Questions about soft overdrive

[akis]

I do not have a good quality all tube amp here, so I would kindly ask anyone that does, or knows, to help me:

Turn guitar to max, on the clean channel, turn the gain up so that it is not clean anymore but overdrives. Make sure that playing a chord clearly overdrives. Now play a single note, eg open low E and hear the "fuzz" of the overdrive. The question is how long does it take before the tone looses its fuzz and reverts to pure sinusoid? Is it possible that with this very soft overdrive the tone will continue to maintain its "overdrive" sound as the note dies?

[phatt]

Hi chum,,
Valve or SS makes little difference once you understand circuits.

The best way to describe what I think you Ask is called *Compression* and Valve Amps tended to do this automatically. (I'll leave it to better minds to describe that)

In simple terms any circuit that has the right amount of gain in the right places in the signal path will likely have that effect.

IME the fuzz/distortion is simple enough to achieve but it is all those in between sounds that is much harder to achieve.

As someone once stated the magic of famous valve stuff was half wave clipping followed by square wave clipping.

Which fairly accurately describes what happens with SOME (Not All) Valve circuits.

If you are looking for dynamic compression (think SRV clean compression) then it is not a simple matter of adding MORE Gain as most assume it is more about tone shaping from PU all the way through to speakers.

Few seem to grasp that tone shaping before and after ANY KIND of Distortion is what makes magic.
The mojo has very little to do with unobtainable parts that are no longer made.

In the case of SRV it was more likely the Amps lack of ability to produce gain that made magic (which equates to magical Compression), couple that with ****UNderwound PU's**** meaning stock PU,, NOT overwound Texas BS that Fender propaganda proclaims in magazine hype.

To get nit picky: all the above only worked well if the Amps where LOUD.

meanwhile the average kids wants to do that at 250 mW in the bedroom and of course You have no hope of reproducing that magic unless your Dad owns the Bank. :cheesy:

Phil.

[QReuCk]

Phabb, not sure it is what the OP wants to achieve here. My english is not that good so I might be mistaken, but I think he wants the harmonics of the overdrive sound to continue being generated when the note decreases. That's exactly what tube enthousiasts DON'T want to happen (they usually want the harmonics being generated only when feeded with strong signal and prefer to be able to control the amount of distorsion from the volume pot of the guitar). Here the OP for personal taste wants the oposite and I think that's fine (colours and tastes, you know...).
Bad news is that the way clipping works is input volume sensitive. So when the note fades, the clipping also fades. This is not that much noticeable when using a lot of gain, but when using a slight overdrive you clearly here it.
Two ideas here using a pre-EQ then the tone stack of the amp:
1° bass boost a lot with the pre-EQ use very moderate gain on the clean chanel then boost the highs/high mids on the tone stack. This will clip the lowest harmonics and fundamental a lot, producing a very noticeable fuzz that doesn't need a lot of gain to be interpreted by your hears as fuzz=> as the fuzz is noticeable even at low input volume, you'll here it a bit longer when the note decreases.
2° try the opposite: cut the bass bands with the pre-EQ, boost a bit the mids to high mids and cut the highs above 3KHz, you don't need them to compete with the harmonics your preamp will generate. At the preamp, you can get away with quite a lot of gain, cause you prevented the bass bands to clip too much (they are not clipped) and the mid bands generate harmonics that do not compete with the high harmonics from your instrument (cause you did cut them at the pre-EQ stage). You will then have a lot of compression but not that much fuzz, except when playing very harmonically rich chords (like 9th or 13th). Use the tone stack to adapt your averall tone and reemphasise the bands you did cut before the clipping stage.

Decide what you like best and fiddle with both the pre EQ, gain and tone stack to obtain what you are after. You might find a few new sounds you like, even if they are not exactly what you were after.

Pre EQ can be anything from trying different pickups/pickups configuration, any coloured booster or a stompbox equalizer (some prefer parametric ones, but graphical ones can do the job and are usually easier to find).

Hope that helps a bit.

[J M Fahey]

Answering literally what the OP asks, if you raise the clean channel volume until the power amp clips on a power chord (which is not that much distortion to begin with) , and then play a single note, it will clip less or even not at all, because usually a single note is much weaker than a full chord.

It depends a lot on how far beyond the edge you went.

If it clips, it won't do so for long,, maybe a couple seconds, and then it will "die" clean.

If it continues dirty until quite low levels, you have probably blown your speaker, sorry.

[akis]

Perfect. How much distortion would you expect out of the clean channel, assuming no pedals inserted in between? Would you get the distortion where compression is very evident, where the attack caused by picking is almost lost completely ? Or would it overdrive but never really "distort" even at full gain ?

[phatt]

I know it's hard to describe sounds in words,, even harder because this is just so complex and even worse there are so many ways that achieve the same basic outcome.

How much distortion you get from the clean channel is totally dependent on the PU, the preamp gain, No not the Gain knob on the front, I'm talking about the presets the designer used when the Amp was built.
How many preamp stages are used how the interstage system eq is setup.

was the Amp designed for Hard rock/Metal/Blues.

The list of possible configurations is close to endless. :loco

Note *QReuCk* comments where he quite obviously knows just how tone shaping dramatically effects the end result. :tu:

So how about I give two scenarios and you pick which one best fits what you desire to know?


1/ the ultra clean (ish) ODrive amp that never really fuzzs ,, just sweet singing sustain/compression/limiting.

2/ Heavy metal type sound where no matter how soft you pick the distortion is always much the same.
Cheers, Phil.

[J M Fahey]

Perfect. How much distortion would you expect out of the clean channel, assuming no pedals inserted in between? Would you get the distortion where compression is very evident, where the attack caused by picking is almost lost completely ? Or would it overdrive but never really "distort" even at full gain ?

Not much.
Definitely not a "compressed" one, nor long sustain or attack squashing.
"Clean" channel gain is *usually* set to an "average" guitar, played by an "average" guitar player, starts clipping around 6 or 7 on the volume control.
Why? : so a weak player/pickup/thin_strings still have a little extra gain available to compensate (7 to 10 ) while a loud player will still have clean sound up to, say, 5 .
That with a true Audio/Log volume pot, of course.
So in practice you can overdrive a Clean channel by 6 to 10dB, not much.

[Roly]

The question is how long does it take before the tone looses its fuzz and reverts to pure sinusoid? Is it possible that with this very soft overdrive the tone will continue to maintain its "overdrive" sound as the note dies?

The short answers are; until the input signal falls below the clipping threshold, and no.

We talk about amplifier "headroom" because a signal can rise until something, generally the power supply voltage (but it may be artificially induced) limits and clips the signal.  It's a bit like bouncing up and down on your bed - your head hits the ceiling, or it doesn't.  If you hit it hard you get crunch, hit it softly you get a bit of grind, but if you don't hit it at all you just get the same signal louder.

To continue the analogy, what a compressor does is adjust the height of your bounce so you always hit it with about the same force, hard, soft, or not at all depending on how you set it; but this results in a signal that doesn't die away smoothly because the compressor is twiddling with the volume control trying to keep the output, and your loudness, constant.

@phatt and @QReuCk are saying very similar things; that the nature or character of any distortion produced depends on the proportions of the frequencies going in (pre-EQ) and how they are proportioned again after distortion (post-EQ).  Very few (if any) rigs go to the extent that @phatt has explored in his builds to provide a rich variation of both pre and post distortion EQ.

The mojo has very little to do with unobtainable parts that are no longer made.

I'll harden up on that - its has absolutely nothing whatsoever to do with ... etc.  Anybody who tries to sell you a stomp or magic component X that will turn you into SVRV or Jimi or Eric is either a fool or a liar and a rogue.

If it continues dirty until quite low levels, you have probably blown your speaker, sorry.

:lmao:

Clipping, by its nature, limits the amplitude (loudness) of the signal.  Once the input signal dies away enough so clipping no longer occurs, well ... clipping no longer occurs.  It would certainly be possible to extract the dynamic of the note before heavy compression and clipping/distortion then re-impose that dynamic after distortion (and may be an interesting idea to follow up) but I don't know of any gizmo that actually does that.

[akis]

Not much.
Definitely not a "compressed" one, nor long sustain or attack squashing.
"Clean" channel gain is *usually* set to an "average" guitar, played by an "average" guitar player, starts clipping around 6 or 7 on the volume control.
Why? : so a weak player/pickup/thin_strings still have a little extra gain available to compensate (7 to 10 ) while a loud player will still have clean sound up to, say, 5 .
That with a true Audio/Log volume pot, of course.
So in practice you can overdrive a Clean channel by 6 to 10dB, not much.

My son wanted 4 channels. The two clean channels should be allowed to overdrive, softly, based on the "gain" control. The two distortion channels should start from overdrive all the way up to hard distortion. By "soft overdrive" my son wants to be able to hear every note clearly, but does not like it when the "distortion" falls off and a clean tone then remains. For example you strum the low E, you hear two or three seconds worth of overdrive and another four or five seconds of cleaner tone. He expects the same "overdriven" tone to become progressively more quiet but without losing its tonal characteristics.

Therefore I will tell my son that he cannot have everything

[phatt]

How about You make it clear what He/You want to achieve?
Maybe What Amp is in use Now,, what guitar,, what style of music is going to be played THEN We can give more focused advice. :tu:

My guess is you just need to try a few pedals.

and yes,, please do tell him,, you can't have everything in one neat box. 8|
though,, I'm sure someone will soon invent an app for everything.  :lmao:
Phil.