Sorry to put a downer on the theory, chaps, but the easiest way of getting a valve sound in a pedal is to use an Ibanez tube screamer...
It's too long ago since I last fixed one to remember the circuit layout, but it was about 5 or 6 transistors, just done with a sprinkle of fairy dust...
You would be suprised how many guitarists with a "supposed" valve sound used one to get that Fender Twin just distorting sound, cos the Fender twin couldn't do it reliably in a gigging situation, but stick a tube screamer in front and you were laughing!
So is this more psychoaccoustics?
It's too long ago since I last fixed one to remember the circuit layout, but it was about 5 or 6 transistors, just done with a sprinkle of fairy dust...
You would be suprised how many guitarists with a "supposed" valve sound used one to get that Fender Twin just distorting sound, cos the Fender twin couldn't do it reliably in a gigging situation, but stick a tube screamer in front and you were laughing!
So is this more psychoaccoustics?
Add a bit of bias
hugobross, you might llike to try a little bit of bias to the diodes on your cct. You would have to separate them and feed the signal to them via caps. Maybe only a microamp or so each, just enough to get them up and barely conducting rather than the signal swinging freely and then slamming into the clipping point suddenly.
Some analog ccts use a "curve shaper" where the signal pulls up against a resistor, and as it goes past a certain threshold a diode becomes forward biased and effectively adds another resistor in parallel, then higher and another diode starts to conduct etc. Something along these lines might be worth playing with. Somewhere I think I saw an oscillator cct that turned a triangular waveform into a reasonable approximation of a sinewave using this method. Here's something http://www.uni-bonn.de/~uzs159/diode_tutorial/
Do a search on "diode" and "breakpoint" for more.
GP.
hugobross, you might llike to try a little bit of bias to the diodes on your cct. You would have to separate them and feed the signal to them via caps. Maybe only a microamp or so each, just enough to get them up and barely conducting rather than the signal swinging freely and then slamming into the clipping point suddenly.
Some analog ccts use a "curve shaper" where the signal pulls up against a resistor, and as it goes past a certain threshold a diode becomes forward biased and effectively adds another resistor in parallel, then higher and another diode starts to conduct etc. Something along these lines might be worth playing with. Somewhere I think I saw an oscillator cct that turned a triangular waveform into a reasonable approximation of a sinewave using this method. Here's something http://www.uni-bonn.de/~uzs159/diode_tutorial/
Do a search on "diode" and "breakpoint" for more.
GP.
MRH, sorry this is a tangent, but I'm not sure that I agree that "Spice is Spice". I won't question whether all programs use the same engine, but I recently tried to model a simple circuit where I was looking at a very specific variable. I was duplicating the results of a paper I was reading, but could not get the same result as the author, also using a SPICE program.
I am also aware that Circuitmaker uses different models to the conventional SPICE data provided by component manufacturers (ie you cannot simply load manufacturers' data into Circuitmaker)so it does make me wonder if all SPICE programs are indeed using the same engine.
Cheers,
Pete
I am also aware that Circuitmaker uses different models to the conventional SPICE data provided by component manufacturers (ie you cannot simply load manufacturers' data into Circuitmaker)so it does make me wonder if all SPICE programs are indeed using the same engine.
Cheers,
Pete
Some links, Great ones!
Did some research.
First, In #6 issue 2002 of Elektor Elektronics Magazine there is a Tube box. It uses an OP-amp, 4 diodes, 2 LEDs and 5 resistors to simulate Tube clipping.
Elektor #6 2002 Contents.
Here is 3 Great Guitar Stuffed Links dealing with overdrive distotion for Tube Sound. All have Schematics.
GMarts Guitar Page, Very Nice Site!
HIFI John's GuitarPage with a Tube Box Schematic
A link with over 50 Schematics for Guitar Amp & Effects
The Search was done with this:
Google search for Simulations of Tube Clipping
If you Click that URL, you find a lot more interesting sites
on your subject.
Groman from Sweden
gromanswe
Did some research.
First, In #6 issue 2002 of Elektor Elektronics Magazine there is a Tube box. It uses an OP-amp, 4 diodes, 2 LEDs and 5 resistors to simulate Tube clipping.
Elektor #6 2002 Contents.
Here is 3 Great Guitar Stuffed Links dealing with overdrive distotion for Tube Sound. All have Schematics.
GMarts Guitar Page, Very Nice Site!
HIFI John's GuitarPage with a Tube Box Schematic
A link with over 50 Schematics for Guitar Amp & Effects
The Search was done with this:
Google search for Simulations of Tube Clipping
If you Click that URL, you find a lot more interesting sites
on your subject.
Groman from Sweden
gromanswe
Hey, thanks for the links and the information. I'll check it out soon, I've been a few days off, and I'm doing some experiments with my just finished amp (see other thread).
Yes indeed, in circuitmaker you have to do the input at yourself.
I'm only using those spice programs to check out wether the schematic will work or not, the details I'll check in practice.
But in my experiences, I've never had big troubles with this program, but I'm always bewared of getting wrong results.
best regards,
HB.
Yes indeed, in circuitmaker you have to do the input at yourself.
I'm only using those spice programs to check out wether the schematic will work or not, the details I'll check in practice.
But in my experiences, I've never had big troubles with this program, but I'm always bewared of getting wrong results.
best regards,
HB.
Just started using circuitmaker, student
I have made one circuitdrawing with circuitmaker.
It seems to be a very good tool.
With Symbols to just drag into circuit.
I have only problem with to get wire to start.
Have to be exact in how long I hold down the mouse click.
Many times I do not get those blue lnies, indicating
that a wire is coming.
Maybe I have to change my values in my Mouse settings?
What do you play with your electric guitar?
wonders
gromanswe
I have made one circuitdrawing with circuitmaker.
It seems to be a very good tool.
With Symbols to just drag into circuit.
I have only problem with to get wire to start.
Have to be exact in how long I hold down the mouse click.
Many times I do not get those blue lnies, indicating
that a wire is coming.
Maybe I have to change my values in my Mouse settings?
What do you play with your electric guitar?
wonders
gromanswe
you don't have to hold down the mouse button to wire the whole thing. You've got to click once on a component to start drawing the wire (=Starting point) and click on another component, now you've wired a connection between these two components.
I'm not playing the guitar, a friend of mine is. He plays some blues and rock on his Condor or Ibanez guitar.
HB.
hugobross
Somebody mentioned the Elektor magazine where they published an article about generating "tube distortion" using opamps and diodes. Elektor even published a circuit using a tube (ECC81 or 83 but I can't remember) running on very low anode voltage and OP - AMPs to achieve the typical soft clipping of tube amps. I didn't buy it but maybe somebody ot there did (it was in a German Eektor issue in spring 2002).
I once did some PSPICE simulations with diodes in the feedback part of a non-inverting OP-AMP. As already mentioned by someone else it is possible to make several soft "bends" in the transfer function to achieve something like the soft onsef of clipping. My simulations showed mainly third order THD with a little 5th order as would be expected by any soft and symmetrically clipping amplifier.
If you are interested I can supply details.
Kind Regards
Charles
Somebody mentioned the Elektor magazine where they published an article about generating "tube distortion" using opamps and diodes. Elektor even published a circuit using a tube (ECC81 or 83 but I can't remember) running on very low anode voltage and OP - AMPs to achieve the typical soft clipping of tube amps. I didn't buy it but maybe somebody ot there did (it was in a German Eektor issue in spring 2002).
I once did some PSPICE simulations with diodes in the feedback part of a non-inverting OP-AMP. As already mentioned by someone else it is possible to make several soft "bends" in the transfer function to achieve something like the soft onsef of clipping. My simulations showed mainly third order THD with a little 5th order as would be expected by any soft and symmetrically clipping amplifier.
If you are interested I can supply details.
Kind Regards
Charles
That is right phase_accurate.
That is a device using tubes, with adjustable
overdrive level.
Not for Guitar, but for getting distored "tubesound"
out of a Sound ListeningSystem.
I am SUBSCRIBER to this best Electronic Magazine in the World.
Have almost complete Issues from 1985-2002!!!!!!!!!!
This Tube-Clipper Circuit uses one ECC83 per
channel. Anod voltage is only 12 volts.
Tubes are surrounded with TL074 bufferts.
It should be in issue #8 or #7 2001 of Elektor
Or why not buy the Elektor CD-Rom for 2001?
With all circuit Schematics, Layout and description!
I have Swedish Elektor, Allt om Elektronik, that comes a month after.
Personally I do not like any distortion when listening,
but for a musician it can be different,
when he like to express himself.
gromanswe
http://www.geocities.com/gromanswe/
That is a device using tubes, with adjustable
overdrive level.
Not for Guitar, but for getting distored "tubesound"
out of a Sound ListeningSystem.
I am SUBSCRIBER to this best Electronic Magazine in the World.
Have almost complete Issues from 1985-2002!!!!!!!!!!
This Tube-Clipper Circuit uses one ECC83 per
channel. Anod voltage is only 12 volts.
Tubes are surrounded with TL074 bufferts.
It should be in issue #8 or #7 2001 of Elektor
Or why not buy the Elektor CD-Rom for 2001?
With all circuit Schematics, Layout and description!
I have Swedish Elektor, Allt om Elektronik, that comes a month after.
Personally I do not like any distortion when listening,
but for a musician it can be different,
when he like to express himself.
gromanswe
http://www.geocities.com/gromanswe/
hi gromanswe
I don't like to listen to distorted sound either (specially not when listening to recorded music) !
But this is of course different to live sound, particularly with electric guitars and basses.
The first reason to actually (and intentionally !) USE distortion is as a sound effect (seldom for bass). This can be either real harsh kind of distortion generated by an effect called "fuzz-box" (using a heavily nonlinear transfer function). The less harsh distortion is generated mainly by driving a tube amplifier into clipping. Since tube push-pull output stages tend to clip soft with mainly (but of course not only!) 3rd order harmonics this sound is less harsh (the spectrum of many natural instrument contains 3rd order harmonics as well). The typical "screaming" sound of blues guitar players is typical for this.
I think the Elektor circuit could be used for that purpose as well with some tweaking (I have actually seen it but can't remember all the details).
The second reason for using soft clipping is a question of economy: The output signal of guitars and basses is quite peaky. I.e. the attack is asking for a lot of power. If you have an amp that clips soft then this might save as much as 6 to 10dBs of headroom (and when playing live you'll NEVER have enough power, and then it's usually better to clip soft than hard) !! The screaming sound mentioned above is actually generated by the soft distortion AND this compression effect (longer sustain, more gain to achieve feedback ....).
I once had a glimpse at the schematic diagram of a Trace Elliott bass combo that was using two zeners in the feedback part to achieve some sort of soft clipping. Because you don't usually let the whole band play through such an instrument amplifier you don't get that much IMD as you would get when running your CDs or whatever through such any amp driven into clipping.
I personally (I'm playing the bass guitar) like the sound as natural and uncompressed as possible and use a tube/SS preamp followed by a P.A. poweramp with enough headroom. Even the limiter (I.e. a device using a VCA, which is the other usual tool used for economy of power) is seldom used. On recorded music I prefer the sound of directly fed basses as well. But this is simply a matter of taste of course. If anybody likes to know how clean a directly fed bass guitar can sound shall listen to "A show of hands" by Victor Wooten.
Regards
Charles
I don't like to listen to distorted sound either (specially not when listening to recorded music) !
But this is of course different to live sound, particularly with electric guitars and basses.
The first reason to actually (and intentionally !) USE distortion is as a sound effect (seldom for bass). This can be either real harsh kind of distortion generated by an effect called "fuzz-box" (using a heavily nonlinear transfer function). The less harsh distortion is generated mainly by driving a tube amplifier into clipping. Since tube push-pull output stages tend to clip soft with mainly (but of course not only!) 3rd order harmonics this sound is less harsh (the spectrum of many natural instrument contains 3rd order harmonics as well). The typical "screaming" sound of blues guitar players is typical for this.
I think the Elektor circuit could be used for that purpose as well with some tweaking (I have actually seen it but can't remember all the details).
The second reason for using soft clipping is a question of economy: The output signal of guitars and basses is quite peaky. I.e. the attack is asking for a lot of power. If you have an amp that clips soft then this might save as much as 6 to 10dBs of headroom (and when playing live you'll NEVER have enough power, and then it's usually better to clip soft than hard) !! The screaming sound mentioned above is actually generated by the soft distortion AND this compression effect (longer sustain, more gain to achieve feedback ....).
I once had a glimpse at the schematic diagram of a Trace Elliott bass combo that was using two zeners in the feedback part to achieve some sort of soft clipping. Because you don't usually let the whole band play through such an instrument amplifier you don't get that much IMD as you would get when running your CDs or whatever through such any amp driven into clipping.
I personally (I'm playing the bass guitar) like the sound as natural and uncompressed as possible and use a tube/SS preamp followed by a P.A. poweramp with enough headroom. Even the limiter (I.e. a device using a VCA, which is the other usual tool used for economy of power) is seldom used. On recorded music I prefer the sound of directly fed basses as well. But this is simply a matter of taste of course. If anybody likes to know how clean a directly fed bass guitar can sound shall listen to "A show of hands" by Victor Wooten.
Regards
Charles
Thanks, I am no instrumentalist.
But Thanks for explaning the details.
The same as you told is in that LINK
I supplied in my post above.
GMARTS!!!
On distortion and overdrive
and different classical el-guitar-amps different carateristics
in their sound.
Really, if you do not go to that website,
YOU SURELY HAVE MISSED SOMETHING!
The receiver of musical sounds
gromanswe
But Thanks for explaning the details.
The same as you told is in that LINK
I supplied in my post above.
GMARTS!!!
On distortion and overdrive
and different classical el-guitar-amps different carateristics
in their sound.
Really, if you do not go to that website,
YOU SURELY HAVE MISSED SOMETHING!
The receiver of musical sounds
gromanswe
hey thanks,
Charles,
yes I know about that magazine, it's even more known here in Belgium or in the Netherlands as "Elektuur" (originally it's a dutch magazine). I've read the article and it's very interesting. I'm also glad to hear something from somebody who plays the guitar himself.
Gromanswe,
I will check that link soon, but I'm a little bit "out of time right now", just repaired an old amp, I'm occupied with design my own one, doing the last modification on my own build "light-mixer", etc... And just got a call to fix a PA-mixer. It seems I will never have a break (some guys of you will recognize this
)
HB.
Charles,
yes I know about that magazine, it's even more known here in Belgium or in the Netherlands as "Elektuur" (originally it's a dutch magazine). I've read the article and it's very interesting. I'm also glad to hear something from somebody who plays the guitar himself.
Gromanswe,
I will check that link soon, but I'm a little bit "out of time right now", just repaired an old amp, I'm occupied with design my own one, doing the last modification on my own build "light-mixer", etc... And just got a call to fix a PA-mixer. It seems I will never have a break (some guys of you will recognize this
)HB.
Good explanation
I would like to thank PHASE ACCURATE for
the BEST explanation of why tube amps sound
LOUDER and better than transistor.
This is the simpler and the best description of tube amp effect
i found during years of readings on the web.
All the stuff about harmonics and clipping
sound complex and mistic compared to this explanation.
But i still think personally about getting
THAT tube amp effect the compression.
Someday somebody with special resources and specific knowledge will get tube amps distortion from transistor.
Thanks again. Lets keep trying.
I would like to thank PHASE ACCURATE for
the BEST explanation of why tube amps sound
LOUDER and better than transistor.
This is the simpler and the best description of tube amp effect
i found during years of readings on the web.
All the stuff about harmonics and clipping
sound complex and mistic compared to this explanation.
But i still think personally about getting
THAT tube amp effect the compression.
Someday somebody with special resources and specific knowledge will get tube amps distortion from transistor.
Thanks again. Lets keep trying.
SteveG said:
how do you then explain the Carver Challenge where transistor amps were successfully modded to sound like tube amps? In this particular case, some cheapo Carver amps ($700 a piece) sounded just like some expensive Conrad Johnson tube amps.
Leach on his site also has an article where a transistor amp is "equalized" into a tube amp and his test subjects couldn't realiably tell them apart.
There may be some truth to the tube amp legend. and some of it may be urban legend as well.
Hi tlf9999,
That is true, but involves undistorted reproduction. With a guitar amp we are talking about creating a sound by driving the equipment into distortion. The transfer function would involve heavy modification to the SS amp.
I'm also very familiar with Carvers product. My company was the Canadian factory warranty center.
My fav guitar amp is the Fender Twin Reverb. It can create such a wide range of sound, not just crunch as in a Marshall.
-Chris
That is true, but involves undistorted reproduction. With a guitar amp we are talking about creating a sound by driving the equipment into distortion. The transfer function would involve heavy modification to the SS amp.
I'm also very familiar with Carvers product. My company was the Canadian factory warranty center.
My fav guitar amp is the Fender Twin Reverb. It can create such a wide range of sound, not just crunch as in a Marshall.
-Chris
did anyone ever build that elektor tube box? is there any review? i build mine, look at TB1.PDF - 4shared.com - document sharing - download
elektor tube box
i did my own pcb, take a look Tube Box 1.pdf - 4shared.com - document sharing - download
i did my own pcb, take a look Tube Box 1.pdf - 4shared.com - document sharing - download
tube box doesn't sound good
finished my own tube box Tube Box 1.pdf - 4shared.com - document sharing - download based on elektor, but i don't think it's a good one. i will try sansamp classic from tech 21
finished my own tube box Tube Box 1.pdf - 4shared.com - document sharing - download based on elektor, but i don't think it's a good one. i will try sansamp classic from tech 21
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