Touch-Sensitivity: Myth or Reality?

[The New Steve H]

People like to say amps are "touch sensitive." But people BS a lot. I'm wondering what the guys who actually make amps think, so here I am, asking.

When I showed one of my amps to my guitar teacher, while he was raving about it, he said the one problem with it was that it made mistakes obvious.

I was playing tonight, and I was focusing on making the guitar sing. By that I mean carefully sculpted notes instead of blasting chords. More like B.B. King than the Troggs, except that B.B. King can play well, and I can't. I was struck by the way notes just plain disappeared when I reduced the pressure on the strings by miniscule amounts, and I thought a lot about things like tiny bends that are too small to bother putting in tablature, yet which make the difference between flat playing and real music.

What I want to know is, are my perceptions accurate? It seems like store amps are a little bit like the clutches in Japanese cars: either on or off. A nice homemade tube amp appears to allow for a ton of additional subtlety, but it seems like it can also be discouraging, because it won't carry you by covering mistakes.

Does this sound right, or is it just one more indication that I need to cut down on sniffing glue before practice sessions? Not that I would pay any attention.

[xtian]

I think we're talking about two separate phenomena. To me, a touch sensitive amp is one that sounds clean when played gently, and transitions smoothly into harmonic overdrive when played hard. It's sensitive to dynamics, with distortion as the variable.

I think a rig that does not hide your mistakes is usually one with no effects. No delay and no reverb, especially. Plug guitar right into amp, and turn it up. That's naked. That's when you have to learn to be a good player. That's honest and brutal.

[Phil_S]

In my limited experience, touch sensitivity is real.

Some amps demonstrate a very low range of dynamic response regardless of how hard or soft you pick the strings.

Other amps will clean up very nicely to a light touch (pick attack) and get progressively more gritty as you dig in harder. All along the tonal range a touch sensitive amp will retain the tone that makes that particular amp different from another amp. All this can happen without over working the volume pot on the guitar.

[dorrisant]

I'm surprised the teacher didn't appreciate the way a touch sensitive amp will punish you for sloppy playing... Get it right or it sounds like poo. In my experience someone who plays on a touch sensitive amp for a while learns to tighten up their chops thus becoming a better player with the added reward of learning to control the nuances. Why would a teacher not appreciate the results?

[The New Steve H]

He did appreciate it. I made it sound like he was complaining, but he wasn't.

[Littlewyan]

I agree with the others, touch sensitive is where you can clean up a bit by playing lightly then blast out full distortion by hitting the strings.

With regards to the amp showing your mistakes, again thats a good thing I think. An amp that covers up mistakes is mostly due to a lack of clarity I think. Which isn't completely bad, in some cases it can sound better than having too much clarity. Depends on what you want. Its all subjective!

I know Randy Rhoads admitted to hiding behind distortion with some of his licks. Then again Randy Rhoad's version of playing badly is our version of playing good.

Also the way some notes disappear if you lower the pressure on the strings can be just a lack of gain. Again, you may prefer that as it makes you work harder for that note

[Theashe]

This kind of idea:
https://www.youtube.com/watch?v=n7HBDKfsN4c&t=1m32s

Would the choice of bias point for V1 in an amp be a large contributor to its "touch sensitivity"? Putting aside that there are other things like sag and fixed vs cathode biasing on the power tubes that I've heard associated with "touch sensitivity", a hot or cold biased preamp tube would begin asymmetrical clipping for much smaller input signals.

[stretch2011]

I play naked....
By that I mean no effects period lol
Don't get me wrong at times I like some verb, but I am just fine without it. Definitely beefed up my chops.

Everyone is right, clean to mean with the picking intensity. But there's another factor in picking lightly. You get subtle harmonics. Its especially good with non-wax potted pick ups ( burst buckers 1&2 for example).

The note fading out is due to lack of sustain. There are a few ways to cure that. Turn the volume up or press the strings down with more pressure. But if you turn the volume up you can overdrive the amp. So you would need a higher wattage amp to stay cleaner louder.

Most of this is subjective, because if you cannot hear it then to you, it is not there.

Bottom line, it is all in your hands!

[sliberty]

Words matter, and guitarists don't just BS, they also misuse words. So, always start with a definition.

I've heard "touch sensitivity" used to refer to how how well an amp can clean up with your playing dynamics, but I have also heard it used to refer to how easily an amp will break into infinite sustain / feedback.

They are both real, and some amps do a better job of each (or both) than others will.

On the other hand, when I think of what makes an amp "cover up my mistakes" (or not), it has more to do with how quick of a response the amp has. An amp that can track with your pick attack dynamics fully will not hide much of my sloppiness. But a more mushy, (maybe Tweed-ish) amp might be more "forgiving" of my lack of technique.

Lots of opinions, all valid, as long as we are talking about the same thing - so define first, comment later

[The New Steve H]

I don't really know what the tweed sound is. A friend of mine built a tweed Champ from a kit, and I played it. The dirty sounds were okay, but it seemed like it was not possible to get a sound that could be considered clean or open.

I don't recall exactly what sort of Champ it was or how it differed from an original Fender.

[sliberty]

My comment about Tweed-ish had to do with the way the power supplies tend to be under powered, resulting in slower response / recovery. This can be heard in the form of mushy bass notes, softened pick attack, high degrees of compression, and other audible effects. This is somewhat the exact opposite of a BF Fender which tends to have a quicker response, as does my monstrous HiWatt Custom 100.

[jjman]

Check out Dave Edmunds' "Baby Let's Play House." Especially the last 5 seconds. No better example in a song that I know of.

https://www.youtube.com/watch?v=5NHjEW01DsM

[teemuk]

I was struck by the way notes just plain disappeared when I reduced the pressure on the strings by miniscule amounts, and I thought a lot about things like tiny bends that are too small to bother putting in tablature, yet which make the difference between flat playing and real music.

Compression (whether gain compression or clipping limiting) can hide weak sustain resulting from, no offense, sloppy touch. So, adding compression can carry over the mistake of not getting strings to sustain properly.

One can achieve compression by simple means of signal clipping, "overdrive". Peak points of the signal get clipped so amplitude and overall loudness averages closer to level of weaker signal portions (the decaying notes). Crank up volume and you have artificially increased sustain of your instrument.

But there can be signal clipping that merely increases harmonic distortion in simple, predictable and boring pattern, or there can be clipping that to great deal has interactivity with the input signal and harmonic distortion changes its pattern dynamically. Whole books have been written on the topic.

There's your "touch sensitivity" or "feel" right there in those little nuances of circuit operation.

What I want to know is, are my perceptions accurate? It seems like store amps are a little bit like the clutches in Japanese cars: either on or off.

Your perceptions are correct. Amplifiers are different.

[boots]

To me, touch sensitivity is dynamics. A lot of SRV's stuff is very dynamic. For instance, I think "Lenny" has a lot of good examples of touch sensitivity.

[pdf64]

A prerequisite for touch sensitivity is a smooth transition into distortion; that's another way of saying its clean power output, ie for a given (lowish)% thd, is not as much as it could be.
That means that the amount of global negative feedback on the power amp has to be fairly low.

Given that, touch sensitivity probably requires that the differential in power output between max clean and max overdriven is fairly low, which may be achieved by means of power supply sag (ie at screen grid / plate nodes).
The 5E3 tends to put out about the same overdriven power as clean (though 'clean' may be a judgement call); due to sag on the plate and screen grid nodes, and squish from cathode bias exacerbating the reduced HT voltages.
It's the polar opposite of a classic solid state amp with well regulated supplies, which should put out twice the power when overdriven as clean.

This begs the question 'why not just use a compressor set to an extreme limiting effect?'.
I think that the difference is that low dynamic range of the touch sensitive guitar amp facilitates the player to choose the degree of distortion by means of modulating their playing technique, in terms of controlling the attack / output of their instrument.
Whereas a limiter shouldn't add such obvious harmonic distortion to the signal.

Given a suitable amp, the player requires a reasonably nuanced technique, and musical genre / style allow room for that to be exhibited.