Fairfield Circuitry - The Barbershop (gut)  [traced]

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

you are speaking about replacing those decoupling caps from 10uF to 4.7uF right ? then they'll let a bit less bass through

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fairfield
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Post by fairfield »

Yea, less bass with 4.7uF at source.

The zener is there to protect the mosfet. Max Vgs is 20V, in the rare case that this would happen, the zener would limit this to whatever value you got. I'm not sure about this but I think you could still use 18V with a 12V zener. As the zener conducts, the voltage drop on the 2M resistor goes up...

In any case, using The Barbershop with a supply higher than 9V is kinda lame. It becomes too clean, and the Sag knob doesn't have the same effect. I don't even think the circuit would clip at any setting if you used an 18V supply.

You could lower the resistor between the two gain stages, right before the drive pot, sending the 2nd stage into saturation much quicker... it becomes a different pedal.

Have fun with your build.
Guillaume Fairfield
Fairfield Circuitry

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MicMicMan
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Post by MicMicMan »

fairfield wrote:The zener is there to protect the mosfet. Max Vgs is 20V, in the rare case that this would happen, the zener would limit this to whatever value you got. I'm not sure about this but I think you could still use 18V with a 12V zener. As the zener conducts, the voltage drop on the 2M resistor goes up...
I think the tension limit accepted would be 12V (zener value) + the Vgd threshold of the mosfet (given it's a p channel), right ?

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jwpartain1
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Post by jwpartain1 »

Hey, just got this pedal together, I think I'm having trouble with the 3DPT. Bypass signal gets through, but when I engage the effect, it's like I'm still in bypass. Can somebody check this for me? :)

On the 3DPT:

Top left lug: I've got Input from board and a jump to bottom-middle lug

Top-mid: LED ground

Top- right : board output

Mid-left: IN jack

Mid-mid: grounds

Mid-right: OUT jack

Bottom left: jump to bottom-right lug

Thanks you guys.

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jwpartain1
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Post by jwpartain1 »

Or I might be getting thourhg the bypass in the right way.. My drive knob makes the signal bassier with the SAG all the way back, but other than that no big changes other than minor volume changes when I mess with knobs. Any ideas from y'all who have the circuit down?

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Post by jwpartain1 »

OK, so I've got signal, I had a problem with the way the SAG control was wired. Now, I'm getting signal through, but unity gain is max on the volume pot.. The signal I'm getting through is something like a light ring-mod, sorta distorted. I thought voltages might be the problem, so I checked the voltages at several points til I came up to lug 1 of the SAG pot (lefts the voltage out to the 2 JFETS and 2n2222) and measured 3.8V (9 V battery was approx 7.5V) when all the way open and 3.6 V when closed. I've checked the signal path and everything is kosher, so any ideas why I'm getting such a huge V drop across the sag pot?

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jwpartain1
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Post by jwpartain1 »

Should the SAG pot really be wired as shown in WhiteKeyhole's schem? With 2 & 3 wired together?

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fairfield
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Post by fairfield »

Sounds like the sag is wired as a fixed 10k resistor. Make sure you're using the 2nd schematic on page 3. And yes, lug 2 and 3 are wired together.
Guillaume Fairfield
Fairfield Circuitry

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Post by jwpartain1 »

Thanks Mr. Fairfield, I had several problems with my build that are now fixed, I mistook GATE for SOURCE on the J201's... :slap: This pedal is awesome, and a super design.

..now I'm just GAS-ing for your Randy's Revenge! Have a good one y'all.

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Post by jwpartain1 »

Hey, just wanted to share my build, first build actually. My wife painted it for me using acrylic paint (brushed) and we sprayed a lacquer on top. The switch on the side puts a 15k resistor in parallel with R6, dropping R6 to something like 10K if I'm correct. Mr. Fairfield had suggested subbing in a smaller value for R6, so I tried it out, sounds dirty :) Anyways, thanks to Mr. Fairfield and everyone else here.

And about the guy, we couldn't tell if "Barbershop OD" was referring to a barbershop quartet or.. an actual barber-shop, so we combined the two! The candy-cane was supposed to be a reference to a barber's pole.
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asimplesample
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Post by asimplesample »

Image
Hey, y'all...my contribution to the thread. Not built, but I think it's okay.

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astatine
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Post by astatine »

I built this one, but having a bit of trouble with the sag control - the pedal only passes sound from 0 - 5. It sounds amazing when full on, so I really want to get this sorted!

My voltages are

q1 - D 5.78 S 0.73 G 0
q2 - D 6.37 S 0.51 G 0
q3 - C 9.3 B6.37 E 5.81

Any ideas? Do those bias voltages look okay?

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cortezthekiller
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Post by cortezthekiller »

Hey,

I posted the layout for the Barbershop on page 2 which I drew on paper traced from an actual unit. It shows that the last stage transistor (2N2222) is actually oriented upside-down compared to the "verified" schematic. I've built a few units with the 2N2222 upside down as shown in the drawing and it works quite well. Is there anyone who can verify if that is the actual orientation in the barbershop or if I somehow drew it backwards, built it backwards, and had it work?

Thanks

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Post by cdeschenes »

asimplesample wrote:Image
Hey, y'all...my contribution to the thread. Not built, but I think it's okay.
Verified this layout and it works flawless. Instead of a sag pot I used a dpdt switch with 2 resistors to get 9v, 7v and 5v since they seem the be the setting I used the most.

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Post by pietro_moog »

astatine wrote:I built this one, but having a bit of trouble with the sag control - the pedal only passes sound from 0 - 5. It sounds amazing when full on, so I really want to get this sorted!

My voltages are

q1 - D 5.78 S 0.73 G 0
q2 - D 6.37 S 0.51 G 0
q3 - C 9.3 B6.37 E 5.81

Any ideas? Do those bias voltages look okay?

i have the same problem here

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1bottom
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Post by 1bottom »

Hi everyone.
Im trying to build this pedal, but I've found about 5 different layouts and there are some differences in parts.
They all agree on Q1 & 2 being J201's, and the Q3 being a 2N2222.
IS the ATP2222A a good replacement for the 2N2222?

And in some schematics, they have a Q4 VP3203 > others omit this. Is this part necessary or not?
:scratch:

Lastly, does the wattage rating of the 15v Zener Diode make much of a difference?

Thanks guys.

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Post by knutolai »

Read the thread. You can use a series diode instead of Q4, D1, R10, R11.

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Post by BuzzKing »

Anyone have any info about the new Millennium Edition Barbershop? I was gonna build a second Barbershop for my small pedalboard. Haven't found a schematic or vero layout. Would love to build the new edition,

Rick

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jighead81
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Post by jighead81 »

Looks like there's a tone switch on it now?

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Post by FremenWarrior »

The tone switch could change between different capacitors to cut the highs (ex: none-100pF-500pF).

Whats the purpose of the 47 ohms resistor (R10)? is part of the protection circuit?

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