some questions about building a cabinet simulator

[Thugpoet]

I want to build a cabinet simulator pedal but I also want to add a headphone and a CD INPUT circuits in it.
Shall I just combine these layouts together like parallel the simulator's out to headphone circuit's in.
What if the layouts have different watts like 1/2 and 1/4, is it possible to just combine them together?
Is there any existing layouts or schematics like this?

[liquids]

In the end mine looked a heck of a lot different than this generic schem, but it's got most of the concepts I used.  Speaker sim alone is not enough for most ears...you need a pre-amp sim too, which most forget, as most guitar amps have serious mid scoop and are never flat...flat EQ with guitar sounds like Pat Metheny, but muddier...

[jkokura]

Liquids, I'm following what you've done as best I can... I think I'm getting it!

How would you come up with the values for the R's and C's?

Jacob

[liquids]

Breadboarding, calculation, trial and error, etc 

[Thugpoet]

Thanks for help!
There're some points I could not catch up with you.I saw some ICs' circuits in the schematic and I wonder how many IC I need to ues?Just 1 TL1054?

[edvard]

Frequency = 1/(2*Pi*R*C)

Simple algebraic substitution applies to come up with different values.
To make things simpler, C should be in Microfarads (μf), R should be in Megohms.
Or there are a hundred "RC Filter Calculator" pages on the web, like this one: http://www.muzique.com/schem/filter.htm

For the most basic of cabinet simulations, I've gotten good results using a 2nd-order high-pass filter stage for rolling off the lows around 100-200 Hz and a sharper (3rd to 5th order) low-pass cutoff for the highs between 3000 - 5000 Hz, with a gentle scoop in the mids.
Different filters need to be thought out for things like open back vs. sealed cabs but the basic gist is right there.

There are a million more factors to consider and model, but I'll leave that to those more technically inclined.
...Like this guy -> http://home3.netcarrier.com/~lxh2/

[jkokura]

Frequency = 1/(2*Pi*R*C)

Simple algebraic substitution applies to come up with different values.
To make things simpler, C should be in Microfarads (μf), R should be in Megohms.
Or there are a hundred "RC Filter Calculator" pages on the web, like this one: http://www.muzique.com/schem/filter.htm

For the most basic of cabinet simulations, I've gotten good results using a 2nd-order high-pass filter stage for rolling off the lows around 100-200 Hz and a sharper (3rd to 5th order) low-pass cutoff for the highs between 3000 - 5000 Hz, with a gentle scoop in the mids.
Different filters need to be thought out for things like open back vs. sealed cabs but the basic gist is right there.

There are a million more factors to consider and model, but I'll leave that to those more technically inclined.
...Like this guy -> http://home3.netcarrier.com/~lxh2/

Like Greek to me unfortunately. Actually, that's not true - I understand Ancient Greek better than that! I almost failed Algebra in high school, but I could write a paper like nobody's business. Now I work with people and struggle to get the numbers. I'll try and follow and build it on the Breadboard...

Jacob

[liquids]

It's got a fairly steep learning curve (just takes time) but learning LT spice helps a lot.

[edvard]

...
Like Greek to me unfortunately. Actually, that's not true - I understand Ancient Greek better than that! I almost failed Algebra in high school, but I could write a paper like nobody's business. Now I work with people and struggle to get the numbers. I'll try and follow and build it on the Breadboard...

Jacob

The LXH2 design is a complete end-to-end preamp-to-cab sim, so it might be a bit much to take on at first (though I hear it's nice).
Check out some of the simpler arrangements found here, on Geofex, Runoffgroove and Generalguitargadgets.

Liquid's schematic looks like a good one to follow to add the extras you're looking for, but the cab sim can be whatever one you choose.

If you're interested in learning more about filter design, read up on Butterworth Filters, Low-Pass, and High-pass for some basic edumacation.
You can ignore the math for now and just get familiar with the circuit topologies, because you're going to see those all over the place.
Basically, 1 resistor and 1 capacitor can make a 1st-order filter.
For 2nd-order and higher, more resistors, more caps, different values and some judicious use of active circuitry (op-amps, discrete gyrators) get you there, but don't worry about that for now.

Have fun!

[liquids]

My end version was significantly different from what I posted...however, the core elements are there...preamp sim, direct out, cabinet simulation, mixer section, output stage...I did add some amplification of the guitar signal and a passive volume control...made the HPF switchable, the mid frequency switchable, and the active high end filtering controlable for some low/mid/high control...likewise added some sensible protection for headphones etc...it was not a simple project, lots of breadboard hours in that!  The good news is, it's usable straight off the breaboard!

Do make sure you have a NE5532 chip or better for the output driving headphones (output impedance lower than 1 ohm).  Lots of recources out there about cab sim, preamps, tone controls, and headphone amps...though rarely in the same place.

[jkokura]

...
Like Greek to me unfortunately. Actually, that's not true - I understand Ancient Greek better than that! I almost failed Algebra in high school, but I could write a paper like nobody's business. Now I work with people and struggle to get the numbers. I'll try and follow and build it on the Breadboard...

Jacob

The LXH2 design is a complete end-to-end preamp-to-cab sim, so it might be a bit much to take on at first (though I hear it's nice).
Check out some of the simpler arrangements found here, on Geofex, Runoffgroove and Generalguitargadgets.

Liquid's schematic looks like a good one to follow to add the extras you're looking for, but the cab sim can be whatever one you choose.

If you're interested in learning more about filter design, read up on Butterworth Filters, Low-Pass, and High-pass for some basic edumacation.
You can ignore the math for now and just get familiar with the circuit topologies, because you're going to see those all over the place.
Basically, 1 resistor and 1 capacitor can make a 1st-order filter.
For 2nd-order and higher, more resistors, more caps, different values and some judicious use of active circuitry (op-amps, discrete gyrators) get you there, but don't worry about that for now.

Have fun!

Thanks Ed, really great advice! I'll work on your suggestions. In the past couple years I've gotten more and more familiar with the topologies, like the idea of a resistor and capacitor filter - it's the math that I don't get. When it comes to building this in particular, I can see it being quite a helpful circuit, which is why I asked about the values. I guess I'm more used to working from an established set of part values, and then tweaking from there. Perhaps that's why I can never seem to get anything I want to design myself to work.

I'll keep trying and I will have fun.