 rather than the "magic meg" for electrics. There are of course many such preamps on the market but all, afaik, are bloody expensive (don't know why, only one 'fing resistor!).
If you are at all handy with a solder iron you can make a 10 meg buffer with few Cs&Rs and a TL072 or even easier with a single FET. Such a buffer then feed the rest of your instrument preamp chain.

Dave.
 
Well, it's reassuring when others are stumped and don't have immediate obvious solutions! I ran this by a musician friend last night and he was likewise puzzled. He did suggest bringing the effects return as an input on a different channel. That still leaves the basic puzzle in place to solve, though.

Interesting thought on the impedance. I'd not registered that consideration. Yes, it is a piezo, a Martin Thinline from ~30 years ago, purely passive. I like the sound. To be honest, aside from the challenge of the FP puzzle just because it's there to be solved, I'll probably go ahead and get a good acoustic preamp.

I could try making something as you suggest, but that would take more time and effort than I want to put into that type of thing. I'm an electrical engineer by academic training and would want to understand designs, think through build, layout, etc. I'd rather be working the sound chain itself, understanding the A/D/A options and what I can do in a DAW.

I also want to train my ear more on the backside of the chain. I've started running sound for my church. I'm repeatedly told that whatever I am doing with eq, gain, mix, etc, to keep doing it, that it is sounding great. I need to make what I do more "systematic". I've had gear made available to me to help do exactly this ... which led to the original post for the FP10.

Thanks again. You've fed my thinking on the use of the FP as an acoustic preamp.
 
Ok Sonic, as you will but since I am sure you can solder it would take you about an hour to knock up a 10 meg buffer in a baccy tin across two jacks with 2n3819 JFET!

No need to think it through, just a bog standard source follower, 100% NFB so low distortion and unity (ish) gain.

Dave.
 
Ha! Well, I may give that a go ... once I get the various other things in this setup figured out.

To close out this thread, I wanted to post a "solved it!" response. Turns out I was assuming the PreSonus manual would spell out all nuances that a novice, like me, would needed. Not true. The manual is not wrong, it's just not throughout complete spelling out all implied behaviors.

The missing piece of information that came to me on the umpteenth read was that the instrument-in would always continue to present at the preamp out even if the line-in had an insert. Line-in does indeed take precedence over instrument-in but the instrument-in signal is still there to leverage. Thus, you do indeed have an effects loop per their description.

I'd not hooked things up when I first posted, thinking I could do enough up front reading to know what to do. Sometimes you just have to go and try something to really learn. (I guess that's why there are mandatory "labs" to take during education.)

Thanks again for the thoughts.
 
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