Blendable Klon-type Overdrive

[markm]

Build it, but like I suggested - in the loop of the splitter blend. It sound pretty cool.

I like the idea but, the splitter blend starts to head toward SparkleDrive territory and, well I've already been there.
That's alot of hardware to add just to balance out this circuit and leads to quite a large layout with 4 op-amps etc.....
I think if that's the only alternative to making it work well, I may not persue it any farther.
I appreciate your help here freddd, the info you have provided has been very useful indeed. Thanks! 
We'll see what happens from here.
One thing I will say that surprises me about this discussion is how many of the "big-guns" on the forum have not posted anything
regarding this circuit........maybe this is taboo territory, I'm not real sure.

[magikker]

If you want to get the big guns in on it post the schematic. Those guys are suckers for schematics. 

[John Lyons]

Just chiming in here to say that it looks pretty neat Mark!
I'm curious why you went with an op amp boost rather than a mosfet boost.
That would have fewer parts and then you could work out the blend circuit bits and save some real estate.

Maybe a schematic would help folks see what's going on here. Don't know where the circuit whiz folks are...

John

[markm]

If you want to get the big guns in on it post the schematic. Those guys are suckers for schematics. 

That's funny but, highly unlikely.

Just chiming in here to say that it looks pretty neat Mark!
I'm curious why you went with an op amp boost rather than a mosfet boost.
That would have fewer parts and then you could work out the blend circuit bits and save some real estate.

Thanks John!
I thought of just doubling-up the OD250 circuit and....well.....ummmm.... here it is!

Maybe a schematic would help folks see what's going on here. Don't know where the circuit whiz folks are...

I think I know where they are, avoiding this thread like the Plague!
They don't need to see a schem......I'm sure they know what an OD250 looks like by now and, the schem for said circuit can be found anywhere, I mean, WALMART probably sells it someplace! It's 2 of the exact same circuit, if anyone looks at the OD250 schem be it at Tonepad, GGG, here in the schem section, it's there.
I think perhaps I have come a little too close for "comfort" here for some and perhaps that's a good sign huh?! 

Of course, the other side of the coin is, Maybe, Just Maybe they are just as confused as I am as what to do with it so, they move on!

I'd like to make it clear that my intention is NOT to Clone the KLON but, to make a "work-a-like" circuit or similiar type circuit.
My favorite OD is the 250 so, that's part of the reason I chose it and, it's simple.....like me!!

[markm]

Schem for the OD250 can be found here;

http://www.montagar.com/~patj/dodoverd.gif

Many thanks.

[John Lyons]

Mark

The schematic for the OD250 is easy to get... My point was just that the buffer circuit and clean/OD combo workings would be more clear if they were in front of us as a post schematic. That way you can have a tangible reference to look at and work off. Kind of like the boogie thread as well as the blues driver threads that got worked out.

I do know what you mean about the Klon taboo though. Curiously quiet around here huh?

Maybe the "buff and blend" circuit would work in place of the Splitter blend? Have you seen that one? It's a Jfet buffer with a blend pot.


John

[markm]

What this is supposed to do is have two seperate gain stages.....well, two seperate gain circuits running opposite each other via the dual gang pot. Turn one up, the other goes down and so on.
Here's a hacked up OD250 schem;



Enjoy!

[Dragonfly]

use a maxim 1044 and run at 18V   

[markm]

use a maxim 1044 and run at 18V   

That's the next step.
First, the main section needs to function and then, tone control and the charge pump can be tacked on! 

[John Lyons]

I think Fredd said this before but the diodes are going to clip both sections right? Not sure how to get around that other than the blend being at the end of each circuit...

What about buffering each signal at their outputs and using a blend pot?

John

[yeahyeah]

A few things I would improve on from what i see on that schem...

you might want to buffer the input

You need to make sure that the output levels on both "channels" are equal...so that when gain is at 12 o'clock you will have an even mix...if you dont do that, one will overpower the other.

I would set the "clean" side to give a flatter EQ than the OD.

Both ICs can use the same bias network...the two 20k resistor voltage devider only needs to be there once.

the dual ganged gain pots may not give you the effect you are after and may change volume throughout the sweep...

breadboard and tweak it!

just my .02

[freddd]

Defiantly keep at it mark! I would offer more help but I've got a *hell* of a lot on at the moment.

I know I keep harping on but the blend idea works real well. It allows you to get just the right volume mix really easily. Maybe the buff'n blend would work (But remember that buffer on the OD250 output!) Essentially you could use two fixed resistors instead of the blend pot to mix the outputs - You would probably end up doing this anyway to get the required volume levels to match.

I'll try and draw up a schemo later with a few of my ideas.

Jaytee posted a good fix for the gain pot problems a little earlier. I'm sure with a bit of tweaking you could get a really nice (And probably unique  ) OD pedal here. It's well worth the work when you come up with something new, that you've worked on and put some thought into - it always sounds so much better 

[markm]

A few things I would improve on from what i see on that schem...

you might want to buffer the input

Why? How would this improve the circuit?

You need to make sure that the output levels on both "channels" are equal...so that when gain is at 12 o'clock you will have an even mix...if you dont do that, one will overpower the other.

That is an issue although, The Crank suffers from this a bit as well as some other circuits of the same type.
I expect that "as-is" it will do this.

I would set the "clean" side to give a flatter EQ than the OD.

Personal preference?

Both ICs can use the same bias network...the two 20k resistor voltage devider only needs to be there once.

Yes, I know. The schem was a throw together last night at around mid-night. Check the layout, it has only one bias network.

the dual ganged gain pots may not give you the effect you are after and may change volume throughout the sweep...

I'm not sure if you and I are on the same page as to what effect I am after?
As far as sweep, I am aware of this, I'll have to see just how drastic the difference is.

breadboard and tweak it!

just my .02

Thank for the 2 cents!!

I don't know if all of us are aware of the fact that this isn't neccessarily a "Blend" circuit........it is but it isn't.
For the most part, one could build ANY circuit inside the ROG Splitter Blend and be done with it.
Hell, I could just build a Splitter Blend stand alone, plug my OD250 into one side and not have to endure anymore of this!!
But, It's not just a BLENDER!!
Okay, that said, My concerns about buffering and seperate buffers and blenders and such, the OD250 circuit is quite unique on it own and once I start sticking all this fancy extra stuff in there, it become IMO just another "sterile" overdrive.
I already have some of those!

[slacker]

On that hacked up schematic isn't the buffer on the wrong side? It needs to be after the diodes on the dirty side, then you mix the output of the buffer with the output of the clean side. This way the output from the clean side is isolated from the diodes and so won't get clipped. Then you just need to use a couple of mixing resistors to balance the volumes from both sides.
I can knock up a quick schemo of that section if you like.

[markm]

On that hacked up schematic isn't the buffer on the wrong side? It needs to be after the diodes on the dirty side, then you mix the output of the buffer with the output of the clean side. This way the output from the clean side is isolated from the diodes and so won't get clipped. Then you just need to use a couple of mixing resistors to balance the volumes from both sides.
I can knock up a quick schemo of that section if you like.

Yeah.....it is!! 
I think it would be a tremendous help if you could my friend! 

[freddd]

Heres a quick sketch of what I mean. Can you see what I'm getting at?

Notice the microamp section + buffer running at 18v. I haven't sketched the voltage doubler circuit  or placed on the bias network but you know what they look like....

Possible expansions could be a tone control. You could just tack one on the end but I'd be tempted to place it on the OD250 side, just before the clipping diodes in place of the 10k resistor. Mark Hammers SWTC would go perfectly. Also a simple JFET buffer on the front, I'm not sure if it would benefit from having one there but what the hell.

[markm]

I see what you're getting at here fred, look good actually and makes a bit more sense to me now.
Looks like you'd be using Dual op-amps and one side of each as a buffer.
Interesting for sure.
Maybe I'll try doing a layout for this one. The OD250 side will lose some of it's "charm" without a 741 though.

[freddd]

Yeah, I think we were getting wires crossed but we were both basically thinking the same thing.

I thought about the 741 thing, I suppose you could use 2 singular op amps, one 741 and a TL071 or something, but that would just be a waste of space really.

[markm]

Yeah, I think we were getting wires crossed but we were both basically thinking the same thing.

Yeah, I think so! 

I thought about the 741 thing, I suppose you could use 2 singular op amps, one 741 and a TL071 or something, but that would just be a waste of space really.

Yes.
It would certainly increase the size for sure.
The trimmers at the gain pot could probably be replaced with a fixed resistor once the balance was established.
What about a 100K dual or 50K dual for the gain.....better maybe?

[freddd]

I think 50k would be enough. The gain only really starts to climb when you get the resistance down to around that point anyway. I only have 10k dual and that wasn't large enough to reduce the gain low enough on either side. I wish I had more breadboards, all mine are full again This will definatly have to got back on one soon though - it's just getting interesting