HarryN

Just so happens I solved the hum issue with my Laney Ironheart today and was browsing this forum for the first time in ages. So this coincidences allow me to reply to your question about solving hum from the Laney amp - assuming it is ground loop hum. I've been having this problem with the Laney for ages and never quite managed to solve it. Quite a while ago I bought a Behringer HD400 passive hum destroyer (very inexpensive) but never got it to work. I realise now I was using it wrong - trying to connect both the send and return of my amp to it. Here's what I did today. I just connected the HD400 to the line that was going from the POD HD to the amp's FX return (so just using one input and output on the HD400). Thus breaking the physical connection (but not signal connection) between the pre-amp and power amp. And the hum was gone. Can't believe it's taken so long to do this. And thus I've been enjoying an almost silent 4CM with my POD HD500 and Ironheart this evening. Tonight I even experimented with the 4CM method that doesn't use the POD's FX loop at all. Guitar > Pod Guitar Input > POD Signal path B > Guitar amp input > Amp FX send > POD Aux Input > POD Signal Path A > Amp FX Return. Can't believe I've never tried it before, works a treat. The only downside is you can't use the looper. Interesting discussion on routing this. It took me a long time to figure out the signal routing on the HD500 myself and I bought one the week of release. It was finally realising that both the A and B paths were separate stereo that made everything fall into place. I tend to build patches totally in one signal path now - it's my preferred method. I keep A and B completely separate. I almost never put pre-effects before the split, always fully in the side paths before the amp, then after the amp.

The problem with that is you send a very hot signal into your effects. Which is fine if your effects can cope with it. But some will sound not so good.

My guess the return attenuation was put in place to hide the horribly noisy effects loop circuitry. I can't think of another reason why L6 would do it. I did spend a lot of time measuring sound levels through the loop and worked out a blank patch I could use for the 4CM that didn't lose me signal. But in the end I got fed up with trying to make up for the POD HD issues through the loop. So now I don't use the FX loop at all - not for effects, not for 4CM. If I want to use the unit with a real amp I plug it into the effects return of the amp to just use its power stage. I don't lose blocks and I don't have to play with the screwy signal path in the POD. Sounds very good this way. Obviously you lose your real pre-amp, but I find it less annoying than trying to balance levels through the poor quality loop on the POD.

Good post. The unholy mess that is POD HD signal routing drove me potty for the first year of owning the thing. I gradually worked out how best to use it - for me. As I never bother with dual-amp patches I put all effects and amps in the A path and mute the B path from the mixer. The mixer stays at the end of the chain with all effects before it. As your routing guide shows this is a much more consistent approach. L6 made quite a mess of the signal routing in POD HD and back when the company could be bothered to post on the forums gave the impression it didn't understand what was happening. Which implies the signal routing wasn't exactly planned this way.