EHX Freedom Preamp schematic?

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the finger genius wrote:The layout is starting to confuse me more as I try to dig into the schematic, thinking I may need to start fresh - any specific process or tool(s) people are using for designing a layout? I'm by no means an expert, but the layout looks odd to me as well. assuming that we want a bipolar voltage, shouldn't the circuit ground actually lay on trace D of the board? and trace G that is now used as ground would actually be the -9 Volts rail? right now the IC is connected to +18 Volts and ground instead of +/- 9 Volts. also the 47k and 68k resistors in the middle of the board would be connected to 9 Volts of the volage divider.course I could be wrong, but that layout does not look right to me.

EHX Freedom Preamp schematic?

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Dr Tony Balls wrote:On the original there was a separate power switch to turn the power on/off. It wasnt connected to the stomp switch, and you dont use the stomp to turn on/off power. In any pedal from the last 40+ years the power is switched by plugging a cable into the input jack. You need to use a stereo jack for this, and the output can just be a normal mono jack.I found some details on how to do this for a single battery, anyone know how it might differ with two batteries / biploar supply?

EHX Freedom Preamp schematic?

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bassdriver wrote:the finger genius wrote:The layout is starting to confuse me more as I try to dig into the schematic, thinking I may need to start fresh - any specific process or tool(s) people are using for designing a layout? I'm by no means an expert, but the layout looks odd to me as well. assuming that we want a bipolar voltage, shouldn't the circuit ground actually lay on trace D of the board? and trace G that is now used as ground would actually be the -9 Volts rail? right now the IC is connected to +18 Volts and ground instead of +/- 9 Volts. also the 47k and 68k resistors in the middle of the board would be connected to 9 Volts of the volage divider.course I could be wrong, but that layout does not look right to me.The layout i created is very likely completely wrong and probably should not be followed... I kind of lost track of this project.

EHX Freedom Preamp schematic?

45
had the day off and finished this up. It works (as in, it passes signal and changes the signal when engaged.)A couple things to figure out - The tone knob doesn't seem to be making any change. Need to see if I missed something or if the wiring on the Tone pots is correct.I probably should have used a multi-turn trimmer as suggested earlier in this thread - I used one I had on hand which is single turn and it seems to jump in gain from none to ALL in a hair's turn.LED isn't working, not sure if it has something to do with bipolar power weirdness or something else. - edit - realized I had forgotten to wire the 9V+ to the switch which accounted for the LED not working, unfortunately now the true bypass is not working (when disengaged I'm not getting anything. I don't think this should be connected to adding the 9V to the switch but it's weird that it just started happening when I fixed it.)Thanks for everybody's help so far, will post back soon.

EHX Freedom Preamp schematic?

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I breadboarded it too this morning. Works fine. The tone control works as a high pass filter. The žbite œ pot cuts some highs when engaged. As for the trim pot I used a 5 K pot but you could probable go as low as 2.5 K to have a good control over the amount of distortion. I did not have a 2N5087 transistor so I used a random PNP transistor that I had around.I powered it from my bench supply with 18 volts and when turned down to 9 volts, the circuit works fine too. I does have a lower output and I guess it acts a little different in the control of the distortion.

EHX Freedom Preamp schematic?

47
the finger genius wrote:bassdriver wrote:I breadboarded it too this morning. Works fine. The tone control works as a high pass filter. The žbite œ pot cuts some highs when engaged. As for the trim pot I used a 5 K pot but you could probable go as low as 2.5 K to have a good control over the amount of distortion. I did not have a 2N5087 transistor so I used a random PNP transistor that I had around.I powered it from my bench supply with 18 volts and when turned down to 9 volts, the circuit works fine too. I does have a lower output and I guess it acts a little different in the control of the distortion.We re you using plus 9 / - 9 or just 18v? I m not clear on how it would work to just use 9v, this the first time I m trying to build something not directly from a kit.I think the confusing part about this circuit is that unlike in most pedal designs the negative side of the batteries (or the bench supply) IS NOT ground. The ground lays between the 2 10 K resistors and the 2 10uF caps. The negative side of the batteries is only connected to pin 4 of the IC. If you use your multimeter you should read + 9 volts from the center of the voltage divider to the plus side of the batteries and - 9 volts from the negative side of the batteries to the center (or in other words +9 from pin 8 to ground and -9 from pin 4 to ground.In that case, if you only use one battery or turn down the voltage to 9 volts you should read + 4.5/ - 4.5 volts. I only tried that to see if the circuit does work as well on lower voltage, and I think it does.

EHX Freedom Preamp schematic?

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the finger genius wrote:For the trim pot I used a 100k with the third prong clipped / disconnected ThanksNate posted another schematic in the Dr Balls thread:it has a 1K resistor instead of the trim pot. if you have a 5 or 10 K pot at hand I would try that. you will have much more control over the sound (if you only have a single turn pot).it also shows what happens at the output. I think you pass the full signal through the "bite" pot or you drop some highs through a low pass filter. so, yes pin 7 and the bite circuit are connected at the output.

EHX Freedom Preamp schematic?

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If there s anyone who would be inclined to review the wiring for the pots I would greatly appreciate it. I have Volume 2 going to ground, and Bite 2 and 3 wired together and connected to the circuit output (if I am reading the schematic , IC 7, 10n Cap, 4k7 resistor and the 2 and 3 terminals from bite pot are all connected to the circuit output - is that right or is just IC 7 connected to the circuit out? For the trim pot I used a 100k with the third prong clipped / disconnected Thanks

EHX Freedom Preamp schematic?

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bassdriver wrote:I breadboarded it too this morning. Works fine. The tone control works as a high pass filter. The žbite œ pot cuts some highs when engaged. As for the trim pot I used a 5 K pot but you could probable go as low as 2.5 K to have a good control over the amount of distortion. I did not have a 2N5087 transistor so I used a random PNP transistor that I had around.I powered it from my bench supply with 18 volts and when turned down to 9 volts, the circuit works fine too. I does have a lower output and I guess it acts a little different in the control of the distortion.We re you using plus 9 / - 9 or just 18v? I m not clear on how it would work to just use 9v, this the first time I m trying to build something not directly from a kit.

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