I put working samples.

http://amtelectronics.com/support/articles/why_tube-like_cannot_measure_up_to_tube_inside/
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.sugardas.lt%2F~igoramps%2Farticle68%2Farticle.htm&sl=ru&tl=en
Samples:
Real Mesa Rectifier:Pure-1.mp3
AMT R1:Pure-2.mp3

Thanks Findeton,

But can it be done without this many components, or with discrete components, and how can we increase input impedance since there is no 100Meg resistor?

here is the spice simulation of Fetron/Triodizer:
TrioFetron
Is there any thing I can improve with this design?

Quote from: Findeton on March 23, 2010, 11:38:28 AM
I think those things are called transistors... What we want is not 12AX7 replacements with more gain,but to emulate the distortion that tubes give (and it looks like the Tone Grinder/FETRON) doesn't give that.

I'm only sayin we can incorporate triodizer and cascode and your tremendous knowlege and make real SS 12AX7, with the same characteristics and more reliability.Tone Grinder has samples on website, hear to them(they sound almost identical to the real thing).Do you think maybe they use deplatation mode HV MOSFET's and sell them like that?(I doubt that, cause MOSFET's will sound dark and cold due to high input capacitance)

We can make high voltage SS tube replacement, by using cascode. high voltage mosfet will be used as a voltage regulator from the HV supply, to a safe level 24V(actually 20V, since mosfet will use 2-4V to conduct),and do the heavy lifting(amplifying the gain):
SS 12AX7.pdf
The gain of this device is very high(in my example,around 570!!!),the gain is around 570 with mathematical approach.(gm is 5.5679 mS(Av= gm x Rl = 5.5679mS x 100K = 567.9 = 55.7dB).
The input capacitance is very low, less than 2pF(due to cascode connection which reduces the input capacitane,and rounds up the clipped signal),identical to 12AX7.With nicely set feedback, we can outperform the real thing,with ss devices, and what is the best, NO MICROPHONICS, NO MORE HEATER TO CATHODE ELECTRON EMISSION, WHICH CAUSES HUM, NO MORE CHANGING TUBES...
Tone Grinder,aka FETRON
Tone Grinder is probably old FETRON, in nowdays production.I doubt it has characteristics of a real 12AX7, more likely version that I posted.

Quote from: soundroi on February 05, 2010, 07:56:48 AM
Hey! Another couple of questions for the experts, help needed!

1/ Well, my RG100 Classic haas really high gain, no need to use a Booster. But with ALL other amps I'm using a booster before the amp (and a Parametric EQ) to have infinite gain and that chainsaw metal tone. Is there any difference in them in this point, I mean, input gain?

2/ My RG100HT (blue rack unit) has an extreme hum noise problem, which I've seen is a common problem in this model if using high-gain settings. Is there any way to solve this? At his moment, and usin gain at 10 as I do, it is really hard to play it.

Thanks..

Q1 is hard to answer without the thing in front of me, too
Q2 isn't ground loop problem, cause RG100HT is RG100ES in rack unit(so it has it's own amplifier), the problem are main filter caps that are old and need replacement,that amp is very old, so the caps must be changed.Hum is present cause you have a large ripple current in the PSU, cause filter caps have done theirs.Problem is not in the preamp, cause it is 100% JFET design(2N5484 are low noise/microphonic amplifiers).

1.Do it like that, you will fry those heads.THESE HEADS CAN'T OPERATE WITHOUT LOAD!!!YOU MUST HAVE CABS ON THEM!!!!SERIOUS
2.That direct out is very hot, cause it serves for larger PA's.If it clips your powered mixer, probably the direct out pot isn't working properly.
3.Only way you can operate them as preamps, is to unhook the PSU for poweramp, so the only thing working in the circuit is the preamp, and you hook it to mesa or whatever via effect send jack.

Thanks,
The poweramp is my design with TDA7294(minor difference with datasheet's schem).Again the head has "LARGE" volume drop with diode clipping engaged(limit's the signal 0.7VAC p-p).

Peavey Windsor is a 100W tube amp and it can easily put out 100W in 16 or 8 or 4Ohm cab, on back panel there's a impedance selector, and with it you determine the output impedance of the amp.

I used NPN transistors (like Mesa did now on MarkV), but which power supply(30V) I should use, dual or single power supply for the gyrators?
And are the Q-point resistors fine,how can I determine them?
This my version of GEQ:

Hi guys,
I'll try to replace mesa inductors with gyrators, but I need some help:
1.Is the transistor emitter bias resistor fine(6.8K), or I should use another value?
2.Do I need to use dual voltage supply for the circuit?



Thanks

I made that amp a few years ago and it's awesome.
Here are my samples:
http://www.esnips.com/doc/d6a08723-1fef-4ab9-afd4-f8520f273388/Randall-RG100ES-Boost-1
http://www.esnips.com/doc/489be47f-e102-49d0-aac5-b09ee8a4870b/Randall-RG100ES-Boost-2---Scooped-Mids
http://www.esnips.com/doc/619f7c75-6446-4b4c-85d6-6bd8258b2137/Randall-RG100ES-Boost-1(Solo)

1.Yes the red channel is the distortion channel
2.Caps are in micro farads (10uF on the source of Q6)
3.Yes they are 4V Zener diodes,(1N914 are clipping diodes,or boost in that amp, but they attenuate the signal a lot).

Quote from: dsmnoisemaker on August 31, 2009, 10:06:07 PM
i couldn´t find a difference between the MG50DFX and the MG100DFX schems you posted..
i don´t think that the MG100DFX uses only 1 TDA2394..maybe 2 in BTL mode?

by the way i noticed that the power capacitors were only 1000uF?? isn´t that too small?

The difference between MG50/100 are in power supply (smaller mains transformer, couple of volts lower supply on MG50).
1000uF caps are correct values, thats a neat trick to emulate sag effect of tube power output.

I didn't, take the guts, but I will tomorrow when I'm finished with work