nate433
Member
Oh I love the OD-3 way more! Never could gel with BD-2. It may be one of my fav bass drives though (Less I Know the Better anyone?)
This is a commission for a friend, but he wanted some extra options outside of stock.
This Week on the Breadboard: Blues Driver BD-2 & BD-2w - part 4
- Thread starter Chuck D. Bones
- Start date
This is a commission for a friend, but he wanted some extra options outside of stock.
Chuck D. Bones
Circuit Wizard
The left (TIGHT) switch is correct. The right switch (FAT) is wrong.
Move the wire from the lower left terminal to the middle right terminal.
Move the wire from the upper right terminal to the middle left terminal.
And remember, there are parts installed in the pads where the wires go. You can solder the new parts and wires to the part leads on the top side or to the pads on the back side of the board. In either case, I recommend 26AWG stranded wire. There is room on the back, so I'd recommend putting the new parts & wires there. Test it all before you box it up.
Move the wire from the lower left terminal to the middle right terminal.
Move the wire from the upper right terminal to the middle left terminal.
And remember, there are parts installed in the pads where the wires go. You can solder the new parts and wires to the part leads on the top side or to the pads on the back side of the board. In either case, I recommend 26AWG stranded wire. There is room on the back, so I'd recommend putting the new parts & wires there. Test it all before you box it up.
nate433
Member
Thanks again!
For anyone else that pops in here and prefers visual aides here's the corrected wiring
Still incorrect, see next post!
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Chuck D. Bones
Circuit Wizard
I missed one:
Move the wire from the lower right switch terminal to the upper right.
Move the wire from the lower right switch terminal to the upper right.
nate433
Member
Thanks for all the help, here's the final final one
Chuck D. Bones
Circuit Wizard
We'll be looking for a Build Report on this one!
Synchrony Pedalworks
Well-known member
@Chuck D. Bones I need to send some thanks your way. I made the BD-2 in stock form, but I really didn't like it. I thought that the overdrive was muddy and didn't mix well with my guitars. On a whim, I decided to do your modifications, including the ultra bass mod. Wow! What a difference! The overdrive sparkles and has a vibrant sound. Many thanks!
Of the many modifications that you have noted in your column, is there several that you think really shine? I'd like to work my way through several of your circuit analysis and modifications, etc. Thanks again for being a great reasource.
Of the many modifications that you have noted in your column, is there several that you think really shine? I'd like to work my way through several of your circuit analysis and modifications, etc. Thanks again for being a great reasource.
Chuck D. Bones
Circuit Wizard
I prefer the OD-3 over the BD-2.
You have the right idea: work your way thru the articles in The Boneyard and see what catches your interest.
The Viceroy (Monarch), Mojito Deluxe, Timbre Man and Yankee ScrewDriver Deluxe are four fun and very different OD pedals. There are boards available for the first two here on PedalPCB.
You have the right idea: work your way thru the articles in The Boneyard and see what catches your interest.
The Viceroy (Monarch), Mojito Deluxe, Timbre Man and Yankee ScrewDriver Deluxe are four fun and very different OD pedals. There are boards available for the first two here on PedalPCB.
Hi Chuck, greetings from Korea. Apology for my poor English in advance..
Thanks to you, I can explore the depths of pedals. Your work always inspire me!
I recently built BD-2 from scratch on perfboard,
Basically stock version
+ your Tight/Fat switch
+ JFET biasing with J201 (10K trimpot)
+ Dual A100K used
+ modded input impedance. (R2:220K->2M)
Your solution for dual pot is such a savior! (I wanted to build it in 1590A, but mini dual A250K is just impossible to get)
And Tight/Fat switches working great! The pedal is much useful with the mods.
However, with stock mode, the sound is somewhat harsh/fizzy than I expected. Not that extreme, but it’s enough to ruin most of sweet spot. Something like teeny-weeny splinter on fingers.
After some debugging, I finally suspected the input impedance thing, so changed back the resistor to stock value (2M -> 220K)
And it worked out! More creamy and smooth, But now the low input impedance is problem
I tried compare passive guitar direct / putting buffer (bypassed Klon) in front of BD-2.
Obviously, there’s definate difference in articulation and dynamics with buffer.
That creamy and smooth feeling is intact, and even more enhanced balance.
So I put buffer circuit from original Boss unit in, including 10K input resistor, 100n input cap(47n original. just..no-brainer), and modified for true bypassing (added 2M pulldown resistor, changed gate resistor 1M to 2M)
Now with zero gain/noon-ish volume makes unity clean, just like original BD-2.
It was much higher signal level with 2M gate resistor version without buffer.
I think Q1 is not just input, it has own role for limiting some signal into 1st stage.. like reducing input gain.
So putting ‘complete’ signal with ‘proper’ impedance makes it too hot, I guess?
p.s.
Before I change the input impedance thing, I swapped transitors BC560C-> 2N3906.. to match hfe range of original TRs.(250~500, aiming 300~400)
After swapping, the JFET bias have shifted, so I reset it.
Though 3906 has inferior S/N, it was not noticeable, and the tone balance became more stable.. I think. The drive tone is from TR, so I guess hfe is pretty influential..
p.s.2
I breadboarded OCD recently, and tried same thing with input impedance. (320K -> 1M)
And there was simillar result. not that much like BD-2 though, the high-end became messy and fizzy.
Thanks to you, I can explore the depths of pedals. Your work always inspire me!
I recently built BD-2 from scratch on perfboard,
Basically stock version
+ your Tight/Fat switch
+ JFET biasing with J201 (10K trimpot)
+ Dual A100K used
+ modded input impedance. (R2:220K->2M)
Your solution for dual pot is such a savior! (I wanted to build it in 1590A, but mini dual A250K is just impossible to get)
And Tight/Fat switches working great! The pedal is much useful with the mods.
However, with stock mode, the sound is somewhat harsh/fizzy than I expected. Not that extreme, but it’s enough to ruin most of sweet spot. Something like teeny-weeny splinter on fingers.
After some debugging, I finally suspected the input impedance thing, so changed back the resistor to stock value (2M -> 220K)
And it worked out! More creamy and smooth, But now the low input impedance is problem
I tried compare passive guitar direct / putting buffer (bypassed Klon) in front of BD-2.
Obviously, there’s definate difference in articulation and dynamics with buffer.
That creamy and smooth feeling is intact, and even more enhanced balance.
So I put buffer circuit from original Boss unit in, including 10K input resistor, 100n input cap(47n original. just..no-brainer), and modified for true bypassing (added 2M pulldown resistor, changed gate resistor 1M to 2M)
Now with zero gain/noon-ish volume makes unity clean, just like original BD-2.
It was much higher signal level with 2M gate resistor version without buffer.
I think Q1 is not just input, it has own role for limiting some signal into 1st stage.. like reducing input gain.
So putting ‘complete’ signal with ‘proper’ impedance makes it too hot, I guess?
p.s.
Before I change the input impedance thing, I swapped transitors BC560C-> 2N3906.. to match hfe range of original TRs.(250~500, aiming 300~400)
After swapping, the JFET bias have shifted, so I reset it.
Though 3906 has inferior S/N, it was not noticeable, and the tone balance became more stable.. I think. The drive tone is from TR, so I guess hfe is pretty influential..
p.s.2
I breadboarded OCD recently, and tried same thing with input impedance. (320K -> 1M)
And there was simillar result. not that much like BD-2 though, the high-end became messy and fizzy.
Attachments
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Chuck D. Bones
Circuit Wizard
That is amazing! You got it all in there!
It's not the HFE of the PNP transistor that affects the bias, it's Vbe.
I think the BD-2 sounds fizzy because the shift from clean to distorted is abrupt. Either the BJT is clipping or it's not, there's no in-between.
Changing the input resistance should have the same effect as rolling the Volume or Tone down on your guitar.
It's not the HFE of the PNP transistor that affects the bias, it's Vbe.
I think the BD-2 sounds fizzy because the shift from clean to distorted is abrupt. Either the BJT is clipping or it's not, there's no in-between.
Changing the input resistance should have the same effect as rolling the Volume or Tone down on your guitar.
Thank you for reply, sir!
Making mini pedal is my hobby(in hobby lol)
I usually make pedals in 1590A unless it has more than 4knobs..
And yes. even with reduced input, it still has fizzy decay and boomy bass. Well it’s not bad, just taste thing.. but I felt it too much with hot input.
Now I enjoy this little fizzness and warm base. Of course it’s way way more useful with C mode.
I think it’s not elegant and practical circuit design that need to put attanuated signal..
Anyway I cannot roll down guitar volume individually when BD-2 is somewhere in pedalboard chain, so the input buffer + low gate resistance was needed.. It was very hard work to sqeez in additional circuit into almost fully crowded case. whew. Maybe some simple RC filter should work..
Making mini pedal is my hobby(in hobby lol)
I usually make pedals in 1590A unless it has more than 4knobs..
And yes. even with reduced input, it still has fizzy decay and boomy bass. Well it’s not bad, just taste thing.. but I felt it too much with hot input.
Now I enjoy this little fizzness and warm base. Of course it’s way way more useful with C mode.
I think it’s not elegant and practical circuit design that need to put attanuated signal..
Anyway I cannot roll down guitar volume individually when BD-2 is somewhere in pedalboard chain, so the input buffer + low gate resistance was needed.. It was very hard work to sqeez in additional circuit into almost fully crowded case. whew. Maybe some simple RC filter should work..
Chuck D. Bones
Circuit Wizard
I can't explain why lowering the input resistance would change the tone in that way. Do you have an oscilloscope?
