The Fairfield Circuitry Barbershop is one of my favourite overdrives, although I am yet to try this version.
There's some subtle difference to version one, and it has a tone control, similar to the Millennium version. I think the most significant difference is the change to the output buffer.
FAIRFIELD CIRCUITRY BARBERSHOP VERSION 2 - VERO LAYOUT
TEARDOWN & SCHEMATIC BY GRAY BENCH ELECTRONICS
Credit to Gray Bench Electronics for both the video and schematic below. Check out his channel on YouTube, as there's great stuff there.
FAIRFIELD CIRCUITRY BARBERSHOP VERSION 2 vs V1- LTSPICE
Comparing version one and version two doesn't show many differences, apart from the tone switch, which is kind of obvious what that does. From what I can see, the frequency response of version two has a bit more bass. Removing the 2N2222 collector voltage supply from the sag control seems to have made the biggest difference, and the emitter was attached the volume control as well. I guess it's more stable this way.
This is the two side by side with the sag control swept, gain on 100%, tone control left off on V2.
The frequency response stays pretty flat on both, apart from a bit of bass roll-off. I've forgotten which one is which below - one is sweeping the sage, the other the gain.
Version 2 with tone switches on. 10n first, then 47n. 47n looks a bit steep for me. When I made a Millennium Edition work-a-like I used 3.9n and 12n, and that was enough for me.
Is the Q3 just a buffer in V2 ?
ReplyDeleteThanks for doing a layout for this! I think there are a few tweaks needed to the vero:
ReplyDelete- Missing cut under the 1uF cap from Q3 base to Volume 2
- Output should be from row 16 instead of 15
- 1M resistor from Q3 base to GND is disconnected by a cut, which can be removed if the above changes are made
Thanks for spotting that and letting me know. This is what happens when you have a working layout, and then decide to move things around and forget to check it again. Again, much appreciated.
ReplyDeleteMy 1N4148 was not enough, I replaced it with a 1N4007 and changed the *resistor values。Thank you for your contribution！
ReplyDeleteI didn’t notice that on the schematic. Normally a 1N5187 is used for polarity protection, which is what I listed on the vero layout. I’ll have to watch the tear down again to check.
DeleteHey Andy, did you ever end up building this? I’ve given it a try and I’m not getting any sound coming through. I made the suggested changes by the other guy in the comments but no luck.
ReplyDeleteHello - no I haven't built this one, as I had already made my own work-a-like version. I went over the schematic again, and compared it to the layout - I can't see any errors (schematic is on FSB).
Delete1) Check pinouts on the JFETS and your NPN transistor. Do they have the same pinout as shown?
2) Do you have an audio probe, can you trace the signal? The signal path on this one is very easy to follow.
Hey Andy thanks for taking the time to respond and check the schematic. I've confirmed the transistors and correct, so I built an audio probe and now I'm stumped. I have signal up until the first 2M resistor, so I tried replacing it with other 2M's and then even 2 1M's and I am not getting any signal from the output side of the resistor. Any idea how this would be possible? I'm fairly new to this so please let me know if I'm missing something obvious. Thanks!
DeleteHello - the audio signal doesn't travel through the 2M resistors, they go to ground. Here's where you want to check;
DeleteFirst off make sure the sag is wide open and you have voltage on pin 3. Do you have a multimeter?
The gate of Q1 - signal flows in through the 10n cap, then through the 33k resistor to get to the gate. If you don't have signal here, something is pretty wrong
You should have a boosted signal on pin 3 of the drive pot. Signal comes out of pin 2 of the drive pot. If you don't have signal here, look for issues around Q1.
Check for output on Q2 on row 6, just above the volume and tone connections. Should also be loud
Check pin 2 of the volume pot. Check the emitter of Q3
Hey Andy, thanks again for the response. I traced the signal out to Q1, but I was getting a quiet, distorted signal out of the D side of Q1, and no signal out to the Drive pot. I messed around with reflowing some holes and long story short ended up burning the board and losing some crucial copper spots. Going to call this one a failure and start anew. On the upside I've got an audio probe this time so hopefully it'll help with troubleshooting. One thing I wanted to confirm before trying again with a new board- is the diagram showing the pots orientated with their backs facing out? Or is the knob side up. Just wanted to make sure I'd read it right. Thanks for all the help and hopefully I can post here soon with a working build
ReplyDeleteOK - A project in the bin is not uncommon when you're getting started; I certainly had my fair share of write-offs, which is why some people stick to PCBs. PCBs are a safer bet, vero is always more difficult to make.
DeleteBurning the board = you need to practice soldering a bit more. I'd highly recommend a flux pen for any reflow work. Without flux, reworking solder can make more of a mess.
For pot pinouts, always viewed from the back. This will be the same for anyone elses layouts as well.
For this, you can build it in sections to make sure you get each stage working before moving on to the next.
Ya this was my first go at Vero, think I’ll just need to take my time. Thanks for the clarification on the pots!
ReplyDeleteHey Andy, me again. I started fresh and really took time to lay thing out cleanly, check all joints etc but I’m still losing signal at Q1. I’ve triple checked orientation so the issue must be a faulty component right? Any other ideas?
ReplyDeleteHello - that's a bit annoying. Do you have a way to test the pinout of your JFETs? Fake J201s will usually work to some degree, but just sound terrible compared to real ones.
DeleteDo you have a multimeter to check voltages? Maybe bypass the sag pot for the moment and run V+ directly to row 2. Feel free to send me some photos of both sides of the board via instagram messenge
Hey Andy, ya definitely frustrating! I was thinking the same, if they were fake they'd still atleast pass signal. I do have a multimeter so I'll give your suggestion a go. I'll also send you pics on instagram. Thanks for taking the time to help out, it's much appreciated.
Delete