pedal output and "line level" output - difference in output impedance

[lcipher3]

I think I posted some of this before - but I'm still confused about "output" stages in pedals. I assume most pedals are "designed" to work with guitar inputs on amps. So the amp typically has a high impedance 1meg etc right? But if you want to plug a pedal into a "line level" (either +4dBu or -10dbU) the line level is typically lower input impedance.

So I would think a typical pedals' output stage would be "off" when driving a line input. Then there's the whole isueof either -10dBU (~0.25V) vs +4dBU (1.228V).
I've searched extensively (maybe because its a stupid question) but cannot find anything on what you would do design wise for a pedal that you want specifically to go into a LINE level input.

Yes - I know that pedal effects w/o cab and speaker effects can sound lame. Just looking for a JFET front for input to a line level. For example: - the episode boots. What would/should the output stage look like ? Probably adjust gains and R9,R10,R11?

 

[Feral Feline]

There's the Klein-ulator and other similar circuits that convert instrument to line-level and vice-versa; if you want a pedal that's going to have its output a dedicated line-level, I'd start with reading up on the Klein-ulator and similar.
Effects-Layouts has something along those lines, and commercial-grade there's something from Radial Engineering (home of the Tone-Bone pedal-series and touring solutions).

 

[giovanni]

AFAIU, the main difference between instrument and line level is volume, with line level being way louder. The impedance issue is related but separate. Since guitars produce a very small signal they need a really high input impedance preamp so that the pickups don’t get loaded, i.e., so that the tone is not dull. Line level signals are typically already preamplified and the device that does the preamplification has a very low output impedance, which means that the next stage can have a lower input impedance. That doesn’t mean it has to. So if you want to design a device that works with both instrument and line signals, the main thing you need to worry about is its ability to handle a much larger signal. I suspect that this is done by having a switchable preamp that can bring a guitar level signal up to line level. As far as impedance goes, the device should have high input impedance so it can handle a guitar and low output impedance so it can drive a stage designed for line level devices. High and low impedance are all relative concepts. You always want high input/low output impedance, but the typical ranges for guitar vs line level signals are much different. So if you overcompensate in both direction, you are good to go.