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Started by Findeton, February 16, 2010, 05:07:15 PM
Quote from: J M Fahey on February 17, 2010, 07:44:45 PMHi findleton.Sorry to say so, but I think you are over engineering this too much.Personal opinion, everybody can disagree, is that we want to get a certain *sound* here.Triodes are one way to go, yes.Emulating their transfer curves is *part* of the problem, there are a zillion other factors to consider, specially when they are driven *beyond* the linear, "polite" part of their curves.I'm sure what you are doing here will grant you a scolarship at any great University you wish, but it's a little over our heads.Maybe you should post it at some IEEE's convention, it will be met with much acclaim.Maybe I'm mistaken here, it just happens I am a Minimalist , I prefer to get 90% of a triode with 1 resistor rather than 95% with 19 Op Amps, but of course, I insist, I may be a backwards kind of guy.Good luck and excellent work.
Quote(so no one can say again "you just can't get a triode out of silicon technology" Tongue).
Quotethis design I'm doing would only make sense if it's implemented on an Integrated Circuit (a chip).
Quote from: phatt on February 18, 2010, 04:38:58 AMHello Findeton, I quote; "I have a jtm45 hand-made by myself, but i'd love to have a pedal that is able to get the classic tube distortion without having to mod my amplifier nor having to pump up the volume. There are many stompboxes out there, even some with tubes in them, but I like to do things by myself."So I'll take it That this is the AIM of Your exercise?
Quote from: phatt on February 18, 2010, 04:38:58 AMTake the classic Bassman/ Marshall swap as an example;Without changing anything (other that a rebias) change the 6L6/5881 to a EL34.This turns a mildly hot bassman into a monster compressed OD machine.
Quote from: phatt on February 18, 2010, 04:38:58 AM"""""Pentodes where invented to overcome the limitations of triodes."""The sound you hear from you JTM is **Output compression** and has very little to do with triodes. (though the PI may hold some secrets).Triodes can't do it With the aid of a transformer so what hope is there with only a triode?? :duh[...]Tube power stages are just big oversized, overweight, expensive *Compressors* 8|Darn problem is that by the time they compress well they are to darn loud,as you have noted.[...]
QuoteBut it looks like most of the desired tube distortion comes from the output power tubes and the rectifier tubes, am I right now?
Quote from: dimitri on March 02, 2010, 10:55:21 AMQuoteBut it looks like most of the desired tube distortion comes from the output power tubes and the rectifier tubes, am I right now?This is correct for the amplifiers with single/dual triode preamp - bluesFor the triple/quad triode high gain preamps - heavy metal this will have less pronounced effect.You forgot the loudspeaker specific tone, when loudspeaker is driven that hard that the spider loose it linearity and cone self-resonance modes are excited.
Quote from: dimitri on March 02, 2010, 10:55:21 AMHello Findeton,Let me thank you to push this further. What was explained in my article is soft 3/2 nonlinearity and published circuit is suited for "aural exciter"-like applications. To emulate hard triode nonlinearity in guitar amp you should take grid current into account. The decoupling cap from anode to the next stage grid is charging with grid current, and the average grid voltage becomes more negative, thus the output waveform becomes similar to half-wave rectifier. After overload decoupling cap discharges through the grid resistor. You don't need to have 19 opamps in the circuit, you need a couple of extra components per stage.
Quote from: HENK on March 22, 2010, 08:04:06 AMHejVery cool!Are there Sub´s for the AD815??Greets Thilo