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Paolosev91

4cm Method Improved! Less Latency, Less Noise

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4CM Low-Latency Low-Noise solution: (previously posted by me on another forum, may be useful for many pod users out there)

I found out that the pod's fx loop send introduces more noise and more latency compared to the normal line out of the pod.
So I found out a way to reduce both noise and latency introduced by the pod's fx loop when using 4CM, if you don't care about hitting your amp's fx loop with a stereo signal.

The basic idea is: pre-amp signal on Right channel (Path B) (with wah, compression, distortion effects) / post-amp signal (with reverb, delay effects) on LEFT channel (Path A). (Do not switch Path A and Path B, otherwise you will get more latency, since the pod processes path B before path A).

 

Now: 
1) Set input 1: Variax, input 2: Guitar (using same, this method doesn't work at all, we need discrete signals)
2) Don't put any effect in pre-path.
3) Put every pre-effect (wah,comp,dist..) on PATH B (lower), and pan the mixer full to the right.
4) Put an FX loop block (be careful, it must be TURNED OFF! It works, and doesn't add noise and latency as when it's turned on!) and after it, every post/loop-effect (delay, reverb..) on PATH A (higher), and pan the mixer full to the left.
(If you turn on your FX loop block, you will hear more latency! But now you don't need it. That's the first reason why this solution is better than the standard 4CM routing)
5) Cable routing: 
- Guitar cable in pod's guitar in input
- Run a cable from pod's Right line output to your amp's guitar input.
- Another cable from your amp's fx loop Send to your pod's fx loop Return.
- Last cable from the pod's Left line output to your amp's fx loop Return.
6) To have overall unity gain and less noise as possible, I use:
- Pod's master volume to 100% so my guitar sounds like it's directly plugged into my amp
- Guitar In switch set to normal
- 1/4" Out switch set to amp
- Fx loop switch set to Stomp if you want less noise possible and attenuate your amp (I get wonderful sounds at low volume with this on!!!). Set it to Line if you want to have the same volume as the pod was not in the amp's fx loop, but you will have a little more noise.
- Mixer settings at +4db for my pre/right signal and 0db for my post/left signal.

This is the same as the "normal" 4CM method, but splitted in 2 separate signals (Up=before preamp, Down= after preamp) and gives you the best SNR and the shortest latency you can get out of the pod!

The same patch can be used, disconnecting both send and return cables from the amp's fx loop, to have the best signal from the pod when using it just in front of the amp.

To use pod's pre and full amp models with the configuration shown before, just set up a patch with input1: guitar, input2: same and an amp block in pre-path position, then pan one of the amp's paths (they're both full stereo paths!) to the left so you will send it to your power amp, remembering that path B gives you less latency also in this case and adjust mixer gain as desired. So the best way to set up a pod model patch when using my 4cm cable routing is: amp pre-path->path A muted, path B fully panned to the left.

 

There's only one little drawback: if you set input1 as I do, you will not be able to use the tuner. What I do is create another patch or tune my guitar with my amp model patches (in which I use input1:guitar, input2: same). Use input settings:"preset" to achieve this.

 

Hope this helps.

Paolosev91

 

Feel free to copy this method on other forums and threads! Since Line6 built a great pedalboard, but with a quiet cheap fx loop, I think that a lot of users will benefit from this.

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Okay, kinda makes sense The idea is to utilize the two paths One for pre and one for post

Without actually measuring with some loopback analysts software my first thought is  I think that whatever the latency is , it is negligible. If there is an additional latency difference it won't be a perceivable one. That is my first thought. A pessimistic one .

 

I am not saying that this isn't less and you know I totally beeive that with some time based FX and some DSP expensive FX the time it takes to process in the HD would be a factor probably no less than using real hardware FX.

 

When I get a chance to try it I will.

But can you hear a difference in the latency.?

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I still haven't tried this, but it has me curious and asking a few questions.

How do you know path B is processed before path A?

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I think it's absolutely ridiculous that we have to do this just to get a 4CM that doesn't suck tone or volume in some way or another.  

 

I still use my POD HD 500 for practicing but I gave up on using it with my amp.  Even the convenience of the Midi channel switching wasn't enough.  I use a pedal board that limits my effects use but I'm much happier with the sound and not having to trouble shoot everytime something goes wrong.  There are several switches on the POD that if even one is turned to the wrong way it will seriously screw up your tone.

 

I've said it before and I will again.  When Line 6 tried to make the POD HD series work for everyone they made it too complicated.  They also didn't prepare for the ways some people would want to use the product.  That's OK normally, it's not for everyone, but they promote the product like it works great for everyone and in some ways that it "should" work, like as a stomp box modeler before your amp or the 4CM it falls very short.

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I did something like that with my HD Desktop to 4CM the POD into an amp since the Desktop doesn't have an FX-loop....It's called Serializing the Chains...The problem I had with this approach is that the Master doesn't have discrete control of the Left and Right 1/4 Analog Ouput Level...While it is possible to find a setting that works and use the mixer levels to tidy up, I found it to be a tempermental setup...If the master was a concentric pot, it would work a lot better I think...

 

here is the original thread....I think there is a patch there too...

 

http://line6.com/support/topic/2177-4-cm-the-hd-pod-bean-oh-yes-this-works/

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What makes you think path B gets processed before path A? It seems to me that you're not really avoiding latency, just moving it around.

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There's one thing that you can hear more than latency, which is noise.

Follow my guide (be careful with details on pod switches, levels and cable routing) using e.g. the distortion channel of your amplifier and compare it with the "standard" 4CM method... you will hear less noise.

 

Latency is something I became aware of when I used to play with the pod and then (finally!) bought a real tube amp. Plugging the guitar directly in my amp gives my almost "0" latency which is fantastic since it makes you play more naturally and there's a unique feel because of that "direct" sound, I was never able to achieve with the pod models.

 

Speaking about Path A and Path B latency I am 99% sure about the fact Path B is processed before because:

- I hear less latency when I mute path A and more if I mute Path B.

- If you follow my method and switch Path A with Path B (then you will have to "cross" the mixer panning, so you don't have to change your cable routing!)

I have 2 patches on my pod, one like my guide says, and another one with pre-effects on path A and post-effects on path B, path A panned right and path B panned left.

Switching between the two patches I hear less latency with pre-effects on path B, so I suggest you to use that. To me it was a clear evidence that path A is processed after path B.

The reason may be that the pod is able of computing a stereo signal (2 mono signals in parallel), but it is not able of computing two stereo singals (the two paths) in parallel!

So, feeding path B "before" path A, gives you less latency because, otherwise, it takes the Pod two "cycles" to process your signal!

 

Why is my 4CM method better than the "standard" one?

The most important difference is that we are not using the pod's fx loop output, which is very noisy and adds a really noticeable latency (definitely more than the difference between the pathA/B thing.)

 

 

I did lots and lots of presets, cable routing and it took me a lot of time but the guide I wrote in this post is, to me, the lowest noise, lowest latency mode you can get out from your pod. Try it ;-)

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it would be cool if there was a way to ask the guys (or one of them, or someone who knows how to find out) who made the device what the scientific specs are.....

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Both paths A + B are stereo.

 

Check out foll link:

http://line6.com/support/topic/2033-pod-hd-500-500x-new-routing-schematics/

they are both separate stereo signals right up to the mixer.  From that point on it is just one stereo signal out.  That is why the mixer allows us to blend the two stereo signals which ever way we choose.  I am not sure if the original poster was referring to being able to output two separate stereo signals but that is definitely not supported by either the hardware or the software.

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UPDATE:

 

my thought on Path B may be partially wrong.

Switching between my 2 patches I felt I had more delay when I had pre-effects in Path A and post in Path B and less delay when viceversa.

So I thought that the pod processes Path B before Path A!

 

Now I decided to try a different configuration (even less latency!!!).

Instead of using the fx loop return of the pod, I am using its Aux in.

Seems strange, but except from a 4db loss (easily corrected adding +4db at the mixer), it has more or less the same noise, but less latency!

Then I built my 2 patches, 1) input1:guitar input2:aux with pre-effects in Path A and post in Path B, 2) vice-versa.

And also now the tuner works!

 

What did I discover? I have even less latency then when using pod's fx loop return, and solution 1) gives me even  less latency then solution 2)

 

Try it, you may be surprised of how responsive will be your pod in 4cm mode now!

 

My thought (I am not 100% sure about that, just wondering...) is that the pod was programmed to process the signals I am using in this sequence:

Path A -> Path B -> Fx loop return signal. (seems like line6 programmed the pod giving less priority to the fx loop signal)

 

If true, this may confirm why when I am using fx loop return on Path A I have less latency than using it in Path B!

The pod did Path A -> Path B -> Fx loop return -> Path A  (4 "steps") ,

instead of Path A-> Path B -> Fx loop -> Path A -> Path B  (5 "steps").

 

And it may also confirm why I am getting less latency using no Fx loop, and even less when using pre-effects on Path A.

pre-effects in B, post in A: pod does Path B->Path A-> Path B (3 "steps")

pre-effects in A, post in B: pod does Path A->Path B (2 "steps").

 

My thoughts on WHY this happens may be wrong, but however, please try it:

Guitar -> Guitar in -> path A panned left -> left output -> amp front -> pod aux in -> path B panned right -> right output -> amp return (mixer volumes both at 4db, pod's master at full, output switch on Line.)

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I created this patch for using 4 cable method with my Variax without using the POD FX loop.  Works great!  Gives you all 8 FX blocks to use for anything you want.

 

Variax-->POD-->Right Out-->Amp Guitar In-->Amp FX Out-->POD Aux In-->Left Out-->Amp FX In.  

 

Set POD out to Line, POD Master up full.  Adjust Mixer to set correct levels for preamp and power amp inputs.

 

http://line6.com/customtone/tone/274440/

 

** Customtone sometimes changes input settings - be sure input 1 is Aux and input 2 is Variax **

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I don't know about the latency but I just wanted a method that didn't involve the POD FX loop.  Frees up a block and I don't have to worry about signal drops or the extra noise...

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Following up on my previous work with 4CM without using the POD FX loop,  I really like this method.  I get to use all my FX blocks and there are no noise issues or signal drops as with the FX loop.

 

This link is for using your amp's pre section: http://line6.com/customtone/tone/274440/

(put pre FX in channel B, post FX in channel A)

 

This link is for using the POD internal amps: http://line6.com/customtone/tone/277915/

(put everything in channel A only, channel B is muted)

 

- I made this for Variax but if you change Variax to Guitar it should work just fine.

- You will have to play with the mixer levels to balance with your particular amp!

- Be sure input is set to Preset not Global!

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radatats   does this set up act like an effects loop???  what I mean is can I put dist-comp-eq before preamp and mod after preamp?  Im about to sell this pod because of the noise of the effects loop. I finally have an amp that I can use the pod in a 4 cable setup but im really pissed that they couldn't make it with with less noise.

 

Thanks

 

M

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Yes! Absolutely...

 

4CM-4 - put all your dist-comp-eq in channel B (the bottom path), that signal goes out the Right jack to the amp guitar in.  The amp FX Send comes back in the POD at the Aux jack and feeds channel A (the top path).  Put all your mods-delays-reverbs up there and that signal goes out the Left jack to the amp's FX Return and feeds the power section.

 

4CM-5 - acts like a regular POD patch except EVERYTHING stay on channel A (the top path).  put all your dist-comp-eq first before the amp block (you can choose a pre model or a full model whatever sounds best) and all your mods-delays-reverbs after the amp block. NOTHING goes in the bottom path and the mixer stays muted for channel B.  The whole signal goes out the Left jack straight to the amp's FX Return and feeds the power section.

 

Start with the POD master at 1/2 or less and your amp Master or volume low.  You will need to play around with the mixer levels/Master levels until you get the right combination to feed your amp without totally overdriving it.  The POD Master controls the signal level to BOTH the amp's pre and power sections but you can fine tune it with the mixer levels.  Try to get your levels similar to where they are with just pluggin in a guitar.  Does that make sense?

 

Anyways, once you have it set, save it as a new patch and use it as a template for your future creations.  Now to change from amp pre to POD pre you will have to change patches instead of turning the FX block on and off.  No big deal especially since the FX block is a pain in the butt anyways...

 

Hope that helps, let me know how it works for you!

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This is a very creative solution! I like it. We may complain a lot about its various failings but this just shows how flexible the HD500 is.

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I haven't had a chance to try it yet but if it works as advertised, then VERY COOL!! Thanks radatats  Ill let you know how it works for me.

 

M.

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Well I hope I'm doing something wrong because this isn't working for me. amp cranked to 8 - pod cranked to nearly full I get very little sound. ... double checked cabling im good there. checked settings and switches good there. I disconnected the amp fx send and return and now I have good sound levels. However a lot of noise with the amp turned to 0. anyone wanna buy a pod hd500?? I guess im going back to pedals. Dammit!!  I hoped this was going to work. Thanks for your help radatat.

 

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Is that with 4CM-4 or 4CM-5?  I don't know why it shouldn't work for you if it works for me...  let me know if you want to try to work it out...

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tried it out this afternoon, works great,

but i didn't noticed any difference to the normal 4cm, switched between the two 4cm's 5/6 times, not any noise and latency difference that my ears could hear( didn,t noticed any latency with the normal 4cm in the first place)

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tried it out this afternoon, works great,

but i didn't noticed any difference to the normal 4cm, switched between the two 4cm's 5/6 times, not any noise and latency difference that my ears could hear( didn,t noticed any latency with the normal 4cm in the first place)

I'm pretty sure its an audio mirage.....engineers do this to people in the studio all the time. adjust something that has no effect and all of the sudden it sounds a lot better!

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Maybe? I just a/b 'd guitar straight vs hd500x 4cm 5 times didn't noticed any latency, nothing my ears could detect.

I,m very happy with the hd in my rig.

Maybe it has someting to do with some amp effect loops, mine is tube driven.

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tried it out this afternoon, works great, but i didn't noticed any difference to the normal 4cm, switched between the two 4cm's 5/6 times, not any noise and latency difference that my ears could hear(didn,t noticed any latency with the normal 4cm in the first place)

 

Yeah, the OP talked about latency but I never found any either.  I just liked the fact that it freed up a block by not using the FX loop and the associated noise and signal level issues.  Glad it works, mput had me worried maybe I explained it wrong...

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