Ludwig Phase II Clone Tech Notes

[pinkjimiphoton]

good idea...think i may wait tho and do it to the clone, now that the caffiene is starting to settle a little bit, lol...

[pinkjimiphoton]

guys, found this at www.fairradio.com

35vct 1amp 2.5x 2.8x 3 #1341155-2 "rusty condition" for 4 bux apiece...

don't know if this would be right, but it seems to be in the ballpark for size, etc..

[digi2t]

Since these are the tech notes, I decided to post this here.

Jimi sent me the trimmer resistances from his unit on the other thread, and I've been playing with the unit a bit tonight. I realized that trimmer R41 adjusts the frequency range when the unit is in Parallel mode. You can make the sweep brighter or darker, depending on where you set the trimmer. It does nothing in other modes, so far.

Since I've recorded all my trimmer settings, I'll go through my unit again, and record what trimmer affects what. I already know what some do, but others (like R41) only respond when the unit is in a certain mode. When I've got them figured out, I'll post them.

Cheers,
Dino

[R.G.]

Since these are the tech notes, I decided to post this here.

Jimi sent me the trimmer resistances from his unit on the other thread, and I've been playing with the unit a bit tonight. I realized that trimmer R41 adjusts the frequency range when the unit is in Parallel mode. You can make the sweep brighter or darker, depending on where you set the trimmer. It does nothing in other modes, so far.

Very good to know!

Since I've recorded all my trimmer settings, I'll go through my unit again, and record what trimmer affects what. I already know what some do, but others (like R41) only respond when the unit is in a certain mode. When I've got them figured out, I'll post them.

That would be very useful. I haven't yet done enough analysis to figure out specifically what dinks with what. A guide to that would be very nice indeed. I was waiting for the first boards to be tried to dive into that. I *think* the voltage/net labeled 'gamma' (?) sets some kind of basic operating voltage/frequency for both filters, and then each one has an independent amount of that, controlled by R41 and R62. The two 50K trimmers balance the two sides of each formant filter by letting a different amount of the control voltage from the modulation voltage go through. It's not clear to me what happens then.

I *think* they work by varying the transconductance of the transistors in the filter, in a similar concept but different manner than the Moog ladder filter. I haven't been able to map that to a common filter format yet. I just went state variable for the thing I did.

[Keppy]

I haven't been able to map that to a common filter format yet. I just went state variable for the thing I did.

Sounds like between your project, the Phase II, and the Vocalizer, we're starting a vocal wah trend. Should be fun!

[pinkjimiphoton]

testing....the forum was down earlier!!

weird!

ya know, thinking about it, i guess it does make sense to make a standard wah option available...the counter position is pretty close already.

so keppy, any chance on a BOM? i'm really curious which transistors you ended up choosing for the project...

i know i'm impatient, lol...sorry... after all this time, i wanna see this thing live again, and hopefully even be improved upon!!


anyways....look forward to more updates when they're possible...thanks to everyone involved in this!

[Keppy]

so keppy, any chance on a BOM? i'm really curious which transistors you ended up choosing for the project...

R.G. made the BOM, but he's waiting for me to test the circuit before putting it out there I think. The transistors are the ones he mentioned earlier in the thread (or maybe the other one): 2N5551 NPN & 2N4401 PNP, with a TIP112 Darlington for the regulator (Q6 on the console board). That's off the top of my head, so sorry for any mistakes.

As you can see in the photo I posted a few days ago, I socketed all of them in case any need to be switched to something else. I had been thinking about trying R.G.'s suggestions first, then replacing all of them with 2N3904/3906 just for comparison's sake, but they were such a pain to jam in the sockets that I'll probably just leave it as is unless it doesn't work.

[digi2t]

Hi guys,

I should have the info on the trimmers in the next few days. There are still 3 trimmers that have me perplexed, but it's probably because I haven't figured out the right configuration yet to really hear what's going on.

I have found that some are interdependant, which is normal, to achieve the right formant zones (vowels). There is even one (sorry, I don't have unit in front of me right now, so, no number) that seem to change the wave. For lack of more precise terms, it seems to adjust from a sine, to more of a square wave. It gives the yoyoyoyoyo somewhat better definition i.e. yo yo yo yo yo. Then, there are 2 trimmer that are VERY interactive in B mode, to the point that I could hear "whatsup/whatsup/whatsup" coming out of the unit. THAT really blew my mind. In B mode you can somewhat vary the alternance of certain vowels i.e. "aoaoaoao" or "aiaiaiaiai" etc. Also, setting up the treadle pot sweep is important as well, since you can end up with a "deadzone" (no audible change) at either end of the remaining pot travel. I am sooooo glad that I have everything documented, or else one could seriously mess up the sound of this puppy.

I figure by Sunday, I'll be posting the results. So far, it's quite incredible how totally engrossing playing with these trimmers can be. A day can just fly by, and you feel you're barely scratching the surface.

[pinkjimiphoton]

i'm really thinking the trimmers should be moved externally for fine tuning...maybe put a switch to select between the internal trimmers and external pots so we can move things around. the trimmers really do do some insane stuff, and are highly interactive in some cases.

like dino said, man, you could play with this thing for days and find all kindsa weird stuff.

i'm not surprised you got it talking...that's the pedal i remember in days of yore.

[digi2t]

maybe put a switch to select between the internal trimmers and external pots so we can move things around.

I think that would really make an already complicated unit a bit too.... over the top. Considering that you have a choice of single vowels, counter vowels, or parallel vowels, I think really give one enough meat to work with. Besides, the major changes that you can incur with just minor adjustments, would make external trimmers a nightmare to start fiddling with.

The reason for which I'm investigating the trimmers, is so we can a least have some sort of tuning guide to refer to. Since tuning info is non-existant (no news from the Ludwig guy yet), I figure that we should have at the very least an idea on what to look for when it comes time to set this sucker up. Also, if we can figure out A+B=C, then we'll also know what to look for if we can't achieve C. Or, if one wishes to set the unit to sound a certain way, then we can recommend which trimmer(s) to play with.

I just think that it important to get the most amount of info to Keppy in regards to this, at this point. Since he's so close to getting the prototype powered up, it would be nice that he at least has some info from an original units setup to reference to.

[pinkjimiphoton]

dig it. good thinking dino!

on mine, when i first opened it, ALL the trimmers were at the half way mark except for the horizontal one, which was almost all the way up, for what it's worth.

the setting is sent you were a result of playing with it and trying to tweak it in for the best sounds by ear...so it'll be interesting to see what's what, as i'm sure we've both got parts that have drifted quite a bit from spec in various parts of the circuit.

[Keppy]

I just think that it important to get the most amount of info to Keppy in regards to this, at this point. Since he's so close to getting the prototype powered up, it would be nice that he at least has some info from an original units setup to reference to.

Thanks, I appreciate it!

Incidentally, while we're on the subject of trimmers, there's one that is listed in the schem as 150R. As that seems to be a non-standard value these days, I used a 100R, since that's the trimmer Jimi replaced and that's the value he used and it worked for him. I did this despite the fact that it makes more logical sense to use a 200R replacement as all the resistance values of the original trimmer would then be available. Dino, could you report back to us on whether it's worth using a 200R trimmer to get resistance values in the 100-150R range?

[pinkjimiphoton]

the 100r seemed to be fine, the "sweet spot" is right about 80-90r keppy. 200 will be fine, but you'll probably find most of it above 100r is unusable. if memory serves, it will make the unit self-oscillate if too high.

hope that helps bro! that populated board is a thing of beauty!! that's the control board and the fall board on one pcb, right?


sweet, dude, very sweet!!

[Keppy]

that's the control board and the fall board on one pcb, right?

Yup, I left them together. R.G. intended for them to be split apart, but I couldn't see any advantages to that in the enclosure I got (1590D). If all goes well, the enclosure will open up book-style, folding the board on nicely trimmed wires. If anything goes poorly, it will be a tangled mess that I will never want to open again for fear of breaking some part of the squished-together wiring.  

[digi2t]

Yup, mine's a 150R, and also confirms the setting in Jimi's unit. Mine is set about the middle of the range, which is close to Jimi's readings. I think it would be best to use a 200R, since this trimmer is responsible for vowel frequency, so a little more is better. 100R might cut it a little close if we take related component tolerences (resistors, capacitors) into consideration.

but you'll probably find most of it above 100r is unusable. if memory serves, it will make the unit self-oscillate if too high.

Correct me if I'm wrong, but the 150R is trimmer R29, but I find that trimmer R65 (25K) will set it into oscillation if set too high. I find that anything over halfway on R65 will induce oscillation, especially with the treadle in the heel down position.

Keppy, does your board allow for the use of multi-turn Bournes trimmers? I'm a big fan of them, and would like to use them for my clone. Say, these ones;
http://www.bourns.com/data/global/pdfs/3266.pdf

They have the "Y" pin configuration, so, would they fit on your board?

[pinkjimiphoton]

yah, a few of them will send it into self oscillation...

i think it's kinda cool!!

well, maybe not in a musical context, but...

[digi2t]

OK, here is what I've discovered so far insofar as the trimmers are concerned.
On the console board;
R4 - RATE range adjustment (shifts the hi/lo range of the RATE slider).
R20 - COUNTER and VOWEL tone adjustment.

On the motherboard;
R29 - Frequency adjustment for all modes. This (to me) is the "Jesus" trimmer. Without the fuzz on, this, R20, and R31 will primarily be responsible for proper vowel sounds and annunciation.
R31 - Hard to describe this one, but to my ears, it sounds like a wave adjustment, sort of like going from sine to square.
R55 - FUZZ RPT. frequency adjustment (tone of the percussive beat).
R62 - FUZZ RPT. signal frequency adjustment (tone of the fuzz signal in FUZZ RPT. mode).
R65 - FUZZ RPT. gain (gain of the percussive beat). Have to be careful with this one, too much gain bleeds out oscillation everywhere, even bypassed.
R77 - FUZZ frequency adjustment in PARALLEL mode.

That's the best I can describe them in my best layman's terms.

[pinkjimiphoton]

excellent work dino, you seem to have really figured this stuff out bro!! i may play with the trimmers some more, now that i have a clue what some of them actually do!

[digi2t]

I think we should rename this puppy. In FUZZ RPT. mode, it becomes the Ludwig Phase II Bongo Synth. 

[Keppy]

Keppy, does your board allow for the use of multi-turn Bournes trimmers? I'm a big fan of them, and would like to use them for my clone. Say, these ones;
http://www.bourns.com/data/global/pdfs/3266.pdf

They have the "Y" pin configuration, so, would they fit on your board?
[/quote]

Those look similar to the multi-turns I have here. They will physically fit in the available space, but the pin spacing on the version of the fall plate board I have would be awkward for them. I emailed R.G. about it, and he says he has since arranged the pads in a more versatile manner, so those will probably work.