Pigtronix Philosopher's Tone Germanium Gold LTD  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
dellamorte
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Post by dellamorte »

when i breadboarded the compressor section there is no connection from 9v to pin 6 of U1b
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mysticwhiskey
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Post by mysticwhiskey »

I'm breadboarding this and have got almost everything in place except for the resistors. Since I'm colour-blind I'm having trouble deciphering the resistor colour codes, if anyone can help with identifying the colour codes from jwpartain1's pictures in the first page, let me know!

(jwpartain1, where are you... :lol: Hope you can help with the resistor identification! We might need higher-res pictures...)

Here's the latest layout, with component names to match the latest schematic:
PCB Trace With Component Names V0.6 20110207.png

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jwpartain1
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Post by jwpartain1 »

Hey, sorry it's been a while. My Philosopher's Tone has been out of my hands for a little while. Hopefully I've got some info that will help.

There is definitely a connection b/w U1 PIN 5 and 9V, not PIN 6. This was stated above.

There are no ground connections on the right side of those diodes on the far side.

The right side of D10 does connect to U3 PIN 7 and lug 3 of the GRIT control.

R1 = 10M

I'm having trouble getting all the other resistor values. It's hard for me to differentiate colors on these tiny things and desoldering is proving to be difficult. I'll try to get some better pics up soon. Again, sorry for the long lapse in any help from me. Thanks for all your super work mysticwhiskey! :applause:

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Post by JakeFuzz »

Pictures are rough. Here is the best I can figure with the lighting situation. Definitely need another pair of eyes going over this. (*) marks the ones I am really not sure about :hmmm:


R9: Brown-Black-Black-Green-Brown
* R5: Yellow-Red-Black-Brown-Brown
* R12: Blue-Yellow-Black-Red-Brown
R11: Brown-Black-Black-Orange-Brown
R10: White-Red-Black-Brown-Brown
R8: Red-Black-Black-Red-Brown
R6: Black-Red-Black-Black-Brown
R3: Yellow-Blue-Black-Brown-Brown
R4: Red-Blue-Black-Brown-Brown
R13: Red-Red-Black-Yellow-Brown
R14: Red-Red-Black-Brown-Brown
R17: Red-Black-Black-Red-Brown
* R15: Orange-Black-Black-Orange-Brown
R21: Red-Blue-Black-Brown-Brown
R20: Yellow-Blue-Black-Brown-Brown
* R16: Yellow-Purple-Black-Silver-Brown

R7, R2, R22 - I just cannot see or figure out

I dislike these 5 band resistors.

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jwpartain1
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Post by jwpartain1 »

R2 = 10k
R3 = 470k
R4 = 2.7k
R5 = 4.2k (3.9k ?)
R6 = 120 ohm
R7 = 1.8k
R8 = 27k
R9 = 150 ohm
R10 = 9.1k (8.2k ?)
R11 = 100k
R12 = 6.3k (6.8k ?)
R13 = 2.2M
R14 = 12k
R 15 = 100k
R16 = 47 ohm
R17 = 7k
R18 = 10 ohm
R19 = 1.5 M or 15 ohm :slap: I know.. I'm having trouble with gold/yellow. Looks like 1.5M with a MM read.
R20 = 56k
R21 = 2.7 k
R22 = 100k

OK, here's what I've got. If I were breadboarding this, I wouldn''t take these exact values 100% seriously, definitely rough. Definitely.. This is just me looking at the bands and using Electronics Assistant...without a magnifying glass :roll: I'm getting one soon!

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Post by mysticwhiskey »

I've been meaning to finish the circuit on the breadboard and try the resistor values given, but I've been kind of busy building an amp (my first build, a Fender 5E3 - just fired it up for the first time this evening!). Hopefully will have some time in the next week or so. Haven't forgotten about it! :)

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Post by jwpartain1 »

Dude, don't worry about a thing, I'd be neck deep in that amp til I was done! :) Hope you enjoy it.

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Post by mysticwhiskey »

Quick update: I've breadboarded it and it works (sort of)...

* Compression circuit works, but I had to reverse C14, like dellamorte had to do. Without doing this, eventually C14 won't discharge and the vactrol LED lights only a tiny bit.
* Instead of a vactrol I used an LDR+LED pair
* Getting distortion on the wet signal, even with the 'Grit' turned down.
* The Grit pot goes from minimal to all out fizzy broken distortion - a little too much gain there I think. Reduced R19 to 22 ohms and got no gain at all in the grit circuit. Will experiment with values to find a happy medium.
* Tone pot has a very minimal effect on the signal, near imperceptible when rotating the pot from one end to the other.

Time to bring out the oscilloscope I think, to see where the unwanted clipping is happening.

I noticed the latest schematic I posted a while ago is incorrect, I thought I had uploaded the new one. Here it is, the only real difference is the removed 9V connection to U1-6.
PigtronixPhilosophersToneSchematicDraft_0.7_20110208.png

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Post by andersom »

Any news mysticwhiskey?

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Post by mysticwhiskey »

Sorry for the lack of updates. Over the last week or so I've been playing around with the breadboarded circuit a bit more, and it basically works albeit with a slightly distorted signal through the compressor stage. Some observations:

* I used jwpartain1's resistor values (more on this later)

* I suspect the properties of the vactrol are important - things like LDR maximum resistance and responsiveness, and the brightness of the LED. I used a LDR (20M dark resistance, 5K light resistance) and a blue LED together in some black heatshrink (two layers of heatshrink to be sure it's lightproof!). The blue LED seems to work a bit better than a yellow LED I tried. I wonder what the actual vactrol model # is that's used on the real pedal?

* The 2200uF capacitor actually doesn't need to be reversed. The orientation as shown on the schematic is correct - if the cap is reversed then the lower half of the wet signal is completely clipped. Observing the wet signal waveform over time shows the signal eventually gets distorted on the lower swing. When I take out the cap, discharge it and put it back in, after a few seconds (once the cap starts to charge up) the compression seems to be working quite well. But after about a minute it works less well.

* The use of a low-noise quality dual opamp for U1 is likely to be important. I don't have an NE5532 lying around, so I tried both JRC4558D and TL072 opamps. TL072 seemed a little bit better, but still a bit noisy. However this might not be a big deal, since my breadboarded circuit is unshielded and prone to interference. The circuit layout on the breadboard is almost certainly not ideal either which probably doesn't help :).

* I had to bump up the value of R7 to get the tone control to work properly

* I reduced the value of R19 as the gain of the grit section was way too high

* When the sustain pot is set to 50%, the level of the wet signal matches that of the dry signal. Maxing it out means the wet signal is dirty, even with the 'grit' control set to minimum - jwpartain1, does your pedal operate like this?

Will provide another update later with the actual resistors values I'm using. I may have changed so other values, but from memory I didn't end up changing many. I experimented with a whole bunch of different values, and temporarily placed potentiometers instead of resistors to see the effect of different resistances in parts of the circuit.

Attached is the breadboard layout I'm using. Not included is the power supply section.
Philosophers Tone DIYLC Breadboard Layout.png

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fakcior
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Post by fakcior »

Vactrol looks like VTL5Cx - probably VTL5C9.

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Post by jwpartain1 »

Well, with the BLEND at 50%, and SUSTAIN at 50%, I've got a 1:1 ratio. If this isn't what you're asking, where is your blend knob?

As you have said, there shouldn't be any clipping.

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Post by bootle »

askwho69 wrote:Any update on this :D :hmmm:
+1

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Post by yurka723 »

+1

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Post by jstbrowsin »

+2 :scratch:

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Post by jstbrowsin »

[smilie=bump.gif] anyone please? :scratch:

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Post by pietro_moog »

+3
i'd love to see it traced

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Post by seedseed »

any updates on verification of the schematic on this one :hmmm:

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Post by jwpartain1 »

mysticwhiskey wrote:Over the last week or so I've been playing around with the breadboarded circuit a bit more, and it basically works albeit with a slightly distorted signal through the compressor stage. Some observations:

* I used jwpartain1's resistor values (more on this later)

* I suspect the properties of the vactrol are important - things like LDR maximum resistance and responsiveness, and the brightness of the LED. I used a LDR (20M dark resistance, 5K light resistance) and a blue LED together in some black heatshrink (two layers of heatshrink to be sure it's lightproof!). The blue LED seems to work a bit better than a yellow LED I tried. I wonder what the actual vactrol model # is that's used on the real pedal?

* The 2200uF capacitor actually doesn't need to be reversed. The orientation as shown on the schematic is correct - if the cap is reversed then the lower half of the wet signal is completely clipped. Observing the wet signal waveform over time shows the signal eventually gets distorted on the lower swing. When I take out the cap, discharge it and put it back in, after a few seconds (once the cap starts to charge up) the compression seems to be working quite well. But after about a minute it works less well.

* The use of a low-noise quality dual opamp for U1 is likely to be important. I don't have an NE5532 lying around, so I tried both JRC4558D and TL072 opamps. TL072 seemed a little bit better, but still a bit noisy. However this might not be a big deal, since my breadboarded circuit is unshielded and prone to interference. The circuit layout on the breadboard is almost certainly not ideal either which probably doesn't help :).

* I had to bump up the value of R7 to get the tone control to work properly

* I reduced the value of R19 as the gain of the grit section was way too high

* When the sustain pot is set to 50%, the level of the wet signal matches that of the dry signal. Maxing it out means the wet signal is dirty, even with the 'grit' control set to minimum - jwpartain1, does your pedal operate like this?

Attached is the breadboard layout I'm using. Not included is the power supply section.
Philosophers Tone DIYLC Breadboard Layout.png
There is quite a lot of info here. And while the schematic may not be perfect, I think one can gather the gist of the things happening here. mysticwhiskey has put a lot of time into this, maybe one of you can pick up where he left off? :thumbsup

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mysticwhiskey
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Post by mysticwhiskey »

I don't have any updates at this stage - I've been busy on other projects and haven't played around with the breadboarded circuit since my last update. I guess I've given all the information I have: schematic, PCB and breadboard layout, and my testing results. I don't really have any more information to add at the moment.

I don't know when I'll get the time to sit down and play with this more - as it stands, the circuit seems to be working. The compression is a little weaker than the real thing, and the wet signal is a bit noisier than I'd like - this could be due to the breadboarded circuit not being shielded and likely the breadboard layout is suboptimal. I'd suggest the next steps would be to get hold of a NE5532 opamp to see if this has a marked improvement in terms of noise, and also to try a genuine vactrol (instead of an ordinary LDR/LED pair) to see if the compression improves. In the meantime if someone would like to breadboard the circuit, and take this further, go for it! :thumbsup

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