CraigGT

Fair enough :-)

I must be missing something, why is it any different from a normal amp with an FX loop between the pre and power amps?

Can't you just treat it as a standard 4cm method but use preamp out/ power amp in instead of FX loop send/return.

If you don't need all the ins and outs then the LT might be a better option.

You can set up a loop as you want it, rename it and save it as a favourite. Then it's easy to drop it into all your presets, but only one at a time as @phil_m said.

Oh I've played there a few times! I'm about halfway between there and the “World Famous Theatre Club”

I was never a football fan so I wasn't any good so I always the goalie but yes it was the Billy Bremner, Peter Lorimer, Eddie Grey era.

It happens because the rotary encoder is pivoted and moves above the switches so eventually a wire breaks. It's definitely not a software issue.

I fixed mine myself but it took a few hours to do so £100 isn't really that bad. PS, I grew up in earshot of Elland Road in the Billy Bremner era!

That is all irrelevant, differing Impedances only affect frequency response when the source is inductive which none of these are.

Yes from the schematic, I've not measured the 1/4" outs but you can be sure that they'll be low enough to not be of any concern.

The send is around 22K and the return is 47K, the front jack could be anywhere between 2.5M and 0 depending on what frequency you test it with.

Feel free to test them but I haven't really changed my facts, I said that Helix Returns are 1M but didn't realise at the time that they changed to 10K when set to Line. I never said they were 2K, that's for Sends. I already know what they are for your amp, We can compare results later :-) Of course I understand - carry on :-) Ps maybe they're not facts but they are actually little resistors with 1% tolerance :-)

Why would you need to get a pot and do the tests? We've given you the facts, it's science, it's not debateable.

Then do it one step at a time starting with an empty patch. Guitar -> Helix guitar in Helix Send 1 (set to Instrument) -> Guitar amp in With nothing in the amp effect loop it should sound the same as plugging the guitar in the amp (make sue Helix Pad is off) Then Amp FX Send -> Helix Return 1 Helix Main Out -> Amp FX Return The sound should still not change however overall level will be dependant on the Helix main Volume knob. I've attached a preset When it's all working, before amp effects go on the top line Effect loop effects going on the bottom. 4CM Start.hlx

I'm kind of lost with what you're trying to achieve now.

But you're not dealing with a guitar signal on the loop send of your amp, it's a robust amplified signal that should be largely indifferent to minor impedance mismatches. Have you tried just plugging a cable between the send and return of your amp? it's not unknown for the jacks to be faulty?

Yes.

I just measured the send and it's 2K

No you've got that the wrong way around, it's a low impedance source feeding an high impedance input which is correct. The effect of feeding into a lower impedance would be less level and possibly some loss of high end. This would be more pronounced with a straight guitar signal which is why some of the old fuzz's have a lower input impedance. PS I made an error earlier, The Helix Returns are 1M on instrument and 10K on Line

Damn you're good with the quotes :-) The fundamental issue here is that audio systems don't use matched impedances, matched impedance systems are used for higher power/higher frequency systems when power efficiency/lack of reflections are desirable. (maximum power transfer) Audio systems use a lower impedance source feeding higher impedance inputs, eg my Strat measures less than 6k but that feeds into a 1M tube amp input. (maximum voltage transfer) I've also remembered that when I used a normal Helix patch into my amp effects return it was far too loud on line so I used instrument level instead, yes my amp maybe a "nominal" -6dbV out (somewhere between line and instrument) but what is nominal? with the gain and boost flat out with a Les Paul or with lower setting and a Strat? that's a much bigger difference than the difference between line and instrument level definitions. Your understanding of a preamp (amplifying voltage) is correct but in the case of the Roadhouse, there are four stages of amplification before the loop but there is also the tone stack which reduces the signal level considerably. The point about the compressor is that you would set it up to work how you like it at a certain input level and changing any gain settings on your amp affects that operating point considerably. if you put it between the guitar and amp it would behave more consistently. Of course that's thinking technically, if you like how it sounds then it's good.

No they don't, they're 1Meg there is no need for them to be anything else

I just looked at a schematic for your amp and the effect send is after the Vol (Gain) and the switchable Lead Master Vol but before the Master Vol . That means that the send level is completely dependent on the settings of those amp controls. It's probably line level when they're on 10 but somewhat less at other times. If you put a compressor in there it's going to be unpredictable because there are too many variables before it. That's why PierM said what he did.

As I said, my Helix is set up for Instrument so a line level signal would be too high. So knowing that it's sending at instrument level it follows that I need to send the same back to it. It's a Cornford Roadhouse. I do think you're overthinking this, Set up an empty patch, set the relevant ins and outs to Instrument, play a note and unplug the cables from the amp and nothing should change. Do the same with Line levels, decide which is best and stick with it. Some amps have the Master Volume before the Effect Send which makes it all irrelevant anyway.

Because using it like that gives unity gain through the Helix. If the amp was sending a line level then it would overdrive the Helix If the Helix was sending line level it would overdrive my amp. Like PierM says, you don't really want to changing gain in the loop.