# Chop Shop (Barbershop)



## caiofilipini (Oct 3, 2021)

One more build that had been sitting in the queue for far too long and I finally wrapped it up tonight: the Chop Shop. Sounds great! I tend to like discrete overdrives more than opamp-based ones, and this one confirms it. Went with another Gørva enclosure, but decided to use a bare one to sort of match the Fairfield look, including the knobs. On the downside, I had the stupid idea of labeling the controls with a Sharpie. It looks terrible. Oh well, at least it sounds great!


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## Mentaltossflycoon (Oct 3, 2021)

Sharpie on a gorva actually makes me happy.


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## Feral Feline (Oct 3, 2021)

Looks great to me!


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## Preverb (Oct 4, 2021)

Can you get those knobs at Tayda??

I am considering this as a 1st build.  Just not sure if Pedalpcb is shipping to Aus currently since USPS stopped service here.


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## caiofilipini (Oct 4, 2021)

Preverb said:


> Can you get those knobs at Tayda??


I believe I got them from Smallbear.


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## SYLV9ST9R (Oct 4, 2021)

Preverb said:


> Can you get those knobs at Tayda??








						Search results for: '1400'
					






					www.taydaelectronics.com


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## BuddytheReow (Oct 4, 2021)

I like the sharpie look on this one. You've got good handwriting. Er, better than mine at least.


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## Preverb (Oct 4, 2021)

SYLV9ST9R said:


> Search results for: '1400'
> 
> 
> 
> ...



Thanks!  Didn't know the name was 1400.


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## caiofilipini (Oct 4, 2021)

BuddytheReow said:


> I like the sharpie look on this one. You've got good handwriting. Er, better than mine at least.


Whoa, this is probably the first time ever someone said something nice about my handwriting! Thanks! 😂


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## fig (Oct 4, 2021)

Very nice! How's that sag control? Oh, and what is between the 3PDT lugs please?


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## caiofilipini (Oct 4, 2021)

fig said:


> Very nice! How's that sag control? Oh, and what is between the 3PDT lugs please?


Thanks, Tim!

The sag control is very subtle. It seems to have some effect on the high end content, at least in my build and rig. But it's fun.
I used clipped leads from carbon comp resistors and diodes (the thicker ones) as jumpers on the 3PDT.


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## phi1 (Oct 4, 2021)

Question since you find the sag control to be subtle. (I find it to increase the distortion quite a bit). Where did you source your jfets? Did you check the drain voltages?


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## caiofilipini (Oct 4, 2021)

phi1 said:


> Question since you find the sag control to be subtle. (I find it to increase the distortion quite a bit). Where did you source your jfets? Did you check the drain voltages?



I did check the drain voltages, they're somewhere between 4V and 4.5V on both. I tend to run my amp fairly hot, though, so maybe the effects aren't as pronounced?


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## caiofilipini (Oct 4, 2021)

Ah, and my J201s are a mix between Mouser (InterFET), GuitarPCB (Fairchild) and Pedal Hacker (Fairchild).
The ones that brought the drain voltages to the 4V range were the ones from ON Semi, all the Fairchild ones had significantly lower Vgs(off).


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## zgrav (Oct 4, 2021)

see how much variation in voltage you are are getting on your transistors at each range of the sag control.  I don't think the effect should be subtle when you dial it down, but maybe this sag control is intended to be limited in this build


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## SYLV9ST9R (Oct 4, 2021)

@caiofilipini If I’m not mistaken, drain voltage should be around 6V. You can always replace the drain resistors with 10k or 20k trimmers to dial it in. I found it helped with the Sag. 
You can also use a B5K for the Sag to give it a bit more range, but biasing is key IMO.


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## caiofilipini (Oct 4, 2021)

You all just made me realize the position of the Sag pot should be taken into consideration when biasing. It looks like fully CCW, whatever comes through the power supply is provided to the circuit. As you turn the Sag control CW, it lowers the current going into the circuit. Which means I should probably have it set fully CCW when biasing, correct?


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## caiofilipini (Oct 4, 2021)

Sooooo, turns out you were all correct and I'm stupid. I turned Sag fully CCW, swapped the J201s that were there for a pair that biased right around 6V, and now the Sag control really makes a difference.

I recorded a quick clip demonstrating it. It starts with the bypass sound (guitar straight into amp), then the ChopShop with the Drive control almost dimed and Sag fully CCW. I move my way CW until it's dimed, then move my way back CCW:


__
		https://soundcloud.com/white-mockingbird%2Fchopshop-sag-demo

Thanks to @fig for asking the right question, and to @phi1, @zgrav and @SYLV9ST9R for pointing me in the right direction. Love how it sounds even more now!


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## SYLV9ST9R (Oct 4, 2021)

Glad you got it figured out! It's such a great OD.


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## Harry Klippton (Oct 4, 2021)

This is another project I'd never heard of, nor the original, but that clip sounds great and now I wanna build it! @caiofilipini your sound clips always sound so good!


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## caiofilipini (Oct 4, 2021)

Harry Klippton said:


> This is another project I'd never heard of, nor the original, but that clip sounds great and now I wanna build it! @caiofilipini your sound clips always sound so good!


Highly recommend it!

Also, thank you for the kind words! Great guitar, great amp, cool pedals... I'm just the messenger.


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## Feral Feline (Oct 5, 2021)

FWIW: On bass, I found my OG FC Barbershop's "SAG" to be subtle as well. 


Looking forward to building this and comparing Barbershop to Chop Shop, _tête-à-tête_.


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## caiofilipini (Oct 5, 2021)

Feral Feline said:


> king forward to building this and comparing Barbershop to Chop Shop, _tête-à-tête_.


Nice, keep us posted!


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## SYLV9ST9R (Oct 5, 2021)

Feral Feline said:


> FWIW: On bass, I found my OG FC Barbershop's "SAG" to be subtle as well.
> 
> 
> Looking forward to building this and comparing Barbershop to Chop Shop, _tête-à-tête_.


Yep, I’ll sometimes dial it in but mainly use 3 settings: full CCW, middle, full CW.

On the build I did for my friend, it compared well to my Modèle B.


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## Preverb (Oct 5, 2021)

Feral Feline said:


> FWIW: On bass, I found my OG FC Barbershop's "SAG" to be subtle as well.
> 
> 
> Looking forward to building this and comparing Barbershop to Chop Shop, _tête-à-tête_.


 A big part of why I want to build one of these is because I ordered a Quilter US amp recently.  I had a 101 in the past and it sounded similar to a tube amp clean but not 100% there.  People say combining the sag of the Barbershop and the Quilter makes it even closer to a typical tube amp.  The interesting thing is that when I read the build reports for this pcb, it sounds like many people feel the sag isn't making that much difference...


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## SYLV9ST9R (Oct 5, 2021)

Preverb said:


> A big part of why I want to build one of these is because I ordered a Quilter US amp recently.  I had a 101 in the past and it sounded similar to a tube amp clean but not 100% there.  People say combining the sag of the Barbershop and the Quilter makes it even closer to a typical tube amp.  The interesting thing is that when I read the build reports for this pcb, it sounds like many people feel the sag isn't making that much difference...


Properly biased, it does and is quite nice


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## caiofilipini (Oct 5, 2021)

SYLV9ST9R said:


> Properly biased, it does and is quite nice


Totally second this, it made a big difference in my build.


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## almondcity (Oct 5, 2021)

Welp, guess I'm making another one of these, my sag is very subtle too


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## caiofilipini (Oct 5, 2021)

almondcity said:


> Welp, guess I'm making another one of these, my sag is very subtle too


If you used sockets for your JFETs, it could be a matter of trying out different ones, which is exactly what I did.
But if you didn't, I highly recommend you do use sockets on your new build!


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## almondcity (Oct 5, 2021)

agreed, this was one of the first builds I did so I didn't know to use sockets


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## Preverb (Oct 6, 2021)

caiofilipini said:


> If you used sockets for your JFETs, it could be a matter of trying out different ones, which is exactly what I did.
> But if you didn't, I highly recommend you do use sockets on your new build!


Any suggestions for possible options for substitution for the J201s?  I assume this is more likely to affect the overdrive character rather than sag?


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## fig (Oct 6, 2021)

You might try a couple of 2N5457s or MPF102s... @caiofilipini, what other FETs did you audition?


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## caiofilipini (Oct 6, 2021)

I'd go for 2N5457s as well. I haven't auditioned any besides several J201s, though.


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## phi1 (Oct 6, 2021)

I think 2n5457 will need significant adjustment of the drain resistors to bias correctly, and will be lower gain. The sag knob may not work over the whole range. You could get it to work, and probably sound nice if biased correctly, but it wouldn’t sound like a barbershop then. 

I’d heartily recommend using the smd pre-soldered j201 from pedalpcb for this project.


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## almondcity (Oct 6, 2021)

I'm half considering trying to unsolder my old j201s and put in new ones, seems like it would almost be easier to build a whole new circuit though


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