Hi I took a little time this evening and whipped up a few layouts and rendered the PNP transfers for the DOD 250 Gray Spec.
I felt bad for my part in the whole earlier fiasco,and did this as my apology to the forum.
Please feel free to use these for all personal use,and John Lyons (and anyone else) has my permission to etch these for anyone if need be.
I know this is a super simple and easy pedal ,and anyone who has made a couple of pedals could whip this up with mods in no time.
I felt like the newbies who are after the DOD 250 or the YJM pedal might find it helpful to get started with.
I really liked the board mounted pots of the last layout that was up for discusion (but the entire thread was deleted in part due to my involvement)
So now anyone who had previously wanted to build the "other" version ,but didnt want to try making their own transfer from what was posted can now build the original version I am posting.
I also did one with much improved filtering of the V+ and Vref ,with an asymetric clipping option.
And then again with dual clipping options,asymetric option, and 3 different EQ(rolloff) selections available along with the above mentioned much improved filtering.
Sorry to say that when I saved the last version DIYLC file it overwrote the simple MOD version ,so I only have two DIYLC files to let you use and tweak further but feel free to use them as starting poins I will upload those too.
They are made to use standard 24 mm pots just solder some clipped leads into the pads and the pots will support the PCB no standoffs needed. :icon_wink:
I did notice the input and output pads are on the wrong sides of the PCB from where they go,sorry about that I didnt notice until I was done making them.I dont think its that big a deal though for this pedal. :icon_redface:
I did double check though and the spacing for the pots is the same as the "other" layout that was taken down,so it will fit a 1590 B enclosure with the pots side by side,but the total PCB size is smaller ,if any one needs help figuring out the switches or pot mounting just post here and I will help out.
Bryan
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43208&g2_serialNumber=1)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43221&g2_serialNumber=1)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43211&g2_serialNumber=1)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43219&g2_serialNumber=1)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43214&g2_serialNumber=1)
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43217&g2_serialNumber=1)
The DIYLC files are in my layouts gallery if they are of any use to anyone feel free to download them.
http://www.aronnelson.com/gallery/main.php/v/Brymus/layouts/ (http://www.aronnelson.com/gallery/main.php/v/Brymus/layouts/)
You will have to click on them twice as the thumbnails didnt come out for some reason.
Bryan
EDIT fixed a couple broken words,w ords
I just noticed the polarity protection diode (D1 in the bottom two layouts) is labeled 1N4007 it should be 1N4001,sorry about that...
Bryan, see that the Steve's topic hasn't been deleted, but only moved in the members area. It's locked, so no new posts allowed, but all the precious info about the pedal are still there. Still I remain in my position, but again I have nothing against Steve and thank him for his research, as his last post of the topic in reply to my question sums it up.
As for the protection diode, the 1n400x are the same, only differing in the max voltage they can handle, so the 4007 can handle high voltage, but it can be obviously used with a 9V. I use whatever I find around (and recycle some from old equipment)
I am glad there is interest in the 250 and 308 - I was playing with my 308 yesterday and still find GREAT - Yngwie, yeah, but I find it good in a more generic hard rock situation (and played some Dokken, Motley, Cinderella tunes...) - So the more info on these pedals the better. I am also proud to have vero layouts in my gallery. Hope you don't mind I put one here too...
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43173&g2_serialNumber=1)
Not at all Renegadrian
I think the more the better, :icon_cool:
I didnt bother to look for that other thread, glad its still available for people to reference for info on the 250.
He did post alot of useful info on the versions of the DOD 250 through the years ;D
I even credited Steve in my layouts since I used his idea of adding the pots to use as stand offs like the original 250s
Thanks for posting your vero layout,that will be even more help for others that like vero better.
Bryan
Hi.
So I will start building it soon. So thank you.
And I did make some changes to the board.
I am planning to build your last version. So, As I dont like to wait, I always make etchants work easy er. So I did with your layout. Its not pretty, but more efficient.
I uploaded PDF file, its ready to transfer. Just print ant your are done. You can feel free to donwload it, I will try to find a better place for it, but for now its on this addres. ( you will have to wait a sec to see the pdf.
http://web.zone.ee/served/foorum/DOD250PCB.pdf
Good luck!
Hey served that looks sweet !
I was going to do that to the transfers ,as I usually do the same thing when using others from the net to save on etchant.
Plus having the ground plane larger helps with sheilding and reducing unwanted noise.
So yeah no problem and thanks for posting it for others to use.
I will probably do that to the other two transfers if no one else does first.
I still have 3 other pedals I want to draw up and post for the forum to share,so its just a matter of getting around to it,ya know.
There are a ton of DOD 250 layouts in the gallery already,but none I know of with the board mounted pots.
I just wanted to make sure anyone who wanted to use the version with board mounted pots had one that was free to use.
Bryan
I have a question you OD 250 guys might answer. I have the YJM 308, and I notice something, when the gain is pushed past about the 2 O'clock position the tone starts to change quite a bit. Is this something the original 250 did, or is it a "problem" with the reissue pedal?.
I'm planning on doing the mods to change it to gray specs, but using the 1458 chip (so it won't be 100% there).
Al
Hi Brymus, thanks for starting this thread about various 250 layouts. Thanks for the crediting too "if" I'm the first to use PCB mounted pots on a clone PCB layout, but the real credit there goes DOD which used them on the actual 250 and YJM308 pedals that I studied. I just figured it was a neat way to suspend the PCB without any added fasteners inside the box so why not? :)
If you'd like I can post the layout transfer that I made for my as-built late 70's gray 250 clone - that you helped assist me in verifying it works. Aron still hasn't created an upload area for me in the Gallery under my name but I can temporaily link them from my Comcast webspace until I code a webpage dedicated to the 250 legacy and about cloning one. I still really want to post them in his gallery because it is a nice comprehensive one stop shop for 100's of different layouts to build from.
What graphic formats are you using so things print out actual size? JPG preview image and PDF scaled at 300dpi? I'll can post both the layout artwork with the component values listed as a build guide and the trace only pattern too for etching.
I don't know if people would like off board wiring info too but the way I did mine was as a template for all my future builds using a single 3PDT footswitch.
Quote from: zombiwoof on June 02, 2010, 03:18:13 PM
I have a question you OD 250 guys might answer. I have the YJM 308, and I notice something, when the gain is pushed past about the 2 O'clock position the tone starts to change quite a bit. Is this something the original 250 did, or is it a "problem" with the reissue pedal?.
I'm planning on doing the mods to change it to gray specs, but using the 1458 chip (so it won't be 100% there).
Al
The tone does change. The resistance and the cap create a "tone control" to ground. It's normal.
-Joe Hart
@ Steve
I have a large collection of 250 and 250 based layouts as I was intending to build one before you started your threads on it.
And as far as I can tell yours is the first to use board mounted pots,aside from that you did do alot of research into the small differences throughout the years ,and I used your pot spacing,so your quite welcome for the deserved credit.
I felt the whole forum deserved credit too,due to the mods and filtering which I learned through reading threads here and there in this forum.
You and anyone else is most welcome to post any layout,artwork,image,shematic ,photo,ect relative to the 250 pedals that you wish to offer to the forum for use.
I would like to have as many different layouts,options,ideas as possible for people to choose from when building this pedal.
A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM and Zak Wylde varients as well.
EDIT I forgot to answer your question about scaling>
When printing layouts made in DYLC I just scale the image until the IC and cap pin spacing is correct.
It usually takes about 3-4 trys to get it just right,then I tape my glossy magazine paper over the one that is correct and print it again for etching.
Quote from: Brymus on June 02, 2010, 04:12:50 PM
A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM and Zak Wylde varients as well.
Cool, besides the grays I was also researching some about the fist 80's yellow 250's and the reissue yellow/YJM308 too. Tell me about that Zak Wylde variant. It was based on the 250 as well? I didn't know that. Also just a quick mention of the MXR Distortion+ deserves mention as the basis for DOD's 250 overdrive circuit. They are almost identical except for component values! The 250 is basically a modified "clone" of it! The Ross Distortion pedal is very similar too so I guess it was common for companies to immitate what each other were doing.
My bad, actually the Zak Wylde is closer to a Tube Screamer than a 250 >:(
EDIT> But yeah anything that is similiar could go in this thread,sometimes I find it helpful to see how a circuit evolves as it is copied from manufacturer to manufacturer,and how it is revised to keep marketing it as new or improved or whatever.
Alot of times revisions are due to parts availabilty other times,just to save money or keep up with the competition.
Quote from: Steve Mavronis on June 02, 2010, 03:21:23 PM
I don't know if people would like off board wiring info too but the way I did mine was as a template for all my future builds using a single 3PDT footswitch.
Personally I like schematics without the wiring, so they are easier to follow - everyone should learn on the separate wiring tutorials, images, and so on and then use them as they like. It wouldn't be helpful to see a 3pdt wiring when I'm using millenium 2 with dpdt...I'd rather see clearly where the input and output are. That's me...
Quote from: Brymus on June 02, 2010, 04:12:50 PM
You and anyone else is most welcome to post any layout,artwork,image,shematic ,photo,ect relative to the 250 pedals that you wish to offer to the forum for use.
I would like to have as many different layouts,options,ideas as possible for people to choose from when building this pedal.
A defenitive history of versions and revisions would be nice to chronical for those interested as well.
I dont think it should be limited to the Grey Spec but include all 250/250 based models including the YJM.
I noticed that I didn't put this layout in my gallery, my bad...Verified by myself! What a pedal!!!
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43234&g2_serialNumber=1)
Okay well here is the PCB layout Rev.8 from my late 70's gray 250 clone (circa 1979 version) that is a working pedal that I renamed as my Neo-Classic 741 Overdrive. Brymus built a prior development version of it for verification and this one is no different except for some very minor touch-ups to the trace pattern. I built two great sounding complete pedals from it in May 2010. What amazes me the most is I wasn't expecting for it to sound good on the 15 watt solid state (new Marshall MG4 series) amp that I use for practicing. You won't believe this but on the amp's clean channel my pedal makes me sound just like I'm playing through a tube amp! I'm not kidding. Quite a pleasant surprise indeed ;D
Print at 300dpi for actual size. I've included a scale PDF version too (just make sure scaling is set to None) and the outer rectangle is just the default ExpressPCB board size so ignore that. The pad holes are not actual size to fit parts. Instead they act like a centerpunch dent for the bit to fall into when drilling the actual sized holes. The PCB size should be approximately 2.0" wide by 1.7" high and will fit within a 1590B sized enclosure.
Here is a 300dpi image of my PCB transfer pattern, and the PDF version is here: http://home.comcast.net/~snmavronis/nc741od8pcb.pdf
Note - I print to transparencies for UV transfer exposure so mirror flip this for the solder side view (so the text reads normally) if doing PnP which I assume is how it's done:
(http://home.comcast.net/~snmavronis/nc741od8pcb300dp1transfer.jpg)
Here is a parts location graphic of the same thing shown from the component side view:
(http://home.comcast.net/~snmavronis/nc741pcb8parts.jpg)
The full schematic (the PCB circuit is within the 4 circled pad markers) for a pedal wiring guide is here: http://home.comcast.net/~snmavronis/neoclassic741sch9.jpg
You notice that's version 9 because I'm working on a new PCB trace re-route Rev.9 to bring the 741 op amp output cap connection to the diode section 100% true to the original gray 250 interconnections of parts to each other.
nice Steve and Adriano
It looks like the only difference between the YJM and the 250 is the taming or anti oscillation cap in the FBL of the 741.
The only difference between the the MXR distortion + and the DOD 250 seem to be minor value changes.
Adriano which pin does the gain lug 1 go to on your YJM vero layout ?
And I should have includued a 10n to ground at the input of the super modded 250 I posted to cut down on hiss introduced at the input.
And I should have added the option of having the small value cap in the FBL of the 741 too.
There should be room to add those by just drilling some extra holes in the existing layout,
But looking at it again I also see where I could have made the layout even better and more compact.
I may do another smaller version to use 16 mm pots,and the other added mods later on.
Quote from: Brymus on June 03, 2010, 02:12:02 PM
Adriano which pin does the gain lug 1 go to on your YJM vero layout ?
Gain lug 1 goes to ground.
I believe the YJM308 uses a different input cap value (0.001uF vs 0.01uF) than the gray 250 as well, besides of course the different op amp too. I have a YJM308 layout that I drew from looking at the real thing with ExpressPCB when I was thinking about modding that pedal:
I was first learning how to use ExpressPCB when I made this. Sorry it's kind of crappy and I should redo it:
(http://home.comcast.net/~snmavronis/yjm308connections.jpg)
With mod instructions from another forum. Personally I'd ignore step 2 and keep that cap to stay in gray specs:
(http://home.comcast.net/~snmavronis/yjm308dod250mod.jpg)
yeah, I built a 250 with an input cap switch (1n-10n) and it's a difference. Obviously the IC is different. (a dual op-amp hald used...)
Quote from: Brymus on June 03, 2010, 02:12:02 PM
nice Steve and Adriano
It looks like the only difference between the YJM and the 250 is the taming or anti oscillation cap in the FBL of the 741.
The only difference between the the MXR distortion + and the DOD 250 seem to be minor value changes.
Adriano which pin does the gain lug 1 go to on your YJM vero layout ?
And I should have includued a 10n to ground at the input of the super modded 250 I posted to cut down on hiss introduced at the input.
And I should have added the option of having the small value cap in the FBL of the 741 too.
There should be room to add those by just drilling some extra holes in the existing layout,
But looking at it again I also see where I could have made the layout even better and more compact.
I may do another smaller version to use 16 mm pots,and the other added mods later on.
AnalogMan says the extra 25pf cap is used in the 308 because they used a 4558 in the pedal (actually only half of the dual 4558 IC), which has a wider frequency range than the original 741 IC. The added cap attempts to make the 4558 sound more like the 741 circuit, and isn't needed if you are using a 741 in there. One of his mods uses a 1458 instead of the 4558, which according to him is actually a dual version of the 741 chip, and sounds more like it in the circuit (and also doesn't need the 25pf cap). He says the 308 does sound a little noisier with the 1458 in place of the 4558, but closer in sound to the 741.
Maybe you are already aware of this, but you mentioned having the option of using the 25pf cap with the 741, which shouldn't be necessary.
Al
This might be semi-off topic so ignore if it is. I was wondering if there was a listing of what guitarists over the years used or are using a DOD 250, YJM308, or even someones's 250 clone? The only ones I know about for sure (besides us amateurs) is Yngwie Malmsteen (gray 250 and YJM308), Joe Stump (gray/yellow 250's and modded YJM308), and his protege Dean Cascione uses a modded YJM308 and a 250 clone from FX Doctor. Please add to this list if appropriate. Even classic songs that were recorded using a 250 would be cool to know about just to go back and hear the sounds.
Quote from: zombiwoof on June 03, 2010, 03:45:38 PM
Quote from: Brymus on June 03, 2010, 02:12:02 PM
nice Steve and Adriano
It looks like the only difference between the YJM and the 250 is the taming or anti oscillation cap in the FBL of the 741.
The only difference between the the MXR distortion + and the DOD 250 seem to be minor value changes.
Adriano which pin does the gain lug 1 go to on your YJM vero layout ?
And I should have includued a 10n to ground at the input of the super modded 250 I posted to cut down on hiss introduced at the input.
And I should have added the option of having the small value cap in the FBL of the 741 too.
There should be room to add those by just drilling some extra holes in the existing layout,
But looking at it again I also see where I could have made the layout even better and more compact.
I may do another smaller version to use 16 mm pots,and the other added mods later on.
AnalogMan says the extra 25pf cap is used in the 308 because they used a 4558 in the pedal (actually only half of the dual 4558 IC), which has a wider frequency range than the original 741 IC. The added cap attempts to make the 4558 sound more like the 741 circuit, and isn't needed if you are using a 741 in there. One of his mods uses a 1458 instead of the 4558, which according to him is actually a dual version of the 741 chip, and sounds more like it in the circuit (and also doesn't need the 25pf cap). He says the 308 does sound a little noisier with the 1458 in place of the 4558, but closer in sound to the 741.
Maybe you are already aware of this, but you mentioned having the option of using the 25pf cap with the 741, which shouldn't be necessary.
Al
Yeah your right Al,I was overlooking the use of different op amps,also
I was thinking in terms of reducing the hiss in the upper end of the frequency range,but that would detract from the "sound" of the 741 and it would also probably take something closer to a 50-100p cap to do that.(some breadboarding would be needed to say for sure)
nice catch on that thanks.
@Steve, No I think those YJM layouts are good here :icon_wink: ,so is the list of artist who use the pedals,even better a list of albums and tracks to give an idea of the sound in the right hands with the right amps.
I also think if you still have them ? Pics of the outside and inside of the different models in chronological order would be a really cool addition to this thread.
Quote from: Brymus on June 03, 2010, 06:11:27 PM@Steve, No I think those YJM layouts are good here :icon_wink: ,so is the list of artist who use the pedals,even better a list of albums and tracks to give an idea of the sound in the right hands with the right amps. I also think if you still have them ? Pics of the outside and inside of the different models in chronological order would be a really cool addition to this thread.
The YJM layouts as far as the PCB goes is the same as used on the yellow reissue pedal except they use different part values. Yeah I'm glad you also want to know the tracks the 250 was recorded on. Probably more classic songs than we realize now. For pictures I have folders on my hard drive were I've separated 250 pedals by year. Now some of them are based on what the owner said they were and what the CTS pot date codes say about when they were made before being installed in the unit. Let me organize a representation of them throughout the years and I'll post them with inside and outside shots. I've also noticed over the years the DOD logo changes position from left side to right side and back, which also sometimes helps when dating them.
@zombiwoof
If memory still serves well, the use of a 1458 in a 308 instead of the 4558 is easy because they share the same pinout, while 741 has a different pinout, so it's not a direct replacement...
^^^ Correct.
Quote from: Renegadrian on June 03, 2010, 07:01:45 PM
@zombiwoof
If memory still serves well, the use of a 1458 in a 308 instead of the 4558 is easy because they share the same pinout, while 741 has a different pinout, so it's not a direct replacement...
Yes, I'm aware of that, Analog Man also does a full mod to gray spec of the reissues that uses a 741 chip, but it necessitates rerouting the pins because of the difference. The 1458 mod he does is a "close but no cigar" mod that gets you into the ballpark of the original, but is easier because as you say the pinout of the 1458 is the same as the 4558. I'm going to go the easier route and use the 1458, remove the 22pf cap, and change the input cap to a .01uf and see how it sounds. I don't think there is any more to it, but I'll compare the components to the gray 250 component list and see if anything else is out of whack.
Of course, this is on a long list of projects I'm aiming to do in the near future when I can get to them!
Al
Hey all. Just a minor gripe I hope. I have a problem at that "other" forum. If JOHNO (who also is a member here) is going to take my PCB transfer graphics from "this forum" and repost it on the other "Free.........." forum with a sarcastic line like this in a lame attempt to mock me:
QuoteIs this the PCB layout your talkin about? Wow that's really kind of you :icon_rolleyes:
Should I just yank all my stuff and not contribute anything? I'm trying to be friendly and exclusively posting my transfer graphics here before releasing elsewhere. That's why I want them all in this gallery first as part of the DIY Stompboxes collection. This forum has helped me more than any other during my project. Eventually it will be released anywhere else but at my doing. The DOD pedal isn't my property at all but my artwork and graphics are mine and I should be the only one authorizing who gets a hold of them first and feel the people here get first try at it if they want to make one. If you want to post my graphics someplace else ask my permission which is proper to do. If not then maybe they shouldn't throw stones by instigating matters making it get ugly again. I hope not. This is a good neutral thread that Brymus started about a great classic pedal and all variations including clone layouts so pray some will not ruin the mood here, 'nough said.
Quote from: zombiwoof on June 04, 2010, 03:59:03 AM
a full mod to gray spec of the reissues that uses a 741 chip, but it necessitates rerouting the pins because of the difference.
The YJM308 layout graphics I posted on the first page shows how to do this. It isn't that hard but the 1458 being a dual 741 shouldn't be too off spec if you don't want to cut the traces.
"Please step back, there is nothing to see here. Thank you.
Could we please keep this thread on track ? PLEASE ,this thread is for those who wish to build a 250 type pedal and need help in the form of layouts ,ect,and for documenting the changes and revisions in design of this circuit.
Steve has every right to decide what to do with his artwork. So please no further posting about that...
Hey Bryan if you like I'll make a better version of the YJM308 PCB layout component diagram along with the Yellow re-issue now that my ExpressPCB skills are better than when I was first learning the program. Could someone post the part value differences between the YJM308 and Yellow re-issue? They both use the same identical PCB so it would be super easy to make the layouts for each one. Thanks.
Hey Steve no need to ask me,please donate whatever you feel appropriate for the thread.
I was looking at the Voodoo Lab Overdrive at Gausmarkov http://gaussmarkov.net/wordpress/circuits/voodoo-lab-overdrive/ (http://gaussmarkov.net/wordpress/circuits/voodoo-lab-overdrive/)
and I think that we could even include that in this thread due to the clipping diode arrangment,
Opinions ?
(http://gaussmarkov.net/layouts/vlo/vlo-layout.png)
Gausmarkov also did the DOD 250 and still has the Eagle files up offered to use and modify.
http://gaussmarkov.net/wordpress/circuits/overdrive-250/ (http://gaussmarkov.net/wordpress/circuits/overdrive-250/)
I really like what he has done for the DIY scene I built my Dr Boogie using his layout and PCB transfer and its now my favorite heavy OD pedal.
Anyway here is his 250
(http://gaussmarkov.net/layouts/dod250/dod250-layout.png)
I think I will search the gallery and link all the other layouts too,make this the ultimate 250 thread for comparing layouts.
I would really like to see that pictography of the 250 and YJM you were talking about doing Steve...
Hows that coming along ?
You are probably the forum expert /fanatic on the DOD 250 history :icon_cool:
Any progress progress with it ?
Thanks for reminding me about the 250 photo history. It's too late tonight but I'll post a set of photos tomorrow after work. Some are subject to some guesswork without at least pot date codes to go by but we'll start with what we have and make corrections as we go based on other's input and any new discoveries.
Here is an interesting one I just found based on the Gausmarkov version,it would be easy to make any version with the layout though.
(http://circuitworkshop.com/forum/index.php?action=dlattach;topic=430.0;attach=793;image)
Here are pictures I have. I included the outside because I found it interesting that the DOD logo changed positions. I remember throwing these into folders based on best guess at the time or the pedal owner's description. I'll split these across several posts.
1976 Gray 250 -
(http://home.comcast.net/~snmavronis/1976Dod_250-gry_07_c.jpg)(http://home.comcast.net/~snmavronis/1976Dod_250-gry_07inside_c.jpg)
1978 Gray 250 -
(http://home.comcast.net/~snmavronis/1978dod250.jpg)
1979 Gray 250 -
(http://home.comcast.net/~snmavronis/78-79dod250a.jpg)(http://home.comcast.net/~snmavronis/78-79dod250b.jpg)
(http://home.comcast.net/~snmavronis/img00031qy300x400.jpg)(http://home.comcast.net/~snmavronis/img00041j300x400.jpg)
The large diode is not original on the PCB above.
(http://home.comcast.net/~snmavronis/Bo4outside.jpg)(http://home.comcast.net/~snmavronis/Bo4inside.jpg)
The RCA 741 was only supposed to be used in the DOD 250 in 1979. Here you see versions with and without the extra 100 ohm resistor.
(http://home.comcast.net/~snmavronis/Bo4rca.jpg) (http://home.comcast.net/~snmavronis/p5_uhstyfn2m_sopcb454x400.jpg)
1980 Gray 250 -
(http://home.comcast.net/~snmavronis/gray250w100ohm3.jpg)(http://home.comcast.net/~snmavronis/gray250w100ohm4.jpg)
Here's something that I've been curious about with the gray 250. First look at this partial schematic excerpt showing the op amp output going to the diode clipping section:
(http://home.comcast.net/~snmavronis/dod250schem1.jpg)
Note that the 10K resistor R8 and 4.7uF capacitor C5 order is reversed from what other people's standard 250 schematics show. I only have it that way because it reflects the actual parts order on the gray PCB. Now another thing that goes on with part to part order on the PCB is C5 actually connects here to the diode clipping section:
(http://home.comcast.net/~snmavronis/dod250schem2.jpg)
I think (my father tells me) that electrically it's the same thing both ways. But could it make any difference maybe with a slight signal time lag or anything? Probably not but I was always curious about this. Here is my illustration representing the gray PCB layout parts pattern for reference:
(http://home.comcast.net/~snmavronis/dod250grey-pcb-layout.jpg)
Thats a cool run down. Thanks :icon_cool:
Do you have any pics of the YJM and Distortion + ?
Also what other colors and graphics have been available through the years ?
Seems I have seen a yellow 250 before, but didnt pay much attention to it.
I used to think the 10K resistor came first to act as a load for the op amp,but now I really dont think the order matters much when its in series.
Bryan, here's another pair of outside/inside photos downloaded from ebay showing probably a 1979-1980 era gray DOD 250 with a UA741 IC and the extra 100 ohm resistor:
(http://home.comcast.net/~snmavronis/!Bu3JO+wCGk~$(KGrHqJ,!iQEv1+0BTOpBMCE86HvKg~~_12.jpg) (http://home.comcast.net/~snmavronis/!Bu3J(lwEWk~$(KGrHqV,!hMEv1+0CqF5BMCE9hI,Lw~~_12.jpg)
These seller descriptions are so generic. I wish they would take the time to post the pot date codes for authenticity.
Quote from: Brymus on June 07, 2010, 09:17:04 PM
Do you have any pics of the YJM and Distortion + ?
You want some pics of the 308?!
Here's a picture found on a Japanese site showing some of the Analogman "mojo" mod with a 741 installed on a reissue DOD 250 PCB. Too bad he didn't use an IC socket and wire that jumper underneath!
(http://home.comcast.net/~snmavronis/analogman250LM741.jpg)
Quote from: Steve Mavronis on June 11, 2010, 08:11:35 PM
Here's a picture found on a Japanese site showing some of the Analogman "mojo" mod with a 741 installed on a reissue DOD 250 PCB. Too bad he didn't use an IC socket and wire that jumper underneath!
(http://home.comcast.net/~snmavronis/analogman250LM741.jpg)
Interesting, it seems there is a resistor change I wasn't aware of in the mod (R8, the carbon comp in the pic). I thought all you had to do was change the input cap and IC.
Al
Quote from: zombiwoof on June 12, 2010, 12:17:25 PM
Interesting, it seems there is a resistor change I wasn't aware of in the mod (R8, the carbon comp in the pic). I thought all you had to do was change the input cap and IC.
Yeah I saw that too. According to what comes on the pedal to get it to gray spec you'd remove the 25pF C2, change the 0.001uF input cap C3 to 0.01uF, and go at least to a 1458 (dual 741) op amp, and if you actually do the "mojo" mod to a regular 741 you'd have to do some trace and wire re-routing to compensate for the different pinout. If you did change out the op amp you should add an IC socket too.
Quote from: Steve Mavronis on June 12, 2010, 12:26:21 PM
Quote from: zombiwoof on June 12, 2010, 12:17:25 PM
Interesting, it seems there is a resistor change I wasn't aware of in the mod (R8, the carbon comp in the pic). I thought all you had to do was change the input cap and IC.
Yeah I saw that too. According to what comes on the pedal to get it to gray spec you'd remove the 25pF C2, change the 0.001uF input cap C3 to 0.01uF, and go at least to a 1458 (dual 741) op amp, and if you actually do the "mojo" mod to a regular 741 you'd have to do some trace and wire re-routing to compensate for the different pinout. If you did change out the op amp you should add an IC socket too.
I didn't think the Yellow 250 RI has the 25pf cap, I thought that's only on the YJM308(?). Maybe that pic IS the 308 (I thought they used the same board). Anyway, I know about all of those mods, what I'd like to know is what is the deal with the carbon comp resistor in the pic?. Is it a change of value, or just of resistor type?. I know AnalogMan uses carbon comps in his TS mods, I'm wondering if there is a similar resistor mod he does in this case.
Al
Quote from: zombiwoof on June 13, 2010, 02:10:48 AM
Anyway, I know about all of those mods, what I'd like to know is what is the deal with the carbon comp resistor in the pic?. Is it a change of value, or just of resistor type?
That is odd because the original grey pedals (to know knowledge) never used carbon comp resistors! It just must be marketing crap? You know, "we even downgraded the resistors to ones that are more expensive and less useful!" Maybe they can even toss some dust into the pots to make them scratchy and intermittent?
-Joe Hart
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43214&g2_serialNumber=1
On the last version with mods, the one with the many switches, what values for C9 and C10 could you recommend? Also, could you draw on the picture how exactly the switches are connected, especially SW 3 and SW 2, as there is no schematic provided and I have yet to find out how the on off on switches work =)
Best Regards
Quote from: zombiwoof on June 13, 2010, 02:10:48 AM
I didn't think the Yellow 250 RI has the 25pf cap, I thought that's only on the YJM308(?).
Both boards have a C2 in the feedback loop. Maybe the yellow reissue has a different value cap there?
Here is some info found on the net about reissue yellow vs yjm308 that I'll condense here. I'd have to see a side by side parts comparision to see which one overall would be less work to mod to grey specs:
QuoteThe YJM is the same circuit as the original "Yellow" Dod 250 but with a .001uf input cap (vs. .01uf on the original). Also, the reissue 250 has a 100k resistor feeding the clipping diodes; the original and YJM have a 10k.
you can mod the re-issue yellow and the yjm308 to grey specs! - change the .056 cap to .047 - remove the 25pf cap - change the 100k resistor to 10k - change the .001 cap to .01 - remove the 4558 chip,install a socket and a 1458 chip [its basically a dual 741]
Heres the specs of the yellow reissue late 90's model, Board number 80-6211-A (Please note some of the resistor readings could be inaccurate as it was really hard to tell White from yellow plus im not the best reader of the codes).
R1. 4.7K
R2. 1M0
R3. 10K
R4. 100R
R5. 22K
R6. 470K
R7. 22K
R8. 100K
D1 & D2 CANT READ THE LITTLE WRITING.
C1. 2A 563 J Large green
C2. 25J SMALL ORANGE CAP
C3. 2A 103 G Medium sized green
C4. 10uF Black
C5. 4.7uF 35V Black
C6. 2A 102 K Medium sized green
U1. KA4558
522C
(this is exactly how its written on the chip with the other numbers and letters underneath.)
P1. C500K with the ink code 9739
P2. W100K " " 9807
That explains it, that resistor is R8, which has to be changed to 10k from 100k. The carbon comp is just an AnalogMan thing, he always seems to use carbon comps in his mods, it has nothing to do with what was in the originals. It just stood out in the pic, as it was the only carbon comp there.
Al
Quote from: tednet on June 13, 2010, 11:00:16 AM
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43214&g2_serialNumber=1
On the last version with mods, the one with the many switches, what values for C9 and C10 could you recommend? Also, could you draw on the picture how exactly the switches are connected, especially SW 3 and SW 2, as there is no schematic provided and I have yet to find out how the on off on switches work =)
Best Regards
On SW2 the center post (SPDT) is connected to C6 (should be .047uf not pf) then the two outer posts would be connected to C9 and C10 this would be to add them to C6 so C6 is your smallest value cap and then the other two caps are added seperatly to make higher values.
As far as values, the larger the cap value (combined or single) the greater the bass response will be.
A good ide IMO would be to make C6 smaller than stock so that adding C9 would equal the stock value then adding C10 would make the combined value rather larger than stock.(sockets for all 3 caps here is a good idea, so you can find the values you like most)
To start you could try making C6 and C9 both .022 uf and make C10 .1uf SW settings = stock,(less bass than stock=middle) ,more bass than stock
Or another good combo would be C6 .047uf C9 .022uf and C10 .047 - .1uf SW settings = more bass than stock,(stock=middle),even more bass than stock
SW3 is similiar (SPDT) the center post would connect to the unused pad on the top most trace.The outer two posts would connect to the unused pads at D5 and D3
If you use an ( on,off,on ) type switch then the middle postion would be a clean boost (no diodes in use) ,and all the clipping would come from the op amp.
If you use an ( on,on ) switch then you would just be changing between the two sets of diodes.(one set of 2 diodes the other a set of 3 diodes)For two different clipping sounds.
LEDs , 1n914/4148 , small zeners , and 1n34 or other Ge types are good choices to experiment with (use sockets if you arent sure which to use)
(I drew in LEDs for the set of two and 1n914 for th eset of 3 as these are my favorites for this set up.)
SW1 Connects to the unused pads by D6 it is a simple (SPST)(open or closed) switch it closes to short out (remove) the second diode in the pair that are in series.(D5+D6)
With the switch closed (shorting out D6 ) you have symetrical clipping.
With the switch open the second diode (D6) is in series with the first (D5) and you get asymetrical clipping.
I hope that explains it well enough ,if not I will try to draw a pic for you 8)
@Carbon comp resistor
Isnt that the 1M resistor in the FBL ?
Perhaps he thinks it will add some of the distortion that carbon comps are known for in tube amps to the distortion of the pedal.
If so he hasnt read the GEO article which states the voltage needed is way higher than that present in a FBL of an op amp.
At any rate a sound test would be in order to see if you can notice any flavouring worth keeping ,or if its just adding more noise.
It still got you guys talking though ,so it at least has shock value if nothing else :icon_mrgreen:
Thanks Brymus, I can't express how grateful I am for everything =)
Quote from: Brymus on June 13, 2010, 06:01:47 PMAt any rate a sound test would be in order to see if you can notice any flavouring worth keeping ,or if its just adding more noise. It still got you guys talking though ,so it at least has shock value if nothing else :icon_mrgreen:
Just some obvervations relating to noise and tone with 250 circuits and component values used over the different versions of this pedal. The only comparision I have first hand is between my stock YJM308 and the late 70's grey clone I built, of which you would expect not just mine, but anyone's such clone to sound pretty close to the gray pedal it is modeled after. So for the sake of discussion I'm going to equate everyone's "gray spec" clones with the original gray 250 itself and assume they all sound the same if built from the same component values. I'll use the parts labeling of the YJM308 to make a comparision list between it and a late 70's gray spec clone:
| Component | Late 70's Gray 250 | YJM308 |
| U1 (Op Amp) | LM741CN | KA4558 |
| R1 | 4.7K | 4.7K |
| R2 | 1M | 1M |
| R3 | 10K | 10K |
| R4 | 100 | 100 |
| R5 | 22K | 22K |
| R6 | 470K | 470K |
| R7 | 22K | 22K |
| R8 | 10K | 10K |
| P1 (Gain) | 500K Reverse Log | 500K Reverse Log |
| P2 (Level) | 100K Audio | 100K Audio |
| C1 | .047uF | .047uF |
| C2 | N/A | 25pF |
| C3 | .01uF | .001uF |
| C4 | 10uF | 10uF |
| C5 | 4.7uF | 4.7uF |
| C6 | .001uF | .001uF |
| D1 | 1N4148 | 1N4148 |
| D2 | 1N4148 | 1N4148 |
In later posts I'll update this table with more columns to include the other 250 variations.
The first thing I noticed between a YJM308 and a gray 250 when playing through it is tone. The YJM308 sounds more like a treble booster whereas a gray 250 has more midrange tone. Does anyone have tone difference experience with the reissue yellow 250 and a gray spec clone? The other thing I noticed is noise output. The YJM308 is very noisey at higher gain levels. My clone 250 is not as noisey. I don't have a scientific measurement but I see a difference with my Boss NS-2 Noise Suppressor pedal. It has a threshold knob with a red LED that lights when noise reduction turns itself on to eliminate the hiss. I can use less noise reduction with my clone (with threshold set at 2:30 position vs almost 5:00 with the YJM308) so my note sustain is longer before it decays and cuts off. With the YJM308 there is a strange and annoying "sizzle effect" heard the longer you hold a note before it decays.
Here are some YJM308 PCB pics:
(http://home.comcast.net/~snmavronis/yjm_pieces(cropped).jpg) (http://home.comcast.net/~snmavronis/yjm_open(cropped).jpg) (http://home.comcast.net/~snmavronis/yjm_pcboard(cropped).jpg)
Quote from: zombiwoof on June 13, 2010, 04:27:24 PMThat explains it, that resistor is R8, which has to be changed to 10k from 100k. The carbon comp is just an AnalogMan thing, he always seems to use carbon comps in his mods, it has nothing to do with what was in the originals. It just stood out in the pic, as it was the only carbon comp there.
Interesting about the carbon resistor mod, but on my stock YJM308 and the large PCB picture in my last post R8 is still a 10K value with 5% tolerance - brown-black-orange-gold. I'm not sure where that forum post that I found and quoted got that 100K info. Maybe it's a typo on his part?
Well that throws my idea out the window ...
I thought it was the feedback loop resistor.
Zombie even explained that a post above :icon_redface:
I should wear my glasses when reading, DUH
That is the place likely to have the highest voltage swing signal wise though. AFAIK (could be wrong)
So I guess, why not, a 10K isnt as likely to have as much noise as a 1M.
Quote from: tednet on June 13, 2010, 06:39:00 PM
Thanks Brymus, I can't express how grateful I am for everything =)
Hey I am very glad to help : :icon_mrgreen:
Its nice to pay forward the generosity I have recieved in the DIY circle,especially here. :icon_cool:
Quote from: Steve Mavronis on June 13, 2010, 07:23:27 PM
Quote from: zombiwoof on June 13, 2010, 04:27:24 PMThat explains it, that resistor is R8, which has to be changed to 10k from 100k. The carbon comp is just an AnalogMan thing, he always seems to use carbon comps in his mods, it has nothing to do with what was in the originals. It just stood out in the pic, as it was the only carbon comp there.
Interesting about the carbon resistor mod, but on my stock YJM308 and the large PCB picture in my last post R8 is still a 10K value with 5% tolerance - brown-black-orange-gold. I'm not sure where that forum post that I found and quoted got that 100K info. Maybe it's a typo on his part?
If the stock R8 value for the 308 is already 10k, then I don't know what the explanation is for the carbon comp in the picture. Of course, we don't know if that is something that AnalogMan did or not, the owner of the pedal could have done it himself. I'll have to check my 308 and see what it has there.
Al
I'm trying to update my model year comparision table of parts used in the 250 and searched through my collection of gut shots for an example of a 1977 gray. It is supposed to not have the 470K (yellow-violet-yellow-gold) bias resistor value coming off pin 3 of the 741 op amp. Instead it should be 510K (green-brown-yellow-gold). I found these images of the same unit that has either a 510K or 570K bias resistor, depending on the "brown or violet" color shift of the image. But the pot date code says this gray is at least from the 15th week of 1978:
(http://home.comcast.net/~snmavronis/1978gray3.jpg)
(http://home.comcast.net/~snmavronis/1978gray9.jpg)
Does anyone have a clear PCB image from a 1977 model gray that I can read the resistor color codes of, so I can update my table? I can't read perf board or vero layouts to tell what connects to what. Even some PCB layouts of a 1977 model include modifications so I can't take anything but the real thing as reliable.
Here is a resistor color code calculator webpage to make life easy:
http://www.hobby-hour.com/electronics/resistorcalculator.php
Quote from: Steve Mavronis on June 13, 2010, 07:02:30 PM
The first thing I noticed between a YJM308 and a gray 250 when playing through it is tone. The YJM308 sounds more like a treble booster whereas a gray 250 has more midrange tone. The YJM308 is very noisey at higher gain levels. My clone 250 is not as noisey.
The input cap makes all the difference (and the IC, but not so much to my ears...) - I made a grey one with an input cap switch - that is very useful!!!
hear some samples!!!
Gain at min. (http://renegadrian.altervista.org/dod/250-min-gain.mp3)
Gain at max. (http://renegadrian.altervista.org/dod/250-max-gain.mp3)
The same licks with the original 308
Gain at min. (http://renegadrian.altervista.org/dod/original-308-min-gain.mp3)
Gain at max. (http://renegadrian.altervista.org/dod/original-308-max-gain.mp3)
Anyway, I'd like to post this pic of my layout...
(http://renegadrian.altervista.org/dod/24.05-28sm.jpg)
Quote from: Renegadrian on June 15, 2010, 09:30:19 AM
The input cap makes all the difference (and the IC, but not so much to my ears...) - I made a grey one with an input cap switch - that is very useful!!!
hear some samples!!!
Thank you very much for the samples comparisons! What input cap values are you using?
Quote from: Steve Mavronis on June 15, 2010, 10:37:35 AM
Quote from: Renegadrian on June 15, 2010, 09:30:19 AM
The input cap makes all the difference (and the IC, but not so much to my ears...) - I made a grey one with an input cap switch - that is very useful!!!
hear some samples!!!
Thank you very much for the samples comparisons! What input cap values are you using?
Basically it's a grey that uses the same BOM you listed above, so C3 (input cap) has .01uF and .001uF on a dpdt.
@ Adrian ,Nice,what amp and guitar are you using ? so people know for comparison purposes.
In the samples with the input cap on a switch.
Are you switching PUs ? I hear four different sounds.
Its amazing how much a difference the input cap can make,not just treble wise but mid and total loudness wise as well.
I am undecided, ??? But I think I like the fuller sound better,it would definetly cut through a mix better if that were a deciding factor.
I think after hearing your examples I would need at least 3 settings,maybe .001 , (.0033/.0047/.0068) not sure on the middle one , and .01
And Yeah thanks for posting that Adrian,thats a good idea and good to have for this thread.
Some more soundclips might be helpful to people trying to decide if they should build the pedal or not ?
nice to hear a sample of it adrian......more gainy than i thought it would be...
i'd still like to hear some malmsteen riff/licks with it though!....to see/hear its full potential...
anyone?...steve?...
rob.
The samples were recorded without an amp, signal went guitar (strat) -->pedal -->Zoom pedalboard for a touch of reverb -->input of the Creative soundcard and recorded with Audacity on a Kubuntu machine.
You hear 4 sounds because that pedal had the diode switch too, so 2 switches=4 sounds.
As for the diodes, you can clearly hear how the red LEDs add volume and "air" to the sound - my fav. mod to all pedals is to have the clipping choice!!!
Well, I gave it away now...Do you want some original 308 samples?! :icon_smile:
yeah that'd be good..cheers.rob
edit:
@steve.great..look forward to them ....rob.
Quote from: deadastronaut on June 15, 2010, 05:06:55 PM
i'd still like to hear some malmsteen riff/licks with it though!....to see/hear its full potential... anyone?...steve?...
I'll trying recording a couple Malmsteen licks soon with my '79 straight 250 gray spec clone. I'm practicing some stuff so the playing isn't too bad or distracting. Working on excerpts from Majestic Blue and some other Yngwie tunes plus some rhythm riffs. Deciding if I should mic my lowly MG4 (new series) Marshall solid state amp (the pedal really does make it sound more tube-like) or directly into my PC using my Line6 Toneport GX interface and Riffworks or Gearbox software. I have Audacity too. Was hoping to get something from Dean Cascione using the twin copy I gave him (he volunteered a donation of $50 to cover parts cost plus shipping) of my clone 250 pedal and his Voodoo tube amp, but nothing yet.
Quote from: Renegadrian on June 15, 2010, 05:08:08 PM
The samples were recorded without an amp, signal went guitar (strat) -->pedal -->Zoom pedalboard for a touch of reverb -->input of the Creative soundcard and recorded with Audacity on a Kubuntu machine.
You hear 4 sounds because that pedal had the diode switch too, so 2 switches=4 sounds.
As for the diodes, you can clearly hear how the red LEDs add volume and "air" to the sound - my fav. mod to all pedals is to have the clipping choice!!!
Hey thats awesome,thanks for sharing !!!
Especially since I posted layouts with clipping options ,its especially nice to have some clips of it in action.
I agree I like the LED clips better too :icon_twisted:
What I really liked was the blind comparison,I had no idea the sound change was from clipping changes....
I couldnt even do any Malmstien licks (not that I would want to post at least) ,so if you guys can ,then super !!
Steve I think which ever sounds better to you,or what shows the pedals sound the best is what you should use.
It will probably color the input of the MG series amp some,but not everyone has a tube amp so this could be good as a reference for its non tube use.
IMO the pedals sound as used by Malmstien is also due to the tube amp breaking up under the high level of voltage swing from the pedal.
RG has written articles about this (Rangmaster article,applies here too) and how it effects the triode when being subjected to such a high level of voltage swing on the amps input.
Yeah nothing would be better than to use an overdrive on a tube amp but a gray spec 250 definitely sounds better than a YJM308 on my solid state. Very surprising to me. BTW, the new MG4 series amps that came out last year are worlds apart from the old MG amps. I know because I had one of the older series too! Just watch the Rob Chappers video demo of the new MG15FX which convinced me to try one again. It's supposed to be using analog circuitry instead of digital for the tube amp emulation. I guess the extra effects are the only digital part. My other solid state is a Roland Cube 20X and the new MG series 4 sounds better than the Cube (it also sounds better than my old MG) which I don't use any more. Me saying that won't change the minds of MG skeptics. Back to topic, I don't know why Yngwie choose to alter the YJM308 specs slightly from true gray spec giving it a higher treble output. I guess it sounds good on the amps he uses though.
Quote from: Steve Mavronis on June 15, 2010, 06:45:00 PM
Back to topic, I don't know why Yngwie choose to alter the YJM308 specs slightly from true gray spec giving it a higher treble output. I guess it sounds good on the amps he uses though.
I would say that "playing loud" has taken a toll on his hearing. That and age can cause the high frequencies to start to diminish. Also, his new Duncan pickups are a little "gainier" and the neck pickup is a bit thinner/trebley. But he's still pretty good, I think.
-Joe Hart
Quote from: Steve Mavronis on June 15, 2010, 06:45:00 PM
Yeah nothing would be better than to use an overdrive on a tube amp but a gray spec 250 definitely sounds better than a YJM308 on my solid state. Very surprising to me. BTW, the new MG4 series amps that came out last year are worlds apart from the old MG amps. I know because I had one of the older series too! Just watch the Rob Chappers video demo of the new MG15FX which convinced me to try one again. It's supposed to be using analog circuitry instead of digital for the tube amp emulation. I guess the extra effects are the only digital part. My other solid state is a Roland Cube 20X and the new MG series 4 sounds better than the Cube (it also sounds better than my old MG) which I don't use any more. Me saying that won't change the minds of MG skeptics. Back to topic, I don't know why Yngwie choose to alter the YJM308 specs slightly from true gray spec giving it a higher treble output. I guess it sounds good on the amps he uses though.
The reason the YJM 308 is altered from the gray spec is that DOD was using the 4558 chip instead of the original 741 (and the same board as the Yellow reissue), so they just tried to get it to sound like his old pedal by tuning those components instead of doing a true reissue. That's why they have the 25pf cap on there to try to make the higher fidelity 4558 sound more like the 741. As for the input cap difference, that also is probably because the original .01uf value didn't sound right with the 4558 (and didn't sound like his old 250), so they changed it to .001uf. They actually were using Yngvie's old 250 as a reference point for the sound of the YJM308. I don't know why they didn't actually try to do a true reissue, in my mind that would have been a better solution, but by doing that they would be admitting that the "reissue" they already had out (yellow 250) wasn't correct.
It turns out the the 308 doesn't actually sound like the gray 250's, but probably it sounds like his at the setting he always uses, and that was good enough for him.
Al
I updated my Excel spreadsheet (since I got details from a 1982 Yellow 250 Overdrive) comparing components between various DOD 250 Overdrive versions. Does anyone wish to make corrections or add the missing info to this? The blank values are un-verified right now until we get more info:
(http://home.comcast.net/~snmavronis/dod250comparision.jpg)
This brings up a question. A guy on Ebay was recently selling a reissue yellow 250 from the 90's that he said was made in the U.S., not China. Did DOD do a run of the reissues in the U.S. before the Chinese production?. I know it's possible, but I've never heard of them. I also know that Digitech did something like this with some pedals like the Bad Monkey, there was an initial run of U.S.-made pedals, then production went to China. I have a U.S.-made Bad Monkey myself. So has anyone heard of this American reissue 250 from the 90's?.
Al
OK then it looks like the only differences are the IC's and pot tapers.
Maybe the input resistors. And the 100r resistor.
I was also under the impression some years had 4.7uf electro and some had 10uf electros ,
any idea what years had the different values? Or is this not true ?
Correction notification for anything in error is welcome and I'll update the spreadsheet graphic accordingly.
Here's a schematic graphic I updated for a 1982 Yellow DOD 250 Overdrive that I'll add in this topic while I'm here:
(http://home.comcast.net/~snmavronis/schematic1982dod250wiring.jpg)
A friend over on TGP sent me these nice shots of the 1976 (or 1977) gray DOD 250 he has! The chip says 76 so it is at least that year or later and it's missing the extra cap and no DC jack:
(http://home.comcast.net/~snmavronis/MVC-005F(800x600).JPG)
(http://home.comcast.net/~snmavronis/MVC-007F(800x600).JPG)
(http://home.comcast.net/~snmavronis/MVC-011S(640x480).JPG)
hi, i haven't followed this thread but i noticed the blue electrolytic in pics above is 6.3v 22uF.
guess it's 63 and not 6.3 - the pic is not so clear tho'
Could you show me how you wired the input cap switch? I also plan on putting in a diode switch. think they sound great w/ no diodes too.
By the way 308's are only $30 delivered on Amazon. I bought three. I'm going to put the switches in them, give two away to friends for Christmas and keep one.
That reminds me I should either buy another cheap YJM308 to to a quick mod with a dual 741 chip and a couple cap change plus add an LED, or just mod the one I already have. I was debating keeping that stock in case it's collectable 10 or 20 years from now.
jerry garcia used an mxr dist + for leads/solos for most of his career. ?!? yep. script logo with germanium diodes i believe.
basically a dod od250 with different bias resistors... maybee a few other differences?
just thought that was odd... yngwie/jerry ??? could you find 2 guitarists who are more different...
Both pedals sound a bit different. And maybe they have used them in different ways: With Ge-diodes you get more distortion and less output level, so I guess that Garcia used the pedal to produce a lot of distortion itself. Malmsteen seems to use it mainly as a dirty booster. And off course, the rest of their equipment, fingers, playing style etc is different.
hey quick ? i breadboarded the 82 schem. on p1 3 hookes to the .047. 1 goes to ground. what does 2 hook to. ive built this before but dont rem where it goes.
Quote from: roseblood11 on January 26, 2011, 04:14:56 PM
Malmsteen seems to use it mainly as a dirty booster. And off course, the rest of their equipment, fingers, playing style etc is different.
Yes the 308 alone does give you YM sound but it hasn't got all the gain needed to get his TM sound...
Basically it gives a good boost at his 50w Marshalls, adding a little on the treble sound. I guess he doesn't use it anymore, at least in studio, as his last recordings spot a dark and muddy guitar sound...I love him as a musician, but he's an awful producer...I listened to a lot of newcomers' demos that sound better than YM last records!!!
I agree with you about the bad studio mix on Yngwie's last album. Seems too heavy with the bass EQ to me. He reportedly used a prototype of his new signature Marshall YJM100 amp, which has a 'boost' overdrive built in. They are a little vague about what it actually is, just saying it's to Yngwie's spec from his YJM308 overdrive. I find that hard to believe they would integrate the exact DOD circuit basically cloning it like we do. But they won't identify it by name and the schematic isn't protected so I guess they have the same freedom as we do. But I like the tone of the gray 250 more than his 308 anyway. Can't wait until someone gets the amp and shows us a gut shot of the overdrive circuit. I don't think this is responsible for the bad production sound of the album. It's in the mixing. Very soon Marshall is promising a new demo video of the YJM100 with Yngwie himself playing it using his Strat to show off the features. Then we can get a good assessment of what overdrive is in it.
This is interesting. Today after work I compared my gray 250 clone and the YJM308 mod to gray spec side by side. One thing I noticed was that at half way the level (volume) knob setting the YJM308 is louder. I found the reason why. My 250 clone uses a level pot value of A100K which is A for Audio Taper. The YJM308 uses a W100K for its Level pot. I've only seen A=Audio, B=Linear, and C=Reverse Audio log pots for sale online. I was trying to figure out what the W stood for. This is what I found:
If you look at this pot taper comparison graphic below you can see in the bottom left graph when the W taper is at 50% rotation it is at half the total volume range. In the top left graph the A taper has to be at roughly 75% rotation or so to have equal volume output.
(http://www.keikocorp.co.jp/images/TBM_resistance_taper.jpg)
Of course you can match their volumes by ear but now I know why.
I modded my DOD YJM308 Overdrive to late 70's gray specs. Removed stock KA4558 chip and replaced with socketed LM1458N (dual 741 op amp), removed C2, and replaced the 0.001uF input capacitor C3 with a 0.01uF value per spec. I used fine braid size #2 solder wick and it worked so good de-soldering the parts that they literally fell out of their holes. Simple and done in less than 30 minutes!
(http://home.comcast.net/~snmavronis/yjm308mod1458pcb.jpg)
I finished off the mod with original DOD style fluted knobs! Sounds freaking great now. I decided not to cut traces and re-route wires just to use a single 741 chip. The 1458 op amp has two 741 circuits inside and using one of them so it is technically still the same. Comparing noise levels to a gray 250 clone I can't hear any difference to make it worth doing the so-called 'mojo' mod.
(http://home.comcast.net/~snmavronis/yjm308mod1458box.jpg)
I've been meaning to do this for some time. Only thing 'optional' I could add is true bypass 3PDT footswitch, LED, and Boss style power jack, and maybe re-decal it to say YJM250.
Something I've always wondered about: What were the 2 part holes (near the bottom on the old 250 PCB in the photo below) originally used for? I think there is a clue. Most everyone knows the 250 was based on the 70's MXR Distortion+ circuit. It's virtually identical except for component values, and one extra part! On the Distortion+ PCB there is an extra 0.001uF cap connected right after the input pad (before the 0.01uF input signal cap) going to ground.
On the 250 this is missing, with the apparent empty pad holes for it located in between the 0.01uF input cap and 10K resistor, going to an empty ground pad hole. Funny after all this time I only realized what this was probably for after reading an Arctic Fox Audio blog article (http://www.arcticfoxaudio.com/blog/articles/7/reducing-noise-in-the-mxr-distortion)
about "Reducing Noise in the MXR Distortion+" that caught my eye. I'm interested in trying out the author's technique for reducing noise by half. It seems that to achieve this he decreased the resistor values and increased the cap values to preserve the frequency response, but the pedal didn't sound the same at all. But he got that corrected by changing this 'input cap to ground' back to its original value.
In the case of the 250, or any circuit, would the actual placement of this missing cap matter if it would be located 'before or after' the input signal cap? I might try this on one of my extra clone boards and if it works make a new modified noise reduced version. Of course the begging question is why DOD made their PCB including these part holes and why didn't they actually use it?
(http://home.comcast.net/~snmavronis/p5_uhstyfn2m_sopcb454x400.jpg)
Hi guys, hoping someone can help an old fella out... Apologies for bringing up an old thread... I am hoping to put together a grey spec 250 like I used to own back in the day. I put together the layout at the top of front page provided by Brymus (without mods) Has this layout been verified by anyone else? I'm not getting anything, but I don't trust these eyes so much anymore... I've put together quite a few pedals and amps over the years so I'm relatively confident.. Great thread by the way for a very under-rated pedal!!
Herb
Hi guys! I've build this great pedal based on this layout:
http://www.sabrotone.com/?attachment_id=2467
Is it possible to mod the flabbiness of the lows?
Also is it normal to put the Level around 3 o'clock to match the bypass signal? The level is too low.
Here is a demo with the pedal without any modifications, build strictly on Sabrotone's layout.
https://soundcloud.com/diminalbantov/guitar-rig-5-marshall-plexi-50-diy-250-boost
I do want to reply! no need to start a new thread? :)
I have never heard on of these in person..or have I lol ? what guitarist uses one on what song? I might try to make of of these as i have the parts here on hand at home
spent more time with this circuit over the last year . th customs sells a OD 67 pcb with all of the Brian Wampler mods from the article featured in premiere guitar . i built my own version of this Wampler mod 250 and auditioned those mods to chagrin, as ultimately i found the 250 is best served stockish but with custom clippers.
i wanted to mention something i found which i read in this thread about the 25pf C2 as it is listed on the Marvonis chart (Thanks Mr.Marvonis ) . if one looks at the DOD schematic , it shows a 120pf capacitor in the feedback loop of the op amp , so this is the feedback capacitor .
i found thru my experimentation nasty loud HOWLING feedback if i was running the circuit outside of a chassis with much RF interferance / oscillations due to longer runs of unshielded test rig wire etc , it was of utmost importance to utilize this capacitor to avoid feedback and howling when the gain/volume knobs are above noonish . one can merely run a 47pf-120pf comfortably without worrying about cutting into the guitars treble frequencies too much . in the past when i have made these circuits on a vero layout i typically just prema-install a cap with a value of 100pf here , to feel nice about myself as i also realize this is nice to have even when using the slow slew rate dirty stinky hated noisey 741 . not to contradict any one , but in my experience i do utilize that capacitor no matter what ic chip i choose to install to enjoy stability / noiseless operation .
op amps matter in this instance. to my ear ANY 741 is the winning choice . this is especially evident when running the circuit sans clippers as this the distorting on its own 741 chip is doing its job and thats where the magic sits in this circuit , using the right clippers for your rig / ears and most importantly using a slow slew rate nasty old 741 .
i do not intend to contradict folks but in my testing i heard differences that were percievable to the point of me choosing one chip over another , they are not large enough to seek these out , but i will say the 741 in every itteration was superior to evry other chip that we ran .
the metal can ray741 actually does sound a bit less raspy and has a slight more bit of oomph between the 741ua chips i pitted it against but todays testing show the authentic lm741cn vs the metal can circa 79 ray741 was in fact the top peak sounding winner for just a smoother less raspy and having that special something in the way the distortion sounded with chords and single note playing as we did a repetitive series of tests with different phrasing /chords and notes to fully hear everything we could think of and be fair . the metal can has something undefinable but i would call it tightness and a smoother more pleasant break up .
chips to avoid -
using a lm308n /tlo71 in it and its much more pristin-ie and harsh ice pickie fizzish distortion as it lost its magic , which is quickly regained when the 741 chip is in place . testing done with high output humbucker guitar >DoD250(powered by fresh 9 volt ) >jc 120 clean channel eq maxed , bright off and also on , low channel input .
as far as clippers go , two red 3mm leds are where you start. one ear which i would say is trained ( you may have some of his music in your collection) ended up choosing a red 3mm led combined with a 1n4148 .
using the 250mod w/two red led's and setting this circuit "nooned" is my favorite way to play ,its always on unless i am going for a high gain deal, and man it sweetens everything , its very uncompressed clean and only grits when i dig in with a very unique grit that fits on top of the clean not like that unpleasent effect of a lm386 set to low gain . this raspy distortion does sit above the clean but it fits and belongs as one , feeling so pick responsive and also sounding natural its something i have yet to find in any other circuit _ (this as described is only obtained using two 3mm red clippers and nooning the controls)-
typically most folks run this circuit much more like a dirtbox with diodes installed instead of leds , or if they are using leds they crank thegain higher ... i have to admit this was a mod gone bad that was on my board and i stumbled on it literally kciking the mod switch on accident then going wow wtf is makin that ?> lol .
i recently found using a single (or two) led and then a 1n4148 diode it really shines as a truely transparent or do no wrong med gain od when we again set at noon as well . it does "nothing bad" as one very valued ear put it .
i am going to be spending time attempting to pair an led with a diode or some new perfected combination of clippers as i have yet to even mossfet ... but my goal is to get closer to flexible overdrive that does the odball two leds set nooned is really more subtle trick that i like very much / have been using this for years now as it is my favorite most used build ,and then having the mod switch convert this to the other idea of a more pronounced overdrive . so all time wasting and path searching aside , one could just vero up a stock 250 , maybe boost the bass cap (.047uf to a .22uf per mark hammer "improve led clipping response in a led mod 250" idea quote ) use a 741 chip , then throw two red 3mm on one side of a dpdt and a1n4148 / 3mm red led on the other and be just deal with a volume difference .
the idea of having a Mod switch that one actually chooses to engage and use the other setting would literally be a first as i have to admit in most cases the mod switch is an embarrassing redundancy that is always left set to the right (or left) . i am hoping to go thru some componants and perhaps improve upon the combo i mentioned which was two red 3mm leds set facing with the anode / cathode properly aligned and then the 1n4148 was reversed in between the two . this was an error , but the guy loved it ,and asked for a 100 percent clone as a back up . ha . so i am going to be looking into that and perhaps create something for myself .
as far as the wampler mods and every other mod for this circuit , every single thing i have tried (exception of using led clipper or led combined with a diode and then using the 741 chip) has taken the circuit in a direction i felt was opposite from what i really love about it . what is that ? use a 741 , and a single 3mm red combined with a 1n4148 and you will know for yourself . if you love that consider the double 3mm red led , although i am on a path to experiment for something different as far as the dual led clipping goes .
read up and see what the pros techs and experts say about the 741 chip " why would any one dream of using this outdated turkey dirty stink chip that is a dirty bastard that even distorts - - - - um may i have one of those please as i am building a distortion ?
additional harshness and noisy noise can be tamed with the 0022uf cap placed to ground after the clippers as shown in the grey spec layout .
if one is using led clippers Mark Hammer mentioned to consider modding the .047uf (c1) bass or input cap to a .22uf - something i am considering but with the led mod i use i never set the gain more than noon , i am happy with the clipping ,still i would like to hear the mods / am curious and feel the time is well spent as i have such a huge spot for this circuitin my heart . so i should really try this as well as changing the gain by a resistor swap tied in with the control . - MHammer - stuff from another thread - additional harshness and noisy noise can be tamed with the 0022uf cap placed to ground after the clippers as shown in the grey spec layout .
TLDR ,
you HAVE to use a 741 chip or kittens will perish ,
socket the clippers, try 3mm red leds , or try 3mm red w/ 1n4148- (2 leds = less compressed more open . Led/diode combo is less subtle but natural od tone with "no bad"
use a feedback cap or C2 (on the marvonis chart) c2= 47pf or more up to 120pf) to avoid oscillation
if you dig the led clipping butneed moar consider mark hammers comment(s) about uping .047uf to .22uf for more clipping from LEDs - there is more on this from Mr H ....