Okko - Diablo Boost+ (goop pics!!)  [traced]

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby alkuz1961 » 02 Apr 2014, 22:12

RomYch, good work but a lot of empty space. This pedal can be much small... 8)
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby RomYch » 03 Apr 2014, 11:30

alkuz1961, :applause:
Size does matter (размер имеет значение)! :D
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Okko Diablo schematic is wrong!

Postby bordonbert » 21 Oct 2014, 16:28

Hi guys. I've been doing a lot of work on setting up my own overdrive circuit based on the Okko Diablo type of circuit. I started with the usual online schematic which I found in a number of places. When I looked at it and started to dissect the whys and wherefores I couldn't get my head straight. It's wrong! And it's wrong in a big fatally flawed way.

Each stage of the Diablo and the single stage of the Boost are based on a 2 x JFET circuit which is based on older valve technology. It is in fact a lower common source amplifier and an active load with refinements. At first sight the stage looks like a basic Muamp, but it's not!!! The Muamp has a high output impedance which will not cope with the loads imposed on it by the following signal shaping circuitry in the Diablo and the volume pot in the Boost. Gain will be low, tone will be rough, controls will not work as they should. (I know, I built it to check!)

The giveaway is that each stage has a resistor between the two JFETs. As they are wired up they do absolutely nothing at all! This circuit is intended to be a SRPP type rather than a Muamp type. There is a very good article here: http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm which clearly shows and lays out the differences. (It's good for the not so technically gifted too.) You can clearly see what is wrong. All that is needed to make the circuit work as intended is to shift the lower connection of the gate capacitors from the sources themselves to the bottom of the source resistors. The pic should make that clear.

Diablo_Stage_Corrected.jpg


For anyone who does not understand the circuit action I will stress, this may look like a tiny change. I can assure you it is not! The circuit cannot work anywhere near as intended in the original state. Can any other technically experienced guys check this out and confirm it please? (Everyone's work should be "peer reviewed" before being accepted as fact. :D )

When I originally found this I posted here: http://www.madbeanpedals.com/forum/index.php?topic=17962.0 and a good guy, Drolo, commented on it and helped in the thought process. I have done a running repair and found the whole circuit comes to life and works just as expected with the corrections applied.
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artaommahe (26 Dec 2014, 18:54), Manfred (15 Feb 2016, 22:55), modman (21 Oct 2014, 17:03), rs (28 Oct 2014, 11:29)
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Re: Okko Diablo schematic is wrong!

Postby modman » 21 Oct 2014, 17:08

bordonbert wrote:Hi guys. I've been doing a lot of work on setting up my own overdrive circuit based on the Okko Diablo type of circuit. I started with the usual online schematic which I found in a number of places. When I looked at it and started to dissect the whys and wherefores I couldn't get my head straight. It's wrong! And it's wrong in a big fatally flawed way.


Might be, but only board gut shots from the diablo can prove that. Nothing else.

Diablo_Stage_Corrected.jpg


bordonbert wrote:When I originally found this I posted here: http://www.madbeanpedals.com/forum/index.php?topic=17962.0 and a good guy, Drolo, commented on it and helped in the thought process. I have done a running repair and found the whole circuit comes to life and works just as expected with the corrections applied.

That's very good news, but again. This doesn't prove anything.

viewtopic.php?f=7&t=1482&p=18854&#p71886

The schematic was never traced at freestompboxes.org. The schematics came from a German from musikding, but were never confirmed. This is a GOOPED PEDAL. Maybe we should buy one.
"The whole point of diy is diy. It's not dsoiyathodtr - do some of it yourself and then have others do the rest" (paulc)

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby modman » 21 Oct 2014, 17:17

soulsonic wrote:Bumping this to attach the schematic. I don't remember who traced this one or where I found it... I think I found it at Das Musikding... maybe Kusi traced it?
Anyway, I hope it is okay with the author to post this here.
:D


kusi 08.12.2009, 14:39 wrote:
Mahlzeit,
mal wieder ein sehr beliebtes Thema, ich will hier keinen Plan, kein Layout oder sonst was, ich will nur von euch wissen, ob es im ganzen Internet einen Schaltplan gibt oder nicht, was denkt ihr?

Grüße
Andy


klar gibts den, hab ich ja selbst ge-degoopt und abgezeichnet...

http://forum.musikding.de/vb/archive/in ... 26423.html
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby bordonbert » 21 Oct 2014, 18:04

Does anyone know the workings of the Muamp and SRPP circuits well to be able to confirm my own suggestions? (I mean in the sense of checking me out, not as a challenge to anyone else's experience). It is an understanding of the circuitry which has led me to these conclusions not just fiddling and finding there's a difference. It is a predicted fault from a lifetime of working within the industry on much more complex stuff than this. I can tell you it is set out wrongly.

If it isn't of any interest then so be it, but I urge you to just consider that what I say may be right and look into the links I supplied, particularly the background confirmation site at http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm. Once you understand the simple structure of both types of circuit, muamp and SRPP, and you compare them with the Diablo schematic with its redundant resistors and its relatively low impedance signal shaping, it is obvious that this has been chased out wrongly, and the many reports of poor sound quality by a lot of builders lead us to that conclusion too. Then testing and measuring confirms it, (and finally listening also plays a part of course).

I'm not suggesting the Diablo itself is wrong, (although that is not entirely out of the question as it has been known), only the commonly seen schematic.

(I've done my duty now!) :? :lol:
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby modman » 21 Oct 2014, 19:24

I really think you might be onto something: of course I would urge everyone to build it with these correction, and try it out.
I would like to see some pictures of the board, if we really want to establish the correct schematic for the OKKO. You are supposing their are no 'electronic mistakes' in boutique stompboxes, I think this is wrong.

This whole thread is littered with build pics, while the only point for attachments is documenting the circuitry..
"The whole point of diy is diy. It's not dsoiyathodtr - do some of it yourself and then have others do the rest" (paulc)
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby bordonbert » 23 Oct 2014, 17:15

I've had time now to try this mod in both my Diablo clone and Boost clone pedals I have been working on and I can confirm that, with the exception of a nasty little spurious oscillation at the very top end of the gain setting in the Diablo (which I am sure is down to an "adventurous novel" wiring scheme I came up with which I will have to rework), this seems to be the right way to go. The tone after the mod is much improved (to my ears), and all of the controls work better and in a more balanced way. The tone shaping components seem to be very well chosen in the original.

I would really appreciate someone else who has a Diablo built to the original schematic to change it and test my observation. That is the only way to verify this issue, independent peer review.
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby Chewbacca » 26 Dec 2014, 18:10

I have built an Okko Clone on Vero - built according to the schematic everybody seems to use.
I've had it for a while and have tested it against original Diablos I had at my workshop for repairs. So I am pretty sure my clone sounds like the real thing. Reading bordonberts post, I just opened the thing and installed a switch that switches C4 and C8 to the different ends of R6/R9 respectively.
The difference may be great technically, but soundwise it is not really earthshaking.
I'd say a little less gain and a little less bass content, more clarity, but altogether not much of a difference. Switching back and forth, I am not really sure which version I like better so I'll keep the switch - it adds a little versatility (I even marked it B for "Bordonbert Mod" ;-) I could also call the switch Fat/Low Fat - with Fat being the original configuration.
I am not sure the schematic is wrong - I guess Heiko is laughing his butt off in Leipzig about us trying to figure out what he did under the goop - I would not be surprised if it was him who put the schematic in circulation in the first place.
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby bordonbert » 11 Jun 2015, 13:08

Took me a long time to find this Chewy, thanks for the work and the great results. I've been living with my own revised pedal since my original posts and I still get on well with it. It's strange to find myself on the other side of the fence on this one. For me to be the one saying, "I hear and like the difference" and someone else saying, "There isn't much difference for me to like" is a new experience for me, I'm usually the debunker. :applause: I accept your findings absolutely and I'm left really hoping that our assessment differences are more down to the priorities of our subjective preferences rather than actual physical differences in the sound of the two versions we have made up.

One of the things I always maintain that a pedal should have to be called "well engineered" is absolute repeatability, (and I'm usually at odds with pedal buffs on this one!) It sticks in my craw to have to manually select particular components from the general stock to make something work as it should. If that's the way you work then you're not really cut out to design for a large scale user base, you're only fit to make an individual unit tweaked for your own use, and it's a compromise. If a high gain is required then select an available type and specify a "C" or "red" type over the "magic" one which was used in the 1967 version with the PCB made on Parchment and the wax caps. If your trannies don't go that way, then there are hundreds of others out there which do! That's one of the reasons I liked the Diablo in the first place, the circuit topology was over two stages and was well defined to use the base component types from the outset. (And I reckoned the work done to tie down the filtering aspect was superb).

That said these are FETs and are a bit of a different beast to BJTs in this way. Maybe the individual trimming should just be accepted. Naahh! :idea: We should do what Heiko did originally, split it into more stages and work with less gain in each. Part of his success was in setting up two stages of gain and allowing the ability to trim each so the combination is very flexible. Now could we get round lower gain devices if we considered three stages and..... (And that way lies madness [smilie=new_silly.gif] )

Thanks for the "B" switch designation, though I'm not sure it's deserved. :oops: Kind of puts my head on a stick up above the parapet doesn't it? (That's a cunning plan you have!)
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby megavolt » 15 Feb 2016, 20:24

Hello to all,

new to stompbox building and a new member here, I have build an Okko Diablo Boost clone, thanks to the information here and the veroboard layout from tagboardboardeffects.blogspot.de. It worked nicely from the start and my Digitech Bad Monkey is already retired. Nevertheless, in higher gain it sounds a bit harsh.

Thus I would like to ask if this circuit design should be built with matched jfets Q1-4? What do you think? Could this result in a smoother tone?

Thanks a lot for the input,

Roland
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby Nocentelli » 15 Feb 2016, 22:05

megavolt wrote:I would like to ask if this circuit design should be built with matched jfets Q1-4? What do you think? Could this result in a smoother tone?


Welcome! Matching JFETs (i.e. testing to find ones with very similar characteristics) is usually only done for phasers that use JFETs as the resistive element: You want all of the JFETs to respond in a similar way to the pulsing of the LFO.

Overdrives that use a single JFET per gain stage sometimes need testing to ensure they will "bias up" with the appropriate drain resistor (i.e. have the required voltage at the drain with the given drain resistor), but many designers prefer to put a trimmer in place of the drain resistor, so the voltage can be "tuned" for the actual JFET used. However, the Diablo appears to use pairs of JFETs for each gain stage, in what appears to be a mu-amp configuration: This is usually fairly forgiving, and the variation between individual JFETs seems to have little impact (in my limited experience). If the harshness you describe is to do with the amount of treble in the signal, I would tinker with the values of the components in the tonestack before I started to try different JFETs.
brownwhopping wrote:How can I learn by reading threads an making circuits, when some day I can see a lawsuit or somebody beat me in the face for that?

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby megavolt » 17 Feb 2016, 21:30

Thank you very much, I will try that and post an update afterwards.

And I will replace C8 (1 µF capacitor near Q4), the tagboardeffectslayout uses a polarized capacitor here, I think it should be a plastic film type. :scratch:

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby ozzy666 » 20 Feb 2016, 19:32

Did anyone try this polish copy of the Diablo?
http://www.efekty-diy.pl/diablo.html
I actually have managed to build the pedal just from copying the pictures of pcb on their web site and from reading their BOM.
It worked perfectly! Highly recommended :-)
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby vvv » 16 Mar 2016, 06:30

ozzy666 wrote:Did anyone try this polish copy of the Diablo?
http://www.efekty-diy.pl/diablo.html
I actually have managed to build the pedal just from copying the pictures of pcb on their web site and from reading their BOM.
It worked perfectly! Highly recommended :-)



Somebody should make a vero-layout from that.
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby dutom » 16 Mar 2016, 21:34

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby vvv » 25 Apr 2016, 09:50

dutom wrote:Veroboard
http://www.sabrotone.com :secret:



Sabrotone´s layout says its based on a schematic drawn by Kusi. I´m not sure if thats the same as the http://www.efekty-diy.pl/diablo.html one.
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby neb » 08 Aug 2017, 13:25

I'm designing smd PCB variant of this pedal and will be ordering some PCBs soon. TO92 J201 version is going away (if not gone already). I don't like veroboard approach at all.

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Re: Okko - Diablo Boost+ (goop pics!!)

Postby Jan1966 » 08 Aug 2017, 16:30

ozzy666 wrote:Did anyone try this polish copy of the Diablo?
http://www.efekty-diy.pl/diablo.html
I actually have managed to build the pedal just from copying the pictures of pcb on their web site and from reading their BOM.
It worked perfectly! Highly recommended :-)


Yes the pcb image on the site is perfect for copying using Sprint. I have made and etched pcb from this layout but not got round to building it yet.
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Re: Okko - Diablo Boost+ (goop pics!!)

Postby neb » 11 Aug 2017, 12:06

How is the sound difference between 9V and 18V? I am wondering if I should run it at 18V all the time and drop the switch.
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