Distortion pedal with Fender 5F6-A type EQ

[sffwy]

You're not showing the Electra, Sffwy.  This is the Electra.




Because it has clipping diodes, the output signal is going to be lower than one might expect. You could try sticking the tone stack after it with Muff recovery stage, as an experiment (which might have a lot of noise and leave a lot to be desired),

OR

Make the 2 transistor driver/recovery circuit that Antonis posted above, and put the tone stack inside it where it says "EQ", which is what I recommend.  If you are doing this on breadboard it shouldn't take much time to try it both ways, esp. since you'll want to build the Electra and the tone stack anyway. 


EDIT: Now I see you want to use the Muffer up front?  Same sort of deal.  What the others are saying is to use the last stage of the 'real' Big Muff Pi circuit to recover the level lost in the tone stack.  The 2 transistor circuit Antonis posted will do this fine - I would literally build what he presented and consider it all the 'tone stack', placing Electro or Muffer before it.

Thanks for the correction.
I think that is an image I added to the Electra folder by mistake.
The one I already created is definitely Electra.
I need to be more careful.


I hadn't considered the order Electra -> Muff -> Tone stack.
I will try it on a breadboard.
And it seems that what I really need to do is to make an effort and understand Antoni's schematics perfectly.


Thank you very much.

[antonis]

As Sir Mike(*) & Rob(**) said , output impedance (and signal amplitude) of Electra distortion (the original one.. ) is rather complicated (and variable..)

If you wish to implement it as distortion and EQ driver stage, it should be wise to place a buffer between them..
(actually, it always is a good idea to use a buffer for variable impedance configurations driving..)

(*) Hard clipping configuration..
(**) Feedback bias configuration..

P.S.
I do understand that there are many        factors to consider for such a "simple" circuit but that's the real world..

[GibsonGM]

I hadn't considered the order Electra -> Muff -> Tone stack.

Umm, I think the right order would be Electra OR Muffer >  Tone Stack  >  Recovery stage  and see if it does what you want

or

Electra OR muffer > Antonis' driver > Tone Stack > Antonis recovery, and I would choose this way.

Electra going into Muffer is likely to sound very much like ass. 

I say get the idea working, simply, and then if you want something more advanced, you can do that after.

[sffwy]

As Sir Mike(*) & Rob(**) said , output impedance (and signal amplitude) of Electra distortion (the original one.. ) is rather complicated (and variable..)

If you wish to implement it as distortion and EQ driver stage, it should be wise to place a buffer between them..
(actually, it always is a good idea to use a buffer for variable impedance configurations driving..)

(*) Hard clipping configuration..
(**) Feedback bias configuration..

P.S.
I do understand that there are many        factors to consider for such a "simple" circuit but that's the real world..

It seems that what I am trying to do is more complicated than I thought.

(actually, it always is a good idea to use a buffer for variable impedance configurations driving..)

I'll keep that in mind.


Let me ask you a few more questions.


What should I use for Q1 and Q2 in Antonis Driver & Recovery? Are there several options?
How long can a 9v battery run?

Does Bassman do the buffer at the arrow position in the image?




Thank you again and again..

[sffwy]

Umm, I think the right order would be Electra OR Muffer >  Tone Stack  >  Recovery stage  and see if it does what you want

or

Electra OR muffer > Antonis' driver > Tone Stack > Antonis recovery, and I would choose this way.

I want to put Electra first,

Electra -> Antonis' driver -> Tone Stack -> Antonis recovery

I think I will use.

I say get the idea working, simply, and then if you want something more advanced, you can do that after.

Thank you. I'll give it a try.

[antonis]

What should I use for Q1 and Q2 in Antonis Driver & Recovery?

Any general purpose n-p-n BJT amplifier..
(e.g. 2N3904, 2N5088/89, BC546-550, BC182-184, etc)

How long can a 9v battery run?

It strictly depends on circuit total carrent draw..
It's easy to calculate it but it's easier to measure it..
(just place a low value resistor in series with +9V battery terminal and measure the voltage drop across it, in case you don't wish to use your DMM in current measurement mode..)

Does Bassman do the buffer at the arrow position in the image?

Yes..
You can recognize it by the output of V2B (Cathode follower) and compare it with V2A output (Common cathode amplifier)..
V2B output is considered very low, compared with V2A one, so it can drive succeeding stage (EQ) much more easily than V2A..

In brief: V2A serves as voltage amplifier where V2B serves as current amplifier..

I now have a question for you: What is the product of voltage and current..??

[sffwy]

What should I use for Q1 and Q2 in Antonis Driver & Recovery?

Any general purpose n-p-n BJT amplifier..
(e.g. 2N3904, 2N5088/89, BC546-550, BC182-184, etc)

How long can a 9v battery run?

It strictly depends on circuit total carrent draw..
It's easy to calculate it but it's easier to measure it..
(just place a low value resistor in series with +9V battery terminal and measure the voltage drop across it, in case you don't wish to use your DMM in current measurement mode..)

Does Bassman do the buffer at the arrow position in the image?

Yes..
You can recognize it by the output of V2B (Cathode follower) and compare it with V2A output (Common cathode amplifier)..
V2B output is considered very low, compared with V2A one, so it can drive succeeding stage (EQ) much more easily than V2A..

In brief: V2A serves as voltage amplifier where V2B serves as current amplifier..

I now have a question for you: What is the product of voltage and current..??

I ordered the parts needed for Antonis Driver & Recovery.
(Please let me know if there is another suitable name for this circuit.)

Thank you so much.

[GibsonGM]

Did you make sure to order extra parts?  Say, 20 transistors and not just 2?  That's how one gets all the things needed to try out ideas on the fly 

Without a real engineering education (I am a DIY hobbyist, not pro), I believe the transistor stages are called 'boot-strapped common emitter gain stages", with a high input impedance and low output impedance.   Antonis (who enjoys math and solving transistor problems!) designed them with those characteristics in mind.  It is ok for us who are not engineers to save the images and use them...I did!  I saved that pic as "Antonis tone stack driver"      If I need to do what you are doing, I will go to my circuit collection and use this, since it was already designed!  No need to re-invent the wheel - unless you enjoy doing so. 

The stages should match what comes before them well (not load them), have enough gain to drive a tone stack without introducing noise, and then recover from the tone stack's insertion loss, matching it with following circuitry (a volume control....the next pedal... or what have you).    The layman's explanation is that the tone stack will LOAD prior circuitry and cause loss of high frequencies, noise, and degradation if we don't feed them a 'conditioned' signal, which this does.       

[sffwy]

Did you make sure to order extra parts?  Say, 20 transistors and not just 2?  That's how one gets all the things needed to try out ideas on the fly 
 

Thank you for asking.
I will always order 10 or more if they are inexpensive parts.
I don't want to pay $5 shipping every time.

Without a real engineering education (I am a DIY hobbyist, not pro), I believe the transistor stages are called 'boot-strapped common emitter gain stages", with a high input impedance and low output impedance.  Antonis (who enjoys math and solving transistor problems!) designed them with those characteristics in mind.  It is ok for us who are not engineers to save the images and use them...I did!  I saved that pic as "Antonis tone stack driver"    If I need to do what you are doing, I will go to my circuit collection and use this, since it was already designed!  No need to re-invent the wheel - unless you enjoy doing so. 
   

I'll call it that too.
I am waiting for Antonis permission.

The stages should match what comes before them well (not load them), have enough gain to drive a tone stack without introducing noise, and then recover from the tone stack's insertion loss, matching it with following circuitry (a volume control....the next pedal... or what have you).    The layman's explanation is that the tone stack will LOAD prior circuitry and cause loss of high frequencies, noise, and degradation if we don't feed them a 'conditioned' signal, which this does.     

To me this is a perfect explanation.

[GibsonGM]

Antonis will be fine with you using his design.  Almost all circuits are offshoots of what has already been 'invented', many directly from manufacturer's application notes!     

There is a lot more to research if you want to.  You can Google "tone stack insertion loss" and find out a lot.
"Impedance matching" is another.   Read up on buffers at the AMZ site linked at the top of the forum (a great resource, check out all his articles!).

Ultimately, we'd like to see a low output impedance 'driving' a high input impedance.  "Low" suggests it can 'source' a fair amount of power, and the high input won't draw much from it (that would be 'loading').   Most tone stacks are low input impedance, hence the need for this BUFFER (current amplifier) before it, which (usually...) does not provide voltage gain, but CAN source power (to drive a low input impedance load).   Buffers themselves have a high input impedance, so don't affect what comes before THEM.      What Antonis presented is 'boot strapped' (another term to look up), which improves the buffer's performance by feeding back some signal to the input, further preventing loading.    A lot to take in, but with some reading it will make sense.   

Impedance ("AC resistance") is denoted by "Z", this is what is referred to by "hi-z" or "lo-z" microphones and the like.

[sffwy]

Antonis will be fine with you using his design.  Almost all circuits are offshoots of what has already been 'invented', many directly from manufacturer's application notes!   

I was referring to the name "Antonis tone stack driver".
I will gladly use the circuit.

There is a lot more to research if you want to.  You can Google "tone stack insertion loss" and find out a lot.
"Impedance matching" is another.  Read up on buffers at the AMZ site linked at the top of the forum (a great resource, check out all his articles!).

Ultimately, we'd like to see a low output impedance 'driving' a high input impedance.  "Low" suggests it can 'source' a fair amount of power, and the high input won't draw much from it (that would be 'loading').  Most tone stacks are low input impedance, hence the need for this BUFFER (current amplifier) before it, which (usually...) does not provide voltage gain, but CAN source power (to drive a low input impedance load).  Buffers themselves have a high input impedance, so don't affect what comes before THEM.      What Antonis presented is 'boot strapped' (another term to look up), which improves the buffer's performance by feeding back some signal to the input, further preventing loading.    A lot to take in, but with some reading it will make sense. 

Impedance ("AC resistance") is denoted by "Z", this is what is referred to by "hi-z" or "lo-z" microphones and the like.

Thank you. I will definitely check it out.


This is not what I was going to do yet, but let me ask a question while there are people on this topic.

Sometimes in my environment I need to input directly through EQ and DI into the mixing console. (This happens only a few times a year, but it's a problem if I can't do it.)
The output from the full range speakers is fine for clean tones and saturation, but distortion is very unpleasant because you hear overtones that should be cut by electric guitar amp speakers.

So I used to carry EQ and filters that I didn't know if I would ever use.

My question is, can I add a low pass filter to the Antonis tone stack driver (recovery stage if possible)?

The cutoff frequency is fixed and 6db/oct is fine. (The filter I used was 18db/oct or higher, but as far as I can tell that seems difficult to do with a simple circuit).
If the recovery stage has a capacitor for the low pass filter, it would be very useful for me if I could switch the value between the original and the low pass filter.

If this feature would ruin the Antonis tone stack driver, then of course it is not necessary.

[GibsonGM]

To be honest, it sounds like your problem is the sound you get DI, correct?  Because you're going into a console, and the speakers are hi-fi.   If so, to overcome this, I suggest building a cab simulator box separate from any pedals you're making...the Dead Astronaut "Astro Sim" cab simulator is a very good one, and easy - get the PCB from Rob's site, it doesn't cost much at all.  The work - the filtering - is already done this way.

https://deadastronaut.wixsite.com/effects

You use this last in your signal chain and it is as if you mic'd a guitar cab- so is useful for ANY pedal.  I built one and it has many uses, and isn't limited to ONE pedal    Sometimes to play with headphones, sometimes after a tube preamp into my DAW, those applications.

[sffwy]

To be honest, it sounds like your problem is the sound you get DI, correct?  Because you're going into a console, and the speakers are hi-fi.  If so, to overcome this, I suggest building a cab simulator box separate from any pedals you're making...the Dead Astronaut "Astro Sim" cab simulator is a very good one, and easy - get the PCB from Rob's site, it doesn't cost much at all.  The work - the filtering - is already done this way.

https://deadastronaut.wixsite.com/effects

You use this last in your signal chain and it is as if you mic'd a guitar cab- so is useful for ANY pedal.  I built one and it has many uses, and isn't limited to ONE pedal   Sometimes to play with headphones, sometimes after a tube preamp into my DAW, those applications.

Thanks, I will look into ASTROSIM as well.

I have several cabinet simulators. For me it worked better if I took the time to set it up with an EQ and then run it through a filter.
Besides, since antonis designed it for me, I was hoping it would be complete on its own.
If this works out, it will be a lot easier since I won't need the 4u rack mount EQ and Moog 101.

[antonis]

I am waiting for Antonis permission.

Permission for what..?? 

Plz ignore everything called by Sir Mike (who is a very perplexing guy but we do love him a lot) "Antonis'" design  and, honestly, be my(our) guest for implementing whatever is discussed here..

[GibsonGM]

I DID say that most of these circuits are taken from the 'typical applications' that manufacturers release     And other places - they have been around for ages.  Like tube amp stages; nobody really owns them.  But since you took the time to draw it up, Antonis - I think it is ok to call it "Antonis's Driver"  ha ha.  At least if using the drawing, since that is your intellectual property!

Sffwy - Since the driver/recovery BJT stages are there to implement the tone stack...that is their job - that circuit block is complete.  To make this one pedal contain the filtering you describe would be far more complicated, and would be best done as a separate unit that can be used with many 'platforms', in my opinion     I say build it on breadboard, try it out, and work from there!     

[sffwy]

I DID say that most of these circuits are taken from the 'typical applications' that manufacturers release    And other places - they have been around for ages.  Like tube amp stages; nobody really owns them.  But since you took the time to draw it up, Antonis - I think it is ok to call it "Antonis's Driver"  ha ha.  At least if using the drawing, since that is your intellectual property!

Sffwy - Since the driver/recovery BJT stages are there to implement the tone stack...that is their job - that circuit block is complete.  To make this one pedal contain the filtering you describe would be far more complicated, and would be best done as a separate unit that can be used with many 'platforms', in my opinion    I say build it on breadboard, try it out, and work from there!     

If it's going to be complicated I should not do it.
I will follow your advice and try a separate unit.
Thank you.

[sffwy]

I am waiting for Antonis permission.

Permission for what..?? 

Plz ignore everything called by Sir Mike (who is a very perplexing guy but we do love him a lot) "Antonis'" design  and, honestly, be my(our) guest for implementing whatever is discussed here..

Sorry. I had missed your reply.

I was referring to the name "Antonis tone stack driver".

Now I am waiting for the parts to be delivered.

[antonis]

can I add a low pass filter to the Antonis tone stack driver (recovery stage if possible)?

You have 3 options:

1. Implement both Rx and Cx (the effective value of Cx is multiplied with Q2 stage gain plus unity - Miller effect)

2. Omit Cx and use Q2 C-B interelectrode capacitance instead (usually 4-5 pF)..
(not recommended due to Rx rather big value needed, hence noisy as hell..)

3. Omit Rx and use Q2 Base spreading resistance (usually 50 - 200 Ohms)
(also not recommended due to r_bb' value uncertainity..)

P.S.
I've build distortion pedals based on 2. & 3. options but their functionality was just a matter of luck..

[sffwy]

can I add a low pass filter to the Antonis tone stack driver (recovery stage if possible)?

You have 3 options:

1. Implement both Rx and Cx (the effective value of Cx is multiplied with Q2 stage gain plus unity - Miller effect)

2. Omit Cx and use Q2 C-B interelectrode capacitance instead (usually 4-5 pF)..
(not recommended due to Rx rather big value needed, hence noisy as hell..)

3. Omit Rx and use Q2 Base spreading resistance (usually 50 - 200 Ohms)
(also not recommended due to r_bb' value uncertainity..)

P.S.
I've build distortion pedals based on 2. & 3. options but their functionality was just a matter of luck..

Thank you so much.

My choice should be 1 of course.
I looked up Miller effect,

Miller input capacitance makes an RC low-pass filter with the internal resistance of the signal source.

If so, I thought the following calculator could be used. is Miller effect and Miller capacitance different?

https://www.muzique.com/schem/filter.htm
https://www.learningaboutelectronics.com/Articles/Bandpass-filter-calculator.php#answer1


I also looked into gain and unity.
I didn't understand it perfectly, but I tried to calculate the gain first,

https://stompboxelectronics.com/resources/common-emitter-amplifier-calculator/

Base-Emitter Voltage and Beta/hFE do I need to measure the transistors used with a multimeter?
If so, I don't have a multimeter and would have to order one.
It is highly possible that the calculations I am doing are meaningless to begin with.


Is there a guideline value for C? If so, it would be very helpful.

[antonis]

Is there a guideline value for C? If so, it would be very helpful.

It depends both on LPF cut-off frequency of your taste and EQ variable output impedance..
(so proceed to trial and error process..)

P.S.
May I ask the reason for LPF ..??