Hydratone convolution EQ.

[Torben]

FFT convolution which makes MP3 quality out of the signal.

I would be very interested if you could expand on that.. I was under the impression that fft was just faster to calculate for long impulses, I didn't realise there was any difference in the result..?

No, there are compromises you have to make. Though you can get a very good sound from a MP3 file (which works just this way) there are losses. As a designer you have to decide if the good side of using FFT convolution (less CPU) are more important than the losses (bad pulse response, curtains around spectral components etc). In the case of a real space I would choose FFT convolution while I would use normal time bases convolution for speaker / cab responses, EQ's etc.

The next point would be to accept that the infinite impulses should be truncated into finite impulses in order to be convoluted at all.

Torben

[Torben]

Please ignore!

[Frippertronix]

Frippertronix,

While HydraTone don't recreate THD, it has an overall "warm" sound nontheless. Most of the "sound of an EQ" come from frequency/phase response. THD is quite a subble thing that, sometime is good, sometimes isn't.

Salvator

So the warmth we hear in Hydratone and '62 Valvetone is modelled and not derived from IR's?

I'm still confused on this issue. What is being conveyed by the IR of the old analog EQ's if not their signature sound, which would be described by most as "warm"? If no "valve tone" (which would be described by many if not most people as "warm") is being conveyed by an IR in the '62 Valvetone plug, then what exactly is being generated by the impulse response?

Are you saying that the "valve tone" of '62
Valvetone (which I definitely agree is there) is not coming from a captured IR of the Grommes EQ, but is in fact coming from an algorithmic model instead? If so, what is the purpose of the IR?

Does that necessarily also go for the tube mics included with my Gigastudio 3 convolution engine (GigaPulse)?

[JeffSanders]

I've loaded some speaker impulses into PSLight and SIR that definitely added huge doses of warmth into a track. No doubt about it.
Maybe not "distortion" warmth, but some weight.

[Frippertronix]

Yea, I think we're going to have to get technical about exactly what is meant by "warmth" in Engineerspeak...

I'm also curious about why a distorted sound will not capture/translate into an IR/convolution.

[Lesha]

I'm also curious about why a distorted sound will not capture/translate into an IR/convolution.

you answered the question yourself..

[bmanic]

I've loaded some speaker impulses into PSLight and SIR that definitely added huge doses of warmth into a track. No doubt about it.

This probably just comes from the frequency curve or 'sense of space' an impulse might have as no distortion can possibly come trough using simple convolution. Think of it like this:

A lot of people consider the "loudness" button (aka smiley curve EQ on home stereos) to make everything sound warmer. That's what you get, a simple different frequency curve.

-bManic

[Frippertronix]

I'm also curious about why a distorted sound will not capture/translate into an IR/convolution.

you answered the question yourself..

Where? What answer did I give?

[bmanic]

I'm also curious about why a distorted sound will not capture/translate into an IR/convolution.

you answered the question yourself..

Where? What answer did I give?

DISTORTION, or OVERDIRVE is IMPOSSIBLE with static impulse.

Warmth = harmonic distortion = impossible.

- bManic

[Frippertronix]

Hi all,


If a distorted impulse it used, it won't recreate distortion. Rather this will translate in a a weird non unspected frequency response.

.

I'm not an engineer, but if possible, a short technical explanation of why this is the case would be of interest to me.

[Frippertronix]

I'm also curious about why a distorted sound will not capture/translate into an IR/convolution.

you answered the question yourself..

Where? What answer did I give?

DISTORTION, or OVERDIRVE is IMPOSSIBLE with static impulse.

Warmth = harmonic distortion = impossible.

- bManic

ALL CAPS=yelling=unnecessary.

[Frippertronix]

I'm still intersted in Salvator stating, if he's willing, as to whether modelling was used in '62 Valvetone. If not, then somehow the impossible was achieved---i.e. some sense of "warmth" (whatever that means) through an IR.

If modelling was used, and the warmth is what people mostly like about Tritone's plugs, then I'm curious to know what was achieved by sampling hardware and using convolution.

One thing to keep in mind is that we have two mindsets in play right now: the musician mindset which doesn't care much about THD, etc., but only cares how things sound. If a certain frequency signature (emphasis, what have you) or spacialization sounds "warmer", then warmth is achieved, with or without THD.

The other mindset is the technical mindset that's defining warmth purely as dynamic and being equal to THD and nothing else.

Whichever way it is in this case deosn't really matter to me, since the end product of sound is all I'm concerned about, but it's helpful to shed some light on exactly what is going on in something like the Tritone line, since people, including myself, find them so useful.

[Frippertronix]

Having thought about this more, I've realized what my problem is with the argument that no distortion is present in impulse responses---if a signal was passed through an amplifier to capture an impulse response, was there no HD present in the ouput when the response was captured?

Salvator stated that distortion will produce very strange results when used in convolution, but certainly a tube amp from 1962 is going to have slight distortion/clipping present at clean settings because I doubt it is very linear, which is part of the reason why the real thing sounds good. So what about the slight harmonic distortion present in the original output signal, even when the unit was measured at a "clean" setting? Isn't that somehow incorporated into the convolution, and, if so, why doesn't it cause problems?

[Salvator]

Hi flippertronix,

to resume : The "warm" people hear in our plug comes from eq curve (frequency/phase response).
This is captured/recreated by the IR/convolution combo fairly accurately.
In fact, in our statics A/B tests with hardware EQ, it provided damn results.

Distortion can't be recreated by linear convolution simply because this is a dynamic effect. But distortion is very little part of the sound for EQ. Quite negligeable for most device and don't mean 'better' either.
Keep in mind that for eq, THD is generally under 0.1 %, even for coloured device (Massive passive, API etc..).

About distortion and weird response : I mean HEAVY distortion like clipping or even GTR amp for example. Where the timbral change very fast. It can sound interesting, but won't necessary provide the "expected" results...
Clipping is a obvious example of the effect i am talking about. It change the ratio/coherence between the coeficients (for example : the main coeficient - the spike of the IR- can be lowered while the rest of the IR remain untouched), thus change the response quite drastically.

Torben said :

The next point would be to accept that the infinite impulses should be truncated into finite impulses in order to be convoluted at all.

This is very true, and the biggest limitation for good results : The lenght of the IR directly dictate the bass response (among other) and ... the CPU load on the other hand...

Hope this helps some,

Salvator

[bmanic]

DISTORTION, or OVERDIRVE is IMPOSSIBLE with static impulse.

Warmth = harmonic distortion = impossible.

- bManic

ALL CAPS=yelling=unnecessary.

SOMETIMES it HELPS people UNDERSTAND better.

Sorry, no offence was meant btw.!

Cheers!
bManic