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Author Topic: cabinet simulator  (Read 7222 times)

kikey

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cabinet simulator
« on: November 27, 2009, 07:45:10 AM »
Hi

I have been testing a few cabinet simulators inspired by:

http://www.herby.kielce.pl/~piter/hexenew2/ie.php?c=cabsims_e&l=diy_e
http://home3.netcarrier.com/~lxh2/

I would also like to add a simulated high impedance output from the driving amp.
I suppose this could be done by adding a notch filter to simulated the impedance curve of the speaker.

Have you guys any experience with these circuits?




phatt

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Re: cabinet simulator
« Reply #1 on: December 04, 2009, 11:08:55 PM »
Hi kikey,
            They are not a one hit wonder but yes with some thought they can help.
Look closely at the amount of CUT in Db those curves show.

One curve in one place *May not work* you often need multiple stages of EQ and you have to know where to insert them.

I've built 4 of the JTM simulator and sold them mainly to folks in recording situations.
JTM circuit Live they can be a pain to work with you need to insert them *After* distortion effects.

That unit worked well after my old Quadraverb when I was recording but I use a completely different circuit live.

If you are going live forget speaker impedence curves and all the fancy stuff you need to EQ.
If you need more info just ask.
Phil.

kikey

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Re: cabinet simulator
« Reply #2 on: December 05, 2009, 04:45:54 PM »
One curve in one place *May not work* you often need multiple stages of EQ and you have to know where to insert them.

I've built 4 of the JTM simulator and sold them mainly to folks in recording situations.
JTM circuit Live they can be a pain to work with you need to insert them *After* distortion effects.

Yes, you are right, you need several LP-filters to achieve good results.
I have tested the circuit below with very good results when using headphones.
I think for example the Vox amPlug suffers from a bad cabinet simulator.
phatt, in what situations do you get problems with these circuits?



phatt

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Re: cabinet simulator
« Reply #3 on: December 06, 2009, 10:05:22 AM »
Hello kikey,
              I guess it depends on what you are trying to achieve, what kind of music
hence tone you want and importantly ,,*What gear you are running it all through*.

My emphisis is on *Live playing* so your needs are bound to be different if you are wishing to record guitar, So I'll just speak of my live setup.
No doubt some of this may give you ideas for recording setups.

I have two main setups, One utilizes a tube poweramp the other is all SS.
I stay with the SS setup as I assume you wish to work with SS.

For SS I first plug through my (PhAbbTone box) >> then a (Dynamic Distortion Control)
>> Then through a HiFi Graphic EQ >> then whatever Amp I feel the need to use on the day.
Mainly a 30watt SS Laney KB with basic Treble and Bass for final tweak.
(Yes it's a keyboard amp of all things so squeaky clean, no fancy guitar tweaked circuitry in this one, which is what you want for this idea to work well.)

The *PhAbbTone* is my own idea and it dramatically improves all the amps I've ever
plugged into, (including my Valve gear).

Go here; http://www.ssguitar.com/index.php?topic=1136.0 

Down the bottom of that page is a graph, now have a look at the mid cut in Db,,,
Now compare the Db on the HeXe page. I doubt you will find any that produce a 35Db cut in the midrange frequency.

Remember all these cab sims are active whereas mine is a simple passive input tone stack.

If you want all mid fuzz just bypass the tone box and tweak the graphic.
if you want the more modern sound then PhAbbtone switched on.

The DDC is just a fancy name for a dist unit with a cab sim built in which is loosely based on a very old circuit from a *Nobels SST* headphone unit which has a cab sim built in so I just tweaked it for live use.
I've made it much more dynamic so as to reproduce the classic rattle that old tube amps get (even when they are clean). Any fuzz box can do full on distortion but much harder to reproduce all the in between rattles, so yeah Works a treat.

DDC On it's own it's kinda average without the Graphic or the Tone Box.
but add tone shaping *Before and After* the *Dist and CabSim* then it's a whole new world of tone.  8)
I kid you not,,,You are talking about a NIGHT AnD DAY Difference in sound/tone/dynamics 0:)

The Graphic is just a second hand old Tandy one about 30 years old.
you just drill the back to mount 6.5 guitar jacks and bypass the pathetic RCA's
BTW Don't use the Boss GE7 pedal for this, it's a dud.

So hopefully you can now see I'm trying to get folks to see the basic concept is
DEAD Simple.        **EQ,Distortion,EQ**.
You can put my phabbtone box in front of most distortion units (Pedal, Rack or Amp mounted) and a Graphic after it and get quite stunning results.

When I try to impart the simplicity of this to frustrated young players I'm quite sure
they think I'm nuts, but nail down some fundermental tone shapes and it becomes quite easy to grasp.

So generally speaking you need about 4 basic tone shapes.
 A Big fender tone is a big dip at 300/400Hz,, the bigger the dip the bigger it will sound. (The steeper the notch the better it sounds,, shallow dips don't sound covincing). Hence my PhAbbTone does killer fender tone.

British sound is more Mid high the classic Marshall mid Honk as some refer it.
Cutting everything above 3 to 4KHz.

Modern Higain rock is kinda tricky but I get that by dipping the mid at 400Hz (PhAbbTone) and cutting the 1KHz on the graphic, the shape is sorta like a fender twin tone shape *before* dist then a tweed tone shape *after* distortion.
A Brilliant combination sound,, I love it. <3)

Metal, pull down a lot of mid band and big bass boost at 100/200Hz.
You can pulloff the Mark Knopfler sweet stuff but the valve setup tends to work better for that.

If you think I'm the only crazy nut that thinks in this manner then have a read of this page. http://www.amptone.com/truesecretofamptone.htm
Sorry,, All text so make a coffee and absorb the pure simplicity,,not that hard,,no maths involved. :tu:

So in answer to your question;
"phatt, in what situations do you get problems with these circuits?"
On there own they only produce average results,, but in combination with a well thought out setup. Great idea.

Others will have other ideas and thoughts on all this and I have no doubt there are many roads will lead to the same end but I'm just stating my experience with all this and I've not spent a $fortune$ in the process.
I have access to more sounds than most top line gear but at a fraction of cost.

Have fun with it all,
Phil.

kikey

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Re: cabinet simulator
« Reply #4 on: December 07, 2009, 04:25:57 PM »
Hi Phil

Thanks for sharing your ideas and thoughts!
I agree 100%, EQs are the key to a better sound.  :tu:

The setup I am working on will look something like this:

EQ > DIST > EQ > OD > + > poweramp
                      v
                      + > cab sim > headphone amp/line out


I am very interested in your PhAbbTone-circuit.
It looks like a tweeked tone stack.
I am going to try it in my simulator.
Is the steep notch produced with the mid-control at min ?

I am very interested in your ideas about Fender/British/ModernHigain/Metal sound.
I have not seen these characteristics sorted out anywhere on the net.
It would be nice to have it all in a table on a webpage  :)
Your ideas seem correct, the notch should be able to give the clear and open fender sound.
For achieving the British sound I think it is a good idea to limit the bass response to minimize intermodulation effects.
This can be compensated for in the post EQ.

Regards
/Bjorn

kikey

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Re: cabinet simulator
« Reply #5 on: December 08, 2009, 06:08:45 AM »
Maybe this link will give input for people trying to simulate classic amps:
http://www.harmony-central.com/Guitar/guitar-amp-evolution.html

Brymus

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Re: cabinet simulator
« Reply #6 on: December 08, 2009, 05:04:22 PM »
I really liked that article  :tu:
Alot of useful info if you dont know what sound it is you are looking for.
I was a little shocked that he recommended hiring a "Korean" amp tech to build an amp for the reader instead of "asian" or a better word would have been "knowledgeable" or "skilled".
Had a caucasian made this statement he would have been dubbed a racist or accused of "stereotyping".
Again had a caucasian recommended hiring a "white" amp tech the word racist would have been used to describe the author.
It just amazes me that this type of double standard was allowed to fly at Harmony Central
in spite of how useful the info is.

J M Fahey

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Re: cabinet simulator
« Reply #7 on: December 08, 2009, 11:31:59 PM »
Hi Brymus.
I had originally the same feelings about that article when I read it some years ago, but on re-reading it i got the clear impression that it was written specially for a given group of Korean musicians, probably "on demand", meaning to answer  a specific question.
Although the writer mentioned at the beginning the word Asian to give it a slightly broader appeal, his mind (and tongue ... and ..... keyboard ..... ) constantly slip into what he mentally sees as his audience.
I guess he refers to an hypothetical Korean technician, to make them rely on local talent, instead of trying to get Soldano, Bogner or whichever famous technician they daydream of.

phatt

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Re: cabinet simulator
« Reply #8 on: December 09, 2009, 01:14:01 AM »
Maybe this link will give input for people trying to simulate classic amps:
http://www.harmony-central.com/Guitar/guitar-amp-evolution.html


Yes interesting but it does not impart a simple straight forward explanation of tone.

Mutiple gain stages sound like a free ticket to Mass Distortion. 0:)
when done without any understanding of the *TONE SHAPING* that Also has to happen for it to work successfully the end result is often an amp that is a flop.

When I ask Players how they like there Big Name, multi channel, hi gain rock monster rig the answer is mostly like this;
"I just ended up useing the clean channel and I use floor unit/pedals to get all the other sounds."

Take the early Peavy 5150 it's a joke as it has a 10Db noise penalty in the effect loop,,,and that is present even if you don't use the EFX loop. :duh

I Fixed A laney ???something 30 watt recently; The Hot channel had so much hiss and hum that it rendered that channel unuseable. And that was a brand new Amp. :duh

Some of the Amps I test in the shops now are a complete joke. And I'm Talking the Big Brands as well as the SEAsian/China import copys. :duh

Plugged my simple tone box into a rather *boring* HotRod De'ville a few weeks back,,,
*THEN* it did sound like a REAL fender!!! 0:)

My2Cents, Phil.

phatt

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Re: cabinet simulator
« Reply #9 on: December 09, 2009, 01:25:08 AM »
Hi Bjorn,
         Great to hear that someone benefits from all my years of frustration.
Learning to use a simulator put me way ahead of where I was heading and certainly helped to understand what goes on inside the world of electronic amplification.

Re the PhAbbTone, Yes the mid full OFF will deliver the deep notch.
I tend to use the mid at 9 o'clock as full off really bites into the bandwidth and starts
to rob the sound as a whole. If you have a *Parametric* tone circuit you can achieve a similar tone shape but IME my tone box is darn hard to beat.
 
Re your setup looks good,, maybe insert a graphic *After* the CabSim before the HPhone Amp. Don't be afraid of using 2 graphics ,,even one after the other.

Simulate some of the old valve circuits and plot the response curves.
At every point the curve alters by small or large amounts, depending on where you poke.(Sims make light work of it all)

It then stands to simple reason that to recreate Valve tone, tone shaping becomes *very* important. It's very hard to recreate the half wave clip of triodes but thankfully it's not that important. Power tube compression is what you want and thankfully that CAN be recreated with reasonable results.

My thoughts on Cab sim. well I've found that the Marshall shape after a distortion
unit is the most useful as you can get the fender’ish sound via preamp tone shaping
anyway.  You will hardly notice any missing extended range because the graphic will pull it back up if needed.

IME A good fender Valve amp cranked up will tend to loose treble anyway as do marshall’s it's just more noticeable in a Valve Marshall. (Different output tubes)
I'm speaking about the old circuits not the modern higain stuff which I'm afraid have
lost the plot. IMO most are just clangorous noise makers and a few are just plain
unusable.

If you want build 2 sim circuits and switch between them but out of all the guitar
players I've helped 9 out of 10 want the modern rock sound anyway which
has more marshall colour / flavour anyway.

The hardest part to overcome then becomes the distortion itself.
I built dozens of dist boxes using multitudes of different ideas but alas if only I could
see past my stumbling block *the tone IS part of the dist*.

Yes every tube screamer (TS9) circuit or similar has a high pass filter in front and low
pass after the diodes but trying to do it all with one opamp package is close to
impossible. The basic TS type ciruit is pretty close but just lacks the extra EQ or a
CabSim.
-----
IMPORTANT side note:
A TS9 into a good tube amp sounds ok but when used into SS amps they can leave you wanting. So with SS you need a cab sim after distortion as SS power stages usually have miles to much bandwidth so they tend to be very harsh.
Remember a valve powerstage also runs through a transformer and the Tr wipes off
a lot of high freq hash. (close to perfect setup) But with SS no such luck as all the hash is passed onto your speaker so unless you want to design your own transformer coupled SS poweramp it's back to cab sims and EQ and some tweaking.
-----

With my DDC I opted to use the same input setup as the original Nobels I just added an extra pot to aid in the touch response effect.
I think the mistake that is often made with these circuits is the assumption of having a
big high impeadence input, which is just copying a triode setup but a triode may have
200VDC to work from. OOps! sadly your little opamp often only works from a small DC
voltage. At 10 to 20VDC it's A big ask.
There are places to use high value resistors in low voltage circuitry,,this is NOT the
place.

Big input imp gives big bandwidth, allows bigger AC signal swing, all of which become
discarded so why make it hard when there is no need.
A 100k input is all you need here. Throw in a 1meg resistor and you get more of
everything, noise, potential feedback, harder to control the dynamic response of the
diode clipper,, So I opted to stay with original Nobels input setup.

If I need more crunch I just use a simple Fet booster pedal to make the input signal
bigger forcing the diodes to clip a little harder so the whole circuit responds much more like a real tube amp would.
Bear in mind I do own and use Valve Amps so I do know what's happening.

Well enough talk;  here is my DDC circuit to give you some ideas to work on.
The original circuit can be found on *Nobels* site *SST1* but you might have to dig for it as this is a very old unit now. It's rather complex as the SST1 came with chorus
and delay and multi input selector, I only wanted the dist section and the cab sim.
It came with a rather poor attempt at compression which was like most compressors was a dud. These things just kill any dynamic response and make any guitar sound like a processor. IMO, Great in a studio but destroy guitar signals.

I've noted some of the changes I made on my schemo.
Took me ages to back engineer this thing and build a new one as the original was stuffing up and hardly worked.
Later I got onto the internet and found the schematic actually existed.
Darn All that work and it was sitting on the net the whole time.

I should state one tecky nitpick; The output really needs a buffer stage
but I don't find it a problem in use and it also meant another opamp so I scapped it.
It will be sensitive to the impeadece of what it's plugged into, ideally it needs to look into a high imp.

Build my tone box and the DDC and the rest is cheap stuff and a few odd bits.
Cheers, Phil.

 

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