Community: Message List - (HD500) Double guitar signal to one amp model?

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Mon, 14 May 2012 13:05:22 GMT

Re: Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 23:37:56 GMT

Thanks for the reply ..

and for the very useful measurements..

If you think about it, the input signal is a couple of analog volts oscillating in a wave pattern. By the time it hits the 'amp' it has been converted to a digital 1's and 0's that correspond to that wave pattern. It is not like you can say "The input voltage from my guitar was 2V and by the time it came through the HD input stage and hit the amp it became 4V: it is comparing apples with Aardvarks.

You say that the input signal once converted into numbers is not more than a waveform ..

ok, but among the parameters used to describe a waveform there is also its amplitude, and that is directly proportional to the strength of the input signal..

After all, should not the POD HD give us an accurate digital representation of what happens in reality with amplifiers and effects? ..

I take advantage of this post to write another thing:

For years I use the Line6 products, and so ultimately I think they are valid ..

I started with the first bean and now I find myself with the HD500 ..

It is a love hate that has lasted a long time .. and then in the end, I'm an old affectionate ..

But what, I do not like and that I often found on dedicated forums, it is an attitude blindly defensive of the product.. it is hard to get right to the point and have a simple piece of information, as if there are any important secrets, things to be washed only at home .. or a reputation to defend ..

I simply asked if, in relation to the input settings, my signal is doubled, remains the same or if it is halved .. and in response I have seen many different theories, but no one gets to the point, (except mdmayfield, jimsreynolds and more or less silverhead)..

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 22:26:36 GMT

Thanks for your replay mdmayfield, but I have a slightly different opinion

Changing the input gain (mixing 2 identical inputs) will cause the amp to respond differently, but only if you don't compentsate for it at the amp's Drive or earlier.

for example, if I wanted to obtain (approximately) the same level of distortion and timbre in 2 situations:

1) input 1 = guitar, input 2 = guitar -- amps drive = say on 6 or 7 (or whichever is)

2) input 1 = guitar, input 2 = aux -- amp drive = higher than the one above to compensate..

I would not get two identical sounds

in my opinion the exact setting (not relative) of the drive, influences the tonal response of the amplifier (modeled or real) ..

If, for a different example, I set a very high drive (no matter which input settings), and turn down the volume of the guitar with a volume pedal, to get a clean sound or crunch, I get a timbre ..

if instead, my volume is full open, and I lower the drive to search for the same sounds mentioned above, I will obtain different results definitely..

I heard the HD400 sounds better than the HD500 .. if it is true (I really don't know), I wonder if this is due just to the different routing of the input signal between the two machines..

if the models contained in the HD400 are the same of the HD500 (and they are), why the HD400 takes a single input source to drive them and the HD500 takes 2?

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 20:59:31 GMT

that's a good question. I would test this with the Hard Gate, and just set open threshold all the way down so the gate stays open. I would guess there would be no difference.

Case 1) Input 2 Variax and Hard Gate enabled:

The signal from Input 1 is summed with the signal from Input 2 when it hits the hard gate. Since Input 2 is basically null, the mono signal going into the gate is identical to the Input 1 signal. Since the gate is basically doing nothing, the output signal is equal to Input 1. When it comes out the gate it is doubled with equal signals left/right. This doubled signal is summed to mono when hitting the amp block. Since both signals are active, the summing boosts the volume that the amp receives. So the signal hitting the amp is equivalent to Input 1 x2.

Case 2) Input 2 Same and Hard Gate disabled:

The signals from Input 1 and 2 are identical. When they hit the amp block they are summed together. This summed signal is equivalent to Input 1 x2.

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 16:20:09 GMT

100% agreed Mdmayfield.

I am wondering about something: with input 1 and input 2 active, the volume increase is expected to be the same if you place a mono block effect before the amp model, in relation to if you just let the two signals hit the amp model separately (like being parallel)?

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 15:25:26 GMT

^ this guy knows what he's talking about.

Re: Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 15:23:27 GMT

well if you change the input but don't adjust the amp gain, yeah, there's going to be a difference in response...kind of like rolling the guitar volume knob down a tad - it'll have an effect on your response...

Re: (HD500) Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 13:32:09 GMT

As far as I can see, the difference between using 1 vs. 2 inputs is just doubling the input gain. Usually doubling in that context means a 6.02dB difference, which agrees with what jimsreynolds found in matching level to the amp.

I could be wrong, of course, but my experience so far has been pointing toward that explanation.

Regarding the different experiences meambobbo and hurghanico described above (the amp response being identical vs. clearly changing), I think those can be reconciled like this: Changing the input gain (mixing 2 identical inputs) will cause the amp to respond differently, but only if you don't compentsate for it at the amp's Drive or earlier.

Similar to how turning on a clean boost pedal will change the overall tone of your entire (guitar + effects + amp) system and the way it interacts, but as far as *just* your guitar goes, separate from the FX and amp, the boost pedal doesn't change the tone; only the amplitude.

Jstock, your experience makes perfect sense to me - I did the same thing. When you change the input, you basically put a 6dB cut on the input to all your patches - which were dialed in to expect 6dB more signal from the guitar. You should be able to either leave them the old way, or change the inputs to single and add a 6dB boost with a pedal effect before the amp (or up the Drive level by ear) to arrive at an identical sound.

Personally, I just started making new patches with a single input (sounds fine when making them from scratch), and left all my old ones the way they were.

Re: Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 12:03:19 GMT

+1 Jimsreynolds

"I guess you need to make sure the input signal is not so wussy that you lose balls but not so strong that you lose definition"

I set all my patches with Input1 = Guitar and Input 2 = Same. Was 100% happy and played loads of live gigs this way. I then decided following a previous discussion to set Input1 = Guitar Input2 = Variax. I was happy until I played a gig and found that my tones had lost their, as jimsreynolds said "balls". Rather than adjusting each patch I simply went back to the original setting.

What am I trying to say here? Set your patches up with each Input 1 and Input 2 set consistently and you can't go far wrong. If you find that your guitar is making the patch sounds muddy or over distored or alternatively missing something in the balls department then yes your going to have to look at this setting but only once you have tweaked all the other parameters that are available to you.

As for which setting produces the closest reproduction to the real amp - that I believe is going to be very tricky to answer given the number of parameters.

Re: Double guitar signal to one amp model?

support@line6.com — Fri, 27 Apr 2012 10:30:52 GMT

In this specific case: the signal level of my guitar (no matter how big or little is), how arrives at the amp? .. equal? Double? half? ..
This is the only real official information I'm looking for!... I'm not asking for the moon, but only for simple numbers
Then I will decide case by case whether to use one solution or another based on what comes to my ears, but always knowing what I'm doing

If you think about it, the input signal is a couple of analog volts oscillating in a wave pattern. By the time it hits the 'amp' it has been converted to a digital 1's and 0's that correspond to that wave pattern. It is not like you can say "The input voltage from my guitar was 2V and by the time it came through the HD input stage and hit the amp it became 4V: it is comparing apples with Aardvarks.

I think I see what you are shooting at ... how do you get unity gain through the input stage?

The closest I got to when balancing up my 4CM: I compared

Guitar - > amp

with

Guitar -> HD Input -> HD FX Send - > Amp.

I did it with a true bypass box so I could flip between the two setups and listen to the difference. I do know that, with Input 1 = Guitar/Input 2 = Variax, there appeared to be a volume drop between the two of around 6dB (which I corrected with a Studio EQ to boost) but I have never gone back to double check whether I got Unity gain with Input 1 = Guitar/Input 2 = Same. For my application (4CM, mono , imperative to avoid input clipping) it really wasn't an issue for me.

I gotta go with the rest though on the ears thing. Most 'real' amps 'high' inputs are around 1M and low channel around 68K IIRC. I guess you need to make sure the input signal is not so wussy that you lose balls but not so strong that you lose definition. Its good to have a good theoretical idea as to what is happening but in the end you are interfacing with analog ears. You can set the input settings per patch so it's all good