Drive pedals in low impedance modeller loops

[metropolis_4]

I get the fixed positioning rationale. The signal chain methodology and management is dumb overall though. Unless they overhauled it since I had it? You awkwardly grab a signal chain type on the side and it blows up the whole thing you have built. You couldn't control the levels of external loops via expression pedal last I knew which I could do on the Kemper a decade+ ago. It's a touchscreen and I actually like the skuemorphoic thing but it still felt like using something from 2014 as far as getting around on it went.

Oh it definitely deserves flack for its signal chain routing, I just don’t feel like it deserves it for those two analog loops. I thought those were a great idea

 

[JiveTurkey]

Oh it definitely deserves flack for its signal chain routing, I just don’t feel like it deserves it for those two analog loops. I thought those were a great idea

For me; I am so pulled back into regular pedalboard mode I wouldn't use those loops anyway as I am tapdancing like a madman and liking it!

 

[metropolis_4]

For me; I am so pulled back into regular pedalboard mode I wouldn't use those loops anyway as I am tapdancing like a madman and liking it!

Me too, and I love it! I have had a couple times though when I’ve thought about trying a loop switcher to have all my drive pedals in one loop and comp->EQ->SCF in the other loop so I can toggle between clean/drive and turn on/off multiple drives at once.

I’ve thought the TMP might be a good option for that. Use the two analog loops for clean/dirt pedal chains and just use the device as an amp/loop-switcher

I’m an all-pedals-up-front guy so that would work for me

 

[DieSchmalle]

[...] It has a 50k output impedance so, in theory, everything downstream in the loop should be more protected from the low impedance send from the modeller.

What does this even mean?

 

[MBT74]

What does this even mean?

By that I mean that the pedals after the buffer aren’t seeing 1k from the send jack of the Core’s loop anymore. They’re seeing the output of the always on buffer which is 50k.

 

[synthpenguin]

Me too, and I love it! I have had a couple times though when I’ve thought about trying a loop switcher to have all my drive pedals in one loop and comp->EQ->SCF in the other loop so I can toggle between clean/drive and turn on/off multiple drives at once.

I’ve thought the TMP might be a good option for that. Use the two analog loops for clean/dirt pedal chains and just use the device as an amp/loop-switcher

I’m an all-pedals-up-front guy so that would work for me

Yeah, I have a compressor that I only use for cleans and a drive pedal I only use as a lead boost. It would be great to be able to control that within a modeler patch without having to get a MIDI loop switcher.

It won’t work for every situation since it’s at a fixed point in the chain, but it seems nice for things like that or for fuzzes.

 

[EOengineer]

I wasn't aware of that loop feature in the TMP - pretty cool.

 

[Sascha Franck]

Isn’t the whole purpose of those loops that they don’t involve any AD/DA conversions?

Sure. That's why I wrote:

Would be tremendous if the send of the digital loop could be placed in front of the analog loops and could be taken out with the help of some relais switch

That way, you could have it both. It'd be like adding another loop in front of the analog ones, just that it'd be routed internally and could as well carry digital FX. In case you don't need it, everything would be fully analog and unbuffered.

 

[DieSchmalle]

By that I mean that the pedals after the buffer aren’t seeing 1k from the send jack of the Core’s loop anymore. They’re seeing the output of the always on buffer which is 50k.

Pedal inputs seeing output impedances of previous devices? What does that even mean?
#SocraticMethod

 

[Sascha Franck]

Pedal inputs seeing output impedances of previous devices? What does that even mean?
#SocraticMethod

Pretty much the same as other impedance mismatches. Think headphones and such.

 

[Chocol8]

Pedal inputs seeing output impedances of previous devices? What does that even mean?
#SocraticMethod

Over simplification warning: The ratio of the output impedance of one device to the input impedance of the next can have a meaningful impact on the performance of both.

If you think of current like water in a hose, the size of the hose and internal friction would be impedance. A small hose (high impedance) flowing into a larger one (low impedance) is going to behave quite differently than a big hose trying to flow into a little one.

 

[DieSchmalle]

Pretty much the same as other impedance mismatches. Think headphones and such.

So it's about impedance mismatch.

The impedance of headphones isn't fixed value, but a curve with very pronouced resonance and and an impedance increase in the highs due to the voice coil. A typical drive pedal's impedance is very constant - so that's isn't a fair comparison.

A mismatch isn't a problem if the output's, the input's and the signal transmission path's impedance are more or less constant in the audible frequency range.

 

[DieSchmalle]

Over simplification warning: The ratio of the output impedance of one device to the input impedance of the next can have a meaningful impact on the performance of both.

If you think of current like water in a hose, the size of the hose and internal friction would be impedance. A small hose (high impedance) flowing into a larger one (low impedance) is going to behave quite differently than a big hose trying to flow into a little one.

Please explain professionally using technical terms. Disect the electrical circuit from output to input and include impedance curves and parasitic effects. A comparison between a 10:1 (regarded as ideal) vs 1000:1 (Boss send -> typical 1 MOhm pedal) impedance mismatch ratio would be appreciated.

 

[unix-guy]

Isn’t the whole purpose of those loops that they don’t involve any AD/DA conversions?

Forgive my ignorance because I know nothing about the TMP...

But how is it possible to interface analog devices into a digital signal path without A/D and D/A conversion?

 

[Sascha Franck]

A mismatch isn't a problem if the output's, the input's and the signal transmission path's impedance are more or less constant in the audible frequency range.

I can't come along with any technical explanations, but the effect is still there and there's pretty much no other explanations for it, especially as it can't be adresses inserting a little circuit such as the ones mentioned here, doing nothing else but changing impedances.

 

[Chocol8]

Please explain professionally using technical terms. Disect the electrical circuit from output to input and include impedance curves and parasitic effects. A comparison between a 10:1 (regarded as ideal) vs 1000:1 (Boss send -> typical 1 MOhm pedal) impedance mismatch ratio would be appreciated.

Please pay tuition first. Also, we aren’t talking about Boss and “typical” 1 Mohm input pedals.

 

[metropolis_4]

Forgive my ignorance because I know nothing about the TMP...

But how is it possible to interface analog devices into a digital signal path without A/D and D/A conversion?

My understanding is that they’re placed after the input and before the first D/A conversion. So they happen before the signal ever converts to digital

 

[Sascha Franck]

My understanding is that they’re placed after the input and before the first D/A conversion. So they happen before the signal ever converts to digital

This. And it's a great idea that some other companies could adapt IMO. No impedance issues, no possible signal quality alteration/loss due to ADDA conversion and op amps, no additional latency. Should even be pretty trivial and add little extra cost. I mean, there's loop switchers costing very little, I'd say most of their cost comes from anything else than the extra I/O sockets and relais.
As said, could be expanded by allowing you to slap a part of the digital processing in front if needed (which then should of course offer analog true bypass).

 

[unix-guy]

My understanding is that they’re placed after the input and before the first D/A conversion. So they happen before the signal ever converts to digital

That makes sense and now makes sense as to why they can't be placed as desired in the signal path.

 

[djd100]

I asked something similar to this when looking for a buffer compatible fuzz.
Apparently things can at least partially be solved by a little DIY thing. I got that as an answer in that thread:

Guitar Pickups Simulation

Schematics & circuits for guitar effects with vacuum tubes and solid state electronics. FREE downloads of schematics such as TS-9, Fuzz Face and other classic rock devices.

www.muzique.com

Haven't tried myself yet.

I built something similar to this to run analog pedals in front of a ToneX One or various tube preamps in my FM3's FX Loop, works well.