Fairfield County Signature (Two-Rock JM Sig) Build Thread

[rccolgan]

Hello! I'm here again but with a fresh build of the JM Sig circuit. Two-Rock made an Oak Cliff Special (SSS #002 clone) and the name was a play on where Stevie Ray Vaughan was raised so I decided early on calling this amp the Fairfield County Signature where John Mayer grew up in Connecticut. I designed a new circuit board that will easily fit inside one of Taylor's JM Chassis as well as a direct 1:1 standoff fit inside a Ceriatone JM chassis. My plan is to sell the power supply and signal boards as well once I confirm the build is good. Preorder linkhttps://www.thetonegeek.com/product-pag ... -pre-order

Blog entry about the build can also be found here: https://www.thetonegeek.com/single-post ... -signature

My goal with this build is as close to 1:1 as I can within reason. I personally had the opportunity to poke around inside a real JM Sig (one of the 25) with an endoscope, pictures of another real JM sig, and very detailed pictures from two different post-production "rogue" JM sigs to get a decent cross-section of what is really a true JM sig circuit. I cannot share the source photos from the very generous owners of the amps however many of you have already seen the layout with the correct values that I will use to build this one.

For parts, I've been very fortunate to receive an anonymous donation of Draloric resistors to start (THANK YOU). The Draloric 6-band E48 series carbon film resistors as used on the original seem to be nonexistent so I will have to substitute on occasion. I bought a few ClassicTone transformers for this build before they went belly-up. Silver stranded wire, silver coax, Philips BC bypass caps, 6PS & 715P orange drops, NTE/JB LNFB caps, Sprague filter caps, etc. Really psyched for this build and helping others achieve the same thing.

Google Photo Album: https://photos.app.goo.gl/VmgVuEo9qTDXYwNo8

-Ryan

[Guy77]

Those boards look great Ryan!
Looks like they will save time too with the traces that have been done for some of the wiring.

Cheers

Guy

[rccolgan]

Those boards look great Ryan!
Looks like they will save time too with the traces that have been done for some of the wiring.

Cheers

Guy

Thanks!! Yes, and a few less things to go wrong

[Vertigo]

Very cool. I've been kicking myself for not buying one of those chassis when they were available. It would be a great winter project.

After watching one of your videos, I thought you might enjoy one of these automatic center punches I have them staged around my shop and they're SO much easier to use than a punch and hammer.

[dbharris]

Awesome project!

I have the same center punch that Vertigo linked and it was a game changer for me.

-Dan

[erwin_ve]

Good to see your back in amps Ryan. Following this one.

Erwin

[rccolgan]

Thanks, all! I'm happy to be back with amp building. Pedal endeavor is cool however, the quantity thing is a beast if its own lol.

After watching one of your videos, I thought you might enjoy one of these automatic center punches I have them staged around my shop and they're SO much easier to use than a punch and hammer.

Awesome project!

I have the same center punch that Vertigo linked and it was a game changer for me.

-Dan

Thank you!! I bought it immediately after I saw your recommendation. I did a test last night and I think I'll never go back to using the hammer method lol. Maybe I'll dread drilling out pedals a little less now!

[rccolgan]

A few photos from the photo album: https://photos.app.goo.gl/VmgVuEo9qTDXYwNo8

(PS, heaters with 18ga ETFE is tough!) https://www.tubedepot.com/products/18-g ... e-100-feet

One thing I learned is that there is unshielded cable used a bit more in the run of 25. Specifically on the runs to and from the gain pot. The rogue post-Mayer use shielded coax. I chose to try the unshielded and I can always add the shielded later if noise is an issue.

Can anyone confirm that the blue K&M capacitors that Two-Rock used are actually 715P? The more and more I studied the caps, the more and more the 400v look exactly like the dimensions of the 715P series. Perhaps even the 600v. I feel funny using 715P since I'm so used to the 6PS/418 line like the majority of the Dumbles we see.

[jazzbass]

Hi Rayan,

as usual you did a great job , do you sell the power supply and signal boards? I would like to build another Wonderland with all the observations you have generously shared.
Unfortunately the customs, taxes and transportation costs make it too expensive to buy the chassis from Taylor and I think I will continue to buy the chassis from Tubetown and then drill the holes myself.

Thanks
A hug
Franco

[rccolgan]

Hi Franco! Once I confirm the boards are good and work to my standards (no noise, correct design, etc) I will make them available in the For Sale section on the site as well as my website. Thank you for your kind words!

[Vertigo]

Hey Ryan,

A couple of questions and an observation...

The boards look great! Would you mind sharing the PCB vendor and the software package? I've got a project going and have been working my way through KiCAD but I don't love it.

I was looking through your google photos and saw a rendering of the PCB. It looks like the through hole for the GNFB and 12K resistor intersects with the pathway for the B4 power node. In the odd chance that you hadn't already caught that, it seemed worthy to point out.

https://photos.google.com/share/AF1QipM ... 10QV9XV19R

[rccolgan]

Hey Ryan,

A couple of questions and an observation...

The boards look great! Would you mind sharing the PCB vendor and the software package? I've got a project going and have been working my way through KiCAD but I don't love it.

I was looking through your google photos and saw a rendering of the PCB. It looks like the through hole for the GNFB and 12K resistor intersects with the pathway for the B4 power node. In the odd chance that you hadn't already caught that, it seemed worthy to point out.

https://photos.google.com/share/AF1QipM ... 10QV9XV19R

Great observations! I had to go and check my final design to make sure the GNFB didn't intersect in the way you observed. Luckily the design software (EasyEDA) caught the error when I generated the Gerber fabrication file and then I subsequently corrected it. I uploaded the final version to the album just now. I appreciate your observation and am happy to hear feedback.

I plan on doing a how-to series soon on PCB design. I use EasyEDA for design (you do not need to draw a schematic first unless you want the software to do an additional layer of checks.) For this project, I dove straight into designing the PCB without the schematic. For fabrication, I used JLCPCB. The price is right and their boards have been top-notch and continuously getting new features. I'm using 2mm board thickness with these which is really nice and rigid.

[jazzbass]

Very cool. I've been kicking myself for not buying one of those chassis when they were available. It would be a great winter project.

After watching one of your videos, I thought you might enjoy one of these automatic center punches I have them staged around my shop and they're SO much easier to use than a punch and hammer.

Hi Vertigo,

thanks for the suggestion you gave about the automatic puncer, I have been looking for it for a while but I didn't know what name to look for. I found it on Amazon, ordered and it's already arrived. It is easy and accurate.

Franco

[Vertigo]

Hi Vertigo,

thanks for the suggestion you gave about the automatic puncer, I have been looking for it for a while but I didn't know what name to look for. I found it on Amazon, ordered and it's already arrived. It is easy and accurate.

Franco

I'm glad you found it useful and glad to offer something when usually all I have are questions.

[rccolgan]

Fast forwarding a lot quicker than I anticipated... Confirmed build! Sounds great with everything added up! Voltages are in line with the original units and I'm going to let it burn in a while and I'll measure again. I guess that means the boards are good too! The PCB was nice to work with. I did remove and replace a few resistors (I got some NOS stuff in) and the boards held up wonderfully with rework. I'm happy to make them available to everyone else well. https://www.thetonegeek.com/product-pag ... -pre-order

As always, TAG is such a wealth of knowledge that I'm happy to share back. I'll create a BOM and layout over the next couple of weeks with the corrected values as a foundation.