Gibson HP-4 "Transient Suppression"

[freddietane]

hi Forum folk -

 

Does anyone have any insight into the circuitry used in the 2019 Gibson HP-4 dip switch #5 which turns on/off what they call "Transient Suppression"?

 

The documentation provided by Gibson says this:

 

Transient Suppression (Off=Out of Circuit / On=In Circuit)

Transients = A sudden, loud spike from the initial attack phase of sound.

Example: Pick attack or noise.

ON = Works to suppress the harsh transient noise or spikes which A/D convertors

can sometimes pass when recording directly into the high impedance input of a

DAW interface or digital mixer. Due to the inherent input compression of typical

guitar amplifiers, this circuit is virtually transparent even if left on in the circuit.

 

When asked whether they had a circuit diagram to study:

"We don’t have a file that outlines the precise circuitry of that PCB."

 

I have yet to do an experiment on my DAW/Interface, but am wondering if anyone knows what this is actually doing, electronically.

 

Thanks!

[Anderton]

Check out this article I wrote for Guitar Player, it explains what transient suppression is all about.

 

I came up with this circuit years ago, so it's in the public domain. Gibson recognized the potential, though, and included it in several Les Paul Standard models. The main use is when feeding guitar into digital audio interfaces, because it lets you obtain a higher average level with a more predictable dynamic range. In a way, it acts similarly to how analog tape "absorbs" transients.

[MikeRivers]

Understand that the Transient Tamer doesn't raise the output level of the instrument, it reduces the crest factor - the peak to average voltage ratio - which allows you to turn UP the input gain of the amplifier or recording interface. But like any limiter or compressor, if you want to end up sounding louder, you need to add amplification AFTER the peaks are rounded off.

 

You can expect the tone to change, so you may feel a need to fiddle with the tone controls after clipping. There's nothing wrong with that. The Transient Tamer isn't a miracle cure for a problem you didn't realize you had, it's just another tool that happens to work well for a particular kind of playing.

[Anderton]

You can expect the tone to change' date=' so you may feel a need to fiddle with the tone controls after clipping. [/quote']

 

You probably wouldn't hear a difference. The LEDs have a breakdown voltage of around 2V, so only the highest transients, which are very short, will be clipped.

 

The Transient Tamer isn't a miracle cure for a problem you didn't realize you had, it's just another tool that happens to work well for a particular kind of playing.

 

I'd say it's more for a particular type of signal chain, i.e., feeding a digital processor where you want to avoid clipping at all costs. And because you do, it's common to turn the volume down; so using the transient tamer allows for (as you pointed out) a higher average level.

[freddietane]

Thanks Craig, (and Mike), for your insights and information about this circuitry! Very interesting, and look forward to utilizing it in a tracking situation where I'm using all-DAW-based signal chain. I like how Craig describes it as being able to "obtain a higher average level" from the direct-input guitar. Nice! Great GP article too! Enjoy reading your columns there. Rock on!