Friedman BE-OD Pedal  [traced]

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Re: Friedman BE-OD Pedal

Postby rmroza » 06 Jun 2017, 19:49

Great work guys! I'd like to help, but have been out of the country the last couple of weeks and won't be back until this weekend!

I'd like to get this design 100% verified and as a baseline. I picked up the pedal months ago and have no problem taking/confirming measurements and de-populating if necessary.

In the end, personally, I'd like to understand the design as a baseline, then "correct" or make better, such as include a MID control and make the resonance circuit variable and not fixed, make the gain level more useable instead of not a lot of difference betwen 1 and 10 and having to adjust the trimmer inside.

I hope that together we can accomplish this and look forward to again the baseline design, then build up a tagboard and A-B it.
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Re: Friedman BE-OD Pedal [schematic v11]

Postby YellowBoy » 06 Jun 2017, 23:17

Latest version as verified by pakrat and Gavin at TagboardFX "as functioning."

bmx..the presence pot appears to be coming off C13 in JOK3RX's pics so I left it as is. I think this is the last wobbly area of the trace so if anyone cares to confirm?
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Re: Friedman BE-OD Pedal

Postby pakrat » 07 Jun 2017, 01:27

YellowBoy wrote:Latest version as verified by pakrat and Gavin at TagboardFX "as functioning."

bmx..the presence pot appears to be coming off C13 in JOK3RX's pics so I left it as is. I think this is the last wobbly area of the trace so if anyone cares to confirm?


I can confirm. C13 connects to lug 3 of the presence pot.

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Re: Friedman BE-OD Pedal

Postby YellowBoy » 07 Jun 2017, 01:33

Excellent! All we need now is your opinions on its sound comparison to the real deal and we can call it traced :D

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Re: Friedman BE-OD Pedal

Postby pakrat » 07 Jun 2017, 15:33

YellowBoy wrote:Excellent! All we need now is your opinions on its sound comparison to the real deal and we can call it traced :D


I didn't post any results last night because I found some issues. I am getting oscillation with my guitar volume down with the trimpot and level control cranked. The trimpot is backwards to the original so I'll try flipping it around. It sounds very close to the original but slightly less gain, maybe due to BAV99 vs 1N4148? The tight control does work but again, slightly different than the original. On the bright side, it still sounds great and feels more like an amp than a pedal. Did anyone else build the tagboardeffects version with the new updates added?

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Re: Friedman BE-OD Pedal

Postby hozy31 » 07 Jun 2017, 19:42

I have added the updates and i have just checked with trimpot and level cranked and yes i get some mild background hum. I was thinking it was the nature of a high gain circuit. Could it be those 110nfs coming of pin 8 dampen something?

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Re: Friedman BE-OD Pedal

Postby pakrat » 07 Jun 2017, 20:48

hozy31 wrote:I have added the updates and i have just checked with trimpot and level cranked and yes i get some mild background hum. I was thinking it was the nature of a high gain circuit. Could it be those 110nfs coming of pin 8 dampen something?


Did you remove C23 (C2 on tagboardeffects layout) and connect C8 to GND? Without that I get no oscillation but a lot less gain. The original is pretty high gain and has noise at extreme settings as you would expect, but mine is full on feedback even without a guitar plugged in so it seems to feeding back into itself somewhere.
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Re: Friedman BE-OD Pedal

Postby pakrat » 07 Jun 2017, 21:00

hozy31 wrote:Could it be those 110nfs coming of pin 8 dampen something?


I thought the same thing so I connected 100nf caps across pins 4+8 on the TL072 and 4+11 of the TL074 and no change. I should note that the oscillation isn't present while playing or when the volume on my guitar is at full, just when I lower or go to zero on the volume. Passive pickups seem to be worse for some reason. More testing later tonight.....
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Re: Friedman BE-OD Pedal

Postby Groovenut » 07 Jun 2017, 22:36

pakrat wrote:
hozy31 wrote:Could it be those 110nfs coming of pin 8 dampen something?


I thought the same thing so I connected 100nf caps across pins 4+8 on the TL072 and 4+11 of the TL074 and no change. I should note that the oscillation isn't present while playing or when the volume on my guitar is at full, just when I lower or go to zero on the volume. Passive pickups seem to be worse for some reason. More testing later tonight.....

I would recommend using a shielded conductor for the input wire. This circuit is high gain with high input impedance. Lead placement will be critical for an oscillation free pedal. The symptoms you describe sound to me like that's what is happening. When you roll your guitar volume off, you essentially lift the input, allowing it to float at 500k above ground. This makes it a bit of an antennae. Shielded wire will help keep the crazy amounts of signal radiation from the rest of the circuit away from the input.

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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 04:36

Thanks Groovenut, I had shielded cable going in but didn't on the out so i tried that too and there was no change, BUT....... I then tried the same settings on the original and it's exactly the same. Maybe when both are boxed it will improve but it doesn't matter since the level shouldn't be on 10 anyway.
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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 05:00

After handing this thing a serious beating with my soldering iron, I think we have a winner..... it sounds great and pretty much exactly like the real deal. I'm going to check the latest schematic posted by YellowBoy one last time but I think it is correct and good to go!
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Re: Friedman BE-OD Pedal

Postby J0K3RX » 08 Jun 2017, 05:28

Going by what Groovenut said in regards to the impedance.. Put a buffered tube screamer "non true bypass" in front of it and see if it resolves the problem.. You don't have to engage the screamer just stick it in front and see if it makes a difference.

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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 05:42

J0K3RX wrote:Going by what Groovenut said in regards to the impedance.. Put a buffered tube screamer "non true bypass" in front of it and see if it resolves the problem.. You don't have to engage the screamer just stick it in front and see if it makes a difference.


That works, no squeal! You are gonna love this thing if you haven't built it already.

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Re: Friedman BE-OD Pedal

Postby J0K3RX » 08 Jun 2017, 05:50

Are you 100% sure C14 is going to ground? Looks like one side is coming from R18-2k2 and the other side is going to the LED's and lug 3 of the treble pot? The pics I have are very difficult to see the traces..
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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 06:20

Yes, the latest schematic has it correct.... C14 goes to GND. The other side connects to R18, the two LEDs, and lug 3 of the treble pot.

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Re: Friedman BE-OD Pedal

Postby J0K3RX » 08 Jun 2017, 06:33

You could try this on the input and it may help with impedance issues..
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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 06:44

Thanks, I'll try that out tomorrow and post results.
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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 06:49

Going over the latest scheme it does have one error. R10 should be 22k instead of 10k. Other than that, it is correct. I may check it against the PCB tomorrow to be 100%

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Re: Friedman BE-OD Pedal

Postby YellowBoy » 08 Jun 2017, 09:32

pakrat wrote:Going over the latest scheme it does have one error. R10 should be 22k instead of 10k. Other than that, it is correct. I may check it against the PCB tomorrow to be 100%

Copy/Paste error sorry. Alex pointed it out to me yesterday when he sent me his new layout for another pair of eyes. I've held off fixing it till the whole scheme has been confirmed. Don't want to clutter the thread up with more schematics revisions.

Thanks for all your efforts pakrat. :hug:

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Re: Friedman BE-OD Pedal

Postby pakrat » 08 Jun 2017, 17:28

Thank you too, and everyone else for this group effort.

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