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Messages - rodriki1

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Schematics and Layouts / Re: Phatt-stuffRevisited
« on: January 27, 2011, 10:47:00 PM »
thanks phil. your ideas inspires me too much...
it sounds like a good idea if you post some sound sample too...
if it is not too hard work to you!!

Schematics and Layouts / Re: Randall T2 schematic!
« on: June 14, 2010, 07:10:42 PM »

thanks all for the attention given here.

J M Fahey suggested the listening of pritchard amp, so i did that.
i gave a closer "look" (hear) at sword of satori.
really amazing job. i passed the eye over all his patents but never stopped
to really enjoy the sound of it.
so we can think that he is close enough?? i found that in my humble
opinion he sound like better than many tube amps.
Like someone said one idealized tube amp.

What makes me impressed is that VOCAL CHARACTER OF SOUND
I know there is some sort of filtering after and before like
i have discussed a lot with "phatt".
I can not understand yet, what makes the guitar "scream".
Besides the skill of the player...
Would be sag with bias shifting???
I will keep researching. As you said pritchard is still a
mistery too!


another question.

can i believe that there is in this earth a reliable
model for pentodes that could be used in spice????  :duh ;D

i mean with grid compression and so on??

The only "famous" SS amps I found comfortably happy in that no man´s land were LabSeries ones, which allow for a careful and independent tweaking of  distortion and compression and the excellent Pritchard amps, whose real schematics nobody knows. Of course the many patents can be read, but what's actually used is anybody's guess.
Another *very* good but mysterious amp is the Bluetone.
Most other SS amps can be excellent either side of the barrier, but not on both.

i can supose that you had your hands on a pritchard (expensive) amp???
those very complex circuits can really sound like a compressed pentode output????


Actually I don't think ther was a Carvin SX that used 4558s then. Ithink the first SXs were around 87 and MOSFET.

you are right thanks.  the year john murphy designed sx was 1983... and the article
was 1981. thanks

well Thanks for your answer.

that is the point. WHY there is this preference for the tube amp.


but my question is that amp they used in the test sounds to be carvin sx.


to make a story short,

sorry for bothering with this subject again.

but i must say i liked so much this article below:

and i do not understand why things like this are not well accepted.

but this not the point.

i would like to ask... the transistor amp might be the carvin SX series????
if it is true that it is a carvin, why the man behind the idea (john murphy) did not
used or suggested an equalization after the preamp (as he did in his article
about duty cycle modulation).


Schematics and Layouts / Re: phatt's Schemo Collection
« on: May 17, 2010, 08:13:32 PM »

some time ago i have done some experiments with the Idea of LXH2 site.

i have made the LOW VOLTAGE power AMP (as they stated, genuine power amp
distortion with low power) using op amps as preamp and
two El84 as pushpull output...

i live in small apartment and i still found it was too much sound
for a low power amp (i used a generic 12" speaker i found in a store here)...

besides that a made another amp based on the LM388 chip using
a preamp with two simple diodes for distortion (just like boss DS1,
MXR distortion,guv´nor and so on). I used 1n4148 diodes.

I decided to compare the sound of the two amps.
i was expecting to have a HUGE diference.
but for my surprise the simple SOLID STATE AMP  sounded quite
the same thing.
The El84 amp was more fat and bright...
but i think that the cost of the tube based circuit was very much higher.
considering that i wired the output transformer with my own hands, it was
too much work...
to make my sound test i used one mp3 player as the input of those two
amps (playing some guitar riffs) and recorded the samples of output....
I swear i could make a blind test using those amps and people
would very hardly capture the diference.

I ask my self if could tell from the results i got, that tube amp for lower voltage have a cheap sound???
Or that we can really get the sound that we want from solid state????


the amp from LXH2:

the sample of the amp with lm388

Schematics and Layouts / Re: phatt's Schemo Collection
« on: May 16, 2010, 05:20:41 PM »

thanks again for the ideas here.

I just think here in my country is very expensive to buy a famous tube amp.

I like to know that some of you are willing to share the ideas and impressions.

as you mentioned there is a video of Brian May showing (in his opinions) how vox sound
bad without treble booster...

very interesting

Schematics and Layouts / Re: phatt's Schemo Collection
« on: May 15, 2010, 09:52:13 PM »
Hi Phill,

Thanks for a refresh on your ideas here phill.

I am interested in asking you if you know a cheap circuit
for me to try in a way that i could "feel" the so called
tube compression...
sometimes i think i have some sort of problems with my ears!!!
after i did the presence control that is a cheaper version of
a cab sim... i think that 80% of the sound of the tube amp
is caused by filtering effect of output more the kind of wood
box (usually huge and expensive)...
the best stompboxes outthere uses cabsim...
Why people still keep believing that tube is so important???
besides it is not that cheap to make a real good vintage tube amp.

Is the inventor the same person as Mitch Margolis of Manley Labs fame? Would be quite interesting shift from $$$$ high-end tube audio HiFi products indeed.

thanks for answers. it sounds you are right. the same guy...
i still have been dreaming about some one like andrew barta able
able to show us creative alternatives for tubes...

Hi guys,

what do you think about this recent patent on pentode replacement????
do you think this could really show the behavior of pentode after phase splitter...
the author claims it can do even the grid conduction effect or compression..

unfortunatelly those patents are always surrounded by mistery. i say tha it is
because they never are together with some real sample.

thanks in advance.

Tubes and Hybrids / Re: A 19OpAmp-2FET approach to the Triode question
« on: March 23, 2010, 12:05:26 AM »
take a look at this. one amzing discussion about triode

it is in russian language what makes things little bit hard to understand.

Preamps and Effects / Re: PhAbb SS AmpDemo
« on: February 14, 2010, 06:03:33 PM »
as i said to you i found this thing very interesting.
It sounds very ingenuous but if we take attention to this article:

4KHz is the edge zone...
just where i found that marshall would be... very
helpfull article.

if you play this thing with earphone you will be surprised...

I am very convinced that equalization is the most important matter about
music now... i have kept my self long time very much worried (concentrated) about
harmonic distortion (even odd harmonics etc) and compression, soft clipping etc.
this thing is not so much the secret..

Almost the entire circuit is dedicated to equalization!!!!!!!

i found it very good that you have energy and interest to get some time of experimentation with the idea.

As i said before using a software that gives you the chance to use equalization,
will give  a very large idea of how important equalization is....

i will find some time to make experiences here too..

We are used to see thowsands of circuits around the web... but some of then have a special potencial not very much considered..

One of them is the "super tube" of ibanez that uses this aproach to get
mid range equalization (changing  edge etc) and some tube simulation from
PEAVEY (patented). The last has some kind of PRESENCE  control as you mentioned...

But as i said there is not much TALKING about this thing... very rarely
some body comes to really compare something to tubes...
For me there is not this thing anymore.. something like tube sound..
What exists is TUBE AMP SOUND.
And the most important feature of a tube amp is the low damping output...
the equalization curve caused by higher output impedance interacting wih the speaker and the type of speaker usually used.

As said before the aproach used in tube screamer for distortion
sounds horrible when you want simulation of tube amp (power amp section)...
usually we have non inverting op amp in conjunction with diodes to give distortion.
I recommend the INVERTING APROACH like JD-10 from morley or stephan moeller ideas...

Transistor amp usually are made for general purpose (with high damping)...
But we like the effect caused by low damping, wich is A PEAK IN 100HZ and after
a raising gain until it fall down into 4khz, just like the treble booster...
The low damping and the box with the speaker does that...

I can clearly hear the sound the 4x12 box today...
As if the guitar sound is inside a wood box...

sorry by my simple english... have to improve my skill with the language...
hope some have benefits  with this things...

Much of what i said may sound silly but give yourself a time to give a better
look of what we say here and find you own conclusions... maybe could be fun...

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