freestompboxes.org

hi,

pre:
I know, the amount of literature and the number of circuits are vast,
I'm aware of Bajaman's work, for example, with lots of amazing amp and cab "simulation" circuits -- analogue modelling, so to speak
and I'm aware of the "amp emulation" circuits collected and laid out on vero board at tagboardeffects / blogspot:
https://tagboardeffects.blogspot.com/se ... 0Emulation

but I'd like to get a clear recipe for someone who just wants to
get her/himself a guitar and a pedal, and get on playing... knowing that her/his room, apartment is not suitable at any rate for practicing using an amp...

no, I'm not simply talking about a practice amp...
I'm talking about making a "breaking into overdriven state" apm... a small amp, just an amplett....
perhaps consisting of one J-Fet...

I'd like to see a model of solution for the case:

there is a guitar, and there is a tube screamer...
and a person playing the guitar, having a PC and a headphone,

knowing that this is not a tube screamer sound producing set yet...
cause we need an amp and a cabinet... or a "combo"...
cause what makes* the sound is
the amp and its tubes, especially the first tube.... that can be beautifully overdriven...


Instead of using attenuators to swallow the energies of an AMP so that a still close to line level (0,750 V) signal with tubely distorted sound could be harvested,

we could just capture the tubely overdriven sound right where it happens?
after the first tube? right?


so the question is:
how can we construct a post-preamp "pre-amp +1" amplification stage,
where the beautiful distortion / overdrive effect could take place...?
after which the signal could be enjoyed fed to a soundcard, or a phone amp, or to a PA of any sort...?

I know that Bajaman, for example, is a specialist of distortion / cab "simulation" -- analogue modelling, if that's what ti is?
but all those simulation circuits are designed to produce the sound of known and loved amps...

I'm thinking something simple, which could be a basic "amp-entry stage",
where a tube screamer could do what it was designed to do, that is, overdrive an amplifier circuit...

hi,

I know, the amount of literature and the number of circuits are vast,
I'm aware of Bajaman's work, for example, with lots of amazing amp and cab "simulation" circuits -- analogue modelling, so to speak
and I'm aware of the "amp emulation" circuits collected and laid out on vero board at tagboardeffects / blogspot:
https://tagboardeffects.blogspot.com/se ... 0Emulation

but I'd like to get a recipe for someone who just wants to
get her/himself a guitar and a tube screamer, and start playing...

knowing that her/his room, apartment is not suitable at any rate for playing through an amp...

cause at this point, this is not a tube screamer sound producing set yet...
and we need an amp and a cabinet... or a "combo"...
cause that's where it happens, the tubely distortion, in the amp and at its first tube(?), that can be beautifully overdriven...

I'm not simply talking about a practice amp...
I'm talking about making a small amp, just an amplett....
perhaps consisting of just one J-Fet... which (as I imagine) would do what the pre circuit does in an amp, before the actual amplification stage in the "overdrive channel" (which I have zero knowledge of)

So, the question is:
instead of using attenuators to swallow the energies of an amp so that a still-close-to-line-level (0,750 V) signal with tubely distorted sound could be harvested,
couldn't we just capture the tubely overdriven sound right where it happens?
after the first tube? i.e. a J-FET?

.
.

First of all, where does a soundcard come into all of this?!

real life situation?
supposing that a scenario like this happens:
someone wants to get her/himself a guitar and a tube screamer, and start playing

or
someone who plays keyboards, for example, and is used to being able to get her/his output from a line level output jack,
and feed it to anywhere, be it a mixer or a sound recording device

in addition:
lots of these new musicians, for whose sake manufacturers tend to produce "jr" sized guitars and basses might begin with a digital multi-effect which has cab sims, amp sims...

oh, I'm talking about "bedroom musicians" ?
no, bedrooms are today's garages...

in any case:
I realized that tiny preamps with one J-FET do exist,
like: https://tagboardeffects.blogspot.com/20 ... llman.html

and it is already clear for me too that a J-FET can play the role of of a tube in solid-state context, so...

jeepe wrote: ↑12 Mar 2022, 16:10 cause at this point, this is not a tube screamer sound producing set yet...
and we need an amp and a cabinet... or a "combo"...
cause that's where it happens, the tubely distortion, in the amp and at its first tube(?), that can be beautifully overdriven...

Not so, in general most of the Distortion happens in later stages of Valve amps.
I urge you to do a lot more research because you need a lot more than one FET to recreate the overdrive effect of a hi gain rock guitar sound,,Glass or Sand.

jeepe wrote: ↑12 Mar 2022, 16:10 So, the question is:
instead of using attenuators to swallow the energies of an amp so that a still-close-to-line-level (0,750 V) signal with tubely distorted sound could be harvested,
couldn't we just capture the tubely overdriven sound right where it happens?
after the first tube? i.e. a J-FET?

Some of the multiFX unit might be your best option.
Contry to popular opinion you don't need to use valves to create a great guitar sound.
Great sound is the combination of many factors,, i.e. distortion is easy,, but System tone shaping is SUPER Critical to the outcome.
Maybe something like the old Rockman would likely deliver a reasonable sound shape for a line level output.
Phil.

thanks very much, Phil!

phatt wrote: ↑14 Mar 2022, 10:53 I urge you to do a lot more research because you need a lot more than one FET to recreate the overdrive effect of a hi gain rock guitar sound,,Glass or Sand.

of course, I had done lots of forum readings before I posted this,
but not enough, obviously, also... all those readings were under the influence of the assumption that
J-FETS are like tubes...

after I had posted this open question, I began to find answers in texts which I had very probably read before, too...
as if having my new glasses on

for example in this thread:
https://www.diystompboxes.com/smfforum/ ... #msg207458

R.G. says:
"JFETs are not tubes. "

also that "(4) The quest for JFET emulation of tubes says more about human psychology than it does about JFETs."

before him, MR COFFEE:
“GOOD EMULATION IS WORK.”
and:
“[…] another issue not being noted by many here searching to emulate the overdriven tube sound is that the frequency and time-constants used in a tube's Cathode bias circuit cannot be duplicated by putting the same values in the Source bias circuit of a JFET.”


And I also read this, finally (an article which would come up at each and every search):
Tube versus solid state: The truth behind tube distortion
http://www.tonestack.net/articles/guita ... state.html

and the author states no less than:
"The smooth tone comes from the topology (design) of the amplifier and not from the power tube distortion. "
which is in complete agreement with what you say...

this article is actually really enlightening:

"It's important not to cherry pick. For example, when a practice combo (a transistor amplifier) sounds awful then it is always 'blamed to the transistors'. However, the awful sound of a transistor amplifier is caused by the poor circuit design (mainly by the poor filters) and not the components themselves."

..
"This behaviour depends on the actual shape of the waveform - which depends on the filters before the clipping stage."
...
"Good distorted guitar sound is not connected directly to components or technologies (tubes, transistors, op amps...). It is about how the guitar signal is filtered before and after the distortion."



so, thank you for urging me to realize that my imagination of how this works -- the tube sound -- was based on a completely wrong and ultimately simplified model!

PS:
I will try the preamp of this amp first: Marshall 3005 -- https://tagboardeffects.blogspot.com/20 ... reamp.html


.
.

Good to know it has helped and obviously you have done a lot of reading.
I agree with what you found, I think of Amp Tone/Sound as a culmination of many factors. Glass or Sand, both work if you know what you are doing.
Yes there is just so much going on it takes a long time to understand the tricks of this trade.

OK try that 3005 circuit but I just had a quick look at the original Schematic and the output of that preamp and it looks like it has no buffer stage on the output so it will be very limited in output and also the tone controls won't work very well.
These are Hi Z tone circuits and they will suffer great loss even with a short interconnect cable.
They need a Hi Z buffer stage to work to full capacity.

You will likely still need more than that one preamp to pull off a decent sound into a sound card or similar.
You maybe better off resorting to Plugins that come with most DAWs these days.
But IMHO, you will learn more if you build gear.
Phil.