Ludwig Phase II Clone Debugging and Miscellany

[digi2t]

OK, I figured that if I could vero an Infinitphase, I might just take a shot at a vero of the Ludwig. I don't plan on having anymore boards made, but I would like there to be another option for DIY'er as craz... er... dedicated as myself (OK, crazy too  ).

R.G., could you please explain the numbering convention you used for the wire pads on the boards? I tried following it vis-a-vis the schematic, but some of the numbers don't make sense to me, i.e. pad number on schematic not corresponding with counting pads/where wire is going in wiring diagram.

Am I not seeing something here?

[pinkjimiphoton]

you are a madman. that's why we love ya, bro!! 

[Keppy]

A synth player wants me to build him one of these, so I've been investigating using the PII with line-level devices. The lo-Z input seems to work okay, and there's enough gain in it that I get a reasonable output level, especially with the filters on (and why would they be off? ). There's some distortion with the fuzz off, but there's some of that using a guitar anyway. Anyone out there got a PII and a line-level synth to play through it? I'd appreciate another opinion. So far I'm planning to build it stock but increase the Lo-Z Balance pot and use Dino's trimpot mod for the input level to the filters.

[digi2t]

A synth player wants me to build him one of these, so I've been investigating using the PII with line-level devices. The lo-Z input seems to work okay, and there's enough gain in it that I get a reasonable output level, especially with the filters on (and why would they be off? ). There's some distortion with the fuzz off, but there's some of that using a guitar anyway. Anyone out there got a PII and a line-level synth to play through it? I'd appreciate another opinion. So far I'm planning to build it stock but increase the Lo-Z Balance pot and use Dino's trimpot mod for the input level to the filters.

Try swapping out RF26 for a 50K trimmer first, and dialing down the signal hitting the filters without fuzz. You'll find that you'll also be able to balance between the fuzz and clean volume levels as well. Let us know how incresing the balance pot works out.

For those wondering, yes, I have started a PII vero. This is what I have to date;



I'm using 1W carbon film resistors to power the LED's, to cut down on the parts count. The blank section in the middle is where the input buffers, fuzz section and output amp will go. I'm working on that today. Amazingly enough, this vero seems to be a bit easier to put together than the Infinitphase, but I'm sure I'm fooling myself. I've probably bodged the filter sections, and I'll have some hefty corrections to do.

At 6.5" x 4.5", this board will easily fit the Multicomp box that I used for my Ludwig. Once all the components are aboard, I might be able to shrink it a tad more, but I don't see it making it into a 1590DD.

[Keppy]

I was already going to put that trimmer in. I mostly want to check that others are able to get output volume reasonably close to input volume with a variety of line-level devices, since I don't have many to test with (just a theremin and cheap digital piano).

[R.G.]

R.G., could you please explain the numbering convention you used for the wire pads on the boards? I tried following it vis-a-vis the schematic, but some of the numbers don't make sense to me, i.e. pad number on schematic not corresponding with counting pads/where wire is going in wiring diagram.

Am I not seeing something here?

Sorry - been traveling, and just got back to this.

Actually, no, there isn't something you're not seeing here. The wire pad numbering convention is arbitrary. It was done automatically (which means "without making sense to a human") by the schemo program. Well, it's probably not truly random. I think the program numbers them from left to right across the page in rows from the schematic placement, or tries to. That's probably what accounts for some of them seeming to make sense, the others not, as the layout may tend to follow the schematic graphic arrangement in some place, not others.

As long as wire-pad-to-wire-pad is preserved, it's fine to renumber them to anything. In fact, for a rework into vero, it probably makes sense to put them where you need them for the vero to make logical sense, then renumber or rename them to match the physical layout.  I didn't do that last step on the PCB. I probably will if there's ever another commercial run.

[UKToecutter]

Interesting .......
I was thinking of laying out a pair of boards with male and female headers to mate between the two and holes in the bottom board to allow access to the trim pots....

Andy

[R.G.]

It's not a big problem. That would take me an hour or so, tops.

However, that makes the layout highly dependent on the availability of the headers and sockets chosen.

[wavley]

Interesting .......
I was thinking of laying out a pair of boards with male and female headers to mate between the two and holes in the bottom board to allow access to the trim pots....

Andy

It's not a big problem. That would take me an hour or so, tops.

However, that makes the layout highly dependent on the availability of the headers and sockets chosen.

I have to say that would be awesome!  The offboard wiring got tedious on this one and that's with board mounted pots and switches! I would build a second one if I didn't have to do all that wiring again!

[Govmnt_Lacky]

The offboard wiring got tedious on this one and that's with board mounted pots and switches! I would build a second one if I didn't have to do all that wiring again!

Doing all of the wiring is not that big of a deal to me. Keeping all of it neat and tidy IS A HUGE deal for me 

[digi2t]

Well this is what I came up with. Still needs trace verfication for the buffer/amplifier section. Sorry, I couldn't get it to 1590DD size  .



I've used the same component numbering convention, so as to keep some uniformity with the build document. For the LED resistors, I used 8.2K 1 watt carbon comp dimensions.

I'm going to do a full verification trace next, I'll let you know when it gets my official okee dokee.

No worries on the wire pad numbers R.G.. I traced it out the offboard wiring on the schematic, it's fine.

[wavley]

The offboard wiring got tedious on this one and that's with board mounted pots and switches! I would build a second one if I didn't have to do all that wiring again!

Doing all of the wiring is not that big of a deal to me. Keeping all of it neat and tidy IS A HUGE deal for me 

OK, you got me, neat and tidy is my deal too.

[Vince_b]

I have just noticed that my Ludwig (clone) make my sound distort when it's bypassed. With active pickups it's even worse, it sounds like I'm playing through an overdrive. Has anyone  experimented something similar?

[R.G.]

I believe this is caused by the fact that the input to the Ludwig never really "bypasses". It is always there, kind of sloppily "buffering" the signal.  If you feed it too big a signal, it will distort, and I'm guessing that this is what's happening to you, especially if it's worse with active pickups. There is some possibility of a bug in your input stage, and it's worth trying to run that down.

There are many different minor issues with the Ludwig P2 from a design standpoint, and this is one of them.

See if you can measure the dc voltages on the first four transistors at the input and post them here. We may be able to find a bug if there is one. But you may have to do some other kind of bypass to get around this.

[Keppy]

If you have active pickups, you can try using the Lo Z input and see if it helps.

[Vince_b]

I think I have found the "problem". It happens that I was plugged into the Lo Z input. I switched to the Hi Z input and now there is no saturation. That explains why I haven't noticed this before.
My guitar with active pickups still distort in both input, but when I think about it, these pickups can saturate most clean amps just by themselves  .

I will still post the voltages of the first four transistors to make sure that everything is alright because I'm a little bit surprised that the Lo Z is more prone to get overdriven than the Hi Z.

Q1
E: 35 v
B: 32 v
C: 36 v

Q2
E: 0 v
B1: 0.44 v
B2: 15.6 v

Q3
E: 0 v
B: 0.67 v
C:0.06 v

Q4
E: 0 v
B: 0.06v
C: 14 v

[digi2t]

I think I have found the "problem". It happens that I was plugged into the Lo Z input. I switched to the Hi Z input and now there is no saturation. That explains why I haven't noticed this before.
My guitar with active pickups still distort in both input, but when I think about it, these pickups can saturate most clean amps just by themselves  .

I will still post the voltages of the first four transistors to make sure that everything is alright because I'm a little bit surprised that the Lo Z is more prone to get overdriven than the Hi Z.

Q1
E: 35 v
B: 32 v
C: 36 v

Q2
E: 0 v
B1: 0.44 v
B2: 15.6 v

Q3
E: 0 v
B: 0.67 v
C:0.06 v

Q4
E: 0 v
B: 0.06v
C: 14 v

Yo Vinny, just out of curiousity, what transistors did you use for QF 1 - 4? (I believe you meant QF, and not Q for the transistors you measured?)

I don't use actives, but I do use some pretty hot passives (18K to 22K range), and I found that 2N5088 worked much better for me in these slots. From my research, I found that they are a better match to the original transistor spec's, giving voltages very close to the original units as well.

[R.G.]

I'm not surprised that the overload characteristics of each input are different, though. The input to the high-Z is an emitter follower, and has a biggish input range while the Lo-Z is an amplifier with a smaller range.

One simple thing you could do to adapt the Ludwig to your guitars and playing style is to put a signal divider in front of the input just to lower the signal level of your guitar down til it quits overloading the first stage(s).

I actually need to look at the voltages on QF1-QF4. Sorry, I realize I wasn't clear about that.

[Govmnt_Lacky]

VERY GOOD info for me! I am about to embark on completing my Ludwig build and I use Active buckers run at 18V 

@Vince

Did you also use shorting jacks for the Lo Z/Hi Z inputs so that the unused input would be shunted to Ground?

Thanks SO MUCH to Dino, RG, and all who have contributed! Hoping to have some actual build input to this thread this weekend! 

[digi2t]

Did you also use shorting jacks for the Lo Z/Hi Z inputs so that the unused input would be shunted to Ground?

Uh yeah, I forgot to mention that one too, but it's pretty clear in the build doc. Check the wiring section, page 7.