Friedman BE-OD Pedal  [traced]

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rmroza
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Post by rmroza »

hey guys sorry still not able to contribute other than opinion and advice. been busy since flying in thursday night from mexico.

yeah, again, room for improvement on this pedal. yes, trimmer works in conjunction with gain for overall amount of gain but thing never cleans up. this is distortion-only pedal imho. not sure why they chose to call it an OD??!?

looks like its verified or just about. ill see if i can check some things tomorrow and sure i can make clips no problem....just timing

again, id like to verify the design 100%, then buikd it up and A-B just to make
sure. then, improve on it. again mid needs to be added, trimmer can be a pot as i see, there is some questionable designs such ad presence control or where placed. if this is an emulatir pedal....just like the original amp, add a variable resonance control rather than fixed. ...and any over suggestions, then build this up as a v2.0?!??
build this

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J0K3RX
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Post by J0K3RX »

Could easily place the presence pot just before the volume pot like the crunch box presence mod, and about a million other pedal designs... That would seem like the logical place for it unless there is a special reason for keeping it in front of the treble and bass?

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bool
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Post by bool »

My --theory-- is that the trimmer-hardclip-presence topologically tries to mimic the "poweramp" overdrive; that trimmer would in that scenario allow you to dial-in what you'd consider as a sort-of poweramp distortion "emu" on top of previous two gain stages.

In my --theory-- the treble and bass controls are precisely what they say they are; functionally they're for the purpose of interfacing/adjusting the pedal to your rig; and topologically they're where they're supposed to be - at the end of the "tone chain" (which would by my judgment end precisely at the presence pot/cap junction).

HTH

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Post by bmxguitarsbmx »

J0K3RX wrote:Could easily place the presence pot just before the volume pot like the crunch box presence mod, and about a million other pedal designs... That would seem like the logical place for it unless there is a special reason for keeping it in front of the treble and bass?
I don't build many stompboxes, I mostly build tube amps. High output impedances are acceptable in the stompbox community unlike in the tube amp community. An effects loop with more than 5k output impedance is not acceptable due to the capacitance of the cables it will drive (20ft=1n). The be-od already has a high output impedance at worst case scenario 30kOhms (1/2 (10k +50k vol pot)). 1/(2pi*30kOhm*1n)= 5.307kHz -3dB first order low pass filter. maybe that is a concern, maybe not. Adding the presence after the last gain stage would raise the impedance and lower the low pass corner frequency further.

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Post by alltrax »

I built it following the last version on tagboard, works perfectly and sounds huge.
For me the trimmer acts more like a treble or presence preset than a gain one and I really like it that way

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rmroza
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Post by rmroza »

Sounds like you guys have this thing 100% confirmed and verified!

Now, what can be done to improve it...more usable gain instead of full on distortion with only slight variation...and how and where to add a mid control?

I was thinking when I got this and heard the tone it was going to a FET-based amp emulator circuit, but that does not appear to be the case.

Anyway, any recommendations on the 2 requested improvements above? The gain trim will definitelyt not be a trimmer and control on the front when I build this up and using a larger enclosure.

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rmroza
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Post by rmroza »

On the Veroboard...what is the "CLR" supposed to be?!?

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Post by jalmonsalmon »

rmroza wrote:On the Veroboard...what is the "CLR" supposed to be?!?
For the LED

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rmroza
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Post by rmroza »

Resistor current limiter for LED?? ok

After reviewing a few things, a couple other questions....

The zener used in the actual unit was a BZX84B39?? If so, why was a 1N5817 20V used instead of a 1N5819, which is a 40V??

Also, in the actual it was indicated BAV99's were used, but why was a 1N4148 with 100V peak reverse current chosed instead of a 1N457, which is the same as original and 70v?!?

Just asking. Maybe one is better and closer to the original than another and current selections due to commonality?!??

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bool
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Post by bool »

I believe (this is purely my own personal opinion) that the dev team aimed to create a working DIY-project, not a 100% replica of the original circuit.

For a pedal that will be most likely powered with 9-12-18 Volts; a 1N5817 should be perfectly adequate - and by all means most easily upgraded to 5818 or a 5819.

1N4148s are perhaps the most used diodes in clipping circuits, and widely available so it's a real no-brainer to use these (instead of a more exotic part) as a "default".

HTH

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Post by YellowBoy »

bool wrote:I believe (this is purely my own personal opinion) that the dev team aimed to create a working DIY-project, not a 100% replica of the original circuit.

For a pedal that will be most likely powered with 9-12-18 Volts; a 1N5817 should be perfectly adequate - and by all means most easily upgraded to 5818 or a 5819.

1N4148s are perhaps the most used diodes in clipping circuits, and widely available so it's a real no-brainer to use these (instead of a more exotic part) as a "default".

HTH
Exactly. I just drew it as I thought would be most accessible to DIYer's (like myself). Don't know about you but I build mostly on vero so through hole components are a much better option for me and 4148's are as common as muck. If someone wants to go down the clone route...it says it right there...although they'll need to fiddle that bit to properly connect BAV99's

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rmroza
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Post by rmroza »

Ok, cool. Soo just due to convenience and commonized off-the-self components. If someone wants to swap in a different component or more closely to the original....no issues.

I'd like to order the components and build up and A-B it to my original.

Has the schematic been updated or is v1.2 the latest?!? I noticed differences between the v1.2 and veroboard, such as...vero has 100uF cap, but schematic has nothing larger than 47uF. the schematic has 3 TL072 dual Op Amp. the veroboard has 1 TL072 dual and 1 TL074 quad Op Amp!

...just saying differences and I'm an anal perfectionist!! lol Thanks for everyone's support! :)

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Jan1966
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Post by Jan1966 »

The TL074 is just 2 TLO72's in one package. TL072 dual opamp. TL074 quad opamp. The designer chose to use the TL074 as it worked best for him and his vero layout.
It will still sound the same.
Hope this helps.

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Post by marshmellow »

rmroza wrote:Resistor current limiter for LED?? ok

After reviewing a few things, a couple other questions....

The zener used in the actual unit was a BZX84B39?? If so, why was a 1N5817 20V used instead of a 1N5819, which is a 40V??

Also, in the actual it was indicated BAV99's were used, but why was a 1N4148 with 100V peak reverse current chosed instead of a 1N457, which is the same as original and 70v?!?

Just asking. Maybe one is better and closer to the original than another and current selections due to commonality?!??
rmroza wrote:Ok, cool. Soo just due to convenience and commonized off-the-self components. If someone wants to swap in a different component or more closely to the original....no issues.

I'd like to order the components and build up and A-B it to my original.

Has the schematic been updated or is v1.2 the latest?!? I noticed differences between the v1.2 and veroboard, such as...vero has 100uF cap, but schematic has nothing larger than 47uF. the schematic has 3 TL072 dual Op Amp. the veroboard has 1 TL072 dual and 1 TL074 quad Op Amp!

...just saying differences and I'm an anal perfectionist!! lol Thanks for everyone's support! :)
None of these differences matter one single bit for the sound. Perfectionism or not.

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Post by bugg »

rmroza wrote:The zener used in the actual unit was a BZX84B39?? If so, why was a 1N5817 20V used instead of a 1N5819, which is a 40V??
Most likely the 39V zener was a shunt across the DC supply input... Reverse polarity or any voltage above ~39V would be shunted to ground.

The 1N5817 is providing series (non-destructive) reverse polarity protection. Reverse polarity will simply be blocked by the reverse biased diode, not shunted to ground. This doesn't provide any sort of over-voltage protection, but does not run the risk of damaging a DC power supply or "breaking" the pedal by shorting the shunt diode.

From the average consumer point of view if the reverse polarity protection diode shorts the pedal is broken, it doesn't matter how many components were protected... The pedal still doesn't work.

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rmroza
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Post by rmroza »

Cool. Understood. So the way that the components are applied has no significant difference between exact component in pedal and that used in the Veroboard. Great. Thanks for explaining and how being applied to this application! :)

Looking forward at building this up and A-B'ing it. Still would like to understand how to better control the gain and go from distortion-only to boost-to-distortion range as well as applying a MID-control.

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Post by ThiagoFaraday »

Perhaps one of the ways to achieve greater gain control. Would be to place a double pot with its other terminals connected in the respective session of gain (before or after, not sure). I believe along with the correction of other values as well.

Just a guess :scratch:

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Post by Groovenut »

As J0K3RX alluded to earlier, one of the easiest ways to get a more useable gain sweep is to sub a LOG gain pot for the factory LIN pot. A LIN pot at 2% is a LOG pot at 50%. This should allow for a more reasonable increase in gain from min to max.
Another thing you might try is changing the R9/C8 combo. Try 47k/47n or 100k/22n. That will change the gain of that stage from 46 to 22 and 11 respectively.

But I'd try the LOG gain pot first.

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Post by rmroza »

Thanks Groovenut

I don't like the pot suggestion as that's only going to change the taper of when the gain comes in, but the amount on the bottom and top with the pot at "0" and 10" will still remain the same.

I'm ok with the "10" gain on the top side. I'm looking to take away gain from the bottom side, so really need it to go from like -5 to 10 or -10 to 10. We're missing the below "0" gain.

Since the first gain stage is fixed, this is very similar to Dave's amps. He keeps the 1st gain stage fixed, basically at "10" but with a given set of gain based on plate, cathode values and voltage divider, so ideally, stage 2 is there it would need to be controlled and similar to his amp(s). I'll try it once built up and get more usefull gain so that is goes from booster thru distortion instead of distortion to more distortion and no boost nor overdrive....a more useful pedal. Put two on the pedalboard and have one as an OD and one a full on distortion based on gain levels! :)

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Post by bmxguitarsbmx »

I like both Groovenut's ideas. I was able to get volume cleanup by simply omitting the BAV99 clipping diodes (admittedly on accident). Lowering the gain of this stage, through r9/c8, seems promising to me.

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