Linear Overdrive

[alex_6754]

Hallo
I noticed that each overdrive has its own characteristic voice. It's nice to have the replica of every historical object but an absolutely linear overdrive is missing. It could be a good addition ( and a simple job for you ). When I had Boss effects I used very much the Natural Overdrive that was very good and very linear,  didn't change the timbre and was usable with any type of amp simulation.
May be the better overdrive you made :-)
Thanks for your work.
Alessandro Pelati (Helix LT user)
Florence
Italy

[amsdenj]

Overdrives by definition aren't linear - they achieve their tone by using non-linear clipping to add overtones. But there are different kinds of distortion: low gain/high gain, low headroom/high headroom, hard/soft clipping, symmetric/asymmetric, mid-boost/no mid-boost, device used to create the clipping (tube, diode, MSOFET, LED), silicon/germanium, etc. All these things have a significant impact on tone. 

 is a good reference.

 

[MartinDorr]

The most linear overdrive in Helix is the volume block. But don’t get your hopes up too far. It does essentially the same as turning Drive up, except you know how many dB you pushed the input signal - and (obviously) you can put it anywhere in the signal chain.

In my experience, if an Amp model has a single Drive control, it is essentially a non-linear, Amp-specific input signal gain control. The Drive dial does not really change the Amp tone but its effect on the signal level that goes into the Amp model does. Whenever I tried I could get the same Amp tone by either turning the gain up in a volume block directly before the Amp, or alternatively the Drive control of the Amp model. The only difference you experience is how much each dial needs to move to get the same effect and the max and min ranges and resolution of the dials appeared to be different.

[codamedia]

On 7/25/2020 at 4:33 AM, alex_6754 said:

When I had Boss effects I used very much the Natural Overdrive that was very good and very linear, 

 

On older BOSS multi effects (circa the SE-70), the "natural overdrive" is said to be a drive that "simulates the tone of an over driven tube amp" which is actually pretty vague. Later variations (ME Series) suggest it is just a simulation of the SD-1 overdrive (that's not an effect I would call linear)... and now BOSS uses that term to describe the OD-3 overdrive. 

 

There we have it.... three different variations of the BOSS term "Natural Overdrive". 

Long story short, we need to know which unit you owned to know what you are referring to :) 

[HonestOpinion]

Another way to have minimal impact on the tonal character of the preset is to use one of the less over the top overdrives like the Teemah or an even simpler model like the 'Scream 808'. Crank up the volume on the overdrive with the drive turned down to zero,then slowly bring the drive up, leaving it on a relatively low setting.  This method can deliver overdrive with minimal coloration to the tone.

[amsdenj]

On 7/27/2020 at 11:38 AM, MartinDorr said:

In my experience, if an Amp model has a single Drive control, it is essentially a non-linear, Amp-specific input signal gain control. The Drive dial does not really change the Amp tone but its effect on the signal level that goes into the Amp model does. Whenever I tried I could get the same Amp tone by either turning the gain up in a volume block directly before the Amp, or alternatively the Drive control of the Amp model. The only difference you experience is how much each dial needs to move to get the same effect and the max and min ranges and resolution of the dials appeared to be different.

Depending on the model, the Drive control(s) could impact amp tone if they have bypass caps or bright switches. These bypass caps boost highs when the control is turned down low, but have less boost as the control is turned up. Past about 1/2 way, the bypass cap doesn't do anything. 

 

This is nice because it gives a nice sparkle when the drive control is turned down and the amp is clean. But as the drive control is turned up and distortion is introduced, the high boost is removed, avoiding ice-pick. 

 

Not all amps models do this. Litigator is one that I'm pretty sure does.

 

S-Gear has a High-Cut control in the power amp section that does the opposite. As the power amp is pushed harder and distorts, there is more high cut. When the power amp is clean, there's no high cut. This is great way of dynamically controlling brightness between clean and distorted tones and adds a nice warming feel to the way the amp responds.

 

[MartinDorr]

8 hours ago, amsdenj said:

Depending on the model, the Drive control(s) could impact amp tone if they have bypass caps or bright switches. These bypass caps boost highs when the control is turned down low, but have less boost as the control is turned up. Past about 1/2 way, the bypass cap doesn't do anything. 

 

This is nice because it gives a nice sparkle when the drive control is turned down and the amp is clean. But as the drive control is turned up and distortion is introduced, the high boost is removed, avoiding ice-pick. 

 

Not all amps models do this. Litigator is one that I'm pretty sure does.

 

S-Gear has a High-Cut control in the power amp section that does the opposite. As the power amp is pushed harder and distorts, there is more high cut. When the power amp is clean, there's no high cut. This is great way of dynamically controlling brightness between clean and distorted tones and adds a nice warming feel to the way the amp responds.

 

Thanks for that feedback. Will try that out some time in the future - and your info does not seem to contradict my experience with the BMan, with which I did the most detailed comparison of Drive versus Volume block gain effect. I believe the BMan does not have the bypass caps you were talking about.

[amsdenj]

Hard to tell. We don't know exactly what model Bassman Line6 modeled, what channel they used (probably Normal not Bass for guitar), or if it had a bright switch and whether it was modeled on or off.  It was not uncommon for Bassman Normal channel to have a bright switch across the volume control. A quick google search of Bassman schematics shows that most did. This was very typical of Fender amp designs, and most schematics I've seen of amps that didn't have bright switches had the bypass cap hard wired. Fender liked pretty scooped amps and that bright switch is a key part of Fender clean tone. Made them sell.

 

Update: looking at the model name "Tweed Blues Brt" it's probably got the bright switch on. 

 

 

 

[MartinDorr]

1 hour ago, amsdenj said:

Hard to tell. We don't know exactly what model Bassman Line6 modeled, what channel they used (probably Normal not Bass for guitar), or if it had a bright switch and whether it was modeled on or off.  It was not uncommon for Bassman Normal channel to have a bright switch across the volume control. A quick google search of Bassman schematics shows that most did. This was very typical of Fender amp designs, and most schematics I've seen of amps that didn't have bright switches had the bypass cap hard wired. Fender liked pretty scooped amps and that bright switch is a key part of Fender clean tone. Made them sell.

 

Update: looking at the model name "Tweed Blues Brt" it's probably got the bright switch on. 

 

 

 

Interesting, I definitely used the “Tweed Blues Norm” for my experiments and actually liked its sound better for JTV Strat models. Obviously ‘better’ is a very personal thing ...

I really appreciate you sharing your insight on this topic! It never hurts knowing a bit more about what a model dial really does.