Roland - AD-50 ( Double Beat )  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Dan N
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Post by Dan N »

Roland did redesign the wah part at some point. They went with the crybaby style mechanics and changed the circuit. The old pcb is 052-026 and the new is 052-026A. The bottom left greenie is .01, the other greenie is .0068. Orange drops are 0.22. The two electros are 10/25. There is a 22K resistor hiding to the left of the big orange guy. Transistors are 2SC1000GR and 2SC828R. The fuzz did not change other than the 50KA Intensity pot AG mentioned.

Of course, the blue switch in the photo is a replacement.

Edit- The wah pot has Cosmos 100KA 1973-1 stamped into it so maybe this is an earlier version.
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ad50b2.jpg
ad50t2.jpg
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Post by RnFR »

i just noticed that my layout is missing a trace cut under R8. i'll fix it when i get a chance.


as soon as i get my new shop together i think this is going to be one of the first builds i do. i really want one of these guys- the fuzz sounds great!.

and i want to get this layout verified!
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Dan N
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Post by Dan N »

The input of Q2 only connects to the 2K2. You've mistaken that crossed path of the 47pf for a connection. Hang in there!
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Post by RnFR »

Dan N wrote:The input of Q2 only connects to the 2K2. You've mistaken that crossed path of the 47pf for a connection. Hang in there!
thanks for that! looks like i've connected the 47pF to the base of q2 instead of the collector. should be an easy fix.

anything else you see, feel free to point out. i'm actually in the middle of moving right now- just taking a break- so i can't fix the layout yet. but i'll get to it asap.

thanks again. cheers!
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Post by RnFR »

layout amended. move not finished! [smilie=new_microwave.gif]
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Post by Whoismarykelly »

Anyone had a chance to verify the layout?

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Post by RnFR »

not yet, man. i've moved, but there is TONS to do, so my building has been put on hold. just get to mess around with my breadboard a little. all the while my killer new shop in the basement sits unused. [smilie=a_damnit.gif]
this'll be one of the first i get to when i get a chance.

care to give it a shot?
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Post by Whoismarykelly »

Layout is verified. If I were building another I would scrap the rotary and wire up only Out 1. The other two are either all bass and no high end which is completely muffled and extremely bright, thin and harsh. Its only of those super compressed bottom end fuzzes so I wouldn't expect much in the way of clear bar chords or anything like that. Sounds cool though.

Image
Image

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Post by RnFR »

[smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif] [smilie=a_goodjobson.gif]
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Post by RnFR »

what tranny's did you use? i just realized last night that it's the wrong pinout for 2sc828's.
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Post by Whoismarykelly »

Oddly enough I had some bc828s I was originally going to use in a BeeBaa and I just added some wire insulation to the leads and bent them to make them work. They actually sound better than the 3904s and other stuff I tried.

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Post by RnFR »

cool. i'll adjust the layout when i get a chance. the pinout on those trannys totally slipped my mind. i'm realizing that a lot of those old japanese transistors have strange pinouts.

thanks again for the verification!
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Post by BeesKnees »

Cool project. I built a double beat clone last year and I thought I did something wrong because it has so much gain. I bought one off of ebay(for way too much money) to A/B and they sounded exactly the same. I used some NOS Toshiba 2SC1815-GR's that I got from Small bear. I put a input volume knob on the side which cleans it up quite nicely.

The bass/counter clockwise side of the switch is labeled as the sine wave, full/middle is square wave, and the thin/clockwise side is triangle wave.

It's a cool pedal that sounds great with bass. Bar chords sound great with the volume down on the guitar but get really muddy with the guitar on full. It's my favorite fuzz pedal.

Thanks for posting your layout, RnFR!

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Post by dmk2113 »

To resurrect this thread - I recently built one of these on perf based off of the schematic (veroboard is unavailable in Japan where I live) and while it's not the most elegant thing to look at, I figured I would share the love. This is also my first post!

As soon as I figured out that this was the same pedal that Carrie Brownstein uses on Sleater-Kinney's The Woods I had to have one and I've sold off all my other not-my-tonebender-fuzz pedals since I built it. It's like going to filthy raunchy fuzz heaven.

Also, if anyone ever decides to build one of these in the future, I have come across a batch of NOS 2SC1000s that I can sell for cheap (shipping would have to be from Japan, but I can send it via letter post and I can be paid in dollars).

Red wires are top-of-board jumpers. I am sure there is a way to do this more compactly, but I am bad at these sorts of things.
DoubleBeat.png

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Post by jzilla »

i think i'm going to try to make this one. i've searched around for the 2sc1000 and 2sc2240 but am having a hard time finding either. can anyone point me in the right direction?

also, is there a layout of the wah section anywhere?

thanks!
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Post by glops »

Me first post here. Just wanted to thank you fellas for posting this one. I gots the D beat on bread board now. It sounds totally fucking killer. gonna perf it right now. Love the beast....

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Post by glops »

I perfed this on Saturday night and got it boxed. It is a killer massive wall o fuzz. Tonight I added the tone options. Originally, I just had the .1uf on the output going straight to a 100k pot without the 330k. Added the 330k and the other two tone options but don't like the others much. Yep, one has way too much bass and the other is two brittle. I think I will add the pregain control to tame it down. Gonna try some other tone controls, as well. I really love this one...

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Post by RnFR »

you know, I never got around to building this, so I was just looking at the schematic again. I had totally forgotten what it looked like. it turns out, over two years after my initial post, I designed something very similar. not exactly the same, but the basic building blocks have a lot in common. I did a write up explaining the theory behind the design and how it came about.
http://apocalypseaudio.blogspot.com/201 ... drive.html
there's some links to clips in the thread here-
https://www.freestompboxes.org/viewtopic ... ga#p143411

i guess it does happen. weird!
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Post by electrosonic »

I just happened to have my pedal open to replace a broken footswitch when I saw this thread - a little off topic I know.

A common complaint about the original pedal is that the voltage divider at the input to the wah section causes an audible volume drop when the wah is engaged. I have heard people recommend moving the input to the wah to the other side of the 47k input resistor, but this drops the input resistance from 80k (47k+33k) to 33k. What is a better solution? And more generally, why to wahs seem to have such low input resistances?

Andrew.

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Post by glops »

RnFR wrote:you know, I never got around to building this, so I was just looking at the schematic again. I had totally forgotten what it looked like. it turns out, over two years after my initial post, I designed something very similar. not exactly the same, but the basic building blocks have a lot in common. I did a write up explaining the theory behind the design and how it came about.
http://apocalypseaudio.blogspot.com/201 ... drive.html
there's some links to clips in the thread here-
https://www.freestompboxes.org/viewtopic ... ga#p143411

i guess it does happen. weird!
Man, I wonder how those two compare to one another. May have to try your Naga. I added a bmpesque tone control to the end and it sounds quite good. I think I will try a gain control at the input to try to tame it a bit. I

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