[linux-audio-dev] [ann] unmatched - a LADSPA amp tone

[Tim Goetze]

Steve Harris wrote:

>On Fri, Oct 25, 2002 at 10:15:20 +0200, Tim Goetze wrote:
>> >Nope, that would be hard ;) I was thinking of having a second, hard
>> >clipping alg. and bringing that in for high ampltudes.
>> 
>> oh yes, please keep on bringing them on.
>
>OK, I have some pending (easy) improvements to the meters, then I'l get
>onto this.

:)

>> i put in a music-dsp shaper (archive credits patrice tarrabia 
>> and bram) after the inverter, and with some eq (hp basically) 
>> before entering the first valve, it sounds surprisingly good.
>> especially with the bridge pickup, the neck pickup is still a 
>> bit muddy.
>
>OK, time for a quick lesson - whats the difference between the pickups? My
>bass (cheapish active 4 string) has two sets, a single wide one and a pair
>slightly offset (they say duncan on them FWIW). There is a knob that, I
>think crossfades between them.

the neck, usually placed exactly where the second octave is on
an over-sized fretboard, has far less dominant harmonics than
the bridge. your bass probably is a fender 'precision' type.
usually the split pickup is in the 'neck' position, though it
is much closer to the bridge than on a guitar, because the
sound becomes too dull if you pick up too little harmonics i
guess.

>> * it doesn't noticeably prolong sustain.
>> * the attack phase is 'flat', compared to the ringing
>>   of the real thing.
>
>OK... could this be a property of the cliping? Or is it always there?

always. i think it might be because a real valve amp sort of
'spreads the excess power' by turning the wave into almost
square at this point, where the guitar signal carries a lot of 
energy. more of a limiter effect, right?

>> * the sound gets muddy and faint when you turn down the 
>>   volume at the instrument, instead of keeping loudness and 
>>   reducing distortion.
>
>This is another compression effect I suspect.

>I think that the compression effect in a guitar amp is much faster than
>what you get from a general purpose compressor. I think it is more like a
>slow acting saturation. My Valve rectifier plugin (valve_rect) was an

my thoughts, too.

>attempt to capture that, but I expect it needs adjusting, or rewriting.

i just tried it before the first valve and it does help a 
good deal to have a better attack [in fact i got carried 
away strumming a funk pattern, a first time for playing the
guitar through the box], but i'm slowly running out of cpu. 

i guess a real HP has to be added, too (the pre-eq is done in 
the mixer now) because the lower band still has too much shaping 
power over the sound (sort of an auto-wah effect, emphasizing
the 'flat attack' problem).

tim