Ludwig Phase II Clone Debugging and Miscellany

[petey twofinger]

i thought i posted this yesterday so sorry if this is doubled somewhere else but ...

http://chicago.craigslist.org/chc/msg/3004630602.html

maybe i should put my omnibot up , for 1200 .

[pinkjimiphoton]

tell him we cloned 'em and they won't be worth SH*T

[digi2t]

has anyone else got it up and running yet?

i haven't even begun to populate mine yet...

Working on it. Boards are done. Box is drilled. Wiring, and pedal gutting left to go. Working on it. Missing some hardware though (LED bezels, and 2 footswitches  ), but on their way. I figure, maybe 2 more weeks, maybe 3, before it's running.

Don't worry... you'll ALL know when it is. 

[petey twofinger]

ha !

[digi2t]

Alright, I've got everything wired, and I'm off to to a bad start. I'm not getting my 35v at Q6 emitter. I'm only getting around 18.5v. I'm getting 47.9v from the power supply, and the 36v zener is giving me 35.8v.

Further down the line, I'm only getting about 6v at pad W17. I should be seeing 35v here.

Any quick ideas?

Back to the bench....

[digi2t]

Alright, I've got everything wired, and I'm off to to a bad start. I'm not getting my 35v at Q6 emitter. I'm only getting around 18.5v. I'm getting 47.9v from the power supply, and the 36v zener is giving me 35.8v.

Further down the line, I'm only getting about 6v at pad W17. I should be seeing 35v here.

Any quick ideas?

Back to the bench....

OK... embarassing moment here...

The BD679 was backwards. I guess it just isn't clear enough for me on the board which side the transistor has to go on. Since I'm using a heatsink, I mounted it on the trace side to put the metal side down, with the heatsink underneath it.

R.G., could you please label the Q6 pins on the layout? Save another dufuss like me some troubleshooting time. Thank God I can read a schematic.

I'm off to tune it now... YIIIPPPPPPIIIIIEEEEE!!!!!!!

[R.G.]

Good catch. Yes, it was laid out for top of the PCB. I've updated the project file and will post it as soon as I get a chance.

I put markings on B and E on two different pages and did some warning texts about this three places.

[digi2t]

YYYYYYEEEEEEEEEAAAAAAAAHHHHHHHHHH!!!!!!!!!!

It works... and it's perfect. I used my tuning guide as a rough pathway. I've come to the realization that every unit will probably give different voltage readings, but the fact remains that setting up the initial voltage with R20, and then balancing the Toe up/Heel down COUNTER voltages, is key. This is the biggest PITA, since it involves finding the right engagement point between the rack and the gear, and lots of adjusting between the final angle of the pedal pot, and R31. Once that is done R29 goes to 3.8v on the wiper, and you can adjust R55 and R77 by ear, or by scope. Once you've got the three modes nice and vocally, a final tweak on R29 to finalize the pitch of the YOY. I was lazy tonight, so I went by ear, didn't feel like setting up the scope. Besides, not everyone has a scope, so I wanted to test what was already written here. R65 goes somewhere between 0 and 22K ohms, again, by ear is fine. The remaining two trimmers get cranked until you don't get any whistles or chirps for the filters. They do play a very tiny bit of a role in the sound of the vowel, so if you're anal about it, yes, you can sit there for hours, and nudge them around until you find your Nirvana.

It's just as vocal as the original. Hell... it's so close to the original, it's scary! I'm proud as punch to have contributed to this project, we have a winner. I'm getting all the same vowel sounds that I get with my original unit, whether it's with the animation, or with the pedal alone. I'll get gutshots, and a video done soon. Hopefully by the weekend.

Hot damn!!

[pinkjimiphoton]

LOUD APPLAUSE ERUPTS IN CONNECTICUT!!!!!!!

[R.G.]

Yeeee-hah!!

[Keppy]

Congrats!

[pinkjimiphoton]

we need baby pics and clips!!!

[digi2t]

we need baby pics and clips!!!

I need a 26.3 hour day! 

Coming soon bro. I might be able to post something on Saturday.

Stay tuned.

[pinkjimiphoton]

all good my brother, all good...

it's getting close to me to order parts...i have to save up a while to be able to make it worthwhile, and i figure the more gets built by guys with some knowledge,
the better chance a hack newb like me will be able to pull it off.

can't wait to see it...you and keppy are the first proud papa's!!

[wavley]

My anniversary is in two week, I've asked that a mouser order be my present!

[digi2t]

OK, two bugs.

1) The Fast/Slow switch should be the other way around. On mine, switch down/LED off is fast, and switch up/LED on is slow. Personally, I'd prefer it the other way around. OK... not really a bug, but a lifestyle choice  .

2) It should be corrected on the parts list that the jacks required should be; 2 mono for the outputs, and 2 mono switched for the inputs. The switched jacks should go to ground when not in use. Otherwise, you'll get all kinds of noise from the unused input. This reflects the original units.

Started a new topic with the clone in action. Didn't want to post all that here. http://www.diystompboxes.com/smfforum/index.php?topic=97991.0

Cheers,
Dino

[digi2t]

Oh yeah, we should also mention that the trimmers on the console board should be mounted on the trace side. Makes tuning much easier, not having to have the board out of the box.

[digi2t]

Correction needs to be made to the schematic in the PDF. The Fast/Slow switch poles are labeled backwards, as well as the labelling on the layout. Fast is down, and slow is up.

R.G., is it possible to re-route the two traces (top and bottom poles), to have Fast up and Slow down? The LED can stay as is.

Cheers,
Dino

[R.G.]

Correction needs to be made to the schematic in the PDF. The Fast/Slow switch poles are labeled backwards, as well as the labelling on the layout. Fast is down, and slow is up.

R.G., is it possible to re-route the two traces (top and bottom poles), to have Fast up and Slow down? The LED can stay as is.

Yes, I think it is possible. The only thing preventing a "Sure, no problem" is that I remember that area as being very tight.

I'm pretty sure all the other mods are trivial. And it is a huge help to have you listing things that you ran into for any future changes.

There is one thing. People who've read "PCB Layout for Musical Effects" will remember laboring through the stuff on rules and where you're trying to go. One of the things I did on this layout was try to preserve trace width and spacing so it was feasible for someone with a couple of toner transfers under their belt to do it. So I deliberately pushed everything I could to one copper surface instead of evening it out top and bottom and requiring plated through holes. Double sided copper makes some things easier, like mounting pots and Q6 on one side of the PCB and everything else on the other side. The pins for those parts just solder on the normally component side and solder through. This is harder to do with a single sided PCB.

So - the real question lurking in here is does any further update to the layout give up on aiming at single-sided toner transfer? I'm good either way, because at most I'll only ever build the one set I have, so it's really a question about whether those who come later will nearly always want plated-through holes.

[digi2t]

That's fair enough R.G.

So far, these are "esoteric" adjustments. I mean the unit works as advertised, which is of primary importance, so I'm not really sweating this small stuff. I'm already getting used to the quirks, so it's no biggie for me. If there is a simple fix, then go for it.

Or, we leave it as is. That should cover the "quirky mojo" aspect for the clone  .

Speaking of which (I forgot to mention this before), when I put my Fuzz Rpt./FFM switch to "Both", both colors of my bi-color LED are on. Tracing the circuit, I can understand why, but I might suggest that the builder be judicious in choosing the bi-colour LED here. Mine doesn't give much of a visual difference between the red/green together, and the red alone. It's very subtle, more orange than amber.

*EDIT*-

Here is my "quick and dirty" setup guide for adjusting the trimmers and pedal pot in the clone.

First, some ground rules;
1) I used a Crybaby shell for the pedal, along with a P.E.C. 10K pot. The pot fits well, and is pretty well bulletproof. There are rubber bumpers on the treadle, which cushion the impact between toe and heel down positions. I trimmed these to about 2mm with a razor, to maximize the sweep, yet retaining some impact cushion.
2) I used a BD679 power transistor. All the information below relies on having 48vdc +/-0.1 power supply voltage, and 35.6vdc +/-0.1 at the emitter of the BD679. If your voltages are further from these numbers (within reason), then your pedal will probably not sound quite like mine. This is normal, and nothing that some fine tuning thereafter can't adjust. Like I said, this is to get you close to where you should be.
3) I used 1% metal film resistors, and metal film caps. One exception is the 220pF cap, which is silver mica. I'm not quite sure if that makes much of a difference, but I thought I would throw that out there for good measure.

Now the setup;
1) Install your pot in your pedal. One pole goes to ground, the wiper should be on this side of the pot when in toe down position. Adjust the pot position so as the pot sweep is completely at the end of it's travel when the treadle is completely heel down. In other word, bottom the pedal, bottoms the pot. If you wish, you may also trim the rubber toe/heel bumpers, if you're using a Dunlop type shell, to maximize the amount of sweep. If you do, you can take them down to about 1/8" (3mm), which is enough to cushion the impact. In any case, assure to leave a bit of play on the pot rotation in heel down, to accomodate the deflection of the rubber bumpers. This will avoid having the rack gear jump a tooth if you push heel down too hard.

2) Once the boards are installed and completely and wired, test your power supply, and power transistor voltages. If you're good to go here, proceed to the next step.

3) WITH THE POWER OFF - Adjust the trimmer resistances to the following numbers as illustrated below. If a trimmer seems to drift on the meter, just sit tight until it stops moving, and then adjust. Two lines point to where you should probe the trimmer, with the desired resistance. Since R55 and R77 are in a voltage divider mode, probe one side of the trimmer, then the other. Note as well that R31 will vary with pedal position, so I've given the resistances in toe, and heel down positions.





4) Fire up your unit. One thing that both the clone and the original have in common is the RF29 voltage. Both seem to like 3.80vdc on the wiper to ground. This gives the best vocal quality from all modes. If you're within 0.5vdc of this number, you should be in the park. Just tweaking the trimmer a bit will give noticeable results, so keep track of your adjustments.

5) RF55 and RF77 adjust the F1 and F2 frequencies. You can play with these, again, keep track of you adjustments. You'll see that adjusting one or the other will shift the frequencies, thus changing the vocal qualities of the unit. Keep track of what you're doing, and adjust these to taste if the initial settings don't meet with your satisfaction. A word of warning though, going to far one way or the other, with either trimmer, will send the unit into bad oscillation, give you bad thumping when switching, or thumping when sweeping the pedal. So, go easy!

That's it. That's how mine is set up. If you can get close to the numbers above, you should be able to avoid any bad oscillations or thumps, and get some decent vocal action going.