H9 killdry and input levels

[studiodc]

Two questions (and a few follow-on detail requests) regarding killdry and input levels for the H9:

1. If I turn killdry ON and choose an effect preset with, say, a 10% wet/dry mix, am I going to still get the 100% wet effect anyway or will it be attenuated by 90%? 

2A. I tend to run my entire setup with signal peaks around -18dBFS (RMS) to give some headroom for peaks and transients. Will this same philosophy applied to the H9 cause me to miss out on the “meat” of the effects – in other words is the internal gainstaging set up to allow this sort of headroom-aware signal or must I be driving it really hot to get the best out of it?

2B. What is the internal computation headroom of the H9 compared to 0dBFS at the input? Is there any? 

2C. What is the recommended method for managing gainstaging inside the H9’s algorithms – even at -15dBFS RMS I can still audibly hear clipping in certain cases on certain presets (such as modulated delays with high feedback ratios).

Thank you!

[nickrose]

1. Killdry (as the name implies) just deletes the dry signal. So, if you have 10% wet/dry, you will get 10% of the maximum wet level. Killdry is mainly intended for use with parallel effects loops, where this behavior is appropriate. It also applies to a send/return from a mixer.

2A. Not sure what you mean by 18dBFS. Since the H9 has a soft clipper at its input, it is hard to judge its maximum conversion level (if this is what you mean).

2B. Ditto.

2C. Apologies for stating the obvious, but you do it by ear. Some effects are very dependent on the input material and the parameter settings, so there can be no hard and fast rules. If we were to make it totally clip-proof under all circumstances, the dynamic range would be severely limited. This applies to all effects, not just ours.

 

 

 

[studiodc]

Hi Nick, thanks for the quick reply (and on a weekend no less!). Here is some clarification to my questions, relative to your response.

nickrose wrote:

1. Killdry (as the name implies) just deletes the dry signal. So, if you have 10% wet/dry, you will get 10% of the maximum wet level. Killdry is mainly intended for use with parallel effects loops, where this behavior is appropriate. It also applies to a send/return from a mixer.

Got it, that’s what I expected and what my ears were telling me. So I’ll design the programs with that in mind.

nickrose wrote:

2A. Not sure what you mean by 18dBFS. Since the H9 has a soft clipper at its input, it is hard to judge its maximum conversion level (if this is what you mean).

When I refer to -18dBFS I mean that I usually have the average analogue levels (either via source level or input gain adjustment) such that the A/D converters are rendering the RMS level of the signal at around that level on the digital meters – so for instance in a digital rack effect or in the DAW I would usually have the track level peaking between -15dBFS and -12dBFS and thus the RMS would be from -18 to -15dBFS. This leaves 12 to 15 dB of headroom for transients before clipping digitally. 

The EBU standard is -18dBFS = 0VU for professional audio gear in a +4dBu referenced studio setup.

Now, I know the H9 is not a studio pedal, hence my question – if I feed it with an analogue signal level and input gain combination such that the average rms level of my incoming signal measures -18dBFS on the H9’s own input level meter, will the effects sound as they are intended, or are they designed for guitarists who intend to drive the pedal just under (and possibly into) clipping as a matter of course? The reason for this question is related to the details for 2C, below.

nickrose wrote:

2C. Apologies for stating the obvious, but you do it by ear. Some effects are very dependent on the input material and the parameter settings, so there can be no hard and fast rules. If we were to make it totally clip-proof under all circumstances, the dynamic range would be severely limited. This applies to all effects, not just ours.

Yes, of course.

Presets only store output gain, but not input gain… and if there’s clipping caused by the internal mathematics of the preset algorithm, clamping the output level of the preset won’t reduce the clipping . So I need a globally low input level to leave internal headroom – the same as I’d do with profesional gear in my studio.

If the H9’s internal algorithms are just fine with a significantly lower input level such as referenced above, and I’ll still get good sonics on the distortion effects, the levels will still trigger the pitchshifting and attack detection, etc… then I’ll just run it with 12-15dB of input headroom.

So I guess the question could be simplified as: “even though the manual says to run the input levels as hot as possible, what do I lose or risk losing by running them with 12-15dB of headroom”? 🙂

[nickrose]

Sorry, won't be able to get back to you until Monday or Tuesday (weather permitting).

But, I expect that what I'll say is that the "input level meter" is there to show if people are seriously underdriving the unit (which often happens), and is not a comprehensive dynamic range indicator. The H9 is a guitar pedal and not a studio line level instrument – ears are usually best.

Our problem is that we need a good input level to overcome noise produced by the high input impedance (and the A/D conversion). Further, we have a non-linear soft-clipper on the input, and the effects are also very sensitive to the source and the settings . For all these reasons, the figures you seek are not available and, if they were, would vary from effect to effect.

.

 

[studiodc]

nickrose wrote:

Sorry, won’t be able to get back to you until Monday or Tuesday (weather permitting).

No worries.

nickrose wrote:

But, I expect that what I’ll say is that the “input level meter” is there to show if people are seriously underdriving the unit (which often happens), and is not a comprehensive dynamic range indicator. The H9 is a guitar pedal and not a studio line level instrument – ears are usually best.

 

Gotcha. I see what you mean. Ok, thank you for the clarification!

[Author]

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