Blend Box for Mooer E-Lady

Big Monk

Well-known member
I drew this up today:

1650904770334.png

I'm looking for a minimally invasive way to:

a.) Get unity Volume
b.) A simple tone control
c.) A blend control

Anyone have any critiques of this circuit? It was a fairly basic clean opamp boost section that replaces the "Buff" in a buff and blend that has an AMZ tone control patched in. The goal is to have the volume control and blend AFTER the output of the E-Lady to avoid overloading/overdriving the MN3207.
 

Big Monk

Well-known member
Interested in how this works out for you.

Not sure sure I have it implemented correctly. I mashed a few things together. I think the gain stage and tone control have to be on their own half of a dual opamp. I’m going to redraw today.
 

giovanni

Well-known member
If you plug your guitar straight in, you will get a tone loss because the input is not buffered and the pickups have to drive both the pedal and this circuit. Adding a simple buffer before the send would solve that.
 

giovanni

Well-known member
I’m also not sure the blend will do what you want it to do. It’s basically just a volume control now, there is no dry signal mixed into the output.
 

Big Monk

Well-known member
If you plug your guitar straight in, you will get a tone loss because the input is not buffered and the pickups have to drive both the pedal and this circuit. Adding a simple buffer before the send would solve that.
I’m also not sure the blend will do what you want it to do. It’s basically just a volume control now, there is no dry signal mixed into the output.

I think I need a simple gain stage out front, reorganize Input/Send to add a dry signal into the blend, and use the other half of the opamp for the tone control.
 

Big Monk

Well-known member
Second attempt:

Eclectic Sidecar.PNG

9vDC Out is a courtesy/utility out so that I don't need to use an extra tap to power the looper/blender and the E-Lady. Moved the Send after the clean boost stage. Since I'm only trying to get unity gain for the E-Lady, I expanded the gain range slightly for the booster to a max of 15 dB just to compensate for the tone control section. I don't think I'll need anywhere near that but, better to have more range than less.

Tone control stage is straight from Jack Orman and the AMZ site:


Send is before the Tone control and the Tone control feeds the Blend portion of a Buff and Blend circuit.
 
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Feral Feline

Well-known member
What about taking a look at the Phantom Pain circuit?


It's based on the EQD Disaster Transport Sr, when stripped of its delay it can do 3 signals (ABC) blended, with A&B being parallel and fed into C. PCBGM copied the idea, calls it "The Blender", if you want to see a schematic (it's running two TL074s!).

Anyway, I'm suggesting taking a look at the Phantom Pain 'cause I thought maybe your schematic above could use a buffer/gain stage on the return. Add another to the send. Then everything is got its own buffer/line-driver. A couple TL072s to keep cross-talk down or maybe it all works on a single TL074...
 

Big Monk

Well-known member
What about taking a look at the Phantom Pain circuit?


It's based on the EQD Disaster Transport Sr, when stripped of its delay it can do 3 signals (ABC) blended, with A&B being parallel and fed into C. PCBGM copied the idea, calls it "The Blender", if you want to see a schematic (it's running two TL074s!).

Anyway, I'm suggesting taking a look at the Phantom Pain 'cause I thought maybe your schematic above could use a buffer/gain stage on the return. Add another to the send. Then everything is got its own buffer/line-driver. A couple TL072s to keep cross-talk down or maybe it all works on a single TL074...

I’ll check it out!

Really though, I’m looking for a very small footprint and a tone control as well.

I redrew for post #8.
 

Big Monk

Well-known member
I was referring to post #8 in my post #9... 😜

Legit question because while my comfort zone is high with transistor based circuits, opamps still throw me a loop: Why would I want to buffer the return? Also, why the send if I already have the booster stage up front that has a pretty high input impedance (i.e. working technically as a buffer)?
 

giovanni

Well-known member
A buffer is all about having a low output impedance. Your boost above has a relatively high output impedance. And you may want to buffer the return because depending on what you have in the loop, it may load the circuit if you don’t buffer the return and cause tone loss (many fuzzes would do that).
 

Feral Feline

Well-known member
I'm just regurgitating what I've seen been done elsewhere.

Think of a glass of beer, if you pour half its contents into another glass you need to top up both glasses or customers are going to be thirsty and angry.

Screen Shot 2022-04-27 at 04.59.56.png

So the beer above gets split and then both glasses get topped up. Everything gets topped up every time the beer is potentially diminished in any way.

Dang, I just saw Giovanni's post. Yeah, what Giovanni said...
 

music6000

Well-known member
I'm just regurgitating what I've seen been done elsewhere.

Think of a glass of beer, if you pour half its contents into another glass you need to top up both glasses or customers are going to be thirsty and angry.

View attachment 25703

So the beer above gets split and then both glasses get topped up. Everything gets topped up every time the beer is potentially diminished in any way.

Dang, I just saw Giovanni's post. Yeah, what Giovanni said...
Does it depend if your Glasses are Half Full or Half Empty???? :D
 

Feral Feline

Well-known member
Well if the glass is half empty, then I've already drank some, and still have some more left...
So, I'm an optimist half empty is good.

Doesn't matter, I don't wear glasses, I wear contacts.
 

thewintersoldier

Well-known member
Derek, since you know how to design and and fab boards, why not just take an existing schematic and add a blend control? I would think that would be much more gratifying rather than what you are trying to do above, which seems much more complicated and not the best approach to what you seek.
 

Big Monk

Well-known member
Derek, since you know how to design and and fab boards, why not just take an existing schematic and add a blend control? I would think that would be much more gratifying rather than what you are trying to do above, which seems much more complicated and not the best approach to what you seek.

It does start to get much more involved now than when I thought it up. I love the E-Lady, i just thought I had a down and dirty solution to add some more flexibility to it.

I've had my eye on the Past FX Elastic Mattress as a permanent flanger addition and I'm not opposed to that idea even now.

I've gone deep on the Mistress schematics now and your idea makes a ton of sense now that my simple boost/tone box has turned into a quadruple buffer behemoth!
 

Big Monk

Well-known member
I'm just regurgitating what I've seen been done elsewhere.

Think of a glass of beer, if you pour half its contents into another glass you need to top up both glasses or customers are going to be thirsty and angry.

View attachment 25703

So the beer above gets split and then both glasses get topped up. Everything gets topped up every time the beer is potentially diminished in any way.

Dang, I just saw Giovanni's post. Yeah, what Giovanni said...

@Feral Feline and @giovanni

Thanks dudes, but this got way out of hand!

I think what @thewintersoldier said is spot on: If I'm gonna have to draw up a board anyway, might as well just make it a tweaked Mistress.
 
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