Hi guys, sorry, no kidding here:

I really think these are important things not stated (or in some cases not clearly stated) in the manual, that you need to know to start seriously programming your POD HD

I ran some serious tests on my Pod HD 500 and here is what I found out,

I'll try to be as synthetic (but complete and clear) as possible, but this is going to be a long reading so sit down and take your time or just go surfing somewhere else

§ § §

1) the "famous" [input-1: guitar / input-2: variax] setting gives you different levels of signal depending on the position of the first *mono* effect block you use (amplifiers included), in particular you LOSE 6dB in the "pre" path in comparison to the path A/B or post path

(note that this is not the same as saying that you gain 6dB with input-2 to "same", read on).

[ if you don't know what I'm talking about just go and read this thread: What every HD500 owner needs to know!

http://line6.com/support/thread/74045?start=0&tstart=0

then come back here to hear a different opinion on the matter]

first of all, try it out:

- connect a guitar to the guitar input and the Left output to a full-range linear amp (or use your headphones)

- recall a "new tone" default blank patch

- set input-1 to Guitar and input-2 to Variax

- set mixer channel A fader to unity (0.0dB) and pan to center

- set mixer channel B fader to mute

- setup a noise gate* with the threshold set to 0% in "pre" position

(with this setting this IS a unity gain mono fx block)

- play thru it

- now if you bypass it, you'll hear that it  looses 6dB of level when it's active (I initially thought this was noise gate's fault, but it's NOT)

- now re-activate the noise gate and move it in A or "post" path

- now if you try to bypass it you'll hear that it does NOT loose any dB

- try moving the block back and forth ** between pre and A or post paths and you'll hear more level in path A or post than in pre

[please note that this was edited some minutes after posting for small but significant typo's]

this was already found out at least by hurghanico here: http://line6.com/support/message/403287#403287

but it's so important that needs a dedicated and more detailed thread.

[* you can repeat the experiment with other mono effects instead of a noise gate but keep in mind that, if you want to clearly hear a level difference, you need a mono unity gain (www.music-dictionary.org/unity_gain) effect, for example:

- a tube comp with thresh 100% & level 2% settings will work just  as the noise gate above

- an fx loop block with a mono cable connected between send and return will work just the same (but also read point 2 below)

- do it with an amp with medium-low gain and, moving it between pre and A or post paths, you'll hear a significant difference in gain/ovedrive/distortion here, not only level difference

** Notice that I found an intermittent bug here that could change the result of the test: see point 3) below]

OK now that you heard it, let's see it in detail;

these are the REAL schemes of the pod and fx blocks routing, yes it's done by hand and I love it ;-)

As you can see the pre path is a "dual-path"

while A, B and post are all stereo paths;

at the splitting point, where the path A and B are born,

the signal coming from input-1 is splittted to the Left and Right channels of the path A

and the signal coming from input-2 is splittted to the Left and Right channels of the path B;

furthermore all fx blocks have TWO inputs and two outputs and the mono blocks do attenuate by 6dB and sum their inputs, then process the result and then split their mono output to both outputs of the block;

for those who don't know, notice that:

- summing two identical signals or doubling a signal, gives you the same signal with 6dB more

- "splitting" means duplicating one mono signal to two "routes", practically doubling it;

[and two side-notes:

- the "stereo dry & mono wet" effects are for example the pitch effects and the "dry" type delays, I'm not considering this type of effects in this post, but they work as expected from the scheme you see above;

- the mixer control named as "pan" is actually a "balance" control because if you move it to one side (e.g.: left) it acts on the stereo or dual mono signal by doing NOTHING on that side (left) and ATTENUATING the opposite side (right)]

So, if you only activate input-1, in the pre path, the first mono effect is attenuating the input 1 and 2 and summing them, but, since input-2 is actually silence, you loose 6dB;

in A and post paths the effects are receiving a doubled signal on L/R so for mono blocks attenuating and summing gives them the right mono signal level to process

so using "same" or "guitar" for input-2 does not mean to gain anything, but having a constant doubled signal wich is compensated by a 6dB attenuation in each mono summing it encounters in his flow

please note that I am NOT saying that using only input-1 is wrong, you just need to know that this can give you different gain results depending on the position of the first mono effect

with only input-1 active and the same parameters values, this:

is giving you more distortion than that:

and this is something that can not be ignored

...don't know how to be more clear than that

§ § §

2) the fx loop block is LOOSING 5dB on the send with the switch in the "stomp" position.

What I wrote untill here were just implications of how the routing of a complex multifx (like the pod hd is) can work; but now we go to something couter-intuitive and *guiltily* not stated anywhere in the manuals.

if you connect anything gain related (compression, distortion, preamps, envelope followers) into the fx loop you're getting the *wrong* result

this includes the very popular four-cable-method (http://line6.com/support/docs/DOC-2504)

Now I'm going to explain this and give a SOLUTION to the problem, let's see the details:

I have to say thanks to this post from anglepod (to whom I rashly replied that he was wrong and I'm gonna ask him his forgiveness for that): http://line6.com/support/message/393494#393494

and that I totally agree with the original post by jimsreynolds in this thread:

http://line6.com/support/message/397759#397759

but here I'm giving a different and easier solution I think

Anyway, what I measured is that, with the stomp/line switch on "stomp" and input pad on "normal", the guitar signal is attenuated by 5dB (approximated with no decimals) along his route from the input, thru no fx and then to the send jack, and is quite-compensated by gaining back 4dB at the return;

[this additional 1 dB difference (again approximated with no decimals) from -5 to +4 is even more inexplicable and could be only on my POD HD 500 unit, so you'll need to test your own]

furthermore, switching the stomp/line switch to "line" is (correctly) giving 12dB to the send AND compensating by attenuating the return by the same amount, but is "suffering" from the same -5/+4 attenuation/compensation, so you get +7dB at the send (+12 -5) and -8dB at the return (-12 +4) as a result;

I guess the reason for this attenuation/compensation is to put the unity gain at approximately half-way between a stomp and a line reference level, but this choice is wrong (or at least badly implemented and guiltily not documented):

common sense: when I connect my guitar directly to any guitar input (stomp-box or preamp) I have a "stomp" signal level, so:

- the stomp position of the switch should definitely be at unity (=same level as the guitar itself)

- consequently the "line" position should be +12dB on the send and -12dB on the return

- then we should (like anglepod noted) have the ability to give or take dB's on the send as well as on the return via some software trims

the SOLUTION to the problem is:

- set the fx loop switch to line

- set the send to -7 dB and the return to +8dB (could be e.g. -6 / +6 on different machines)

now you have a unity send and a unity return AND you can boost or attenuate both if you need it!

[

EDIT:

there are other solutions to this problem

see my post on the 9th of january

]

Then combining my 1) and 2) points:

if you connect a cable to just one of the fx return jacks (this works also with the Right return, not only the L/mono) the fx loop block acts exacltly like a mono fx block (see diagram above), so it attenuates and sums its inputs and then sends the result to the send jack (to both pins of the TRS jack to be precise), and then splits the return to both outputs of the block

this means that if you are using the [input-1: guitar / input-2: variax] setting and you put an fx loop in default mode into the "pre" path with for example your amp's preamp into it, you are loosing 11 (or 12) dB of gain!!

§ § §

3) I'm not spending time on this point because I've still to test it more but I'm pretty shure I found an intermittent bug on the action of moving an effect on the signal chain that complicates the investigation on all the things you read above (but doesn't deny them)

if you try to replicate the steps at the beginning of my point 1) above, if the bug presents itself (and it's not always), when you move an effect from the "pre" path  to path A it works correctly giving you 6dB more, but when you move it back to "pre" it doesn't go back to minus 6dB; if you save the patch and then move to another patch and come back using the pod pedalboard and *not* with the edit software, you can start over untill you move the effect again forth and back

Of course I'll submit this as a support ticket as soon as possible

4) OK, after all this reading, I'm asking something more to you;

please, since it took me days of work ("fortunately" I was ill at home in these holidays) to test, re-test and write all of this in english (which is not my mother language), you owe me this:

- re-read it (I'm not kidding)

- ask me any question you have (but don't expect me to be ill at home to much :-) )

- do all or some of the same kind of tests and then confirm, correct or deny my results

OR just shut-up, please ;-)

I hope to have been helpful to you... all that work was helpful for me!

thanks for reading and a happy new year!

bye

Lore