Buffered Boss pedal in front of Axe FX

[charliepratt]

I know this discussion has been had a few times, and I may be operating from bias here... but I have two 10-ft Mogami cables in front of my Axe FX III, with an inactive Boss OD-3 in between (It's my favorite subtle OD, and I add it onto certain presets at various times).

When I plug straight into the Axe FX, it's great. When I plug in with the Boss OD-3 acting as a buffer, everything sounds...better to my ear. I have pretty high end Neumann monitors set up in my studio and have tested it in Logic.. I don't hear any unwanted noise when I include the Boss pedal in the chain in front. And to my ears, everything sounds just a bit brighter and with the kind of clarity I like.

Do I need to just pull the OD-3 out of the chain, and adjust my presets accordingly? Or is the buffer in the OD-3 actually doing something pleasing that I can't get otherwise?

Thanks @FractalAudio. You guys seriously rule.

 

[Budda]

Post an a/b.

 

[Greg Ferguson]

Do I need to just pull the OD-3 out of the chain, and adjust my presets accordingly? Or is the buffer in the OD-3 actually doing something pleasing that I can't get otherwise?

It's providing a high impedance load which helps maintain the frequency response of the pickups through the cable to a regular amp, but the FX3 and FM9 are smarter than an amp, and let you set the impedance in the Input 1 block. From the FX3 manual:


Input impedance in the Wiki says:

Using a buffer before the instrument input disables the auto impedance feature.

"A buffer will render the impedance stuff ineffective. It will also add (maybe considerable) noise which may defeat the low-noise advantage of the front input." [11]

I'd try it without the buffer and set the Input 1 impedance on Auto. When I was running a pedal board in front of my tube amps I'd always use a buffer, but I find I get amazingly good fidelity straight into the FX3, many times I've been wow'd by the sound.

 

[charliepratt]

Thanks, I’ll try that. I have a suspicion that because I’ve always had that pedal in front, that I’ve created presets that are eq’d darker than they should be, to compensate for the brightness the buffer adds…

 

[mr_fender]

Tone match the OD-3 in the bypassed state against a straight cable and see if the resulting IR curve is anything but flat.

 

[App12]

If you like what it does, keep it! What’s the harm?

 

[strabes]

Without knowing the exact schematics of the OD-3, there's two things that could be causing this off the top of my head:

1) Capacitance difference in the two cables. If the two cables are identical then this is not an issue. However if the cable between the buffer and FM9 has a higher total capacitance than the other, when you remove the buffer and connect your guitar to that cable, it will roll off more high end than was rolled off by the other cable before it reached the pedal. You mentioned they're both 10ft but if one has a higher capacitance per foot then its total capacitance will be higher.

guitar ------ buffer --------------- FM9 = less high end roll off due to the lower total capacitance of the first cable (buffer "eliminates" the high end roll off of the higher capacitance cable)
guitar --------------- FM9 = more high end roll off due to the higher total capacitance of this cable

2) Boss' buffer design in this particular pedal. They use many different buffer designs, some actually boost the high end and are not bypassed with the pedal. This would be pretty easy to test with TrueRTA or other utilities as has been mentioned above.

If it’s neither of these then I am stumped.

Also let's get an OD-3 model in the Fractal! It's a great sound, one of Boss's underrated gems.

 

[Wired]

Also let's get an OD-3 model in the Fractal! It's a great sound, one of Boss's underrated gems.

I have one of these. It’s a nice pedal.

 

[charliepratt]

So, after some careful swapping and listening, it's clear that one of my cables just sounded better than the others. I was able to remove the OD-3 from the front of the Axe Fx III and it sounds great. Thanks to all for the good suggestions and insight.

That said, please, pretty please @FractalAudio, can we get an OD-3? Justin Derrico agrees. Truly unique circuit and a secret weapon of many guitarists—worthy of inclusion into the Fractal family.

 

[guitarcal]

That said, please, pretty please @FractalAudio, can we get an OD-3? Justin Derrico agrees. Truly unique circuit and a secret weapon of many guitarists—worthy of inclusion into the Fractal family.

+1, I would second this!

 

[Greg Ferguson]

So, after some careful swapping and listening, it's clear that one of my cables just sounded better than the others. I was able to remove the OD-3 from the front of the Axe Fx III and it sounds great.

Excellent diagnosing sir!

 

[marsonic]

So, after some careful swapping and listening, it's clear that one of my cables just sounded better than the others. I was able to remove the OD-3 from the front of the Axe Fx III and it sounds great. Thanks to all for the good suggestions and insight.

It's actually shocking to me how different guitar cables can sound. I'm very much not a "cables matter" kind of person...except for guitar cables before the first buffer.

I was going to suggest some good relay-based bypass pedal (e.g., gig rig quartermaster) to isolate the different things. I have a QMX-2 that I've mostly used for swapping between chains to quickly hear the effect of things like buffers. At some point, I set it up so i had a very short cable from the guitar to the QMX, 2 different 18' cables in the loops, then a short cable to a buffer I knew (from previous testing) didn't have a sound, then a cable to my fractal. And it wasn't ambiguous which long guitar cable I preferred (and I was 100% on picking it blind).

That being said....the difference between cables is all in the high end. They act as low-pass filters; any other effect that people claim about cables....is wrong. Unless it's broken.

 

[FractalAudio]

They act as low-pass filters; any other effect that people claim about cables....is wrong. Unless it's broken.

They actually don't act as lowpass filters. They act as a capacitor. If your source resistance is high then you'll get a lowpass response. If you have a low source resistance you can run hundreds of feet of cable with no high-frequency loss. That's why buffers exist.

Everything else, though, yeah, it's a bunch of snake-oil BS.

 

[marsonic]

They actually don't act as lowpass filters. They act as a capacitor. If your source resistance is high then you'll get a lowpass response. If you have a low source resistance you can run hundreds of feet of cable with no high-frequency loss. That's why buffers exist.

Everything else, though, yeah, it's a bunch of snake-oil BS.

Yes, that is more correct. I meant the only effect that a cable can have is that of a low pass filter....or an open circuit.

For a guitar, it's the high output impedance of the guitar (and the inductance of the pickup) that, in conjunction with the cable, creates a resonant LPF because that circuit is an LRC filter between source (pickup hot) and ground.

My crack at the end was about people (even otherwise very talented audio engineers) who say things like different ethernet/usb cables somehow sound different or that some specific $1,000 per meter line-level interconnect preserves more detail in the midrange. That kind of comment can be completely ignored....even if the same person's advice about how to set an EQ or compressor or something very well may be worth listening to (I have a very specific, very talented/prolific mastering engineer in mind...I actually respect him a lot, just not when it comes to gear).

It's literally the exact same effect that means you can't use Cat5e cables for 10GbE connections except for very short cable runs....except that LPF has a cutoff in the GHz range (IIRC). Electronically, it's the exact same thing except you plug different numbers into the formula.