Ludwig Phase II Clone Debugging and Miscellany

[pinkjimiphoton]

yah, they were definitely gobbling the brown acid...

all the controls, i mean ALL of them, are HIGHLY interactive.

once ya follow dino's set up guide, you may wanna just barely tweak the trimmers here and there some to see what happens.

[Keppy]

I'm still kind of amazed that the factory schemos worked as shown.... 

It didn't.

Remember all the inaccurate resistor values and the backwards UJT? And the missing booster? And all the switching that wasn't diagrammed at all? And the missing pot values? I'm sure I'm forgetting something...

[pinkjimiphoton]

I'm still kind of amazed that the factory schemos worked as shown.... 

It didn't.

Remember all the inaccurate resistor values and the backwards UJT? And the missing booster? And all the switching that wasn't diagrammed at all? And the missing pot values? I'm sure I'm forgetting something...

amazing drummers got it to work at all.... god loves fools and little children, they say...

[R.G.]

It didn't.

Remember all the inaccurate resistor values and the backwards UJT? And the missing booster? And all the switching that wasn't diagrammed at all? And the missing pot values? I'm sure I'm forgetting something...

Oh, sure. Slap me with the facts about how bad the good old days really were...

[Govmnt_Lacky]

http://www.diystompboxes.com/smfforum/index.php?topic=36392.msg917803#msg917803

 

[R.G.]

Wow! Nice work!

[Keppy]

+1. I dig the smaller knobs for the last two controls.

[wavley]

Has anybody tried using a JFET for the Hi-Z input buffer?  I just bought a new amp and after playing straight into it and then plugging into my rig I noticed that I'm loosing some low end and a little sparkle leaving just the haunting mid range plugging into the Lo-Z input gives my low end back (but it distorts too easily), so I was going to up the input cap (QF3, if I remember correctly from glancing at the schem last night).  So I figured that maybe I could tinker with this buffer a little while I'm in there.

There's 35V running around in there, so it rules out my MPF102's, but I do believe I have a small stash of J201's.

[R.G.]

The Hi-Z input could certainly profit from some upgrading.

... but then it wouldn't be *original*   

The input there is about 200K if I did the math right, and with a 0.01, that gives a rolloff of 79Hz, so you are losing some bass, and probably some treble from the loading on guitar pickups.

One easy upgrade would be to sub in a 2N7000 or BS170 MOSFET for the NPN, and change the biasing 680K's up to about 2.2M each. That thing's running from the 17V supply, so it probably has enough voltage that you don't have to diddle the values of the bias network to make up for the 2-4V of the MOSFET gate threshold that the output resistor will drop.

[Govmnt_Lacky]

Personally... and while we are talking about Phase 2 modding....

I wouldnt mind smoothing out the Fuzz on this bad boy. To me, it just seems too sputtery and grainy and the decay has something left to be desired.  I know it isnt the MAIN focus of the pedal but.....

Thoughts?

[wavley]

The Hi-Z input could certainly profit from some upgrading.

... but then it wouldn't be *original*   

The input there is about 200K if I did the math right, and with a 0.01, that gives a rolloff of 79Hz, so you are losing some bass, and probably some treble from the loading on guitar pickups.

One easy upgrade would be to sub in a 2N7000 or BS170 MOSFET for the NPN, and change the biasing 680K's up to about 2.2M each. That thing's running from the 17V supply, so it probably has enough voltage that you don't have to diddle the values of the bias network to make up for the 2-4V of the MOSFET gate threshold that the output resistor will drop.

Mine is built in a Jonathan Livingston Seagull lunchbox, at this point I'm not sure original is a concern for me   My Traynor was a bit boomier than the Cornford I just acquired so it didn't come up as an issue until last night, I foresee it being a bigger problem when I play my baritone.

I *think* I might have a BS170 around, I know I have an IRF510 I picked up at Radio Shack because I saw somebody had built an SHO with one that I never got around to building.

I REALLY need to make a parts order soon to replenish my stock and build that Schumann who's board is sitting on my nightstand.

[wavley]

So I bypassed the .01 cap with a 10uF and all my bass was back.  I didn't get around to putting in a MOSFET yet, hopefully I'll get to that soon.

I think I've mentioned this before, but has anyone else noticed that the effected signal is louder than the bypassed?  Or is there something wrong with mine?  It certainly doesn't sound broken or anything but often I find myself reaching for a volume knob and then turning back up after I turn it off.  I guess my question is, should I be looking for an issue, or should I just add an attenuator to the effected output?

[wavley]

Well, I finally got around to adding a volume control to my effected out and combined with the mixing resistors I added a while back so I could use the stereo out switch as a mono clean blend I have to say that it's made this so much more of a versatile unit!  Now I can push it to the background and have it follow cleaner sounds for added dimension so I'll be able to turn it on a little more often without melting people's faces and brains.

[newperson]

have a schematic drawing of the volume mix add?

[wavley]

have a schematic drawing of the volume mix add?

It was a while back that I added the mixer resistor, but it was probably a 10k jumped from the stereo out jack to the normal out.  The effected volume control is just a 500k pot (it's what I had handy) wired as a voltage divider interrupting the wire from the wet out to the bypass switch.

A better way to do it might be to add a pot with the center lug going to the wet out lug on the bypass switch with the stereo (dry) out wire and the wet wire on the outside lugs to use as a blend control.  I wanted to keep the stereo out just in case, I can add a switch to kill the dry signal going to the main out and have the original functionality.

[wavley]

The Hi-Z input could certainly profit from some upgrading.

... but then it wouldn't be *original*   

The input there is about 200K if I did the math right, and with a 0.01, that gives a rolloff of 79Hz, so you are losing some bass, and probably some treble from the loading on guitar pickups.

One easy upgrade would be to sub in a 2N7000 or BS170 MOSFET for the NPN, and change the biasing 680K's up to about 2.2M each. That thing's running from the 17V supply, so it probably has enough voltage that you don't have to diddle the values of the bias network to make up for the 2-4V of the MOSFET gate threshold that the output resistor will drop.

Turns out I have some VN10 and VN99 MOSFETs around, but I was recently working on a friend's Marshall and it's input VN2410 MOSFET was cooked, of course I don't know anything about what they were doing to the amp when it happened, but it makes me want to overbuild on the reliable side.

Thoughts from the head of R.G. on this one?

[R.G.]

Paralleling RF7 and RF8 with 1N4007 diodes pointing up would help. Also, put a 12V zener with anode on the gate after the 1K and cathode to the source. This won't help if someone connects AC wall socket voltage to it, but it willl probably keep all minor disasters at bay.

[Govmnt_Lacky]

Question for RG or others that have built this pedal.... I know I have asked this before and I cannot find my notes on the matter so....

Specifically, I am addressing Page 8 of the Geofx 2nd run build document.

According to what I see... it is OK to have the FWB rectifier installed AND use a 48VDC wall wart. Is this correct? Or, does the FWB need to be removed and jumpered when using the wall wart?

Also, according to the wiring diagram on Page 8, it says that when using the DC wall wart, power wire AC/+DC2 is not used BUT... in the picture, that is the wire that they show connected and labeled as AC/+DC1 

Is this a typo on the doc? Can either of the power inputs to the PCB (+DC1 or +DC2) be used?

Thanks!   

[R.G.]

According to what I see... it is OK to have the FWB rectifier installed AND use a 48VDC wall wart. Is this correct? Or, does the FWB need to be removed and jumpered when using the wall wart?

Also, according to the wiring diagram on Page 8, it says that when using the DC wall wart, power wire AC/+DC2 is not used BUT... in the picture, that is the wire that they show connected and labeled as AC/+DC1 

Is this a typo on the doc? Can either of the power inputs to the PCB (+DC1 or +DC2) be used?

Typo?? I'm sure there are typos in there. It's just FINDING them that's the problem!   

The full wave bridge has four diodes in it. Two of them are identical to the two diodes that were in the original, and make the positive side of the power supply. The two "bottom side" or negative diodes are optional in this circuit. They can be connected to circuit ground by the jumper. The two AC/+DC pads are identical, and interchangeable. They don't care - which is probably why I made that confusing. I really promise it wasn't deliberate... 

If you use a DC wall wart, connect the (-) to the circuit common pad, and the (+) to either one of the AC/DC pads. Doesn't matter which one. You can put in the FWB, which offers polarity protection, put in one diode for polarity protection, or just jumper in the FWB position, which is complicated. I'd advise you to put in the FWB. Do not use the jumper in this case.

It is also possible, but less desirable IMHO, to put in the FWB, put in the jumper, and connect your DC wall wart across the two different AC/DC pads, and connect nothing to the power common pad. This lets the FWB sort out the polarity and connect the right polarity of incoming DC power to the V+ and Common. FWBs work with DC too. But the incoming DC wall wart (-) now is one diode drop BELOW signal ground, which can lead to some interesting circuit malfunctions when used with other equipment if the wall wart (-) goes other places too.

So if you have a DC wall wart, use the FWB, do NOT use the jumper, and connect the wall wart (-) to power common, wall wart (+) to either AC/DC pad and ignore the other one.

And by now you are beginning to understand how I made the instructions confusing. 

[Govmnt_Lacky]

So if you have a DC wall wart, use the FWB, do NOT use the jumper, and connect the wall wart (-) to power common, wall wart (+) to either AC/DC pad and ignore the other one.

I ended up connecting the DC jack exactly like your picture on Page 8 of the document (making the DC jack center POSITIVE of course to match the wall wart) and I did install the FWB so... it looks like all is good  

Thanks again RG!

Now, I need to get my CV pot fitted with the gear (ugh) and get that built up and then I can adjust trimmers and fire it up! (and then trim some more  )