Mono In Stereo Out Bypass Switch - Do I need a buffer?

[facon]

I'm trying to figure out how to approach a bypass switch for a mono in, stereo out pedal. After this pedal, I use a stereo signal for the rest of my pedalboard. I'm wondering, since the input signal is mono, when I bypass the signal, it will remain in mono. So, should I just put a buffer in line, then split the signal into dual mono? Or since I have a buffer at the beginning of my pedalboard chain, and a buffered stereo pedal at the end, should I be fine by simply splitting the signal passively by just running the same output wire to both output jacks? I already have transformer isolation at the end of my signal chain.

I'm trying to avoid signal loss by passive splitting and harshness by having too many buffers that are always on in my chain (if that is even a problem anymore with good buffers).

[slacker]

If you've already got a buffer in line there should be no problem just splitting it passively like you suggest. I would probably add a buffer to the pedal in case you ever want to use it without a buffer before it but I don't mind having "too many" buffers

[blackieNYC]

+1
I just looked into this, and got some good advice here in the forum.  A buffer is sufficient for most splitting purposes, and your mono chain may provide sufficient buffering. Splitters involving two parallel amplifiers are not often needed.  If you have a nice high impedance on the input of each stereo path, like 1M, you'll have a total Z of 500k, and if your preceding active circuit has a low output impedance you should be fine.  If you always have something active at the head of the line, you should be able to split.  I did, with no measurable or observable sonic loss.  If a FUzz face like device might be first in the stereo paths you may have a problem.   But they like to be after the pickup anyway, and should be further upstream.
So, with most designs you'll find here, that active device upstream should be sufficient as a buffer to precede the passive split. Listen, make sure nothing in the stereo chains, selected one by one, will cause signal impairment.  Try each one of your preceding pedals in the mono chain, and make sure any pedal there is capable of driving the split.  and if you have oscillator app I and a voltmeter, you can make measurements and look for loss that way. If you need that kind of satisfaction.

[facon]

Thanks for the advice! I'm going to build it passive and if I notice any signal loss, I'll throw a buffer with a toggle switch on it. I think I may have an extra populated cornish buffer pcb laying around somewhere.

Fuzzes are definitely at the very beginning of my chain before the buffer.

I'm always fearful of going back to the old days when I had a ton of boss pedals in a row and my dry signal did not sound very good at all. I'm sure it's overly cautious, but I just love my guitar tone as it is right now. If I'm noticing anything "off", I have oscillators, a signal generator, oscilloscope and a DMM that i could use to track it down.