Hi ya fellas,
I've been thinking, and that is dangerous sometimes for all of us, :P
But, I came up with this Blendable type OD based on the OD250 type circuit that for the most part, incorporates the standard OD250 circuit along with a "Clean" version with no clipping diodes and a TL071 op amp.
The idea is to have the Gain control set-up similar to the Klon or The Crank using a Dual Gang pot where when one side is max, the other is minimum and so on.
I'm a bit confused as to whether this here would work as I have the 2 circuits sharing the same input cap and also they share the same output to the volume control.
Any opinions as to whether they would work together when set up like this or, should I just call it a day on this one?!
Please have a look at the layout.
I have no schem as it's just 2 OD250's put together.
(http://i17.photobucket.com/albums/b72/mmarkmm/Cascade.gif)
just a quick thought, and i dont know if this will help, but i would look at using one input that splits into 2 input sections, so you can raise the impedance of the "boost" OD250.
???
Well, the only shared part on the input is the input cap......is that going to really screw up the impedance?
Hey mark, quick work!
If you used a couple of dual op amps (as it is "rumoured" the real deal does!) you could place an input and ouput buffer around the two circuits. ~Or you could place a buffer in front of either circuit so that both sections have equal input impedance.
Quote from: markm on July 15, 2007, 11:30:53 AM
Well, the only shared part on the input is the input cap......is that going to really screw up the impedance?
im not saying "screwed up"...i'm saying that it would be preferable, IMO, to have your gain circuit at a low input impedance, and your clean boost circuit at a higher impedance. :)
Just my opinion
Quote from: Dragonfly on July 15, 2007, 11:57:44 AM
Quote from: markm on July 15, 2007, 11:30:53 AM
Well, the only shared part on the input is the input cap......is that going to really screw up the impedance?
im not saying "screwed up"...i'm saying that it would be preferable, IMO, to have your gain circuit at a low input impedance, and your clean boost circuit at a higher impedance. :)
Just my opinion
Ahhh.
Okay, I see what yer getting at here AC.
Quote from: freddd on July 15, 2007, 11:56:12 AM
Hey mark, quick work!
If you used a couple of dual op amps (as it is "rumoured" the real deal does!) you could place an input and ouput buffer around the two circuits. ~Or you could place a buffer in front of either circuit so that both sections have equal input impedance.
That's a good idea.
Yeah, I have "heard" the original has duals, I can't confirm it but, that's the word on the street.
I guess I was attempting to keep it "simple" so to speak.
My other concern is, since the "clean" side has no diodes in the ouput, it will be much louder than the "clipping" side so, that's something to work out as well. :icon_rolleyes:
Wait a minute though.....
Won't the TL071 provide a higher impedance than the 741 or, am I sadly mistaken.
(Don't worry about it, I used to being wrong!) :icon_confused:
Quote from: markm on July 15, 2007, 12:05:01 PM
Wait a minute though.....
Won't the TL071 provide a higher impedance than the 741 or, am I sadly mistaken.
(Don't worry about it, I used to being wrong!) :icon_confused:
you know what...i didnt even notice that you were using 2 different op amps.
the tl071 has a jfet input stage that has a high input impedance. :icon_redface:
so youre safe :)
That's kinda what I was thinking when I did that but, hey.....I'm no designer, and I'm no EE.
I'm just a "circuit-hack"!!
That's what makes me so dangerous! :icon_twisted:
Build it, build it, build it! And tell us what it sounds like!
Quote from: freddd on July 15, 2007, 12:12:36 PM
Build it, build it, build it! And tell us what it sounds like!
:icon_lol:
Well, I thinks that's what I'm going to have to do and then work some of the bugs out from there.
I think I'm going to have to lower the gain on the 071 side a bit 'cause I know it's not going be close to the 741 side.
That's when I'll screw it up!
Should work Ok, the input impedance of both sides is high enough that even though they're in parallel to each other they shouldn't load the signal down or anything.
Like you said you'll probably want to lower the gain of "channel B" because it will be much louder than "channel A" and if you crank the gain high enough you'll get distortion from the opamp even without any clippers.
I'd probably add a resistor between the top of C5 and lug 3 of the volume pot instead of having a straight connection. That way this resistor and R13 could be adjusted to balance the outputs from both sides. You could even use a trimmer with the middle lug going to lug 3 of the volume pot and the outside lugs going to either channel. Hope that makes sense :)
Actually, thinking about it you need a buffer after the clipping diodes on "channel A", otherwise the clipping diodes are attached to the outputs of both channels. This means your clean channel is going to get clipped as well as the dirty channel.
Quote from: slacker on July 15, 2007, 03:21:49 PM
Actually, thinking about it you need a buffer after the clipping diodes on "channel A", otherwise the clipping diodes are attached to the outputs of both channels. This means your clean channel is going to get clipped as well as the dirty channel.
Yes, I see.
Very true. Simple Jfet buffer would probably suit it well or, I suppose I could get "fancy" and use the TS type.
As I sit here and stare at it I do realize that oversight.....the diodes are in the signal path no matter what.
The other thing you could do is stick the clipping diodes in the feedback loop of the opamp TS style. That way you wouldn't need the buffer.
It's a cool idea, be interested in hearing how it turns out :)
I just breadboarded one up now. Sounds pretty good. I stuck a buffer on the end of each section though. And also one on the input. Buffer central really :-\
I'll have a fiddle some more - need to get the overall volumes of both side equal, I think this is going to be the key issue here.
Quote from: slacker on July 15, 2007, 04:17:02 PM
The other thing you could do is stick the clipping diodes in the feedback loop of the opamp TS style. That way you wouldn't need the buffer.
It's a cool idea, be interested in hearing how it turns out :)
I really want to stay away from that TS type soft-clipping if possible, I'm an OD250 guy!! :D
My thoughts are, the buffer to help isolate the clipping diodes will not be hard to add.
Perhaps even the front-end could be buffered as well which may help any possible impedance issues.
At this point, I going to try and get the basics working on it for now then, possibly the charge-pump on the "clean" side for 18V and a tone control such as the SWTC maybe.
Quote from: freddd on July 15, 2007, 04:21:02 PM
I just breadboarded one up now. Sounds pretty good. I stuck a buffer on the end of each section though. And also one on the input. Buffer central really :-\
I'll have a fiddle some more - need to get the overall volumes of both side equal, I think this is going to be the key issue here.
Can you try just buffering the clipping side and tell me if it works or not??
I agree,
balance is gonna make or break this thing! :icon_confused:
Yeah, I'll give it a pop. I'll try running the microamp side at 18v too, just using two 9v batteries in series.
I think the SWTC would be a good choice - I'll try that too. The tone control of the original operates as a high cut I believe.
Quote from: freddd on July 15, 2007, 04:32:46 PM
Yeah, I'll give it a pop. I'll try running the microamp side at 18v too, just using two 9v batteries in series.
I think the SWTC would be a good choice - I'll try that too. The tone control of the original operates as a high cut I believe.
That would be great!
I'm not trying to clone the Klon, just make something similiar......hey, ya know.......
We could all team up and enter this thing into the FX-X as a group and kick everybody's butt!! :icon_lol:
:) gotcha. heh. It's 10PM here though so I'll probably do that tomorrow. I'm sure with a bit of work it'll be great. With the gain in the middle you get a cool fizz over the clean sound - very pleasing!
Based on the claim that the original tone control is "neutral in the middle", I think that the circuit uses either a BSIAB-type tone control, or an active circuit such as the baxandall. Based on my own fooling around, the latter can give a very 'transparent' sound, enabling a more or less independent boost or cut of the high frequencies. It might actually be possible to improve on the Klon by using individual bass and treble controls, rather than just a single knob TC. The baxandall would lend itself to that very well, although I suppose the more tone controls there are, the further away from the 'transparent' goal you get.
As to getting the balance of gain right between the two stages, how about putting a fixed resistor in parallel with the half of the dual gang pot responsible for adjusting the gain of the OD250 stage? That seems like it would be a pretty quick fix, without greatly effecting the frequency response of the circuit. Actually, looking at the schematic, I might raise the value of the capacitor from the inverting input of the opamp to ground, in the hopes of reducing the hi-pass effect. Not that I know what the hell I'm talking about :). Well, now I know what I'm going to spend the next week fooling around with!
Kudos Mark, this is a good idea. I have been working along similar lines recently, but due to a stupid tendency to over-complicate things I haven't gotten nearly so far. Very interested to see where this ends up. Thanks!
Carl
I like the idea of a baxandall. I like the SWTC for it's transparency - you can trim just enough of the highs to stop your ears sizzling.
It's not the relative gain that is the problem - it's the volume of the two sections (The OD250 is quieter than the microamp due to the clipping) slacker came up with a good fix a couple of posts back I'm implementing it as we speak.
Quote from: BlueToad on July 15, 2007, 05:03:33 PM
Well, now I know what I'm going to spend the next week fooling around with!
Kudos Mark, this is a good idea. I have been working along similar lines recently, but due to a stupid tendency to over-complicate things I haven't gotten nearly so far. Very interested to see where this ends up. Thanks!
Carl
Thanks for the kind words Carl....been thinking about this now and again for some time now but, finally came up with something reasonable, I think ???
The jury is still out!
I'd like to keep it simple with the SWTC, but who knows at this point.
Here's a look at it re-arranged with a Buffer at the end of the "dirt" side and a change to the resistor at the gain from 47K to 4.7K in hopes of making up for some loss from the clipping section.
(http://i17.photobucket.com/albums/b72/mmarkmm/CascadeB.gif)
I think the output of the dirty side is restricted by the diodes at 0.6v pk pk. At first I thought of lowering the gain of the clean side, but then if you want to have high output maybe the buffer can be made to have some gain, maybe 2-4 times. I'm not sure how noisy it would get. I like asymetrical Ge diodes in a circuit like this. I believe the pedal in question uses Ge clipping?
Quote from: jaytee on July 15, 2007, 09:24:10 PM
I think the output of the dirty side is restricted by the diodes at 0.6v pk pk. At first I thought of lowering the gain of the clean side, but then if you want to have high output maybe the buffer can be made to have some gain, maybe 2-4 times. I'm not sure how noisy it would get. I like asymetrical Ge diodes in a circuit like this. I believe the pedal in question uses Ge clipping?
Both good points.
Ge's in the Klon huh? Now that you mention it, I have may have heard that somewhere but, I'm not sure.
Hey Mark. I tried what you asked - It didn't like not having a buffer on both outputs. The Micoamp seemed to go a bit fuzzy.
the microamp sounds good at 18v, lots of headroom. I placed a simple volume control on the clean boost side (Just a 100k trim to ground) - made it easy to balance the volumes.
I did work out a problem though - I havn't been using a dual ganged 470k rev log pot (just 2 470kB) Now if I did use a dual ganged pot wouldn't one of the tracks be working in the wrong direction (As it is a reverse log)? I've been trying to adapt the design to use 2 10kB pots, I'm sure this would be better.
Cool!
Must build this quite soon!
Quote from: freddd on July 16, 2007, 05:55:25 AM
Hey Mark. I tried what you asked - It didn't like not having a buffer on both outputs. The Micoamp seemed to go a bit fuzzy.
the microamp sounds good at 18v, lots of headroom. I placed a simple volume control on the clean boost side (Just a 100k trim to ground) - made it easy to balance the volumes.
I did work out a problem though - I havn't been using a dual ganged 470k rev log pot (just 2 470kB) Now if I did use a dual ganged pot wouldn't one of the tracks be working in the wrong direction (As it is a reverse log)? I've been trying to adapt the design to use 2 10kB pots, I'm sure this would be better.
It would be a B500K, a dual gang linear but, reverse wired like The Crank and the SparkleDrive etc.
The idea is to have the dual gang set up, like the Klon.
The trim control seems like a good temporary "fix" however, maybe you could measure the resistance set by the trimmer and replace it with a resistor of the same value?
Too bad about the buffer, perhaps the design is going to have to take another turn and become a bit more complicated?
What about an IC buffer; one at the start to split the two signals into two individual sources and one at the end to buffer all?
Quote from: Bernardduur on July 16, 2007, 08:04:16 AM
What about an IC buffer; one at the start to split the two signals into two individual sources and one at the end to buffer all?
I suppose that would work as well.
Perhaps use 2 dual op-amps, one side on each one as a buffer. :-\
Quote from: freddd on July 16, 2007, 05:55:25 AM
Hey Mark. I tried what you asked - It didn't like not having a buffer on both outputs. The Micoamp seemed to go a bit fuzzy.
Did you put a 10k resistor after the buffer? I think you need something like that to mix the outputs.
Quote from: jaytee on July 16, 2007, 08:47:52 AM
Quote from: freddd on July 16, 2007, 05:55:25 AM
Hey Mark. I tried what you asked - It didn't like not having a buffer on both outputs. The Micoamp seemed to go a bit fuzzy.
Did you put a 10k resistor after the buffer? I think you need something like that to mix the outputs.
Ummm, I didn't put a 10K in the layout, I don't know if freddd did or not......how 'bout it freddd? ???
Are you suggesting the 10K after the 10uf cap from the buffer or before it?
After the cap. One end to C9 the other end to R13.
Nope, I didn't place any resistance after the OD250 buffer. Just had it running to the same point as the microamp output.
I tried something a little different mark. I took the splitter blend design from runoffgroove and removed the phase switching part (So it basically had two "red" lines). Between the "green" send and return points I placed the OD250 and between the "red" the microamp. The blend control can then be used to dial in just the right volume of microamp boost. You can then wire up your gain control and hey preto . . . .
The thing with linear pots is the change in gain isn't regular at all, it's all rammed down one end of the pot so when you have the gain control wired up your just going to get two extremes on either side of its rotation with nothing in between.
Interesting.
Perhaps the gain could be a B50k or B100k dual.
The idea of the blendable gain is to model it after the Klon.....I just don't want to make it overly complicated and if I add all of the controls then TMK syndrome sets in. :icon_razz:
You don't actually have the 25k blend control as a pot. You can just replace it with two fixed resistors when you decide the balance is right. It's just a circuit "restructure". This just leaves you with the original controls you outlined - gain and volume (with "tone" if you decide to add it)
I think 50kb sounds best. I wish I had one to try it out!
You could use a 1M LIN dual pot then use resistors to contour each side as in the info over at GEO to get the response and gain that you want.
Very true.
I think what I'm going to have to do at this point is one of 2 things;
1) give it up......it's on the right track but, no cigar
-or-
2) Build it and try and work some of the bugs out of it from there.
Any other thoughts fellas?
2!
Else I will build it :)
The idea is pretty great; and fit's right into my niche of pedals I need to build quite soon; alas to say the shop I get my stuff from is closed now so I can't build that quick!
Build it, but like I suggested - in the loop of the splitter blend. It sound pretty cool.
Quote from: freddd on July 16, 2007, 04:43:20 PM
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! :icon_wink:
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.
If you want to get the big guns in on it post the schematic. Those guys are suckers for schematics. ;D
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
Quote from: magikker on July 16, 2007, 06:14:37 PM
If you want to get the big guns in on it post the schematic. Those guys are suckers for schematics. ;D
:icon_lol:
That's funny but, highly unlikely.
Quote from: John Lyons on July 16, 2007, 06:29:31 PM
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!
Quote from: John Lyons on July 16, 2007, 06:29:31 PM
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?! :icon_lol:
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!!
Schem for the OD250 can be found here;
http://www.montagar.com/~patj/dodoverd.gif (http://www.montagar.com/~patj/dodoverd.gif)
Many thanks.
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
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;
(http://i17.photobucket.com/albums/b72/mmarkmm/overdrriveschem.gif)
Enjoy!
use a maxim 1044 and run at 18V ;)
Quote from: Dragonfly on July 16, 2007, 11:41:15 PM
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! :)
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
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
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 :D) 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 8)
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
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?
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
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.
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
I would set the "clean" side to give a flatter EQ than the OD.
Personal preference?
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
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.
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
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.
Quote from: yeahyeah on July 17, 2007, 01:07:31 AM
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!
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.
Quote from: slacker on July 17, 2007, 07:53:30 AM
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!! :icon_redface:
I think it would be a tremendous help if you could my friend! :)
(http://img404.imageshack.us/img404/7231/klonlikevs2.th.jpg) (http://img404.imageshack.us/my.php?image=klonlikevs2.jpg)
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.
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.
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.
Quote from: freddd on July 17, 2007, 09:56:14 AM
Yeah, I think we were getting wires crossed but we were both basically thinking the same thing.
Yeah, I think so! :D
Quote from: freddd on July 17, 2007, 09:56:14 AM
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?
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 :D
I liked the idea of a discrete buffer just on the clipping side. It's simpler and I don't see the need for it on the clean side. Maybe the clipping diodes could be doubled or tripled to get more headroom on that side. Running the clean side from 18v there's the problem of going from a clean boost with lots of headroom to something that's limited by the diodes. Which is why I thought the buffer could be made to boost a bit.
Just a thought:
Maybe you can take a look at the Sparkle Drive and exchange the OD section with the OD250?
Quote from: jaytee on July 17, 2007, 10:30:43 AM
I liked the idea of a discrete buffer just on the clipping side. It's simpler and I don't see the need for it on the clean side. Maybe the clipping diodes could be doubled or tripled to get more headroom on that side. Running the clean side from 18v there's the problem of going from a clean boost with lots of headroom to something that's limited by the diodes. Which is why I thought the buffer could be made to boost a bit.
Well jaytee, I kinda thought what you said made sense so, I incorporated that discrete buffer into the current layout and I am prepared to test it as is this evening.
I like the simplicity of it as well. That was the appealing thing! :)
Quote from: geertjacobs on July 17, 2007, 10:37:27 AM
Just a thought:
Maybe you can take a look at the Sparkle Drive and exchange the OD section with the OD250?
Been down that road before. http://aronnelson.com/gallery/album76/SparkleDrive_LAYOUT (http://aronnelson.com/gallery/album76/SparkleDrive_LAYOUT)
It could certainly be done but, complications set in and although the SparkleDrive is a great circuit, the OD250 would probably end up sounding "neutered" within that SD design.
What freddd has posted is basically how I'd do it, except that you shouldn't need the buffer on the clean side.
This means you could still use a 741 for the OD250 side and use half a TL072 for the clean side and the other half for the buffer, or just use a discrete buffer.
Quote from: slacker on July 17, 2007, 12:20:20 PM
What freddd has posted is basically how I'd do it, except that you shouldn't need the buffer on the clean side.
This means you could still use a 741 for the OD250 side and use half a TL072 for the clean side and the other half for the buffer, or just use a discrete buffer.
I see.
That way it could retain some of the 741 "flavor" and mojo!
Good idea!
that's the same idea as the 5089 buffer......isolate the clipping diodes.
Here's what I was thinking.
(http://www.geocities.com/jrtookmyfalseteeth/buffblnd.gif)
Put the micro amp in before the 10uf cap and put the OD250 in the loop. You may need to adjust some levels but it's an idea...
John
I think we ought to put this whole big mess into a wah pedal case. Then set it up so that it goes from clean to dirty as you rock your foot.
Quote from: magikker on July 17, 2007, 03:56:27 PM
I think we ought to put this whole big mess into a wah pedal case. Then set it up so that it goes from clean to dirty as you rock your foot.
:icon_mrgreen:
You're a funny bunny Mark, but I like your style ;)
Maybe a tone knob might be cool? :icon_biggrin:
This fella's got the right idea......
http://www.beavisaudio.com/Projects/FuzzLab/ (http://www.beavisaudio.com/Projects/FuzzLab/)
MONSTER FUZZ!!! :icon_eek:
Quote from: geertjacobs on July 17, 2007, 10:37:27 AM
Just a thought:
Maybe you can take a look at the Sparkle Drive and exchange the OD section with the OD250?
That would be this, more or less:
http://happybob.com/rstrand/doodoo.gif
Quote from: Ben N on July 17, 2007, 07:37:30 PM
Quote from: geertjacobs on July 17, 2007, 10:37:27 AM
Just a thought:
Maybe you can take a look at the Sparkle Drive and exchange the OD section with the OD250?
That would be this, more or less:
http://happybob.com/rstrand/doodoo.gif
Now that's the truth! :icon_lol:
I've built that one too...........nice circuit but, not really what I'm after.
I built my original this evening, it has potential but, sadly, not enough! :icon_redface:
I think I'm headed for a redesign using fred's schemo and take it from there.
It probably won't happen too soon though, I need a break from this thing right now. :-\
This thing reminds me a little bit of the stereomicro amp at tone pad...
There are a whole hand full of fuzzes that blend between clean and dirty... Fender Blender as well as others... Maybe we ought to broaden the base of inspiration.
Quote from: magikker on July 17, 2007, 11:09:40 PM
This thing reminds me a little bit of the stereomicro amp at tone pad...
There are a whole hand full of fuzzes that blend between clean and dirty... Fender Blender as well as others... Maybe we ought to broaden the base of inspiration.
It's nothing like stereo microamp or fender blender. There's no blend control.
QuoteIt's nothing like stereo microamp or fender blender. There's no blend control.
Just a dual ganged gain control that at one extreme has the microamp gain at full and the OD250 at minimum and at the other extreme the OD250 gain at max and the microamp at minimum. So as you turn the gain control you get more of a clipped sound and less of a clean boosted sound.
Quote from: freddd on July 18, 2007, 06:04:24 AM
QuoteIt's nothing like stereo microamp or fender blender. There's no blend control.
Just a dual ganged gain control that at one extreme has the microamp gain at full and the OD250 at minimum and at the other extreme the OD250 gain at max and the microamp at minimum. So as you turn the gain control you get more of a clipped sound and less of a clean boosted sound.
Thank you fred and jaytee,
I've been trying to make this clear at times over the course of this thread and, haven't been able to do so.
There is really NO "Blend" so to speak, which probably threw alot of the guys off on this.
Hi, looking at Marks schematic, to sum the two halves together without them interacting, couldn't you put two (say 100K) resistors after the clean section opamp and the clipping diodes, and send that to that transistor output buffer?
I may try hacking this dual gain notion into a Rat sometime, it has this big box with room for all kinds of extra stuff.
Quote from: Processaurus on July 18, 2007, 09:09:52 AM
Hi, looking at Marks schematic, to sum the two halves together without them interacting, couldn't you put two (say 100K) resistors after the clean section opamp and the clipping diodes, and send that to that transistor output buffer?
I may try hacking this dual gain notion into a Rat sometime, it has this big box with room for all kinds of extra stuff.
May work Ben!
The original does work but, not well which was why I am heading toward fred's design which I will build within the next day or 2.
Please post whatever you may come up with and maybe we can develop a great little OD circuit that's a bit "different"! :)
I know there is no "blend control" but I'm thinking that something like this is going to need a blend control, well at least an internal one. Correct me if I am wrong but you don't normally get the best sound if you just combine two parrallel effects with out some sort of "blending circuit." What I'm saying is that it might need a little bit of a simple mixer circuit at the end. You could set the "mix" internally for the best balance and forget about it afterwords.
Just an idea.
http://www.montagar.com/~patj/smixer.gif
Oh, and quick question. You said that the effect had potential but it wasn't what you'd hoped. What did it sound like... that might help people throw out ideas in the right directions.
I think the "Blend" can be adjusted with fixed resistors however, if there's a bit of imbalance between the 2 extreme Gain settings, I can live with that. Most circuits that have any type of Gain control also have a Volume to help compensate for that.
As far as the sound, when set to the extreme Clean side, it was fairly muffled and when set to the extreme Dirty side it was overly crisp and trebeley.
In the middle there were some nice FAT OD sounds but, the selection was limited and was not very usable as anything else.
Versatility I guess you could say was an issue.
Ah ha....
I had guessed that the in betweens were the issue...
So, I guess we need it to be crisper clean on the clean side?
The in-betweens are fine, the extremes are brutal! :icon_lol:
it just struck me... at the extremes you are looking at a full gain distortion plus or a full gain micro amp right? I'm rarely a fan of any of my pedals at full gain... Were as at the extremes you probably want a 75% gain micro amp or 75% gain dist+ and none of the other effect?.... Is that right?
Quote from: magikker on July 18, 2007, 12:24:31 PM
it just struck me... at the extremes you are looking at a full gain distortion plus or a full gain micro amp right? I'm rarely a fan of any of my pedals at full gain... Were as at the extremes you probably want a 75% gain micro amp or 75% gain dist+ and none of the other effect?.... Is that right?
Well, the D+ is a bit different than the 250 but, yes. I would say you are correct however, there will always be a bit of one on the other's full setting.
I myself don't go for Max Gain either, just a bit of break-up 'cause afterall, I play Country!
But, it gets unusable in either extreme where as the individual effects are usable by some at extreme settings.
The sound was, to use a better phrase, "not - pleasant" on the extremes.
A bit clearer would be the phrase, "it sounds like Crap!". :icon_lol:
When I built it on bread board I ended up lowering the gain available in both sections quite a bit, I just increased the resistors that head for ground after the gain pot. I can't remember the exact values I had - they still needed some tweaking anyway.
Quote from: markm on July 18, 2007, 12:42:23 PMWell, the D+ is a bit different than the 250 but, yes. I would say you are correct however, there will always be a bit of one on the other's full setting.
I myself don't go for Max Gain either, just a bit of break-up 'cause afterall, I play Country!
But, it gets unusable in either extreme where as the individual effects are usable by some at extreme settings.
The sound was, to use a better phrase, "not - pleasant" on the extremes.
A bit clearer would be the phrase, "it sounds like Crap!". :icon_lol:
So this is meant to be an Old 97s pedal? ;)
Quote from: freddd on July 18, 2007, 12:54:25 PM
When I built it on bread board I ended up lowering the gain available in both sections quite a bit,
Now that would not surprise me at all!
I just finished this pedal, and it simply ROCKS!!!!!
The max settings are nice as you get a clean boost as a Distortion + like tone but the inbetween sounds are really killer as they tend to go from slight OD's to more distortion....... one problem is that the volume increases as I tend to go to the max settings..... in between the volume is quite lower then the extremes.
I run it now on 18V; they are just a microamp and a OD250. I simply placed an IC buffer stage / splitter before to get enough sound to both sections
Did you build freddd's circuit?
So, you have a buffer on the input and that's all?
Quote from: markm on August 06, 2007, 11:41:33 AM
Did you build freddd's circuit?
So, you have a buffer on the input and that's all?
Almost :)
I didn't use a buffer on the end but placed it to the start; the signal goes through two mix resistors to the 100k (log) volume pot
I also didn't add the trimpots yet; they'll come later I guess as I will replace the mix resistors with trimpots. I also added a cap over the 250 diodes.
Oh, and I kept the pedals individual 1/2V+ maker intact; I dunno if that is advised over one 1/2V+ maker for all positions.
I'll make a schematic of it
It sounds really really good!
Schematic link (http://www.student.ru.nl/r.kerkhof/ODi.jpg)
Quote from: Bernardduur on August 06, 2007, 12:36:59 PM
Schematic link (http://www.student.ru.nl/r.kerkhof/ODi.jpg)
Thanks for that link Rogier, I'm going to have to try this thing out! 8)
Yes;
I would love to have the volume a little bit more even but it is a GREAT pedal to play with!
Great stuff! It works... Interesting changes your made there. Are you gonna attempt to solve the volume issues?
Yep; I am quite busy now (although my bass needs me first)
Noticed some mistakes in the schematic I will undo quite soon;
- The output cap on the microamp section is 15 uF, not 10 uF
- The volume pot is log; the program has no log pots
- Both gain potmeters are a double potmeter as described in the before section
Quote from: freddd on August 07, 2007, 06:31:55 AM
Great stuff! It works... Interesting changes your made there. Are you gonna attempt to solve the volume issues?
Probably just an adjustment of the 10K mix resistors in the schem.
Although, would this not effect the highs a bit?
Yes, it would I guess;
So therefor I go to mixing volume trimpots;
So, what the consensus on the bias network?
Should it be shared amongst the two individual circuits -or- should each side have it's own since the values are different?
No opinions I guess :)
When I connect all pedals to the same bias network the "sound" of the individual effects get less. So keep em in!
did anyone ever get this thing working? the links are dead.