effect placement Pros and cons for effects in between amp-block and cab

[Smashcraaft]

Hello. After switching from the POD HD500x I am building my presets from scratch on the Helix and I am unsure if I should keep some free space for effect in between amp-block and cab or use the Amp+Cab cominations.

Which effect should be definitely placed in between amp-block and cab?

I like to try some recommandations before and after the cab for a comparison in the results.

[rd2rk]

The unhelpful answer is "whatever sounds best - no rules here in the digital wonderland!"

 

If "feel" is important to you, it's my understanding that the speaker impedance curve is baked into the amp and specifically matched to the cab that L6 uses in the full amp+cab block. As long as you use that cab, there's no other reason to care about separating the amp and cab.

I couldn't tell you if having the matching speaker impedance curve really makes a difference, I don't notice it and have always used whatever cab/IR sounds best.

 

EDIT: placing time-based FX in an FX Loop (between pre and power amps) is not the same as placing them between the power amp and speaker (as in Helix).

 

Generally, I put the cab/IR at the end of the path that goes to FOH (XLR) and nothing between the split and the 1/4" out to my stage amp's Return, (currently my Catalyst which is in 4cm).

 

Think of it this way - much great music was made before FX Loops, with ALL FX between the guitar and amp input.

In the studio, most engineers take a DI to the board and add FX in post. I can't tell the difference, can you?

 

[theElevators]

You can achieve interesting sounds by breaking the rules.  For example, everybody says add reverb at the end of your chain.  Prince did the opposite -- he added reverb before gain.  End-result interesting / unusual chaotic sound.  https://youtu.be/00199ZXKZK8

 

Typically nobody adds effects between the amp and the cab, but nobody is stopping you.  You can also run a cab into an amp.  You may achieve interesting colors...

 

A guitar processor allows you to achieve studio-quality sound for live use.  Studio-recorded guitars usually are recorded dry; then stereo delay/reverb are added in post-production.  So if you add effects after amp/cab, that's what you will be mimicking. 

 

Anyway, no pros/cons I can think of, except like @rd2rk said, so what sounds best.  For example I was searching for that springy spongy 60's surf sound... and no matter what I did I couldn't get it.  Until I tried an envelope filter as the secret sauce in addition to the usual '63 reverb or "hot springs" and an amp..  All of a sudden the sound I was hearing in my head was achieved. 

 

Another example everybody looks at me like I'm mad when I say I boost my solos with an EQ block where I boost 2K 10 db -- they think it's too much, it's incorrect, it's this and that.  Well, it works for me and it makes my solos pop. 

[Smashcraaft]

So no need to split Amp+Cab for a more or less traditional usage of chains, right?

I like the idea to dial in my preferred combinations of A+C perfectly and store these as defaults.

[Smashcraaft]

On 5/30/2023 at 9:50 PM, rd2rk said:

If "feel" is important to you, it's my understanding that the speaker impedance curve is baked into the amp and specifically matched to the cab that L6 uses in the full amp+cab block. As long as you use that cab, there's no other reason to care about separating the amp and cab.

I couldn't tell you if having the matching speaker impedance curve really makes a difference, I don't notice it and have always used whatever cab/IR sounds best.

 

Is this based on an official announcement of L6?

[Schmalle]

On 5/30/2023 at 11:20 PM, Smashcraaft said:

 

Is this based on an official announcement of L6?

This is no speculation. The amp models replicate the speaker out signal of an amp. It matters what load / cab is connected when modeling. How much depends on how much current feedback the amp has.

The impedance curve is an electrical frequency response of a speaker and it is indeed imprinted in the model. IRs on the other hand only contain an acoustic frequency response.

[rd2rk]

On 5/30/2023 at 3:20 PM, Smashcraaft said:

 

Is this based on an official announcement of L6?

 

I do not recall where I read it, which is why I specified "it is my understanding".

I THINK this was discussed in a major thread about impedance curves that ran on TGP in the D&M forum a couple of years back.

 

On 5/30/2023 at 3:17 PM, Smashcraaft said:

So no need to split Amp+Cab for a more or less traditional usage of chains, right?

I like the idea to dial in my preferred combinations of A+C perfectly and store these as defaults.

 

Unless you prefer the way it sounds with FX between. A while back there was a fad where people were putting ODs between.

Made no sense and sounded like crap to me, but whatever floats yer boat!

[Smashcraaft]

So from my understanding the separation of cabs from the Amp is more or less about experimental options and for users, that need to split paths (f.e. to feed a real cab on stage). 

 

Cool, this offers me the possibility to keep my paths as simple and lean as possible + let me save my complete A+C favorites the easiest way :)

 

Thank you for your help and kindness!

[Smashcraaft]

So from my understanding the separation of cabs from the Amp is more or less about experimental options and for users, that need to split paths (f.e. to feed a real cab on stage). 

 

Cool, this offers me the possibility to keep my paths as simple and lean as possible + let me save my complete A+C favorites the easiest way :)

 

Thank you for your help and

 

Edit: Ouh... this might be something I should consider to take a look at tomorrow :/

 

 

 

[rd2rk]

Per the JNC vid - yep, other good reasons to separate them.

Keep it simple or get as complex as you want, Helix does it all!

 

Notice that he demo'd the "fad" I mentioned - putting an OD between.

Sounded like crap to me :-P!

[brue58ski]

On 5/30/2023 at 3:12 PM, Schmalle said:

This is no speculation. The amp models replicate the speaker out signal of an amp. It matters what load / cab is connected when modeling. How much depends on how much current feedback the amp has.

The impedance curve is an electrical frequency response of a speaker and it is indeed imprinted in the model. IRs on the other hand only contain an acoustic frequency response.

 

I don't know if this has been mentioned but the new cabs are now a bunch of IR's. An IR was created for every possible iteration of the mic placement and other parameters. So each time you change the mic parameters (and maybe a couple more) it's a new/different IR. That's also the main reason why the new cabs us less DSP.

[silverhead]

On 5/31/2023 at 7:41 AM, brue58ski said:

 

I don't know if this has been mentioned but the new cabs are now a bunch of IR's. An IR was created for every possible iteration of the mic placement and other parameters. So each time you change the mic parameters (and maybe a couple more) it's a new/different IR. That's also the main reason why the new cabs us less DSP.

Yes, true! Can you imagine the tediousness of the development?

“Here’s your job for the foreseeable future, mister/miss Line 6 developer. See that collection of cabs and mics over there? Use this IR creation tool to create an IR for every specific combination of cab, mic, and mic position (to a specific granularity) in two directions. And follow this IR file naming convention so that the Helix firmware can properly index and locate/load the IR file on demand. Oh, and here’s your isolation pay bonus. Pack a lunch.”

 

It would almost be worth building a robot that moves the mic position in the specified increments and issues the Create/Save IR FIle” command. Then manual intervention would only be required to periodically change the physical mic and cab. Makes me wonder if they actually did that.

[brue58ski]

On 5/31/2023 at 5:16 AM, silverhead said:

Yes, true! Can you imagine the tediousness of the development?

“Here’s your job for the foreseeable future, mister/miss Line 6 developer. See that collection of cabs and mics over there? Use this IR creation tool to create an IR for every specific combination of cab, mic, and mic position (to a specific granularity) in two directions. And follow this IR file naming convention so that the Helix firmware can properly index and locate/load the IR file on demand. Oh, and here’s your isolation pay bonus. Pack a lunch.”

 

It would almost be worth building a robot that moves the mic position in the specified increments and issues the Create/Save IR FIle” command. Then manual intervention would only be required to periodically change the physical mic and cab. Makes me wonder if they actually did that.

 

It would take awhile but, they said they did soooooo....I just believe them. I was kind of hoping they could come up with an "empty" cab and it could be filled with IR's by outside vendors. Or even by helix owners? That would be a lot of work. I think they use a robot to position the mic so that would help in how much time it took them to do this. And they didn't get to every cab either.

[silverhead]

On 5/31/2023 at 10:48 AM, brue58ski said:

 

It would take awhile but, they said they did soooooo....I just believe them. ….

 Yes, I do too. I wasn’t questioning you; just commenting on the size and scope of the undertaking.

[rd2rk]

On 5/31/2023 at 6:16 AM, silverhead said:

It would almost be worth building a robot that moves the mic position in the specified increments

 

IDK about L6, but IK has such a robot for that purpose. I can't imagine that L6 does it by hand. AARGH!!!

[silverhead]

Just for fun (?) I did the math. The new cab engine in firmware v3.5 introduced 20 guitar cabs and 4 bass cabs, and v3.6 introduced 9 new cabs. That's 33 cabs now running on the new engine based on individual IRs. The Release notes say:

 

"Thousands of impulses were captured with Sound Design's all new IR capture system"

 

Thousands? What an understatement if we take Line 6 at its word (and I do). I couldn't find detailed information on Sound Design's IR Capture system but unless there's some aggregation magic involved I presume each IR is captured separately and individually from the cab and mic sources. So how many is that?

 

In addition to the cab selection there are 4 mic-related parameters that I imagine are baked into an IR: Mic, Position, Distance, and Angle . I believe the other parameters Lo/Hi Cut, etc) would be applied to the IR rather than baked into it. By my understanding a unique IR is specified by the specific combination of values of all these parameters. What are the available discrete values? There are 12 mics; 101 Position values ranging from 0 to 10 in decimal point values; 45 Distance values ranging from 1.00 to 12.00 in 1/4" increments; and 2 angles, 0 deg and 45 deg. So for each cab there are 12*101*45*2 individual IRs. That's 109,080. With 33 cabs that's 3,599,640 individual IR files. I think it would be ludicrous to attempt that without automation, not only for the human effort involved but also because no humans could do that without introducing a large number of errors due to boredom and exhaustion.

 

So I bet there's an automated ratchet set of railroad-like tracks in Line 6 labs that moves a mic stand through 101*45 positions, with a 45 degree angling of the mic at each position.

 

Am I anal? Is it my CDO? (i prefer it in alphabetical order.) Whatever. Back to real life now....

 

 

[PaulTBaker]

Some time back people were swearing by putting  the kinky boost inbetween the amp and the cab.  They said it made a huge difference, in a good way.  A google search of that could tell you more.

 

I tried it and it wasn't necessary for what I was doing.

[Schmalle]

On 5/31/2023 at 1:41 PM, brue58ski said:

I don't know if this has been mentioned but the new cabs are now a bunch of IR's. An IR was created for every possible iteration of the mic placement and other parameters. So each time you change the mic parameters (and maybe a couple more) it's a new/different IR. That's also the main reason why the new cabs us less DSP.

True. And the reason why the new cabs and IR's use less "DSP" is because the IR convolution stuff is now computed with the DSP's hardware accelerator which works in parallel with the normal computation.

[Schmalle]

On 5/31/2023 at 6:15 PM, silverhead said:

Just for fun (?) I did the math. The new cab engine in firmware v3.5 introduced 20 guitar cabs and 4 bass cabs, and v3.6 introduced 9 new cabs. That's 33 cabs now running on the new engine based on individual IRs. The Release notes say:

 

"Thousands of impulses were captured with Sound Design's all new IR capture system"

 

Thousands? What an understatement if we take Line 6 at its word (and I do). I couldn't find detailed information on Sound Design's IR Capture system but unless there's some aggregation magic involved I presume each IR is captured separately and individually from the cab and mic sources. So how many is that?

 

In addition to the cab selection there are 4 mic-related parameters that I imagine are baked into an IR: Mic, Position, Distance, and Angle . I believe the other parameters Lo/Hi Cut, etc) would be applied to the IR rather than baked into it. By my understanding a unique IR is specified by the specific combination of values of all these parameters. What are the available discrete values? There are 12 mics; 101 Position values ranging from 0 to 10 in decimal point values; 45 Distance values ranging from 1.00 to 12.00 in 1/4" increments; and 2 angles, 0 deg and 45 deg. So for each cab there are 12*101*45*2 individual IRs. That's 109,080. With 33 cabs that's 3,599,640 individual IR files. I think it would be ludicrous to attempt that without automation, not only for the human effort involved but also because no humans could do that without introducing a large number of errors due to boredom and exhaustion.

 

So I bet there's an automated ratchet set of railroad-like tracks in Line 6 labs that moves a mic stand through 101*45 positions, with a 45 degree angling of the mic at each position.

 

Am I anal? Is it my CDO? (i prefer it in alphabetical order.) Whatever. Back to real life now....

 

 

Now add the memory footprint to it. The difference in file size of FW 3.15 and 3.5 divided by the number of IR files you computed. Some heavy black magic compression going on there.

[craiganderton]

I have found one possible exception to the "don't put effects between amp and cab." Here's an excerpt from the section on optimizing pitch-shifter quality in version 1.3 of my Helix book. It seems counter-intuitive, but try it. I was surprised, and don't really have an explanation of why this seems to be the case.

 

With pitch-shifters designed for single notes, playing more than one note at a time can give a hot mess of a sound. Playing cleanly improves the sound quality. By definition, pitch shifters that generate harmonies create more than one note at a time. For these, effects chain placement is crucial:

• If an effects chain includes effects that generate distortion (including amps), it’s usually best to insert the pitch shifter after distortion. However, if the sound quality is acceptable when playing chords without a pitch shifter, inserting the pitch shifter before distortion may work.

• Inserting the pitch shifter between an amp and cab often sounds better than inserting after an Amp+Cab. This is true for the non-polyphonic pitch processors.
• With a clean effects chain, most of the time it’s best to insert the pitch shifter at the chain’s beginning, because then it gets the cleanest possible signal.

[Schmalle]

On 6/12/2023 at 9:34 PM, craiganderton said:

 It seems counter-intuitive, but try it. I was surprised, and don't really have an explanation of why this seems to be the case.

Formants! Pitch shifting something characterful as a cab will put it's eq bumps and dents in unusual places in the spectrum and shift the resonance frequencies of the cab.